Rocket Pharmaceuticals (RCKT) 10-Q 14 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	13-May-15
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	ITEK
Entity Registrant Name	Inotek Pharmaceuticals Corporation
Entity Central Index Key	1281895
Current Fiscal Year End Date	-19
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		16,327,003

Balance_Sheets

Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$53,139	$3,618
Prepaid expenses and other current assets	301	52
Total current assets	53,440	3,670
Other assets	2,086	1,850
Total assets	55,526	5,520
Current liabilities:
Notes payable, current portion		3,063
Accounts payable	1,301	1,146
Accrued expenses and other current liabilities	1,052	992
Accrued interest	104
Convertible bridge notes		1,541
Convertible bridge notes redemption rights derivative		480
Total current liabilities	2,457	7,222
2020 Convertible Notes, net of debt discount of $12,333	8,667
Notes payable, net of current portion		2,550
Warrant liabilities		482
2020 Convertible Notes derivative	10,426
Other long-term liabilities	24	24
Total liabilities	21,574	10,278
Redeemable convertible preferred stock		46,801
Commitments and Contingencies (Note 6)
Stockholders' equity (deficit):
Preferred Stock. $0.001 par value: 5,000,000 shares authorized and 0 shares issued or outstanding
Common stock, $0.01 par value; 120,000,000 shares and 43,509,727 shares authorized at March 31, 2015 and December 31, 2014, respectively; 16,327,003 shares and 1,020,088 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	163	10
Additional paid-in capital	163,292	76,472
Accumulated deficit	-129,503	-128,041
Total stockholders' equity (deficit)	33,952	-51,559
Total Liabilities, Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)	55,526	5,520
Series AA Redeemable Convertible Preferred Stock [Member]
Current liabilities:
Redeemable convertible preferred stock		46,253
Series X Redeemable Convertible Preferred Stock [Member]
Current liabilities:
Redeemable convertible preferred stock		$548

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Share data, unless otherwise specified
Convertible notes, debt discount	$12,333	$12,333
Preferred stock, shares authorized		28,659,924
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	120,000,000	43,509,727
Common stock, shares issued	16,327,003	1,020,088
Common stock, shares outstanding	16,327,003	1,020,088
Series AA Redeemable Convertible Preferred Stock [Member]
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	0	25,757,874
Preferred stock, shares issued	0	24,057,013
Preferred stock, shares outstanding	0	24,057,013
Series X Redeemable Convertible Preferred Stock [Member]
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	0	2,902,050
Preferred stock, shares issued	0	1,892,320
Preferred stock, shares outstanding	0	1,892,320

Statements_of_Operations

Statements of Operations (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating expenses:
Research and development	($1,069)	($1,550)
General and administrative	-1,980	-162
Loss from operations	-3,049	-1,712
Interest expense	-474	-243
Loss on extinguishment of debt	-683
Change in fair value of warrant liabilities	267	-193
Change in fair value of convertible bridge notes redemption rights derivative	480
Change in fair value of 2020 Convertible Notes derivative	1,997
Net loss	($1,462)	($2,148)
Net loss per share attributable to common stockholders-basic and diluted	($0.21)	($3.08)
Weighted-average number of shares outstanding-basic and diluted	7,677,575	1,020,088

Statement_of_Cash_Flows

Statement of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	($1,462)	($2,148)
Adjustments to reconcile net loss to cash used in operating activities:
Noncash interest expense	274	51
Loss on extinguishment of debt	522
Change in fair value of warrant liabilities	-267	193
Change in fair value of convertible bridge notes redemption rights derivative	-480
Change in fair value of 2020 Convertible Notes derivative	-1,997
Stock-based compensation	1,364	2
Changes in operating assets and liabilities:
Prepaid expenses and other assets	-271	29
Accounts payable	154	-36
Accrued expenses and other current liabilities	170	54
Net cash used in operating activities	-1,993	-1,855
Cash flows from investing activities:
Net cash provided by investing activities:	0	0
Cash flows from financing activities:
Proceeds from issuance of common stock in initial public offering, net of issuance costs	38,155
Proceeds from issuance of 2020 Convertible Notes in initial public offering	21,000
Payments of 2020 Convertible Notes issuance costs	-1,841
Principal and termination payments on notes payable	-5,800
Net cash provided by financing activities:	51,514
Net change in cash and cash equivalents	49,521	-1,855
Cash and cash equivalents, beginning of period	3,618	12,793
Cash and cash equivalents, end of period	53,139	10,938
Supplemental disclosure of cash flow information:
Cash paid for interest	89	192
IPO [Member]
Supplemental disclosure of noncash investing and financing activities:
Conversion of Convertible Bridge Notes into common stock upon initial public offering	2,028
Reclassification of fair value of warrant liability to equity upon initial public offering	215
Reclassification of deferred public offering costs to stockholders's equity	1,590
Reclassification of deferred public offering costs to other assets	256
Series AA Redeemable Convertible Preferred Stock [Member]
Supplemental disclosure of noncash investing and financing activities:
Accrual of Series AA preferred stock dividends		794
Accretion of Series AA preferred stock to redemption value	130	199
Series AA Redeemable Convertible Preferred Stock [Member] | IPO [Member]
Supplemental disclosure of noncash investing and financing activities:
Conversion of Series AA preferred stock into common stock upon initial public offering	46,383
Series X Redeemable Convertible Preferred Stock [Member] | IPO [Member]
Supplemental disclosure of noncash investing and financing activities:
Conversion of Series AA preferred stock into common stock upon initial public offering	$548

Organization_and_Operations

Organization and Operations	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Organization and Operations	1. Organization and Operations
	Inotek Pharmaceuticals Corporation (the “Company”) is a clinical-stage biopharmaceutical company advancing molecules with novel mechanisms of action to address significant diseases of the eye. The Company’s business strategy is to develop and progress its product candidates through human clinical trials. The Company’s headquarters is located in Lexington, Massachusetts.
	The Company has devoted substantially all of its efforts to research and development, including clinical trials of its product candidates. The Company has not completed the development of any product candidates. The Company has no current source of revenue to sustain present activities and does not expect to generate revenue until and unless the Company receives regulatory approval of and successfully commercializes its product candidates. The Company is subject to a number of risks and uncertainties similar to those of other life science companies developing new products, including, among others, the risks related to the necessity to obtain adequate additional financing, to successfully develop product candidates, to obtain regulatory approval of products candidates, to comply with government regulations, to successfully commercialize its potential products, to the protection of proprietary technology and to the dependence on key individuals.
	In February 2015, the Company completed its initial public offering (the “IPO”) of (i) 6,667,000 shares of common stock at a price of $6.00 per share and (ii) $20,000 aggregate principal amount of 5.0% Convertible Senior Notes due 2020 (the “2020 Convertible Notes”). In March 2015 the underwriters purchased 299,333 shares of common stock at $6.00 per share and $1,000 of the 2020 Convertible Notes pursuant to exercises of their overallotment options. The Company received net proceeds of $36,565 after deducting underwriting discounts and offering-related costs, from its equity issuances and  $18,903 in net proceeds, after deducting underwriting discounts and offering-related costs, from its debt issuances (see Note 4). Prior to this the Company has funded its operations primarily through the sale of preferred stock and issuance of convertible promissory notes and notes payable. As of March 31, 2015, the Company had an accumulated deficit of $129,503 and cash and cash equivalents of $53,139. The Company estimates that it has sufficient funding to sustain operations for 18 months.
	The Company will need to expend substantial resources for research and development, including costs associated with the clinical testing of its product candidates and will need to obtain additional financing to fund its operations and to conduct trials for its product candidates. If such products were to receive regulatory approval, the Company would need to prepare for the potential commercialization of its product candidates and fund the commercial launch and continued marketing of its products. The Company expects operating expenses will substantially increase in the future related to additional clinical testing and to support an increased infrastructure to support expanded operations and being a public company.
	The Company will require additional funding in the future and may not be able to raise such additional funds. The Company expects losses will continue as it conducts research and development activities. The Company will seek to finance future cash needs through public or private equity offerings, license agreements, debt financings, collaborations, strategic alliances, or any combination thereof. The incurrence of indebtedness would result in increased fixed payment obligations and could also result in restrictive covenants, such as limitations on our ability to incur additional debt, limitations on the Company’s ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact the ability of the Company to conduct its business. If adequate funds are not available, the Company would delay, reduce or eliminate research and development programs and reduce administrative expenses. The Company may seek to access the public or private capital markets whenever conditions are favorable, even if it does not have an immediate need for additional capital at that time. In addition, if the Company raises additional funds through collaborations, strategic alliances or licensing arrangements with third parties, it may have to relinquish valuable rights to its technologies, future revenue streams or product candidates or to grant licenses on terms that may not be favorable to it. If the Company is unable to raise sufficient funding, it may be unable to continue to operate. There is no assurance that the Company will be successful in obtaining sufficient financing on acceptable terms and conditions to fund continuing operations, if at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations and financial condition.

Significant_Accounting_Policie

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies
	Basis of Presentation—The Company’s interim financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). In the opinion of management, the Company has made all necessary adjustments, which include normal recurring adjustments necessary for a fair statement of the Company’s financial position and results of operations for the interim periods presented. Certain information and disclosures normally included in the annual financial statements prepared in accordance with GAAP have been condensed or omitted. These interim financial statements should be read in conjunction with the audited financial statements and accompanying notes for the year ended December 31, 2014 included in the Company’s Annual Report on Form 10-K. The results for the three months ended March 31, 2015 are not necessarily indicative of the results to be expected for a full year, any other interim periods or any future year or period.
	Use of Estimates—The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from these estimates. Significant items subject to such estimates and assumptions include the valuation of stock options used for the calculation of stock-based compensation, fair value of warrant liabilities and other derivative financial instruments, and calculation of accruals related to research and clinical development.
	Cash and Cash Equivalents—Cash and cash equivalents consists of bank deposits and money market accounts. Cash equivalents are carried at cost which approximates fair value due to their short-term nature and which the Company believes do not have a material exposure to credit risk. The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents.
	The Company maintains its cash and cash equivalent balances in the form of money market, savings or operating accounts with financial institutions that management believes are creditworthy. The Company’s cash and cash equivalent accounts, at times, may exceed federally insured limits. The Company has not experienced any losses in such accounts. The Company believes it is not exposed to any significant credit risk on cash and cash equivalents.
	Deferred Public Offering Costs—Deferred public offering costs, which consist primarily of direct, incremental legal, accounting, SEC and NASDAQ fees relating to the IPO and issuance of the 2020 Convertible Notes, were capitalized as a component of other assets in the accompanying balance sheet as of December 31, 2014. At December 31, 2014, the Company had $1,846 of deferred public offering costs. In the three months ended March 31, 2015, the Company incurred an additional $1,088 of public of offering costs and allocated $2,307 of the aggregate public offering costs to the equity offering and $627 to the debt offering which were recorded as deferred financing costs and are being amortized to interest expense over the term of the 2020 Convertible Notes.
	Deferred Financing Costs—Financing costs incurred in connection with the Company’s notes payable, convertible bridge notes and 2020 Convertible Notes were capitalized at the inception of the notes and are amortized over the term of the respective notes using the effective interest rate method. Amortization of deferred financing costs were $44 and $51 in the three months ended March 31, 2015 and 2014, respectively.
	Research and Development Costs—Research and development costs are charged to expense as incurred and include, but are not limited to:
		•		employee-related expenses including salaries, benefits, travel and stock-based compensation expense for research and development personnel;
		•		expenses incurred under agreements with contract research organizations that conduct clinical and preclinical studies, contract manufacturing organizations and consultants;
		•		costs associated with preclinical and development activities; and
		•		costs associated with regulatory operations.
	Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as accrued expenses, or prepaid expenses and other current assets, if the related services have not been provided.
	Stock-Based Compensation—The Company measures the cost of employee services received in exchange for an award of equity instruments based on the fair value of the award on the grant date. That cost is recognized on a straight-line basis over the period during which the employee is required to provide service in exchange for the award. The fair value of options on the date of grant is calculated using the Black-Scholes option pricing model based on key assumptions such as stock price, expected volatility and expected term. The Company’s estimates of these assumptions are primarily based on third-party valuations, historical data, peer company data and judgment regarding future trends and factors.
	The Company accounts for stock options issued to non-employees in accordance with the provisions of the Financial Accounting Standards Board (“FASB”) Accounting Standard Codification (“ASC”) 505-50, Equity-Based Payments to Non-employees, which requires valuing the stock options on their grant date and measuring such stock options at their current fair value as they vest.
	Fair Value Measurements—The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. ASC 820, Fair Value Measurements and Disclosures (“ASC 820”), establishes a hierarchy of inputs used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below:
	Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
	Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly.
	Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable.
	To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The fair value of the Company’s financial instruments, including cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their respective carrying values due to the short-term nature of these instruments. The Company’s assets and liabilities measured at fair value on a recurring basis include its warrant liabilities, convertible notes redemption rights derivative and 2020 Convertible Notes derivative (see Note 7).
	Derivative Financial Instruments—All derivatives are recorded as assets or liabilities at fair value, and the changes in fair value are immediately included in earnings, as the derivatives had not been formally designated as hedges for accounting purposes. The Company’s derivative financial instruments include bifurcated embedded derivatives that were identified within the 2020 Convertible Notes and the Convertible Bridge Notes (see Notes 4 and 8).
	Net loss per share—The Company calculates net loss per share in accordance with ASC 260, Earnings per Share. Basic earnings (loss) per share (“EPS”) is calculated by dividing the net income or loss applicable to common stockholders by the weighted average number of common shares outstanding for the period, without consideration of unissued common stock equivalents. The net loss applicable to common stockholders is determined by the reported net loss for the period and deducting dividends accrued and accretion of preferred stock. Diluted EPS is calculated by adjusting the weighted average common shares outstanding for the dilutive effect of common stock options, warrants, and convertible preferred stock and accrued but unpaid convertible preferred stock dividends. In periods where a net loss is recorded, no effect is given to potentially dilutive securities, as their effect would be anti-dilutive.
	The following table sets forth the computation of basic and diluted earnings (loss) per share attributable to the Company’s common stockholders:
			For the three months ended March 31,
			2015			2014
	Numerator:
	Net loss		$	(1,462	)	$	(2,148	)
	Accretion and dividends on convertible preferred stock			(130	)		(993	)
	Net loss applicable to common stockholders			(1,592	)		(3,141	)
	Denominator:
	Weighted average common shares outstanding—basic and diluted			7,677,575			1,020,088
	Net loss per share applicable to common stockholders—basic and diluted		$	(0.21	)	$	(3.08	)
	The following common stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated as including them would have an anti-dilutive effect:
			March 31,
			2015			2014
	Series AA preferred stock			—			6,906,170
	Series X preferred stock			—			466,319
	Share issuable upon conversion of the 2020 Convertible Notes			3,333,333			—
	Warrants for Series AA preferred stock			56,408			266,428
	Stock options			911,075			11,835
	Total			4,300,816			7,650,752
	Subsequent Events—The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The Company has completed an evaluation of all subsequent events through the date the financial statements were issued.

Accrued_Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Accrued Expenses	3. Accrued Expenses
	Accrued expenses at March 31, 2015 and December 31, 2014 consisted of the following:
		March 31,		December 31,
		2015		2014
	Research and development	$	18	$	116
	Government payable		429		421
	Compensation and benefits		345		293
	Professional fees		244		155
	Other		16		7
	Total	$	1,052	$	992

Debt

Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Debt	4. Debt
	2020 Convertible Notes
	On February 23, 2015, the Company issued an aggregate of $20,000 of the 2020 Convertible Notes pursuant to its IPO. On March 24, 2015, the Company issued an additional $1,000 of 2020 Convertible Notes pursuant to the exercise of the underwriters’ overallotment option. The 2020 Convertible Notes mature on February 15, 2020 (“Maturity Date”), are unsecured and accrue interest at a rate of 5.0% per annum, payable semi-annually on February 15 and August 15 of each year. In connection with the issuance of the 2020 Convertible Notes, the Company incurred $2,097 of financing costs which were recorded in other assets on the balance sheet at March 31, 2015.
	Each holder of a 2020 Convertible Note (the “Holder”), has the option to convert all or any portion of such note at an initial conversion rate of 158.7302 shares of the Company’s common stock per $1 principal amount of 2020 Convertible Notes (the “Conversion Rate”). The Conversion Rate is subject to adjustment from time to time upon the occurrence of certain events, including the issuance of stock dividends and payment of cash dividends. For any conversion that occurs on or after July 23, 2015, the Company will, in addition to the other consideration payable, make an interest make-whole payment (an “Interest Make-Whole Payment”) to such converting Holder equal to the sum of the present values of the scheduled payments of interest that would have been made on the notes to be converted had such notes remained outstanding from the date of the conversion (the “Conversion Date”) through the earlier of (i) the date that is three years after the Conversion Date and (ii) the Maturity Date if the Notes had not been so converted or otherwise repurchased. Present values for the Interest Make-Whole Payment will be calculated using a discount rate equal to 2%. The Company may satisfy its obligation to pay any Interest Make-Whole Payment, at its election, in cash, shares of common stock or a combination thereof.
	The 2020 Convertible Notes are convertible, at the holder’s option, upon a fundamental change (“Fundamental Change”), as defined in the Indenture (“Indenture”). If a holder elects to convert its notes upon a Fundamental Change, the Company shall increase the Conversion Rate for the Notes so surrendered for conversion by a number of additional shares of common stock by which the Conversion Rate shall be increased per $1 principal amount of notes for each stock price and make-whole Fundamental Change effective date as set forth in the Indenture. The additional shares range from 7.9364 to 0.
	Upon a Fundamental Change, each Holder shall have the right to require the Company to repurchase for cash all of such Holder’s notes, or any portion thereof that is equal to $1 or an integral multiple of $1. The repurchase price of the notes will equal 100% of the principal amount thereof, plus accrued and unpaid interest thereon. However, if the repurchase occurs after a regular record date for an interest payment, but before the distribution date of that interest payment, the Holder will receive the regular interest payment and the repurchase price will only equal 100% of the principal amount of the notes to be repurchased.
	The 2020 Convertible Notes can be redeemed at the holder’s option upon an event of default (“Event of Default”). If an Event of Default (other than certain events of bankruptcy, insolvency or reorganization involving the Company) occurs and is continuing, the Trustee by notice to the Company, or the holders of at least 25% in principal amount of the outstanding notes by written notice to the Company and the Trustee, may declare 100% of the principal and accrued and unpaid interest, if any, on all of the notes to be due and payable immediately. Upon the occurrence of certain Events of Default relating to bankruptcy, insolvency or reorganization involving the Company, 100% of the principal and accrued and unpaid interest, if any, on all of the notes will become due and payable automatically.
	The Indenture provides that, to the extent the Company elects and for up to 180 days, the sole remedy for an Event of Default relating to certain failures by the Company to comply with certain reporting covenants in the Indenture consists exclusively of the right to receive additional interest (“Additional Interest”) on the notes. The Additional Interest consists of interest at an additional rate of 0.25% per annum for the first 90 days after the Event of Default. For the 91st to 180th day after the Event of Default the Additional Interest shall consist of interest at an additional rate of 0.50% per annum. After 180 days, if the Event of Default is not cured or waived, the notes are subject to acceleration as provided in Section 6.02 of the Indenture.
	The Company determined that the conversion option and Interest Make-Whole Payments and the Additional Interest were embedded derivatives that require bifurcation and separate accounting under ASC 815, Derivatives and Hedging. Based on the characteristics of the (i) conversion option including make-whole provision, (ii) the Additional Interest, and (iii) the notes, we estimated the fair value of the conversion option including make-whole and the Additional Interest using the “with” and “without” method. Using this methodology, we first valued the notes with the conversion option including make-whole provision but excluding the Additional Interest (the “with” scenario) and subsequently valued the notes without the conversion option including make-whole provision and excluding the Additional Interest (the “without” scenario). The difference between the fair values of the notes in the “with” and “without” scenarios was the concluded fair value of the conversion option including make-whole provision as of the measurement date. We developed an estimate of fair value for the 2020 Convertible Notes excluding the Additional Interest using a binomial lattice model. We modeled the decision to convert or hold by considering the maximum of the conversion or hold value at every node of the lattice in which the notes are convertible and choosing the action that maximizes the return to the notes’ holders. The significant assumptions used in the binomial model were: the market yield and the expected volatility.
	We estimated the fair value of the Additional Interest using an income approach, specifically, the risk-neutral debt valuation method that is used to derive the value of a debt instrument using the expected cash flows and the risk-free rate. The significant assumptions used in estimating the expected cash flows were the market yield used to determine the risk-neutral probability of default and the expected recovery rate upon default.
	The Company recorded $11,850 as the fair value of the combined embedded derivative liability on February 23, 2015, with a corresponding amount recorded as a discount to the 2020 Convertible Notes, related to the initial issuance of the 2020 Convertible Notes. The Company recorded approximately $573 of additional derivative liability and discount to the notes as the fair value of the combined embedded derivative on March 24, 2015 upon the issuance of additional 2020 Convertible Notes for the exercise of the underwriters’ overallotment option. The deferred financing costs which are recorded in other assets are being amortized to interest expense over the life of the 2020 Convertible Notes using the effective interest method. Changes in the fair value of the combined embedded derivative liability are recorded in earnings in the period in which the changes occur. As of March 31, 2015, the fair value of the combined embedded derivative liability was $10,426. The change in the estimated fair value of the combined embedded derivative liability of $1,997 was recorded in earnings in the three months ended March 31, 2015. Interest expense related to the 2020 Convertible Notes for the three months ended March 31, 2015 was $209, including $105 related to amortization of the issuance costs. As of March 31, 2015, the balance of debt discount and issuance costs were $12,333 and $2,082, respectively. At March 31, 2015, interest accrued on the 2020 Convertible Notes was $104 and is reflected in accrued interest on the balance sheet.
	The following table summarizes how the issuance of the 2020 Convertible Notes are reflected on the balance sheet at March 31, 2015:
		March 31, 2015
	Gross proceeds	$	21,000
	Initial value of embedded derivatives		(12,423	)
	Amortization of debt discount		90
	Carrying value	$	8,667
	Convertible Bridge Notes
	In December 2014, the Company sold an aggregate of $2,000 of subordinated convertible promissory notes to existing stockholders (the “Convertible Bridge Notes”). The Convertible Bridge Notes mature on June 30, 2015 and accrue interest at the rate of 8% per annum and are subordinate to all other senior indebtedness of the Company. Upon the closing of an IPO of common stock of at least $40,000 in gross proceeds, all outstanding principal and accrued interest thereon will automatically convert into common stock at the IPO price.
	Pursuant to the IPO in February 2015, the Convertible Bridge Notes were converted into 337,932 shares of common stock based upon the IPO common share offering price of $6.00. During the three months ended March 31, 2015, the Company reflected as interest expense related to the Convertible Bridge Notes (i) $23 related to the 8% coupon rate and (ii) $128 of amortization of the initial fair value of the redemption rights derivative and issuance costs. In connection with the conversion of the Convertible Bridge Notes into common stock, the Company recorded a (i) a $480 gain in change in fair value of the of the Convertible Bridge Notes redemption rights derivative from the write off of the derivative and (ii) a loss on extinguishment of debt of $360 from the acceleration of the unamortized balance of the debt discount and issuance costs.
	Notes Payable
	On June 28, 2013, the Company entered into two Loan and Security Agreements (the “Loan Agreements” or “Loans”) with two financial entities (the “Lenders”) pursuant to which the Company issued Loans for $3,500 to each lender and received proceeds of $6,915 net of costs and fees payable to the lenders. The Loans bear interest at a rate per annum of 11.0%. The Loans mature on October 1, 2016 and required interest-only payments for the initial 12 months and thereafter required repayment of the principal balance with interest in 27 monthly installments. Also, upon full repayment or maturity of the Loans, the Lenders are due a termination payment of 3.0% of the initial principal amount of the Loans, or $210 (the “Loan Termination Payment”).
	In connection with the Loan Agreements, the Company issued to the Lenders fully-vested warrants to purchase either, at the election of the warrant holder, (i) 228,906 shares of the Company’s Series AA preferred stock at an exercise price of $1.529 per share, or (ii) $350 of stock in the next round stock, as defined in the Loan Agreements, at a price that is the lowest effective price per share that is offered in the next round. The warrants expire on the earlier of (i) ten years after the date of grant, or (ii) immediately prior to an acquisition transaction, as defined in the warrants. The Company determined that the warrants should initially be classified as a liability based upon the nature of the underlying Series AA preferred stock.
	In connection with the Company’s IPO in February 2015, the Company exercised its right to terminate the Loan Agreements by paying the $5,347 principal balance due, the $210 Loan Termination Payment, a $160 prepayment fee calculated as 3% of the principal balance due at the time of the termination, plus $23 of interest accrued from February 1, 2015 through the payoff date. The Company made a scheduled principal payment of $243 in January 2015.
	For the three months ended March 31, 2015, interest expense related to the Loan Agreements was $115, including $26 related to accretion of the debt discount and termination payment. Additionally in the three months ended March 31, 2015, the Company recorded a charge for loss on extinguishment of debt of $322 related to the write-off of the unamortized debt discount.
	For the three months ended March 31, 2014, interest expense related to the Loan Agreements was $243, including $51 related to accretion of the debt discount and termination payment.
	Subsequent to the Company’s IPO, the warrants issued to the lenders became exercisable for 56,408 shares of common stock at $6.204 per share. The Company calculated the fair value of the warrants at the IPO date using a Black Scholes model using the following assumptions: a fair value of $6.00 per share (the IPO price of the Company’s common stock), 8.4 years to maturity, 1.70% risk-free rate, and 60% volatility. The Company determined the fair value as of the warrant liability at the IPO date to be $215 and recorded a gain on change in fair value of warrant liabilities of $267 in the statement of operations for the three months ended March 31, 2015. The Company determined that subsequent to this change, the warrants were exercisable at a fixed price for a fixed number of shares of common stock and qualified for equity classification under the accounting guidance, and the fair value of $215 was reclassified to additional paid-in capital as of the IPO date during the three months ended March 31, 2015.

Equity

Equity	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Equity	5. Equity
	Authorized Shares
	As of December 31, 2014, the authorized stock of the Company was 43,509,727 shares of common stock, $0.01 par value per share, and 28,659,924 shares of preferred stock, $0.001 par value per share, of which 25,757,874 shares are authorized Series AA redeemable convertible preferred stock (the “Series AA preferred stock”) and 2,902,050 shares are authorized as Series X redeemable convertible preferred stock (the “Series X preferred stock”) (collectively, the “Preferred Stock”).
	In February 2015, the Company’s board of directors and stockholders approved an amendment of the Company’s certificate of incorporation such that upon the closing of the IPO, the Company’s authorized capital stock will consist of 120,000,000 shares of common stock, par value $0.01 per share, and 5,000,000 shares of undesignated preferred stock, par value $0.001 per share.
	Reverse Stock Splits
	In November 2014, the board of directors and the stockholders of the Company approved a 1-for-3.39 reverse stock split of the Company’s outstanding common stock and in January 2015, the board of directors and the stockholders of the Company approved a 1-for-1.197 reverse stock split of the Company’s outstanding common stock. Shares of common stock underlying outstanding stock options were proportionally reduced and the respective exercise prices were proportionally increased in accordance with the terms of the option agreements. The Company’s historical share and per share information has been retroactively adjusted in the financial statements presented to give effect to these reverse stock splits, including reclassifying an amount equal to the reduction in par value to additional paid-in capital.
	Preferred Stock
	Pursuant to the IPO, all of the Company’s outstanding 25,949,333 shares of Series AA and Series X preferred stock, including all accrued and unpaid dividends thereon, automatically converted into 8,002,650 shares of common stock. Pursuant to the conversion, the $46,383 carrying value of the Series AA preferred stock at the time of the IPO was reclassified as $75 to common stock par value and $46,308 additional paid-in capital and the $548 carrying value of the Series X preferred stock at the time of the IPO was reclassified as $5 to common stock par value and $543 additional paid-in capital.
	During the year ended December 31, 2014, the Company modified the terms of 558,862 shares of Series X preferred stock such that the Company’s repurchase right relative to those shares expired upon consummation of the IPO. The Company estimated the fair value of the modified award at the modification date to be $950 and recognized this amount as stock-based compensation expense in the three months ended March 31, 2015.
	Common Stock
	All preferences, voting powers, relative, participating, optional, or other specific rights and privileges, limitations, or restrictions of the common stock are expressly subject to those that may be fixed with respect to any shares of preferred stock. Common stockholders are entitled to one vote per share, and to receive dividends, when and if declared by the Board. At March 31, 2015 and December 31, 2014, there were 16,327,003 and 1,020,088 shares common stock outstanding, respectively.
	2014 Stock Option and Incentive Plan
	In August 2014, the Company’s board of directors adopted the 2014 Stock Option and Incentive Plan (the “2014 Plan”) for the issuance of incentive and non-qualified stock options, restricted stock, and other equity awards, all for common stock, as determined by the board of directors to employees, officers, directors, consultants, and advisors of the Company and its subsidiaries. In November 2014, the Board of Directors increased the number of shares available for grant under the terms of the 2014 Plan to the number of shares that represents 13.7% of the outstanding common stock after giving effect to the issuance of shares relating to the Company’s then-proposed IPO (not including any shares purchased by the underwriters pursuant to their overallotment option). Subsequent to the IPO in February 2015, there were 2,175,216 shares available for grant under the 2014 Plan. The 2014 Plan expires in August 2024.
	On August 28, 2014, the Board of Directors granted 840,975, ten-year term, stock options to officers of the Company at an exercise price of $4.342 per share, the fair market value of the common stock as determined by the Board of Directors, on the condition that the options would be of no further force and effect if the Company had not consummated an IPO prior to the one-year anniversary of the grant date (the “IPO Condition”). The IPO Condition was met upon the Company’s February 2015 IPO. These stock options will vest 25% on the one-year anniversary of the grant date and remaining 75% will vest equally over the following 35 monthly anniversaries. Additionally on August 28, 2014, the Board of Directors granted 59,142 stock options that were fully vested on the date of the grant.
	The fair value of each stock option granted was estimated on the grant date using a Black-Scholes stock option pricing model based on the following assumptions: an expected term of 5 to 6.25 years; expected stock price volatility of 83.3% to 92.5%; a risk free rate of 1.63% to 1.84%; and a dividend yield of 0%. The Company will recognize $2,798 of stock-based compensation expense for these stock options on a straight-line basis commencing upon the grant date in August 2014 through the final vesting date in August 2018. As a result of the resolution of the IPO Condition, the three months ended March 31, 2015 reflects stock compensation expense calculated from the grant date in August 2014 through March 31, 2015. The Company recorded an aggregate stock compensation expense of $414 for these stock options, $218 in general and administrative expense and $196 in research and development expense, in the three months ended March 31, 2015.
	The following table summarizes activity for the three months ended March 31, 2015 under the 2014 Plan:
		Number of Shares		Weighted Average		Aggregate
				Exercise Price Per		Intrinsic Value
				Share
	Options outstanding at December 31, 2014		900,117	$	4.342	$	970
	Granted during the period		—		—
	Exercised during the period		—		—
	Expired during the period		—		—
	Options outstanding at March 31, 2015		900,117	$	4.342	$	970
	Options exercisable at March 31, 2015		59,142	$	4.342	$	64
	Weighted-average years remaining on contractual life		9.4
	Unrecognized compensation cost related to non-vested stock options	$	2,384
	Aggregate intrinsic value is based on $5.42 per share, the closing price of common stock on March 31, 2015.
	The Company has outstanding stock options pursuant to its 2004 Stock Option and Incentive Plan. The following table summarizes activity for the three months ended March 31, 2015 under the 2004 Plan:
		Number of Shares		Weighted Average		Aggregate
				Exercise Price Per		Intrinsic Value
				Share
	Options outstanding at December 31, 2014		10,958	$	40.578	$	—
	Granted during the period		—		—
	Exercised during the period		—		—
	Expired during the period		—		—
	Options outstanding at March 31, 2015		10,958	$	40.578	$	—
	Options exercisable at March 31, 2015		10,958	$	40.578	$	—
	Weighted-average years remaining on contractual life		3
	Unrecognized compensation cost related to non-vested stock options	$	—
	The exercise price exceeds the $5.42 closing price of common stock on March 31, 2015, therefore there is no intrinsic value of the outstanding 2004 Plan stock options.
	Employee Stock Purchase Plan
	In November 2014 the Company’s board of directors adopted and the stockholders approved the 2014 Employee Stock Purchase Plan, or ESPP. The Company’s board of directors has authorized the issuance of a number of shares of common stock issuable under the ESPP to the number that represents 1% of our outstanding common stock outstanding after the IPO, or 160,276 shares. The ESPP provides that the number of shares reserved and available for issuance under the ESPP shall be cumulatively increased each January 1, beginning on January 1, 2016, by the lesser of (i) 600,000 shares of common stock or (ii) the number of shares necessary to set the number of shares of Common Stock under the Plan at 1% percent of the outstanding number of shares as of January 1 of the applicable year. However, the board of directors reserves the right to determine that there will be no increase for any year or that any increase will be for a lesser number of shares. As of March 31, 2015, no shares have been issued pursuant to the ESPP.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies
	Operating leases
	The Company leases office space in Lexington, Massachusetts under a lease agreement expiring in September 2015. Rent expense for each of the three months ended March 31, 2015 and 2014 was $15. The Company is committed to pay approximately $43 under the terms of the lease from April 1, 2015 through September 2015.
	Indemnification Arrangements
	As permitted under Delaware law, the Company’s bylaws provide that the Company will indemnify any director, officer, employee or agent of the Company or anyone serving in these capacities. The maximum potential amount of future payments the Company could be required to pay is unlimited. The Company has insurance that reduces its monetary exposure and would enable it to recover a portion of any future amounts paid. As a result, the Company believes that the estimated fair value of these indemnification commitments is minimal.
	Throughout the normal course of business, the Company has agreements with vendors that provide goods and services required by the Company to run its business. In some instances, vendor agreements include language that requires the Company to indemnify the vendor from certain damages caused by the Company’s use of the vendor’s goods and/or services. The Company has insurance that would allow it to recover a portion of any future amounts that could arise from these indemnifications. As a result, the Company believes that the estimated fair value of these indemnification commitments is minimal.

Fair_Value_of_Financial_Measur

Fair Value of Financial Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Measurements	7. Fair Value of Financial Measurements
	Items measured at fair value on a recurring basis are convertible preferred stock warrant liabilities, the convertible bridge notes redemption rights derivative and the 2020 Convertible Notes derivative.
	The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy:
		Fair Value Measurements at
		31-Mar-15
		Total			Level 1			Level 2			Level 3
	Liabilities:
	2020 Convertible Notes derivative	$	10,426		$	—		$	—		$	10,426
		Fair Value Measurements at
		31-Dec-14
		Total			Level 1			Level 2			Level 3
	Liabilities:
	Convertible preferred stock warrant liability	$	482		$	—		$	—		$	482
	Convertible bridge notes redemption rights derivative	$	480		$	—		$	—		$	480
	2020 Convertible Notes Derivative
	The fair value methodologies related to the 2020 Convertible Notes derivative are discussed in Note 4.
	Convertible preferred stock warrant liability
	As of December 31, 2013, March 31, 2014 and December 31, 2014, the Company had outstanding warrants to purchase Series AA preferred stock in connection with Series AA preferred stock issued in 2013 and the Loan Agreements. The Series AA warrant liabilities were recorded at their fair value on the date of issuance and are remeasured on each subsequent balance sheet date and as of the warrant exercise date, with fair value changes recognized as income (decrease in fair value) or expense (increase in fair value) in other income (expense) in the statements of operations.
	As of December 31, 2013, March 31, 2014 and December 31, 2014, the Company used a hybrid valuation model in which a Monte Carlo simulation was used to calculate the fair value of the Company’s equity securities under three scenarios including: (i) an IPO scenario, (ii) a merger or acquisition scenario or (iii) a stay private scenario. The Company then probability-weighted each equity value derived from the Monte Carlo simulation based upon the Company’s estimate of the likelihood of the exit scenario occurring.
	The assumptions used in calculating the estimated fair value of the warrants represent the Company’s best estimates and include probabilities of settlement scenarios, enterprise value, time to liquidity, risk-free interest rates, discount for lack of marketability and volatility. The estimates are based, in part, on subjective assumptions and could differ materially in the future. Generally, increases or decreases in the fair value of the underlying convertible preferred stock would result in a directionally similar impact in the fair value measurement of the warrant liability. The following table details the assumptions used in the Monte Carlo simulation models used to estimate the fair value of the Series AA preferred stock warrants at December 31, 2013, March 31, 2014 and December 31, 2014:
		December 31, 2013			March 31, 2014			December 31, 2014
	Volatility		60	%		65	%		65% - 70	%
	Expected term (years)		1.00 - 1.25			0.50 - 0.75			0.17 - 0.50
	Expected dividend yield		0	%		0	%		0	%
	Risk-free rate		0.13 - 0.19	%		0.06% - 0.09	%		0.02% - 0.03	%
	In addition to the assumptions above, the Company’s estimated fair value of the Series AA preferred stock warrant liabilities is calculated using other key assumptions including the probability of an exit event, the enterprise value as determined on an income approach, and a discount for lack of marketability. Management, with the assistance of an independent valuation firm, made these subjective determinations based on available current information. (See Note 4 of Notes to Financial Statements.)
	Convertible Bridge Notes redemption rights derivative liability
	The Convertible Bridge Notes redemption rights derivative required separate accounting and was valued using a single income valuation approach. The Company estimated the fair value of the redemption rights derivative using a ‘‘with and without’’ income valuation approach. Under this approach, the Company estimated the present value of the fixed interest rate debt based on the fair value of similar debt instruments excluding the embedded feature. This amount was then compared to the fair value of the debt instrument including the embedded feature using a probability weighted approach by assigning each embedded derivative feature a probability of occurrence, with consideration provided for the settlement amount including conversion discounts, prepayment penalties, the expected life of the liability and the applicable discount rate.
	As of December 31, 2014, the Company ascribed a probability of occurrence to the Change in Control Redemption Feature of 25%. The expected life of the feature was the remaining term of the debt and the discount rate was 18.9%. The Company classified the liability within Level 3 of the fair value hierarchy as the probability factor and the discount rate are unobservable inputs and significant to the valuation model. As of December 31, 2014, the fair value of the embedded derivative was $480. Pursuant to the IPO, the Convertible Bridge Notes were redeemed.
	During the periods presented, the Company has not changed the manner in which it values liabilities that are measured at fair value using Level 3 inputs. The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. There were no transfers within the hierarchy during any of the years presented.
	The following table reflects the change in the Company’s Level 3 liabilities for the three months ended March 31, 2015 and 2014:
		Preferred stock			Convertible bridge notes			2020 Convertible Notes
		warrant liabilities			redemption rights			derivative liability
					derivative liability
	Balance at December 31, 2014	$	482		$	480		$	—
	Issuance of 2020 Convertible Notes		—			—			12,423
	Change in fair value		(267	)		(480	)		(1,997	)
	Reclassification to stockholders’ equity		(215	)		—			—
	Balance at March 31, 2015	$	—		$	—		$	10,426
	Balance at December 31, 2013	$	1,888		$	—		$	—
	Change in fair value		193			—			—
	Balance at March 31, 2014	$	2,081		$	—		$	—

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Note 8. Derivative Financial Instruments
	The Company determined that certain embedded features related to the 2020 Convertible Notes and the Convertible Bridge Notes are derivative financial instruments.
	Fair values of derivative instruments not designated as hedging instruments consist of the following:
	Liability derivatives:	Balance Sheet Location	Fair Value
	December 31, 2014:
	Convertible Bridge Notes redemption rights derivative	Convertible Bridge Notes redemption rights derivative	$	480
	March 31, 2015:
	2020 Convertible Notes derivative	2020 Convertible Notes derivative	$	10,426
	The effect of derivative instruments not designated as hedging instruments on the statement of operations for the three months ended March 31, 2015 consist of the following:
	Derivatives not	Location of gain or loss		Amount of gain
	designated as			or (loss)
	hedging instruments	recognized in income on		recognized in
				income on
		derivative		derivative
	2020 Convertible	Change in fair value of 2020	$	1,997
	Notes derivative	Convertible Notes derivative
	Convertible Bridge	Change in fair value of	$	480
	Notes	Convertible Bridge Notes
		redemption rights derivative
	See Notes 4 and 7 for additional discussion regarding the accounting for and valuation of these derivative financial instruments.

Management_Incentive_Plan

Management Incentive Plan	3 Months Ended
	Mar. 31, 2015
Compensation Related Costs [Abstract]
Management Incentive Plan	9. Management Incentive Plan
	In August 2014, the Company adopted the Amended and Restated 2014 Management Incentive Plan (the “MIP”) in which certain of our named executive officers participate. Pursuant to the MIP, upon a “change in control” (as defined in the MIP), a bonus pool will be created from the proceeds received in connection with such change in control (ranging from 7 percent to 9.75 percent of transaction proceeds, depending upon the level of transaction proceeds received in the transaction), and each participant is entitled to receive a bonus equal to a certain percentage of such bonus pool. The MIP terminated automatically upon the IPO in February 2015.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events
	The Company has completed an evaluation of all subsequent events through the date these financial statements were issued and has concluded there are no subsequent events to report.

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation—The Company’s interim financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). In the opinion of management, the Company has made all necessary adjustments, which include normal recurring adjustments necessary for a fair statement of the Company’s financial position and results of operations for the interim periods presented. Certain information and disclosures normally included in the annual financial statements prepared in accordance with GAAP have been condensed or omitted. These interim financial statements should be read in conjunction with the audited financial statements and accompanying notes for the year ended December 31, 2014 included in the Company’s Annual Report on Form 10-K. The results for the three months ended March 31, 2015 are not necessarily indicative of the results to be expected for a full year, any other interim periods or any future year or period.
Use of Estimates	Use of Estimates—The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from these estimates. Significant items subject to such estimates and assumptions include the valuation of stock options used for the calculation of stock-based compensation, fair value of warrant liabilities and other derivative financial instruments, and calculation of accruals related to research and clinical development.
Cash and Cash Equivalents	Cash and Cash Equivalents—Cash and cash equivalents consists of bank deposits and money market accounts. Cash equivalents are carried at cost which approximates fair value due to their short-term nature and which the Company believes do not have a material exposure to credit risk. The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents.
	The Company maintains its cash and cash equivalent balances in the form of money market, savings or operating accounts with financial institutions that management believes are creditworthy. The Company’s cash and cash equivalent accounts, at times, may exceed federally insured limits. The Company has not experienced any losses in such accounts. The Company believes it is not exposed to any significant credit risk on cash and cash equivalents.
Deferred Public Offering Costs	Deferred Public Offering Costs—Deferred public offering costs, which consist primarily of direct, incremental legal, accounting, SEC and NASDAQ fees relating to the IPO and issuance of the 2020 Convertible Notes, were capitalized as a component of other assets in the accompanying balance sheet as of December 31, 2014. At December 31, 2014, the Company had $1,846 of deferred public offering costs. In the three months ended March 31, 2015, the Company incurred an additional $1,088 of public of offering costs and allocated $2,307 of the aggregate public offering costs to the equity offering and $627 to the debt offering which were recorded as deferred financing costs and are being amortized to interest expense over the term of the 2020 Convertible Notes.
Deferred Financing Costs	Deferred Financing Costs—Financing costs incurred in connection with the Company’s notes payable, convertible bridge notes and 2020 Convertible Notes were capitalized at the inception of the notes and are amortized over the term of the respective notes using the effective interest rate method. Amortization of deferred financing costs were $44 and $51 in the three months ended March 31, 2015 and 2014, respectively.
Research and Development Costs	Research and Development Costs—Research and development costs are charged to expense as incurred and include, but are not limited to:
		•		employee-related expenses including salaries, benefits, travel and stock-based compensation expense for research and development personnel;
		•		expenses incurred under agreements with contract research organizations that conduct clinical and preclinical studies, contract manufacturing organizations and consultants;
		•		costs associated with preclinical and development activities; and
		•		costs associated with regulatory operations.
	Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as accrued expenses, or prepaid expenses and other current assets, if the related services have not been provided.
Stock-Based Compensation	Stock-Based Compensation—The Company measures the cost of employee services received in exchange for an award of equity instruments based on the fair value of the award on the grant date. That cost is recognized on a straight-line basis over the period during which the employee is required to provide service in exchange for the award. The fair value of options on the date of grant is calculated using the Black-Scholes option pricing model based on key assumptions such as stock price, expected volatility and expected term. The Company’s estimates of these assumptions are primarily based on third-party valuations, historical data, peer company data and judgment regarding future trends and factors.
	The Company accounts for stock options issued to non-employees in accordance with the provisions of the Financial Accounting Standards Board (“FASB”) Accounting Standard Codification (“ASC”) 505-50, Equity-Based Payments toNon-employees, which requires valuing the stock options on their grant date and measuring such stock options at their current fair value as they vest.
Fair Value Measurements	Fair Value Measurements—The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. ASC 820, Fair Value Measurements and Disclosures(“ASC 820”), establishes a hierarchy of inputs used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below:
	Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
	Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly.
	Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable.
	To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The fair value of the Company’s financial instruments, including cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their respective carrying values due to the short-term nature of these instruments. The Company’s assets and liabilities measured at fair value on a recurring basis include its warrant liabilities, convertible notes redemption rights derivative and 2020 Convertible Notes derivative (see Note 7).
Derivative Financial Instruments	Derivative Financial Instruments—All derivatives are recorded as assets or liabilities at fair value, and the changes in fair value are immediately included in earnings, as the derivatives had not been formally designated as hedges for accounting purposes. The Company’s derivative financial instruments include bifurcated embedded derivatives that were identified within the 2020 Convertible Notes and the Convertible Bridge Notes (see Notes 4 and 8).
Net loss per share	Net loss per share—The Company calculates net loss per share in accordance with ASC 260, Earnings per Share. Basic earnings (loss) per share (“EPS”) is calculated by dividing the net income or loss applicable to common stockholders by the weighted average number of common shares outstanding for the period, without consideration of unissued common stock equivalents. The net loss applicable to common stockholders is determined by the reported net loss for the period and deducting dividends accrued and accretion of preferred stock. Diluted EPS is calculated by adjusting the weighted average common shares outstanding for the dilutive effect of common stock options, warrants, and convertible preferred stock and accrued but unpaid convertible preferred stock dividends. In periods where a net loss is recorded, no effect is given to potentially dilutive securities, as their effect would be anti-dilutive.
	The following table sets forth the computation of basic and diluted earnings (loss) per share attributable to the Company’s common stockholders:
			For the three months ended March 31,
			2015			2014
	Numerator:
	Net loss		$	(1,462	)	$	(2,148	)
	Accretion and dividends on convertible preferred stock			(130	)		(1,001	)
	Net loss applicable to common stockholders			(1,592	)		(3,149	)
	Denominator:
	Weighted average common shares outstanding—basic and diluted			7,677,575			1,020,088
	Net loss per share applicable to common stockholders—basic and Diluted		$	(0.21	)	$	(3.09	)
	The following common stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated as including them would have an anti-dilutive effect:
			March 31,
			2015			2014
	Series AA preferred stock			—			6,906,170
	Series X preferred stock			—			466,319
	Share issuable upon conversion of the 2020 convertible notes			3,333,333			—
	Warrants for Series AA preferred stock			56,408			266,428
	Stock options			911,075			11,835
	Total			4,300,816			7,650,752
Subsequent Events	Subsequent Events—The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The Company has completed an evaluation of all subsequent events through the date the financial statements were issued.

Significant_Accounting_Policie2

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Schedule of Computation of Basic and Diluted Earnings (Loss) Per Share	The following table sets forth the computation of basic and diluted earnings (loss) per share attributable to the Company’s common stockholders:
		For the three months ended March 31,
		2015			2014
	Numerator:
	Net loss	$	(1,462	)	$	(2,148	)
	Accretion and dividends on convertible preferred stock		(130	)		(993	)
	Net loss applicable to common stockholders		(1,592	)		(3,141	)
	Denominator:
	Weighted average common shares outstanding—basic and diluted		7,677,575			1,020,088
	Net loss per share applicable to common stockholders—basic and diluted	$	(0.21	)	$	(3.08	)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following common stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated as including them would have an anti-dilutive effect:
		March 31,
		2015			2014
	Series AA preferred stock		—			6,906,170
	Series X preferred stock		—			466,319
	Share issuable upon conversion of the 2020 Convertible Notes		3,333,333			—
	Warrants for Series AA preferred stock		56,408			266,428
	Stock options		911,075			11,835
	Total		4,300,816			7,650,752

Accrued_Expenses_Tables

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Schedule of Accrued Expenses
	Accrued expenses at March 31, 2015 and December 31, 2014 consisted of the following:
		March 31,		December 31,
		2015		2014
	Research and development	$	18	$	116
	Government payable		429		421
	Compensation and benefits		345		293
	Professional fees		244		155
	Other		16		7
	Total	$	1,052	$	992

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Summary of Issuance of Convertible Notes	The following table summarizes how the issuance of the 2020 Convertible Notes are reflected on the balance sheet at March 31, 2015:
		March 31, 2015
	Gross proceeds	$	21,000
	Initial value of embedded derivatives		(12,423	)
	Amortization of debt discount		90
	Carrying value	$	8,667

Equity_Tables

Equity (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Summary of Stock Option Activity	The following table summarizes activity for the three months ended March 31, 2015 under the 2014 Plan:
		Number of Shares		Weighted Average		Aggregate
				Exercise Price Per		Intrinsic Value
				Share
	Options outstanding at December 31, 2014		900,117	$	4.342	$	970
	Granted during the period		—		—
	Exercised during the period		—		—
	Expired during the period		—		—
	Options outstanding at March 31, 2015		900,117	$	4.342	$	970
	Options exercisable at March 31, 2015		59,142	$	4.342	$	64
	Weighted-average years remaining on contractual life		9.4
	Unrecognized compensation cost related to non-vested stock options	$	2,384
	Aggregate intrinsic value is based on $5.42 per share, the closing price of common stock on March 31, 2015.
	The Company has outstanding stock options pursuant to its 2004 Stock Option and Incentive Plan. The following table summarizes activity for the three months ended March 31, 2015 under the 2004 Plan:
		Number of Shares		Weighted Average		Aggregate
				Exercise Price Per		Intrinsic Value
				Share
	Options outstanding at December 31, 2014		10,958	$	40.578	$	—
	Granted during the period		—		—
	Exercised during the period		—		—
	Expired during the period		—		—
	Options outstanding at March 31, 2015		10,958	$	40.578	$	—
	Options exercisable at March 31, 2015		10,958	$	40.578	$	—
	Weighted-average years remaining on contractual life		3
	Unrecognized compensation cost related to non-vested stock options	$	—

Fair_Value_of_Financial_Measur1

Fair Value of Financial Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value of Liabilities Measured on Recurring Basis	The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy:
		Fair Value Measurements at
		31-Mar-15
		Total			Level 1			Level 2			Level 3
	Liabilities:
	2020 Convertible Notes derivative	$	10,426		$	—		$	—		$	10,426
		Fair Value Measurements at
		31-Dec-14
		Total			Level 1			Level 2			Level 3
	Liabilities:
	Convertible preferred stock warrant liability	$	482		$	—		$	—		$	482
	Convertible bridge notes redemption rights derivative	$	480		$	—		$	—		$	480
Schedule of Assumptions Used to Estimate Fair Value of Series AA Preferred Stock Warrants	The following table details the assumptions used in the Monte Carlo simulation models used to estimate the fair value of the Series AA preferred stock warrants at December 31, 2013, March 31, 2014 and December 31, 2014:
		December 31, 2013			March 31, 2014			December 31, 2014
	Volatility		60	%		65	%		65% - 70	%
	Expected term (years)		1.00 - 1.25			0.50 - 0.75			0.17 - 0.50
	Expected dividend yield		0	%		0	%		0	%
	Risk-free rate		0.13 - 0.19	%		0.06% - 0.09	%		0.02% - 0.03	%
Schedule of Change in Company's Level 3 Liabilities	The following table reflects the change in the Company’s Level 3 liabilities for the three months ended March 31, 2015 and 2014:
		Preferred stock			Convertible bridge notes			2020 Convertible Notes
		warrant liabilities			redemption rights			derivative liability
					derivative liability
	Balance at December 31, 2014	$	482		$	480		$	—
	Issuance of 2020 Convertible Notes		—			—			12,423
	Change in fair value		(267	)		(480	)		(1,997	)
	Reclassification to stockholders’ equity		(215	)		—			—
	Balance at March 31, 2015	$	—		$	—		$	10,426
	Balance at December 31, 2013	$	1,888		$	—		$	—
	Change in fair value		193			—			—
	Balance at March 31, 2014	$	2,081		$	—		$	—

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Fair Values of Derivative Instruments Not Designated as Hedging Instruments	Fair values of derivative instruments not designated as hedging instruments consist of the following:
	Liability derivatives:	Balance Sheet Location		Fair Value
	December 31, 2014:
	Convertible Bridge Notes redemption rights derivative	Convertible Bridge Notes redemption rights derivative		$	480
	March 31, 2015:
	2020 Convertible Notes derivative	2020 Convertible Notes derivative		$
					10,426
Effect of Derivative Instrument Not Designated as Hedging Instruments on Statement of Operations	The effect of derivative instruments not designated as hedging instruments on the statement of operations for the three months ended March 31, 2015 consist of the following:
	Derivatives not		Location of gain or loss				Amount of gain
	designated as		recognized in income on				or (loss)
	hedging instruments		derivative				recognized in
							income on
							derivative
	2020 Convertible		Change in fair value of			$	1,997
	Notes derivative		2020 Convertible Notes
			derivative
	Convertible Bridge		Change in fair value of			$	480
	Notes		Convertible Bridge Notes
			redemption rights derivative

Organization_and_Operations_Ad

Organization and Operations - Additional Information (Detail) (USD $)	3 Months Ended	1 Months Ended
	Mar. 31, 2015	Feb. 28, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Schedule Of Description Of Business [Line Items]
Net proceeds from issuance of equity	$36,565,000
Net proceeds from issuance of debts	18,903,000
Accumulated deficit	-129,503,000		-128,041,000
Cash and cash equivalents	53,139,000		3,618,000	10,938,000	12,793,000
Estimated period of available funds to run normal organizational operations	18 months
Senior Notes [Member]
Schedule Of Description Of Business [Line Items]
Convertible Senior Notes, Stated percentage		5.00%
Aggregate principal amount		20,000,000
IPO [Member]
Schedule Of Description Of Business [Line Items]
Initial public offering common stock, shares		6,667,000
Initial public offering common stock, per shares		$6
Over-Allotment Option [Member]
Schedule Of Description Of Business [Line Items]
Initial public offering common stock, shares	299,333
Initial public offering common stock, per shares	$6
Over-Allotment Option [Member] | Senior Notes [Member]
Schedule Of Description Of Business [Line Items]
Aggregate principal amount	$1,000,000

Significant_Accounting_Policie3

Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Summary Of Significant Accounting Policy [Line Items]
Deferred public offering costs	$1,088		$1,846
Amortization of deferred financing costs	44	51
Equity Offering [Member]
Summary Of Significant Accounting Policy [Line Items]
Deferred public offering costs	2,307
Debt Offering [Member]
Summary Of Significant Accounting Policy [Line Items]
Deferred public offering costs	$627

Significant_Accounting_Policie4

Significant Accounting Policies - Schedule of Computation of Basic and Diluted Earnings (Loss) Per Share (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Numerator:
Net loss	($1,462)	($2,148)
Accretion and dividends on convertible preferred stock	-130	-993
Net loss applicable to common stockholders	($1,592)	($3,141)
Denominator:
Weighted average common shares outstanding-basic and diluted	7,677,575	1,020,088
Net loss per share applicable to common stockholders-basic and diluted	($0.21)	($3.08)

Significant_Accounting_Policie5

Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail)	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	4,300,816	7,650,752
Series AA Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		6,906,170
Series X Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		466,319
Share Issuable Upon Conversion of the 2020 Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	3,333,333
Warrants for Series AA Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	56,408	266,428
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	911,075	11,835

Accrued_Expenses_Schedule_of_A

Accrued Expenses - Schedule of Accrued Expenses (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Research and development	$18	$116
Government payable	429	421
Compensation and benefits	345	293
Professional fees	244	155
Other	16	7
Total	$1,052	$992

Debt_2020_Convertible_Notes_Ad

Debt - 2020 Convertible Notes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 24, 2015	Feb. 23, 2015
Debt Instrument [Line Items]
Debt instrument, unamortized discount	$12,333,000	$12,333,000
Accrued interest	104,000
2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			1,000,000	20,000,000
Debt instrument maturity date	15-Feb-20
Interest accrued per annum	5.00%
Financing costs incurred by the company	2,097,000
Number of shares, note gets converted into	158.7302
Principal amount	1,000
Discount rate	2.00%
Holdings in debt outstanding	25.00%
Number of days after default	180 days
Fair value of combined embedded derivative liability	10,426,000			11,850,000
Derivative liabilities and discount recorded			573,000
Change in estimated fair value of combined embedded derivative liability	1,997,000
Interest expense	209,000
Amortization of financing costs and discounts	105,000
Debt instrument, unamortized discount	12,333,000
Unamortized debt issuance expense	2,082,000
Accrued interest	$104,000
2020 Convertible Notes [Member] | First 90 Days [Member]
Debt Instrument [Line Items]
Additional interest rate	0.25%
2020 Convertible Notes [Member] | 91 to 180 Days [Member]
Debt Instrument [Line Items]
Additional interest rate	0.50%
2020 Convertible Notes [Member] | Fundamental Change [Member]
Debt Instrument [Line Items]
Percentage of principal amount of notes to be purchased	100.00%
Repurchase price description	Upon a Fundamental Change, each Holder shall have the right to require the Company to repurchase for cash all of such Holderbs notes, or any portion thereof that is equal to $1 or an integral multiple of $1.
Repurchase price	$1
2020 Convertible Notes [Member] | Fundamental Change [Member] | Maximum [Member]
Debt Instrument [Line Items]
Number of shares, note gets converted into	0
2020 Convertible Notes [Member] | Fundamental Change [Member] | Minimum [Member]
Debt Instrument [Line Items]
Number of shares, note gets converted into	7.9364

Debt_Summary_of_Issuance_of_Co

Debt - Summary of Issuance of Convertible Notes (Detail) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Carrying value	$8,667
2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Gross proceeds	21,000
Initial value of embedded derivatives	-12,423
Amortization of debt discount	90
Carrying value	$8,667

Debt_Convertible_Bridge_Notes_

Debt - Convertible Bridge Notes - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 28, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Amortization of financing costs	$44,000	$51,000
Losses on extinguishment of debt	-522,000
Convertible Bridge Notes [Member]
Debt Instrument [Line Items]
Debt instrument principal amount				2,000,000
Maturity date	30-Jun-15
Debt instrument annual interest rate	8.00%			8.00%
Debt instrument, interest expense to coupon rate	23,000
Amortization of financing costs	128,000
Losses on extinguishment of debt	-360,000
Debt converted into shares of common stock			337,932
Share offering price			$6
Gain in change in fair value	480,000
Convertible Bridge Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Gross proceeds				$40,000,000

Debt_Notes_Payable_Additional_

Debt - Notes Payable - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended
	Jun. 28, 2013	Feb. 28, 2015	Mar. 31, 2015	Mar. 31, 2014	Jan. 31, 2015	Jun. 28, 2013
			Installment			Entity
						Agreement
Debt Instrument [Line Items]
Losses on extinguishment of debt			($522,000)
Change in fair value of warrant liabilities			267,000	-193,000
Notes Payable [Member]
Debt Instrument [Line Items]
Number of loan and security agreements	2					2
Number of financial entities	2					2
Debt instrument principal balance	3,500,000					3,500,000
Proceeds from loans issued	6,915,000
Interest rate			11.00%
Debt instrument maturity date			1-Oct-16
Interest only payments for initial			12 months
Number of installments			27
Termination payment percentage		3.00%	3.00%
Loan termination payment		210,000	210,000
Warrant or right securities called by warrants, amount			350,000
Warrant expiration date			The warrants expire on the earlier of (i) ten years after the date of grant, or (ii) immediately prior to an acquisition transaction, as defined in the warrants.
Repaying principal amount		5,347,000
Prepayment fee		160,000
Interest accrued		23,000
Debt instrument, principal payments					243,000
Losses on extinguishment of debt			-482,000
Interest expense related to loan agreements			115,000	243,000
Accretion of debt discounts and termination payment			26,000	51,000
Warrants issued to lenders exercisable to common shares			56,408
Warrants issued to lenders exercisable to common shares, price per share			$6.20
Change in fair value of warrant liabilities			267,000
Reclassification of fair value of warrant liability to equity upon initial public offering			215,000
Notes Payable [Member] | Warrants [Member]
Debt Instrument [Line Items]
IPO price of the Company's common stock			$6
Fair value assumptions, expected term			8 years 4 months 24 days
Fair value assumptions, risk free interest rate			1.70%
Fair value assumptions, expected volatility rate			60.00%
Fair value of the warrant liability			$215,000
Notes Payable [Member] | Series AA Preferred Stock [Member]
Debt Instrument [Line Items]
Preferred stock issued to lenders			228,906
Preferred stock issued to lenders, price per share			$1.53

Equity_Additional_Information_

Equity - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	0 Months Ended	48 Months Ended	12 Months Ended
	Jan. 31, 2015	Nov. 30, 2014	Mar. 31, 2015	Aug. 28, 2014	Aug. 30, 2018	Dec. 31, 2014	Feb. 28, 2015
Stockholders Equity [Line Items]
Common stock, shares authorized			120,000,000			43,509,727	120,000,000
Common stock, par value			$0.01			$0.01	$0.01
Preferred stock, shares authorized						28,659,924
Preferred stock, par value			$0.00			$0.00	$0.00
Preferred stock, shares authorized			5,000,000			5,000,000	5,000,000
Reverse stock split, conversion ratio	1.197	3.39
Reverse stock split, description			In November 2014, the board of directors and the stockholders of the Company approved a 1-for-3.39 reverse stock split of the Company's outstanding common stock and in January 2015, the board of directors and the stockholders of the Company approved a 1-for-1.197 reverse stock split of the Company's outstanding common stock
Redeemable convertible preferred stock						$46,801,000
Common stock voting rights description			One vote per share
Common stock, shares outstanding			16,327,003			1,020,088
2014 Stock Option and Incentive Plan [Member]
Stockholders Equity [Line Items]
Preferred stock shares vested				59,142
Stock based compensation expense			414,000
Percentage of outstanding common stock increased to shares available for grant			13.70%
Number of shares available for grant			2,175,216
Stock options granted			0	840,975
Expiration period of stock options				10 years
Exercise price of stock options granted			$0	$4.34
Stock options, terms of vesting				These stock options will vest 25% on the one-year anniversary of the grant date and remaining 75% will vest equally over the following 35 monthly anniversaries.
Additional stock options granted				59,142
Stock options, dividend yield			0.00%
Closing price of common stock			$5.42
Stock options, intrinsic value			970,000			970,000
2014 Stock Option and Incentive Plan [Member] | General and Administrative Expense [Member]
Stockholders Equity [Line Items]
Stock based compensation expense			218,000
2014 Stock Option and Incentive Plan [Member] | Research and Development Expense [Member]
Stockholders Equity [Line Items]
Stock based compensation expense			196,000
2014 Stock Option and Incentive Plan [Member] | Vest on One-Year Anniversary [Member]
Stockholders Equity [Line Items]
Stock options, vesting percentage				25.00%
2014 Stock Option and Incentive Plan [Member] | Vest Equally Over 35 Monthly Anniversaries [Member]
Stockholders Equity [Line Items]
Stock options, vesting percentage				75.00%
2014 Stock Option and Incentive Plan [Member] | Minimum [Member]
Stockholders Equity [Line Items]
Stock options, expected term			5 years
Stock options, expected stock price volatility			83.30%
Stock options, risk free rate			1.63%
2014 Stock Option and Incentive Plan [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Stock options, expected term			6 years 3 months
Stock options, expected stock price volatility			92.50%
Stock options, risk free rate			1.84%
2004 Stock Option Plan [Member]
Stockholders Equity [Line Items]
Stock options granted			0
Exercise price of stock options granted			$0
Closing price of common stock			$5.42
Stock options, intrinsic value			0
Employee Stock Purchase Plan [Member]
Stockholders Equity [Line Items]
Percentage of outstanding common stock increased to shares available for grant			1.00%
Number of shares available for grant			160,276
Number of shares issued			0
Employee Stock Purchase Plan [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Number of shares reserved for future issuance			600,000
Scenario, Forecast [Member] | 2014 Stock Option and Incentive Plan [Member]
Stockholders Equity [Line Items]
Stock based compensation expense					2,798,000
IPO [Member]
Stockholders Equity [Line Items]
Conversion of preferred stock to common stock			8,002,650
Stock based compensation expense			950,000
Series AA Redeemable Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares authorized			0			25,757,874
Preferred stock, shares outstanding			0			24,057,013
Redeemable convertible preferred stock						46,253,000
Series AA Redeemable Convertible Preferred Stock [Member] | Conversion of Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Common stock, par value			$75
Redeemable convertible preferred stock			46,383,000
Preferred stock, additional paid in capital			46,308,000
Series X Redeemable Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares authorized			0			2,902,050
Preferred stock, shares outstanding			0			1,892,320
Redeemable convertible preferred stock						548,000
Preferred stock shares vested						558,862
Series X Redeemable Convertible Preferred Stock [Member] | Conversion of Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Common stock, par value			$5
Redeemable convertible preferred stock			548,000
Preferred stock, additional paid in capital			$543,000
Series AA and Series X Redeemable Convertible Preferred Stock [Member] | IPO [Member]
Stockholders Equity [Line Items]
Preferred stock, shares outstanding			25,949,333

Equity_Summary_of_Stock_Option

Equity - Summary of Stock Option Activity (Detail) (USD $)	0 Months Ended	3 Months Ended
	Aug. 28, 2014	Mar. 31, 2015
2014 Stock Option and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance		900,117
Number of Shares , Granted	840,975	0
Number of Shares , Exercised		0
Number of Shares , Expired		0
Number of Shares Outstanding, Ending Balance		900,117
Number of Shares, Options Exercisable		59,142
Weighted-average years remaining on contractual life		9 years 4 months 24 days
Unrecognized compensation cost related to non-vested stock options		$2,384,000
Weighted Average Exercise Price Per Share, Beginning Balance		$4.34
Weighted Average Exercise Price Per Share, Granted	$4.34	$0
Weighted Average Exercise Price Per Share, Exercised		$0
Weighted Average Exercise Price Per Share, Expired		$0
Weighted Average Exercise Price Per Share, Ending Balance		$4.34
Weighted Average Exercise Price Per Share, Options Exercisable		$4.34
Aggregate Intrinsic Value, Outstanding Beginning Balance		970,000
Aggregate Intrinsic Value, Outstanding Ending Balance		970,000
Aggregate Intrinsic Value, Options Exercisable		64,000
2004 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance		10,958
Number of Shares , Granted		0
Number of Shares , Exercised		0
Number of Shares , Expired		0
Number of Shares Outstanding, Ending Balance		10,958
Number of Shares, Options Exercisable		10,958
Weighted-average years remaining on contractual life		3 years
Weighted Average Exercise Price Per Share, Beginning Balance		$40.58
Weighted Average Exercise Price Per Share, Granted		$0
Weighted Average Exercise Price Per Share, Exercised		$0
Weighted Average Exercise Price Per Share, Expired		$0
Weighted Average Exercise Price Per Share, Ending Balance		$40.58
Weighted Average Exercise Price Per Share, Options Exercisable		$40.58
Aggregate Intrinsic Value, Outstanding Ending Balance		$0

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Operating leases, rent expenses	$15	$15
Operating leases, future payments due	$43

Fair_Value_of_Financial_Measur2

Fair Value of Financial Measurements - Fair Value of Liabilities Measured on Recurring Basis (Detail) (Fair Value Measurements, Recurring [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
2020 Convertible Notes Derivative [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure	$10,426
Convertible Preferred Stock Warrant Liability [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure		482
Convertible Bridge Notes Redemption Rights Derivative [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure		480
Level 3 [Member] | 2020 Convertible Notes Derivative [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure	10,426
Level 3 [Member] | Convertible Preferred Stock Warrant Liability [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure		482
Level 3 [Member] | Convertible Bridge Notes Redemption Rights Derivative [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure		$480

Fair_Value_of_Financial_Measur3

Fair Value of Financial Measurements - Schedule of Assumptions Used to Estimate Fair Value of Series AA Preferred Stock Warrants (Detail) (Convertible Preferred Stock Warrant Liability [Member])	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Volatility	65.00%		60.00%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Volatility		65.00%
Expected term (years)	6 months	2 months 1 day	1 year
Risk-free rate	0.06%	0.02%	0.13%
Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Volatility		70.00%
Expected term (years)	9 months	6 months	1 year 3 months
Risk-free rate	0.09%	0.03%	0.19%

Fair_Value_of_Financial_Measur4

Fair Value of Financial Measurements - Additional Information (Detail) (Convertible Bridge Notes Redemption Rights Derivative [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Convertible Bridge Notes Redemption Rights Derivative [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value inputs, probability of occurrence to change in control redemption feature	25.00%
Fair value inputs, discount rate under control redemption feature	18.90%
Fair value of embedded derivative	$480

Fair_Value_of_Financial_Measur5

Fair Value of Financial Measurements - Schedule of Change in Company's Level 3 Liabilities (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Convertible Preferred Stock Warrant Liability [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Gains and Losses [Line Items]
Beginning Balance	$482	$1,888
Change in fair value	-267	193
Reclassification to stockholders' equity	-215
Ending Balance		2,081
Convertible Bridge Notes Redemption Rights Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Gains and Losses [Line Items]
Beginning Balance	480
Change in fair value	-480
2020 Convertible Notes Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Gains and Losses [Line Items]
Issuance of 2020 Convertible Notes	12,423
Change in fair value	-1,997
Ending Balance	$10,426

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Summary of Fair Values of Derivative Instruments Not Designated as Hedging Instruments (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
2020 Convertible Notes Derivative [Member]
Derivatives, Fair Value [Line Items]
Liability derivatives at fair value	$10,426
Convertible Bridge Notes Redemption Rights Derivative [Member]
Derivatives, Fair Value [Line Items]
Liability derivatives at fair value		$480

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Effect of Derivative Instrument Not Designated as Hedging Instruments on Statement of Operations (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
Change in Fair Value of 2020 Convertible Notes Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in income on derivative	$1,997
Change in Fair Value of Convertible Bridge Notes Redemption Rights Derivative[Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in income on derivative	$480

Management_Incentive_Plan_Addi

Management Incentive Plan - Additional Information (Detail) (2014 Management Incentive Plan [Member])	1 Months Ended
	Aug. 31, 2014
Minimum [Member]
Compensation Related Costs Disclosure [Line Items]
Portion of transaction proceeds, bonus for each participants under bonus pool	7.00%
Maximum [Member]
Compensation Related Costs Disclosure [Line Items]
Portion of transaction proceeds, bonus for each participants under bonus pool	9.75%