Zevra Therapeutics (ZVRA) 10-Q29 May 152015 Q1 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
Document and Entity Information	Mar. 31, 2015	28-May-15
Document Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	KMPH
Entity Registrant Name	KEMPHARM, INC
Entity Central Index Key	1434647
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		14,226,311

CONDENSED_BALANCE_SHEETS

CONDENSED BALANCE SHEETS (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$10,269	$10,255
Prepaid expenses and other current assets	53	23
Total current assets	10,322	10,278
Debt issuance costs, net	1,384	1,468
Property and equipment, net	354	352
Other long-term assets	2,058	1,616
Total assets	14,118	13,714
Current liabilities:
Accounts payable and accrued expenses	4,000	3,903
Current portion of capital lease obligation	32	32
Total current liabilities	4,032	3,935
Convertible notes, net of discount	7,393	7,235
Term notes, net of discount	11,089	10,853
Derivative and warrant liability	17,728	15,966
Capital lease obligation, net of current portion	18	26
Total liabilities	40,260	38,015
Commitments and contingencies (Note D)
Redeemable convertible preferred stock:
Total Redeemable Convertible Preferred Stock	28,210	24,207
Stockholdersâ€™ deficit:
Common stock, $0.0001 par value, 143,200,000 shares authorized, 2,391,202 shares issued and outstanding as of March 31, 2015; $0.0001 par value, 140,000,000 shares authorized, 2,381,041 shares issued and outstanding as of December 31, 2014	2	2
Additional paid-in capital	1,780	1,650
Accumulated deficit	-56,134	-50,160
Total stockholders' deficit	-54,352	-48,508
Total liabilities, redeemable convertible preferred stock, and stockholders' deficit	14,118	13,714
Series A Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock:
Total Redeemable Convertible Preferred Stock	3,343	3,343
Series B Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock:
Total Redeemable Convertible Preferred Stock	3,313	3,313
Series C Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock:
Total Redeemable Convertible Preferred Stock	11,892	11,892
Series D Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock:
Total Redeemable Convertible Preferred Stock	5,662	5,659
Series D-1 Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock:
Total Redeemable Convertible Preferred Stock	$4,000	$0

CONDENSED_BALANCE_SHEETS_PAREN

CONDENSED BALANCE SHEETS (PARENTHETICAL) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Redeemable convertible preferred stock, shares authorized	112,683,000
Redeemable convertible preferred stock, shares issued	3,200,000
Redeemable convertible preferred stock, shares outstanding	44,940,253	41,737,048
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	143,200,000	140,000,000
Common stock, shares issued	2,391,202	2,381,041
Common stock, shares outstanding	2,391,202	2,381,041
Series A Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	9,705,000	9,705,000
Redeemable convertible preferred stock, shares issued	9,704,215	9,704,215
Redeemable convertible preferred stock, shares outstanding	9,704,215	9,704,215
Series B Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	6,220,000	6,220,000
Redeemable convertible preferred stock, shares issued	6,220,000	6,220,000
Redeemable convertible preferred stock, shares outstanding	6,220,000	6,220,000
Series C Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	18,558,000	18,558,000
Redeemable convertible preferred stock, shares issued	18,557,408	18,557,408
Redeemable convertible preferred stock, shares outstanding	18,557,408	18,557,408
Series D Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	75,000,000	75,000,000
Redeemable convertible preferred stock, shares issued	7,258,630	7,255,425
Redeemable convertible preferred stock, shares outstanding	7,258,630	7,255,425
Series D-1 Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	3,200,000	0
Redeemable convertible preferred stock, shares issued	3,200,000	0
Redeemable convertible preferred stock, shares outstanding	3,200,000	0

UNAUDITED_CONDENSED_STATEMENTS

UNAUDITED CONDENSED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenue	$0	$0
Operating expenses:
Research and development	2,119	1,038
General and administrative	977	534
Total operating expenses	3,096	1,572
Loss from operations	-3,096	-1,572
Other expenses:
Amortization of debt discount	-477	0
Interest expense	-632	-96
Fair value adjustment	-1,762	-242
Total other expenses	-2,871	-338
Loss before income taxes	-5,967	-1,910
Income tax (expense) benefit	-7	5
Net loss	($5,974)	($1,905)
Net loss per share:
Basic and diluted	($2.50)	($0.80)
Weighted average common shares outstanding:
Basic and diluted	2,387,092	2,381,041

UNAUDITED_CONDENSED_STATEMENTS1

UNAUDITED CONDENSED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
UNAUDITED CONDENSED STATEMENTS OF CASH FLOWS (USD $)	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	($5,974,000)	($1,905,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	91,000	26,000
Non-cash interest expense	632,000	96,000
Amortization of debt issuance costs and debt discount	477,000	0
Depreciation and amortization expense	20,000	19,000
Fair value adjustment	1,762,000	242,000
Change in assets and liabilities:
Prepaid expenses and other assets	-30,000	46,000
Accounts payable and accrued expenses	-977,000	588,000
Net cash used in operating activities	-3,999,000	-888,000
Cash flows from investing activities:
Purchases of property and equipment	-21,000	-4,000
Net cash used in investing activities	-21,000	-4,000
Cash flows from financing activities:
Repayment of line of credit		-1,000
Payment of stock issuance costs		-13,000
Repayment of obligations under capital lease	-8,000	-8,000
Net cash provided by (used in) financing activities	4,034,000	-22,000
Net increase (decrease) in cash and cash equivalents	14,000	-914,000
Cash and equivalents, beginning of period	10,255,000	1,969,000
Cash and equivalents, end of period	10,269,000	1,055,000
Supplemental cash flow information:
Cash paid for interest		1,000
Non-cash investing and financing activities:
Deferred offering costs included in accounts payable and accrued expenses	442,000
Series D-1 Preferred
Cash flows from financing activities:
Proceeds from issuance of Series D-1 Preferred Stock	4,000,000
Series D Preferred
Cash flows from financing activities:
Proceeds from exercise of warrants	2,000
Common Stock Warrants
Cash flows from financing activities:
Proceeds from exercise of warrants	$40,000

Description_of_Business_and_Ba

Description of Business and Basis of Presentation	3 Months Ended
Description of Business and Basis of Presentation	Mar. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [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 Company has financed its operations primarily through issuances of redeemable convertible preferred stock, and term and convertible notes. With the cash received under the Deerfield Facility Agreement (Note C), the Company believes it has adequate cash on hand to meet its obligations for at least the next twelve months. If required, there can be no assurances that the Company would be successful in obtaining additional financing.
	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 three months ended March 31, 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 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 approximately $58.1 million, after deducting underwriting discounts and commissions of $4.5 million and offering expenses totaling approximately $1.8 million. Upon completion of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock were converted 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. Following the IPO, there were no shares of redeemable convertible preferred stock outstanding. 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. The condensed financial statements, including share and per share amounts, do not give effect to the IPO.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2015
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 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.
	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 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, 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 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 Topic 275 also apply to entities that have not commenced planned principal operations.
	The Company has elected to early adopt ASU 2014-10. 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 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 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.

Debt_Obligations

Debt Obligations	3 Months Ended
	Mar. 31, 2015
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. 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 “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) at any time after an IPO, the shares of 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. 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.
	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 for the Company’s product candidate, KP201/APAP, which consists of KP201, the Company’s new molecular entity prodrug of hydrocodone, formulated in combination with acetaminophen (“APAP”), and, for the final two tranches, the subsequent approval for commercial sale thereof.
	As of March 31, 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 9,615,385 shares of Series D Preferred at an exercise price of $0.78.
	·	The third and fourth tranches each consist of a $12.5 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 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.
	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 initial public offering, as defined in the Deerfield Facility Agreement, has occurred. Upon the closing of the IPO, the Deerfield Convertible Notes became convertible only into shares of the Company’s common stock. Similarly, the Deerfield Warrant became exercisable only for shares of the Company’s common stock upon the closing of the IPO.
	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 accrue interest from the date of issuance through the maturity date, 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. 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.

	Line of Credit
	The Company has a $50,000 credit agreement with a financial institution (the “Line of Credit Agreement”). As of March 31, 2015 and December 31, 2014, the Company had $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 three months ended March 31, 2015, and the year ended December 31, 2014.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2015
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 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 IPO and any future capital raising transactions.

Redeemable_Convertible_Preferr

Redeemable Convertible Preferred Stock and Warrants

3 Months Ended

Mar. 31, 2015

Temporary Equity Disclosure [Abstract]

Redeemable Convertible Preferred Stock and Warrants

E. Redeemable Convertible Preferred Stock and Warrants

Authorized, Issued, and Outstanding Redeemable Convertible Preferred Stock

During February 2015, the Company amended and restated its Certificate of Incorporation to increase the number of its authorized shares of preferred stock to 112,683,000 shares with a par value of $0.0001 per share and to designate 3,200,000 shares as Series D-1 redeemable convertible preferred stock (“Series D-1 Preferred”) in addition to its previously designated and authorized preferred stock.

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”), Series D Preferred, and Series D-1 Preferred as of March 31, 2015:

Authorized

Outstanding

Issue Price

Liquidation

Preference

Series A Preferred

9,705,000

9,704,215

0.4

3,881,686

Series B Preferred

6,220,000

0.62

3,856,400

Series C Preferred

18,558,000

18,557,408

0.78

14,474,778

Series D Preferred

75,000,000

7,258,630

0.78

5,661,731

Series D-1 Preferred

3,200,000

1.25

4,000,000

Total

112,683,000

44,940,253

3,74,596

Preferred Stock Activity

The following table summarizes redeemable convertible preferred stock activity for the three months ended March 31, 2015:

Shares of

Series A

Series B

Series C

Series D

Series D-1

Total

Preferred

Balance, December 31, 2014

9,704,215

6,220,000

18,557,408

7,255,425

—

41,737,048

Shares issued for Cowen Investment

—

3,200,000

Exercise of Series D Preferred warrants

—

3,205

—

3,205

Balance, March 31, 2015

9,704,215

6,220,000

18,557,408

7,258,630

3,200,000

44,940,253

Series D-1 Redeemable Convertible Preferred Stock

In February 2015, the Company entered into a stock purchase agreement with Cowen KP Investment LLC (“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.

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, Series D Preferred, Series D-1 Preferred (the Series D Preferred and the Series D-1 Preferred, together, the “Senior Preferred Stock”) 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 and issue price is as follows with respect to any share of:

Series A Preferred, $0.40 per share;

Series B Preferred, $0.62 per share;

Series C Preferred, $0.78 per share;

Series D Preferred, $0.78 per share; and

Series D-1 Preferred, $1.25 per share;

However, if the Company effected an initial public offering, then the Series D-1 Preferred had a conversion price per share equal to the greater of the conversion price described above, as adjusted for any event described below, or 87.5% of the initial public offering price per share.

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, Series D Preferred and/or Series D-1 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 Company’s board of directors (the “Board”); 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 million of gross proceeds to the Company and a listing of the common stock on the NASDAQ Stock Market or the New York Stock Exchange. The Company’s IPO was a Qualified Public Offering, and, consequently, all shares of Preferred Stock converted into shares of the Company’s common stock on April 21, 2015.

Dividend Rights

With respect to the Company’s payment of dividends or distributions, if any, the Senior Preferred Stock 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 and are noncumulative.

Voting Rights

The Company’s Series A Preferred, Series B Preferred, Series C Preferred, and Series D-1 Preferred are non-voting except to the extent voting rights are required by General Corporation Law of the State of Delaware. Each holder of Senior Preferred Stock is entitled to cast the number of votes equal to the number of whole shares of common stock into which the shares of Senior Preferred Stock held by such holder are convertible. Holders of Senior Preferred Stock 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 the Senior Preferred Stock 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 the Senior Preferred Stock 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 Senior Preferred Stock 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 Senior Preferred Stock, 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.

Senior Preferred Stock 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 Senior Preferred Stock, 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 Amended and Restated Certificate of Incorporation or Bylaws in a manner that adversely affects the holders of Senior Preferred Stock;

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

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

issue any shares of Senior Preferred Stock 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 Senior Preferred Stock 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 Senior Preferred Stock with respect to any such right, preference, or privilege or (ii) that is junior to the Senior Preferred Stock 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 Senior Preferred Stock 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 Senior Preferred Stock with respect to the payment of dividends or distributions, or to any holders of shares of a class of capital stock issued following the Senior Preferred Stock original issue date that is pari passu to the Senior Preferred Stock 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 Senior Preferred Stock original issue date that is pari passu to the Senior Preferred Stock; provided, however, that the approval by the Senior Preferred Stock 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 Board approval, (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 Senior Preferred Stock as expressly authorized in the Certificate of Incorporation; or

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

Warrants

As of March 31, 2015, outstanding warrants to purchase the Company’s Series D Preferred were as follows:

Issuance Date

Number of

Exercise

Underlying

Price

2013

1,076,248

0.78

2014

14,423,076

0.78

15,499,324

The following table summarized the Company’s Series D Preferred warrant activity for the three months ended March 31, 2015:

Number of

Underlying

Beginning balance at December 31, 2014

15,502,529

Less: Series D Preferred warrants exercised

3,205

Ending balance at March 31, 2015

15,499,324

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. 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. 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 H).

Common_Stock_and_Warrants

Common Stock and Warrants	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Common Stock and Warrants	F. Common Stock and Warrants
	Authorized, Issued, and Outstanding Common Shares
	In February 2015, the Company amended and restated its Certificate of Incorporation to increase the number of its authorized shares of common stock to 143,200,000 shares. Of the authorized shares, 2,391,202 and 2,381,041 shares of common stock were issued and outstanding at March 31, 2015, and December 31, 2014, respectively.

	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.

	Dividend and Voting Rights
	The holders of the common stock are entitled to receive dividends, when and if declared by the Board 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.
	At March 31, 2015, 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		2,474,122
	Conversion of Series D Preferred		967,786
	Conversion of Series D-1 Preferred		426,667
	Conversion of Deerfield Convertible Notes		1,851,828
	Outstanding awards under Incentive Stock Plan		549,824
	Outstanding common stock warrants		585,759
	Outstanding Series D Preferred warrants		2,066,543
	Possible future issuances under Incentive Stock Plan		211,067
	Total common shares reserved for future issuance		11,256,668

	Common Stock Activity
	The following table summarizes common stock activity for the three months ended March 31, 2015:

		Shares of
		Common Stock
	Beginning balance at December 31, 2014		2,381,041
	Common stock warrants exercised		10,161
	Ending balance at March 31, 2015		2,391,202
	The Company calculates the fair value of common stock warrants using a Monte Carlo simulation. There were warrants exercised for an aggregate of 10,161 shares of common stock during the three months ended March 31, 2015, and there were no warrants exercised in the three months ended March 31, 2014. From 2008 through 2012, the Company issued warrants to purchase 595,220 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 Statement of Operations.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	G. 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. In July 2014, the Company’s Incentive Stock Plan was revised to increase the maximum number of shares issuable under the Plan from 5,000,000 to 6,000,000. No stock options were exercised during the three months ended March 31, 2015 or 2014, respectively.

	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, at which time the Incentive Stock Plan was terminated. 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.
	Stock-based compensation expense recorded under the Plan is included in the following line items in the accompanying statements of operations (in thousands):

		Three Months Ended March 31,
		2015		2014
	Research and development	$	41	$	6
	General and administrative		50		20
		$	91	$	26

	During the three months ended March 31, 2015, the Company recognized approximately $29,000 of stock-based compensation expense related to performance-based awards included in general and administrative expenses in connection with the grant of fully vested stock options exercisable for an aggregate of 5,333 shares of common stock as a result of the Company issuing shares of Series D-1 Preferred. The Company did not recognize any stock-based compensation expense related to performance-based incentive awards during the three months ended March 31 2014, as the strategic initiatives set forth in the grants were not achieved or probable of achievement.

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	3 Months Ended
Fair Value of Financial Instruments	Mar. 31, 2015
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 $18.8 million and $11.8 million, respectively, at March 31, 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 judgments to be made. The following table summarizes the conclusions reached regarding fair value measurements as of March 31, 2015, and December 31, 2014 (in thousands):

		Balance at		Quoted Prices		Significant		Significant
		March 31,		in Active		Other		Unobservable
		2015		Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Underwriter Warrant liability	$	3,078	$	—	$	—	$	3,078
	Preferred stock warrant liability		14,580		—		—		14,580
	Embedded Deerfield Put Option		70		—		—		70
		$	17,728	$	—	$	—	$	17,728

		Balance at		Quoted Prices		Significant		Significant
		31-Dec-14		in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Underwriter Warrant liability	$	2,746	$	—	$	—	$	2,746
	Preferred stock warrant liability		13,080		—		—		13,080
	Embedded Deerfield Put Option		140		—		—		140
		$	15,966	$	—	$	—	$	15,966

	The Company’s Underwriter Warrant liability, preferred stock warrant liability, and the embedded Deerfield Put Option on the Deerfield Warrant are measured at fair value on a recurring basis. As of March 31, 2015 and 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, the preferred stock warrant liability, and the embedded Deerfield Put Option at March 31, 2015 and December 31, 2014. 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, 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 embedded Deerfield 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 approximately $469,000 in the estimated fair value of the Underwriter Warrant liability, an increase of approximately $1.8 million 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 March 31, 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):

		Three Months Ended March 31,
		2015		2014
	Balance at beginning of period	$	15,966	$	2,813
	Adjustment to fair value		1,762		242
	Balance at end of period	$	17,728	$	3,055

Net_Loss_Per_Share

Net Loss Per Share	3 Months Ended
Net Loss Per Share	Mar. 31, 2015
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 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 three month periods ended March 31, 2015 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 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:

		Three Months Ended March 31,
		2015		2014
	Redeemable convertible preferred stock:
	Series A		1,293,838		1,293,838
	Series B		829,234		829,234
	Series C		2,474,122		2,474,122
	Series D		967,786		—
	Series D-1		426,667		—
	Total redeemable convertible preferred stock		5,991,647		4,597,194
	Warrants to purchase common stock		585,759		595,920
	Warrants to purchase Series D Preferred		2,066,543		143,893
	Awards under Incentive Stock Plan		549,824		297,587
	2013 Convertible Notes		—		699,628
	Deerfield Convertible Notes		1,851,828		—
	Total		11,045,601		6,334,222

Subsequent_Events

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	J. Subsequent Events

	Reverse Stock Split
	In April 2015, the Company amended its Amended and Restated Certificate of Incorporation effecting a 1-for-7.5 reverse stock split of its common stock, as described in Note A.

	Initial Public Offering
	In April 2015, the Company completed its IPO of 5,090,909 shares of common stock followed by a subsequent sale of 763,636 shares of common stock to the underwriters in the IPO pursuant to their option to purchase additional shares, as described in Note A.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2015
Accounting Policies [Abstract]
Use of Estimates	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 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.
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.
	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 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, 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 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 Topic 275 also apply to entities that have not commenced planned principal operations.
	The Company has elected to early adopt ASU 2014-10. 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	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 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 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.

Redeemable_Convertible_Preferr1

Redeemable Convertible Preferred Stock and Warrants (Tables)	3 Months Ended
	Mar. 31, 2015
Temporary Equity Disclosure [Abstract]
Summary of Authorized, Issued and Outstanding Redeemable Convertible Preferred Stock	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”), Series D Preferred, and Series D-1 Preferred as of March 31, 2015:

		Authorized		Outstanding		Issue Price		Liquidation
		Authorized		Outstanding		Issue Price		Preference
	Series A Preferred		9,705,000		9,704,215	$	0.4	$	3,881,686
	Series B Preferred		6,220,000		6,220,000	$	0.62		3,856,400
	Series C Preferred		18,558,000		18,557,408	$	0.78		14,474,778
	Series D Preferred		75,000,000		7,258,630	$	0.78		5,661,731
	Series D-1 Preferred		3,200,000		3,200,000	$	1.25		4,000,000
	Total		112,683,000		44,940,253			$	3,74,596

Summary of Redeemable Convertible Preferred Stock Activity	The following table summarizes redeemable convertible preferred stock activity for the three months ended March 31, 2015:

		Shares of
		Series A		Series B		Series C		Series D		Series D-1		Total
		Preferred		Preferred		Preferred		Preferred		Preferred		Total
	Balance, December 31, 2014		9,704,215		6,220,000		18,557,408		7,255,425		—		41,737,048
	Shares issued for Cowen Investment		—		—		—		—		3,200,000		3,200,000
	Exercise of Series D Preferred warrants		—		—		—		3,205		—		3,205
	Balance, March 31, 2015		9,704,215		6,220,000		18,557,408		7,258,630		3,200,000		44,940,253

Schedule of Outstanding Warrants to Purchase the Company's Series D Preferred	As of March 31, 2015, outstanding warrants to purchase the Company’s Series D Preferred were as follows:

	Issuance Date	Number of		Exercise
		Underlying		Price
		Shares
	2013		1,076,248	$	0.78
	2014		14,423,076	$	0.78
			15,499,324


	The following table summarized the Company’s Series D Preferred warrant activity for the three months ended March 31, 2015:

		Number of
		Underlying
		Shares
	Beginning balance at December 31, 2014	15,502,529
	Less: Series D Preferred warrants exercised	3,205
	Ending balance at March 31, 2015	15,499,324

Common_Stock_and_Warrants_Tabl

Common Stock and Warrants (Tables)	3 Months Ended
Common Stock and Warrants (Tables)	Mar. 31, 2015
Equity [Abstract]
Schedule of Authorized Shares of Common Stock Reserved for Future Issuance	At March 31, 2015, 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		2,474,122
	Conversion of Series D Preferred		967,786
	Conversion of Series D-1 Preferred		426,667
	Conversion of Deerfield Convertible Notes		1,851,828
	Outstanding awards under Incentive Stock Plan		549,824
	Outstanding common stock warrants		585,759
	Outstanding Series D Preferred warrants		2,066,543
	Possible future issuances under Incentive Stock Plan		211,067
	Total common shares reserved for future issuance		11,256,668

Schedule of Common Stock Shares Activity	The following table summarizes common stock activity for the three months ended March 31, 2015:

		Shares of
		Common Stock
	Beginning balance at December 31, 2014		2,381,041
	Common stock warrants exercised		10,161
	Ending balance at March 31, 2015		2,391,202

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
Stock-Based Compensation (Tables)	Mar. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Stock-Based Compensation Expense	Stock-based compensation expense recorded under the Plan is included in the following line items in the accompanying statements of operations (in thousands):

		Three Months Ended March 31,
		2015		2014
	Research and development	$	41	$	6
	General and administrative		50		20
		$	91	$	26

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	3 Months Ended
Fair Value of Financial Instruments (Tables)	Mar. 31, 2015
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 March 31, 2015, and December 31, 2014 (in thousands):

		Balance at		Quoted Prices		Significant		Significant
		March 31,		in Active		Other		Unobservable
		2015		Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Underwriter Warrant liability	$	3,078	$	—	$	—	$	3,078
	Preferred stock warrant liability		14,580		—		—		14,580
	Embedded Deerfield Put Option		70		—		—		70
		$	17,728	$	—	$	—	$	17,728

		Balance at		Quoted Prices		Significant		Significant
		31-Dec-14		in Active		Other		Unobservable
				Markets for		Observable		Inputs
				Identical		Inputs		(Level 3)
				Assets		(Level 2)
				(Level 1)
	Underwriter Warrant liability	$	2,746	$	—	$	—	$	2,746
	Preferred stock warrant liability		13,080		—		—		13,080
	Embedded Deerfield Put Option		140		—		—		140
		$	15,966	$	—	$	—	$	15,966

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

		Three Months Ended March 31,
		2015		2014
	Balance at beginning of period	$	15,966	$	2,813
	Adjustment to fair value		1,762		242
	Balance at end of period	$	17,728	$	3,055

Net_Loss_Per_Share_Tables

Net Loss Per Share (Tables)	3 Months Ended
Net Loss Per Share (Tables)	Mar. 31, 2015
Earnings Per Share [Abstract]
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:

		Three Months Ended March 31,
		2015		2014
	Redeemable convertible preferred stock:
	Series A		1,293,838		1,293,838
	Series B		829,234		829,234
	Series C		2,474,122		2,474,122
	Series D		967,786		—
	Series D-1		426,667		—
	Total redeemable convertible preferred stock		5,991,647		4,597,194
	Warrants to purchase common stock		585,759		595,920
	Warrants to purchase Series D Preferred		2,066,543		143,893
	Awards under Incentive Stock Plan		549,824		297,587
	2013 Convertible Notes		—		699,628
	Deerfield Convertible Notes		1,851,828		—
	Total		11,045,601		6,334,222

Description_of_Business_and_Ba1

Description of Business and Basis of Presentation - Additional Information (Details) (USD $)	3 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	31-May-15	Apr. 30, 2015	Feb. 28, 2015	Dec. 31, 2014
Class Of Stock [Line Items]
Reverse stock split, description	1-for-7.5 reverse stock split
Redeemable convertible preferred stock, shares outstanding	44,940,253				41,737,048
Common stock, shares authorized	143,200,000			143,200,000	140,000,000
Common stock, par value	$0.00				$0.00
IPO \| Forecast
Class Of Stock [Line Items]
Common stock, price per share		$11
Additional number of common stock sold		763,636
Net proceeds from initial public offering (IPO)		$58.10
Underwriting discounts and commissions		4.5
IPO offering expenses		$1.80
Number of preferred shares converted to common shares		5,980,564
Redeemable convertible preferred stock, shares outstanding		0
Common stock, shares authorized		250,000,000
Preferred stock designated as common stock		10,000,000
Common stock, par value		$0.00
Preferred stock, par value		$0.00
Subsequent Event
Class Of Stock [Line Items]
Reverse stock split			0.13
Subsequent Event \| IPO
Class Of Stock [Line Items]
Number of shares of common stock sold			5,090,909
Common stock, price per share			11
Additional number of common stock sold			763,636

Debt_Obligations_Additional_In

Debt Obligations - Additional Information (Details) (USD $)	3 Months Ended	0 Months Ended	5 Months Ended
Debt Obligations - Additional Information (Details) (USD $)	Mar. 31, 2015	Jun. 02, 2014	Oct. 31, 2013	Dec. 31, 2014
Debt Instrument [Line Items]
Line of credit	50,000			$50,000
Line of Credit Agreement
Debt Instrument [Line Items]
Convertible notes, interest rate	5.00%			5.00%
Line of credit, description of variable rate basis	prime rate plus 1.75% per annum
Line of credit, basis spread on variable rate	1.75%
Series D Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Preferred stock called by warrants	1,079,453
Deerfield Warrant
Debt Instrument [Line Items]
Warrants expiration date		2-Jun-24
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.
Facility agreement, repayment period	14-Feb-20
Line of Credit Interest Payment, Due Date	1-Jul-16
Line of credit agreement, available borrowing capacity	35,000,000
Deerfield Facility Agreement \| First Tranche
Debt Instrument [Line Items]
Percentage of outstanding principal amount to be repaid	33.33%
Deerfield Facility Agreement \| Second Tranche
Debt Instrument [Line Items]
Facility agreement, interest rate	9.75%
Line of credit agreement, available borrowing capacity	10,000,000
Deerfield Facility Agreement \| Third Tranche
Debt Instrument [Line Items]
Facility agreement, interest rate	9.75%
Line of credit agreement, available borrowing capacity	12,500,000
Warrants exercisable as percentage of principal amount of debt disbursed	60.00%
Consecutive trading days, threshold for warrant exercise	20 days
Deerfield Facility Agreement \| Fourth Tranche
Debt Instrument [Line Items]
Facility agreement, interest rate	9.75%
Line of credit agreement, available borrowing capacity	12,500,000
Warrants exercisable as percentage of principal amount of debt disbursed	60.00%
Consecutive trading days, threshold for warrant exercise	20 days
Deerfield Facility Agreement \| Put Option
Debt Instrument [Line Items]
Fair value of embedded put option		220,000
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 \| Deerfield Warrant
Debt Instrument [Line Items]
Warrant, exercise price		0.78
Warrants expiration date		2-Jun-24
Fair value of warrants		7,600,000
Term Notes \| Deerfield Facility Agreement
Debt Instrument [Line Items]
Facility agreement		15,000,000
Deerfield Convertible Notes \| Deerfield Facility Agreement
Debt Instrument [Line Items]
Facility agreement		10,000,000
Convertible notes, conversion description	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 initial public offering, as defined in the Deerfield Facility Agreement, has occurred.
Deerfield Convertible Notes \| Deerfield Facility Agreement \| Series D Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion price	0.78
Unsecured Convertible Promissory Notes
Debt Instrument [Line Items]
Convertible notes, interest rate			10.00%
Gross proceeds from issuance of convertible notes			3,800,000
Outstanding principal balance of convertible notes		3,800,000
Accrued Interest		300,000
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

Redeemable_Convertible_Preferr2

Redeemable Convertible Preferred Stock and Warrants - Authorized, Issued, and Outstanding Redeemable Convertible Preferred Stock - Additional Information (Details) (USD $)	Mar. 31, 2015	Feb. 28, 2015	Dec. 31, 2014
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	112,683,000	112,683,000
Redeemable convertible preferred stock, par value		0.0001
Series D-1 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	3,200,000	3,200,000	0
Redeemable convertible preferred stock, par value	$0.00		$0.00

Redeemable_Convertible_Preferr3

Redeemable Convertible Preferred Stock and Warrants - Summary of Authorized, Issued, and Outstanding Redeemable Convertible Preferred Stock (Details) (USD $)	Mar. 31, 2015	Feb. 28, 2015	Dec. 31, 2014
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	112,683,000	112,683,000
Redeemable convertible preferred stock, shares outstanding	44,940,253		41,737,048
Redeemable convertible preferred stock, liquidation preference	$374,596
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	9,705,000		9,705,000
Redeemable convertible preferred stock, shares outstanding	9,704,215		9,704,215
Redeemable convertible preferred stock, issue price	$0.40
Redeemable convertible preferred stock, liquidation preference	3,881,686
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	6,220,000		6,220,000
Redeemable convertible preferred stock, shares outstanding	6,220,000		6,220,000
Redeemable convertible preferred stock, issue price	$0.62
Redeemable convertible preferred stock, liquidation preference	3,856,400
Series C Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	18,558,000		18,558,000
Redeemable convertible preferred stock, shares outstanding	18,557,408		18,557,408
Redeemable convertible preferred stock, issue price	$0.78
Redeemable convertible preferred stock, liquidation preference	14,474,778
Series D Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	75,000,000		75,000,000
Redeemable convertible preferred stock, shares outstanding	7,258,630		7,255,425
Redeemable convertible preferred stock, issue price	$0.78
Redeemable convertible preferred stock, liquidation preference	5,661,731
Series D-1 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	3,200,000	3,200,000	0
Redeemable convertible preferred stock, shares outstanding	3,200,000		0
Redeemable convertible preferred stock, issue price	$1.25
Redeemable convertible preferred stock, liquidation preference	$4,000,000

Redeemable_Convertible_Preferr4

Redeemable Convertible Preferred Stock and Warrants - Summary of Redeemable Convertible Preferred Stock Activity (Details)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance	41,737,048
Redeemable convertible preferred stock, shares issued for Cowen Investment	3,200,000
Redeemable convertible preferred stock, exercise of Series D Preferred warrants	3,205
Redeemable convertible preferred stock, shares outstanding, ending balance	44,940,253
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		9,704,215
Redeemable convertible preferred stock, shares issued for Cowen Investment	9,704,215	9,704,215
Redeemable convertible preferred stock, shares outstanding, ending balance	9,704,215	9,704,215
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		6,220,000
Redeemable convertible preferred stock, shares issued for Cowen Investment	6,220,000	6,220,000
Redeemable convertible preferred stock, shares outstanding, ending balance	6,220,000	6,220,000
Series C Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		18,557,408
Redeemable convertible preferred stock, shares issued for Cowen Investment	18,557,408	18,557,408
Redeemable convertible preferred stock, shares outstanding, ending balance	18,557,408	18,557,408
Series D Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance	7,255,425
Redeemable convertible preferred stock, shares issued for Cowen Investment	7,258,630	7,255,425
Redeemable convertible preferred stock, exercise of Series D Preferred warrants	3,205
Redeemable convertible preferred stock, shares outstanding, ending balance	7,258,630
Series D-1 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares outstanding, beginning balance		0
Redeemable convertible preferred stock, shares issued for Cowen Investment	3,200,000	0
Redeemable convertible preferred stock, shares outstanding, ending balance	3,200,000	0

Redeemable_Convertible_Preferr5

Redeemable Convertible Preferred Stock and Warrants - Series D-1 Redeemable Convertible Preferred Stock - Additional Information (Details) (Cowen KP Investment LLC, Series D-1 Redeemable Convertible Preferred Stock, USD $)	1 Months Ended
In Millions, except Share data, unless otherwise specified	Feb. 28, 2015
Cowen KP Investment LLC \| Series D-1 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Number of shares sold under purchase agreement with Cowen KP Investment	3,200,000
Sale of shares, price per share	$1.25
Sale of stock, consideration received	$4

Redeemable_Convertible_Preferr6

Redeemable Convertible Preferred Stock and Warrants - Conversion Rights - Additional Information (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015
IPO
Temporary Equity [Line Items]
Sale of common stock, price per share	$9.38
Minimum \| IPO
Temporary Equity [Line Items]
Proceeds from issuance of common stock	$25
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, issue price	$0.40
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, issue price	$0.62
Series C Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, issue price	$0.78
Series D Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, issue price	$0.78
Series D-1 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, issue price	$1.25
Percentage of initial public offering	87.50%

Redeemable_Convertible_Preferr7

Redeemable Convertible Preferred Stock and Warrants - Senior Preferred Stock Protective Provisions - Additional Information (Details) (USD $)	Mar. 31, 2015
Temporary Equity Disclosure [Abstract]
Repurchase of additional shares	$100,000

Redeemable_Convertible_Preferr8

Redeemable Convertible Preferred Stock and Warrants - Series D Preferred Protective Provisions - Outstanding Warrants to Purchase the Company's Series D Preferred (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Class Of Warrant Or Right [Line Items]
Number of warrants	15,499,324	15,502,529
Less: Series D Preferred warrants exercised	3,205
Year 1
Class Of Warrant Or Right [Line Items]
Issuance Date	2013
Number of warrants	1,076,248
Warrant, exercise price	0.78
Year 2
Class Of Warrant Or Right [Line Items]
Issuance Date	2014
Number of warrants	14,423,076
Warrant, exercise price	0.78

Redeemable_Convertible_Preferr9

Redeemable Convertible Preferred Stock and Warrants - Warrants on Equity Securities - Additional Information (Details) (USD $)	3 Months Ended	12 Months Ended	0 Months Ended
	Mar. 31, 2015	Dec. 31, 2013	Jun. 02, 2014
Convertible Notes
Temporary Equity [Line Items]
Debt instrument issued		3,800,000
Series D Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Preferred stock called by warrants	1,079,453
2013 Warrants
Temporary Equity [Line Items]
Warrants issued		1,079,453
Warrants expiration date	2-Jun-19
Deerfield Warrant
Temporary Equity [Line Items]
Warrants issued			14,423,076
Warrants expiration date			2-Jun-24

Common_Stock_and_Warrants_Addi

Common Stock and Warrants - Additional Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 28, 2015	Dec. 31, 2014	Dec. 31, 2012
Class Of Stock [Line Items]
Common stock, par value			$0
Common stock, shares authorized	143,200,000		143,200,000	140,000,000
Common stock, shares issued	2,391,202			2,381,041
Common stock, shares outstanding	2,391,202			2,381,041
Common stock warrants exercised	10,161	0
Private Placement
Class Of Stock [Line Items]
Preferred stock called by warrants					595,220

Common_Stock_and_Warrants_Sche

Common Stock and Warrants - Schedule of Reserved Authorized Shares of Common Stock for Future Issuance (Details)	Mar. 31, 2015
Class Of Stock [Line Items]
Common shares reserved for future issuance	11,256,668
Series A Preferred
Class Of Stock [Line Items]
Common shares reserved for future issuance	1,293,838
Series B Preferred
Class Of Stock [Line Items]
Common shares reserved for future issuance	829,234
Series C Preferred
Class Of Stock [Line Items]
Common shares reserved for future issuance	2,474,122
Series D Preferred
Class Of Stock [Line Items]
Common shares reserved for future issuance	967,786
Series D-1 Preferred
Class Of Stock [Line Items]
Common shares reserved for future issuance	426,667
Convertible Notes
Class Of Stock [Line Items]
Common shares reserved for future issuance	1,851,828
Series D Preferred Warrants
Class Of Stock [Line Items]
Common shares reserved for future issuance	2,066,543
Incentive Stock Plan
Class Of Stock [Line Items]
Common shares reserved for future issuance	549,824
Possible Future Issuances Under Incentive Stock Plan
Class Of Stock [Line Items]
Common shares reserved for future issuance	211,067
Common Stock Warrants
Class Of Stock [Line Items]
Common shares reserved for future issuance	585,759

Common_Stock_and_Warrants_Summ

Common Stock and Warrants - Summary of Common Stock Shares Activity (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Common Stock Number Of Shares Par Value And Other Disclosures [Abstract]
Common stock, beginning balance	2,381,041
Common stock warrants exercised	10,161	0
Common stock, ending balance	2,391,202

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Jul. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issuable		5,000,000		6,000,000
Stock options exercised	0	0
Stock based compensation expense	$91,000	$26,000
Stock options granted	5,333
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	50,000	20,000
2014 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issuable	2,266,666
Percentage of outstanding capital stock			4.00%
Performance-Based Incentive Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense		0
Performance-Based Incentive Awards \| General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	$29,000

StockBased_Compensation_Schedu

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	$91,000	$26,000
Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	41,000	6,000
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation expense	$50,000	$20,000

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments - Additional Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Increase in estimated fair value	$1,762,000	$242,000
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%
Convertible Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of financial instruments	18,800,000
Term Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of financial instruments	11,800,000
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	469,000
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	1,800,000
Embedded Deerfield 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

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	$17,728	$15,966
Underwriter Warrant Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	3,078	2,746
Preferred Stock Warrant Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	14,580	13,080
Embedded Deerfield Put Option
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	70	140
Significant Unobservable Inputs (Level 3)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	17,728	15,966
Significant Unobservable Inputs (Level 3) \| Underwriter Warrant Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	3,078	2,746
Significant Unobservable Inputs (Level 3) \| Preferred Stock Warrant Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	14,580	13,080
Significant Unobservable Inputs (Level 3) \| Embedded Deerfield Put Option
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Financial assets and liabilities measured at fair value on recurring basis	$70	$140

Fair_Value_of_Financial_Instru4

Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Balances for Derivative and Warrant Liability Measured at Fair Value on Recurring Basis (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value adjustment	$1,762,000	$242,000
Significant Unobservable Inputs (Level 3)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	15,966,000	2,813,000
Fair value adjustment	1,762,000	242,000
Balance at end of period	$17,728,000	$3,055,000

Net_Loss_Per_Share_Schedule_of

Net Loss Per Share - Schedule of Anti-dilutive Securities Excluded from Calculation of Weighted Average Common Shares Outstanding (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	11,045,601	6,334,222
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	1,293,838	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	829,234	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	2,474,122	2,474,122
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	967,786
Series D-1 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	426,667
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	5,991,647	4,597,194
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	585,759	595,920
Warrants to Purchase Series D Preferred
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,066,543	143,893
Incentive Stock Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	549,824	297,587
2013 Convertible Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		699,628
Convertible Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,851,828

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Details)	3 Months Ended	1 Months Ended
Subsequent Events - Additional Information (Details)	Mar. 31, 2015	Apr. 30, 2015
Subsequent Event [Line Items]
Reverse stock split, description	1-for-7.5 reverse stock split
Subsequent Event
Subsequent Event [Line Items]
Reverse stock split		0.13
Subsequent Event \| IPO
Subsequent Event [Line Items]
Number of shares of common stock sold		5,090,909
Additional number of common stock sold		763,636