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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2015	Aug. 06, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
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		20,197,716

Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 49,012	$ 3,618
Prepaid expenses and other current assets	465	52
Total current assets	49,477	3,670
Property and equipment, net	29
Other assets	2,182	1,850
Total assets	51,688	5,520
Current liabilities:
Notes payable, current portion		3,063
Accounts payable	813	1,146
Accrued expenses and other current liabilities	1,273	992
Accrued interest	366
Convertible Bridge Notes		1,541
Convertible Bridge Notes redemption rights derivative		480
Total current liabilities	2,452	7,222
2020 Convertible Notes, net of debt discount of $12,074	8,926
Notes payable, net of current portion		2,550
Warrant liabilities		482
2020 Convertible Notes derivative liability	8,567
Other long-term liabilities	24	24
Total liabilities	19,969	10,278
Redeemable convertible preferred stock		46,801
Commitments and Contingencies (Note 7)
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 June 30, 2015 and December 31, 2014, respectively; 16,327,003 shares and 1,020,088 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	163	10
Additional paid-in capital	163,446	76,472
Accumulated deficit	(131,890)	(128,041)
Total stockholders' equity (deficit)	31,719	(51,559)
Total Liabilities, Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit)	$ 51,688	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) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Convertible notes, debt discount	$ 12,074	$ 12,074
Preferred stock, shares authorized		28,659,924
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	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	$ 0.001	$ 0.001
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	$ 0.001	$ 0.001
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 - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Statements of Operations - USD ($) $ in Thousands	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating expenses:
Research and development	$ (1,954)	$ (1,862)	$ (3,023)	$ (3,412)
General and administrative	(1,728)	(332)	(3,708)	(494)
Loss from operations	(3,682)	(2,194)	(6,731)	(3,906)
Interest expense	(564)	(248)	(1,038)	(491)
Loss on extinguishment of debt			(683)
Change in fair value of warrant liabilities		(405)	267	(598)
Change in fair value of Convertible Bridge Notes redemption rights derivative			480
Change in fair value of 2020 Convertible Notes derivative liability	1,859		3,856
Net loss	$ (2,387)	$ (2,847)	$ (3,849)	$ (4,995)
Net loss per share attributable to common stockholders-basic and diluted	$ (0.15)	$ (3.81)	$ (0.33)	$ (6.89)
Weighted-average number of shares outstanding-basic and diluted	16,327,003	1,020,088	12,026,183	1,020,088

Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Statement of Cash Flows - USD ($) $ in Thousands	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net loss	$ (2,847)	$ (3,849)	$ (4,995)
Adjustments to reconcile net loss to cash used in operating activities:
Noncash interest expense		577	106
Loss on extinguishment of debt		522
Depreciation	0	1	0
Change in fair value of warrant liabilities	405	(267)	598
Change in fair value of Convertible Bridge Notes redemption rights derivative		(480)
Change in fair value of 2020 Convertible Notes derivative liability		(3,856)
Stock-based compensation		1,558	4
Changes in operating assets and liabilities:
Prepaid expenses and other assets		(574)	26
Accounts payable		(333)	130
Accrued expenses and other current liabilities		651	219
Net cash used in operating activities		(6,050)	(3,912)
Cash flows from investing activities:
Purchase of property and equipment		(30)
Net cash used in investing activities:		(30)
Cash flows from financing activities:
Proceeds from issuance of common stock in initial public offering, net of issuance costs		38,115
Proceeds from issuance of 2020 Convertible Notes in initial public offering, net of underwriting discounts		21,000
Payments of 2020 Convertible Notes issuance costs		(1,841)
Principal payments on notes payable		(5,800)
Net cash provided by financing activities:		51,474
Net change in cash and cash equivalents		45,394	(3,912)
Cash and cash equivalents, beginning of period		3,618	12,793
Cash and cash equivalents, end of period	8,881	49,012	8,881
Supplemental disclosure of cash flow information:
Cash paid for interest		89	385
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' 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	$ 1,611		1,611
Accretion of Series AA preferred stock to redemption value		130	$ 419
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	6 Months Ended
Organization and Operations	Jun. 30, 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 $36,525 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 5). 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 June 30, 2015, the Company had an accumulated deficit of $131,890 and cash and cash equivalents of $49,012. The Company estimates that it has sufficient funding to sustain operations through 2016. 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 Policies

6 Months Ended

Jun. 30, 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 and six months ended June 30, 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 assumptions utilized 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, Securities and Exchange Commission (“SEC”) and NASDAQ Global Market (“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 six months ended June 30, 2015, the Company incurred an additional $1,128 of public offering costs and allocated $2,347 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 $55 in the three months ended June 30, 2015 and 2014, respectively, and $92 and $106 in the six months ended June 30, 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, 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 5, 8 and 9).

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 June 30,						For the six months ended June 30,
	2015			2014			2015			2014
	(in thousands, except share and per share data)
Numerator:
Net loss	$	(2,387	)	$	(2,847	)	$	(3,849	)	$	(4,995	)
Accretion and dividends on convertible preferred stock		—			(1,037	)		(130	)		(2,030	)

Net loss applicable to common stockholders		(2,387	)		(3,884	)		(3,979	)		(7,025	)

Denominator:
Weighted average common shares outstanding - basic and diluted		16,327,003			1,020,088			12,026,183			1,020,088

Net loss per share applicable to common stockholders - basic and diluted	$	(0.15	)	$	(3.81	)	$	(0.33	)	$	(6.89	)

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:


	Three months ended June 30,				Six months ended June 30,
	2015		2014		2015		2014
Series AA preferred stock		—		7,037,874		—		7,037,874
Series X preferred stock		—		466,319		—		466,319
Shares issuable upon conversion of the 2020 Convertible Notes		3,333,333		—		3,333,333		—
Warrants exercisable for common stock		56,408		266,428		56,408		266,428
Stock options		1,394,075		11,835		1,394,075		11,835

Total		4,783,816		7,782,456		4,783,816		7,782,456

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.

Property and Equipment, Net

6 Months Ended

Jun. 30, 2015

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

3. Property and Equipment, net

Property and equipment, net, at June 30, 2015 and December 31, 2014, consisted of the following:


	Useful lives	June 30, 2015			December 31, 2014
		(in thousands)

Laboratory equipment	5 years	$	16		$	—
Office equipment	5 years		14			—

			30			—
Less: accumulated depreciation			(1	)

Property and equipment, net		$	29		$	—

Depreciation expense for property and equipment was $1 for the three and six month periods ended June 30, 2015, and $0 for the three and six month periods ended June 30, 2014, respectively.

Accrued Expenses

6 Months Ended

Jun. 30, 2015

Payables and Accruals [Abstract]

Accrued Expenses

4. Accrued Expenses

Accrued expenses at June 30, 2015 and December 31, 2014, consisted of the following:


	June 30, 2015		December 31, 2014
	(in thousands)

Research and development	$	110	$	116
Government payable		436		421
Compensation and benefits		563		293
Professional fees		156		155
Other		8		7

Total	$	1,273	$	992

Debt

6 Months Ended

Jun. 30, 2015

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 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.

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 (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 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, 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, the Company estimated the fair value of the conversion option including make-whole and the Additional Interest using the “with” and “without” method. Using this methodology, the Company 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. 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 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.

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 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 June 30, 2015, the fair value of the combined embedded derivative liability was $8,567. The change in the estimated fair value of the combined embedded derivative liability for the three and six months ended June 30, 2015, was $1,859 and $3,856, respectively. Interest expense related to the 2020 Convertible Notes for the three months ended June 30, 2015, was $565, including $44 related to amortization of the issuance costs and $259 related to amortization of the debt discount. Interest expense related to the 2020 Convertible Notes for the six months ended June 30, 2015, was $774, including $59 related to amortization of the issuance costs and $349 related to amortization of the debt discount. As of June 30, 2015, the balance of debt discount and issuance costs were $12,074 and $2,038, respectively. At June 30, 2015, interest accrued on the 2020 Convertible Notes was $366 and is reflected in accrued interest on the balance sheet.

The following table summarizes how the 2020 Convertible Notes are reflected on the balance sheet at June 30, 2015:


	June 30, 2015
	(in thousands)

Gross proceeds	$	21,000
Initial value of embedded derivatives		(12,423	)
Amortization of debt discount		349

Carrying value	$	8,926

In July and August 2015, the 2020 Convertible Notes fully converted into shares of common stock (see Note 11).

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. For the six months ended June 30, 2015, the Company reflected 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 the six months ended June 30, 2015, in connection with the conversion of the Convertible Bridge Notes into common stock, the Company reflected 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 six months ended June 30, 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 six months ended June 30, 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 June 30, 2014, interest expense related to the Loan Agreements was $248, including $55 related to accretion of the debt discount and termination payment. For the six months ended June 30, 2014, interest expense related to the Loan Agreements was $491, including $106 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 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 six months ended June 30, 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 six months ended June 30, 2015.

Equity

6 Months Ended

Jun. 30, 2015

Equity [Abstract]

Equity

6. 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 these conversions, 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 six months ended June 30, 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 of Directors. At June 30, 2015 and December 31, 2014, there were 16,327,003 and 1,020,088 shares of 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 the remaining 75% will vest equally over the following 36 monthly anniversaries. Additionally on August 28, 2014, the Board of Directors granted an aggregate of 59,142 stock options to the directors that were fully vested on the date of the grant.

The fair value of the stock options granted during 2014 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 six months ended June 30, 2015, reflects stock compensation expense calculated from the grant date in August 2014 through June 30, 2015.

During the three and six months ended June 30, 2015, the Board of Directors granted a total of 483,000, ten-year term, stock options to employees and directors 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 5.31 to 6.08 years; expected stock price volatility of 97.6% to 101.1%; a risk free rate of 1.63% to 1.85%; and a dividend yield of 0%. The Company will recognize $1,983 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 six months ended June 30, 2015, under the 2014 Plan:


	Number of Shares		Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value

Options outstanding at December 31, 2014		900,117	$	4.342	$	970
Granted during the period		483,000		5.190		—
Exercised during the period		—		—		—
Expired during the period		—		—		—

Options outstanding at June 30, 2015		1,383,117	$	4.638	$	502


Options exercisable at June 30, 2015		59,142	$	4.342	$	33

Weighted-average years remaining on contractual life		9.5
Unrecognized compensation cost related to non-vested stock options	$	4,176

Aggregate intrinsic value is based on $4.90 per share, the closing price of common stock on June 30, 2015.

For the three months ended June 30, 2015, the Company recorded aggregate stock compensation expense of $194, of which $98 was recorded in general and administrative expense and $96 in research and development expense. For the six months ended June 30, 2015, the Company recorded aggregate stock compensation expense of $608, of which $316 was recorded in general and administrative expense and $292 in research and development expense.

2004 Stock Option and Incentive Plan

The Company has outstanding stock options pursuant to its 2004 Stock Option and Incentive Plan. The following table summarizes activity for the six months ended June 30, 2015, under the 2004 Plan:


	Number of Shares		Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value

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 June 30, 2015		10,958	$	40.578	$	—


Options exercisable at June 30, 2015		10,958	$	40.578	$	—

Weighted-average years remaining on contractual life		2.8
Unrecognized compensation cost related to non-vested stock options	$	—

The exercise price exceeds the $4.90 closing price of common stock on June 30, 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 (“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 June 30, 2015, no shares have been issued pursuant to the ESPP.

- 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Subparagraph (SX 210.4-08.(d),(e))
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies *Operating leases* The Company leases office space in Lexington, Massachusetts under a lease agreement expiring in September 2015. Rent expense for the three and six months ended June 30, 2015, was $20 and $35, respectively. Rent expense for the three and six months ended June 30, 2014, was $12 and $27, respectively. In May 2015, the Company entered into a lease agreement for 11,125 square feet for its new headquarters in Lexington, Massachusetts. The Company expects to occupy this space in September 2015, at which time its rental obligations will commence. The lease term is 90 months and the Company has the right to extend the term for one period of five years. Aggregate rental payments over the term of the lease are approximately $2,100, including approximately $209 due in the first twelve months of the lease. The lease also provides that the Company will be responsible for the operating expenses and real estate taxes, to the extent in excess of base-year amounts, and electricity attributable to the premises. *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 Measurements

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value of Financial Measurements

8. 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 liability.

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 June 30, 2015
	Total		Level 1		Level 2		Level 3
Liabilities:
2020 Convertible Notes derivative liability	$	8,567	$	—	$	—	$	8,567


	Fair Value Measurements at December 31, 2014
	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 liability

The fair value methodologies related to the 2020 Convertible Notes derivative liability are discussed in Note 5.

Convertible preferred stock warrant liability

As of December 31, 2013, June 30, 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, June 30, 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, June 30, 2014, and December 31, 2014:


	December 31, 2013	June 30, 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	0.00%	0.00%	0.00%
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.

Convertible Bridge Notes redemption rights derivative

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 six months ended June 30, 2015 and 2014:


	Convertible preferred stock warrant liabilities			Convertible Bridge Notes redemption rights derivative			2020 Convertible Notes derivative liability

Balance at December 31, 2014	$	482		$	480		$	—
Issuance of 2020 Convertible Notes		—			—			12,423
Change in fair value		(267	)		(480	)		(3,856	)
Reclassification to stockholders’ equity		(215	)		—			—

Balance at June 30, 2015		—			—			8,567


	Convertible preferred stock warrant liabilities		Convertible Bridge Notes redemption rights derivative		2020 Convertible Notes derivative liability

Balance at December 31, 2013	$	1,888	$	—	$	—
Change in fair value		598		—		—

Balance at June 30, 2014		2,486		—		—

Derivative Financial Instruments

6 Months Ended

Jun. 30, 2015

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.

Fair values of derivative instruments not designated as hedging instruments consist of the following:


Liability derivative financial instruments	Balance Sheet Location	Fair Value

December 31, 2014:
Convertible Bridge Notes redemption rights derivative	Convertible Bridge Notes redemption rights derivative	$	480


June 30, 2015:
2020 Convertible Notes derivative liability	2020 Convertible Notes derivative liability	$	8,567

The effect of derivative instruments not designated as hedging instruments on the statement of operations for the three and six months ended June 30, 2015, consist of the following:


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
		For the three months ended June 30, 2015		For the six months ended June 30, 2015

2020 Convertible Notes derivative liability	Change in fair value of 2020 Convertible Notes derivative liability	$	1,859	$	3,856


Convertible Bridge Notes	Change in fair value of Convertible Bridge Notes redemption rights derivative	$	—	$	480

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.

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-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 815
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-Paragraph 4J
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-Name Accounting Standards Codification
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-Paragraph 4A
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-Name Accounting Standards Codification
-Topic 815
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-Section 50
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Reference 18: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 815
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Management Incentive Plan	6 Months Ended
Management Incentive Plan	Jun. 30, 2015
Compensation Related Costs [Abstract]
Management Incentive Plan	10. 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.

- Definition

The entire disclosure for compensation costs, including compensated absences accruals, compensated absences liability, deferred compensation arrangements and income statement compensation items. Deferred compensation arrangements may include a description of an arrangement with an individual employee, which is generally an employment contract between the entity and a selected officer or key employee containing a promise by the employer to pay certain amounts at designated future dates, usually including a period after retirement, upon compliance with stipulated requirements. This type of arrangement is distinguished from broader based employee benefit plans as it is usually tailored to the employee. Disclosure also typically includes the amount of related compensation expense recognized during the reporting period, the number of shares (units) issued during the period under such arrangements, and the carrying amount as of the balance sheet date of the related liability.

+ References + Details

Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2015
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events *2020 Convertible Notes* In July and August 2015, holders of $21.0 million principal amount of the 2020 Convertible Notes elected to convert the principal into approximately 3.33 million shares of common stock. In addition, the Make-Whole Interest Payment was settled with shares of common stock, at the election of the Company, resulting in the issuance of approximately 0.53 million additional shares of common stock. *S-1 Registration Statement* On July 31, 2015, the Company filed a registration statement with the SEC on Form S-1 to sell up to $57.5 million of our common stock.

Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2015

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Cash and Cash Equivalents

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

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 June 30,						For the six months ended June 30,
	2015			2014			2015			2014
	(in thousands, except share and per share data)
Numerator:
Net loss	$	(2,387	)	$	(2,847	)	$	(3,849	)	$	(4,995	)
Accretion and dividends on convertible preferred stock		—			(1,037	)		(130	)		(2,030	)

Net loss applicable to common stockholders		(2,387	)		(3,884	)		(3,979	)		(7,025	)

Denominator:
Weighted average common shares outstanding - basic and diluted		16,327,003			1,020,088			12,026,183			1,020,088

Net loss per share applicable to common stockholders - basic and diluted	$	(0.15	)	$	(3.81	)	$	(0.33	)	$	(6.89	)

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:


	Three months ended June 30,				Six months ended June 30,
	2015		2014		2015		2014
Series AA preferred stock		—		7,037,874		—		7,037,874
Series X preferred stock		—		466,319		—		466,319
Shares issuable upon conversion of the 2020 Convertible Notes		3,333,333		—		3,333,333		—
Warrants exercisable for common stock		56,408		266,428		56,408		266,428
Stock options		1,394,075		11,835		1,394,075		11,835

Total		4,783,816		7,782,456		4,783,816		7,782,456

Subsequent Events

Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 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 June 30,						For the six months ended June 30,
	2015			2014			2015			2014
	(in thousands, except share and per share data)
Numerator:
Net loss	$	(2,387	)	$	(2,847	)	$	(3,849	)	$	(4,995	)
Accretion and dividends on convertible preferred stock		—			(1,037	)		(130	)		(2,030	)

Net loss applicable to common stockholders		(2,387	)		(3,884	)		(3,979	)		(7,025	)

Denominator:
Weighted average common shares outstanding - basic and diluted		16,327,003			1,020,088			12,026,183			1,020,088

Net loss per share applicable to common stockholders - basic and diluted	$	(0.15	)	$	(3.81	)	$	(0.33	)	$	(6.89	)

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:


	Three months ended June 30,				Six months ended June 30,
	2015		2014		2015		2014
Series AA preferred stock		—		7,037,874		—		7,037,874
Series X preferred stock		—		466,319		—		466,319
Shares issuable upon conversion of the 2020 Convertible Notes		3,333,333		—		3,333,333		—
Warrants exercisable for common stock		56,408		266,428		56,408		266,428
Stock options		1,394,075		11,835		1,394,075		11,835

Total		4,783,816		7,782,456		4,783,816		7,782,456

Property and Equipment, Net (Tables)

6 Months Ended

Jun. 30, 2015

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net, at June 30, 2015 and December 31, 2014, consisted of the following:


	Useful lives	June 30, 2015			December 31, 2014
		(in thousands)

Laboratory equipment	5 years	$	16		$	—
Office equipment	5 years		14			—

			30			—
Less: accumulated depreciation			(1	)

Property and equipment, net		$	29		$	—

Accrued Expenses (Tables)

6 Months Ended

Jun. 30, 2015

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses at June 30, 2015 and December 31, 2014, consisted of the following:


	June 30, 2015		December 31, 2014
	(in thousands)

Research and development	$	110	$	116
Government payable		436		421
Compensation and benefits		563		293
Professional fees		156		155
Other		8		7

Total	$	1,273	$	992

Debt (Tables)

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Summary of Issuance of Convertible Notes

The following table summarizes how the 2020 Convertible Notes are reflected on the balance sheet at June 30, 2015:


	June 30, 2015
	(in thousands)

Gross proceeds	$	21,000
Initial value of embedded derivatives		(12,423	)
Amortization of debt discount		349

Carrying value	$	8,926

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

+ Details

Equity (Tables)

6 Months Ended

Jun. 30, 2015

Equity [Abstract]

Summary of Stock Option Activity

The following table summarizes activity for the six months ended June 30, 2015, under the 2014 Plan:


	Number of Shares		Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value

Options outstanding at December 31, 2014		900,117	$	4.342	$	970
Granted during the period		483,000		5.190		—
Exercised during the period		—		—		—
Expired during the period		—		—		—

Options outstanding at June 30, 2015		1,383,117	$	4.638	$	502


Options exercisable at June 30, 2015		59,142	$	4.342	$	33

Weighted-average years remaining on contractual life		9.5
Unrecognized compensation cost related to non-vested stock options	$	4,176

Aggregate intrinsic value is based on $4.90 per share, the closing price of common stock on June 30, 2015.

The Company has outstanding stock options pursuant to its 2004 Stock Option and Incentive Plan. The following table summarizes activity for the six months ended June 30, 2015, under the 2004 Plan:


	Number of Shares		Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value

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 June 30, 2015		10,958	$	40.578	$	—


Options exercisable at June 30, 2015		10,958	$	40.578	$	—

Weighted-average years remaining on contractual life		2.8
Unrecognized compensation cost related to non-vested stock options	$	—

Fair Value of Financial Measurements (Tables)

6 Months Ended

Jun. 30, 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 June 30, 2015
	Total		Level 1		Level 2		Level 3
Liabilities:
2020 Convertible Notes derivative liability	$	8,567	$	—	$	—	$	8,567


	Fair Value Measurements at December 31, 2014
	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, June 30, 2014, and December 31, 2014:


	December 31, 2013	June 30, 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	0.00%	0.00%	0.00%
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 six months ended June 30, 2015 and 2014:


	Convertible preferred stock warrant liabilities			Convertible Bridge Notes redemption rights derivative			2020 Convertible Notes derivative liability

Balance at December 31, 2014	$	482		$	480		$	—
Issuance of 2020 Convertible Notes		—			—			12,423
Change in fair value		(267	)		(480	)		(3,856	)
Reclassification to stockholders’ equity		(215	)		—			—

Balance at June 30, 2015		—			—			8,567


	Convertible preferred stock warrant liabilities		Convertible Bridge Notes redemption rights derivative		2020 Convertible Notes derivative liability

Balance at December 31, 2013	$	1,888	$	—	$	—
Change in fair value		598		—		—

Balance at June 30, 2014		2,486		—		—

Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 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 derivative financial instruments	Balance Sheet Location	Fair Value

December 31, 2014:
Convertible Bridge Notes redemption rights derivative	Convertible Bridge Notes redemption rights derivative	$	480


June 30, 2015:
2020 Convertible Notes derivative liability	2020 Convertible Notes derivative liability	$	8,567

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 and six months ended June 30, 2015, consist of the following:


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
		For the three months ended June 30, 2015		For the six months ended June 30, 2015

2020 Convertible Notes derivative liability	Change in fair value of 2020 Convertible Notes derivative liability	$	1,859	$	3,856


Convertible Bridge Notes	Change in fair value of Convertible Bridge Notes redemption rights derivative	$	—	$	480

Organization and Operations - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 28, 2015	Mar. 31, 2015	Jun. 30, 2015	Mar. 24, 2015	Feb. 23, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Schedule Of Description Of Business [Line Items]
Net proceeds from issuance of equity		$ 36,525,000
Net proceeds from issuance of debts		$ 18,903,000
Accumulated deficit			$ (131,890,000)			$ (128,041,000)
Cash and cash equivalents			$ 49,012,000			$ 3,618,000	$ 8,881,000	$ 12,793,000
Estimated period of available funds to run normal organizational operations			Through 2016
2020 Convertible Notes [Member]
Schedule Of Description Of Business [Line Items]
Convertible senior notes, interest rate, stated percentage			5.00%
Aggregate principal amount				$ 1,000,000	$ 20,000,000
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	$ 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	$ 6.00
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		$ 6.00
Over-Allotment Option [Member] \| Senior Notes [Member] \| 2020 Convertible Notes [Member]
Schedule Of Description Of Business [Line Items]
Aggregate principal amount		$ 1,000,000

Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Summary Of Significant Accounting Policy [Line Items]
Deferred public offering costs	$ 1,128		$ 1,128		$ 1,846
Amortization of deferred financing costs	44	$ 55	92	$ 106
Equity Offering [Member]
Summary Of Significant Accounting Policy [Line Items]
Deferred public offering costs	2,347		2,347
Debt Offering [Member]
Summary Of Significant Accounting Policy [Line Items]
Deferred public offering costs	$ 627		$ 627

Significant Accounting Policies - Schedule of Computation of Basic and Diluted Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator:
Net loss	$ (2,387)	$ (2,847)	$ (3,849)	$ (4,995)
Accretion and dividends on convertible preferred stock		(1,037)	(130)	(2,030)
Net loss applicable to common stockholders	$ (2,387)	$ (3,884)	$ (3,979)	$ (7,025)
Denominator:
Weighted average common shares outstanding - basic and diluted	16,327,003	1,020,088	12,026,183	1,020,088
Net loss per share applicable to common stockholders - basic and diluted	$ (0.15)	$ (3.81)	$ (0.33)	$ (6.89)

- 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		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,783,816	7,782,456	4,783,816	7,782,456
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		7,037,874		7,037,874
Series X Preferred [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		466,319		466,319
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		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	266,428	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	1,394,075	11,835	1,394,075	11,835

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 30
Less: accumulated depreciation	(1)
Property and equipment, net	$ 29
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	5 years
Property and equipment, Gross	$ 16
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Useful lives	5 years
Property and equipment, Gross	$ 14

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Property, Plant and Equipment, Net [Abstract]
Depreciation expense	$ 1	$ 0	$ 1	$ 0

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Research and development	$ 110	$ 116
Government payable	436	421
Compensation and benefits	563	293
Professional fees	156	155
Other	8	7
Total	$ 1,273	$ 992

Debt - 2020 Convertible Notes - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) $ / shares	Jun. 30, 2014 USD ($)	Mar. 24, 2015 USD ($)	Feb. 23, 2015 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Interest expense	$ 564,000	$ 248,000	$ 1,038,000	$ 491,000
Debt instrument, unamortized discount	12,074,000		12,074,000				$ 12,074,000
Accrued interest	$ 366,000		$ 366,000
2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 1,000,000	$ 20,000,000
Debt instrument maturity date			Feb. 15, 2020
Convertible notes, interest rate, stated percentage	5.00%		5.00%
Financing costs incurred by the company			$ 2,097,000
Number of shares, note gets converted into			158.7302
Principal amount	$ 1,000		$ 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	8,567,000		$ 8,567,000			$ 11,850,000
Derivative liabilities and discount recorded					$ 573,000
Change in estimated fair value of combined embedded derivative liability	1,859,000		3,856,000
Interest expense	565,000		774,000
Amortization of financing costs and discounts	44,000		59,000
Amortization of debt discount	259,000		349,000
Debt instrument, unamortized discount	12,074,000		12,074,000
Unamortized debt issuance expense	2,038,000		2,038,000
Accrued interest	$ 366,000		$ 366,000
2020 Convertible Notes [Member] \| First 90 Days [Member]
Debt Instrument [Line Items]
Additional interest rate	0.25%		0.25%
2020 Convertible Notes [Member] \| 91 to 180 Days [Member]
Debt Instrument [Line Items]
Additional interest rate	0.50%		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 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 - Summary of Issuance of Convertible Notes (Detail) $ in Thousands	Jun. 30, 2015 USD ($)
Debt Instrument [Line Items]
Carrying value	$ 8,926
2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Gross proceeds	21,000
Initial value of embedded derivatives	(12,423)
Amortization of debt discount	349
Carrying value	$ 8,926

Debt - Convertible Bridge Notes - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended		6 Months Ended
	Feb. 28, 2015	Dec. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Debt Instrument [Line Items]
Amortization of financing costs			$ 44,000	$ 55,000	$ 92,000	$ 106,000
Losses on extinguishment of debt					$ (522,000)
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%		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
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	6 Months Ended
Debt - Notes Payable - Additional Information (Detail)	Jun. 28, 2013 USD ($) Agreement Entity	Feb. 28, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Installment $ / shares shares	Jun. 30, 2014 USD ($)	Jan. 31, 2015 USD ($)
Debt Instrument [Line Items]
Losses on extinguishment of debt				$ (522,000)
Change in fair value of warrant liabilities			$ (405,000)	$ 267,000	$ (598,000)
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
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
Losses on extinguishment of debt				$ (322,000)
Interest expense related to loan agreements			248,000	115,000	491,000
Accretion of debt discounts and termination payment			$ 55,000	$ 26,000	$ 106,000
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)		1 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended	48 Months Ended
Equity - Additional Information (Detail)	Aug. 28, 2014 $ / shares shares	Jan. 31, 2015	Nov. 30, 2014	Jun. 30, 2015 USD ($) $ / shares shares	Jun. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Aug. 30, 2018 USD ($)	Feb. 28, 2015 $ / shares shares
Stockholders Equity [Line Items]
Common stock, shares authorized				120,000,000	120,000,000	43,509,727		120,000,000
Common stock, par value \| $ / shares				$ 0.01	$ 0.01	$ 0.01		$ 0.01
Preferred stock, shares authorized						28,659,924
Preferred stock, par value \| $ / shares				$ 0.001	$ 0.001	$ 0.001		$ 0.001
Preferred stock, shares authorized				5,000,000	5,000,000	5,000,000		5,000,000
Reverse stock split, conversion ratio		1.197	3.390
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
Stock-based compensation expense \| $				$ 194,000	$ 608,000
Common stock voting rights description					One vote per share
Common stock, shares outstanding				16,327,003	16,327,003	1,020,088
Stock options granted				483,000,000	483,000,000
Expiration period of stock options				10 years	10 years
2014 Stock Option and Incentive Plan [Member]
Stockholders Equity [Line Items]
Preferred stock shares vested	59,142
Percentage of outstanding common stock increased to shares available for grant					13.70%
Number of shares available for grant				2,175,216	2,175,216
Stock options granted	840,975				483,000
Expiration period of stock options	10 years
Exercise price of stock options granted \| $ / shares	$ 4.342				$ 5.190
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 36 monthly anniversaries.
Additional stock options granted	59,142
Stock options, dividend yield					0.00%
Closing price of common stock \| $ / shares				$ 4.90	$ 4.90
Stock options, intrinsic value \| $				$ 502,000	$ 502,000	$ 970,000
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 36 Monthly Anniversaries [Member]
Stockholders Equity [Line Items]
Stock options, vesting percentage	75.00%
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%
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%
2004 Stock Option Plan [Member]
Stockholders Equity [Line Items]
Closing price of common stock \| $ / shares				$ 4.90	$ 4.90
Stock options, intrinsic value \| $				$ 0	$ 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	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	600,000
Black-Scholes Stock Option Pricing Model [Member] \| Directors and Employees [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense \| $				$ 1,983,000
Stock options, dividend yield				0.00%	0.00%
Black-Scholes Stock Option Pricing Model [Member] \| Directors and Employees [Member] \| Maximum [Member]
Stockholders Equity [Line Items]
Expiration period of stock options				6 years 29 days	6 years 29 days
Stock options, expected stock price volatility				101.10%	101.10%
Stock options, risk free rate				1.85%	1.85%
Black-Scholes Stock Option Pricing Model [Member] \| Directors and Employees [Member] \| Minimum [Member]
Stockholders Equity [Line Items]
Expiration period of stock options				5 years 3 months 22 days	5 years 3 months 22 days
Stock options, expected stock price volatility				97.60%	97.60%
Stock options, risk free rate				1.63%	1.63%
Scenario, Forecast [Member] \| 2014 Stock Option and Incentive Plan [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense \| $							$ 2,798,000
General and Administrative Expense [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense \| $				$ 98,000	$ 316,000
Research and Development Expense [Member]
Stockholders Equity [Line Items]
Stock-based compensation expense \| $				$ 96,000	292,000
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	0	25,757,874
Preferred stock, shares outstanding				0	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 \| $ / shares				$ 75	$ 75
Redeemable convertible preferred stock \| $				$ 46,383,000	$ 46,383,000
Preferred stock, additional paid in capital \| $				$ 46,308,000	$ 46,308,000
Series X Redeemable Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares authorized				0	0	2,902,050
Preferred stock, shares outstanding				0	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 \| $ / shares				$ 5	$ 5
Redeemable convertible preferred stock \| $				$ 548,000	$ 548,000
Preferred stock, additional paid in capital \| $				$ 543,000	$ 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	25,949,333

Equity - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
	Aug. 28, 2014	Jun. 30, 2015	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares , Granted		483,000,000	483,000,000
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		483,000
Number of Shares , Exercised			0
Number of Shares , Expired			0
Number of Shares Outstanding, Ending Balance		1,383,117	1,383,117
Number of Shares, Options Exercisable		59,142	59,142
Weighted-average years remaining on contractual life			9 years 6 months
Unrecognized compensation cost related to non-vested stock options		$ 4,176	$ 4,176
Weighted Average Exercise Price Per Share, Beginning Balance			$ 4.342
Weighted Average Exercise Price Per Share, Granted	$ 4.342		5.190
Weighted Average Exercise Price Per Share, Exercised			0
Weighted Average Exercise Price Per Share, Expired			0
Weighted Average Exercise Price Per Share, Ending Balance		$ 4.638	4.638
Weighted Average Exercise Price Per Share, Options Exercisable		$ 4.342	$ 4.342
Aggregate Intrinsic Value, Outstanding Beginning Balance			$ 970
Aggregate Intrinsic Value, Granted			0
Aggregate Intrinsic Value, Exercised			0
Aggregate Intrinsic Value, Expired			0
Aggregate Intrinsic Value, Outstanding Ending Balance		$ 502	502
Aggregate Intrinsic Value, Options Exercisable		$ 33	$ 33
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 , Exercised			0
Number of Shares , Expired			0
Number of Shares Outstanding, Ending Balance		10,958	10,958
Number of Shares, Options Exercisable		10,958	10,958
Weighted-average years remaining on contractual life			2 years 9 months 18 days
Weighted Average Exercise Price Per Share, Beginning Balance			$ 40.578
Weighted Average Exercise Price Per Share, Exercised			0
Weighted Average Exercise Price Per Share, Expired			0
Weighted Average Exercise Price Per Share, Ending Balance		$ 40.578	40.578
Weighted Average Exercise Price Per Share, Options Exercisable		$ 40.578	$ 40.578
Aggregate Intrinsic Value, Granted			$ 0
Aggregate Intrinsic Value, Exercised			0
Aggregate Intrinsic Value, Expired			0
Aggregate Intrinsic Value, Outstanding Ending Balance		$ 0	$ 0

Commitments and Contingencies - Additional Information (Detail) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2015 USD ($) ft²	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating leases, rent expenses	$ 2,100	$ 20	$ 12	$ 35	$ 27
Area of leased office space \| ft²	11,125
Lease payment agreement				Aggregate rental payments over the term of the lease are approximately $2,100, including approximately $209 due in the first twelve months of the lease.
Expected commencement date of lease	2015-09
Lease extension term	5 years
Lease description				The lease term is 90 months and the Company has the right to extend the term for one period of five years.
Lease term	90 months
Operating leases, future payments due	$ 209

Fair Value of Financial Measurements - Fair Value of Liabilities Measured on Recurring Basis (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
2020 Convertible Notes Derivative Liability [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure	$ 8,567
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 Liability [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total liability fair value disclosure	$ 8,567
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 Measurements - Schedule of Assumptions Used to Estimate Fair Value of Series AA Preferred Stock Warrants (Detail) - Convertible Preferred Stock Warrant Liability [Member]	6 Months Ended	12 Months Ended
	Jun. 30, 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 Measurements - Additional Information (Detail) - Convertible Bridge Notes Redemption Rights Derivative [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2014 USD ($)
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 Measurements - Schedule of Change in Company's Level 3 Liabilities (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 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)	598
Reclassification to stockholders' equity	(215)
Ending Balance		$ 2,486
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 Liability [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	(3,856)
Ending Balance	$ 8,567

Derivative Financial Instruments - Summary of Fair Values of Derivative Instruments Not Designated as Hedging Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
2020 Convertible Notes Derivative Liability [Member]
Derivatives, Fair Value [Line Items]
Liability derivative financial instruments at fair value	$ 8,567
Convertible Bridge Notes Redemption Rights Derivative [Member]
Derivatives, Fair Value [Line Items]
Liability derivative financial instruments at fair value		$ 480

Derivative Financial Instruments - Effect of Derivative Instrument Not Designated as Hedging Instruments on Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 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 financial instrument	$ 1,859	$ 3,856
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

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%

Subsequent Events - Additional Information (Detail) - USD ($) shares in Thousands	1 Months Ended
	Aug. 31, 2015	Jul. 31, 2015	Jun. 28, 2013
Subsequent Event [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Amount of common stock transactions		$ 57,500,000
Notes Payable [Member]
Subsequent Event [Line Items]
Debt instrument principal amount			$ 3,500,000
Notes Payable [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Debt instrument principal amount	$ 21,000,000	$ 21,000,000
Convertible Notes converted into shares	3,330	3,330
Additional shares of common stock	530	530