View Filing Data

$ (45,461,000)

$ (12,615,000)

$ (24,454,761)

^[1]

$ (5,226,445)

Net loss per share:

Weighted average common shares outstanding:

$ (4.71)

$ (5.30)

$ (10.27)

$ (2.20)

9,643,231

2,381,041

^[2]

2,381,041

Pro Forma

Other income (expenses):

$ (24,454,761)

Net loss per share:

Weighted average common shares outstanding:

$ (3.13)

Beginning balance at Dec. 31, 2012

7,823,352

[1]	Represents actual net loss.
[2]	Represents actual weighted average common shares outstanding-basic.

STATEMENTS OF CHANGES IN REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' DEFICIT - USD ($)

Total

Series A Redeemable Convertible Preferred Stock

Series B Redeemable Convertible Preferred Stock

Series C Redeemable Convertible Preferred Stock

Series D Redeemable Convertible Preferred Stock

Redeemable Convertible Preferred Stock

Common stock

Additional Paid-in Capital

Accumulated Deficit

$ (19,174,597)

$ 1,304,557

$ (20,479,154)

Redeemable convertible preferred stock, beginning balance at Dec. 31, 2012

$ 3,342,849

$ 3,312,465

$ 11,892,066

$ 18,547,380

Stock-based compensation expense

(5,226,445)

133,745

Ending balance at Dec. 31, 2013

(24,267,297)

1,438,302

(25,705,599)

Redeemable convertible preferred stock, ending balance at Dec. 31, 2013

18,547,380

3,342,849

3,312,465

11,892,066

18,547,380

Adjustment for change in par value

(24,454,761)

^[1]

(24,454,761)

(1,438,064)

$ 1,438,064

Stock-based compensation expense

213,758

Conversion of 2013 Convertible Notes into Series D Preferred

$ 4,159,232

4,159,232

Issuance of Series D Preferred as financing fee

1,500,000

Ending balance at Dec. 31, 2014

(48,508,300)

$ 238

$ 1,651,822

$ (50,160,360)

Redeemable convertible preferred stock, ending balance at Dec. 31, 2014

24,206,612

$ 3,342,849

$ 3,312,465

$ 11,892,066

$ 5,659,232

$ 24,206,612

Ending balance at Sep. 30, 2015

(45,461,000)

$ (5,746,000)

[1]	Represents actual net loss.

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

Cash flows from operating activities:

STATEMENTS OF CASH FLOWS - USD ($)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Dec. 31, 2014

Dec. 31, 2013

Adjustments to reconcile net loss to net cash used in operating activities:

$ (45,461,000)

$ (12,615,000)

$ (24,454,761)

^[1]

$ (5,226,445)

Gain on extinguishment of debt

(1,900,000)

Loss (gain) on sale or disposal of assets

(3,031)

11,876

Stock-based compensation expense

1,456,000

169,000

213,758

133,745

Non-cash interest expense

1,956,000

972,000

1,601,639

151,989

Amortization of debt issuance costs and debt discount

1,434,000

636,000

1,113,711

1,560,000

Depreciation and amortization expense

61,000

56,000

74,763

67,724

Fair value adjustment

26,512,000

4,002,000

7,222,631

(1,137,348)

Change in assets and liabilities:

Prepaid expenses and other assets

(576,000)

(536,000)

523,077

(3,898)

Accounts payable and accrued expenses

(1,784,000)

1,316,000

934,127

126,300

Current portion of convertible notes

1,020,000

77,000

Current portion of term notes

1,517,000

115,000

Net cash used in operating activities

(13,865,000)

(7,708,000)

(14,674,086)

(4,316,057)

Cash flows from investing activities:

Proceeds from sale of asset

2,000

5,000

Purchases of property and equipment

(95,000)

(19,000)

(48,723)

(50,968)

Net cash used in investing activities

(95,000)

(17,000)

(43,723)

(45,968)

Cash flows from financing activities:

Proceeds from initial public offering, net of underwriting discounts and commissions

59,892,000

Payment of deferred offering costs

(1,244,000)

Proceeds from issuance of debt

25,000,000

3,846,000

Repayment of line of credit

(35,000)

(34,845)

(4,516)

Payment of debt and stock issuance costs

(163,000)

Payment of deferred offering costs

(1,766,587)

Payment of debt issuance costs

(163,067)

Repayment of obligations under capital lease

(24,000)

(31,303)

(52,514)

Proceeds from exercise of warrants

88,000

Net cash provided by financing activities

62,714,000

24,778,000

23,004,198

3,788,970

Increase (decrease) in cash and cash equivalents

48,754,000

17,053,000

8,286,389

(573,055)

Cash and equivalents, beginning of period

10,255,021

1,968,632

2,541,687

Cash and equivalents, end of period

59,009,000

19,022,000

10,255,021

1,968,632

Supplemental cash flow information:

Cash paid for interest

1,000

2,577

4,880

Non-cash financing and investing activities

Conversion of preferred stock into common stock upon initial public offering

28,209,000

Conversion Feature on 2013 Convertible Notes and Put Option

1,150,000

Offering expense charged to equity

2,812,000

Reclassification of 2013 warrants to equity

1,110,000

Transfer of warrants to equity upon exercise

281,000

Capitalization of patents

162,000

Conversion of 2013 Convertible Notes and interest into Series D Preferred

4,160,000

4,159,232

Issuance of 2013 Warrants and Deerfield Warrant

7,610,000

410,000

Fixed assets financed by capital lease

$ 94,388

Embedded Deerfield put option allocated to debt discount

220,000

Issuance of Series D Preferred as transaction fee

1,500,000

Deferred offering costs included in accounts payable and accrued expense

$ 313,000

$ 314,947

Series D-1 Redeemable Convertible Preferred Stock

Cash flows from financing activities:

Proceeds from issuance of Series D-1 Preferred Stock

4,000,000

Series D Redeemable Convertible Preferred Stock

Cash flows from financing activities:

Proceeds from exercise of warrants

$ 2,000

[1]	Represents actual net loss.

Description of Business and Basis of Presentation	9 Months Ended	12 Months Ended
Description of Business and Basis of Presentation	Sep. 30, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	A. Description of Business and Basis of Presentation *Organization* KemPharm, Inc. (the “Company”) is a clinical-stage specialty pharmaceutical company engaged in the discovery and development of proprietary prodrugs. The Company was formed on October 30, 2006, and incorporated in Iowa, and reorganized in Delaware on May 30, 2014. Through the use of its Ligand Activated Therapy (“LAT”) platform technology, the Company is able to initiate and pursue the development of improved versions of widely prescribed, approved drugs. The Company has experienced recurring losses from operations and negative operating cash flows due to its ongoing research and development of its potential product candidates. Various internal and external factors will affect whether and when the candidates become approved drugs and how significant their market share will be. The length of time and cost of developing and commercializing these candidates and/or failure of them at any stage of the drug approval process will materially affect the Company’s financial condition and future operations. The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Rule 8-03 of Regulation S-X. Accordingly, they do not include all of the information and related notes required by accounting principles generally accepted in the United States of America for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included in the accompanying financial statements. Operating results for the nine months ended September 30, 2015, are not necessarily indicative of the results that may be expected for the full year ending December 31, 2015. This interim information should be read in conjunction with the audited financial statements included in the Company’s prospectus dated April 15, 2015, and filed with the Securities and Exchange Commission (“SEC”) pursuant to Rule 424 promulgated under the Securities Act of 1933, as amended. *Reverse Stock Split* In April 2015, the Company effected a 1-for-7.5 reverse stock split of its issued common stock. All applicable share data, per share amounts and related information in the unaudited condensed financial statements and notes thereto have been adjusted retroactively to give effect to the 1-for-7.5 reverse stock split. *Initial Public Offering* In April 2015, the Company completed an initial public offering (“IPO”) of its common stock. In connection with the initial closing of the IPO, the Company sold an aggregate of 5,090,909 shares of common stock at a price to the public of $11.00 per share. In May 2015, the underwriters in the IPO exercised their option to purchase additional shares pursuant to which the Company sold an additional 763,636 shares of common stock at a price equal to the public price of $11.00 per share. In the aggregate, net proceeds from the IPO including net proceeds from the underwriters’ exercise of their option to purchase additional shares, were $59.9 million, after deducting underwriting discounts and commissions of $4.5 million. In addition, offering expenses totaled $2.8 million. Upon completion of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock were converted or reclassified into 5,980,564 shares of common stock and all outstanding warrants to acquire shares of the Company’s redeemable convertible preferred stock became warrants to acquire the Company’s common stock. In connection with the IPO, the Company amended and restated its Amended and Restated Certificate of Incorporation to change the authorized capital stock to 250,000,000 shares, designated as common stock, and 10,000,000 shares, designated as preferred stock, each with a par value of $0.0001 per share. *Reclassifications* Certain prior year amounts have been reclassified to conform to the current year presentation. These reclassifications had no effect on previously reported net loss.	1. Description of Business and Basis of Presentation KemPharm, Inc. (the Company) is a clinical-stage specialty pharmaceutical company engaged in the discovery and development of proprietary new molecular entity (NME) prodrugs. The Company was formed on October 30, 2006 and incorporated in Iowa. Through the use of its Ligand Activated Therapy (LAT) platform technology the Company is able to initiate and pursue the development of improved versions of widely prescribed, approved drugs. The Company has experienced recurring losses from operations and negative operating cash flows due to its ongoing research and development of its potential product candidates. The Company also has a stockholders’ deficit at December 31, 2014. Various internal and external factors will affect whether and when the candidates become approved drugs and how significant their market share will be. The length of time and cost of developing and commercializing these candidates and/or failure of them at any stage of the drug approval process will materially affect the Company’s financial condition and future operations. The Company has financed its operations primarily through issuances of redeemable convertible preferred stock and convertible notes. Although the Company believes that it will be able to successfully fund its operations, there can be no assurances that the Company would be successful in obtaining additional financing. *Domicile Change* During 2014, the Company’s board of directors unanimously approved and authorized the Company to change its domicile from Iowa to Delaware. The domicile change became effective on May 30, 2014. Concurrent with the domicile change, the Company amended its Certificate of Incorporation to increase the number of its authorized shares of capital stock and create a par value for the shares. Following the amendment, the Company was authorized to issue 140,000,000 shares of common stock, par value $0.0001 per share, and 109,483,000 shares of preferred stock, par value $0.0001 per share. As a result of the change to par value common stock, the Company recorded an adjustment of $1,438,064 to reduce common stock and record additional paid-in capital. *Reverse Stock Split* On April 2, 2015, the Company effected a 1-for-7.5 reverse stock split of its issued common stock. All applicable share data, per share amounts and related information in the financial statements and notes thereto have been adjusted retroactively to give effect to the 1-for-7.5 reverse stock split. See Note 16.

Summary of Significant Accounting Policies

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

B. Summary of Significant Accounting Policies

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires the Company to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

On an ongoing basis, the Company evaluates its estimates, including those related to the useful lives of property and equipment, the fair value of the Company’s common stock prior to the IPO and assumptions used for purposes of determining stock-based compensation, income taxes, and the fair value of the derivative and warrant liability, among others. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable, the results of which form the basis for making judgements about the carrying value of assets and liabilities.

Application of New or Revised Accounting Standards—Adopted

From time to time, the Financial Accounting Standards Board (the “FASB”) or other standard-setting bodies issue accounting standards that are adopted by the Company as of the specified effective date.

On April 5, 2012, President Obama signed the Jump-Start Our Business Startups Act (the “JOBS Act”) into law. The JOBS Act contains provisions that, among other things, reduce certain reporting requirements for an emerging growth company. As an emerging growth company, the Company may elect to adopt new or revised accounting standards when they become effective for non-public companies, which typically is later than public companies must adopt the standards. The Company has elected not to take advantage of the extended transition period afforded by the JOBS Act and, as a result, will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for non-emerging growth companies.

In July 2013, the FASB issued Accounting Standards Update (“ASU”) No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exist (“ASU 2013-11”). ASU 2013-11 amends the presentation requirements of Accounting Standards Codification (“ASC”) Topic 740 Income Taxes and requires an unrecognized tax benefit to be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, similar tax loss, or a tax credit carryforward. To the extent the tax benefit is not available at the reporting date under the governing tax law or if the entity does not intend to use the deferred tax asset for such purpose, the unrecognized tax benefit should be presented as a liability and not combined with deferred tax assets. ASU 2013-11 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. The amendments are to be applied to all unrecognized tax benefits that exist as of the effective date and may be applied retrospectively to each prior reporting period presented. The Company adopted the new standard effective January 1, 2014. The adoption of ASU 2013-11 did not have a material impact on the Company’s financial statements as no uncertain tax positions existed as of December 31, 2014 and September 30, 2015.

In June 2014, the FASB issued ASU No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation (“ASU 2014-10”). This ASU removes all incremental financial reporting requirements for development stage entities, including the removal of ASC Topic 915. The amendments in this ASU eliminate certain disclosure requirements to (1) present inception-to-date information in the statements of operations, cash flows and stockholder equity, (2) label the financial statements as those of a development stage entity, (3) disclose a description of the development stage activities in which the entity is engaged and (4) disclose in the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. The ASU clarifies that disclosures about risks and uncertainties required by ASC Topic 275 also apply to entities that have not commenced planned principal operations.

The Company early adopted ASU 2014-10. The amendments primarily relate to disclosure matters and, therefore, had no impact on the Company’s financial statements, other than the elimination of previously required disclosures including inception-to-date financial information.

Application of New or Revised Accounting Standards—Not Yet Adopted

In June 2014, the FASB issued ASU 2014-12, Compensation-Stock Compensation (ASC Topic 718): Accounting for Share-Based Payments when the Terms of an Award Provide that a Performance Target Could Be Achieved After the Requisite Service Period (“ASU 2014-12”). The amendments require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. ASU 2014-12 is effective for annual periods and interim periods within those annual periods beginning after December 15, 2015. Earlier adoption is permitted. Entities may apply ASU 2014-12 either (a) prospectively to all awards granted or modified after the effective date or (b) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. If retrospective transition is adopted, the cumulative effect of applying this ASU as of the beginning of the earliest annual period presented in the financial statements should be recognized as an adjustment to the opening retained earnings balance at that date. Additionally, if retrospective transition is adopted, an entity may use hindsight in measuring and recognizing the compensation cost. The Company currently is evaluating the impact of the adoption of ASU 2014-12 on its financial statements and disclosures.

In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”), which amends ASC Subtopic 205-40 to provide guidance about management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related disclosures. Specifically, the amendments (1) provide a definition of the term “substantial doubt,” (2) require an evaluation every reporting period, (3) provide principles for considering the mitigating effect of management’s plans, (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans, (5) require an express statement and other disclosures when substantial doubt is not alleviated and (6) require an assessment for a period of one year after the date that financial statements are issued. ASU 2014-15 is effective for fiscal years ending after December 15, 2016, and for annual periods and interim periods thereafter. The Company is currently evaluating the impact of the adoption of ASU 2014-15 on its financial statements and disclosures.

In May 2014, the FASB issued ASU No. 2014-09, amending revenue guidance to clarify the principles for recognizing revenue from contracts with customers. The guidance requires an entity to recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which an entity expects to be entitled in exchange for those goods or services. The guidance also requires expanded disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Additionally, qualitative and quantitative disclosures are required about customer contracts, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. In August 2015, the FASB issued ASU No. 2015-14, which makes the guidance effective for the Company’s interim and annual periods beginning January 1, 2018. The Company is currently evaluating the impact of this guidance on its financial statements and disclosures.

In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest (Subtopic 835-30) (“ASU 2015-03”), which requires the debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with the presentation of debt discounts. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Adoption of this ASU will reduce assets and liabilities by the amount of the debt issuance costs, which are $1.5 million and $1.2 million at December 31, 2014 and September 30, 2015, respectively.

2. Summary of Significant Accounting Policies

Unaudited Pro Forma Presentation

The unaudited pro forma net loss per share for the year ended December 31, 2014 assumes (i) the conversion of the 2013 Convertible Notes as of January 1, 2014 or at the time the interest is accrued, and (ii) the conversion of all outstanding shares of redeemable convertible preferred stock as of January 1, 2014 or the time of issuance, if later, into an aggregate of 5,564,552 shares of common stock upon the completion of an initial public offering (IPO) (Note 14).

The Company believes that the unaudited pro forma information is material to investors because certain convertible notes converted into redeemable convertible preferred stock during the year ended December 31, 2014 and the conversion of the redeemable convertible preferred stock into common stock will occur upon the closing of an IPO. Therefore, the disclosure provides a measure of total liabilities, stockholders’ deficit and net loss per share that is comparable to what the Company will report as a public company.

Use of Estimates

On an ongoing basis, the Company evaluates its estimates, including those related to the useful lives of property and equipment, the fair value of the Company’s common stock and assumptions used for purposes of determining stock-based compensation, income taxes, and the fair value of the derivative and warrant liability, among others. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable, the results of which form the basis for making judgments about the carrying value of assets and liabilities.

Concentration of Credit Risk

Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of cash on deposit with multiple financial institutions, the balances of which frequently exceed insured limits.

Cash and Cash Equivalents

The Company considers any highly liquid investments with an original maturity of three months or less to be cash and cash equivalents.

Property and Equipment

The Company records property and equipment at cost less accumulated depreciation and amortization. Costs of renewals and improvements that extend the useful lives of the assets are capitalized. Maintenance and repairs are expensed as incurred. Depreciation is determined on a straight-line basis over the estimated useful lives of the assets, which generally range from five to fifteen years. Leasehold improvements are amortized over the shorter of the useful life of the asset or the term of the related lease. Upon retirement or disposition of assets, the costs and related accumulated depreciation and amortization are removed from the accounts with the resulting gains or losses, if any, reflected in results of operations.

Deferred Offering Costs

Upon the consummation of the Company’s planned IPO, deferred offering costs will be offset against the gross proceeds of the offering and included in stockholders’ deficit. If the offering is aborted, the deferred offering costs will be expensed immediately. Deferred offering costs of $0 and $1.5 million, consisting primarily of incremental legal and accounting fees incurred directly relating to the IPO, are included in other long-term assets on the balance sheets as of December 31, 2013 and 2014, respectively.

Debt Issuance Costs

Debt issuance costs incurred in connection with financing arrangements are amortized over the life of the respective financing arrangement using the effective interest method.

Supply Arrangements

The Company enters into supply arrangements for the supply of components of its product candidates. These arrangements also may include a share of future revenue if related product candidates reach commercialization. Costs under these supply arrangements, if any, are expensed as incurred (Note 8).

Impairment of Long-Lived Assets

Long-lived assets to be held and used are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets may not be recoverable. When such events occur, the Company compares the carrying amounts of the assets to their undiscounted expected future cash flows. If the undiscounted cash flows are insufficient to recover the carrying values, an impairment loss is recorded for the difference between the carrying values and fair values of the asset. No such impairment had occurred as of December 31, 2013 and 2014.

Fair Value of Financial Instruments

The accounting standard for fair value measurements provides a framework for measuring fair value and requires disclosures regarding fair value measurements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, based on the Company’s principal or, in absence of a principal, most advantageous market for the specific asset or liability.

The Company uses a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires the Company to use observable inputs when available, and to minimize the use of unobservable inputs, when determining fair value. The three tiers are defined as follows:

Level 1—Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets;

Level 2—Observable inputs other than quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities; and

Level 3—Unobservable inputs that are supported by little or no market data, which require the Company to develop its own assumptions.

Research and Development

Major components of research and development costs include cash compensation, stock-based compensation, depreciation and amortization expense on research and development property and equipment, costs of preclinical studies, clinical trials and related clinical manufacturing, costs of drug development, costs of materials and supplies, facilities cost, overhead costs, regulatory and compliance costs, and fees paid to consultants and other entities that conduct certain research and development activities on the Company’s behalf. Costs incurred in research and development are expensed as incurred.

The Company records nonrefundable advance payments it makes for future research and development activities as prepaid expenses. Prepaid expenses are recognized as expense in the statements of operations as the Company receives the related goods or services.

Patent Costs

Patent costs, including related legal costs, are expensed as incurred and recorded within general and administrative expenses on the statement of operations.

Income Taxes

The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax basis of assets and liabilities, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. Valuation allowances are recorded to reduce deferred tax assets to the amount the Company believes is more likely than not to be realized.

Uncertain tax positions are recognized only when the Company believes it is more likely than not that the tax position will be upheld on examination by the taxing authorities based on the merits of the position. The Company recognizes interest and penalties, if any, related to unrecognized income tax uncertainties in income tax expense. The Company did not have any accrued interest or penalties associated with uncertain tax positions as of December 31, 2013 and 2014.

The Company files income tax returns in the United States for federal and various state jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal and state and local income tax examinations for years prior to 2010, although carryforward attributes that were generated prior to 2010 may still be adjusted upon examination by the Internal Revenue Service if used in a future period. No income tax returns are currently under examination by taxing authorities.

Stock-Based Compensation

The Company measures and recognizes compensation expense for all stock-based payment awards made to employees, officers and directors based on the estimated fair values of the awards as of the grant date. The Company records the value of the portion of the award that is ultimately expected to vest as expense over the requisite service period. The Company also accounts for equity instruments issued to non-employees using a fair value approach under Accounting Standards Codification (ASC) subtopic 505-50. The Company values equity instruments and stock options granted using the Black-Scholes valuation model. The value of non-employee stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest and is recognized as an expense over the term of the related financing or the period over which services are received.

Basic and Diluted Net Loss per Share of Common Stock

The Company uses the two-class method to compute net loss per common share because the Company has issued securities, other than common stock, that contractually entitle the holders to participate in dividends and earnings of the Company. The two-class method requires earnings for the period to be allocated between common stock and participating securities based upon their respective rights to receive distributed and undistributed earnings. Holders of each series of the Company’s redeemable convertible preferred stock are entitled to participate in distributions, when and if declared by the board of directors, that are made to common stockholders and, as a result, are considered participating securities.

Segment and Geographic Information

Operating segments are defined as components of an enterprise (business activity from which it earns revenue and incurs expenses) for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker (CODM) is its Chief Executive Officer. The Company views its operations and manages its business as a single operating and reporting segment. All assets of the Company were held in the United States for the years ended December 31, 2013 and 2014.

Application of New or Revised Accounting Standards—Adopted

From time to time, the Financial Accounting Standards Board (the FASB) or other standard-setting bodies issue accounting standards that are adopted by the Company as of the specified effective date.

On April 5, 2012, President Obama signed the Jump-Start Our Business Startups Act (the JOBS Act) into law. The JOBS Act contains provisions that, among other things, reduce certain reporting requirements for an emerging growth company. As an emerging growth company, the Company may elect to adopt new or revised accounting standards when they become effective for non-public companies, which typically is later than public companies must adopt the standards. The Company has elected not to take advantage of the extended transition period afforded by the JOBS Act and, as a result, will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for non-emerging growth companies.

In July 2013, the FASB issued ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exist (ASU 2013-11). ASU 2013-11 amends the presentation requirements of ASC Topic 740 Income Taxes and requires an unrecognized tax benefit to be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, similar tax loss, or a tax credit carryforward. To the extent the tax benefit is not available at the reporting date under the governing tax law or if the entity does not intend to use the deferred tax asset for such purpose, the unrecognized tax benefit should be presented as a liability and not combined with deferred tax assets. ASU 2013-11 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. The amendments are to be applied to all unrecognized tax benefits that exist as of the effective date and may be applied retrospectively to each prior reporting period presented. The adoption of ASU 2013-11 did not have a material impact on its financial statements as no uncertain tax positions existed as of December 31, 2013 and 2014.

In June 2014, the FASB issued ASU No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation (ASU 2014-10). This ASU removes all incremental financial reporting requirements for development stage entities, including the removal of Topic 915 from the FASB Accounting Standards Codification (ASC). The amendments in this ASU eliminate certain disclosure requirements to (1) present inception-to-date information in the statements of income, cash flows and shareholder equity, (2) label the financial statements as those of a development stage entity, (3) disclose a description of the development stage activities in which the entity is engaged and (4) disclose in the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. The ASU clarifies that disclosures about risks and uncertainties required by Topic 275 also apply to entities that have not commenced planned principal operations.

The Company elected to early adopt ASU 2014-10 in 2013. The amendments primarily relate to disclosure matters and, therefore, have no impact on the Company’s financial statements, other than the elimination of previously required disclosures including inception-to-date financial information.

Application of New or Revised Accounting Standards—Not Yet Adopted

In June 2014, the FASB issued ASU 2014-12, Compensation-Stock Compensation (Topic 718): Accounting for Share-Based Payments when the Terms of an Award Provide that a Performance Target Could Be Achieved After the Requisite Service Period (ASU 2014-12). The amendments require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. ASU 2014-12 is effective for annual periods and interim periods within those annual periods beginning after December 15, 2015. Earlier adoption is permitted. Entities may apply ASU 2014-12 either (a) prospectively to all awards granted or modified after the effective date or (b) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. If retrospective transition is adopted, the cumulative effect of applying this ASU as of the beginning of the earliest annual period presented in the financial statements should be recognized as an adjustment to the opening retained earnings balance at that date. Additionally, if retrospective transition is adopted, an entity may use hindsight in measuring and recognizing the compensation cost. The Company is currently evaluating the impact of the adoption of ASU 2014-12 on its financial statements and disclosures.

In August 2014, the FASB issued ASU No. 2014-15,Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014-15), which amends ASC Subtopic 205-40 to provide guidance about management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related disclosures. Specifically, the amendments (1) provide a definition of the term “substantial doubt,” (2) require an evaluation every reporting period, (3) provide principles for considering the mitigating effect of management’s plans, (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans, (5) require an express statement and other disclosures when substantial doubt is not alleviated and (6) require an assessment for a period of one year after the date that financial statements are issued. ASU 2014-15 is effective for fiscal years ending after December 15, 2016, and for annual periods and interim periods thereafter. The Company is currently evaluating the impact of the adoption of ASU 2014-15 on its financial statements and disclosures.

In May 2014, the FASB issued guidance codified in ASC 606, Revenue Recognition—Revenue from Contracts with Customers, which amends the guidance in former ASC 605, Revenue Recognition, and becomes effective beginning January 1, 2017. The Company is currently evaluating the impact of the provisions of ASC 606 on its financial statements and disclosures.

In January 2015, the FASB issued ASU No. 2015-01, Income Statement - Extraordinary and Unusual Items (Subtopic 225-20); Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items, which eliminates from GAAP the concept of extraordinary items, stating that the concept causes uncertainty because (1) it is unclear when an item should be considered both unusual and infrequent and (2) users do not find the classification and presentation necessary to identify those events and transactions. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015, with early adoption permitted provided the guidance is applied from the beginning of the fiscal year of adoption. The Company does not expect this standard to have an impact on its financial statements upon adoption.

Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2014

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Prepaid Expenses and Other Current Assets

3. Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following:


	December 31,
	2013		2014
Income tax receivable	$	20,427	$	22,415
Leased equipment deposit		41,760		—
Other current assets		8,783		178

Total	$	70,970	$	22,593

Property and Equipment

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment [Abstract]

Property and Equipment

4. Property and Equipment

Property and equipment consists of the following:


	December 31,
	2013		2014
Laboratory equipment	$	537,058	$	530,495
Computers and hardware		56,156		72,691
Furniture and office equipment		105,048		137,235
Leasehold improvements		6,226		6,226

Total property and equipment		704,488		746,647
Less: accumulated depreciation and amortization		(324,285)		(394,453)

Property and equipment, net	$	380,203	$	352,194

The Company leases various equipment under capital lease agreements. The assets under capital leases are included in property and equipment as follows:


	December 31,
	2013		2014
Furniture and office equipment	$	94,388	$	94,388
Less: accumulated depreciation and amortization		(3,146)		(12,585)

	$	91,242	$	81,803

The estimated useful lives of property and equipment are as follows:


Asset Category		Useful Life (in years)
Laboratory equipment		10
Computers and hardware		5-7
Furniture and office equipment		5-10
Leasehold improvements		10-15

Depreciation and amortization expense, including amounts pertaining to assets held under capital leases, was $67,724 and $74,763 for the years ended December 31, 2013 and 2014, respectively.

Accounts Payable and Accrued Expenses

12 Months Ended

Dec. 31, 2014

Payables and Accruals [Abstract]

Accounts Payable and Accrued Expenses

5. Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consist of the following:


	December 31,
	2013		2014
Accounts payable	$	386,071	$	1,670,486
Accrued interest		151,989		1,437,846
Accrued banking fees		700,000		700,000
Accrued payroll		127,514		94,723

Total	$	1,365,574	$	3,903,055

Debt Obligations

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Debt Disclosure [Abstract]

Debt Obligations

C. Debt Obligations

Deerfield Facility Agreement

On June 2, 2014, the Company entered into a $60 million facility agreement (the “Deerfield Facility Agreement”) with Deerfield Private Design Fund III, LP (“Deerfield”). The first payment to the Company under the terms of the Deerfield Facility Agreement consisted of a term loan of $15 million (the “Term Notes”) and a senior secured loan of $10 million (the “Deerfield Convertible Notes”). All loans issued under the Deerfield Facility Agreement bear interest at 9.75% per annum. Deerfield may convert any portion of the outstanding principal and any accrued but unpaid interest on the Deerfield Convertible Notes into shares of the Company’s common stock at an initial conversion price of $5.85 per share. At its option, the Company may convert the outstanding principal and accrued interest under the Deerfield Convertible Notes into shares of the Company’s common stock at an initial conversion price of $5.85 per share if either of the following occurs prior to June 30, 2016: (i) the FDA has approved, without requiring the performance of an efficacy study, a new drug application (“NDA”) for the Company’s product candidate, KP201/APAP, which consists of KP201, the Company’s prodrug of hydrocodone, formulated in combination with acetaminophen (“APAP”) for the treatment of acute pain; or (ii) the FDA has accepted the NDA for KP201/APAP for review and a qualified initial public offering, as defined in the Deerfield Facility Agreement, has occurred.

The Company also issued to Deerfield a warrant to purchase 14,423,076 shares of Series D redeemable convertible preferred stock (“Series D Preferred”) at an exercise price of $0.78 per share, which is exercisable until June 2, 2024 (the “Deerfield Warrant”). Upon completion of the IPO, the Deerfield Warrant automatically converted into a warrant to purchase 1,923,077 shares of the Company’s common stock at an exercise price of $5.85 per share. In the event that a Major Transaction occurs, as defined below, Deerfield may require the Company redeem the Deerfield Warrant for a cash amount equal to the Black-Scholes value of the portion of the Deerfield Warrant to be redeemed (the “Put Option”). A Major Transaction is (i) a consolidation, merger, exchange of shares, recapitalization, reorganization, business combination or other similar event; (ii) the sale or transfer in one transaction or a series of related transactions of all or substantially all of the assets of the Company; (iii) a third-party purchase, tender or exchange offer made to the holders of outstanding shares, such that following such purchase, tender or exchange offer a change of control has occurred; (iv) the liquidation, bankruptcy, insolvency, dissolution or winding-up affecting the Company; (v) the shares of the Company’s common stock cease to be listed on any eligible market; and (vi) at any time, the shares of the Company’s common stock cease to be registered under Section 12 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

In addition, the Company issued to Deerfield 1,923,077 shares of Series D Preferred as consideration for the loans provided to the Company under the Deerfield Facility Agreement. Upon completion of the IPO, these shares automatically reclassified into 256,410 shares of the Company’s common stock. The Company recorded the fair value of the shares of Series D Preferred of $1.5 million, to debt issuance costs on the date of issuance. The Company recorded the fair value of the Deerfield Warrant of $7.6 million and the fair value of the embedded Put Option of $220,000 to debt discount on the date of issuance. The debt issuance costs and debt discount are amortized over the term of the related debt and the expense is recorded as interest expense in the statements of operations.

The Company must repay one-third of the outstanding principal amount of all debt issued under the Deerfield Facility Agreement on the fourth and fifth anniversaries of the Deerfield Facility Agreement. The Company is then obligated to repay the balance of the outstanding principal amount on February 14, 2020.

Interest accrued on outstanding debt under the Deerfield Facility Agreement is due quarterly in arrears. Upon notice to Deerfield, the Company may choose to have one or more of the first eight of such scheduled interest payments added to the outstanding principal amount of the debt issued under the Deerfield Facility Agreement, provided that all such interest will be due on July 1, 2016. The Company has elected this option on all five of the scheduled interest payments to date. The accrued interest added to outstanding principal is reflected in the condensed balance sheets as current portion of convertible notes and current portion of term notes.

Deerfield is obligated to provide three additional tranches upon the Company’s request and after the satisfaction of specified conditions, including the FDA’s acceptance of an NDA for KP201/APAP, and, for the final two tranches, the subsequent approval for commercial sale thereof.

As of September 30, 2015, borrowings available to the Company under the Deerfield Facility Agreement were $35 million. Under the terms of the Deerfield Facility Agreement, future tranches to the Company are as follows:

The second tranche consists of a $10.0 million term loan that bears interest at 9.75% and a warrant to purchase 1,282,052 shares of the Company’s common stock at an exercise price of $5.85 per share.

The third and fourth tranches each consist of a $12.5 million term loan that bears interest at 9.75% and a warrant exercisable for the number of shares equal to 60% of the principal amount of such disbursement divided by 115% of the volume weighted average sales price of the Company’s common stock for the 20 consecutive trading days immediately prior to the date of such disbursement with an exercise price per share equal to such weighted average sales price.

Conversion of 2013 Convertible Notes into Series D Preferred

From June 2013 through October 2013, the Company issued 10.0% unsecured convertible promissory notes (the “2013 Convertible Notes”) for gross proceeds of $3.8 million. The 2013 Convertible Notes accrued interest from the date of issuance through the maturity date, with such interest payable in cash upon maturity. The 2013 Convertible Notes did not have a stated maturity date and instead matured under various scenarios, such as the sale of substantially all of the assets of the Company, dissolution of the Company, failure to observe covenants, and voluntary or involuntary bankruptcy. In accordance with the terms of the 2013 Convertible Notes, and effected by the written consent of the holders of a majority of the outstanding principal of such notes, on June 2, 2014, the principal amount of the 2013 Convertible Notes of $3.8 million and all accrued interest of $0.3 million converted into 5,332,348 shares of Series D Preferred at $0.78 per share. Upon the conversion of the 2013 Convertible Notes, the embedded conversion feature of the 2013 Convertible Notes and Put Option was marked to fair value and the balance of $1.9 million was recorded as a gain on extinguishment of debt.

Line of Credit

The Company has a $50,000 credit agreement with a financial institution (the “Line of Credit Agreement”). As of December 31, 2014 and September 30, 2015, the Company had $50,000 available under the Line of Credit Agreement. The Line of Credit Agreement is collateralized by all of the Company’s business assets as well as the personal guarantees of the Company’s officers. The Line of Credit Agreement contains no financial covenants. Borrowings under the Line of Credit Agreement carry interest at a rate equal to the prime rate plus 1.75% per annum. The Company is required to make interest only payments on any draws under the Line of Credit Agreement. The interest rate under the Line of Credit Agreement was 5% for the nine months ended September 30, 2014 and September 30, 2015.

6. Debt Obligations

Convertible Notes

From June 2013 through October 2013, the Company issued 10.0% unsecured convertible promissory notes (the 2013 Convertible Notes) for gross proceeds of $3,846,000. The 2013 Convertible Notes accrue interest from the date of issuance through the date of maturity, with such interest payable in cash upon maturity. The 2013 Convertible Notes do not have a stated maturity date and mature instead under various scenarios, such as the sale of substantially all of the assets of the Company, dissolution of the Company, failure to observe covenants, and voluntary or involuntary bankruptcy (the Put Option). The principal amount and accrued interest of the 2013 Convertible Notes automatically convert (the Conversion Feature) into subsequently issued equity securities if the Company issues equity securities in a transaction or series of related transactions that result in aggregate gross proceeds to the Company of at least $7,500,000 (a Qualified Financing). Upon a Qualified Financing, the principal amounts of the 2013 Convertible Notes and all accrued interest automatically convert into the equity securities issued pursuant to the Qualified Financing at a conversion price equal to the per share price paid by the purchasers of such equity securities in the Qualified Financing.

In connection with the issuance of the 2013 Convertible Notes, the Company also issued warrants (the 2013 Warrants) to purchase 1,079,453 shares of the same class and series of equity securities issued in the Qualified Financing for an exercise price equal to the per share price paid by the purchasers of such equity securities in the Qualified Financing. Upon the closing of an IPO, the 2013 Warrants will be exercisable only into shares of the Company’s common stock. The fair value of the 2013 Warrants at issuance was recorded as a debt discount. The Company determined that the 2013 Warrants should be recorded as a liability and stated at fair value at each reporting period (Notes 9 and 12).

The Company accounted for the embedded Conversion Feature and Put Option in the 2013 Convertible Notes under the derivative accounting guidance. Under this guidance, a company may be required to bifurcate an embedded feature from its host instrument and account for the embedded derivative as a free-standing derivative financial instrument that is measured at fair value at issuance and adjusted to its current fair value at each period. The Company determined that the embedded Conversion Feature and Put Option should be bifurcated from the 2013 Convertible Notes and recorded at fair value. The fair value of the Conversion Feature and Put Option was $1,150,000 at issuance and $1,360,000 at December 31, 2013 (Note 12). The fair value of the Conversion Feature and Put Option was $0 at December 31, 2014 since the 2013 Convertible Notes were converted in June 2014. Changes in fair value of the Conversion Feature and Put Option are recorded as a fair value adjustment within other (expense) income in the statements of operations.

Deerfield Facility Agreement

On June 2, 2014, the Company entered into a $60,000,000 facility agreement (the Deerfield Facility Agreement) with Deerfield Private Design Fund III, LP (Deerfield). The first payment to the Company under the terms of the Deerfield Facility Agreement consisted of a term loan of $15.0 million (the Term Notes) and a senior secured loan of $10.0 million (the Deerfield Convertible Notes). All loans issued under the Deerfield facility bear interest at 9.75% per annum. The Company also issued to Deerfield a warrant to purchase 14,423,076 shares of Series D redeemable convertible preferred stock (Series D Preferred) at an exercise price of $0.78 per share, which is exercisable until June 2, 2024 (the Deerfield Warrant). In the event that a Major Transaction occurs, as defined below, Deerfield may require the Company redeem the Deerfield Warrant for a cash amount equal to the Black-Scholes value of the portion of the Deerfield Warrant to be redeemed (the Embedded Deerfield Put Option). A Major Transaction is (i) a consolidation, merger, exchange of shares, recapitalization, reorganization, business combination or other similar event; (ii) the sale or transfer in one transaction or a series of related transactions of all or substantially all of the assets of the Company; (iii) a third-party purchase, tender or exchange offer made to the holders of outstanding shares, such that following such purchase, tender or exchange offer a change of control has occurred; (iv) the liquidation, bankruptcy, insolvency, dissolution or winding-up affecting the Company; (v) after an IPO, the shares of common stock cease to be listed on any eligible market; and (vi) after an IPO, the shares of common stock cease to be registered under Section 12 of the Exchange Act.

In addition, the Company issued to Deerfield 1,923,077 shares of Series D Preferred as consideration for the loans provided to the Company under the Deerfield facility. The Company recorded the fair value of the shares of Series D Preferred of $1,500,000 to debt issuance costs on the date of issuance. The Company recorded the fair value of the Deerfield Warrant of $7,610,000 and the fair value of the Embedded Deerfield Put Option of $220,000 to debt discount on the date of issuance. The debt issuance costs and debt discount are amortized over the term of the related debt and the expense is recorded as interest expense in the statements of operations.

Interest accrued on outstanding debt under the Deerfield facility is due quarterly in arrears. Upon notice to Deerfield, the Company may choose to have one or more of the first eight of such scheduled interest payments added to the outstanding principal amount of the debt issued under the Deerfield facility, provided that all such interest will be due on July 1, 2016.

Deerfield is obligated to provide three additional tranches upon the Company’s request and after the satisfaction of specified conditions, including the FDA’s acceptance of a New Drug Application (NDA) for KP201/APAP and, for the final two tranches, the subsequent approval for commercial sale thereof.

As of December 31, 2014, borrowings available to the Company under the Deerfield Facility Agreement were $35,000,000. Under the terms of the Deerfield Facility Agreement, future tranches to the Company are as follows:

The second tranche consists of a $10,000,000 term loan that bears interest at 9.75% and a warrant to purchase 9,615,385 shares of Series D Preferred at an exercise price of $0.78.

The third and fourth tranches each consist of a $12,500,000 term loan that bears interest at 9.75% and a warrant exercisable for the number of shares equal to 60% of the principal amount of such disbursement divided by 115% of the volume weighted average sales price of the Company’s common stock for the 20 consecutive trading days immediately prior to the date of such disbursement with an exercise price per share equal 115% of to such weighted average sales price.

Deerfield may convert all or any portion of the outstanding principal and any accrued but unpaid interest on the Deerfield Convertible Notes into shares of Series D Preferred at an initial conversion price of $0.78 per share. At its option, the Company may convert the outstanding principal and accrued interest under the Deerfield Convertible Notes into shares of Series D Preferred at an initial conversion price of $0.78 per share if either of the following occurs prior to June 30, 2016: (i) the FDA has approved, without requiring the performance of an efficacy study, the NDA for KP201/APAP for the treatment of acute pain; or (ii) the FDA has accepted the NDA for KP201/APAP for review and a qualified IPO, as defined in the Deerfield Facility Agreement, has occurred.

Upon the closing of an IPO, the Deerfield Convertible Notes will be convertible only into shares of the Company’s common stock upon the election of the note holder. Similarly, the Deerfield Warrant will be exercisable only for shares of the Company’s common stock upon the closing of an IPO.

Conversion of 2013 Convertible Notes into Series D Preferred

In accordance with the terms of the 2013 Convertible Notes, and effected by the written consent of the holders of a majority of the outstanding principal of such notes, on June 2, 2014, the principal amount of the 2013 Convertible Notes of $3,846,000 and all accrued interest of $313,232 converted into 5,332,348 shares of Series D Preferred at $0.78 per share. Upon the conversion of the 2013 Convertible Notes, the embedded Conversion Feature and Put Option was marked to fair value and the balance of $1,900,000 was recorded as a gain on extinguishment of debt.

Line of Credit

The Company has a $50,000 credit agreement with a financial institution (the Line of Credit Agreement). As of December 31, 2013 and 2014, the Company had $15,155 and $50,000 available under the Line of Credit Agreement, respectively. The Line of Credit Agreement is collateralized by all of the Company’s business assets as well as the personal guarantees of the Company’s officers. The Line of Credit Agreement contains no financial covenants. Borrowings under the Line of Credit Agreement carry interest at a rate equal to the prime rate plus 1.75% per annum. The Company is required to make interest only payments on any draws under the Line of Credit Agreement. The interest rate under the Line of Credit Agreement was 5% for the years ended December 31, 2013 and 2014.

Commitments and Contingencies

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

D. Commitments and Contingencies

From time to time, the Company is involved in various legal proceedings arising in the normal course of business. For some matters, a liability is not probable or the amount cannot be reasonably estimated and, therefore, an accrual has not been made. However, for such matters when it is probable that the Company has incurred a liability and can reasonably estimate the amount, the Company accrues and discloses such estimates.

In 2014, a former financial advisor of the Company filed a request with the Iowa District Court to declare valid a purported right of first refusal to serve as the Company’s exclusive financial advisor for specified strategic transactions and to receive fees for the specified strategic transactions irrespective of whether any such specified transaction occurred during or after the term of the financial advisor’s service agreement. This filing by the former financial advisor was made in response to an action initiated by the Company in 2013 seeking a declaratory judgement finding that such purported right was invalid and unenforceable. Two former members of the Company’s board of directors (the “Board”) joined the lawsuit as intervenors based on the former financial advisor’s purported assignment of its rights, or a portion thereof, under the agreement to the intervenors. In September 2015, the court granted summary judgement in favor of the Company with respect to the Company’s declaratory judgement action and the former financial advisor’s counterclaims and the Company separately entered into settlement agreements with each of the intervenors. The settlements reached with the intervenors did not differ from the accrual previously recorded by the Company by a material amount. The former financial advisor subsequently filed a notice of appeal of the court’s ruling with the Supreme Court of Iowa and the appeal is pending. The Company is unable to predict the timing or ultimate outcome of this litigation as of the date of this report. However, if it is determined that such purported right of first refusal and right to receive a cash fee related to any such specified strategic transactions are valid, then the Company could be required to pay the counterparty a portion of the consideration or proceeds received in any such specified strategic transaction, potentially including the Deerfield Facility Agreement, the IPO, the sale of the Company’s Series D-1 redeemable convertible preferred stock (“Series D-1 Preferred”) to Cowen KP Investment LLC (“Cowen”), and future capital raising and other strategic transactions.

7. Commitments and Contingencies

Legal Matters

From time to time, the Company is involved in various legal proceedings arising in the normal course of business. For some matters, a liability is not probable or the amount cannot be reasonably estimated and therefore an accrual has not been made. However, for such matters when it is probable that the Company has incurred a liability and can reasonably estimate the amount, the Company accrues and discloses such estimates.

In 2014, a former financial advisor and current warrant holder of the Company filed a request with the Iowa District Court to declare valid a purported right of first refusal to serve as the Company’s exclusive financial advisor for specified strategic transactions and to receive fees for the specified strategic transactions irrespective of whether any such specified transaction occurred during or after the term of the financial advisor’s service agreement. This filing by the former financial advisor was made in response to an action initiated by the Company in 2013 seeking a declaratory judgment finding that such purported right was invalid and unenforceable. A trial date for this matter has been scheduled for August 2015 and the Company is unable to predict the timing or outcome of this litigation as of the date of this report. However, if it is determined that such purported right of first refusal and right to receive a cash fee related to any such specified strategic transactions are valid, then the Company could be required to pay the counterparty a portion of the consideration or proceeds received in any such specified strategic transaction, including the Company’s IPO and future capital raising transactions.

Lease Agreements

The Company leases office and laboratory facilities in Iowa under a long-term non-cancelable operating lease. The Company’s lease for its Iowa facilities expires in September 2016 and includes a renewal option that could extend the lease for an additional three years. The Company leases office space in Florida under a long-term non-cancelable operating lease, which expires in October 2017.

The Company leases various laboratory, computer and other office equipment that are accounted for as capital leases and that require ongoing payments including interest expense. The capital leases are financed through various financial institutions and are collateralized by the underlying assets. As of December 31, 2014, the interest rate for assets under remaining capital leases was 0.65%.

Rent expense for non-cancelable operating leases was $144,896 and $193,372 for the years ended December 31, 2013 and 2014, respectively.

Future minimum lease payments under capital leases and non-cancelable operating leases as of December 31, 2014 were as follows:


Year Ending December 31,	Capital Leases		Operating Leases
2015	$	31,789	$	168,101
2016		26,492		146,923
2017		—		65,494

Total minimum lease payments		58,281	$	380,518

Less: amounts representing interest		(362)

Total	$	57,919

Supply Arrangement	12 Months Ended
Supply Arrangement	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supply Arrangement	8. Supply Arrangement As of December 31, 2014, the Company has one manufacturing arrangement that involves potential future expenditures related to research and development. In November 2009, the Company entered into a supply agreement with Johnson Matthey Inc. (JMI) whereby JMI has agreed to supply the Company with all of the KP201, the Company’s NME prodrug of hydrocodone, necessary for clinical trials and commercial sale for a price equal to JMI’s manufacturing cost and to provide process optimization and development services for KP201. The Company’s most advanced product candidate, KP201/APAP, is a combination of KP201 and acetaminophen (APAP) and is under development to treat acute moderate to moderately severe pain. KP201/APAP is designed to provide abuse-deterrent properties, which will be useful to address issues such as opioid abuse. The Company intends to submit an NDA for KP201/APAP in the second half of 2015 under Section 505(b)(2) of the Federal Food, Drug and Cosmetic Act. No expense was recorded under this agreement for the years ended December 31, 2013 and 2014. The Company must purchase all of its U.S. KP201 needs from JMI and JMI cannot supply KP201 to other companies. The term of the supply agreement extends as long as the Company holds a valid and enforceable patent for KP201 or until the tenth anniversary of KP201’s commercial launch, whichever date is later. Upon the expiration of such term, the agreement will automatically renew for a period of two years unless either party provides 12 months prior notice of its intent not to renew. Under the agreement, JMI will receive a tiered-based royalty share on the net sales on the commercial sale of a Federal Drug Administration approved drug incorporating KP201. No reliable estimate of the future payments can be made at this time.

Redeemable Convertible Preferred Stock and Warrants

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Text Block [Abstract]

Redeemable Convertible Preferred Stock and Warrants

E. Redeemable Convertible Preferred Stock and Warrants

Authorized, Issued, and Outstanding Redeemable Convertible Preferred Stock

In April 2015, the Company amended and restated its Certificate of Incorporation to decrease the number of its authorized shares of preferred stock to 10,000,000 shares with a par value of $0.0001 per share. As described in Note A, in April 2015, the Company completed an IPO of its common stock. Upon completion of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock were automatically converted or reclassified into an aggregate of 5,980,564 shares of the Company’s common stock. As of September 30, 2015, the Company had 10,000,000 shares of authorized and undesignated preferred stock, and did not have any preferred stock outstanding.

Preferred Stock Activity

The following table summarizes redeemable convertible preferred stock activity for the nine months ended September 30, 2015:

Shares of

Series A
Preferred

Series B
Preferred

Series C
Preferred

Series D
Preferred

Series D-1
Preferred

Total

Balance, December 31, 2014

9,704,215

6,220,000

18,557,408

7,255,425

–

41,737,048

Issuance of Series D-1 Preferred Stock

–

3,200,000

Exercise of Series D Preferred Warrants

–

3,205

–

3,205

Less: Conversion of Preferred Stock into Common Stock upon IPO

(9,704,215)

(6,220,000)

(18,557,408)

(7,258,630)

(3,200,000)

(44,940,253)

Balance, September 30, 2015

–

Series D-1 Redeemable Convertible Preferred Stock

In February 2015, the Company entered into a stock purchase agreement with Cowen in which Cowen agreed to purchase and the Company agreed to sell 3,200,000 shares of the Company’s Series D-1 Preferred for $1.25 per share, or an aggregate of $4 million. Upon completion of the IPO, these shares automatically converted into 415,584 shares of the Company’s common stock.

Warrants

As described in Note A, in April 2015, the Company completed an IPO of its common stock. Upon completion of the IPO, and as of September 30, 2015, warrants to purchase 15,499,324 shares of Series D Preferred were reclassified into warrants to purchase 2,066,543 shares of the Company’s common stock. As of December 31, 2014, the Company had outstanding warrants to purchase 15,502,529 shares of Series D Preferred at an exercise price of $0.78 per share. During the nine months ended September 30, 2015, warrants to purchase 3,205 shares of Series D Preferred were exercised.

During 2013, the Company issued $3.8 million of convertible notes and the warrants (the “2013 Warrants”) to purchase 1,079,453 shares of equity securities in a future financing meeting specified criteria (a “Qualified Financing”) (Note C). The 2013 Warrants allow the holders to purchase shares of the same class and series of equity securities issued in the Qualified Financing for an exercise price equal to the per share price paid by the purchasers of such equity securities in the Qualified Financing. When the Company entered into the Deerfield Facility Agreement, the 2013 Warrants became warrants to purchase 1,079,453 shares of Series D Preferred. Upon completion of the IPO, the 2013 Warrants automatically converted into warrants to purchase 143,466 shares of the Company’s common stock at an exercise price of $5.85 per share. The 2013 Warrants, if unexercised, expire on the earlier of June 2, 2019, or upon a liquidation event.

On June 2, 2014, pursuant to the terms of the Deerfield Facility Agreement, the Company issued the Deerfield Warrant to purchase 14,423,076 shares of Series D Preferred (Note C). The Company recorded the fair value of the Deerfield Warrant as a debt discount and a warrant liability. The Deerfield Warrant, if unexercised, expires on the earlier of June 2, 2024, or upon a liquidation event. Upon completion of the IPO, the Deerfield Warrant automatically converted into a warrant to purchase 1,923,077 shares of the Company’s common stock at an exercise price of $5.85 per share. The Company is amortizing the debt discount to interest expense over the term of the Term Notes and the Deerfield Convertible Notes.

The Company determined that the 2013 Warrants and Deerfield Warrant should be recorded as a liability and stated at fair value at each reporting period upon inception. As stated above, upon completion of the IPO, the 2013 Warrants and the Deerfield Warrant automatically converted into warrants to purchase the Company’s common stock. The Company determined that the 2013 Warrants should be marked to fair value and reclassified to equity upon closing of the IPO. The Deerfield Warrant remains classified as a liability and is recorded at fair value at each reporting period since it can be settled in cash. Changes to the fair value of the warrant liability are recorded through the statements of operations as a fair value adjustment (Note H).

9. Redeemable Convertible Preferred Stock and Warrants

Authorized, Issued, and Outstanding Redeemable Convertible Preferred Stock

Effective May 30, 2014, the Company amended its Certificate of Incorporation to increase the number of its authorized shares of preferred stock to 109,483,000 shares with a par value of $0.0001 per share.

The following table summarizes authorized, issued and outstanding Series A redeemable convertible preferred stock (Series A Preferred), Series B redeemable convertible preferred stock (Series B Preferred), Series C redeemable convertible preferred stock (Series C Preferred) and Series D Preferred as of December 31, 2014:


	Authorized		Outstanding		Issue Price		Conversion Price		Liquidation Preference
Series A Preferred		9,705,000		9,704,215	$	0.40	$	3.00	$	3,881,686
Series B Preferred		6,220,000		6,220,000	$	0.62	$	4.65		3,856,400
Series C Preferred		18,558,000		18,557,408	$	0.78	$	5.85		14,474,778
Series D Preferred		75,000,000		7,255,425	$	0.78	$	5.85		5,659,232

Total		109,483,000		41,737,048					$	27,872,096

Preferred Stock Activity

The following table summarizes redeemable convertible preferred stock activity for the years ended December 31, 2013 and 2014:


	Shares of
	Series A Preferred		Series B Preferred		Series C Preferred		Series D Preferred		Total
Balance, January 1, 2013		9,704,215		6,220,000		18,557,408		–		34,481,623

Balance, December 31, 2013		9,704,215		6,220,000		18,557,408		–		34,481,623
Shares issued upon conversion of 2013 Convertible Notes		–		–		–		5,332,348		5,332,348
Shares issued for financing fee to Deerfield		–		–		–		1,923,077		1,923,077

Balance, December 31, 2014		9,704,215		6,220,000		18,557,408		7,255,425		41,737,048

Series A Redeemable Convertible Preferred Stock (Series A Preferred)

On June 18, 2008, the Company adopted a resolution to amend its Articles of Incorporation to increase the number of authorized shares to 75,000,000, consisting of 50,000,000 shares of common stock, no par value, and 25,000,000 shares of preferred stock, no par value, of which 10,000,000 shares are designated as Series A Preferred.

On June 23, 2008, the Company entered into a private placement offering to secure additional equity capital. The private placement offering resulted in the issuance of 7,500,000 shares of Series A Preferred at $0.40 per share and the later issuance of warrants to purchase 99,929 shares of common stock at $3.90 per share. The gross proceeds of the private placement offering totaled $3,000,000 and direct offering costs were $403,757 resulting in net proceeds to the Company of $2,596,243. The warrants were separately issued to the placement agent for the private offering (Note 10).

During 2009, certain convertible debentures were exchanged for Series A Preferred. As a result, the Company issued 2,204,215 Series A Preferred shares for full redemption of the debentures.

Series B Redeemable Convertible Preferred Stock (Series B Preferred)

On April 22, 2009, the Company adopted a resolution to amend its Articles of Incorporation to authorize 7,000,000 shares of Series B Preferred, no par value.

On April 22, 2009, the Company entered into a private placement offering to secure additional equity capital. The private placement offering resulted in the issuance of 6,220,000 shares of Series B Preferred at $0.62 per share and the issuance of warrants to purchase 82,895 shares of common stock at $4.65 per share. The gross proceeds of the private placement offering totaled $3,856,400 and direct offering costs were $357,335, resulting in net proceeds to the Company of $3,499,065. The warrants were separately issued to the placement agent for the private offering (Note 10).

Series C Redeemable Convertible Preferred Stock (Series C Preferred)

On July 15, 2010, the Company adopted a resolution to amend its Articles of Incorporation to authorize 18,000,000 shares of Series C Preferred, no par value.

During 2010, the Company entered into a private placement offering to secure additional equity capital. In 2010, a total of 5,617,835 shares of Series C Preferred were sold at $0.78 per share. In conjunction with the private placement offering, the Company also issued a warrant to purchase 112,289 shares of common stock at $5.85 per share. The gross proceeds of the private placement offering totaled $4,381,916 and direct offering costs were $405,074, resulting in net proceeds to the Company of $3,976,842. The warrant was separately issued to the placement agent for the private offering (Note 10).

On July 15, 2011, the Company adopted a resolution to amend its Articles of Incorporation to increase the number of authorized shares of common stock, no par value, from 70,000,000 to 85,000,000 and Class C Preferred, no par value, from 18,000,000 to 33,000,000.

During 2011, the Company entered into a private placement offering to secure additional equity capital. The Company sold a total of 12,158,638 shares of Series C Preferred at $0.78 per share. In conjunction with the private placement offering, the Company also issued warrants to purchase 242,911 shares of common stock at $5.85 per share. The gross proceeds of the private placement offering totaled $9,483,738 and direct offering costs were $892,070, resulting in net proceeds to the Company of $8,591,668. The warrants were separately issued to the placement agent for the private offering.

During 2012, the Company sold a total of 864,268 shares of Series C Preferred at $0.78 per share. In conjunction with the private placement offering, the Company also issued warrants to purchase 16,430 shares of common stock at $5.85 per share. The gross proceeds of the private placement offering totaled $674,129 and direct offering costs were $148,636, resulting in net proceeds to the Company of $525,493. The warrants were separately issued to the placement agent for the private offering. In addition, 83,333 shares of Series C Preferred were repurchased from a former employee of the Company at $0.78 per share.

Series D Redeemable Convertible Preferred Stock

During 2014, the Company issued 7,255,425 shares of Series D Preferred at $0.78 per share in connection with the Qualified Financing (Note 6). On June 2, 2014, the Company issued 5,332,348 shares of Series D Preferred upon conversion of the 2013 Convertible Notes and 1,923,077 shares of Series D Preferred to Deerfield as a financing fee.

Significant terms of the redeemable convertible preferred stock (together the Preferred Stock) are as follows:

Conversion Rights

Each share of Series A Preferred, Series B Preferred, Series C Preferred and Series D Preferred is convertible, at the option of the holder, at any time after the date of issuance into the number of shares of common stock determined by dividing the original issue price by the conversion price upon a qualifying liquidation or capital event.

The initial conversion price of each share will be adjusted for stock splits, combinations, recapitalizations, reclassifications and similar events. The conversion price is subject to adjustment if the Company issues additional shares of common stock at a price less than the Series A Preferred, Series B Preferred, Series C Preferred and/or Series D Preferred conversion prices in effect at the time of such issuance.

All outstanding shares of Preferred Stock automatically convert into shares of common stock upon the closing of a Qualified Public Offering; an underwritten public offering of common stock that is not a Qualified Public Offering but that is approved by Deerfield and the board of directors; or the date specified by written consent or agreement of the holders of a majority of the then-outstanding shares of Preferred Stock, voting together as a separate class on an as-converted to common stock basis. A Qualified Public Offering is defined as the closing of the sale of shares of common stock to the public at a price of at least $9.375 per share in a firm-commitment underwritten public offering pursuant to an effective registration statement under the Securities Act of 1933, with at least $25,000,000 of gross proceeds to the Company and a listing of the common stock on the NASDAQ Stock Market or the New York Stock Exchange.

Dividend Rights

With respect to the Company’s payment of dividends or distributions, if any, the Series D Preferred ranks senior in priority to the Series C Preferred, which ranks senior in priority to the Series B Preferred, which ranks senior in priority to the Series A Preferred, which ranks senior in priority to all shares of common stock. Such dividends are payable only when, and if, declared by the board of directors and are noncumulative.

Voting Rights

The Company’s Series A Preferred, Series B Preferred and Series C Preferred are non-voting except to the extent voting rights are required by General Corporation Law of the State of Delaware. Each holder of Series D Preferred is entitled to cast the number of votes equal to the number of whole shares of common stock into which the shares of Series D Preferred held by such holder are convertible. Holders of Series D Preferred vote together with the holders of common stock as a single class.

Liquidation

Upon an Event of Liquidation, subject to the prior payment of any and all amounts required under the Deerfield Convertible Notes, the Deerfield Warrant and the Term Note, the assets and funds of the Company legally available for distribution, if any, shall be distributed among the holders of common stock and Preferred Stock as follows:

Before any distribution or payment is made to any holder of common stock, Series A Preferred, Series B Preferred or Series C Preferred, the holders of shares of Series D Preferred are entitled to be paid an amount equal to the liquidation preference amount with respect to each share of Series D Preferred. If the holders of Series D Preferred have been paid in full the liquidation preference amounts to which they are entitled, then, before any distribution or payment is made to any holder of common stock, Series A Preferred or Series B Preferred, the holders of shares of Series C Preferred are entitled to be paid an amount equal to the liquidation preference amount with respect to each share of Series C Preferred. If the holders of Series D Preferred and the Series C Preferred have been paid in full the liquidation preference amounts to which they are entitled, then, before any distribution or payment is made to any holder of common stock or Series A Preferred, the holders of shares of Series B Preferred are entitled to be paid an amount equal to the liquidation preference amount with respect to each share of Series B Preferred. If the holders of Series D Preferred, the Series C Preferred, and the Series B Preferred have been paid in full the liquidation preference amounts to which they are entitled, then, before any distribution or payment is made to any holder of common stock, the holders of shares of Series A Preferred are entitled to be paid an amount equal to the liquidation preference amount with respect to each share of Series A Preferred.

If, upon an Event of Liquidation, holders of the Preferred Stock have been paid in full the liquidation preference amounts to which they are entitled, the remaining assets and funds of the Company legally available for distribution, if any, will be distributed among the holders of the common stock and the Preferred Stock in proportion to the shares of common stock then held by them and the shares of common stock that they have the right to acquire upon conversion of the shares of Preferred Stock.

An Event of Liquidation means (i) any liquidation, dissolution or winding up of the Company, whether voluntary or involuntary, or (ii) any Deemed Liquidation Event. A Deemed Liquidation Event means (i) any merger, consolidation or share exchange transaction in which the Company is a party and the Company issues shares of its capital stock pursuant to such merger or consolidation (except any such merger, consolidation or share exchange involving the Company in which the shares of capital stock of the Company outstanding immediately prior to such merger, consolidation or share exchange continue to represent, or are converted into or exchanged for, shares of capital stock that represent, immediately following such merger or consolidation, at least a majority, by voting power, of the capital stock of the surviving or resulting corporation) or (ii) the sale, lease, transfer, exclusive license or other disposition, in a single transaction or series of related transactions, by the Company of all or substantially all the assets or capital stock of the Company.

As a result of the existence of the deemed liquidation feature, the Company determined that all series of Preferred Stock are redeemable upon the occurrence of a deemed liquidation event. They are carried at initial fair value at each reporting period and excluded from stockholders’ deficit in the accompanying balance sheets. If the occurrence of a deemed liquidation event becomes probable, all series of the Preferred Stock will be adjusted to liquidation value during that period.

Series D Preferred Protective Provisions

The Company cannot take any of the following actions without the written consent or affirmative vote of the holders of at least a majority of the issued and outstanding shares of Series D Preferred, which majority must include Deerfield:

liquidate, dissolve or wind up the business of the Company, or effect any merger or consolidation or any other Deemed Liquidation Event;

amend, alter or repeal any provision of the Certificate of Incorporation or Bylaws in a manner that adversely affects the holders of Series D Preferred;

create or issue shares of any additional class of capital stock unless the same ranks junior to the Series D Preferred with respect to distributions upon an Event of Liquidation, the payment of dividends and rights of redemption;

increase the authorized number of shares of Series D Preferred or increase the authorized number of shares of any other class of capital stock unless the same ranks junior to the Series D Preferred with respect to distributions upon an Event of Liquidation, the payment of dividends and rights of redemption;

issue any shares of Series D Preferred other than as contemplated by the Deerfield Facility Agreement, the Deerfield Convertible Notes or the Deerfield Warrant;

reclassify, alter or amend any existing security of the Company (i) that is pari passu with the Series D Preferred with respect to distributions payable upon an Event of Liquidation, the payment of dividends or rights of redemption, if such reclassification, alteration or amendment would render such other security senior to the Series D Preferred with respect to any such right, preference or privilege or (ii) that is junior to the Series D Preferred with respect to distributions payable upon an Event of Liquidation, the payment of dividends or rights of redemption, if such reclassification, alteration or amendment would render such other security senior to or pari passu with the Series D Preferred with respect to any such right, preference or privilege;

declare, pay, or make any dividends or other distributions to any holders of common stock, Series A Preferred, Series B Preferred, Series C Preferred, or any other capital stock that is junior to the Series D Preferred with respect to the payment of dividends or distributions, or to any holders of shares of a class of capital stock issued following the Series D Preferred original issue date that is pari passu to the Series D Preferred with respect to the payment of dividends;

purchase, redeem or otherwise acquire any shares of common stock, Series A Preferred, Series B Preferred, Series C Preferred, or any other capital stock that is junior to the Series D Preferred, or to any holders of shares of a class of capital stock issued following the Series D Preferred original issue date that is pari passu to the Series D Preferred; provided, however, that the approval by the Series D Preferred and Deerfield is not required for: (1) shares repurchased from former employees, consultants or directors of the Company in accordance with restricted stock purchase agreements with such employees, consultants or directors entered into with approval of the board of directors, (2) the repurchase of up to $100,000 of additional shares, in the aggregate, of such junior or pari passu classes or series of capital stock, and (3) redemptions of the Series D Preferred as expressly authorized in the Certificate of Incorporation; or

increase or decrease the authorized number of directors constituting the board of directors.

Warrants

As of December 31, 2014, outstanding warrants to purchase the Company’s Series D Preferred were as follows:


Issuance Date	Number of Underlying Shares		Exercise Price
2013		1,079,453	$	0.78
2014		14,423,076	$	0.78

		15,502,529

During 2013, the Company issued $3,846,000 of 2013 Convertible Notes and the 2013 Warrants to purchase 1,079,453 shares of equity securities in a future financing meeting specified criteria (a Qualified Financing) (Note 6). The 2013 Warrants allow the holders to purchase shares of the same class and series of equity securities issued in the Qualified Financing for an exercise price equal to the per share price paid by the purchasers of such equity securities in the Qualified Financing. When the Company entered into the Deerfield Facility Agreement, the 2013 Warrants became warrants to purchase 1,079,453 shares of Series D Preferred. The 2013 Warrants, if unexercised, expire on the earlier of June 2, 2019 or upon a liquidation event.

On June 2, 2014, pursuant to the terms of the Deerfield Facility Agreement, the Company issued the Deerfield Warrant to purchase 14,423,076 shares of Series D Preferred. The Company recorded the fair value of the Deerfield Warrant as a debt discount and a warrant liability. The Deerfield Warrant, if unexercised, expires on the earlier of June 2, 2024 or upon a liquidation event. The Company is amortizing the debt discount to interest expense over the term of the Term Notes and the Deerfield Convertible Notes.

The Company determined that the 2013 Warrants and Deerfield Warrant should be recorded as a liability and stated at fair value at each reporting period. Changes to the fair value of the warrant liability are recorded through the statements of operations as a fair value adjustment (Note 12).

Common Stock and Warrants

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Equity [Abstract]

Common Stock and Warrants

F. Common Stock and Warrants

Authorized, Issued, and Outstanding Common Shares

In April 2015, the Company amended and restated its Certificate of Incorporation to increase the number of its authorized shares of common stock to 250,000,000 shares. Of the authorized shares, 2,381,041 and 14,241,562 shares of common stock were issued and outstanding at December 31, 2014 and September 30, 2015, respectively.

At December 31, 2014 and September 30, 2015, the Company had reserved authorized shares of common stock for future issuance as follows:


	December 31, 2014		September 30, 2015
Conversion of Series A Preferred		1,293,838		–
Conversion of Series B Preferred		829,234		–
Conversion of Series C Preferred		2,474,121		–
Conversion of Series D Preferred		967,359		–
Conversion of Series D-1 Preferred		–		–
Conversion of Deerfield Convertible Notes		1,808,353		1,943,458
Outstanding awards under equity incentive plans		395,185		1,390,438
Outstanding common stock warrants		595,920		2,636,180
Outstanding Series D Preferred warrants		2,066,970		–
Possible future issuances under equity incentive plans		365,706		1,422,498

Total common shares reserved for future issuance		10,796,686		7,392,574

Common Stock Activity

The following table summarizes common stock activity for the nine months ended September 30, 2015:


	Shares of Common Stock
Beginning balance at December 31, 2014		2,381,041
Issuance of common stock in connection with initial public offering		5,854,545
Conversion of preferred stock to common stock in connection with initial public offering		5,980,564
Common stock warrants exercised		24,746
Common stock options exercised		666

Ending balance at September 30, 2015		14,241,562

The Company calculates the fair value of common stock warrants using a Monte Carlo simulation. There were no warrants exercised in the nine months ended September 30, 2014 and there were warrants exercised for an aggregate of 24,746 shares of common stock during the nine months ended September 30, 2015. From 2008 through 2012, the Company issued warrants to purchase 595,920 shares of common stock in its private placement offerings of Series A Preferred, Series B Preferred and Series C Preferred (the “Underwriter Warrants”) and for leasing laboratory space. The Company accounted for the Underwriter Warrants as a derivative liability, which is adjusted to fair value at each reporting period, with the change in fair value recorded within other expenses in the statements of operations.

10. Common Stock and Warrants on Common Stock

Authorized, Issued, and Outstanding Common Shares

Effective May 30, 2014, the Company amended its Certificate of Incorporation to increase the number of its authorized shares of common stock to 140,000,000 shares and change the common stock from no par value to $0.0001 per share. Of the authorized shares, 2,381,041 shares were issued and outstanding at December 31, 2013 and 2014.

At December 31, 2014, the Company had reserved authorized shares of common stock for future issuance as follows:


	Shares of Common Stock
Conversion of Series A Preferred		1,293,838
Conversion of Series B Preferred		829,234
Conversion of Series C Preferred		2,474,121
Conversion of Series D Preferred		967,359
Conversion of Deerfield Convertible Notes		1,808,353
Outstanding Series D Preferred Warrants		2,066,970
Outstanding awards under Incentive Stock Plan		395,185
Outstanding common stock warrants		595,920
Possible future issuances under Incentive Stock Plan		365,706

Total common shares reserved for future issuance		10,796,686

Common Stock Activity

There was no common stock activity during the years ended December 31, 2013 and 2014.

Liquidation Rights

In the event of any liquidation or dissolution of the Company, the holders of the common stock are entitled to share ratably with holders of the series of outstanding Preferred Stock, on an as-if-converted to common stock basis, in the remaining assets of the Company legally available for distribution after the payment of the full liquidation preference for all series of the outstanding Preferred Stock.

Dividends and Voting Rights

The holders of the common stock are entitled to receive dividends, when and if declared by the board of directors of the Company after all dividends on the Preferred Stock have been paid or funds have been set aside to pay such Preferred Stock dividends.

The holders of the common stock have the right to one vote per share of common stock.

Warrants on Common Stock

In connection with the issuances of Series A Preferred, Series B Preferred and Series C Preferred (Note 9), the Company issued warrants to purchase common stock to the underwriters as consideration for facilitating the private placements (Underwriter Warrants). The Underwriter Warrants were fully vested upon issuance and, if unexercised, expire on the earlier of the seventh anniversary of the issue date or upon the second anniversary of the first sale of securities to the public in an offering pursuant to an effective registration statement under the Securities Act. No Underwriter Warrants have been exercised since issuance and, as of December 31, 2014, the Company’s outstanding Underwriter Warrants and related exercise price by issuance were as follows:


Issuance Date	Number of Underlying Shares		Exercise Price
2008/2009		99,929	$	3.90
2009		82,895	$	4.65
2010		112,289	$	5.85
2011		242,911	$	5.85
2012		16,430	$	5.85

		554,454

The Underwriter Warrants include down-round protection in that the exercise price is adjusted if the Company issues any additional shares of common stock, including securities convertible into or warrants exercisable for common stock, without consideration or for consideration per share (or conversion price or exercise price per share) less than the exercise price then in effect for the Underwriter Warrants. The Underwriter Warrants also allow for net share settlement under the terms of the contract.

The Company determined that the Underwriter Warrants do not meet the criteria for equity classification and, consequently, the Underwriter Warrants were recorded as liabilities within the derivative and warrant liability on the balance sheets. These liabilities are adjusted to fair value at each reporting period (Note 12) with the change in fair value recorded within fair value adjustment within other (expense) income in the statements of operations.

At December 31, 2013 and 2014, the fair value of the Underwriter Warrants was $1,053,260 and $2,745,891, respectively.

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

Stock-Based Compensation

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Stock-Based Compensation

G. Stock-Based Compensation

The Company maintains a stock-based compensation plan (the “Incentive Stock Plan”) that governs stock awards made to employees and directors prior to completion of the IPO.

In November 2014, the Board, and in April 2015, the Company’s stockholders, approved the Company’s 2014 Equity Incentive Plan (the “2014 Plan”) which became effective in April 2015 and, effective as of such time the Company determined not to make any further grants under the Incentive Stock Plan. The 2014 Plan provides for the grant of stock options, other forms of equity compensation, and performance cash awards. The maximum number of shares of common stock that may be issued under the 2014 Plan is 2,266,666. In addition, the number of shares of common stock reserved for issuance under the 2014 Plan will automatically increase on January 1 of each year, beginning on January 1, 2016 and ending on and including January 1, 2024, by 4% of the total number of shares of the Company’s capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by the Board.

No stock options were exercised during the nine months ended September 30, 2014. During the nine months ended September 30, 2015, stock options to acquire 666 shares of common stock were exercised.

Stock-based compensation expense recorded under the Incentive Stock Plan and the 2014 Plan is included in the following line items in the accompanying statements of operations (in thousands):


	Nine Months Ended September 30,
	2014		2015
Research and development	$	37	$	308
General and administrative		132		1,148

	$	169	$	1,456

During the nine months ended September 30, 2015, the Company recognized $0.7 million of stock-based compensation expense related to performance-based awards included in general and administrative expenses and $0.1 million of stock-based compensation expense related to performance-based awards included in research and development expenses. These awards were in connection with the grant of fully vested stock options exercisable for an aggregate of 134,665 shares of common stock during the first quarter of 2015 and upon completion of the IPO during the second quarter of 2015. The Company did not recognize any stock-based compensation expense related to performance-based incentive awards during the nine months ended September 30, 2014, since the strategic initiatives set for the awards were not achieved or probable of achievement.

11. Stock-Based Compensation

The Company has a share-based compensation plan (the Incentive Stock Plan or the Plan) that is designed to allow the Company to attract and retain highly qualified employees and directors. No stock options were exercised during the years ended December 31, 2013 and 2014.

Under the Plan, the Company may grant awards of incentive stock, non-qualified stock options, and incentive stock options to employees, directors, and consultants. In July 2014, the Company’s Incentive Stock Plan was revised to increase the maximum number of shares issuable under the Plan from 666,666 to 800,000. Of this amount, 365,706 shares were available for awards as of December 31, 2014. Options may take the form of either incentive stock options or non-qualified stock options. Options granted under the Plan generally vest over one year to three years and expire in seven to 10 years from the date of grant. Stock-based compensation expense recorded under the Plan is included in the following line items in the accompanying statements of operations:


	Year Ended December 31,
	2013		2014
Research and development	$	29,296	$	61,467
General and administrative		104,449		152,291

	$	133,745	$	213,758

Stock Option Awards

The Company estimates the fair value of stock options using the Black-Scholes option-pricing model, which requires the use of subjective assumptions, including the expected term of the option, the current price of the underlying stock, the expected stock price volatility, expected dividend yield and the risk-free interest rate for the expected term of the option. The expected term represents the period of time the stock options are expected to be outstanding. Due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected term of the stock options, the Company uses the simplified method to estimate the expected term for its “plain vanilla” stock options. Under the simplified method, the expected term of an option is presumed to be the mid-point between the vesting date and the end of the contractual term. Some options, for example those that have exercise prices in excess of the fair value of the underlying stock, are not considered “plain vanilla” stock options. For these options, the Company uses an expected term equal to the contractual term of the option. Expected volatility is based on historical volatilities for publicly traded stock of comparable companies over the estimated expected term of the stock options. The Company assumes no dividend yield because dividends are not expected to be paid in the near future, which is consistent with the Company’s history of not paying dividends.

The Company recognizes compensation expense related to stock-based payment transactions upon satisfaction of the requisite service or vesting requirements. Forfeitures are estimated at the time of grant and revised based on actual forfeitures, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

Using the Black-Scholes option-pricing model, the weighted-average fair value of awards granted during the years ended December 31, 2013 and 2014 was $3.00 and $4.50 per share, respectively. The assumptions used to estimate fair value are as follows:


	Year Ended December 31,
	2013	2014
Risk-free interest rate	0.52% - 2.80%	0.91% - 2.70%
Expected term (in years)	4.04 - 10.00	7.00 - 10.00
Expected volatility	58.55% - 92.00%	86.00% - 95.00%
Expected dividend yield	0%	0%

The activity under the Plan for the year ended December 31, 2014 is summarized as follows:


	Number of Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Outstanding balance at January 1, 2014		296,256	$	5.24		7.24	$	–
Granted		112,262	$	5.85
Exercised		–		–
Cancelled		(13,333)	$	5.85

Outstanding balance at December 31, 2014		395,185	$	5.40		7.24	$	1,275,980

Exercisable at December 31, 2014		170,167	$	4.80		5.71	$	651,543

Vested and expected to vest at December 31, 2014		297,899	$	5.25		6.47	$	1,006,008

Information regarding currently outstanding and exercisable options as of December 31, 2014 is as follows:


	Options Outstanding			Options Exercisable
Exercise Price	Number of Shares		Weighted- Average Remaining Contractual Term (in years)	Number of Shares		Weighted- Average Remaining Contractual Term (in years)
$0.75		12,000	2.50		12,000	2.50
$3.00		20,667	3.54		20,667	3.54
$4.65		49,327	3.61		49,327	3.61
$5.85		313,191	8.24		88,173	7.82

		395,185	7.24		170,167	5.71

The total fair value of stock options vested during the years ended December 31, 2013 and 2014 was $173,579 and $175,697, respectively.

Unvested stock options as of December 31, 2013 and 2014 were as follows:


	Number of Unvested Shares As of December 31,
Exercise Price	2013		2014
$5.85		161,511		225,018

		161,511		225,018

As of December 31, 2014, there was $495,093 of total unrecognized compensation cost related to unvested share-based compensation arrangements granted under the Plan. That compensation cost is expected to be recognized over a weighted-average period of 1.56 years.

During 2012, certain executives were granted 80,000 performance-based stock options. These performance-based awards will vest if the Company achieves certain strategic initiatives, such as the achievement of certain clinical milestones or the occurrence of a liquidity event for stockholders. Compensation expense is recognized for the Company’s performance-based grants when the milestone is met or when it is probable that the milestone will be achieved, as determined on a case by case basis depending upon the milestone. The strategic initiatives set forth in these grants were not achieved or probable of achievement and, as such, the Company did not record any compensation expense for these awards for the years ended December 31, 2013 and 2014.

Additionally, during 2013, the Company promised an executive the right to receive 40,000 shares of common stock and 160,000 stock options if the Company achieves certain strategic initiatives, such as the closing of certain financing transactions or the occurrence of a change of control transaction. During the year ended December 31, 2014, the Company recognized $62,806 of stock-based compensation expense in connection with the grant of 13,333 fully vested stock options as a result of the Company entering into the Deerfield Facility Agreement.

Fair Value of Financial Instruments

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

H. Fair Value of Financial Instruments

The carrying amounts of certain financial instruments, including cash and cash equivalents and accounts payable, approximate their respective fair values due to the short-term nature of such instruments. The carrying amount of the line of credit approximates fair value due to the variable interest rate in that instrument.

The fair value of the Deerfield Convertible Notes and the Term Notes was $41.4 million and $13.5 million, respectively, at September 30, 2015. Both the Deerfield Convertible Notes and the Term Notes fall within Level 3 of the fair value hierarchy as their value is based on the credit worthiness of the Company, which is an unobservable input.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The Company evaluates its financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in which to classify them for each reporting period. This determination requires significant judgements to be made. The following table summarizes the conclusions reached regarding fair value measurements as of December 31, 2014, and September 30, 2015 (in thousands):


	Balance at December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	2,746	$	–	$	–	$	2,746
2013 Warrant liability		520		–		–		520
Deerfield Warrant liability		12,560		–		–		12,560
Embedded Put Option		140		–		–		140

	$	15,966	$	–	$	–	$	15,966


	Balance at September 30, 2015		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	7,674	$	–	$	–	$	7,674
Deerfield Warrant liability		32,615		–		–		32,615
Embedded Put Option		808		–		–		808

	$	41,097	$	–	$	–	$	41,097

The Company’s Underwriter Warrant liability, Deerfield Warrant liability, and the embedded Put Option on the Deerfield Warrant are measured at fair value on a recurring basis. The 2013 Warrant liability was recorded at fair value on a recurring basis through the completion of the IPO. As of December 31, 2014 and September 30, 2015, the Underwriter Warrant liability, the Deerfield Warrant liability and the embedded Put Option are reported on the balance sheet in derivative and warrant liability. As of December 31, 2013, the 2014 Warrant liability was reported on the balance sheet in derivative and warrant liability. Upon closing of the IPO in April 2015, the 2013 Warrant liability was marked to fair value and then reclassified to equity. The Company used a Monte Carlo simulation to value the Underwriter Warrant liability and the embedded Put Option at December 31, 2014 and September 30, 2015. The Company used a Monte Carlo simulation to value the 2013 Warrant liability as of December 31, 2014, and the closing date of the IPO. Significant unobservable inputs used in measuring the fair value of these financial instruments included the Company’s estimated enterprise value, an estimate of the timing of a liquidity event, a present value discount rate and an estimate of the Company’s stock volatility using the volatilities of guideline peer companies. Changes in the fair value of the Underwriter Warrant liability, the 2013 Warrant liability, the Deerfield Warrant liability and the embedded Put Option are reflected in the statements of operations as a fair value adjustment. A 10% increase in the enterprise value would result in an increase of $1.0 million in the estimated fair value of the Underwriter Warrant liability, an increase of $3.6 million in the estimated fair value of the Deerfield Warrant liability, and no change in the estimated fair value of the embedded Put Option at September 30, 2015.

A reconciliation of the beginning and ending balances for the derivative and warrant liability measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is as follows (in thousands):


	Nine Months Ended September 30,
	2014		2015
Balance at beginning of period	$	2,812	$	15,966
Issuance of Deerfield Warrant		7,610		–
Embedded Put Option		220		–
Conversion of 2013 Convertible Notes		(1,900)		–
Reclassification of 2013 Warrants to equity		–		(1,110)
Exercise of warrants		–		(271)
Adjustment to fair value		4,002		26,512

Balance at end of period	$	12,744	$	41,097

12. Fair Value of Financial Instruments

The fair value of the Company’s 2013 Convertible Notes was $3,650,000 at December 31, 2013. The 2013 Convertible Notes fall within Level 3 of the fair value hierarchy as their value is based on the credit worthiness of the Company, which is an unobservable input. The 2013 Convertible Notes were converted into Series D Preferred on June 2, 2014.

The fair value of the Deerfield Convertible Notes and the Term Notes was $17,350,000 and $9,032,000 at December 31, 2014, respectively. The Deerfield Convertible Notes and Term Notes fall within level 3 of the fair value hierarchy as their value is based on the credit worthiness of the Company, which is an unobservable input.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The Company evaluates its financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in which to classify them for each reporting period. This determination requires significant judgments to be made. The following table summarizes the conclusions reached regarding fair value measurements as of December 31, 2013 and 2014 (in thousands):


	Balance at December 31, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	1,053,260	$	–	$	–	$	1,053,260
Preferred stock warrant liability		400,000		–		–		400,000
Conversion Feature and Put Option		1,360,000		–		–		1,360,000

	$	2,813,260	$	–	$	–	$	2,813,260



	Balance at December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	2,745,891	$	–	$	–	$	2,745,891
Preferred stock warrant liability		13,080,000		–		–		13,080,000
Embedded Deerfield Put Option		140,000		–		–		140,000

	$	15,965,891	$	–	$	–	$	15,965,891

The Company’s Underwriter Warrant liability, preferred stock warrant liability, the Conversion Feature and Put Option on the 2013 Convertible Notes and the Embedded Deerfield Put Option on the Deerfield Warrant are measured at fair value on a recurring basis. As of December 31, 2013, the Underwriter Warrant liability, the preferred stock warrant liability and the Conversion Feature and Put Option are reported on the balance sheet in derivative and warrant liability. As of December 31, 2014, the Underwriter Warrant liability, the preferred stock warrant liability and the Embedded Deerfield Put Option are reported on the balance sheet in derivative and warrant liability. The Company used a Monte Carlo simulation to value the Underwriter Warrant liability and the preferred stock warrant liability at December 31, 2013 and 2014. The Company used a Monte Carlo simulation to value the Conversion Feature and Put Option at issuance and December 31, 2013 and the Embedded Deerfield Put Option at December 31, 2014. Significant unobservable inputs used in measuring the fair value of financial instruments included the Company’s estimated enterprise value, an estimate of the timing of a liquidity event, a present value discount rate, a risk-free rate of interest and an estimate of the Company’s stock volatility using the volatilities of guideline peer companies. Changes in the fair value of the Underwriter Warrant liability, the preferred stock warrant liability and the Conversion Feature and Put Option are reflected in the statements of operations as a fair value adjustment. A 10% increase in the enterprise value would result in a $158,891 increase in the estimated fair value of the Underwriter Warrant liability and a $60,000 increase in the estimated fair value of the preferred stock warrant liability, while an increase of 100 basis points in the discount rate would result in a $610,000 increase in the estimated fair value of the Conversion Feature and Put Option at December 31, 2013. A 10% increase in the enterprise value would result in a $423,477 increase in the estimated fair value of the Underwriter Warrant liability, a $1,694,484 increase in the estimated fair value of the preferred stock warrant liability and no change in the estimated fair value of the Embedded Deerfield Put Option at December 31, 2014.


	2013		2014
Balance at January 1	$	2,390,608	$	2,813,260
Issuance of 2013 Warrants		410,000		–
Issuance of 2013 Convertible Notes		1,150,000		–
Issuance of Deerfield Convertible Notes and Term Notes		–		7,610,000
Embedded Deerfield Put Option		–		220,000
Conversion of 2013 Convertible Notes		–		(1,900,000)
Adjustment to fair value		(1,137,348)		7,222,631

Balance at December 31	$	2,813,260	$	15,965,891

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Concentration of Credit Risk

Income Taxes

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Income Taxes

13. Income Taxes

The Company’s financial statements include a total state tax benefit of $19,544 and $22,247 on a loss before income taxes of $5,245,989 and $24,477,008 for the years ended December 31, 2013 and 2014, respectively. A reconciliation of the difference between the benefit for income taxes and income taxes at the statutory U.S. federal income tax rate is as follows:


	Year Ended December 31,
	2013			2014
Federal statutory rate	$	(1,783,637)	34.0%	$	(8,322,268)	34.0%
Effect of:
Change in valuation allowance		2,013,636	(38.4)		8,047,512	(32.9)
State income taxes		(394,912)	7.5		(1,459,773)	6.0
Underwriter warrant liability		(454,698)	8.7		575,495	(2.4)
State research and development credit		(19,544)	0.4		(22,497)	0.1
Federal research and development credit		(132,681)	2.5		(804,916)	3.3
Preferred stock warrant liability		136,000	(2.6)		1,723,800	(7.0)
Conversion Feature and Put Option on 2013 Convertible Notes		462,400	(8.8)		307,864	(1.3)
Interest expense		51,676	(1.0)		(51,676)	0.2
Other		102,216	(1.9)		(16,038)	0.1

Federal income tax provision effective rate	$	(19,544)	0.4%	$	(22,497)	0.1%

The components of deferred tax assets and liabilities are as follows:


	December 31,
	2013			2014
Deferred tax assets relating to:
Net operating loss carryforwards	$	9,606,253		$	16,389,697
Research and development tax carryforward		898,813			1,792,778
Compensation		75,872			83,377

Total gross deferred tax assets		10,580,938			18,265,852

Deferred tax liabilities relating to:
Property and equipment		175,891			169,469

Total gross deferred tax liabilities		175,891			169,469

Deferred tax assets less liabilities		10,405,047			18,096,383
Valuation allowance		(10,405,047	)		(18,096,383	)

Net deferred tax asset (liability)	$	–		$	–

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. Based upon the level of historical taxable income and projections for future taxable income over the periods in which the deferred tax assets are deductible, management believes it is more likely than not that the Company will not realize the benefits of these deductible differences in the future.

The Company had the following federal net operating loss carryforward and research activities credits as of December 31, 2014:


Year Incurred	Net Operating Loss		Research Activities Credit		Expiration
2007	$	454,280	$	29,977		2027
2008		1,178,096		64,677		2028
2009		3,060,387		175,635		2029
2010		3,423,056		149,246		2030
2011		9,928,651		176,585		2031
2012		–		170,012		2032
2013		4,521,783		132,681		2033
2014		15,801,891		893,965		2034

	$	38,368,144	$	1,792,778

The Company also has certain state net operating loss carryforwards, primarily from Iowa, where $38,289,880 of net operating loss carryforwards exist that expire between 2027 and 2034. Due to potential ownership changes that may have occurred or would occur in the future, IRC Section 382 may place additional limitations on the Company’s ability to utilize the net operating loss carryforward.

Financial Interpretation No. 48 (FIN 48), Accounting for Uncertainty in Income Taxes, uses the term “more likely than not” to evaluate whether or not a tax position will be sustained upon examination. The Company has not identified any tax positions that do not meet the more likely than not threshold.

Net Loss Per Share

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Earnings Per Share [Abstract]

Net Loss Per Share

I. Net Loss Per Share

Under the two-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss as the holders of the participating securities have no obligation to fund losses. Diluted net loss per common share is computed under the two-class method by using the weighted average number of shares of common stock outstanding plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, the Company analyzes the potential dilutive effect of the outstanding participating securities under the if-converted method when calculating diluted earnings per share in which it is assumed that the outstanding participating securities convert or reclassified into common stock at the beginning of the period. The Company reports the more dilutive of the approaches (two-class or if-converted) as its diluted net income per share during the period. Due to the existence of net losses for the nine month periods ended September 30, 2014 and 2015, basic and diluted loss per share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

The following securities, presented on a common stock equivalent basis, have been excluded from the calculation of weighted average common shares outstanding because their effect is anti-dilutive:


	Nine Months Ended September 30,
	2014		2015
Redeemable convertible preferred stock:
Series A		1,293,895		–
Series B		829,333		–
Series C		2,474,322		–
Series D		967,390		–
Series D-1		–		–

Total redeemable convertible preferred stock		5,564,940		–
Warrants to purchase common stock		596,104		2,636,180
Deerfield warrant to purchase Series D Preferred Stock		1,923,077		–
Warrants to purchase Series D Preferred Stock		1,823,827		–
Awards under equity incentive plans		395,200		1,390,438
Deerfield Convertible Notes		1,764,518		1,943,458

Total		12,067,666		5,970,076

14. Net Loss Per Share

Under the two-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss as the holders of the participating securities have no obligation to fund losses. Diluted net loss per common share is computed under the two-class method by using the weighted average number of shares of common stock outstanding plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, the Company analyzes the potential dilutive effect of the outstanding participating securities under the if-converted method when calculating diluted earnings per share in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period. The Company reports the more dilutive of the approaches (two-class or if-converted) as its diluted net income per share during the period. Due to the existence of net losses for the years ended December 31, 2013 and 2014, basic and diluted loss per share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

The following table summarizes the computation of basic and diluted net loss and net loss per share of the Company:


	Year Ended December 31,
	2013		2014
Net loss—basic and diluted	$	(5,226,445)	$	(24,454,761)

Weighted-average number of common shares—basic and diluted		2,381,041		2,381,041

Net loss per share—basic and diluted	$	(2.20)	$	(10.27)

Diluted net loss per share is the same as basic net loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given the Company’s net loss. The following securities, presented on a common stock equivalent basis, have been excluded from the calculation of weighted average common shares outstanding because their effect is anti-dilutive:


	Year Ended December 31,
	2013		2014
Redeemable convertible preferred stock:
Series A		1,293,838		1,293,838
Series B		829,234		829,234
Series C		2,474,121		2,474,121
Series D		–		967,359
Warrants to purchase common stock		595,920		595,920
Warrants to purchase Series D Preferred		143,893		2,066,970
Awards under Incentive Stock Plan		296,255		395,185
2013 Convertible Notes		683,417		–
Deerfield Convertible Notes		–		1,808,353

Pro Forma Net Loss Per Share (unaudited)

The denominator used in computing pro forma net loss per share for the year ended December 31, 2014 has been adjusted to assume the conversion of the principal amount and accrued interest of the 2013 Convertible Notes at the beginning of the period or at the time the interest is accrued and the conversion of all outstanding shares of Preferred Stock into common stock as of the beginning of the year or at the time of issuance, if later. The calculation of pro forma net loss per share is as follows:


	December 31, 2014
Numerator:
Historical net loss	$	(24,454,761)	(a)

Pro forma numerator for basic and diluted loss per share	$	(24,454,761)

Denominator:
Historical denominator for basic and diluted net loss per share—weighted average shares		2,381,041(	b)
Plus: conversion of redeemable convertible preferred stock to common stock		5,162,081(	c)
Plus: conversion of 2013 Convertible Notes		280,230(	d)

Pro forma denominator for basic and diluted net loss per share		7,823,352

Pro forma basic and diluted loss per share	$	(3.13)

(a)	Represents actual net loss.

(b)	Represents actual weighted average common shares outstanding—basic.

(c)	Represents the number of shares of common stock that would have been outstanding had all outstanding shares of the Preferred Stock converted into shares of common stock as of January 1, 2014 or the issuance dates of the Preferred Stock, if later, computed on a weighted average basis.

(d)

Represents the number of shares of common stock that would have been outstanding had the principal amount and accrued interest of the 2013 Convertible Notes converted into shares of common stock at the beginning of the period or at the time the interest is accrued, computed on a weighted average basis.

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2014
Postemployment Benefits [Abstract]
Employee Benefit Plan	15. Employee Benefit Plan The Company has a 401(k) retirement plan (the 401(k) Plan) that covers all employees. The Company may provide a discretionary match with a maximum amount of 4% of the participant’s compensation, which vests immediately. The Company made matching contributions under the 401(k) Plan of $49,901 and $68,513 for the years ended December 31, 2013 and 2014, respectively. The Company has a discretionary profit sharing plan (the Profit Sharing Plan) that covers all employees. Employees become eligible participants in the Profit Sharing Plan once they have provided three years of service to the Company. The Company made no contributions to the Profit Sharing Plan in 2013 or 2014.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events The Company evaluated subsequent events through March 11, 2015, the date on which the December 31, 2014 financial statements were available to be issued. There are no significant events that require disclosure in these financial statements, except as follows: *Issuance of Series D-1 Convertible Preferred Stock* On February 19, 2015, the Company issued and sold 3,200,000 shares of Series D-1 Convertible Preferred Stock at $1.25 per share for an aggregate of $4,000,000. *Grant of Stock Options* On March 2, 2015, the Company granted options to purchase 145,999 shares of common stock at an exercise price of $8.63 per share. The Company updated its evaluation of subsequent events through April 3, 2015, the date on which the December 31, 2014 financial statements were reissued. There are no additional significant events that require disclosure in these financial statements, except as follows: *Reverse Stock Split* On April 2, 2015, the Company amended its amended and restated certificate of incorporation effecting a 1-for-7.5 reverse stock split of its common stock. The reverse stock split did not cause an adjustment to the par value or the authorized shares of the common stock or preferred stock. As a result of the reverse stock split, the Company also adjusted the share and per-share amounts under its Incentive Stock Plan and common stock warrant agreements with third parties. No fractional shares were issued in connection with the reverse stock split. All disclosure of common shares and per-common share data in the accompanying financial statements and related notes have been adjusted retroactively to reflect the reverse stock split for all periods presented.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Use of Estimates

Use of Estimates

Concentration of Credit Risk

Cash and Cash Equivalents

Cash and Cash Equivalents

The Company considers any highly liquid investments with an original maturity of three months or less to be cash and cash equivalents.

Property and Equipment

Property and Equipment

Deferred Offering Costs

Deferred Offering Costs

Debt Issuance Costs

Debt Issuance Costs

Debt issuance costs incurred in connection with financing arrangements are amortized over the life of the respective financing arrangement using the effective interest method.

Supply Arrangements

Supply Arrangements

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Level 1—Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets;

Level 2—Observable inputs other than quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities; and

Level 3—Unobservable inputs that are supported by little or no market data, which require the Company to develop its own assumptions.

Research and Development

Research and Development

Patent Costs

Patent Costs

Patent costs, including related legal costs, are expensed as incurred and recorded within general and administrative expenses on the statement of operations.

Income Taxes

Income Taxes

Stock-Based Compensation

Stock-Based Compensation

Basic and Diluted Net Loss per Share of Common Stock

Basic and Diluted Net Loss per Share of Common Stock

Segment and Geographic Information

Segment and Geographic Information

Application of New or Revised Accounting Standards Adopted

Application of New or Revised Accounting Standards—Adopted

From time to time, the Financial Accounting Standards Board (the FASB) or other standard-setting bodies issue accounting standards that are adopted by the Company as of the specified effective date.

In June 2014, the FASB issued ASU No. 2014-10, Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation (ASU 2014-10). This ASU removes all incremental financial reporting requirements for development stage entities, including the removal of Topic 915 from the FASB Accounting Standards Codification (ASC). The amendments in this ASU eliminate certain disclosure requirements to (1) present inception-to-date information in the statements of income, cash flows and shareholder equity, (2) label the financial statements as those of a development stage entity, (3) disclose a description of the development stage activities in which the entity is engaged and (4) disclose in the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. The ASU clarifies that disclosures about risks and uncertainties required by Topic 275 also apply to entities that have not commenced planned principal operations.

Application of New or Revised Accounting Standards Not Yet Adopted

Application of New or Revised Accounting Standards—Not Yet Adopted

Pro Forma

Unaudited Pro Forma Presentation

Unaudited Pro Forma Presentation

Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2014

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Components of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following:


	December 31,
	2013		2014
Income tax receivable	$	20,427	$	22,415
Leased equipment deposit		41,760		—
Other current assets		8,783		178

Total	$	70,970	$	22,593

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment [Abstract]

Components of Property and Equipment

Property and equipment consists of the following:


	December 31,
	2013		2014
Laboratory equipment	$	537,058	$	530,495
Computers and hardware		56,156		72,691
Furniture and office equipment		105,048		137,235
Leasehold improvements		6,226		6,226

Total property and equipment		704,488		746,647
Less: accumulated depreciation and amortization		(324,285)		(394,453)

Property and equipment, net	$	380,203	$	352,194

Assets under Capital Leases Included in Property and Equipment

The Company leases various equipment under capital lease agreements. The assets under capital leases are included in property and equipment as follows:


	December 31,
	2013		2014
Furniture and office equipment	$	94,388	$	94,388
Less: accumulated depreciation and amortization		(3,146)		(12,585)

	$	91,242	$	81,803

Estimated Useful Lives of Property and Equipment

The estimated useful lives of property and equipment are as follows:


Asset Category		Useful Life (in years)
Laboratory equipment		10
Computers and hardware		5-7
Furniture and office equipment		5-10
Leasehold improvements		10-15

Accounts Payable and Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2014

Payables and Accruals [Abstract]

Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consist of the following:


	December 31,
	2013		2014
Accounts payable	$	386,071	$	1,670,486
Accrued interest		151,989		1,437,846
Accrued banking fees		700,000		700,000
Accrued payroll		127,514		94,723

Total	$	1,365,574	$	3,903,055

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2014

Commitments and Contingencies Disclosure [Abstract]

Future Minimum Lease Payments under Capital Leases

Future minimum lease payments under capital leases and non-cancelable operating leases as of December 31, 2014 were as follows:


Year Ending December 31,	Capital Leases		Operating Leases
2015	$	31,789	$	168,101
2016		26,492		146,923
2017		—		65,494

Total minimum lease payments		58,281	$	380,518

Less: amounts representing interest		(362)

Total	$	57,919

Redeemable Convertible Preferred Stock and Warrants (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Text Block [Abstract]

Summary of Redeemable Convertible Preferred Stock Activity

The following table summarizes redeemable convertible preferred stock activity for the nine months ended September 30, 2015:

Shares of

Series A
Preferred

Series B
Preferred

Series C
Preferred

Series D
Preferred

Series D-1
Preferred

Total

Balance, December 31, 2014

9,704,215

6,220,000

18,557,408

7,255,425

–

41,737,048

Issuance of Series D-1 Preferred Stock

–

3,200,000

Exercise of Series D Preferred Warrants

–

3,205

–

3,205

Less: Conversion of Preferred Stock into Common Stock upon IPO

(9,704,215)

(6,220,000)

(18,557,408)

(7,258,630)

(3,200,000)

(44,940,253)

Balance, September 30, 2015

–


	Authorized		Outstanding		Issue Price		Conversion Price		Liquidation Preference
Series A Preferred		9,705,000		9,704,215	$	0.40	$	3.00	$	3,881,686
Series B Preferred		6,220,000		6,220,000	$	0.62	$	4.65		3,856,400
Series C Preferred		18,558,000		18,557,408	$	0.78	$	5.85		14,474,778
Series D Preferred		75,000,000		7,255,425	$	0.78	$	5.85		5,659,232

Total		109,483,000		41,737,048					$	27,872,096

Preferred Stock Activity

The following table summarizes redeemable convertible preferred stock activity for the years ended December 31, 2013 and 2014:


	Shares of
	Series A Preferred		Series B Preferred		Series C Preferred		Series D Preferred		Total
Balance, January 1, 2013		9,704,215		6,220,000		18,557,408		–		34,481,623

Balance, December 31, 2013		9,704,215		6,220,000		18,557,408		–		34,481,623
Shares issued upon conversion of 2013 Convertible Notes		–		–		–		5,332,348		5,332,348
Shares issued for financing fee to Deerfield		–		–		–		1,923,077		1,923,077

Balance, December 31, 2014		9,704,215		6,220,000		18,557,408		7,255,425		41,737,048

Outstanding Warrants to Purchase

As of December 31, 2014, outstanding warrants to purchase the Company’s Series D Preferred were as follows:


Issuance Date	Number of Underlying Shares		Exercise Price
2013		1,079,453	$	0.78
2014		14,423,076	$	0.78

		15,502,529

Common Stock and Warrants (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Equity [Abstract]

Schedule of Authorized Shares of Common Stock Reserved for Future Issuance

At December 31, 2014 and September 30, 2015, the Company had reserved authorized shares of common stock for future issuance as follows:


	December 31, 2014		September 30, 2015
Conversion of Series A Preferred		1,293,838		–
Conversion of Series B Preferred		829,234		–
Conversion of Series C Preferred		2,474,121		–
Conversion of Series D Preferred		967,359		–
Conversion of Series D-1 Preferred		–		–
Conversion of Deerfield Convertible Notes		1,808,353		1,943,458
Outstanding awards under equity incentive plans		395,185		1,390,438
Outstanding common stock warrants		595,920		2,636,180
Outstanding Series D Preferred warrants		2,066,970		–
Possible future issuances under equity incentive plans		365,706		1,422,498

Total common shares reserved for future issuance		10,796,686		7,392,574

At December 31, 2014, the Company had reserved authorized shares of common stock for future issuance as follows:


	Shares of Common Stock
Conversion of Series A Preferred		1,293,838
Conversion of Series B Preferred		829,234
Conversion of Series C Preferred		2,474,121
Conversion of Series D Preferred		967,359
Conversion of Deerfield Convertible Notes		1,808,353
Outstanding Series D Preferred Warrants		2,066,970
Outstanding awards under Incentive Stock Plan		395,185
Outstanding common stock warrants		595,920
Possible future issuances under Incentive Stock Plan		365,706

Total common shares reserved for future issuance		10,796,686

Schedule of Stockholders' Equity Note, Warrants or Rights

No Underwriter Warrants have been exercised since issuance and, as of December 31, 2014, the Company’s outstanding Underwriter Warrants and related exercise price by issuance were as follows:


Issuance Date	Number of Underlying Shares		Exercise Price
2008/2009		99,929	$	3.90
2009		82,895	$	4.65
2010		112,289	$	5.85
2011		242,911	$	5.85
2012		16,430	$	5.85

		554,454

Schedule of Common Stock Shares Activity

The following table summarizes common stock activity for the nine months ended September 30, 2015:


	Shares of Common Stock
Beginning balance at December 31, 2014		2,381,041
Issuance of common stock in connection with initial public offering		5,854,545
Conversion of preferred stock to common stock in connection with initial public offering		5,980,564
Common stock warrants exercised		24,746
Common stock options exercised		666

Ending balance at September 30, 2015		14,241,562

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Schedule of Stock-Based Compensation Expense

Stock-based compensation expense recorded under the Incentive Stock Plan and the 2014 Plan is included in the following line items in the accompanying statements of operations (in thousands):


	Nine Months Ended September 30,
	2014		2015
Research and development	$	37	$	308
General and administrative		132		1,148

	$	169	$	1,456

Stock-based compensation expense recorded under the Plan is included in the following line items in the accompanying statements of operations:


	Year Ended December 31,
	2013		2014
Research and development	$	29,296	$	61,467
General and administrative		104,449		152,291

	$	133,745	$	213,758

Black-Scholes-Merton Option Pricing Model

The assumptions used to estimate fair value are as follows:


	Year Ended December 31,
	2013	2014
Risk-free interest rate	0.52% - 2.80%	0.91% - 2.70%
Expected term (in years)	4.04 - 10.00	7.00 - 10.00
Expected volatility	58.55% - 92.00%	86.00% - 95.00%
Expected dividend yield	0%	0%

Schedule of Stock Option Activity

The activity under the Plan for the year ended December 31, 2014 is summarized as follows:


	Number of Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Outstanding balance at January 1, 2014		296,256	$	5.24		7.24	$	–
Granted		112,262	$	5.85
Exercised		–		–
Cancelled		(13,333)	$	5.85

Outstanding balance at December 31, 2014		395,185	$	5.40		7.24	$	1,275,980

Exercisable at December 31, 2014		170,167	$	4.80		5.71	$	651,543

Vested and expected to vest at December 31, 2014		297,899	$	5.25		6.47	$	1,006,008

Information Regarding Currently Outstanding and Exercisable Options

Information regarding currently outstanding and exercisable options as of December 31, 2014 is as follows:


	Options Outstanding			Options Exercisable
Exercise Price	Number of Shares		Weighted- Average Remaining Contractual Term (in years)	Number of Shares		Weighted- Average Remaining Contractual Term (in years)
$0.75		12,000	2.50		12,000	2.50
$3.00		20,667	3.54		20,667	3.54
$4.65		49,327	3.61		49,327	3.61
$5.85		313,191	8.24		88,173	7.82

		395,185	7.24		170,167	5.71

Unvested Stock Options

Unvested stock options as of December 31, 2013 and 2014 were as follows:


	Number of Unvested Shares As of December 31,
Exercise Price	2013		2014
$5.85		161,511		225,018

		161,511		225,018

Fair Value of Financial Instruments (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table summarizes the conclusions reached regarding fair value measurements as of December 31, 2014, and September 30, 2015 (in thousands):


	Balance at December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	2,746	$	–	$	–	$	2,746
2013 Warrant liability		520		–		–		520
Deerfield Warrant liability		12,560		–		–		12,560
Embedded Put Option		140		–		–		140

	$	15,966	$	–	$	–	$	15,966


	Balance at September 30, 2015		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	7,674	$	–	$	–	$	7,674
Deerfield Warrant liability		32,615		–		–		32,615
Embedded Put Option		808		–		–		808

	$	41,097	$	–	$	–	$	41,097

The following table summarizes the conclusions reached regarding fair value measurements as of December 31, 2013 and 2014 (in thousands):


	Balance at December 31, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	1,053,260	$	–	$	–	$	1,053,260
Preferred stock warrant liability		400,000		–		–		400,000
Conversion Feature and Put Option		1,360,000		–		–		1,360,000

	$	2,813,260	$	–	$	–	$	2,813,260



	Balance at December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Underwriter Warrant liability	$	2,745,891	$	–	$	–	$	2,745,891
Preferred stock warrant liability		13,080,000		–		–		13,080,000
Embedded Deerfield Put Option		140,000		–		–		140,000

	$	15,965,891	$	–	$	–	$	15,965,891

Reconciliation of Beginning and Ending Balances for Derivative and Warrant Liability Measured at Fair Value on Recurring Basis


	Nine Months Ended September 30,
	2014		2015
Balance at beginning of period	$	2,812	$	15,966
Issuance of Deerfield Warrant		7,610		–
Embedded Put Option		220		–
Conversion of 2013 Convertible Notes		(1,900)		–
Reclassification of 2013 Warrants to equity		–		(1,110)
Exercise of warrants		–		(271)
Adjustment to fair value		4,002		26,512

Balance at end of period	$	12,744	$	41,097


	2013		2014
Balance at January 1	$	2,390,608	$	2,813,260
Issuance of 2013 Warrants		410,000		–
Issuance of 2013 Convertible Notes		1,150,000		–
Issuance of Deerfield Convertible Notes and Term Notes		–		7,610,000
Embedded Deerfield Put Option		–		220,000
Conversion of 2013 Convertible Notes		–		(1,900,000)
Adjustment to fair value		(1,137,348)		7,222,631

Balance at December 31	$	2,813,260	$	15,965,891

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of Difference Between Benefit for Income Taxes and Income Taxes at Statutory U.S Federal Income Tax Rate

A reconciliation of the difference between the benefit for income taxes and income taxes at the statutory U.S. federal income tax rate is as follows:


	Year Ended December 31,
	2013			2014
Federal statutory rate	$	(1,783,637)	34.0%	$	(8,322,268)	34.0%
Effect of:
Change in valuation allowance		2,013,636	(38.4)		8,047,512	(32.9)
State income taxes		(394,912)	7.5		(1,459,773)	6.0
Underwriter warrant liability		(454,698)	8.7		575,495	(2.4)
State research and development credit		(19,544)	0.4		(22,497)	0.1
Federal research and development credit		(132,681)	2.5		(804,916)	3.3
Preferred stock warrant liability		136,000	(2.6)		1,723,800	(7.0)
Conversion Feature and Put Option on 2013 Convertible Notes		462,400	(8.8)		307,864	(1.3)
Interest expense		51,676	(1.0)		(51,676)	0.2
Other		102,216	(1.9)		(16,038)	0.1

Federal income tax provision effective rate	$	(19,544)	0.4%	$	(22,497)	0.1%

Components of Net Deferred Tax Assets and Liabilities

The components of deferred tax assets and liabilities are as follows:


	December 31,
	2013			2014
Deferred tax assets relating to:
Net operating loss carryforwards	$	9,606,253		$	16,389,697
Research and development tax carryforward		898,813			1,792,778
Compensation		75,872			83,377

Total gross deferred tax assets		10,580,938			18,265,852

Deferred tax liabilities relating to:
Property and equipment		175,891			169,469

Total gross deferred tax liabilities		175,891			169,469

Deferred tax assets less liabilities		10,405,047			18,096,383
Valuation allowance		(10,405,047	)		(18,096,383	)

Net deferred tax asset (liability)	$	–		$	–

Federal Net Operating Loss Carryforward And Research Activities Credits

The Company had the following federal net operating loss carryforward and research activities credits as of December 31, 2014:


Year Incurred	Net Operating Loss		Research Activities Credit		Expiration
2007	$	454,280	$	29,977		2027
2008		1,178,096		64,677		2028
2009		3,060,387		175,635		2029
2010		3,423,056		149,246		2030
2011		9,928,651		176,585		2031
2012		–		170,012		2032
2013		4,521,783		132,681		2033
2014		15,801,891		893,965		2034

	$	38,368,144	$	1,792,778

Net Loss Per Share (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Earnings Per Share [Abstract]

Computation of Basic and Diluted Net Loss and Net Loss Per Share

The following table summarizes the computation of basic and diluted net loss and net loss per share of the Company:


	Year Ended December 31,
	2013		2014
Net loss—basic and diluted	$	(5,226,445)	$	(24,454,761)

Weighted-average number of common shares—basic and diluted		2,381,041		2,381,041

Net loss per share—basic and diluted	$	(2.20)	$	(10.27)

Schedule of Anti-dilutive Securities Excluded from Calculation of Weighted Average Common Shares Outstanding

The following securities, presented on a common stock equivalent basis, have been excluded from the calculation of weighted average common shares outstanding because their effect is anti-dilutive:


	Nine Months Ended September 30,
	2014		2015
Redeemable convertible preferred stock:
Series A		1,293,895		–
Series B		829,333		–
Series C		2,474,322		–
Series D		967,390		–
Series D-1		–		–

Total redeemable convertible preferred stock		5,564,940		–
Warrants to purchase common stock		596,104		2,636,180
Deerfield warrant to purchase Series D Preferred Stock		1,923,077		–
Warrants to purchase Series D Preferred Stock		1,823,827		–
Awards under equity incentive plans		395,200		1,390,438
Deerfield Convertible Notes		1,764,518		1,943,458

Total		12,067,666		5,970,076

The following securities, presented on a common stock equivalent basis, have been excluded from the calculation of weighted average common shares outstanding because their effect is anti-dilutive:


	Year Ended December 31,
	2013		2014
Redeemable convertible preferred stock:
Series A		1,293,838		1,293,838
Series B		829,234		829,234
Series C		2,474,121		2,474,121
Series D		–		967,359
Warrants to purchase common stock		595,920		595,920
Warrants to purchase Series D Preferred		143,893		2,066,970
Awards under Incentive Stock Plan		296,255		395,185
2013 Convertible Notes		683,417		–
Deerfield Convertible Notes		–		1,808,353

Calculation of Pro Forma Per Share

The calculation of pro forma net loss per share is as follows:


	December 31, 2014
Numerator:
Historical net loss	$	(24,454,761)	(a)

Pro forma numerator for basic and diluted loss per share	$	(24,454,761)

Denominator:
Historical denominator for basic and diluted net loss per share—weighted average shares		2,381,041(	b)
Plus: conversion of redeemable convertible preferred stock to common stock		5,162,081(	c)
Plus: conversion of 2013 Convertible Notes		280,230(	d)

Pro forma denominator for basic and diluted net loss per share		7,823,352

Pro forma basic and diluted loss per share	$	(3.13)

(a)	Represents actual net loss.

(b)	Represents actual weighted average common shares outstanding—basic.

(c)	Represents the number of shares of common stock that would have been outstanding had all outstanding shares of the Preferred Stock converted into shares of common stock as of January 1, 2014 or the issuance dates of the Preferred Stock, if later, computed on a weighted average basis.

(d)

Description of Business and Basis of Presentation - Additional Information (Detail)		1 Months Ended		9 Months Ended	12 Months Ended
	May 30, 2014 USD ($) $ / shares shares	May 31, 2015 USD ($) $ / shares shares	Apr. 30, 2015 $ / shares shares	Sep. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	May 30, 2015 $ / shares shares	Dec. 31, 2013 $ / shares shares	Jul. 15, 2011 $ / shares shares	Jun. 18, 2008 $ / shares shares
Class Of Stock [Line Items]
Common stock, shares authorized	140,000,000		250,000,000	250,000,000	140,000,000	140,000,000	85,000,000	85,000,000	50,000,000
Common stock, par value \| $ / shares	$ 0.0001			$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0000	$ 0	$ 0
Preferred stock, shares authorized	109,483,000			10,000,000	10,000,000
Preferred stock, par value \| $ / shares	$ 0.0001			$ 0.0001	$ 0.0001
Adjustment for change in par value \| $	$ 1,438,064
Reverse stock split, description				1-for-7.5 reverse stock split	1-for-7.5 reverse stock split
Reverse stock split			0.13
Proceeds from initial public offering, net of underwriting discounts and commissions \| $				$ 59,892,000
Number of preferred shares converted to common shares					5,332,348
Common stock
Class Of Stock [Line Items]
Adjustment for change in par value \| $					$ (1,438,064)
IPO
Class Of Stock [Line Items]
Common stock, shares authorized		250,000,000
Common stock, par value \| $ / shares		$ 0.0001
Preferred stock, shares authorized		10,000,000
Preferred stock, par value \| $ / shares		$ 0.0001
Number of shares of common stock sold			5,090,909
Common stock, price per share \| $ / shares		$ 11.00	$ 11.00
Additional number of common stock sold		763,636
Proceeds from initial public offering, net of underwriting discounts and commissions \| $		$ 59,900,000
Underwriting discounts and commissions \| $		4,500,000
IPO offering expenses \| $		$ 2,800,000
IPO \| Common stock
Class Of Stock [Line Items]
Number of shares of common stock sold				5,854,545
Number of preferred shares converted to common shares		5,980,564	5,980,564	5,980,564

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015
Accounting Policies [Abstract]
Asset impairment charges	$ 0	$ 0
Uncertain tax positions	0		$ 0
Debt issuance costs, net	$ 1,467,959		$ 1,215,000
Minimum
Accounting Policies [Abstract]
Property and equipment, useful lives	5 years
Maximum
Accounting Policies [Abstract]
Property and equipment, useful lives	15 years
Other Long Term Assets
Accounting Policies [Abstract]
Deferred offering costs	$ 1,500,000	$ 0
Pro Forma
Accounting Policies [Abstract]
Debt issuance costs, net	$ 1,467,959
IPO \| Pro Forma
Accounting Policies [Abstract]
Common stock, issued upon conversion	5,564,552

Prepaid Expenses and Other Current Assets - Components of Prepaid Expenses and Other Current Assets (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Prepaid Expense and Other Assets, Current [Abstract]
Income tax receivable		$ 22,415	$ 20,427
Leased equipment deposit			41,760
Other current assets		178	8,783
Total	$ 607,000	$ 22,593	$ 70,970

Property and Equipment - Components of Property and Equipment (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 746,647	$ 704,488
Less: accumulated depreciation and amortization		(394,453)	(324,285)
Property and equipment, net	$ 386,000	352,194	380,203
Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross		530,495	537,058
Computers and Hardware
Property, Plant and Equipment [Line Items]
Property and equipment, gross		72,691	56,156
Furniture and Office Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross		137,235	105,048
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 6,226	$ 6,226

Property and Equipment - Assets under Capital Leases Included in Property and Equipment (Detail) - USD ($)	Dec. 31, 2014	Dec. 31, 2013
Capital Leases, Balance Sheet, Assets by Major Class, Net [Abstract]
Furniture and office equipment	$ 94,388	$ 94,388
Less: accumulated depreciation and amortization	(12,585)	(3,146)
Capital Leases, Balance Sheet, Assets by Major Class, Net, Total	$ 81,803	$ 91,242

Property and Equipment - Estimated Useful Lives of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2014
Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	10 years
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	5 years
Minimum \| Computers and Hardware
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	5 years
Minimum \| Furniture and Office Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	5 years
Minimum \| Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	10 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	15 years
Maximum \| Computers and Hardware
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	7 years
Maximum \| Furniture and Office Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	10 years
Maximum \| Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, useful lives	15 years

Property and Equipment - Additional Information (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 61,000	$ 56,000	$ 74,763	$ 67,724

Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Detail) - USD ($)	Dec. 31, 2014	Dec. 31, 2013
Payables and Accruals [Abstract]
Accounts payable	$ 1,670,486	$ 386,071
Accrued interest	1,437,846	151,989
Accrued banking fees	700,000	700,000
Accrued payroll	94,723	127,514
Total	$ 3,903,055	$ 1,365,574

Debt Obligations - Convertible Notes - Additional Information (Detail) - USD ($)	5 Months Ended	9 Months Ended	12 Months Ended
	Oct. 31, 2013	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
fair value of Conversion Feature		$ 220,000	$ 220,000
Embedded Put Option
Debt Instrument [Line Items]
fair value of Conversion Feature	$ 1,150,000		$ 0	$ 1,360,000
Unsecured Convertible Promissory Notes
Debt Instrument [Line Items]
Convertible notes, interest rate	10.00%
Gross proceeds from issuance of convertible notes	$ 3,846,000
Terms of Conversion Feature			The principal amount and accrued interest of the 2013 Convertible Notes automatically convert (the Conversion Feature) into subsequently issued equity securities if the Company issues equity securities in a transaction or series of related transactions that result in aggregate gross proceeds to the Company of at least $7,500,000 (a Qualified Financing).
Unsecured Convertible Promissory Notes \| Minimum proceeds that triggers automatic conversion
Debt Instrument [Line Items]
Aggregate gross proceeds from equity			$ 7,500,000
Unsecured Convertible Promissory Notes \| 2013 Warrants
Debt Instrument [Line Items]
Warrants issued				1,079,453

Debt Obligations - Deerfield Facility Agreement - Additional Information (Detail) - USD ($)		9 Months Ended	12 Months Ended
	Jun. 02, 2014	Sep. 30, 2015	Dec. 31, 2014	Apr. 30, 2015	Dec. 31, 2013
IPO
Debt Instrument [Line Items]
Reclassification of common stock shares	256,410
Third Tranche
Debt Instrument [Line Items]
Weighted average sales price		115.00%	115.00%
Fourth Tranche
Debt Instrument [Line Items]
Weighted average sales price		115.00%	115.00%
Deerfield Warrant
Debt Instrument [Line Items]
Warrants expiration date	Jun. 02, 2024
Deerfield Warrant \| IPO
Debt Instrument [Line Items]
Preferred stock called by warrants	1,923,077
Warrant, exercise price	$ 5.85
Series D Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Preferred stock called by warrants		1,079,453	15,502,529	15,499,324	1,079,453
Warrant, exercise price			$ 0.78
Deerfield Convertible Notes
Debt Instrument [Line Items]
Terms of Conversion Feature			Deerfield may convert all or any portion of the outstanding principal and any accrued but unpaid interest on the Deerfield Convertible Notes into shares of Series D Preferred at an initial conversion price of $0.78 per share. At its option, the Company may convert the outstanding principal and accrued interest under the Deerfield Convertible Notes into shares of Series D Preferred at an initial conversion price of $0.78 per share if either of the following occurs prior to June 30, 2016: (i) the FDA has approved, without requiring the performance of an efficacy study, the NDA for KP201/APAP for the treatment of acute pain; or (ii) the FDA has accepted the NDA for KP201/APAP for review and a qualified IPO, as defined in the Deerfield Facility Agreement, has occurred
Conversion price	$ 5.85
Deerfield Convertible Notes \| Series D Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion price			$ 0.78
Deerfield Facility Agreement
Debt Instrument [Line Items]
Line of credit agreement, maximum borrowing capacity	$ 60,000,000
Facility agreement, interest rate	9.75%
Facility agreement, repayment description		The Company must repay one-third of the outstanding principal amount of all debt issued under the Deerfield Facility Agreement on the fourth and fifth anniversaries of the Deerfield Facility Agreement. The Company is then obligated to repay the balance of the outstanding principal amount on February 14, 2020.	The Company must repay one-third of the outstanding principal amount of all debt issued under the Deerfield Facility Agreement on the fourth and fifth anniversaries of the Deerfield Facility Agreement. The Company is then obligated to repay the balance of the outstanding principal amount on February 14, 2020.
Facility agreement, repayment period		Feb. 14, 2020	Feb. 14, 2020
Line of Credit Interest Payment, Due Date		Jul. 01, 2016	Jul. 01, 2016
Line of credit agreement, available borrowing capacity		$ 35,000,000	$ 35,000,000
Deerfield Facility Agreement \| Second Tranche
Debt Instrument [Line Items]
Facility agreement, interest rate		9.75%	9.75%
Preferred stock called by warrants		1,282,052
Warrant, exercise price		$ 5.85
Line of credit agreement, available borrowing capacity		$ 10,000,000	$ 10,000,000
Deerfield Facility Agreement \| Third Tranche
Debt Instrument [Line Items]
Facility agreement, interest rate		9.75%	9.75%
Line of credit agreement, available borrowing capacity		$ 12,500,000	$ 12,500,000
Warrants exercisable as percentage of principal amount of debt disbursed		60.00%	60.00%
Consecutive trading days, threshold for warrant exercise		20 days	20 days
Deerfield Facility Agreement \| Fourth Tranche
Debt Instrument [Line Items]
Facility agreement, interest rate		9.75%	9.75%
Line of credit agreement, available borrowing capacity		$ 12,500,000	$ 12,500,000
Warrants exercisable as percentage of principal amount of debt disbursed		60.00%	60.00%
Consecutive trading days, threshold for warrant exercise		20 days	20 days
Deerfield Facility Agreement \| Put Option
Debt Instrument [Line Items]
Fair value of embedded put option	$ 220,000
Deerfield Facility Agreement \| Deerfield Warrant
Debt Instrument [Line Items]
Warrant, exercise price	$ 0.78
Warrants expiration date	Jun. 02, 2024
Fair value of warrants	$ 7,610,000
Deerfield Facility Agreement \| Series D Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Preferred stock called by warrants	14,423,076
Shares issued as consideration for loans provided	1,923,077
Fair value of preferred shares	$ 1,500,000
Deerfield Facility Agreement \| Series D Redeemable Convertible Preferred Stock \| Second Tranche
Debt Instrument [Line Items]
Preferred stock called by warrants			9,615,385
Warrant, exercise price			$ 0.78
Deerfield Facility Agreement \| Term Notes
Debt Instrument [Line Items]
Facility agreement	15,000,000
Deerfield Facility Agreement \| Deerfield Convertible Notes
Debt Instrument [Line Items]
Facility agreement	$ 10,000,000

Debt Obligations - Conversion of 2013 Convertible Notes into Series D Preferred - Additional Information (Detail) - USD ($)		5 Months Ended	9 Months Ended	12 Months Ended
	Jun. 02, 2014	Oct. 31, 2013	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Accrued interest				$ 1,437,846	$ 151,989
Gain on extinguishment of debt			$ 1,900,000	$ 1,900,000
Unsecured Convertible Promissory Notes
Debt Instrument [Line Items]
Outstanding principal balance of convertible notes	$ 3,846,000
Accrued interest	313,232
Gain on extinguishment of debt	$ 1,900,000
Convertible notes, interest rate		10.00%
Gross proceeds from issuance of convertible notes		$ 3,846,000
Unsecured Convertible Promissory Notes \| Series D Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion price	$ 0.78
Shares issued on conversion of convertible notes	5,332,348

Debt Obligations - Line of Credit - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Line of credit	$ 50,000	$ 50,000		$ 15,155
Line of Credit Agreement
Debt Instrument [Line Items]
Line of credit, basis spread on variable rate	1.75%	1.75%
Line of credit, description of variable rate basis	Prime rate plus 1.75% per annum	Prime rate plus 1.75% per annum
Convertible notes, interest rate	5.00%	5.00%	5.00%	5.00%

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

Net loss-basic and diluted

Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Renewal option extend lease an additional year	3 years
Interest rate for assets under remaining capital leases	0.65%
Rent expense for non-cancelable operating leases	$ 193,372	$ 144,896
IOWA
Loss Contingencies [Line Items]
Lease facilities expires date	Sep. 30, 2016
FLORIDA
Loss Contingencies [Line Items]
Lease facilities expires date	Oct. 31, 2017

Commitments and Contingencies - Future Minimum Lease Payments under Capital Leases and Non-Cancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2014 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2015	$ 31,789
2016	26,492
2017	0
Total minimum lease payments	58,281
Less: amounts representing interest	(362)
Total	57,919
2015	168,101
2016	146,923
2017	65,494
Total minimum lease payments	$ 380,518

Supply Arrangement - Additional Information (Detail)	Dec. 31, 2014 Agreement
Commitments and Contingencies Disclosure [Abstract]
Number of manufacturing arrangement	1

Redeemable Convertible Preferred Stock and Warrants - Authorized, Issued, and Outstanding Redeemable Convertible Preferred Stock - Additional Information (Detail) - $ / shares	1 Months Ended		9 Months Ended	12 Months Ended
	May 31, 2015	Apr. 30, 2015	Sep. 30, 2015	Dec. 31, 2014	May 30, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 18, 2008
Temporary Equity [Line Items]
Preferred stock, shares authorized			10,000,000	10,000,000	109,483,000
Preferred stock, par value			$ 0.0001	$ 0.0001	$ 0.0001
Redeemable convertible preferred stock, shares authorized		10,000,000		109,483,000				25,000,000
Redeemable convertible preferred stock, par value		$ 0.0001						$ 0
Redeemable convertible preferred stock, shares outstanding			0	41,737,048		34,481,623	34,481,623
Number of preferred shares converted to common shares				5,332,348
Undesignated Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized			10,000,000
Redeemable convertible preferred stock, shares outstanding			0
IPO
Temporary Equity [Line Items]
Preferred stock, shares authorized	10,000,000
Preferred stock, par value	$ 0.0001
Common stock \| IPO
Temporary Equity [Line Items]
Number of preferred shares converted to common shares	5,980,564	5,980,564	5,980,564

Redeemable Convertible Preferred Stock and Warrants - Summary of Authorized, Issued and Outstanding of Convertible Preferred Stock (Detail) - USD ($)	Sep. 30, 2015	Apr. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 15, 2011	Jul. 15, 2010	Apr. 22, 2009	Jun. 18, 2008
Convertible Preferred Stock [Line Items]
Authorized		10,000,000	109,483,000						25,000,000
Outstanding	0		41,737,048	34,481,623	34,481,623
Liquidation Preference			$ 27,872,096
Series A Redeemable Convertible Preferred Stock
Convertible Preferred Stock [Line Items]
Authorized	0		9,705,000	10,000,000					10,000,000
Outstanding	0		9,704,215	9,704,215	9,704,215
Issue Price			$ 0.40
Conversion Price			$ 3.00
Liquidation Preference			$ 3,881,686
Series B Redeemable Convertible Preferred Stock
Convertible Preferred Stock [Line Items]
Authorized	0		6,220,000	7,000,000				7,000,000
Outstanding	0		6,220,000	6,220,000	6,220,000
Issue Price			$ 0.62
Conversion Price			$ 4.65
Liquidation Preference			$ 3,856,400
Series C Redeemable Convertible Preferred Stock
Convertible Preferred Stock [Line Items]
Authorized	0		18,558,000	33,000,000		33,000,000	18,000,000
Outstanding	0		18,557,408	18,557,408	18,557,408
Issue Price			$ 0.78
Conversion Price			$ 5.85
Liquidation Preference			$ 14,474,778
Series D Redeemable Convertible Preferred Stock
Convertible Preferred Stock [Line Items]
Authorized	0		75,000,000	0
Outstanding	0		7,255,425	0	0
Issue Price			$ 0.78
Conversion Price			$ 5.85
Liquidation Preference			$ 5,659,232

Redeemable Convertible Preferred Stock and Warrants - Summary of Redeemable Convertible Preferred Stock Activity (Detail) - shares		9 Months Ended	12 Months Ended
	Jun. 02, 2014	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2009
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		41,737,048	34,481,623
Shares issued upon conversion of 2013 Convertible Notes			5,332,348
Redeemable convertible preferred stock, issuance of Series D-1 Preferred Stock		3,200,000
Shares issued for financing fee to Deerfield			1,923,077
Redeemable convertible preferred stock, exercise of Series D Preferred warrants		3,205
Less: Conversion of Preferred Stock into Common Stock upon IPO		(44,940,253)
Redeemable convertible preferred stock, shares outstanding, ending balance		0	41,737,048
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		9,704,215	9,704,215
Shares issued upon conversion of 2013 Convertible Notes			0	2,204,215
Shares issued for financing fee to Deerfield			0
Less: Conversion of Preferred Stock into Common Stock upon IPO		(9,704,215)
Redeemable convertible preferred stock, shares outstanding, ending balance		0	9,704,215
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		6,220,000	6,220,000
Shares issued upon conversion of 2013 Convertible Notes			0
Shares issued for financing fee to Deerfield			0
Less: Conversion of Preferred Stock into Common Stock upon IPO		(6,220,000)
Redeemable convertible preferred stock, shares outstanding, ending balance		0	6,220,000
Series C Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		18,557,408	18,557,408
Shares issued upon conversion of 2013 Convertible Notes			0
Shares issued for financing fee to Deerfield			0
Less: Conversion of Preferred Stock into Common Stock upon IPO		(18,557,408)
Redeemable convertible preferred stock, shares outstanding, ending balance		0	18,557,408
Series D Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		7,255,425	0
Shares issued upon conversion of 2013 Convertible Notes	5,332,348		5,332,348
Shares issued for financing fee to Deerfield	1,923,077		1,923,077
Redeemable convertible preferred stock, exercise of Series D Preferred warrants		3,205
Less: Conversion of Preferred Stock into Common Stock upon IPO		(7,258,630)
Redeemable convertible preferred stock, shares outstanding, ending balance		0	7,255,425
Series D-1 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		0
Redeemable convertible preferred stock, issuance of Series D-1 Preferred Stock		3,200,000
Less: Conversion of Preferred Stock into Common Stock upon IPO		(3,200,000)
Redeemable convertible preferred stock, shares outstanding, ending balance		0	0

Redeemable Convertible Preferred Stock and Warrants - Series A Redeemable Convertible Preferred Stock (Series A Preferred) - Additional Information (Detail) - USD ($)		12 Months Ended
	Jun. 23, 2008	Dec. 31, 2014	Dec. 31, 2009	Sep. 30, 2015	May 30, 2015	Apr. 30, 2015	May 30, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 15, 2011	Jun. 18, 2008
Temporary Equity [Line Items]
Common and preferred stock, shares authorized											75,000,000
Common stock, shares authorized		140,000,000		250,000,000	140,000,000	250,000,000	140,000,000	85,000,000		85,000,000	50,000,000
Common stock, par value		$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0000		$ 0	$ 0
Redeemable convertible preferred stock, shares authorized		109,483,000				10,000,000					25,000,000
Redeemable convertible preferred stock, par value						$ 0.0001					$ 0
Conversion of stock, shares		5,332,348
Private Placement
Temporary Equity [Line Items]
Issuance of warrants to purchase shares of common stock		554,454							595,920
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		9,705,000		0				10,000,000			10,000,000
Redeemable convertible preferred stock, par value		$ 0.0001		$ 0.0001				$ 0.0001
Issuance of shares, per share amount		$ 0.40
Gross proceeds of private placement offering	$ 3,000,000
Net proceeds from private placement	$ 2,596,243
Conversion of stock, shares		0	2,204,215
Series A Redeemable Convertible Preferred Stock \| Private Placement
Temporary Equity [Line Items]
Issuance of shares	7,500,000
Issuance of shares, per share amount	$ 0.40
Issuance of warrants to purchase shares of common stock	99,929
Issuance of warrants to purchase shares of common stock, per share	$ 3.90
Deferred offering costs	$ 403,757

Redeemable Convertible Preferred Stock and Warrants - Series B Redeemable Convertible Preferred Stock (Series B Preferred) - Additional Information (Detail) - USD ($)	Apr. 22, 2009	Sep. 30, 2015	Apr. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 18, 2008
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized			10,000,000	109,483,000			25,000,000
Redeemable convertible preferred stock, par value			$ 0.0001				$ 0
Private Placement
Temporary Equity [Line Items]
Issuance of warrants to purchase shares of common stock				554,454		595,920
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	7,000,000	0		6,220,000	7,000,000
Redeemable convertible preferred stock, par value	$ 0	$ 0.0001		$ 0.0001	$ 0.0001
Issuance of shares, per share amount				$ 0.62
Gross proceeds of private placement offering	$ 3,856,400
Net proceeds from private placement	$ 3,499,065
Series B Redeemable Convertible Preferred Stock \| Private Placement
Temporary Equity [Line Items]
Issuance of shares	6,220,000
Issuance of shares, per share amount	$ 0.62
Issuance of warrants to purchase shares of common stock	82,895
Issuance of warrants to purchase shares of common stock, per share	$ 4.65
Deferred offering costs	$ 357,335

Redeemable Convertible Preferred Stock and Warrants - Series C Redeemable Convertible Preferred Stock (Series C Preferred) - Additional Information (Detail) - USD ($)		12 Months Ended
	Jul. 15, 2010	Dec. 31, 2014	Dec. 31, 2012	Sep. 30, 2015	May 30, 2015	Apr. 30, 2015	May 30, 2014	Dec. 31, 2013	Jul. 15, 2011	Jun. 18, 2008
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		109,483,000				10,000,000				25,000,000
Redeemable convertible preferred stock, par value						$ 0.0001				$ 0
Common stock, par value		$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0000	$ 0	$ 0
Common stock, shares authorized		140,000,000		250,000,000	140,000,000	250,000,000	140,000,000	85,000,000	85,000,000	50,000,000
Private Placement
Temporary Equity [Line Items]
Issuance of warrants to purchase shares of common stock		554,454	595,920
Series C Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	18,000,000	18,558,000		0				33,000,000	33,000,000
Redeemable convertible preferred stock, par value	$ 0	$ 0.0001		$ 0.0001				$ 0.0001
Issuance of shares, per share amount		$ 0.78
Gross proceeds of private placement offering	$ 4,381,916	$ 9,483,738	$ 674,129
Net proceeds from private placement	$ 3,976,842	$ 8,591,668	$ 525,493
Shares repurchased			83,333
Shares repurchased, per share			$ 0.78
Series C Redeemable Convertible Preferred Stock \| Private Placement
Temporary Equity [Line Items]
Issuance of shares	5,617,835	12,158,638	864,268
Issuance of shares, per share amount	$ 0.78	$ 0.78	$ 0.78
Issuance of warrants to purchase shares of common stock	112,289	242,911	16,430
Issuance of warrants to purchase shares of common stock, per share	$ 5.85	$ 5.85	$ 5.85
Deferred offering costs	$ 405,074	$ 892,070	$ 148,636

Redeemable Convertible Preferred Stock and Warrants - Series D Redeemable Convertible Preferred Stock - Additional Information (Detail) - USD ($)		1 Months Ended	9 Months Ended	12 Months Ended
	Jun. 02, 2014	May 31, 2015	Sep. 30, 2015	Dec. 31, 2014	Apr. 30, 2015	Dec. 31, 2013
Temporary Equity [Line Items]
Conversion of convertible notes, shares				5,332,348
Issuance of Series D Preferred as financing fee				1,923,077
Gross proceeds from IPO			$ 59,892,000
IPO
Temporary Equity [Line Items]
Common stock, price per share		$ 11.00			$ 11.00
Gross proceeds from IPO		$ 59,900,000
IPO \| Minimum
Temporary Equity [Line Items]
Common stock, price per share				$ 9.375
Gross proceeds from IPO				$ 25,000,000
Series D Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares issued			0	7,255,425		0
Common stock, price per share				$ 0.78
Conversion of convertible notes, shares	5,332,348			5,332,348
Issuance of Series D Preferred as financing fee	1,923,077			1,923,077
Shares repurchase description				(1) shares repurchased from former employees, consultants or directors of the Company in accordance with restricted stock purchase agreements with such employees, consultants or directors entered into with approval of the board of directors, (2) the repurchase of up to $100,000 of additional shares, in the aggregate, of such junior or pari passu classes or series of capital stock, and (3) redemptions of the Series D Preferred as expressly authorized in the Certificate of Incorporation
Shares repurchased				100,000

Redeemable Convertible Preferred Stock and Warrants - Warrants (Detail) - Series D Redeemable Convertible Preferred Stock - $ / shares	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2015	Apr. 30, 2015	Dec. 31, 2013
Temporary Equity [Line Items]
Number of Underlying E Shares	15,502,529	1,079,453	15,499,324	1,079,453
xercise Price	$ 0.78
Issuance Date One [Member]
Temporary Equity [Line Items]
Issuance Date	2013
Number of Underlying E Shares	1,079,453
xercise Price	$ 0.78
Issuance Date Two [Member]
Temporary Equity [Line Items]
Issuance Date	2014
Number of Underlying E Shares	14,423,076
xercise Price	$ 0.78

Redeemable Convertible Preferred Stock and Warrants - Warrants - Additional Information (Detail) - USD ($)		9 Months Ended	12 Months Ended
	Jun. 02, 2014	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Jun. 02, 2015	Apr. 30, 2015
Temporary Equity [Line Items]
Redeemable convertible preferred stock, exercise of Series D Preferred warrants		3,205
Convertible Notes
Temporary Equity [Line Items]
Debt instrument issued				$ 3,846,000
2013 Warrants
Temporary Equity [Line Items]
Warrants issued				1,079,453
Warrants expiration date		Jun. 02, 2019	Jun. 02, 2019
Deerfield Warrant
Temporary Equity [Line Items]
Warrants issued	14,423,076
Warrants expiration date	Jun. 02, 2024
Common stock
Temporary Equity [Line Items]
Preferred stock called by warrants				143,466		2,066,543
Warrant, exercise price				$ 5.85
Common stock \| Deerfield Warrant
Temporary Equity [Line Items]
Preferred stock called by warrants					1,923,077
Warrant, exercise price					$ 5.85
Series D Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Preferred stock called by warrants		1,079,453	15,502,529	1,079,453		15,499,324
Redeemable convertible preferred stock, exercise of Series D Preferred warrants		3,205
Warrant, exercise price			$ 0.78

Common Stock and Warrants on Common Stock - Additional Information (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	May 30, 2015	Apr. 30, 2015	May 30, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 15, 2011	Jun. 18, 2008
Class Of Stock [Line Items]
Common stock, shares authorized	250,000,000		140,000,000	140,000,000	250,000,000	140,000,000	85,000,000		85,000,000	50,000,000
Common stock, par value	$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0000		$ 0	$ 0
Common stock, shares issued	14,241,562		2,381,041				2,381,041
Common stock, shares outstanding	14,241,562		2,381,041				2,381,041
Common Stock, Voting Rights			The holders of the common stock have the right to one vote per share of common stock.
Financial liabilities measured at fair value on recurring basis	$ 41,097,000		$ 15,965,891				$ 2,813,260
Common stock warrants exercised	24,746	0
Underwriter Warrant Liability
Class Of Stock [Line Items]
Financial liabilities measured at fair value on recurring basis	$ 7,674,000		$ 2,745,891				$ 1,053,260
Private Placement
Class Of Stock [Line Items]
Common stock called by warrants			554,454					595,920

Common Stocks and Warrants on Common Stock - Schedule of Reserved Authorized Shares of Common Stock for Future Issuance (Detail) - shares	Sep. 30, 2015	Dec. 31, 2014
Class Of Stock [Line Items]
Common shares reserved for future issuance	7,392,574	10,796,686
Series A Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Common shares reserved for future issuance		1,293,838
Series B Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Common shares reserved for future issuance		829,234
Series C Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Common shares reserved for future issuance		2,474,121
Series D Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Common shares reserved for future issuance		967,359
Convertible Notes
Class Of Stock [Line Items]
Common shares reserved for future issuance	1,943,458	1,808,353
Series D Preferred Warrants
Class Of Stock [Line Items]
Common shares reserved for future issuance		2,066,970
Equity Incentive Plans
Class Of Stock [Line Items]
Common shares reserved for future issuance	1,390,438	395,185
Possible Future Issuances Under Equity Incentive Plans
Class Of Stock [Line Items]
Common shares reserved for future issuance	1,422,498	365,706
Common Stock Warrants
Class Of Stock [Line Items]
Common shares reserved for future issuance	2,636,180	595,920

Common Stock and Warrants on Common Stock - Outstanding Underwriter Warrants and Related Exercise Price by Issuance (Detail) - Private Placement - $ / shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2012
Class of Warrant or Right [Line Items]
Common stock called by warrants	554,454	595,920
Issuance Date Three [Member]
Class of Warrant or Right [Line Items]
Issuance Date	2008/2009
Common stock called by warrants	99,929
Exercise Price	$ 3.90
Issuance Date Four [Member]
Class of Warrant or Right [Line Items]
Issuance Date	2009
Common stock called by warrants	82,895
Exercise Price	$ 4.65
Issuance Date Five [Member]
Class of Warrant or Right [Line Items]
Issuance Date	2010
Common stock called by warrants	112,289
Exercise Price	$ 5.85
Issue Date Six [Member]
Class of Warrant or Right [Line Items]
Issuance Date	2011
Common stock called by warrants	242,911
Exercise Price	$ 5.85
Warrants Issue Date Seven [Member]
Class of Warrant or Right [Line Items]
Issuance Date	2012
Common stock called by warrants	16,430
Exercise Price	$ 5.85

Stock-Based Compensation - Additional Information (Detail) - USD ($)	6 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercised		666	0	0	0
Weighted-average fair value of awards granted				$ 4.50	$ 3.00
Total fair value of stock options vested				$ 175,697	$ 173,579
Total unrecognized compensation cost				$ 495,093
Compensation cost recognition weighted-average period				1 year 6 months 22 days
Share option granted				112,262
Stock based compensation expense		$ 1,456,000	$ 169,000	$ 213,758,000	133,745,000
Grant of fully vested stock options				13,333
IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options fully vested and exercisable	134,665
Performance-Based Incentive Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share option granted						80,000
Stock based compensation expense			0	$ 0	$ 0
Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional shares authorized for grant					160,000
Deerfield Agreement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense				$ 62,806
Grant of fully vested stock options				13,333
Common stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional shares authorized for grant					40,000
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense		1,148,000	132,000	$ 152,291,000	$ 104,449,000
General and administrative \| Performance-Based Incentive Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense		700,000
Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense		308,000	$ 37,000	$ 61,467,000	$ 29,296,000
Research and development \| Performance-Based Incentive Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense		$ 100,000
Two Thousand Fourteen Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum number of shares authorized				800,000			666,666
Number of shares available for award				365,706
Percentage of outstanding capital stock				4.00%
Share-based compensation arrangement by share-based payment award, plan modification, description and terms		Number of shares of common stock reserved for issuance under the 2014 Plan will automatically increase on January 1 of each year, beginning on January 1, 2016 and ending on and including January 1, 2024,
Two Thousand Fourteen Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for award		2,266,666
Award option vesting period				3 years
Award option expiration period				10 years
Two Thousand Fourteen Equity Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award option vesting period				1 year
Award option expiration period				7 years

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 1,456	$ 169	$ 213,758	$ 133,745
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	308	37	61,467	29,296
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 1,148	$ 132	$ 152,291	$ 104,449

Stock-Based Compensation - Black-Scholes-Merton Option Pricing Model (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions and Methodology [Line Items]
Risk-free interest rate, minimum	0.91%	0.52%
Risk-free interest rate, maximum	2.70%	2.80%
Expected volatility, minimum	86.00%	58.55%
Expected volatility, maximum	95.00%	92.00%
Expected dividend yield	0.00%	0.00%
Minimum
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions and Methodology [Line Items]
Expected term (in years)	7 years	4 years 15 days
Maximum
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions and Methodology [Line Items]
Expected term (in years)	10 years	10 years

Share-Based Compensation - Schedule of Stock Option Activity (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Shares Under Option
Outstanding balance at January 1, 2014	395,185	296,256	296,256
Granted			112,262
Exercised	(666)	0	0	0
Cancelled			(13,333)
Outstanding balance at December 31, 2014			395,185	296,256
Exercisable at December 31, 2014			170,167
Vested and expected to vest at December 31, 2014			297,899
Weighted Average Exercise Price
Outstanding balance at January 1, 2014	$ 5.40	$ 5.24	$ 5.24
Granted			5.85
Exercised			0
Cancelled			5.85
Outstanding balance at December 31, 2014			5.40	$ 5.24
Exercisable at December 31, 2014			4.80
Vested and expected to vest at December 31, 2014			$ 5.25
Weighted Average Remaining Contractual Term (years)
Outstanding balance			7 years 2 months 27 days	7 years 2 months 27 days
Exercisable at December 31, 2014			5 years 8 months 16 days
Vested and expected to vest at December 31, 2014			6 years 5 months 19 days
Aggregate Intrinsic Value
Outstanding balance at January 1, 2014	$ 1,275,980
Outstanding balance at December 31, 2014			$ 1,275,980
Exercisable at December 31, 2014			651,543
Vested and expected to vest at December 31, 2014			$ 1,006,008

Share-Based Compensation - Information Regarding Currently Outstanding and Exercisable Options (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 0
Options Outstanding, Number of Shares	395,185	296,256
Options Outstanding Weighted- Average Remaining Contractual Term (in years)	7 years 2 months 27 days	7 years 2 months 27 days
Options Exercisable Number of Shares	170,167
Options Exercisable Weighted- Average Remaining Contractual Term (in years)	5 years 8 months 16 days
0.75
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 0.75
Options Outstanding, Number of Shares	12,000
Options Outstanding Weighted- Average Remaining Contractual Term (in years)	2 years 6 months
Options Exercisable Number of Shares	12,000
Options Exercisable Weighted- Average Remaining Contractual Term (in years)	2 years 6 months
3.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 3.00
Options Outstanding, Number of Shares	20,667
Options Outstanding Weighted- Average Remaining Contractual Term (in years)	3 years 6 months 15 days
Options Exercisable Number of Shares	20,667
Options Exercisable Weighted- Average Remaining Contractual Term (in years)	3 years 6 months 15 days
4.65
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 4.65
Options Outstanding, Number of Shares	49,327
Options Outstanding Weighted- Average Remaining Contractual Term (in years)	3 years 7 months 10 days
Options Exercisable Number of Shares	49,327
Options Exercisable Weighted- Average Remaining Contractual Term (in years)	3 years 7 months 10 days
5.85
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 5.85
Options Outstanding, Number of Shares	313,191
Options Outstanding Weighted- Average Remaining Contractual Term (in years)	3 years 7 months 10 days
Options Exercisable Number of Shares	88,173
Options Exercisable Weighted- Average Remaining Contractual Term (in years)	7 years 9 months 26 days

Share-Based Compensation - Nonvested Restricted Stock Unit Awards (Detail) - shares	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Unvested Shares	225,018	161,511
5.85
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Unvested Shares	225,018	161,511

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of financial instruments	$ 41,097,000	$ 12,744,000	$ 15,965,891	$ 2,813,260	$ 2,390,608
Increase in estimated fair value	$ 26,512,000	$ 4,002,000	$ 7,222,631	$ (1,137,348)
Changes in Fair Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Percentage of increase in enterprise value	10.00%		10.00%	10.00%
Percentage of increase in basis points discount rate				1.00%
Underwriter Warrant Liability \| Changes in Fair Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Increase in estimated fair value	$ 1,000,000		$ 423,477	$ 158,891
Deerfield Warrant Liability \| Changes in Fair Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Increase in estimated fair value	3,600,000
Embedded Put Option \| Changes in Fair Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Increase in estimated fair value	0
Preferred Stock Warrant Liability \| Changes in Fair Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Increase in estimated fair value			1,694,484	60,000
Conversion Feature And Put Option \| Changes in Fair Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Increase in estimated fair value				610,000
Convertible Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of financial instruments	41,400,000		17,350,000	$ 3,650,000
Term Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of financial instruments	$ 13,500,000		$ 9,032,000

Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Balances for Derivative and Warrant Liability Measured at Fair Value on Recurring Basis (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Balance at beginning of period	$ 15,965,891	$ 2,813,260	$ 2,813,260	$ 2,390,608
Issuance of Deerfield Warrant		7,610,000
Embedded Deerfield Put Option		220,000	220,000
Conversion of 2013 Convertible Notes		(1,900,000)	(1,900,000)
Reclassification of 2013 Warrants to equity	(1,110,000)
Exercise of warrants	(271,000)
Adjustment to fair value	26,512,000	4,002,000	7,222,631	(1,137,348)
Balance at end of period	$ 41,097,000	$ 12,744,000	15,965,891	2,813,260
Unsecured Convertible Promissory Notes
Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Issuance of Deerfield Warrant				1,150,000
Deerfield Convertible Notes And Term Notes
Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Issuance of Deerfield Warrant			$ 7,610,000
2013 Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Issuance of Deerfield Warrant				$ 410,000

Income Tax - Additional information (Detail) - USD ($)	9 Months Ended		12 Months Ended
Income Tax - Additional information (Detail) - USD ($)	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Income tax (expense) benefit	$ (27,000)	$ 49,000	$ 22,247	$ 19,544
Loss before income taxes	$ (45,434,000)	$ (12,664,000)	(24,477,008)	$ (5,245,989)
Net operating loss carry forwards			38,368,144
IOWA
Income Tax [Line Items]
Net operating loss carry forwards			$ 38,289,880
Net operating loss carry forwards expiration year, beginning year			2027
Net operating loss carry forwards expiration year, ending year			2034

Income Taxes - Schedule of Reconciliation of Difference Between Benefit for Income Taxes and Income Taxes at Statutory U.S Federal Income Tax Rate (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Effective Income Tax Rate [Line Items]
Federal statutory rate			$ (8,322,268)	$ (1,783,637)
Change in valuation allowance			8,047,512	2,013,636
State income taxes			(1,459,773)	(394,912)
Conversion Feature and Put Option on 2013 Convertible Notes			307,864	462,400
Interest expense			(51,676)	51,676
Other			(16,038)	102,216
Federal income tax provision effective rate	$ 27,000	$ (49,000)	$ (22,247)	$ (19,544)
Federal statutory rate			34.00%	34.00%
Change in valuation allowance			(32.90%)	(38.40%)
State income taxes			6.00%	7.50%
Conversion Feature and Put Option on 2013 Convertible Notes			(1.30%)	(8.80%)
Interest expense			0.20%	(1.00%)
Other			0.10%	(1.90%)
Federal income tax provision effective rate			0.10%	0.40%
Scenario, Adjustment [Member]
Reconciliation Of Effective Income Tax Rate [Line Items]
Federal income tax provision effective rate			$ (22,497)	$ (19,544)
Underwriter Warrant Liability
Reconciliation Of Effective Income Tax Rate [Line Items]
Warrant liability			$ 575,495	$ (454,698)
Warrant liability			(2.40%)	8.70%
Preferred Stock Warrant Liability
Reconciliation Of Effective Income Tax Rate [Line Items]
Warrant liability			$ 1,723,800	$ 136,000
Warrant liability			(7.00%)	(2.60%)
State
Reconciliation Of Effective Income Tax Rate [Line Items]
Research and development credit			$ (22,497)	$ (19,544)
Research and development credit			0.10%	0.40%
Federal
Reconciliation Of Effective Income Tax Rate [Line Items]
Research and development credit			$ (804,916)	$ (132,681)
Research and development credit			3.30%	2.50%

Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets relating to:
Net operating loss carryforwards	$ 16,389,697	$ 9,606,253
Research and development tax carryforward	1,792,778	898,813
Compensation	83,377	75,872
Total gross deferred tax assets	18,265,852	10,580,938
Deferred tax liabilities relating to:
Property and equipment	169,469	175,891
Total gross deferred tax liabilities	169,469	175,891
Deferred tax assets less liabilities	18,096,383	10,405,047
Valuation allowance	(18,096,383)	(10,405,047)
Net deferred tax asset (liability)	$ 0	$ 0

Income Taxes - Federal Net Operating Loss Carryforward And Research Activities Credits (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Net Operating Loss	$ 38,368,144
Research Activities Credit	1,792,778	$ 898,813
Tax Year 2007
Operating Loss Carryforwards [Line Items]
Net Operating Loss	454,280
Research Activities Credit	$ 29,977
Expiration	2027
Tax Year 2008
Operating Loss Carryforwards [Line Items]
Net Operating Loss	$ 1,178,096
Research Activities Credit	$ 64,677
Expiration	2028
Tax Year 2009
Operating Loss Carryforwards [Line Items]
Net Operating Loss	$ 3,060,387
Research Activities Credit	$ 175,635
Expiration	2029
Tax Year 2010
Operating Loss Carryforwards [Line Items]
Net Operating Loss	$ 3,423,056
Research Activities Credit	$ 149,246
Expiration	2030
Tax Year 2011
Operating Loss Carryforwards [Line Items]
Net Operating Loss	$ 9,928,651
Research Activities Credit	$ 176,585
Expiration	2031
Tax Year 2012
Operating Loss Carryforwards [Line Items]
Research Activities Credit	$ 170,012
Expiration	2032
Tax Year 2013
Operating Loss Carryforwards [Line Items]
Net Operating Loss	$ 4,521,783
Research Activities Credit	$ 132,681
Expiration	2033
Tax Year 2014
Operating Loss Carryforwards [Line Items]
Net Operating Loss	$ 15,801,891
Research Activities Credit	$ 893,965
Expiration	2034

Net Loss Per Share - Summary of Computation of Basic and Diluted Net Loss and Net Loss Per Share (Detail) - USD ($)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Dec. 31, 2014

Dec. 31, 2013

Earnings Per Share [Abstract]

$ (45,461,000)

$ (12,615,000)

$ (24,454,761)

^[1]

$ (5,226,445)

Weighted-average number of common shares-basic and diluted

9,643,231

2,381,041

^[2]

2,381,041

Net loss per share-basic and diluted

$ (4.71)

$ (5.30)

$ (10.27)

$ (2.20)

[1]	Represents actual net loss.
[2]	Represents actual weighted average common shares outstanding-basic.

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

Net Loss Per Share - Schedule of Anti-dilutive Securities Excluded from Calculation of Weighted Average Common Shares Outstanding (Detail) - shares	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5,970,076	12,067,666
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,636,180	596,104	595,920	595,920
Deerfield Warrant to Purchase Series D Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		1,923,077	2,066,970	143,893
Warrants to Purchase Series D Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		1,823,827
Equity Incentive Plans
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,390,438	395,200	395,185	296,255
Convertible Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,943,458	1,764,518	1,808,353
Unsecured Convertible Promissory Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount				683,417
Series A Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		1,293,895	1,293,838	1,293,838
Series B Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		829,333	829,234	829,234
Series C Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		2,474,322	2,474,121	2,474,121
Series D Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		967,390	967,359
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		5,564,940

Net Loss Per Share - Calculation of Pro Forma Per Share (Detail) - USD ($)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Dec. 31, 2014

Dec. 31, 2013

Weighted-average number of common shares-basic and diluted

$ (45,461,000)

$ (12,615,000)

$ (24,454,761)

^[1]

$ (5,226,445)

9,643,231

2,381,041

^[2]

2,381,041

Net loss per share-basic and diluted

$ (4.71)

$ (5.30)

$ (10.27)

$ (2.20)

Redeemable Convertible Preferred Stock

Weighted-average number of common shares-basic and diluted

^[3]

5,162,081

Unsecured Convertible Promissory Notes

Weighted-average number of common shares-basic and diluted

^[4]

280,230

Pro Forma

Weighted-average number of common shares-basic and diluted

$ (24,454,761)

7,823,352

Net loss per share-basic and diluted

$ (3.13)

[1]	Represents actual net loss.
[2]	Represents actual weighted average common shares outstanding-basic.
[3]	Represents the number of shares of common stock that would have been outstanding had all outstanding shares of the Preferred Stock converted into shares of common stock as of January 1, 2014 or the issuance dates of the Preferred Stock, if later, computed on a weighted average basis.
[4]	Represents the number of shares of common stock that would have been outstanding had the principal amount and accrued interest of the 2013 Convertible Notes converted into shares of common stock at the beginning of the period or at the time the interest is accrued, computed on a weighted average basis.

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.