Genocea Biosciences (GNCAQ) 10-Q 8 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	4-May-15
Document and Entity Information
Entity Registrant Name	GENOCEA BIOSCIENCES, INC.
Entity Central Index Key	1457612
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		24,149,547
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

Balance_Sheets

Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$57,471	$20,058
Marketable securities	27,022	27,021
Prepaid expenses and other current assets	1,132	963
Total current assets	85,625	48,042
Property and equipment, net	2,137	1,956
Restricted cash	316	316
Other assets	338	117
Total assets	88,416	50,431
Current liabilities:
Accounts payable	2,758	2,692
Accrued expenses and other current liabilities	3,262	2,486
Deferred revenue	556	555
Current portion of long-term debt	1,102
Current portion of deferred rent	116	107
Total current liabilities	7,794	5,840
Non-current liabilities:
Long-term debt, net of current portion	10,480	11,488
Deferred rent, net of current portion	136	168
Deferred revenue, net of current portion	228	350
Other non-current liabilities	32	78
Total liabilities	18,670	17,924
Commitments and contingencies (Note 6)
Stockholders' equity:
Preferred stock, $0.001 par value; Authorized - 25,000 shares; Issued and outstanding - 0 shares at March 31, 2015 and December 31, 2014, respectively
Common stock, $0.001 par value; Authorized - 175,000 shares; Issued - 24,152 and 17,869 shares at March 31, 2015 and December 31, 2014, respectively	24	18
Additional paid-in-capital	197,229	147,923
Accumulated other comprehensive income (loss)	4	-7
Accumulated deficit	-127,511	-115,427
Total stockholders' equity	69,746	32,507
Total liabilities and stockholders' equity	$88,416	$50,431

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Preferred stock
Preferred stock, par value (in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	175,000,000	175,000,000
Common stock, shares issued	24,152,291	17,869,000
Common stock, shares outstanding	24,137,395	17,852,000

Statements_of_Operations

Statements of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Condensed Statements of Operations and Comprehensive Loss
Grant revenue	$121
Operating expenses:
Research and development	8,509	4,407
General and administrative	3,389	1,966
Total operating expenses	11,898	6,373
Loss from operations	-11,777	-6,373
Other expense:
Change in fair value of warrant		-725
Interest expense, net	-307	-231
Other expense	-307	-956
Net loss	-12,084	-7,329
Reconciliation of net loss to net loss attributable to common stockholders
Net loss	-12,084	-7,329
Accretion of redeemable convertible preferred stock to redemption value		-180
Net loss attributable to common stockholders	($12,084)	($7,509)
Net loss per share attributable to common stockholders-basic and diluted (in dollars per share)	($0.64)	($0.76)
Weighted-average number of common shares used in net loss per share attributable to common stockholders - basic and diluted (in shares)	18,834	9,859

Statements_of_Comprehensive_Lo

Statements of Comprehensive Loss (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Condensed Statements of Comprehensive Loss
Net loss	($12,084)	($7,329)
Other comprehensive income:
Unrealized gain on available-for-sale securities	11
Comprehensive loss	($12,073)	($7,329)

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities
Net loss	($12,084)	($7,329)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	180	78
Stock-based compensation	915	881
Net amortization of premium on investments	10
Change in fair value of warrants liability		725
Non-cash interest expense	101	16
Changes in operating assets and liabilities:
Restricted cash		-158
Prepaid expenses and other current assets	-139	-435
Other long-term assets	-174	723
Accounts payable	-143	-1,095
Deferred revenue	-121
Accrued expenses and other liabilities	729	60
Deferred rent	-22	-15
Accrued interest payable		15
Net cash used in operating activities	-10,748	-6,534
Investing activities
Purchases of property and equipment	-232	-27
Net cash used in investing activities	-232	-27
Financing activities
Proceeds from IPO, net of issuance costs		60,133
Proceeds from underwritten public offering, net of issuance costs	48,367
Proceeds from exercise of stock options	26	26
Proceeds form the exercise of warrants		33
Net cash provided by financing activities	48,393	60,192
Net increase in cash and cash equivalents	37,413	53,631
Cash and cash equivalents at beginning of period	20,058	12,208
Cash and cash equivalents at end of period	57,471	65,839
Supplemental cash flow information
Cash paid for interest	218	174
Supplemental disclosure of non-cash investing and financing activities
Conversion of preferred stock to common stock upon closing of IPO		81,774
Reclassification of prepaid IPO closing costs from non-current assets to additional paid-in capital		997
Reclassification of warrants to additional paid-in capital		1,381
Accretion of redeemable convertible preferred stock to redemption value		180
Vesting of restricted stock		$3

Organization_and_operations

Organization and operations	3 Months Ended
	Mar. 31, 2015
Organization and operations
Organization and operations
	1. Organization and operations
	The company
	Genocea Biosciences, Inc. (the “Company”) is a clinical stage biopharmaceutical company that was incorporated in Delaware on August 16, 2006 and has a principal place of business in Cambridge, Massachusetts. The Company has two products in clinical development:
		·	GEN-003, an immunotherapy to treat patients with genital herpes. The Company has completed enrollment in a Phase 2 dose optimization clinical trial and expects to report top-line viral shedding and genital lesion rate changes from baseline for each dose group for the 28-day monitoring period after vaccination late in the second quarter of 2015.
		·	GEN-004, a universal vaccine which is being developed to prevent infections caused by all serotypes of pneumococcus. The Company has completed enrollment in a Phase 2 human challenge clinical trial and expects to report top-line data in the fourth quarter of 2015.
	The Company also has other product candidates that are currently in preclinical development. The Company developed GEN-003, GEN-004 and its preclinical product candidates using its proprietary platform technology called the AnTigen Lead Acquisition System (“ATLAS™”). The ATLAS™ platform mimics the human T cell immune response in the laboratory, which could potentially improve the effectiveness of vaccine discovery and reduce the time needed to create promising vaccines.
	Underwritten public offering
	On March 17, 2015, the Company completed an underwritten public offering of its common stock, $0.001 par value per share (“Common Stock”), pursuant to a shelf registration statement on Form S-3 (the “Registration Statement”), filed with the SEC on March 2, 2015 and a related final prospectus supplement filed on March 12, 2015. An aggregate of 6,272,726 shares of Common Stock, including the exercise in full by the underwriters of their option to purchase an additional 818,181 shares of Common Stock, registered under the Registration Statement were sold at the public offering price of $8.25 per share. Net proceeds of the underwritten public offering, after deducting the underwriting discounts and commissions, were $48.6 million, excluding offering expenses of $276 thousand incurred by the Company.
	At-the-market equity offering program
	In March 2015, the Company established an at-the-market (“ATM”) equity offering program pursuant to which it is able to offer and sell up to $40 million of its common stock at prevailing market prices from time to time. As of March 31, 2015, the Company had not commenced sales under this program.

Summary_of_significant_account

Summary of significant accounting policies	3 Months Ended
	Mar. 31, 2015
Summary of significant accounting policies
Summary of significant accounting policies
	2. Summary of significant accounting policies
	Basis of presentation and use of estimates
	The accompanying condensed financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. These interim condensed financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended March 31, 2015 and 2014.
	The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full fiscal year. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2014 and the notes thereto which are included in the Company’s Annual Report on Form 10-K, as filed with the SEC on February 27, 2015.
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, estimates related to prepaid and accrued research and development expenses, stock-based compensation expense, the valuation of common stock warrants and warrants to purchase redeemable securities, and reported amounts of revenues and expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
	Cash, cash equivalents and marketable securities
	The Company considers all highly liquid investments with maturities of 90 days or less from the purchase date to be cash equivalents. Cash and cash equivalents are held in depository and money market accounts and are reported at fair value.
	Marketable securities consist of U.S. treasury securities with maturities of more than 90 days. The Company has determined the appropriate balance sheet classification of the securities as current since they are available for use in current operating activities, regardless of actual maturity dates. Marketable securities are classified as available-for-sale pursuant to FASB ASC Topic 320, Investments — Debt and Equity Securities,(“ASC 320”) and are recorded on the balance sheet at fair value with unrealized gains and losses (excluding other-than-temporary impairments) reported as a separate component of accumulated other comprehensive income (loss). Realized gains and losses, as well as other-than-temporary impairments, are recognized in the condensed statement of operations based on the specific identification method.
	The Company reviews its marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairment of marketable securities are recognized in the condensed statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable securities, or if it is more likely than not that the Company will be required to sell the marketable securities before recovery of the amortized cost basis.
	Concentrations of credit risk and off-balance sheet risk
	Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents and marketable securities. The Company’s cash, cash equivalents and marketable securities are held in accounts with a financial institution that management believes is creditworthy. The Company’s investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. These amounts at times may exceed federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no financial instruments with off-balance sheet risk of loss.
	Deferred public offering costs
	At March 31, 2015, the Company had $131 thousand of deferred offering costs, which primarily consist of direct, incremental legal and accounting fees related to the Registration Statement and the initiation of an ATM equity offering program.
	Fair value of financial instruments
	The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurement and Disclosures, established a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the financial instrument 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 financial instrument and are developed based on the best information available under the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported or disclosed fair value of the financial instruments and is not a measure of the investment credit quality. Fair value measurements are classified and disclosed in one of the following three categories:
		· 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.
	Financial instruments measured at fair value on a recurring basis include cash equivalents and marketable securities (Note 3) and warrants (Note 5).
	An entity may elect to measure many financial instruments and certain other items at fair value at specified election dates. Subsequent unrealized gains and losses on items for which the fair value option has been elected will be reported in net loss. The Company did not elect to measure any additional financial instruments or other items at fair value. The Company is also required to disclose the fair value of financial instruments not carried at fair value. The fair value of the Company’s long-term debt (Note 4) is determined using current applicable rates for similar instruments as of the balance sheet dates and assessment of the credit rating of the Company. The carrying value of the Company’s long-term debt approximates fair value because the Company’s interest rate yield is near current market rates. The Company’s long-term debt is considered a Level 3 liability within the fair value hierarchy.
	There have been no changes to the valuation methods utilized by the Company during the three months ended March 31, 2015 and 2014. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of financial instruments between levels during the three months ended March 31, 2015 and 2014.
	Reverse stock split
	On January 20, 2014, the Board of Directors and stockholders approved a 1-for-11.9 reverse stock split of the Company’s Common Stock, which was effected on January 21, 2014. Stockholders entitled to fractional shares as a result of the reverse stock split received a cash payment in lieu of receiving fractional shares upon the completion of our initial public offering (“IPO”) on February 17, 2014. The Company’s historical share and per share information were retroactively adjusted to give effect to this reverse stock split. Shares of Common Stock underlying outstanding stock option were proportionately reduced and the respective exercise prices proportionately increased. Shares of Common Stock reserved for future issuance were presented on an as converted basis and the financial statements disclose the adjusted conversion ratios.
	Recently adopted accounting pronouncements
	Standard		Description	Date of adoption	Effect on the financial statements or other significant matters
	Standards that are not yet adopted
	ASU 2014-09, Revenue from Contracts with Customers (Topic 606)		The standard will replace existing revenue recognition standards and significantly expand the disclosure requirements for revenue arrangements. It may be adopted either retrospectively or on a modified retrospective basis to new contracts and existing contracts with remaining performance obligations as of the effective date. This ASU is effective for public entities for annual and interim periods beginning after December 15, 2016. Early adoption is not permitted under GAAP.	January 1, 2017	At this time, the Company has not decided on which method it will use to adopt the new standard, nor has it determined the effects of the new guidelines on its results of operations and financial position. For the foreseeable future, the Company’s revenues will be limited to grants received from government agencies or nonprofit organizations. In April 2015, the FASB issued a proposed one year deferral to the effective date of the new standard. If the proposed one year deferral is approved, the standard will become effective for us on January 1, 2018 (the first quarter of our 2018 fiscal year). We are currently evaluating the method of adoption and the impact of this standard on our financial statements.
	ASU No. 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”).		The standard requires a company to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued. This ASU is effective for annual and interim periods ending after December 15, 2016 and earlier application is permitted.	January 1, 2017	The Company is evaluating the effects of the new standard, but does not expect it will have a material impact on its financial conditions, results of operations, or cash flows.
	ASU No. 2015-03 Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”).		The standard requires a company to present debt issuance costs related to a recognized debt liability in the balance sheet as a direct deduction of the carrying value of the debt liability, consistent with the accounting treatment of debt discounts. This new standard is required to be adopted on a retrospective basis, wherein the balance sheet of each individual period presented should be adjusted to reflect the period-specific effects of applying the new guidance. This ASU is effective for public entities for annual and interim periods beginning after December 15, 2015. Early adoption is permitted.	January 1, 2016	As of March 31, 2015 the Company has $92 thousand of unamortized capitalized debt issuance costs that would require reclassification from an asset to a direct deduction of the carrying value of the debt liability under the new standard. The Company is evaluating other possible implications of the new standard in regards to its balance sheet presentation. The standard is not expected to have material impact on the Company’s financial conditions, results of operations, or cash flows.

Cash_cash_equivalents_and_mark

Cash, cash equivalents and marketable securities	3 Months Ended
	Mar. 31, 2015
Cash, cash equivalents and marketable securities
Cash, cash equivalents and marketable securities
	3. Cash, cash equivalents and marketable securities
	As of March 31, 2015 and December 31, 2014, cash, cash equivalents and marketable securities comprised funds in depository, money market accounts and U.S treasury securities.
	The following table presents the cash, cash equivalents and marketable securities carried at fair value in accordance with the hierarchy defined in Note 2 (in thousands):
								Significant
					Quoted prices			other			Significant
					in active			observable			unobservable
					markets			inputs			inputs
		Total			(Level 1)			(Level 2)			(Level 3)
	March 31, 2015
	Cash	$	311		$	311		$	—		$	—
	Money Market funds, included in cash equivalents	57,160			57,160			—			—
	Marketable securities - U.S. treasuries	27,022			27,022			—			—
	Total	$	84,493		$	84,493		$	—		$	—
	December 31, 2014
	Cash	$	1,066		$	1,066		$	—		$	—
	Money Market funds, included in cash equivalents	18,992			18,992			—			—
	Marketable securities - U.S. treasuries	27,021			27,021			—			—
	Total	$	47,079		$	47,079		$	—		$	—
	Cash equivalents and marketable securities have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third party pricing services or other market observable data. The pricing services utilize industry standard valuation models, including both income-based and market-based approaches and observable market inputs to determine value. The Company validates the prices provided by its third party pricing services by reviewing their pricing methods and obtaining market values from other pricing sources. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of March 31, 2015 and December 31, 2014.
	Marketable securities at March 31, 2015 consist of the following (in thousands):
		Contracted		Amortized			Unrealized			Unrealized			Fair Value
		Maturity		Cost			Gains			Losses
	Current
	U.S. Treasuries	76-275 days		$	27,018		$	4		$	—		$	27,022
	Total			$	27,018		$	4		$	—		$	27,022

LongTerm_Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2015
Long-Term Debt
Long-Term Debt
	4.  Long-Term Debt
	On November 20, 2014, the Company entered into a loan and security agreement (the “Loan Agreement”) with Hercules Technology Growth Capital, Inc. (“Hercules”), which provided up to $27.0 million in debt financing in three separate tranches (“2014 Term Loan”). The first tranche of $17.0 million is available through June 30, 2015, of which $12.0 million was drawn down at loan inception. The second tranche of up to $5.0 million may be drawn, at the Company’s option, on or prior to December 15, 2015, subject to the Company receiving favorable data from its ongoing GEN-003 Phase 2 dose optimization trial and either (i) the commencement of the Company’s next clinical trial for GEN-003 or (ii) the receipt of at least $40.0 million in net proceeds from an equity financing and/or a strategic corporate partnership. In March 2015, the Company satisfied the equity financing condition to the second tranche of the 2014 Term Loan by receiving net proceeds of $48.6 million in its underwritten public offering completed on March 17, 2015. As of March 31, 2015, the Company has not drawn down the second tranche. The third tranche of up to $5.0 million may be drawn, at the Company’s option, on or prior to December 15, 2015, subject to the Company receiving favorable data from its ongoing Phase 2a human challenge study for GEN-004.
	The 2014 Term Loan matures on July 1, 2018. If the eligibility requirements for the second tranche are met, the maturity date may be extended to December 31, 2018 at the Company’s sole election.
	Each advance accrues interest at a floating rate per annum equal to the greater of (i) 7.25% or (ii) the sum of 7.25% plus the prime rate minus 5.0%. The 2014 Term Loan provides for interest-only payments until December 31, 2015, which may be extended at the Company’s sole election for a six month period if the eligibility requirements for the second tranche are met. Thereafter, payments will be made monthly in 30 equal installments of principal and interest (subject to recalculation upon a change in prime rates). The 2014 Term Loan may be prepaid in whole or in part upon seven business days’ prior written notice to Hercules.  Prepayments will be subject to a charge of 3.0% if an advance is prepaid within twelve months following the closing date, 2.0%, if an advance is prepaid between twelve months and twenty four months following the closing date, and 1.0% thereafter. Amounts outstanding during an event of default shall be payable on demand and shall accrue interest at an additional rate of 5.0% per annum on any outstanding amounts past due. The Company must also pay an end of term charge of 4.95% of the balance drawn when the advances are repaid.
	The 2014 Term Loan is secured by a lien on substantially all of the assets of the Company, other than intellectual property, provided that such lien on substantially all assets includes any rights to payments and proceeds from the sale, licensing or disposition of intellectual property.  The Loan Agreement contains non-financial covenants and representations, including a financial reporting covenant, and limitations on dividends, indebtedness, collateral, investments, distributions, transfers, mergers or acquisitions, taxes, corporate changes, deposit accounts, and subsidiaries. There are no financial covenants.
	The Loan Agreement contains a provision that requires all occurrences that would reasonably be expected to have a material adverse effect (“Material Adverse Effect”) to be reported under the financial reporting covenant. Loan advances are subject to a representation that no event that has had or could reasonably be expected to have a Material Adverse Effect has occurred and is continuing. Under the Loan Agreement, a Material Adverse Effect means a material adverse effect upon: (i) the business, operations, properties, assets or condition (financial or otherwise) of the Company; (ii) the ability of the Company to perform the secured obligations in accordance with the terms of the loan documents, or the ability of the agent or lender to enforce any of its rights or remedies with respect to the secured obligations; or (iii) the collateral or the agent’s liens on the collateral or the priority of such liens. Any event that would reasonably be expected to have a Material Adverse Effect is an event of default under the Loan Agreement and, as such, payment of all or any part of the secured obligations may be accelerated upon and during the continuation of such event.
	Events of default under the Loan Agreement include failure to make any payments of principal or interest as due under the Loan Agreement or any other loan document, breach of any covenant (subject to certain additional conditions relating to cure periods and the Company’s actual knowledge of default), any representations or warranties being false or misleading in any material respect,  insolvency or bankruptcy, any attachment, seizure, levy or judgment on the Company’s assets of at least $100,000, or the occurrence of any default under any agreement or obligation of the Company involving indebtedness in excess of $100,000. If an event of default occurs, repayment of all amounts due under the Loan Agreement may be accelerated by the lender, including the applicable prepayment charge.
	The 2014 Term Loan is automatically accelerated upon a change in control, such that the Company must prepay the outstanding amount of all principal and accrued interest through the prepayment date and any unpaid agent’s and lender’s fees and expenses accrued to the date of the repayment (including the end of term charge) and the applicable prepayment charge. If a change in control occurs, repayment of amounts due under the Loan Agreement may be accelerated by the lender.
	Upon closing the 2014 Term Loan, the Company drew down $12.0 million under the first tranche of the Loan Agreement using approximately $9.8 million of the proceeds to repay all outstanding indebtedness under the Company’s 2013 loan agreement (“2013 Term Loan”).
	In connection with the Loan Agreement, the Company issued a common stock warrant to Hercules on November 20, 2014. The warrant is exercisable for 73,725 shares of the Company’s Common Stock (equal to $607,500 divided by the exercise price of $8.24 per share). The exercise price and the number of shares are subject to adjustment upon a merger event, reclassification of the shares of Common Stock, subdivision or combination of the shares of Common Stock or certain dividends payments. The warrant is exercisable until November 20, 2019 and will be exercised automatically on a net issuance basis if not exercised prior to the expiration date and if the then-current fair market value of one share of Common Stock is greater than the exercise price then in effect. The warrant has been classified as equity for all periods it has been outstanding.
	Contemporaneously with the Loan Agreement, the Company also entered into an equity rights letter agreement on November 20, 2014 (the “Equity Rights Letter Agreement”). Pursuant to the Equity Rights Letter Agreement, the Company issued to Hercules 223,463 shares of the Company’s Common Stock for an aggregate purchase price of approximately $2.0 million at a price per share equal to the closing price of the Company’s Common Stock as reported on The NASDAQ Global Market on November 19, 2014 (the “Initial Equity Investment”).  The shares will be subject to resale limitations and may be resold only pursuant to an effective registration statement or an exemption from registration.
	Additionally, under the Equity Rights Letter Agreement, Hercules has the right to participate in any one or more subsequent private placement equity financings of up to $2.0 million on the same terms and conditions as purchases by the other investors in each subsequent equity financing. The Equity Rights Letter Agreement, and all rights and obligations thereunder, will terminate upon the earlier of (1) such time when Hercules has purchased $2.0 million of subsequent equity financing securities in the aggregate and (2) the later of (a) the repayment of all indebtedness under the Loan Agreement and (b) the expiration or termination of the exercise period for the warrant issued in connection with the Loan Agreement. The Company allocated $36 thousand of financing costs to additional paid-in capital for issuance fees that were reimbursed to Hercules.
	In connection with the issuance of the 2014 Term Loan, the Company incurred $103 thousand of debt issuance costs which were recorded in other assets. The Company also reimbursed the lenders $210 thousand for debt financing costs which has been recorded as a debt discount. The 2014 Term Loan included various embedded features which were evaluated for separate accounting as derivatives under ASC Topic No. 815, “Derivatives and Hedging”. In accordance with Topic No. 815, it was determined that none of these embedded features required separate accounting from the debt host.  The debt discount is being amortized to interest expense over the life of the 2014 Term Loan using the effective interest method.
	At March 31, 2015 and December 31, 2014, the principal amount outstanding under the 2014 Term Loan was $12.0 million. Interest expense related to the 2014 Term Loan, including non-cash interest expense, was $319 thousand and none for the three months ended March 31, 2015 and 2014, respectively.
	At March 31, 2015 and December 31, 2014, there was no principal outstanding borrowings under the 2013 Term Loan. Interest expense related to the 2013 Term Loan, including non-cash interest expense, was none and $234 thousand for the three months ended March 31, 2015 and 2014, respectively.
	Future principal payments on the 2014 Term Loan are as follows (in thousands):
		March 31,
		2015
	2015	$	—
	2016	4,529
	2017	4,876
	2018	2,595
	Total	$	12,000

Warrants

Warrants	3 Months Ended
	Mar. 31, 2015
Warrants.
Warrants
	5. Warrants
	At March 31, 2015 and December 31, 2014, the Company had warrants outstanding that represent the right to acquire 77,603 shares of Common Stock, of which 73,725 represented warrants issued to Hercules and 3,878 represent warrants to purchase redeemable securities that were automatically converted to warrants exercisable into Common Stock upon the completion of our IPO on February 10, 2014.
	Hercules warrants
	In accordance with ASC Topic No. 815, “Derivatives and Hedging”, the Company determined the common stock warrant issued to Hercules to be equity classified. The Company estimated the fair value of this warrant as of the issuance date using a Black-Scholes option pricing model (with a 10% discount for lack of marketability) with the following assumptions:
		November 20,
		2014
	Fair value of underlying instrument	$	9.05
	Expected volatility	70.0		%
	Expected term (in years)	5.00
	Risk-free interest rate	1.64		%
	Expected dividend yield	0.0		%
	The Company utilized this fair value in its allocation of debt proceeds between debt and the warrants which was performed on a relative fair value basis. Ultimately, the Company allocated $334 thousand to the Hercules warrants and recognized this amount in additional paid-in capital during the year ended December 31, 2014.
	At March 31, 2015, all of the common stock warrants issued to Hercules remained outstanding.
	Warrants to purchase redeemable securities
	As of December 31, 2013, the Company had outstanding warrants to purchase 2,291,512 shares of redeemable convertible preferred stock. On January 29, 2014, 21,695 warrants to purchase Series A preferred stock were exercised for cash. On February 4, 2014, an additional 28,926 warrants to purchase Series A preferred stock were exercised for cash. Prior to the completion of our IPO on February 10, 2014, warrants to purchase 987,840 shares of Series A preferred stock were exercised in a cashless exercise for 316,932 shares of Series A preferred stock, which automatically converted into 26,633 shares of Common Stock upon the completion of our IPO. Also upon the completion of our IPO, warrants exercisable for 1,253,051 shares of redeemable convertible preferred stock were automatically converted into warrants exercisable for 105,297 shares of Common Stock. On February 12, 2014, 43,465 warrants were exercised in a cashless exercise for 16,593 shares of Common Stock. On April 23, 2014, 57,954 warrants were exercised in a cashless exercise for 37,250 shares of Common Stock. As of March 31, 2015 and December 31, 2014 3,878 of these common stock warrants remained outstanding.

Commitments_and_contingencies

Commitments and contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and contingencies
Commitments and contingencies
	6. Commitments and contingencies
	Significant contracts and agreements
	In August 2006, the Company entered into an agreement to license certain intellectual property from The Regents of the University of California. The agreement calls for payments to be made by the Company upon the occurrence of certain development milestones and certain commercialization milestones for each distinct product covered by the licensed patents, in addition to certain royalties to be paid on marketed products or sublicense income. The Company did not incur any expenses under this agreement for the three months ended March 31, 2015, and 2014.
	In November 2007, the Company entered into an agreement to license certain intellectual property from Harvard University. The agreement calls for payments to be made by the Company upon the occurrence of certain development and regulatory milestones, in addition to certain royalties on marketed products or sublicense income. In addition, the Company must make annual maintenance fee payments, which vary depending on the type of products under development. The Company did not incur any expenses under this agreement for the three months ended March 31, 2015 and 2014, respectively. The Company notified the President and Fellows of Harvard College of its partial termination of the license agreement with regard to the intellectual property covering chlamydia antigens on December 8, 2014. Effective March 8, 2015, the license agreement with the President and Fellows of Harvard College with regard to the intellectual property covering chlamydia antigens has been terminated. The Company determined that the chlamydia antigens were not relevant to the continued development of GEN-001. The Company will continue to maintain exclusive rights to aspects of the ATLAS platform covered by Harvard University intellectual property.
	In August 2009, the Company entered into an agreement to license certain intellectual property from Isconova AB, now Novavax. The agreement calls for payments to be made by the Company upon the occurrence of certain development and commercial milestones, in addition to certain royalties to be paid on marketed products or sublicense income. The Company incurred expenses of $12 thousand and none related to services provided by Novavax for the three months ended March 31, 2015 and 2014, respectively.
	In March 2014, the Company announced a joint research collaboration with Dana-Farber Cancer Institute and Harvard Medical School to characterize anti-tumor T cell responses in melanoma patients. This collaboration extends the use of our proprietary ATLAS platform for the rapid discovery of T cell antigens to cancer immunotherapy approaches. The Company recognized revenue of $21 thousand and none under the agreement for the three months ended March 31, 2015 and 2014, respectively.
	In September 2014, the Company received $1.2 million in the form of a grant entered into with the Bill & Melinda Gates Foundation for the identification of protective T cell antigens for malaria vaccines. The grant will allow for the continued expansion of the Company’s malaria antigen library and aid in the identification of novel protein antigens to facilitate the development of highly efficacious anti-infection malarial vaccines. The Company recognized revenue of $100 thousand and none under the agreement for the three months ended March 31, 2015 and 2014, respectively.
	Supply agreements
	In August 2009, the Company entered into a supply agreement with a third party for the manufacture and supply of antigens used in the Company’s product candidates. The agreement calls for payments to be made by the Company upon the occurrence of certain manufacturing milestones, in addition to reimbursement of certain consumables. In June 2013, the Company entered into another supply agreement with the same vendor for the manufacture and supply of antigens to be used in the Company’s next clinical trials. The Company incurred expenses of $57 thousand and $613 thousand related to these agreements for the three months ended March 31, 2015 and 2014, respectively.
	In February 2014, the Company entered into a supply agreement with FUJIFILM Diosynth Biotechnologies U.S.A., Inc. (“Fujifilm”) for the manufacture and supply of antigens for future GEN-003 clinical trials. Under the agreement, the Company is obligated to pay Fujifilm manufacturing milestones, in addition to reimbursement of certain material production related costs. Additionally, the Company is responsible for the payment of a reservation fee, which will equal a percentage of the expected production fees, to reserve manufacturing slots in the production timeframe.  The Company incurred expenses of $2.5 million and $25 thousand, under this agreement for the three months ended March 31, 2015 and 2014, respectively.
	In October 2014, the Company entered a product development and clinical supply agreement with Baxter Pharmaceutical Solutions LLC (“Baxter”). The product development and clinical supply agreement provides the terms and conditions under which Baxter will formulate, fill, inspect, package, label and test our lead product, GEN-003 for clinical supply. The Company is obligated to pay Baxter for each batch of GEN-003 manufactured. Additionally, certain set-up fees and equipment purchased for the purposes of batch production will be invoiced separately by Baxter. The Company is also responsible for the payment of a monthly service fee for project management services for the duration of the arrangement. The Company incurred expenses of $32 thousand, under this agreement for the three months ended March 31, 2015.
	Restricted cash related to facilities lease
	In February 2014, the Company signed an operating lease for office and laboratory space that commenced in March 2014 and expires in February 2017 (“2012 Master Facilities Lease”). At March 31, 2015 and December 31, 2014, the Company had $316 thousand of restricted cash related to the 2012 Master Facilities Lease.
	At March 31, 2015, the Company has an outstanding letter of credit with a financial institution related to a security deposit for the 2012 Master Facilities Lease, which is secured by cash on deposit and expires on February 28, 2017.
	Litigation
	The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities.

Common_stock

Common stock	3 Months Ended
	Mar. 31, 2015
Common stock.
Common stock
	7. Common stock
	At March 31, 2015, the Company had authorized 175,000,000 shares of Common Stock, $0.001 par value per share, of which 24,152,291 shares were issued and 24,137,395 were outstanding.
	Restricted stock
	During 2013, a director of the Company early exercised stock options and received 31,092 shares of Common Stock that were subject to a Stock Restriction and Repurchase Agreement with the Company. Under the terms of the agreement, shares of Common Stock issued are subject to a vesting schedule. Vesting occurs periodically at specified time intervals and specified percentages. All shares of Common Stock become fully vested within four years of the date of grant. As of December 31, 2014, the Company had 16,840 shares of nonvested restricted stock that were subject to repurchase by the Company. As of March 31, 2015, the Company has issued 35,964 shares of restricted common stock of which 21,068 shares have vested and 14,896 shares are subject to repurchase by the Company.
	Reserve for future issuance
	The Company has reserved for future issuances the following number of shares of Common Stock (in thousands):
		March 31,	December 31,
		2015	2014
	Options to purchase Common Stock	3,077	2,373
	Options to purchase Common Stock under Employee Stock Purchase Plan (“ESPP”)	185	185
	Warrants to purchase Common Stock	78	78
		3,340	2,636

Stockbased_compensation

Stock-based compensation	3 Months Ended
	Mar. 31, 2015
Stock-based compensation
Stock-based compensation
	8. Stock-based compensation
	The Company’s Board of Directors adopted the 2014 Equity Incentive Plan (the “2014 Equity Plan”), which was approved by its stockholders and became effective prior to the commencement of our IPO on February 10, 2014. The 2014 Equity Plan replaced the 2007 Equity Incentive Plan (the “2007 Equity Plan”).
	The 2014 Equity Plan provided for the grant of incentive stock options, non-qualified stock options and restricted stock awards to key employees and directors of, and consultants and advisors to, the Company. The maximum number of shares of Common Stock that may be delivered in satisfaction of awards under the 2014 Equity Plan is 903,494 shares, plus 219,765 shares that were available for grant under the 2007 Equity Plan on the date the 2014 Equity Plan was adopted. The 2014 Equity Plan provides that the number of shares available for issuance will automatically increase annually on each January 1, from January 1, 2015 through January 1, 2024, in amount equal to the lesser of 4.0% of the outstanding shares of the Company’s outstanding Common Stock as of the close of business on the immediately preceding December 31 or the number of shares determined the Company’s Board of Directors. On January 1, 2015, the shares available under the 2014 Equity Plan increased by 714,769 shares of Common Stock.
	Outstanding options awards granted from the 2007 Equity Plan, at the time of the adoption of the 2014 Equity Plan, remain outstanding and effective. The shares of Common Stock underlying awards that are cancelled, forfeited, repurchased, expire or are otherwise terminated under the 2014 Equity Plan are added to the shares of Common Stock available for issuance under the 2014 Equity Plan. As of March 31, 2015, the number of common shares that may be issued under both equity plans is 3,076,820 and 313,692 remain available for future grants.
	Stock Based Compensation Expense
	Total stock-based compensation expense is recognized for stock options granted to employees and non-employees and has been reported in the Company’s statements of operations as follows (in thousands):
		Three months ended March 31,
		2015			2014
	Research and development	$	415		$	477
	General and administrative	500			404
	Total	$	915		$	881
	Stock Options
	The following table summarizes stock option activity for employees and nonemployees (shares in thousands):
							Weighted-
				Weighted-			Average
				Average			Remaining	Aggregate
				Exercise			Contractual	Intrinsic
		Shares		Price			Term (years)	Value
	Outstanding at December 31, 2014	2,290		$	7.26		8.08	$	5,332
	Granted	533		$	9.08
	Exercised	(10	)	$	2.5
	Canceled	(50	)	$	15.49
	Outstanding at March 31, 2015	2,763		$	7.48		8.05	$	13,755
	Exercisable at March 31, 2015	1,130		$	3.77		6.38	$	9,220
	Vested or expected to vest at March 31, 2015	2,596		$	7.36		7.99	$	13,224
	Performance-Based Stock Options
	The Company granted stock options to certain employees, executive officers and consultants, which contain performance-based vesting criteria. Milestone events are specific to the Company’s corporate goals, which include, but are not limited to, certain clinical development milestones, business development agreements and capital fundraising events. Stock-based compensation expense associated with these performance-based stock options is recognized if the performance conditions are considered probable of being achieved, using management’s best estimates. During the three months ended March 31, 2015 and 2014, the Company determined that none and 96,988 performance-based milestones, respectively, were probable of achievement and, accordingly, recorded none and $435 thousand in related stock-based compensation expense during the three months ended March 31, 2015 and 2014, respectively. As of March 31, 2015, there are 56,336 performance-based common stock options outstanding for which the probability of achievement was not deemed probable.
	Employee Stock Purchase Plan
	In connection with the completion of our IPO on February 10, 2014, the Company’s Board of Directors adopted the 2014 Employee Stock Purchase Plan (the “2014 ESPP”). The 2014 ESPP authorizes the initial issuance of up to a total of 200,776 shares of Common Stock to participating eligible employees. The 2014 ESPP provides for six-month option periods commencing on January 1 and ending June 30 and commencing July 1 and ending December 31 of each calendar year. The first offering under the 2014 ESPP began on July 1, 2014. During the year ended December 31, 2014, 15,622 shares were issued under the 2014 ESPP with 185,154 shares remaining for future issuance under the plan as of March 31, 2015. The second offering under the 2014 ESPP began on January 1, 2015. The Company incurred $26 thousand in stock-based compensation expense related to the 2014 ESPP for the three months ended March 31, 2015.

Income_taxes

Income taxes	3 Months Ended
	Mar. 31, 2015
Income taxes
Income taxes
	9. Income taxes
	Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. Based on the Company’s history of operating losses, the Company has concluded that it is more likely than not that the benefit of its deferred tax assets will not be realized. There were no significant income tax provisions or benefits for the three months ended March 31, 2015 and 2014. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has provided a full valuation allowance against its deferred tax assets.

Net_loss_per_share_attributabl

Net loss per share attributable to common stockholders	3 Months Ended
	Mar. 31, 2015
Net loss per share attributable to common stockholders
Net loss per share attributable to common stockholders
	10. Net loss per share attributable to common stockholders
	The Company computes basic and diluted earnings (loss) per share using a methodology that gives effect to the impact of outstanding participating securities (the “two-class method”). As the three month periods ended March 31, 2015 and 2014 resulted in net losses, there is no income allocation required under the two-class method or dilution attributed to weighted average shares outstanding in the calculation of diluted loss per share.
	The following common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect (in thousands):
		Three months ended March 31,
		2015	2014
	Warrants	78	62
	Outstanding options	2,763	2,003
	Outstanding ESPP	11	—
	Total	2,852	2,065

Subsequent_events

Subsequent events	3 Months Ended
	Mar. 31, 2015
Subsequent events
Subsequent events
	11. Subsequent events
	The Company has evaluated all activity that occurred subsequent to quarter end but prior to issuance of the condensed financial statements for events or transactions that could require disclosure or that could impact the carrying value of assets or liabilities as of the balance sheet date. In the judgment of management, there were no material events that impacted the unaudited condensed financial statements or disclosures.

Summary_of_significant_account1

Summary of significant accounting policies (Policies)	3 Months Ended
	Mar. 31, 2015
Summary of significant accounting policies
Basis of presentation
	The accompanying condensed financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. These interim condensed financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended March 31, 2015 and 2014.
	The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full fiscal year. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2014 and the notes thereto which are included in the Company’s Annual Report on Form 10-K, as filed with the SEC on February 27, 2015.
Use of estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, estimates related to prepaid and accrued research and development expenses, stock-based compensation expense, the valuation of common stock warrants and warrants to purchase redeemable securities, and reported amounts of revenues and expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Cash and cash equivalents
	The Company considers all highly liquid investments with maturities of 90 days or less from the purchase date to be cash equivalents. Cash and cash equivalents are held in depository and money market accounts and are reported at fair value.
Marketable securities
	Marketable securities consist of U.S. treasury securities with maturities of more than 90 days. The Company has determined the appropriate balance sheet classification of the securities as current since they are available for use in current operating activities, regardless of actual maturity dates. Marketable securities are classified as available-for-sale pursuant to FASB ASC Topic 320, Investments — Debt and Equity Securities,(“ASC 320”) and are recorded on the balance sheet at fair value with unrealized gains and losses (excluding other-than-temporary impairments) reported as a separate component of accumulated other comprehensive income (loss). Realized gains and losses, as well as other-than-temporary impairments, are recognized in the condensed statement of operations based on the specific identification method.
	The Company reviews its marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairment of marketable securities are recognized in the condensed statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable securities, or if it is more likely than not that the Company will be required to sell the marketable securities before recovery of the amortized cost basis.
Concentrations of credit risk and off-balance sheet risk
	Concentrations of credit risk and off-balance sheet risk
	Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents and marketable securities. The Company’s cash, cash equivalents and marketable securities are held in accounts with a financial institution that management believes is creditworthy. The Company’s investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. These amounts at times may exceed federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no financial instruments with off-balance sheet risk of loss.
Deferred public offering costs
	Deferred public offering costs
	At March 31, 2015, the Company had $131 thousand of deferred offering costs, which primarily consist of direct, incremental legal and accounting fees related to the Registration Statement and the initiation of an ATM equity offering program.
Fair value of financial instruments
	Fair value of financial instruments
	The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurement and Disclosures, established a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the financial instrument 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 financial instrument and are developed based on the best information available under the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported or disclosed fair value of the financial instruments and is not a measure of the investment credit quality. Fair value measurements are classified and disclosed in one of the following three categories:
		· 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.
	Financial instruments measured at fair value on a recurring basis include cash equivalents and marketable securities (Note 3) and warrants (Note 5).
	An entity may elect to measure many financial instruments and certain other items at fair value at specified election dates. Subsequent unrealized gains and losses on items for which the fair value option has been elected will be reported in net loss. The Company did not elect to measure any additional financial instruments or other items at fair value. The Company is also required to disclose the fair value of financial instruments not carried at fair value. The fair value of the Company’s long-term debt (Note 4) is determined using current applicable rates for similar instruments as of the balance sheet dates and assessment of the credit rating of the Company. The carrying value of the Company’s long-term debt approximates fair value because the Company’s interest rate yield is near current market rates. The Company’s long-term debt is considered a Level 3 liability within the fair value hierarchy.
	There have been no changes to the valuation methods utilized by the Company during the three months ended March 31, 2015 and 2014. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of financial instruments between levels during the three months ended March 31, 2015 and 2014.
Reverse stock split
	Reverse stock split
	On January 20, 2014, the Board of Directors and stockholders approved a 1-for-11.9 reverse stock split of the Company’s Common Stock, which was effected on January 21, 2014. Stockholders entitled to fractional shares as a result of the reverse stock split received a cash payment in lieu of receiving fractional shares upon the completion of our initial public offering (“IPO”) on February 17, 2014. The Company’s historical share and per share information were retroactively adjusted to give effect to this reverse stock split. Shares of Common Stock underlying outstanding stock option were proportionately reduced and the respective exercise prices proportionately increased. Shares of Common Stock reserved for future issuance were presented on an as converted basis and the financial statements disclose the adjusted conversion ratios.
Recently adopted accounting pronouncements
	Recently adopted accounting pronouncements
	Standard		Description	Date of adoption	Effect on the financial statements or other significant matters
	Standards that are not yet adopted
	ASU 2014-09, Revenue from Contracts with Customers (Topic 606)		The standard will replace existing revenue recognition standards and significantly expand the disclosure requirements for revenue arrangements. It may be adopted either retrospectively or on a modified retrospective basis to new contracts and existing contracts with remaining performance obligations as of the effective date. This ASU is effective for public entities for annual and interim periods beginning after December 15, 2016. Early adoption is not permitted under GAAP.	January 1, 2017	At this time, the Company has not decided on which method it will use to adopt the new standard, nor has it determined the effects of the new guidelines on its results of operations and financial position. For the foreseeable future, the Company’s revenues will be limited to grants received from government agencies or nonprofit organizations. In April 2015, the FASB issued a proposed one year deferral to the effective date of the new standard. If the proposed one year deferral is approved, the standard will become effective for us on January 1, 2018 (the first quarter of our 2018 fiscal year). We are currently evaluating the method of adoption and the impact of this standard on our financial statements.
	ASU No. 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”).		The standard requires a company to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued. This ASU is effective for annual and interim periods ending after December 15, 2016 and earlier application is permitted.	January 1, 2017	The Company is evaluating the effects of the new standard, but does not expect it will have a material impact on its financial conditions, results of operations, or cash flows.
	ASU No. 2015-03 Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”).		The standard requires a company to present debt issuance costs related to a recognized debt liability in the balance sheet as a direct deduction of the carrying value of the debt liability, consistent with the accounting treatment of debt discounts. This new standard is required to be adopted on a retrospective basis, wherein the balance sheet of each individual period presented should be adjusted to reflect the period-specific effects of applying the new guidance. This ASU is effective for public entities for annual and interim periods beginning after December 15, 2015. Early adoption is permitted.	January 1, 2016	As of March 31, 2015 the Company has $92 thousand of unamortized capitalized debt issuance costs that would require reclassification from an asset to a direct deduction of the carrying value of the debt liability under the new standard. The Company is evaluating other possible implications of the new standard in regards to its balance sheet presentation. The standard is not expected to have material impact on the Company’s financial conditions, results of operations, or cash flows.

Summary_of_significant_account2

Summary of significant accounting policies (Tables)	3 Months Ended
	Mar. 31, 2015
Summary of significant accounting policies
Schedule of recent accounting pronouncements
	Standard	Description	Date of adoption	Effect on the financial statements or other significant matters
	Standards that are not yet adopted
	ASU 2014-09, Revenue from Contracts with Customers (Topic 606)	The standard will replace existing revenue recognition standards and significantly expand the disclosure requirements for revenue arrangements. It may be adopted either retrospectively or on a modified retrospective basis to new contracts and existing contracts with remaining performance obligations as of the effective date. This ASU is effective for public entities for annual and interim periods beginning after December 15, 2016. Early adoption is not permitted under GAAP.	January 1, 2017	At this time, the Company has not decided on which method it will use to adopt the new standard, nor has it determined the effects of the new guidelines on its results of operations and financial position. For the foreseeable future, the Company’s revenues will be limited to grants received from government agencies or nonprofit organizations. In April 2015, the FASB issued a proposed one year deferral to the effective date of the new standard. If the proposed one year deferral is approved, the standard will become effective for us on January 1, 2018 (the first quarter of our 2018 fiscal year). We are currently evaluating the method of adoption and the impact of this standard on our financial statements.
	ASU No. 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”).	The standard requires a company to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued. This ASU is effective for annual and interim periods ending after December 15, 2016 and earlier application is permitted.	January 1, 2017	The Company is evaluating the effects of the new standard, but does not expect it will have a material impact on its financial conditions, results of operations, or cash flows.
	ASU No. 2015-03 Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”).	The standard requires a company to present debt issuance costs related to a recognized debt liability in the balance sheet as a direct deduction of the carrying value of the debt liability, consistent with the accounting treatment of debt discounts. This new standard is required to be adopted on a retrospective basis, wherein the balance sheet of each individual period presented should be adjusted to reflect the period-specific effects of applying the new guidance. This ASU is effective for public entities for annual and interim periods beginning after December 15, 2015. Early adoption is permitted.	January 1, 2016	As of March 31, 2015 the Company has $92 thousand of unamortized capitalized debt issuance costs that would require reclassification from an asset to a direct deduction of the carrying value of the debt liability under the new standard. The Company is evaluating other possible implications of the new standard in regards to its balance sheet presentation. The standard is not expected to have material impact on the Company’s financial conditions, results of operations, or cash flows.

Cash_and_cash_equivalents_and_

Cash and cash equivalents and marketable securities (Tables)	3 Months Ended
	Mar. 31, 2015
Cash, cash equivalents and marketable securities
Schedule of cash, cash equivalents and marketable securities carried at fair value
	The following table presents the cash, cash equivalents and marketable securities carried at fair value in accordance with the hierarchy defined in Note 2 (in thousands):
								Significant
					Quoted prices			other			Significant
					in active			observable			unobservable
					markets			inputs			inputs
		Total			(Level 1)			(Level 2)			(Level 3)
	March 31, 2015
	Cash	$	311		$	311		$	—		$	—
	Money Market funds, included in cash equivalents	57,160			57,160			—			—
	Marketable securities - U.S. treasuries	27,022			27,022			—			—
	Total	$	84,493		$	84,493		$	—		$	—
	December 31, 2014
	Cash	$	1,066		$	1,066		$	—		$	—
	Money Market funds, included in cash equivalents	18,992			18,992			—			—
	Marketable securities - U.S. treasuries	27,021			27,021			—			—
	Total	$	47,079		$	47,079		$	—		$	—
Schedule of marketable securities
	Marketable securities at March 31, 2015 consist of the following (in thousands):
		Contracted		Amortized			Unrealized			Unrealized			Fair Value
		Maturity		Cost			Gains			Losses
	Current
	U.S. Treasuries	76-275 days		$	27,018		$	4		$	—		$	27,022
	Total			$	27,018		$	4		$	—		$	27,022

LongTerm_Debt_Tables

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Long-Term Debt
Schedule of future principal payments on the new term loan
	Future principal payments on the 2014 Term Loan are as follows (in thousands):
		March 31,
		2015
	2015	$	—
	2016	4,529
	2017	4,876
	2018	2,595
	Total	$	12,000

Warrants_Tables

Warrants (Tables)	3 Months Ended
	Mar. 31, 2015
Warrants.
Schedule of weighted average assumptions used to calculate the fair value of warrants
		November 20,
		2014
	Fair value of underlying instrument	$	9.05
	Expected volatility	70.0		%
	Expected term (in years)	5.00
	Risk-free interest rate	1.64		%
	Expected dividend yield	0.0		%

Common_stock_Tables

Common stock (Tables)	3 Months Ended
	Mar. 31, 2015
Common stock.
Schedule of shares of common stock reserved for future issuance
	The Company has reserved for future issuances the following number of shares of Common Stock (in thousands):
		March 31,	December 31,
		2015	2014
	Options to purchase Common Stock	3,077	2,373
	Options to purchase Common Stock under Employee Stock Purchase Plan (“ESPP”)	185	185
	Warrants to purchase Common Stock	78	78
		3,340	2,636

Stockbased_compensation_Tables

Stock-based compensation (Tables)	3 Months Ended
	Mar. 31, 2015
Stock-based compensation
Schedule of stock-based compensation expense for stock options granted to employees and non-employees
	Total stock-based compensation expense is recognized for stock options granted to employees and non-employees and has been reported in the Company’s statements of operations as follows (in thousands):
		Three months ended March 31,
		2015			2014
	Research and development	$	415		$	477
	General and administrative	500			404
	Total	$	915		$	881
Schedule of stock option activity for employees and nonemployees
	The following table summarizes stock option activity for employees and nonemployees (shares in thousands):
							Weighted-
				Weighted-			Average
				Average			Remaining	Aggregate
				Exercise			Contractual	Intrinsic
		Shares		Price			Term (years)	Value
	Outstanding at December 31, 2014	2,290		$	7.26		8.08	$	5,332
	Granted	533		$	9.08
	Exercised	(10	)	$	2.5
	Canceled	(50	)	$	15.49
	Outstanding at March 31, 2015	2,763		$	7.48		8.05	$	13,755
	Exercisable at March 31, 2015	1,130		$	3.77		6.38	$	9,220
	Vested or expected to vest at March 31, 2015	2,596		$	7.36		7.99	$	13,224

Net_loss_per_share_attributabl1

Net loss per share attributable to common stockholders (Tables)	3 Months Ended
	Mar. 31, 2015
Net loss per share attributable to common stockholders
Schedule of common stock equivalents, presented on converted basis, were excluded from calculation of net loss per share due to anti-dilutive effect
	The following common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect (in thousands):
		Three months ended March 31,
		2015	2014
	Warrants	78	62
	Outstanding options	2,763	2,003
	Outstanding ESPP	11	—
	Total	2,852	2,065

Organization_and_operations_De

Organization and operations (Details)	3 Months Ended
	Mar. 31, 2015
	item
Organization and operations
Number of products in clinical development	2

Organization_and_operations_De1

Organization and operations (Details 2) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Mar. 17, 2015	Dec. 31, 2014
Underwritten public offering
Common stock, par value (in dollars per share)	$0.00		$0.00
Proceeds from sale of common stock, net of issuance costs	$48,367,000
At-the-market equity offering program, maximum value of common stock to offer and sale	40,000,000
Underwritten public offering
Underwritten public offering
Common stock, par value (in dollars per share)		$0.00
Issuance of common stock (in shares)		6,272,726
Share price		$8.25
Proceeds from sale of common stock, net of issuance costs		48,600,000
Offering expenses		$276,000
Over-allotment option
Underwritten public offering
Issuance of common stock (in shares)		818,181

Summary_of_significant_account3

Summary of significant accounting policies (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
	item
Cash, cash equivalents and marketable securities
Maximum maturity period for a highly liquid investment to be considered cash and cash equivalents	90 days
Concentrations of credit risk and off-balance sheet risk
Number of financial instruments with off-balance sheet risk of loss	0
Fair value of financial instruments
Transfers of financial assets between levels	$0
Transfers of financial liabilities between levels	$0

Summary_of_significant_account4

Summary of significant accounting policies (Details 2) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Deferred public offering costs
Deferred offering costs	$131

Summary_of_significant_account5

Summary of significant accounting policies (Details 3)	0 Months Ended
	Jan. 20, 2014
Reverse stock split
Reverse stock split ratio	0.084034

Cash_and_cash_equivalents_and_1

Cash and cash equivalents and marketable securities (Details) (Recurring, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Quoted prices in active markets (Level 1)
Cash, cash equivalents and marketable securities
Cash	$311	$1,066
Money Market funds, included in cash equivalents	57,160	18,992
Total	84,493	47,079
Quoted prices in active markets (Level 1) | U.S. Treasuries
Cash, cash equivalents and marketable securities
Marketable securities - U.S. treasuries	27,022	27,021
Total
Cash, cash equivalents and marketable securities
Cash	311	1,066
Money Market funds, included in cash equivalents	57,160	18,992
Total	84,493	47,079
Total | U.S. Treasuries
Cash, cash equivalents and marketable securities
Marketable securities - U.S. treasuries	$27,022	$27,021

Cash_and_cash_equivalents_and_2

Cash and cash equivalents and marketable securities (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Marketable securities
Fair Value, Total	$27,022	$27,021
U.S. Treasuries
Marketable securities
U.S. Treasuries (due 76-275 days) Amortized Cost	27,018
U.S. Treasuries (due 76-275 days) Unrealized Gains	4
U.S. Treasuries (due 76-275 days) Fair Value	27,022
Amortized Cost, Total	27,018
Unrealized Gains, Total	4
Fair Value, Total	$27,022
U.S. Treasuries | Minimum
Marketable securities
Contracted Maturity - U.S. Treasuries (due 76-275 days)	76 days
U.S. Treasuries | Maximum
Marketable securities
Contracted Maturity - U.S. Treasuries (due 76-275 days)	275 days

Longterm_debt_Details

Long-term debt (Details) (USD $)	3 Months Ended	0 Months Ended	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Nov. 20, 2014	Mar. 31, 2014	Mar. 17, 2015	Dec. 31, 2014
Long-Term Debt
Proceeds from sale of common stock, net of issuance costs	$48,367,000
Common stock
Long-Term Debt
Exercisable amount (in shares)	77,603
Line of Credit | 2013 Term Loan
Long-Term Debt
Repay indebtedness		9,800,000
Outstanding borrowings	0				0
Interest expense	0		234,000
Line of Credit | 2014 Term Loan
Long-Term Debt
Debt financing		27,000,000
Tranches, number		3
Draw downs		12,000,000
Interest rate (as a percent)		7.25%
Extended term		6 months
Number of monthly payments of principal and accrued interest		30
Prepayment, written notice period		7 days
Prepayment charge, first twelve months (as a percent)		3.00%
Prepayment charge, between twelve months and twenty four months (as a percent)		2.00%
Prepayment charge, after twenty four months (as a percent)		1.00%
Additional interest rate (as a percent)		5.00%
End of term charge (as a percent)		4.95%
Attachment or judgment on the Company's assets causing an event of default, minimum		100,000
Default of the Company's involving indebtedness causing an event of default, minimum		100,000
Debt discount		210,000
Outstanding borrowings	12,000,000				12,000,000
Interest expense	319,000		0
Line of Credit | 2014 Term Loan | Other current assets
Long-Term Debt
Financing costs		103,000
Line of Credit | 2014 Term Loan | Prime rate
Long-Term Debt
Variable rate basis (as a percent)		7.25%
Spread on variable rate basis (as a percent)		-5.00%
Line of Credit | 2014 Term Loan, First Tranche
Long-Term Debt
Debt financing		17,000,000
Draw downs		12,000,000
Line of Credit | 2014 Term Loan, Second Tranche
Long-Term Debt
Debt financing		5,000,000
Net proceeds from an equity financing and/or strategic corporate partnership, minimum		40,000,000
Line of Credit | 2014 Term Loan, Third Tranche
Long-Term Debt
Debt financing		5,000,000
Hercules Technology Growth Capital, Inc. | Common stock
Long-Term Debt
Exercisable amount (in shares)	73,725	73,725
Warrant, exercisable, value		607,500
Exercise price of warrant (in dollars per share)		$8.24
Expected term		5 years
Underwritten public offering
Long-Term Debt
Proceeds from sale of common stock, net of issuance costs				48,600,000
Issuance of common stock (in shares)				6,272,726
Financing costs allocated to additional paid-in capital				276,000
Private Placement | Hercules Technology Growth Capital, Inc.
Long-Term Debt
Issuance of common stock (in shares)		223,463
Issuance of common stock		2,000,000
Subsequent private placement equity financings, amount		2,000,000
Financing costs allocated to additional paid-in capital		$36,000

Longterm_debt_Details_2

Long-term debt (Details 2) (2014 Term Loan, Line of Credit, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
2014 Term Loan | Line of Credit
Future principal payments
2016	$4,529
2017	4,876
2018	2,595
Total	$12,000	$12,000

Warrants_Details

Warrants (Details)	Mar. 31, 2015	Dec. 31, 2014	Feb. 10, 2014	Nov. 20, 2014
Common stock
Warrants
Warrants (in shares)	77,603
Warrants to purchase redeemable convertible preferred stock automatically converted to warrants to purchase common stock
Warrants
Warrants (in shares)	3,878	3,878	105,297
Hercules Technology Growth Capital, Inc. | Common stock
Warrants
Warrants (in shares)	73,725			73,725

Warrants_Details_2

Warrants (Details 2) (Hercules Technology Growth Capital, Inc., Common stock, USD $)	0 Months Ended	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Nov. 20, 2014	Dec. 31, 2014
Hercules Technology Growth Capital, Inc. | Common stock
Weighted average assumptions used to calculate the fair value of warrants
Fair value of underlying instrument (in dollars per share)	$9.05
Expected Volatility (as a percent)	70.00%
Expected term	5 years
Risk-free interest rate (as a percent)	1.64%
Expected dividend yield (as a percent)	0.00%
Amount recognized in additional paid-in capital		$334

Warrants_Details_3

Warrants (Details 3)	0 Months Ended
	Jan. 29, 2014	Feb. 04, 2014	Apr. 23, 2014	Feb. 12, 2014	Feb. 10, 2014	Dec. 31, 2013	Mar. 31, 2015	Dec. 31, 2014
Warrants to purchase redeemable convertible preferred stock
Warrants
Warrants (in shares)					1,253,051	2,291,512
Warrants to purchase shares of series A preferred stock exercised, one
Warrants
Warrants exercised (in shares)	21,695
Warrants to purchase shares of series A preferred stock exercised, two
Warrants
Warrants exercised (in shares)		28,926
Warrants to purchase shares of series A preferred stock in cashless exercise
Warrants
Warrants exercised (in shares)			57,954	43,465	987,840
Series A Preferred stock resulting from the cashless exercise of warrants (in shares)					316,932
Common Stock resulting from the automatic conversion of Series A Preferred stock (in shares)			37,250	16,593	26,633
Warrants to purchase redeemable convertible preferred stock automatically converted to warrants to purchase common stock
Warrants
Warrants (in shares)					105,297		3,878	3,878
Common stock
Warrants
Warrants (in shares)							77,603

Commitments_and_contingencies_

Commitments and contingencies (Details) (USD $)	1 Months Ended	3 Months Ended
	Sep. 30, 2014	Mar. 31, 2015	Mar. 31, 2014
Commitments and contingencies
Grant revenue		$121,000
Bill and Melinda Gates Foundation
Commitments and contingencies
Grant received	1,200,000
Grant revenue		100,000	0
Agreement to license certain intellectual property | Novavax
Commitments and contingencies
Expenses incurred		12,000	0
Joint research collaboration agreement | Dana-Farber Cancer Institute and Harvard Medical School
Commitments and contingencies
Grant revenue		$21,000	$0

Commitments_and_contingencies_1

Commitments and contingencies (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Commitments and contingencies
Amount expensed related to supply agreements	$8,509	$4,407
Supply agreement | Third party vendor
Commitments and contingencies
Amount expensed related to supply agreements	57	613
Supply agreement | Fujifilm
Commitments and contingencies
Amount expensed related to supply agreements	2,500	25
Product development and clinical supply agreement | Baxter
Commitments and contingencies
Amount expensed related to supply agreements	$32

Commitments_and_contingencies_2

Commitments and contingencies (Details 3) (2012 Master Facilities Lease, USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
2012 Master Facilities Lease
Restricted cash related to facilities leases
Restricted cash	$316

Common_stock_Details

Common stock (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common stock
Common stock, shares authorized	175,000,000	175,000,000
Common stock, par value (in dollars per share)	0.001	0.001
Common stock, shares issued	24,152,291	17,869,000
Common stock, shares outstanding	24,137,395	17,852,000
Shares of common stock reserved for future issuance
Total common shares reserved for future issuance	3,340,000	2,636,000
Series B redeemable convertible preferred stock | Common stock
Shares of common stock reserved for future issuance
Total common shares reserved for future issuance	78,000	78,000
Outstanding options
Common stock
Options exercised (in shares)	10,000
Outstanding options | Seed convertible preferred stock
Shares of common stock reserved for future issuance
Total common shares reserved for future issuance	3,077,000	2,373,000
Employee stock purchase plan
Shares of common stock reserved for future issuance
Total common shares reserved for future issuance	185,000	185,000
Restricted common stock
Common stock
Vesting period	4 years
Number of shares issued	35,964
Number of shares vested	21,068
Number of shares subject to repurchase by entity	14,896	16,840
Director | Outstanding options
Common stock
Options exercised (in shares)			31,092

Stockbased_compensation_Detail

Stock-based compensation (Details)	0 Months Ended
	Jan. 01, 2015	Mar. 31, 2015	Dec. 31, 2014	Feb. 10, 2014
Stock-based compensation
Common shares that may be issued		3,340,000	2,636,000
2014 Equity Plan
Stock-based compensation
Number of shares authorized		903,494
Increase in shares	714,769
2014 Equity Plan | Maximum
Stock-based compensation
Percentage applied on total number of shares of common stock outstanding on previous calendar year for automatic inclusion in the plan		4.00%
2007 Equity Plan
Stock-based compensation
Number of shares available for grant				219,765
Outstanding options | 2007 Equity Plan and 2014 Equity Plan
Stock-based compensation
Common shares that may be issued		3,076,820
Number of shares available for grant		313,692

Stockbased_compensation_Detail1

Stock-based compensation (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Stock Based Compensation Expense
Stock-based compensation expense	$915	$881
Research and development
Stock Based Compensation Expense
Stock-based compensation expense	415	477
General and administrative
Stock Based Compensation Expense
Stock-based compensation expense	$500	$404

Stockbased_compensation_Detail2

Stock-based compensation (Details 3) (Outstanding options, USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Outstanding options
Shares
Outstanding at the beginning of the period (in shares)	2,290,000
Granted (in shares)	533,000
Exercised (in shares)	-10,000
Canceled (in shares)	-50,000
Outstanding at the end of the period (in shares)	2,763,000	2,290,000
Exercisable at the end of the period (in shares)	1,130,000
Vested or expected to vest at the end of the period (in shares)	2,596,000
Weighted - Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$7.26
Granted (in dollars per share)	$9.08
Exercised (in dollars per share)	$2.50
Canceled (in dollars per share)	$15.49
Outstanding at the end of the period (in dollars per share)	$7.48	$7.26
Exercisable at the end of the period (in dollars per share)	$3.77
Vested or expected to vest at the end of the period (in dollars per share)	$7.36
Weighted- Average Remaining Contractual Term
Outstanding at the end of the period	8 years 18 days	8 years 29 days
Exercisable at the end of the period	6 years 4 months 17 days
Vested or expected to vest at the end of the period	7 years 11 months 27 days
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars )	$13,755	$5,332
Exercisable at the end of the period (in dollars )	9,220
Vested or expected to vest at the end of the period (in dollars )	$13,224

Stockbased_compensation_Detail3

Stock-based compensation (Details 4) (USD $)	3 Months Ended		12 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Additional disclosures
Stock-based compensation expense	$915	$881
Performance-based stock options
Additional disclosures
Number of options probable to achieve performance-based milestones	0	96,988
Stock-based compensation expense	0	435
Options outstanding (in shares)	56,336
Employee stock purchase plan | 2014 ESPP
Additional disclosures
Number of shares of common stock authorized under the plan	200,776
Option period	6 months
Number of shares issued			15,622
Shares remaining for future issuance (in shares)	185,154
Stock-based compensation expense	$26

Net_loss_per_share_attributabl2

Net loss per share attributable to common stockholders (Details)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	2,852	2,065
Warrants
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	78	62
Outstanding options
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	2,763	2,003
Employee stock purchase plan
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	11