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Derivative financial instruments not

designated as hedging instruments

Location of gain or loss

recognized in income

on derivative

financial instrument

Amount of gain or (loss)
recognized in income on
derivative financial
instrument

2020 Convertible Notes derivative liability

Change in fair value of 2020 Convertible Notes derivative liability

Convertible Bridge Notes

Change in fair value of Convertible Bridge Notes redemption rights derivative

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2016	May 10, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q1
Trading Symbol	ITEK
Entity Registrant Name	Inotek Pharmaceuticals Corporation
Entity Central Index Key	0001281895
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		26,423,394

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 58,706	$ 80,042
Short-term investments	43,559	31,238
Prepaid expenses and other current assets	982	1,086
Total current assets	103,247	112,366
Property and equipment, net	790	812
Other assets	170	143
Total assets	104,207	113,321
Current liabilities:
Accounts payable	1,376	1,633
Accrued expenses and other current liabilities	3,238	2,508
Total current liabilities	4,614	4,141
Other long-term liabilities	351	367
Total liabilities	4,965	4,508
Commitments and Contingencies (Note 7)
Stockholders' equity:
Preferred Stock, $0.001 par value: 5,000,000 shares authorized and no shares issued or outstanding
Common stock, $0.01 par value: 120,000,000 shares authorized; 26,423,394 shares issued and outstanding at March 31, 2016 and December 31, 2015	264	264
Additional paid-in capital	305,069	304,583
Accumulated deficit	(206,091)	(196,023)
Accumulated other comprehensive loss		(11)
Total stockholders' equity	99,242	108,813
Total liabilities and stockholders' equity	$ 104,207	$ 113,321

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
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	120,000,000
Common stock, shares issued	26,423,394	26,423,394
Common stock, shares outstanding	26,423,394	26,423,394

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating expenses:
Research and development	$ (7,615)	$ (1,069)
General and administrative	(2,522)	(1,980)
Loss from operations	(10,137)	(3,049)
Interest expense		(474)
Interest income	69
Loss on extinguishment of debt		(683)
Change in fair value of warrant liabilities		267
Change in fair value of Convertible Bridge Notes redemption rights derivative		480
Change in fair value of 2020 Convertible Notes derivative liability		1,997
Net loss	$ (10,068)	$ (1,462)
Net loss per share attributable to common stockholders-basic and diluted	$ (0.38)	$ (0.21)
Weighted-average number of shares outstanding-basic and diluted	26,423,394	7,677,575

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (10,068)	$ (1,462)
Other comprehensive income:
Net unrealized gain on marketable securities	11
Total comprehensive loss	$ (10,057)	$ (1,462)

- Definition

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

+ References + Details

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (10,068)	$ (1,462)
Adjustments to reconcile net loss to cash used in operating activities:
Noncash interest expense		274
Deferred rent and lease incentives	(16)
Loss on extinguishment of debt		522
Amortization of premium on marketable securities	43
Depreciation	37	0
Change in fair value of warrant liabilities		(267)
Change in fair value of Convertible Bridge Notes redemption rights derivative		(480)
Change in fair value of 2020 Convertible Notes derivative liability		(1,997)
Stock-based compensation	486	1,364
Changes in operating assets and liabilities:
Prepaid expenses and other assets	52	(271)
Accounts payable	(257)	154
Accrued expenses and other current liabilities	730	170
Net cash used in operating activities	(8,993)	(1,993)
Cash flows from investing activities:
Purchases of short-term investments	(24,161)
Proceeds from the maturities of short-term investments	11,833
Purchases of property and equipment	(15)
Net cash used in investing activities	(12,343)
Cash flows from financing activities:
Net proceeds from issuance of common stock in initial public offering		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 payments on notes payable		(5,800)
Net cash provided by financing activities		51,514
Net change in cash and cash equivalents	(21,336)	49,521
Cash and cash equivalents, beginning of period	80,042	3,618
Cash and cash equivalents, end of period	58,706	53,139
Supplemental disclosure of cash flow information:
Cash paid for interest		89
Supplemental disclosure of noncash investing and financing activities:
Net unrealized gain on marketable securities	$ 11
IPO [Member]
Supplemental disclosure of noncash investing and financing activities:
Conversion of Notes into common stock		2,028
Reclassification of fair value of warrant liability to equity upon initial public offering		215
Reclassification of deferred public offering costs to stockholders' 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:
Accretion of Series AA preferred stock to redemption value		130
Series AA Redeemable Convertible Preferred Stock [Member] \| IPO [Member]
Supplemental disclosure of noncash investing and financing activities:
Conversion of 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 preferred stock into common stock upon initial public offering		$ 548

Organization and Operations	3 Months Ended
Organization and Operations	Mar. 31, 2016
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 are 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 protect proprietary technology and to the dependence on key individuals. In the first quarter of 2015, the Company completed its initial public offering (the “IPO”) of (i) 6,966,333 shares of common stock, including 299,333 shares from an exercise of the underwriters’ overallotment option at a price of $6.00 per share and (ii) $21,000 aggregate principal amount of 5.0% Convertible Senior Notes due 2020 (the “2020 Convertible Notes”), including $1,000 from an exercise of the underwriters’ overallotment option. Existing stockholders and their affiliated entities purchased approximately 3,005,000 shares of common stock issued in the IPO at the same terms. The Company received net proceeds of $36,495, 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. In July and August 2015, holders of $21,000 principal amount of the 2020 Convertible Notes elected to convert the principal into 3,333,319 shares of common stock. In addition, the Interest Make-Whole Payment (see Note 5) was settled with shares of common stock, at the election of the Company, resulting in the issuance of 530,072 additional shares of common stock. In August 2015, the Company completed an underwritten public offering of its common stock (the “Follow-on Offering”). The Company issued 6,210,000 shares of its common stock at a price of $12.75 per share, including 810,000 shares from the underwriters’ full exercise of their overallotment option, and received net proceeds of $73,965, after deducting underwriting discounts and offering-related costs. As of March 31, 2016, the Company had an accumulated deficit of $206,091 and $102,265 of cash and cash equivalents and short-term investments. 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 the Company’s 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 Policies

3 Months Ended

Mar. 31, 2016

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, 2015 included in the Company’s Annual Report on Form 10-K. The results for the three months ended March 31, 2016 are not necessarily indicative of the results to be expected for a full year, any other interim periods or any future year or period.

Segment Reporting—Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment.

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.

Comprehensive income (loss) —Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions, and other events and circumstances from non-owner sources, and currently consists of net loss and changes in unrealized gains and losses on short-term investments. Accumulated other comprehensive income (loss) consists entirely of unrealized gains and losses from short-term investments as of March 31, 2016 and December 31, 2015.

Cash and Cash Equivalents—Cash and cash equivalents consist of bank deposits, certificates of deposit 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.

Short-term Investments—Short-term investments consist of investments in certificates of deposit, agency bonds and United States Treasury securities. Management determines the appropriate classification of these securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its short-term investments as available-for-sale pursuant to Financial Accounting Standards Board (“FASB”) Accounting Standard Codification (“ASC”) 320, Investments—Debt and Equity Securities. Short-term investments are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive income (loss) in stockholders’ equity and a component of total comprehensive loss in the consolidated statements of comprehensive loss, until realized. Realized gains and losses are included in investment income on a specific-identification basis. There were no realized gains or losses on short-term investments for the three months ended March 31, 2016 and 2015. There was $11 of net unrealized gains on short-term investments for the three months ended March 31, 2016. There were no net unrealized gains or losses on short-term investments for the three months ended March 31, 2015.

The Company reviews short-term investments for other-than-temporary impairment whenever the fair value of a short-term investment is less than the amortized cost and evidence indicates that a short-term investment’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statements of operations if the Company has experienced a credit loss, has the intent to sell the short-term investment, or if it is more likely than not that the Company will be required to sell the short-term investment before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.

Short-term investments at March 31, 2016 consist of the following:


	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Certificates of deposit	$	17,932	$	—	$	—		$	17,932
Agency bonds		5,502		1		(1	)		5,502
United States Treasury securities		20,125		2		(2	)		20,125

	$	43,559	$	3	$	(3	)	$	43,559

Short-term investments at December 31, 2015 consist of the following:


	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Certificates of deposit	$	16,160	$	—	$	—		$	16,160
Agency bonds		10,036		—		(5	)		10,031
United States Treasury securities		5,053		—		(6	)		5,047

	$	31,249	$	—	$	(11	)	$	31,238

At March 31, 2016 and December 31, 2015, all short-term investments held by the Company had contractual maturities of less than one year. The Company evaluated its securities for other-than-temporary impairment and determined that no such impairment existed at March 31, 2016 and December 31, 2015.

Property and Equipment—Property and equipment are stated at cost. Expenditures for repairs and maintenance are charged to expense as incurred. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is reflected in the consolidated statement of operations. Depreciation and amortization is provided using the straight-line method over the estimated useful lives of the assets.

Deferred Public Offering Costs— Deferred public offering costs consist primarily of direct, incremental legal, accounting, Securities and Exchange Commission and NASDAQ Global Market fees. At March 31, 2016, the Company had $182 of deferred public offering costs related to shares expected to be issued pursuant to the Form S-3 Registration Statement filed by the Company on April 4, 2016 (see Note 10), capitalized as a component of prepaid expenses and other current assets in the accompanying consolidated balance sheets as of March 31, 2016. There were no deferred public offering costs recorded as of December 31, 2015.

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 amortized over the term of the respective notes using the effective interest rate method. At March 31, 2016 and December 31, 2015, the Company no longer carried the notes payable, Convertible Bridge Notes or 2020 Convertible Notes on its balance sheet (see Note 5). Amortization of deferred financing costs was $44 in the three months ended March 31, 2015, and recorded as a component of interest expense in the accompanying consolidated statements of operations.

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. Compensation cost for stock purchase rights under the employee stock purchase plan is measured and recognized on the date the Company becomes obligated to issue shares of our common stock and is based on the difference between the fair value of the Company’s common stock and the purchase price on such date.

The Company accounts for stock options issued to non-employees in accordance with the provisions of the FASB 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. FASB 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 liability (see Note 8).

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 8 and 9).

Net Loss Per Share—The Company calculates net loss per share in accordance with FASB 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,
	2016			2015
Numerator:
Net loss	$	(10,068	)	$	(1,462	)
Accretion and dividends on convertible preferred stock		—			(130	)

Net loss applicable to common stockholders		(10,068	)		(1,592	)
Denominator:
Weighted average common shares outstanding - basic and diluted		26,423,394			7,677,575

Net loss per share applicable to common stockholders - basic and diluted	$	(0.38	)	$	(0.21	)

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,
	2016		2015
Shares issuable upon conversion of the 2020 Convertible Notes		—		3,333,333
Warrants for common stock		56,408		56,408
Stock options		2,400,177		911,075

Total		2,456,585		4,300,816

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 (see Note 10).

Recent Accounting Pronouncements—In August 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-15, Presentation of Financial Statements – Going Concern, which provides guidance about management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. The new standard is effective for the Company for the annual period ending after December 15, 2016, and for annual and interim periods thereafter, with early adoption permitted. The Company is currently evaluating the impact of this accounting standard update on the Company’s consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which supersedes the current leasing guidance and upon adoption, will require lessees to recognize right-of-use assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. The new standard is effective for the Company for the annual period beginning after December 15, 2018, and can be early adopted by applying a modified retrospective approach for leases existing at, and entered into after, the beginning of the earliest comparable period presented in the financial statements. The Company is currently evaluating the impact of this accounting standard update on the Company’s consolidated financial statements.

In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting, which amends ASC Topic 718, Compensation – Stock Compensation, and includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. The new standard is effective for the Company for the annual period ending after December 15, 2016, and for annual and interim periods thereafter, with early adoption permitted. The Company is currently evaluating the impact of this accounting standard update on the Company’s consolidated financial statements.

Property and Equipment

3 Months Ended

Mar. 31, 2016

Property, Plant and Equipment [Abstract]

Property and Equipment

3. Property and Equipment

At March 31, 2016 and December 31, 2015, the Company’s property and equipment consisted of the following:


	Useful lives	March 31, 2016			December 31, 2015
Office equipment	5 years	$	349		$	334
Computer hardware and software	3 - 7 years		252			252
Laboratory equipment	5 years		43			43
Leasehold improvements	7 years		445			445

			1,089			1,074
Less: accumulated depreciation			(299	)		(262	)

Property and equipment, net		$	790		$	812

During the three months ended March 31, 2016 and 2015, the Company recognized $37 and $0 of depreciation expense, respectively.

Accrued Expenses and Other Current Liabilities

3 Months Ended

Mar. 31, 2016

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

4. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities at March 31, 2016 and December 31, 2015 consisted of the following:


	March 31, 2016		December 31, 2015
Research and development	$	1,394	$	375
Government payable		457		450
Compensation and benefits		590		999
Professional fees		523		347
Other		274		337

Total	$	3,238	$	2,508

Debt	3 Months Ended
Debt	Mar. 31, 2016
Debt Disclosure [Abstract]
Debt	5. 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 had a maturity date of February 15, 2020 (“Maturity Date”), were unsecured and accrued 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. Each holder of a 2020 Convertible Note (the “Holder”), had 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 was 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 occurred on or after July 23, 2015, the Company would, in addition to the other consideration payable, make an interest make-whole payment (the “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 2020 Convertible 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 2020 Convertible Notes had not been so converted or otherwise repurchased. Present values for the Interest Make-Whole Payment would be calculated using a discount rate equal to 2%. The Company could 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 were convertible, at the holder’s option, upon a fundamental change (“Fundamental Change”), as defined in the Indenture (“Indenture”). If a holder elected to convert its notes upon a Fundamental Change, the Company would increase the Conversion Rate for the 2020 Convertible Notes so surrendered for conversion by a number of additional shares of common stock by which the Conversion Rate would have 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 ranged from 7.9364 to 0. Upon a Fundamental Change, each Holder would 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 2020 Convertible Notes would equal 100% of the principal amount thereof, plus accrued and unpaid interest thereon. However, if the repurchase occurred after a regular record date for an interest payment, but before the distribution date of that interest payment, the Holder receive the regular interest payment and the repurchase price would equal 100% of the principal amount of the 2020 Convertible Notes to be repurchased. The 2020 Convertible Notes were redeemable 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) occurred and was 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, could declare 100% of the principal and accrued and unpaid interest, if any, on all of the 2020 Convertible 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 2020 Convertible Notes would become due and payable automatically. The Indenture provided that, to the extent the Company elected 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, consisted exclusively of the right to receive additional interest (“Additional Interest”) on the 2020 Convertible Notes. The Additional Interest consisted 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 would consist of interest at an additional rate of 0.50% per annum. After 180 days, if the Event of Default was not cured or waived, the 2020 Convertible Notes were subject to acceleration as provided in Section 6.02 of the Indenture. The Company determined that the conversion option, Interest Make-Whole Payments and the Additional Interest were embedded derivatives that required bifurcation and separate accounting under FASB 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 2020 Convertible Notes, the Company estimated the fair value of the conversion option including the interest make-whole provision and the Additional Interest using the “with” and “without” method. Using this methodology, the Company first valued the 2020 Convertible Notes with the conversion option including make-whole provision but excluding the Additional Interest (the “with” scenario) and subsequently valued the 2020 Convertible 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 2020 Convertible 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. The Company developed an estimate of fair value for the 2020 Convertible Notes excluding the Additional Interest using a binomial lattice model. The Company 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 2020 Convertible Notes were convertible and choosing the action that would maximize the return to the 2020 Convertible Notes’ holders. The significant assumptions used in the binomial model were: the market yield and the expected volatility. The Company 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 2020 Convertible 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 and the debt discount were recorded in other assets and were 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 were recorded in earnings in the period in which the changes occurred. 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. In July and August 2015, holders of all $21,000 principal amount of the 2020 Convertible Notes elected to convert the principal into 3,333,319 shares of common stock in accordance with the terms of the 2020 Convertible Notes. In addition, the Interest Make-Whole Payment was settled with shares of common stock, at the election of the Company, resulting in the issuance of 530,072 additional shares of common stock. As of December 31, 2015, all $21,000 of the 2020 Convertible Notes were extinguished. Interest expense related to the 2020 Convertible Notes for the three months ended March 31, 2015, was $209, including $15 related to amortization of the issuance costs and $90 related to amortization of the debt discount. *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 were scheduled to mature on June 30, 2015 and accrued interest at the rate of 8% per annum and were 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 would 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 per share. 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 bore interest at a rate per annum of 11.0%. The Loans would 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 would be 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. 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 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 number of shares of common stock and qualified for equity classification under the accounting guidance, and the fair value of the $215 was reclassified to additional paid-in capital as of the IPO date.

Equity

3 Months Ended

Mar. 31, 2016

Equity [Abstract]

Equity

6. Equity

Authorized Shares

As of March 31, 2016, the Company’s authorized capital stock consisted 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.

Preferred Stock

During 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 upon completion of the IPO 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 Company’s board of directors. At March 31, 2016 and December 31, 2015, there were 26,423,394 shares common stock outstanding.

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. Pursuant to the provisions of the 2014 Plan and approval by the board of directors, on January 1, 2016 an additional 1,056,936 shares were added to the 2014 Plan representing 4% of total common shares issued and outstanding at December 31, 2015. There were 833,035 shares issuable under the 2014 Plan as of March 31, 2016. The 2014 Plan expires in August 2024.

In the three months ended March 31, 2016, the Company recorded aggregate stock-based compensation expense of $466 for stock options under the 2014 Plan: $269 in general and administrative expense and $197 in research and development expense. In the three months ended March 31, 2015, the Company recorded an aggregate stock-based compensation expense of $414 for stock options under the 2014 Plan: $218 in general and administrative expense and $196 in research and development expense.

During the three months ended March 31, 2016, the board of directors granted a total of 796,500 ten-year term stock options to employees of the Company. 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 5.97 to 6.08 years; expected stock price volatility of 77.5% to 77.7%, a risk free rate of 1.47% to 1.90%, and a dividend yield of 0%. The Company will recognize $4,080 of stock-based compensation expense for these stock options on a straight-line basis commencing upon the grant dates through the final vesting dates.

The following table summarizes activity for the three months ended March 31, 2016 under the 2014 Plan:


	Number of Shares			Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value
Options outstanding at December 31, 2015		1,620,760		$	4.95	$	10,339
Granted		796,500		$	7.80	$	—
Exercised		—		$	—	$	—
Cancelled		(28,000	)	$	6.79	$	—

Options outstanding at March 31, 2016		2,389,260		$	5.87	$	4,164

Options exercisable at March 31, 2016		515,942		$	4.52	$	1,485

Weighted-average years remaining on contractual life		9.19
Unrecognized compensation cost related to non-vested stock options	$	8,200

The weighted-average fair value of all stock options granted for the three months ended March 31, 2016 was $5.25 per share. Aggregate intrinsic value is based on $7.40 per share, the closing price of common stock on March 31, 2016.

2004 Stock Option and Incentive Plan

The Company has outstanding stock options pursuant to its 2004 Stock Option and Incentive Plan (the “2004 Plan”). The 2004 Plan has expired but remains effective for all outstanding options under the 2004 Plan. The following table summarizes activity for the three months ended March 31, 2016 under the 2004 Plan:


	Number of Shares		Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value
Options outstanding at December 31, 2015		10,917	$	40.58	$	—
Granted		—	$	—	$	—
Exercised		—	$	—	$	—
Expired		—	$	—	$	—

Options outstanding at March 31, 2016		10,917	$	40.58	$	—

Options exercisable at March 31, 2016		10,917	$	40.58	$	—

Weighted-average years remaining on contractual life		2.03
Unrecognized compensation cost related to non-vested stock options	$	—

The exercise prices exceed the $7.40 per share closing price of common stock on March 31, 2016, 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 (“ESPP”). 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 January 1, 2016, 117,100 shares were added to the ESPP. As of March 31, 2016, there were 264,233 shares available for issuance under the ESPP.

As of March 31, 2016, there was $46 withheld from employees that will be used to purchase shares of the Company’s common stock on May 31, 2016, which is the last day of the current offering period. The Company recorded $20 of stock-based compensation expense pursuant to the ESPP during the three months ended March 31, 2016.

- Definition

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

+ References

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-Subparagraph (SX 210.4-08.(d),(e))
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-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Commitments and Contingencies

3 Months Ended

Mar. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. Commitments and Contingencies

Operating leases

In May 2015, the Company entered into a lease agreement (the “Office Lease”) for its headquarters in Lexington, Massachusetts. The Company occupied this space in September 2015, at which time its rental obligations commenced. The Company recorded $445 as leasehold improvements for costs incurred to build out the space, and is amortizing those costs to facilities expense over the term of the lease. Rent expense is recognized on a straight-line basis at the average monthly rent over the term of the lease. Deferred rent is included in other current and long-term liabilities on the Company’s consolidated balance sheets. Rent expense related to the Office Lease was $62 for the three months ended March 31, 2016. Rent expense was $15 for the three months ended March 31, 2015, and was related to the Company’s prior lease agreement which expired in September 2015.

In February 2016, the Company signed an amendment to the Office Lease, whereby it agreed to rent additional space (the “Lease Amendment”). The Company expects to occupy the additional space in July 2016. The terms of the Lease Amendment follow the terms of the Office Lease. If occupancy occurs on July 1, 2016, the aggregate annual commitments pursuant to the Office Lease and the Lease Amendment are as follows:


Year	Amount
2016	$	177
2017		402
2018		411
2019		421
2020		430
Thereafter		959

Total	$	2,800

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.

Derivative Financial Instruments

3 Months Ended

Mar. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

9. 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. 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:

See Notes 5 and 8 for additional discussion regarding the accounting for and valuation of these derivative financial instruments.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

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+ Details

Subsequent Event	3 Months Ended
Subsequent Event	Mar. 31, 2016
Subsequent Events [Abstract]
Subsequent Event	10. Subsequent Event In April 2016, the Company filed a registration statement on Form S-3 containing two prospectuses: (i) a base prospectus which covers the offering, issuance and sale of up to $200,000 in the aggregate of an indeterminate number of shares of common stock and preferred stock, such indeterminate principal amount of debt securities and such indeterminate number of warrants and units; and (ii) a sales agreement prospectus covering the offering, issuance and sale of up to a maximum aggregate offering price of $50,000 of the Company’s common stock that may be issued and sold under a sales agreement with Cowen and Company, LLC. The sales agreement prospectus amount of $50,000 is included in the base prospectus amount of $200,000.

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2016

Accounting Policies [Abstract]

Basis of Presentation

Segment Reporting

Use of Estimates

Comprehensive income (loss)

Cash and Cash Equivalents

Short-term Investments

Short-term investments at March 31, 2016 consist of the following:


	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Current:
Certificates of deposit	$	17,932	$	—	$	—		$	17,932
Agency bonds		5,502		1		(1	)		5,502
United States Treasury securities		20,125		2		(2	)		20,125

	$	43,559	$	3	$	(3	)	$	43,559

Short-term investments at December 31, 2015 consist of the following:


	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
Current:
Certificates of deposit	$	16,160	$	—	$	—		$	16,160
Agency bonds		10,036		—		(5	)		10,031
United States Treasury securities		5,053		—		(6	)		5,047

	$	31,249	$	—	$	(11	)	$	31,238

Property and Equipment

Deferred Public Offering Costs

Deferred Financing Costs

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.

Stock-Based Compensation

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. FASB 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.

Derivative Financial Instruments

Net 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,
	2016			2015
Numerator:
Net loss	$	(10,068	)	$	(1,462	)
Accretion and dividends on convertible preferred stock		—			(130	)

Net loss applicable to common stockholders		(10,068	)		(1,592	)
Denominator:
Weighted average common shares outstanding - basic and diluted		26,423,394			7,677,575

Net loss per share applicable to common stockholders - basic and diluted	$	(0.38	)	$	(0.21	)

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,
	2016		2015
Shares issuable upon conversion of the 2020 Convertible Notes		—		3,333,333
Warrants for common stock		56,408		56,408
Stock options		2,400,177		911,075

Total		2,456,585		4,300,816

Subsequent Events

Recent Accounting Pronouncements

Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2016

Accounting Policies [Abstract]

Schedule of Short-term Investment

Short-term investments at March 31, 2016 consist of the following:


	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Certificates of deposit	$	17,932	$	—	$	—		$	17,932
Agency bonds		5,502		1		(1	)		5,502
United States Treasury securities		20,125		2		(2	)		20,125

	$	43,559	$	3	$	(3	)	$	43,559

Short-term investments at December 31, 2015 consist of the following:


	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Certificates of deposit	$	16,160	$	—	$	—		$	16,160
Agency bonds		10,036		—		(5	)		10,031
United States Treasury securities		5,053		—		(6	)		5,047

	$	31,249	$	—	$	(11	)	$	31,238

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,
	2016			2015
Numerator:
Net loss	$	(10,068	)	$	(1,462	)
Accretion and dividends on convertible preferred stock		—			(130	)

Net loss applicable to common stockholders		(10,068	)		(1,592	)
Denominator:
Weighted average common shares outstanding - basic and diluted		26,423,394			7,677,575

Net loss per share applicable to common stockholders - basic and diluted	$	(0.38	)	$	(0.21	)

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,
	2016		2015
Shares issuable upon conversion of the 2020 Convertible Notes		—		3,333,333
Warrants for common stock		56,408		56,408
Stock options		2,400,177		911,075

Total		2,456,585		4,300,816

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Property and Equipment (Tables)

3 Months Ended

Mar. 31, 2016

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

At March 31, 2016 and December 31, 2015, the Company’s property and equipment consisted of the following:


	Useful lives	March 31, 2016			December 31, 2015
Office equipment	5 years	$	349		$	334
Computer hardware and software	3 - 7 years		252			252
Laboratory equipment	5 years		43			43
Leasehold improvements	7 years		445			445

			1,089			1,074
Less: accumulated depreciation			(299	)		(262	)

Property and equipment, net		$	790		$	812

Accrued Expenses and Other Current Liabilities (Tables)

3 Months Ended

Mar. 31, 2016

Payables and Accruals [Abstract]

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities at March 31, 2016 and December 31, 2015 consisted of the following:


	March 31, 2016		December 31, 2015
Research and development	$	1,394	$	375
Government payable		457		450
Compensation and benefits		590		999
Professional fees		523		347
Other		274		337

Total	$	3,238	$	2,508

Equity (Tables)

3 Months Ended

Mar. 31, 2016

Equity [Abstract]

Summary of Stock Option Activity

The following table summarizes activity for the three months ended March 31, 2016 under the 2014 Plan:


	Number of Shares			Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value
Options outstanding at December 31, 2015		1,620,760		$	4.95	$	10,339
Granted		796,500		$	7.80	$	—
Exercised		—		$	—	$	—
Cancelled		(28,000	)	$	6.79	$	—

Options outstanding at March 31, 2016		2,389,260		$	5.87	$	4,164

Options exercisable at March 31, 2016		515,942		$	4.52	$	1,485

Weighted-average years remaining on contractual life		9.19
Unrecognized compensation cost related to non-vested stock options	$	8,200

Aggregate intrinsic value is based on $7.40 per share, the closing price of common stock on March 31, 2016.

The following table summarizes activity for the three months ended March 31, 2016 under the 2004 Plan:


	Number of Shares		Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value
Options outstanding at December 31, 2015		10,917	$	40.58	$	—
Granted		—	$	—	$	—
Exercised		—	$	—	$	—
Expired		—	$	—	$	—

Options outstanding at March 31, 2016		10,917	$	40.58	$	—

Options exercisable at March 31, 2016		10,917	$	40.58	$	—

Weighted-average years remaining on contractual life		2.03
Unrecognized compensation cost related to non-vested stock options	$	—

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Schedule of Aggregate Annual Commitments Pursuant to Office Lease and Lease Amendment

If occupancy occurs on July 1, 2016, the aggregate annual commitments pursuant to the Office Lease and the Lease Amendment are as follows:


Year	Amount
2016	$	177
2017		402
2018		411
2019		421
2020		430
Thereafter		959

Total	$	2,800

Fair Value of Assets and Liabilities Measured on Recurring Basis (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value of Assets and 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
	March 31, 2016
	Total		Level 1		Level 2		Level 3
Assets:
Certificates of deposit	$	17,932	$	—	$	17,932	$	—
Agency bonds		5,502		—		5,502		—
United States Treasury securities		20,125		20,125		—		—

Short-term investments	$	43,559	$	20,125	$	23,434	$	—


	Fair Value Measurements at
	December 31, 2015
	Total		Level 1		Level 2		Level 3
Assets:
Certificates of deposit	$	16,160	$	—	$	16,160	$	—
Agency bonds		10,031		—		10,031		—
United States Treasury securities		5,047		5,047		—		—

Short-term investments	$	31,238	$	5,047	$	26,191	$	—

Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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:

Organization and Operations - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended
	Aug. 31, 2015	Jul. 31, 2015	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 24, 2015	Feb. 23, 2015	Jun. 28, 2013
Schedule Of Description Of Business [Line Items]
Net proceeds from issuance of equity	$ 73,965,000		$ 36,495,000
Net proceeds from issuance of debts			$ 18,903,000
Accumulated deficit				$ (206,091,000)	$ (196,023,000)
Aggregate cash and cash equivalents and marketable securities				$ 102,265,000
2020 Convertible Notes [Member]
Schedule Of Description Of Business [Line Items]
Convertible senior notes, interest rate, stated percentage				5.00%
Aggregate principal amount	$ 21,000,000	$ 21,000,000				$ 1,000,000	$ 20,000,000
Convertible Notes converted into shares	3,333,319	3,333,319
Additional shares of common stock	530,072	530,072
Senior Notes [Member] \| 2020 Convertible Notes [Member]
Schedule Of Description Of Business [Line Items]
Convertible senior notes, interest rate, stated percentage			5.00%
Aggregate principal amount			$ 21,000,000
Notes Payable [Member]
Schedule Of Description Of Business [Line Items]
Aggregate principal amount	$ 21,000,000	$ 21,000,000						$ 3,500,000
Convertible Notes converted into shares	3,333,319	3,333,319
Additional shares of common stock	530,072	530,072
IPO [Member]
Schedule Of Description Of Business [Line Items]
Initial public offering common stock, shares			6,966,333
IPO [Member] \| Affiliated Entity [Member]
Schedule Of Description Of Business [Line Items]
Initial public offering common stock, shares			3,005,000
Over-Allotment Option [Member]
Schedule Of Description Of Business [Line Items]
Initial public offering common stock, shares	810,000		299,333
Initial public offering common stock, per shares			$ 6.00
Aggregate principal amount			$ 1,000,000
Secondary Public Offering [Member]
Schedule Of Description Of Business [Line Items]
Initial public offering common stock, shares	6,210,000
Initial public offering common stock, per shares	$ 12.75

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016 USD ($) Segment	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Accounting Policies [Abstract]
Number of operating segments \| Segment	1
Realized gains or losses on short-term investment	$ 0	$ 0
Unrealized gains (losses) on short-term investment	11,000	0
Other than temporary impairment evaluated	0		$ 0
Deferred public offering costs	$ 182,000		$ 0
Amortization of deferred financing costs		$ 44,000

Significant Accounting Policies - Schedule of Short-term Investment (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Cost Basis	$ 43,559	$ 31,249
Available-for-sale securities, Unrealized Gains	3
Available-for-sale securities, Unrealized Losses	(3)	(11)
Available-for-sale securities, Fair Value	43,559	31,238
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Cost Basis	17,932	16,160
Available-for-sale securities, Fair Value	17,932	16,160
Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Cost Basis	5,502	10,036
Available-for-sale securities, Unrealized Gains	1
Available-for-sale securities, Unrealized Losses	(1)	(5)
Available-for-sale securities, Fair Value	5,502	10,031
United States Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Cost Basis	20,125	5,053
Available-for-sale securities, Unrealized Gains	2
Available-for-sale securities, Unrealized Losses	(2)	(6)
Available-for-sale securities, Fair Value	$ 20,125	$ 5,047

Significant Accounting Policies - Schedule of Computation of Basic and Diluted Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator:
Net loss	$ (10,068)	$ (1,462)
Accretion and dividends on convertible preferred stock		(130)
Net loss applicable to common stockholders	$ (10,068)	$ (1,592)
Denominator:
Weighted average common shares outstanding - basic and diluted	26,423,394	7,677,575
Net loss per share applicable to common stockholders - basic and diluted	$ (0.38)	$ (0.21)

- Definition

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

+ References + Details

Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,456,585	4,300,816
Shares 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 Exercisable for Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	56,408	56,408
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,400,177	911,075

Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 1,089	$ 1,074
Less: accumulated depreciation	(299)	(262)
Property and equipment, net	$ 790	812
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	5 years
Property and equipment, Gross	$ 349	334
Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 252	252
Computer Hardware and Software [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	3 years
Computer Hardware and Software [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	7 years
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	5 years
Property and equipment, Gross	$ 43	43
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	7 years
Property and equipment, Gross	$ 445	$ 445

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Property, Plant and Equipment, Net [Abstract]
Depreciation expense	$ 37	$ 0

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Research and development	$ 1,394	$ 375
Government payable	457	450
Compensation and benefits	590	999
Professional fees	523	347
Other	274	337
Total	$ 3,238	$ 2,508

Debt - 2020 Convertible Notes - Additional Information (Detail)	1 Months Ended		3 Months Ended		12 Months Ended
	Aug. 31, 2015 USD ($) shares	Jul. 31, 2015 USD ($) shares	Mar. 31, 2016 USD ($) $ / shares	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Mar. 24, 2015 USD ($)	Feb. 23, 2015 USD ($)
Debt Instrument [Line Items]
Interest expense				$ 474,000
2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument principal amount	$ 21,000,000	$ 21,000,000				$ 1,000,000	$ 20,000,000
Debt instrument maturity date			Feb. 15, 2020
Convertible notes, interest rate, stated percentage			5.00%
Financing costs incurred by the company			$ 2,097,000
Number of shares, note gets converted into			158.7302
Principal amount			$ 1
Discount rate			2.00%
Holdings in debt outstanding			25.00%
Number of days after default			180 days
Fair value of combined embedded derivative liability							$ 11,850,000
Derivative liabilities and discount recorded						$ 573,000
Change in estimated fair value of combined embedded derivative liability				$ 1,997,000
Convertible Notes converted into shares \| shares	3,333,319	3,333,319
Additional shares of common stock \| shares	530,072	530,072
Extinguishment of debt					$ 21,000,000
Interest expense			$ 209,000
Amortization of financing costs and discounts			15,000
Amortization of debt discount			$ 90,000
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 would 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.
Repurchase price \| $ / shares			$ 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 - Convertible Bridge Notes - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended
	Feb. 28, 2015	Dec. 31, 2014	Mar. 31, 2016	Mar. 31, 2015
Debt Instrument [Line Items]
Amortization of financing costs				$ 44,000
Losses on extinguishment of debt				$ (522,000)
2014 Convertible Bridge Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 2,000,000
Debt instrument maturity date			Jun. 30, 2015
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	$ 6.00
Gain in change in fair value				$ 480,000
2014 Convertible Bridge Notes [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Gross proceeds		$ 40,000,000

Debt - Notes Payable - Additional Information (Detail)		1 Months Ended	3 Months Ended
Debt - Notes Payable - Additional Information (Detail)	Jun. 28, 2013 USD ($) Agreement Entity	Feb. 28, 2015 USD ($)	Mar. 31, 2016 USD ($) Installment $ / shares shares	Mar. 31, 2015 USD ($)	Aug. 31, 2015 USD ($)	Jul. 31, 2015 USD ($)	Jan. 31, 2015 USD ($)
Debt Instrument [Line Items]
Losses on extinguishment of debt				$ (522,000)
Change in fair value of warrant liabilities				(267,000)
Notes Payable [Member]
Debt Instrument [Line Items]
Number of loan and security agreements \| Agreement	2
Number of financial entities \| Entity	2
Debt instrument principal balance	$ 3,500,000				$ 21,000,000	$ 21,000,000
Proceeds from loans issued	$ 6,915,000
Interest rate			11.00%
Loan maturity date			Oct. 01, 2016
Interest only payments for initial			12 months
Number of installments \| Installment			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
Interest expense related to loan agreements				115,000
Accretion of debt discounts and loan termination payment				26,000
Losses on extinguishment of debt				(322,000)
Warrants issued to lenders exercisable to common shares \| shares			56,408
Warrants issued to lenders exercisable to common shares, price per share \| $ / shares			$ 6.204
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 Exercisable for Common Stock [Member]
Debt Instrument [Line Items]
IPO price of the Company's common stock \| $ / shares			$ 6.00
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 \| shares			228,906
Preferred stock issued to lenders, price per share \| $ / shares			$ 1.529

Equity - Additional Information (Detail) - USD ($)		3 Months Ended		12 Months Ended
Equity - Additional Information (Detail) - USD ($)	Mar. 31, 2016	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Jan. 01, 2016
Stockholders Equity [Line Items]
Common stock, shares authorized	120,000,000	120,000,000		120,000,000
Common stock, par value	$ 0.01	$ 0.01		$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000		5,000,000
Preferred stock, par value	$ 0.001	$ 0.001		$ 0.001
Stock-based compensation expense			$ 950,000
Common stock voting rights description		One vote per share
Common stock, shares outstanding	26,423,394	26,423,394		26,423,394
Common Stock [Member]
Stockholders Equity [Line Items]
Amount withheld from employees	$ 46,000
2014 Stock Option and Incentive Plan [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense		$ 466,000	414,000
Number of shares reserved for future issuance	833,035	833,035				1,056,936
Percentage of outstanding common stock increased to shares available for grant				4.00%
Stock options, dividend yield		0.00%
Stock options granted		796,500
Expiration period of stock options		10 years
Stock options, intrinsic value	$ 4,164,000	$ 4,164,000		$ 10,339,000
Weighted-average fair value of stock options granted		$ 5.25
2014 Stock Option and Incentive Plan [Member] \| Minimum [Member]
Stockholders Equity [Line Items]
Stock options, expected term		5 years 11 months 19 days
Stock options, expected stock price volatility		77.50%
Stock options, risk free rate		1.47%
2014 Stock Option and Incentive Plan [Member] \| Maximum [Member]
Stockholders Equity [Line Items]
Stock options, expected term		6 years 29 days
Stock options, expected stock price volatility		77.70%
Stock options, risk free rate		1.90%
2014 Stock Option and Incentive Plan [Member] \| General and Administrative Expense [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense		$ 269,000	218,000
2014 Stock Option and Incentive Plan [Member] \| Research and Development Expense [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense		197,000	$ 196,000
2004 Stock Option Plan [Member]
Stockholders Equity [Line Items]
Stock options, intrinsic value	$ 0	$ 0
Closing price of common stock	$ 7.40	$ 7.40
Employee Stock Purchase Plan [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense		$ 20,000
Number of shares reserved for future issuance	600,000	600,000				117,100
Percentage of outstanding common stock increased to shares available for grant		1.00%
Number of shares available for issuance	264,233	264,233
Series X Redeemable Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock shares vested					558,862

Equity - Summary of Stock Option Activity (Detail)	3 Months Ended
Equity - Summary of Stock Option Activity (Detail)	Mar. 31, 2016 USD ($) $ / shares shares
2004 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance \| shares	10,917
Number of Shares , Exercised \| shares	0
Number of Shares, Expired \| shares	0
Number of Shares Outstanding, Ending Balance \| shares	10,917
Number of Shares, Options Exercisable \| shares	10,917
Weighted-average years remaining on contractual life	2 years 11 days
Weighted Average Exercise Price Per Share, Beginning Balance \| $ / shares	$ 40.58
Weighted Average Exercise Price Per Share, Exercised \| $ / shares	0
Weighted Average Exercise Price Per Share, Expired \| $ / shares	0
Weighted Average Exercise Price Per Share, Ending Balance \| $ / shares	40.58
Weighted Average Exercise Price Per Share, Options Exercisable \| $ / shares	$ 40.58
Aggregate Intrinsic Value, Granted \| $	$ 0
Aggregate Intrinsic Value, Exercised \| $	0
Aggregate Intrinsic Value, Expired \| $	0
Aggregate Intrinsic Value, Outstanding Ending Balance \| $	$ 0
2014 Stock Option and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance \| shares	1,620,760
Number of Shares , Granted \| shares	796,500
Number of Shares , Exercised \| shares	0
Number of Shares , Cancelled \| shares	(28,000)
Number of Shares Outstanding, Ending Balance \| shares	2,389,260
Number of Shares, Options Exercisable \| shares	515,942
Weighted-average years remaining on contractual life	9 years 2 months 9 days
Unrecognized compensation cost related to non-vested stock options \| $	$ 8,200,000
Weighted Average Exercise Price Per Share, Beginning Balance \| $ / shares	$ 4.95
Weighted Average Exercise Price Per Share, Granted \| $ / shares	7.80
Weighted Average Exercise Price Per Share, Exercised \| $ / shares	0
Weighted Average Exercise Price Per Share, Cancelled \| $ / shares	6.79
Weighted Average Exercise Price Per Share, Ending Balance \| $ / shares	5.87
Weighted Average Exercise Price Per Share, Options Exercisable \| $ / shares	$ 4.52
Aggregate Intrinsic Value, Outstanding Beginning Balance \| $	$ 10,339,000
Aggregate Intrinsic Value, Granted \| $	0
Aggregate Intrinsic Value, Exercised \| $	0
Aggregate Intrinsic Value, Outstanding Ending Balance \| $	4,164,000
Aggregate Intrinsic Value, Options Exercisable \| $	$ 1,485,000

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	May 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Operating Leased Assets [Line Items]
Commencement date of lease	2015-09
Acquisition of leasehold improvements	$ 445
Operating leases, rent expenses			$ 15
Leased Office Building [Member]
Operating Leased Assets [Line Items]
Operating leases, rent expenses		$ 62

Commitments and Contingencies - Schedule of Aggregate Annual Commitments Pursuant to Office Lease and Lease Amendment (Detail) $ in Thousands	Mar. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2016	$ 177
2017	402
2018	411
2019	421
2020	430
Thereafter	959
Total	$ 2,800

Fair Value of Financial Measurements - Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Certificates of Deposit [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	$ 17,932	$ 16,160
Agency Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	5,502	10,031
United States Treasury Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	20,125	5,047
Short-term Investments [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	43,559	31,238
Level 1 [Member] \| United States Treasury Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	20,125	5,047
Level 1 [Member] \| Short-term Investments [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	20,125	5,047
Level 2 [Member] \| Certificates of Deposit [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	17,932	16,160
Level 2 [Member] \| Agency Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	5,502	10,031
Level 2 [Member] \| Short-term Investments [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Short-term investments fair value disclosure	$ 23,434	$ 26,191

Fair Value of Financial Measurements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1,997
Convertible Notes Redemption Rights Derivative [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value of embedded derivative		$ 480
Notes converted in to shares		337,932
Derivative, Gain (Loss) on Derivative, Net	$ 480

Derivative Financial Instruments - Effect of Derivative Instrument Not Designated as Hedging Instruments on Statement of Operations (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2015 USD ($)
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 financial instrument	$ 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 financial instrument	$ 480

Subsequent Event - Additional Information (Detail) - Subsequent Event [Member] - Maximum [Member]	Apr. 30, 2016 USD ($)
Subsequent Event [Line Items]
Amount of stock transactions	$ 200,000,000
Amount of common stock transactions	$ 50,000,000