Genocea Biosciences (GNCAQ) 10-Q 6 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	May. 04, 2016
Document and Entity Information
Entity Registrant Name	GENOCEA BIOSCIENCES, INC.
Entity Central Index Key	1,457,612
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		28,293,583
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1

Condensed Balance Sheets

Condensed Balance Sheets - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 37,730,000	$ 17,259,000
Investments, current portion	57,926,000	77,069,000
Prepaid expenses and other current assets	1,561,000	865,000
Restricted cash	316,000	0
Restricted cash	97,533,000	95,193,000
Total current assets	4,751,000	4,083,000
Property and equipment, net	0	316,000
Restricted cash	0	12,104,000
Investments, net of current portion	371,000	446,000
Other non-current assets	102,655,000	112,142,000
Liabilities and stockholders’ equity
Current liabilities:	2,151,000	1,757,000
Accounts payable	2,911,000	3,975,000
Accrued expenses and other current liabilities	0	235,000
Other current liabilities	5,062,000	5,967,000
Total current liabilities
Non-current liabilities:	16,592,000	16,477,000
Deferred revenue, net of current portion	11,000	37,000
Other non-current liabilities	$ 21,665,000	$ 22,481,000
Total liabilities
Preferred Stock, Value, Outstanding	$ 0	$ 0
Common Stock, Value, Outstanding	28,000	28,000
Commitments and contingencies (Note 5)
Preferred stock	248,623,000	247,550,000
Accumulated other comprehensive income (loss)	0	(7,000)
Common stock	(167,661,000)	(157,910,000)
Additional paid-in-capital	80,990,000	89,661,000
Accumulated other comprehensive loss	$ 102,655,000	$ 112,142,000

Condensed Statements of Operati

Condensed Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Grant revenue	$ 235	$ 121
Operating expenses:
Operating expenses:	7,332	8,509
Research and development	3,924	3,389
Research and Development Expense, Refund	(1,592)	0
General and administrative	9,664	11,898
Loss from operations	(9,429)	(11,777)
Total operating expenses
Investment Income, Interest	109	12
Net loss
Interest expense	(9,751)	(12,084)
Interest expense	(431)	(319)
Total other income and expense	(322)	(307)
Net loss	(9,751)	(12,084)
Unrealized gain on available-for-sale securities	0	11
Comprehensive loss	$ (9,751)	$ (12,073)
Net loss per share attributable to common stockholders-basic and diluted (in dollars per share)	$ (350)	$ (640)
Weighted-average number of common shares used in net loss per share attributable to common stockholders - basic and diluted	28,152	18,834

Condensed Statements of Compreh

Condensed Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Interest expense	$ (9,751)	$ (12,084)
Other comprehensive income (loss):
Comprehensive loss	$ (9,751)	$ (12,073)

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating activities
Interest expense	$ (9,751)	$ (12,084)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	361	180
Stock-based compensation	1,063	915
Net amortization of premium on investments	0	10
Gain on sale of equipment	115	101
Non-cash interest expense	(1,967)	130
Changes in operating assets and liabilities	(10,179)	(10,748)
Net cash used in operating activities
Investing activities	(577)	(232)
Purchases of property and equipment	33,521	0
Proceeds from maturities of investments	(2,301)	0
Purchases of investments	30,643	(232)
Net cash provided by (used in) investing activities
Proceeds from IPO, net of issuance costs	0	48,367
Repayment of long-term debt	7	26
Payments made under capital lease	7	48,393
Net cash provided by financing activities	20,471	37,413
Net increase in cash and cash equivalents	17,259	20,058
Cash and cash equivalents at beginning of period	37,730	57,471
Cash and cash equivalents at end of period
Supplemental cash flow information	316	218
Cash paid for interest
Accretion of redeemable convertible preferred stock to redemption value	0	(11)
Capital Expenditures Incurred but Not yet Paid	$ 452	$ 0

Organization and operations

Organization and operations	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and operations	Organization and operations The Company Genocea Biosciences, Inc. (the “Company”) is a biopharmaceutical company that was incorporated in Delaware on August 16, 2006 and has a principal place of business in Cambridge, Massachusetts. The Company seeks to discover and develop novel vaccines and immunotherapies to address diseases with significant unmet needs. The Company’s development pipeline consists of candidates discovered using ATLAS TM , a proprietary discovery platform which enables the identification of clinically relevant T cell antigens for novel vaccines and immunotherapies targeting infectious disease and oncology applications. ATLAS is used to rapidly design vaccines and immunotherapies that act, in part, through T cell (or cellular) immune responses, in contrast to approved vaccines and immunotherapies, which are designed to act primarily through B cell (or antibody) immune responses. The Company believes that by harnessing T cells, first-in-class vaccines and immunotherapies can be developed to address diseases where T cells are central to the control of the disease. The Company has one product candidate in active Phase 2 clinical development, GEN-003, an immunotherapy for the treatment of genital herpes. The Company also has, in GEN-004, a Phase 2-ready universal vaccine for the prevention of pneumococcal infections. While internal development of GEN-004 has been suspended, the Company is currently seeking partners to advance GEN-004 into a Phase 1/2 clinical trial targeting toddler and infant populations. The Company also has active research and pre-clinical development programs for diseases including genital herpes, chlamydia, and malaria and is investigating the application of ATLAS to immuno-oncology target discovery. The Company is devoting substantially all of its efforts to product research and development, initial market development, and raising capital. The Company has not generated any product revenue related to its primary business purpose to date and is subject to a number of risks similar to those of other clinical stage companies, including dependence on key individuals, competition from other companies, the need and related uncertainty associated with the development of commercially viable products, and the need to obtain adequate additional financing to fund the development of its product candidates. The Company is also subject to a number of risks similar to other companies in the life sciences industry, including regulatory approval of products, uncertainty of market acceptance of products, competition from substitute products and larger companies, the need to obtain additional financing, compliance with government regulations, protection of proprietary technology, dependence on third parties, product liability, and dependence on key individuals. Liquidity As of March 31, 2016 , the Company had an accumulated deficit of approximately $167.7 million . The Company had cash, cash equivalents and investments of $95.7 million at March 31, 2016 . The Company believes that its existing cash, cash equivalents and investments will be sufficient to fund projected operating expenses and capital expenditure requirements into the second half of 2017. Underwritten public offerings On March 17, 2015, the Company completed an underwritten public offering of its common stock, $0.001 par value per share (“Common Stock”), in which it sold 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, to the public at a price of $8.25 per share. The offering was completed under the shelf registration statement that was filed on Form S-3 and declared effective on March 10, 2015. 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. On August 4 2015, the Company completed an underwritten public offering of its Common Stock in which it sold an aggregate of 3,850,000 shares of Common Stock to the public at a price of $13.00 per share. The offering was completed under the shelf registration statement that was filed on Form S-3 and declared effective May 14, 2015. Net proceeds of the underwritten public offering, after deducting the underwriting discounts and commissions, were $47.0 million , excluding offering expenses of $233 thousand incurred by the Company. At-the-market equity offering program On March 2, 2015, the Company entered into a Sales Agreement with Cowen and Company, LLC (the "Sales Agreement") to establish an at-the-market equity offering program (“ATM”) pursuant to which it was able to offer and sell up to $40 million of its Common Stock at prevailing market prices from time to time. On May 8, 2015, the Sales Agreement was amended to increase the offering amount under the ATM to $50 million of its Common Stock. As of March 31, 2016 , the Company had not commenced sales under this program.

Summary of significant accounti

Summary of significant accounting policies	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies Basis of presentation and use of estimates The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and the instructions of Form 10-Q and Article 10 of Regulation S-X. 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 as of March 31, 2016 and results of operations for the three months ended March 31, 2016 and 2015 . 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, 2015 and the notes thereto which are included in the Company’s Annual Report on Form 10-K, as filed with the SEC on February 17, 2016. 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 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 investments The Company determines the appropriate classification of its investments at the time of purchase. All liquid investments with original maturities of three months or less from the purchase date are considered to be cash equivalents. The Company’s current and non-current investments are comprised of certificates of deposit and government agency securities that are classified as available-for-sale in accordance with ASC 320, Investments—Debt and Equity Securities. The Company classifies investments available to fund current operations as current assets on its balance sheets. Investments are classified as non-current assets on the balance sheets if (i) the Company has the intent and ability to hold the investments for a period of at least one year and (ii) the contractual maturity date of the investments is greater than one year. Available-for-sale investments are recorded at fair value, with unrealized gains or losses included in Accumulated other comprehensive income (loss) on the Company’s balance sheets. Realized gains and losses are determined using the specific identification method and are included as a component of Interest income or Interest expense, respectively. There were no realized gains or losses recognized for the three months ended March 31, 2016 and 2015. The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers its intent to sell, or whether it is more likely than not that the Company will be required to sell the investment before recovery of the investment’s amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, the severity and the duration of the impairment and changes in value subsequent to period end. As of March 31, 2016 , there were no investments with a fair value that was significantly lower than the amortized cost basis or any investments that had been in an unrealized loss position for a significant period. 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. 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 investments (Note 3) and warrants (Note 6). 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 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 debt approximates fair value because the Company’s interest rate yield is near current market rates for comparable debt instruments. The Company’s debt is considered a Level 3 liability within the fair value hierarchy. For the three months ended March 31, 2016 , there were no transfers among Level 1, Level 2, or Level 3 categories. Additionally, there were no changes to the valuation methods utilized by the Company during the three months ended March 31, 2016 . Recently issued accounting standards Standard Description Effect on the financial statements 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. In July 2015, the FASB affirmed its proposal to defer the effective date of the new revenue standard for all entities by one year. As a result, public business entities will be required to apply the new revenue standard to annual reporting periods beginning after December 15, 2017. The standard will become effective for us on January 1, 2018 (the first quarter of our 2018 fiscal year). Early adoption is not permitted under GAAP. 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. The Company is currently evaluating the method of adoption and the impact of this standard on its consolidated financial statements. ASU 2014-15, Presentation of Financial Statements — Going Concern (Subtopic 205-40) In August 2014, the FASB issued ASU 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern. The standard requires an evaluation of whether there are conditions or events, considered in the aggregate, that raise substantial doubt about an 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. ASU 2014-15 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Management has evaluated ASU 2014-15 and believes it could have an impact on the Company’s financial statement disclosures in future reporting periods. Refer to the Liquidity section in Footnote 1 for further details regarding the Company’s liquidity. ASU 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU 2016-02, which replaces the existing lease accounting standards. The new standard requires a dual approach for lessee accounting under which a lessee would account for leases as finance (also referred to as capital) leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use asset and corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the right-of-use asset and for operating leases the lessee would recognize straight-line total lease expense. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. The Company generally does not finance purchases of equipment or other capital, but it does lease office and lab facilities. The Company is evaluating the effect that this ASU will have on its consolidated financial statements and related disclosures. ASU 2016-09, Compensation — Stock Compensation (Topic 718) In March 2016, the FASB issued ASU 2016-09, which provides for improvements to employee share-based payment accounting. The areas for simplification in this update involve several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. The Company is evaluating the impact that this new guidance will have on the consolidated financial statements, but the effect of adoption is not expected to have a material impact to the balance sheet, statement of operations or cash flows.

Cash, cash equivalents and mark

Cash, cash equivalents and marketable securities	3 Months Ended
	Mar. 31, 2016
Cash and Cash Equivalents [Abstract]
Cash, cash equivalents and marketable securities	Cash, cash equivalents and investments As of March 31, 2016 and December 31, 2015 , cash, cash equivalents, and investments comprised funds in depository, money market accounts, and FDIC insured certificates of deposit. At December 31, 2015 , the Company's cash equivalents and investments also included U.S treasury securities. The following table presents the cash equivalents and investments carried at fair value in accordance with the hierarchy defined in Note 2 (in thousands): Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Total (Level 1) (Level 2) (Level 3) March 31, 2016 Money Market funds, included in cash equivalents $ 37,465 $ 37,465 $ — $ — Investments - certificates of deposit 57,926 — 57,926 — Total $ 95,391 $ 37,465 $ 57,926 $ — December 31, 2015 Money Market funds, included in cash equivalents $ 14,207 $ 14,207 $ — $ — U.S treasuries, included in cash equivalents 2,203 2,203 — — Investments - U.S. treasuries 27,924 27,924 — — Investments - certificates of deposit 61,249 — 61,249 — Total $ 105,583 $ 44,334 $ 61,249 $ — Cash equivalents and investments are valued using 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. Investments at March 31, 2016 consist of the following (in thousands): Contracted Amortized Unrealized Unrealized Fair Value Certificates of deposit 91-365 days $ 57,926 $ — $ — $ 57,926 Total $ 57,926 $ — $ — $ 57,926

Long-term debt

Long-term debt	3 Months Ended
	Mar. 31, 2016
Long-term Debt, Unclassified [Abstract]
Long-term debt	4. Long-term debt On November 20, 2014 (the "Closing Date"), 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 (the “2014 Term Loan”). The first tranche of $17.0 million was available through June 30, 2015, of which $12.0 million was drawn down at loan inception and for which approximately $9.8 million of the proceeds were used to repay all outstanding indebtedness under the previously existing $10.0 million loan agreement (the "2013 Term Loan"). The option to draw down the remaining $5.0 million under the first tranche expired unused on June 30, 2015. The second tranche of $5.0 million was subject to certain eligibility requirements which were achieved as of June 30, 2015 and the Company had the option to draw down the second tranche on or prior to December 15, 2015. The second tranche expired unused on December 15, 2015. The Company was not eligible to draw down the third tranche of $5.0 million because the Company did not achieve positive results in its Phase 2a human challenge study of GEN-004. In December 2015, the Company amended the Loan Agreement (the "First Amendment") with Hercules. The First Amendment required the Company to draw an additional $5.0 million and permits the Company to draw two additional $5.0 million tranches. One $5.0 million tranche is immediately available to draw through December 15, 2016 and a second $5.0 million tranche is available to draw through December 15, 2016, subject to the Company demonstrating sufficient evidence of continued clinical progression of its GEN-003 product candidate and making favorable progress in applying its proprietary technology platform toward the development of novel immunotherapies with application in oncology. As of March 31, 2016, the second $5.0 million tranche is not yet available to the Company. At March 31, 2016, $17.0 million was outstanding under the amended 2014 Term Loan. 2014 Term Loan The 2014 Term Loan had an original maturity of July 1, 2018. The eligibility requirements for the second tranche also contained an election for the Company to extend the maturity date to January 1, 2019. During the second quarter of 2015, the Company elected to extend the maturity date of the 2014 Term Loan. The maturity date of January 1, 2019 remained unchanged by the First Amendment. 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 provided for interest-only payments until December 31, 2015, which was extended by the Company for a six -month period as the eligibility requirements for the second tranche were met during the second quarter of 2015. The First Amendment subsequently extended the interest only period through June 30, 2017. Thereafter, beginning July 1, 2017, principal and interest payments will be made monthly for 18 months with a payoff schedule based upon a 30 -month amortization schedule, the original amortization term of the 2014 Term Loan. The remaining unpaid principal is due at January 1, 2019. 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 12 months following the Closing Date, 2.0% , if an advance is prepaid between 12 and 24 months following the Closing Date, and 1.0% thereafter. Amounts outstanding at the time of 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 is also obligated to pay an end of term charge of 4.95% (the "End of Term Charge") 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. Under the provisions of the 2014 Term Loan, the Company has also entered into account control agreements ("ACAs") with Hercules and certain of the Company's financial institutions in which cash, cash equivalents, and investments are held. These ACAs grant Hercules a perfected first priority security interest in the subject accounts. The ACAs do not restrict the Company's ability to utilize cash, cash equivalents, or investments to fund operations and capital expenditures unless there is an Event of Default and Hercules activates its rights under the ACAs. The Loan Agreement contains a material adverse effect provision ("Material Adverse Effect") that requires all material adverse effects 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; or (ii) the ability of the Company to perform the secured obligations in accordance with the terms of the Loan Agreements, or the ability of agent or lender to enforce any of its rights or remedies with respect to the secured obligations; or (iii) the collateral or agent’s liens on the collateral or the priority of such liens. Any event that has or would reasonably be expected to have a Material Adverse Effect is an event of default under the Loan Agreement and repayment of amounts due under the Loan Agreement may be accelerated by Hercules under the same terms as an event of default. Events of default under the Loan Agreement include failure to make any payments of principal or interest as due on any outstanding indebtedness, breach of any covenant, any false or misleading representations or warranties, insolvency or bankruptcy, any attachment or judgment on the Company’s assets of at least $100 thousand, or the occurrence of any material default of the Company involving indebtedness in excess of $100 thousand. If an event of default occurs, repayment of all amounts due under the Loan Agreement may be accelerated by Hercules, including the applicable prepayment charge. In connection with the 2014 Term Loan, 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 2014 Term Loan, 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 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. The Company incurred $280 thousand in debt financing costs related to the First Amendment, which was recorded as a debt discount and will be amortized over the remaining loan term. In connection with the issuance of the 2014 Term Loan, the Company incurred $103 thousand of financing costs and also reimbursed Hercules $210 thousand for debt financing costs, which has been recorded as a debt discount and will be amortized over the remaining loan term. The End of Term Charge is amortized ratably over the term loan period based upon the outstanding debt amount. The increase in the End of Term Charge due to the additional borrowing from the First Amendment is being amortized from the First Amendment date through maturity. 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, 2016, the 2014 Term Loan bears an effective interest rate of 10.2% . As of both March 31, 2016 and December 31, 2015, the Company had outstanding borrowings under the 2014 Term Loan of $17.0 million . Interest expense related to the 2014 Term Loan was $0.4 million and $0.3 million for the three months ended March 31, 2016 and 2015, respectively. Future principal payments, including the End of Term Charge, on the 2014 Term Loan are as follows (in thousands): March 31, 2016 $ — 2017 3,149 2018 6,659 2019 8,034 Total $ 17,842

Commitments and contingencies

Commitments and contingencies	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Lease commitments In February 2014, the Company signed an operating lease for office and laboratory space that commenced in March 2014 and expires in February 2017 (the "2014 Lease"). In June 2015, the Company signed a second operating lease for office space in the same building as the 2014 Lease, which also expires in February 2017 (the "2015 Lease"). The 2015 Lease has one three -year renewal period. The minimum future lease payments under both the 2014 Lease and the 2015 Lease are as follows (in thousands): March 31, 2016 2016 $ 1,039 2017 231 Total $ 1,270 At March 31, 2016 and December 31, 2015 , the Company has an outstanding letter of credit of $316 thousand with a financial institution related to a security deposit for the 2014 Lease, which is secured by cash on deposit and expires on February 28, 2017. An additional unsecured deposit was required for the 2015 Lease. Significant Contracts and Agreements In addition to lease commitments, the Company enters into contractual arrangements that obligate it to make payments to the contractual counterparties upon the occurrence of future events. In the normal course of operations, the Company enters into license and other agreements and intends to continue to seek additional rights related to compounds or technologies in connection with its discovery, manufacturing and development programs. These agreements may require 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) contingent upon the occurrence of future events that cannot be reasonably estimated. In March 2014, the Company announced a joint research collaboration with Dana-Farber Cancer Institute to characterize anti-tumor T cell responses in melanoma patients. This collaboration extends the use of the Company's proprietary ATLAS platform for the rapid discovery of T cell antigens to cancer immunotherapy approaches. Under this agreement, the Company recognized no revenue and $21 thousand for the three months ended March 31, 2016 and 2015, 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 under the agreement of $235 thousand and $100 thousand for the three months ended March 31, 2016 and 2015, respectively. The Company relies on research institutions, contract research organizations, clinical investigators as well as clinical and commercial material manufacturers of our product candidates. Under the terms of these agreements, the Company is obligated to make milestone payments upon the achievement of manufacturing or clinical milestones defined in the contracts. In some cases, monthly service fees for project management services are charged over the duration of the arrangement. In addition, clinical and manufacturing contracts generally require reimbursement to suppliers for certain set-up, production, travel, and other related costs as they are incurred. In some manufacturing contracts, the Company also may be 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. Generally, the Company is liable for actual effort expended by these organizations at any point in time during the contract through the notice period. To the extent amounts paid to a supplier exceed the milestones achieved, the Company records a prepaid asset, and to the extent milestones achieved exceed amounts billed or billable under a contract, an accrual for the estimate of services rendered is recorded. 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 under this agreement of $158 thousand and $2.5 million for the three months ended March 31, 2016 and 2015, respectively. Litigation The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities. Refund of research and development expense In August 2009, the Company entered into an exclusive license and collaboration agreement (the “Novavax Agreement”) with Isconova AB, a Swedish company which subsequently was acquired by Novavax, Inc. ("Novavax"). Pursuant to the agreement, Novavax granted the Company a worldwide, sublicensable, exclusive license to two patent families, to import, make, have made, use, sell, offer for sale and otherwise exploit licensed vaccine products containing an adjuvant which incorporates or is developed from Matrix-A, Matrix-C and/or Matrix-M technology, in the fields of HSV and chlamydia. Matrix-M is the adjuvant used in GEN-003. The Novavax Agreement includes a research funding clause for which the Company made monthly payments to Novavax between August 2009 and March 2012 of approximately $1.6 million . All amounts of research funding provided were to be refunded by Novavax. After December 31, 2015, any amounts remaining due from Novavax, including accrued interest, could be received in cash upon 30 -day written notice provided by the Company. The Company provided this notice in January 2016. The Company provided the research funding solely to benefit the supply plan for the Matrix-M adjuvant to the point that a Phase 1 clinical trial could be initiated. Because of the benefit received from the research funding payments, an assessment of Novavax's financial ability to repay the research funding at the time of the payments, along with the duration of which amounts could be outstanding, the Company concluded the initial research funding should be recorded as research and development expense at the time of payment. In February 2016, upon receipt of the $1.6 million refund including accrued interest, the Company recorded a gain within operating expenses on the Condensed Consolidated Statements of Operations and Comprehensive Loss.

Equity and net loss per share

Equity and net loss per share	3 Months Ended
	Mar. 31, 2016
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Equity and net loss per share	Equity and net loss per share At March 31, 2016 , the Company has authorized 25,000,000 shares of preferred stock at $0.001 par value per share. As of March 31, 2016 and December 31, 2015 , there were no shares of preferred stock issued or outstanding. At March 31, 2016 , the Company has authorized 175,000,000 shares of Common Stock at $0.001 par value per share. As of March 31, 2016 and December 31, 2015 , there were 28,161,010 and 28,161,313 shares of Common Stock issued. As of March 31, 2016 and December 31, 2015 , there were 28,155,302 and 28,151,596 shares of Common Stock outstanding. 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 months ended March 31, 2016 and 2015 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. As of March 31, 2016 and December 31, 2015 , 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 represented warrants to purchase Common Stock issued in periods prior to the Company's initial public offering ("IPO"). 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, 2016 2015 Warrants 78 78 Outstanding options 3,675 2,763 Outstanding ESPP 16 11 Total 3,769 2,852 Restricted stock During 2013, a Company director 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 and unvested shares are subject to repurchase by the Company. 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 both March 31, 2016 and December 31, 2015 , the Company had issued 35,964 shares of restricted Common Stock. The Company had 7,773 and 9,717 shares of nonvested restricted stock that were subject to repurchase by the Company as of March 31, 2016 and December 31, 2015 , respectively.

Stock-based compensation

Stock-based compensation	3 Months Ended
	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
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 the Company's IPO. The 2014 Equity Plan replaced the 2007 Equity Incentive Plan (the “2007 Equity Plan”). The 2014 Equity Plan provides for the grant of incentive stock options, non-qualified stock options, restricted stock and other 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. Pursuant to this provision, on January 1, 2016, the shares available under the 2014 Equity Plan increased by 1,126,064 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 2007 Equity Plan are added to the shares of Common Stock available for issuance under the 2014 Equity Plan. As of March 31, 2016, the number of options available for grant is 694,119 shares and the total number of Common Stock shares that may be issued is 4,369,469 . 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, 2016 2015 Research and development $ 463 $ 415 General and administrative 600 500 Total $ 1,063 $ 915 Stock options The following table summarizes stock option activity for employees and nonemployees (shares in thousands): Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2015 2,723 $ 7.60 7.61 $ 2,840 Granted 1,042 $ 3.12 Exercised (3 ) $ 2.83 Canceled (87 ) $ 8.68 Outstanding at March 31, 2016 3,675 $ 6.31 7.94 $ 10,383 Exercisable at March 31, 2016 1,557 $ 5.97 6.47 $ 5,046 Vested or expected to vest at March 31, 2016 3,675 $ 6.31 7.94 $ 10,383 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. The Company determined that none of the performance-based milestones were probable of achievement during the three months ended March 31, 2016 , and accordingly did not recognize stock-based compensation expense for these periods. As of March 31, 2016 , 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 the Company's 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. As of March 31, 2016, 144,242 shares remain for future issuance under the plan. The Company incurred stock-based compensation expense related to the 2014 ESPP of $33 thousand for the three months ended March 31, 2016 and $26 thousand for the three months ended March 31, 2015

Income taxes

Income taxes	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income taxes	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, 2016 and 2015. 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.

Summary of significant accoun14

Summary of significant accounting policies (Policies)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Internal Use Software, Policy [Policy Text Block]
Basis of presentation	The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and the instructions of Form 10-Q and Article 10 of Regulation S-X. 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 as of March 31, 2016 and results of operations for the three months ended March 31, 2016 and 2015 . 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, 2015 and the notes thereto which are included in the Company’s Annual Report on Form 10-K, as filed with the SEC on February 17, 2016.
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 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.
Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block]	The Company determines the appropriate classification of its investments at the time of purchase. All liquid investments with original maturities of three months or less from the purchase date are considered to be cash equivalents. The Company’s current and non-current investments are comprised of certificates of deposit and government agency securities that are classified as available-for-sale in accordance with ASC 320, Investments—Debt and Equity Securities. The Company classifies investments available to fund current operations as current assets on its balance sheets. Investments are classified as non-current assets on the balance sheets if (i) the Company has the intent and ability to hold the investments for a period of at least one year and (ii) the contractual maturity date of the investments is greater than one year. Available-for-sale investments are recorded at fair value, with unrealized gains or losses included in Accumulated other comprehensive income (loss) on the Company’s balance sheets. Realized gains and losses are determined using the specific identification method and are included as a component of Interest income or Interest expense, respectively. There were no realized gains or losses recognized for the three months ended March 31, 2016 and 2015. The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers its intent to sell, or whether it is more likely than not that the Company will be required to sell the investment before recovery of the investment’s amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, the severity and the duration of the impairment and changes in value subsequent to period end. As of March 31, 2016 , there were no investments with a fair value that was significantly lower than the amortized cost basis or any investments that had been in an unrealized loss position for a significant period.
Deferred financing costs
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. 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 investments (Note 3) and warrants (Note 6). 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 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 debt approximates fair value because the Company’s interest rate yield is near current market rates for comparable debt instruments. The Company’s debt is considered a Level 3 liability within the fair value hierarchy.
Recently issued accounting standards	Recently issued accounting standards Standard Description Effect on the financial statements 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. In July 2015, the FASB affirmed its proposal to defer the effective date of the new revenue standard for all entities by one year. As a result, public business entities will be required to apply the new revenue standard to annual reporting periods beginning after December 15, 2017. The standard will become effective for us on January 1, 2018 (the first quarter of our 2018 fiscal year). Early adoption is not permitted under GAAP. 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. The Company is currently evaluating the method of adoption and the impact of this standard on its consolidated financial statements. ASU 2014-15, Presentation of Financial Statements — Going Concern (Subtopic 205-40) In August 2014, the FASB issued ASU 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern. The standard requires an evaluation of whether there are conditions or events, considered in the aggregate, that raise substantial doubt about an 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. ASU 2014-15 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Management has evaluated ASU 2014-15 and believes it could have an impact on the Company’s financial statement disclosures in future reporting periods. Refer to the Liquidity section in Footnote 1 for further details regarding the Company’s liquidity. ASU 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU 2016-02, which replaces the existing lease accounting standards. The new standard requires a dual approach for lessee accounting under which a lessee would account for leases as finance (also referred to as capital) leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use asset and corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the right-of-use asset and for operating leases the lessee would recognize straight-line total lease expense. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. The Company generally does not finance purchases of equipment or other capital, but it does lease office and lab facilities. The Company is evaluating the effect that this ASU will have on its consolidated financial statements and related disclosures. ASU 2016-09, Compensation — Stock Compensation (Topic 718) In March 2016, the FASB issued ASU 2016-09, which provides for improvements to employee share-based payment accounting. The areas for simplification in this update involve several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. The Company is evaluating the impact that this new guidance will have on the consolidated financial statements, but the effect of adoption is not expected to have a material impact to the balance sheet, statement of operations or cash flows.

Summary of significant accoun15

Summary of significant accounting policies (Tables)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Schedule of recent accounting pronouncements	Standard Description Effect on the financial statements 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. In July 2015, the FASB affirmed its proposal to defer the effective date of the new revenue standard for all entities by one year. As a result, public business entities will be required to apply the new revenue standard to annual reporting periods beginning after December 15, 2017. The standard will become effective for us on January 1, 2018 (the first quarter of our 2018 fiscal year). Early adoption is not permitted under GAAP. 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. The Company is currently evaluating the method of adoption and the impact of this standard on its consolidated financial statements. ASU 2014-15, Presentation of Financial Statements — Going Concern (Subtopic 205-40) In August 2014, the FASB issued ASU 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern. The standard requires an evaluation of whether there are conditions or events, considered in the aggregate, that raise substantial doubt about an 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. ASU 2014-15 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Management has evaluated ASU 2014-15 and believes it could have an impact on the Company’s financial statement disclosures in future reporting periods. Refer to the Liquidity section in Footnote 1 for further details regarding the Company’s liquidity. ASU 2016-02, Leases (Topic 842) In February 2016, the FASB issued ASU 2016-02, which replaces the existing lease accounting standards. The new standard requires a dual approach for lessee accounting under which a lessee would account for leases as finance (also referred to as capital) leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use asset and corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the right-of-use asset and for operating leases the lessee would recognize straight-line total lease expense. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. The Company generally does not finance purchases of equipment or other capital, but it does lease office and lab facilities. The Company is evaluating the effect that this ASU will have on its consolidated financial statements and related disclosures. ASU 2016-09, Compensation — Stock Compensation (Topic 718) In March 2016, the FASB issued ASU 2016-09, which provides for improvements to employee share-based payment accounting. The areas for simplification in this update involve several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. The Company is evaluating the impact that this new guidance will have on the consolidated financial statements, but the effect of adoption is not expected to have a material impact to the balance sheet, statement of operations or cash flows.

Cash, cash equivalents and ma16

Cash, cash equivalents and marketable securities (Tables)	3 Months Ended
	Mar. 31, 2016
Cash and Cash Equivalents [Abstract]
Schedule of cash, cash equivalents and marketable securities carried at fair value	The following table presents the cash equivalents and investments carried at fair value in accordance with the hierarchy defined in Note 2 (in thousands): Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Total (Level 1) (Level 2) (Level 3) March 31, 2016 Money Market funds, included in cash equivalents $ 37,465 $ 37,465 $ — $ — Investments - certificates of deposit 57,926 — 57,926 — Total $ 95,391 $ 37,465 $ 57,926 $ — December 31, 2015 Money Market funds, included in cash equivalents $ 14,207 $ 14,207 $ — $ — U.S treasuries, included in cash equivalents 2,203 2,203 — — Investments - U.S. treasuries 27,924 27,924 — — Investments - certificates of deposit 61,249 — 61,249 — Total $ 105,583 $ 44,334 $ 61,249 $ —
Schedule of marketable securities	at March 31, 2016 consist of the following (in thousands): Contracted Amortized Unrealized Unrealized Fair Value Certificates of deposit 91-365 days $ 57,926 $ — $ — $ 57,926 Total $ 57,926 $ — $ — $ 57,926

Long-term debt (Tables)

Long-term debt (Tables)	3 Months Ended
	Mar. 31, 2016
Long-term Debt, Unclassified [Abstract]
Schedule of future principal payments on the new term loan	Future principal payments, including the End of Term Charge, on the 2014 Term Loan are as follows (in thousands): March 31, 2016 $ — 2017 3,149 2018 6,659 2019 8,034 Total $ 17,842

Commitments and contingencies (

Commitments and contingencies (Tables)	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments for operating leases	The minimum future lease payments under both the 2014 Lease and the 2015 Lease are as follows (in thousands): March 31, 2016 2016 $ 1,039 2017 231 Total $ 1,270

Common stock (Tables)

Common stock (Tables)	3 Months Ended
	Mar. 31, 2016
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
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, 2016 2015 Warrants 78 78 Outstanding options 3,675 2,763 Outstanding ESPP 16 11 Total 3,769 2,852

Stock-based compensation (Table

Stock-based compensation (Tables)	3 Months Ended
	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
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, 2016 2015 Research and development $ 463 $ 415 General and administrative 600 500 Total $ 1,063 $ 915
Schedule of stock option activity for employees and nonemployees	The following table summarizes stock option activity for employees and nonemployees (shares in thousands): Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2015 2,723 $ 7.60 7.61 $ 2,840 Granted 1,042 $ 3.12 Exercised (3 ) $ 2.83 Canceled (87 ) $ 8.68 Outstanding at March 31, 2016 3,675 $ 6.31 7.94 $ 10,383 Exercisable at March 31, 2016 1,557 $ 5.97 6.47 $ 5,046 Vested or expected to vest at March 31, 2016 3,675 $ 6.31 7.94 $ 10,383

Organization and operations (De

Organization and operations (Details)	3 Months Ended
	Mar. 31, 2016product
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of products in clinical development	1

Organization and operations (22

Organization and operations (Details 2) - USD ($) $ / shares in Units, $ in Thousands	Aug. 04, 2015	Mar. 17, 2015	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	May. 08, 2015	Mar. 02, 2015
Underwritten public offering
Cash equivalents and investments			$ 95,700
Common stock			$ (167,661)		$ (157,910)
Common stock, par value (in dollars per share)			$ 0.001		$ 0.001
Proceeds from sale of common stock, net of issuance costs			$ 0	$ 48,367
At-the-market equity offering program, maximum value of common stock to offer and sale						$ 50,000	$ 40,000
Underwritten public offering
Underwritten public offering
Common stock, par value (in dollars per share)		$ 0.001
Issuance of common stock (in shares)	3,850,000	6,272,726
Share price	$ 13	$ 8.25
Proceeds from sale of common stock, net of issuance costs	$ 47,000	$ 48,600
Offering expenses	$ 233	$ 276
Over-allotment option
Underwritten public offering
Issuance of common stock (in shares)		818,181

Cash, cash equivalents and ma23

Cash, cash equivalents and marketable securities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Cash, cash equivalents and marketable securities
Cash and cash equivalents	$ 37,730	$ 17,259	$ 57,471	$ 20,058
Recurring | Quoted prices in active markets (Level 1)
Cash, cash equivalents and marketable securities
March 31, 2016	37,465	14,207
Certificates of Deposit, at Carrying Value	0	0
Total	37,465	44,334
Recurring | Fair Value, Inputs, Level 2 [Member]
Cash, cash equivalents and marketable securities
March 31, 2016	0
Certificates of Deposit, at Carrying Value	57,926	61,249
Total	57,926	61,249
Recurring | U.S. Treasuries | Quoted prices in active markets (Level 1)
Cash, cash equivalents and marketable securities
Certificates of deposit, included in cash equivalents		27,924
Total		2,203
Recurring | Total
Cash, cash equivalents and marketable securities
March 31, 2016	37,465	14,207
Certificates of Deposit, at Carrying Value	57,926	61,249
Total	$ 95,391	105,583
Recurring | Total | U.S. Treasuries
Cash, cash equivalents and marketable securities
Certificates of deposit, included in cash equivalents		27,924
Total		$ 2,203

Cash, cash equivalents and ma24

Cash, cash equivalents and marketable securities (Details 2) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Marketable securities
Fair Value, Total	$ 57,926	$ 77,069
U.S. Treasuries
Marketable securities
Amortized Cost, Total	57,926
Unrealized Gains, Total	0
Fair Value, Total	57,926
Certificates of Deposit [Member]
Marketable securities
Time Deposit Maturities, Next Rolling Twelve Months	$ 57,926

Long-term debt (Details)

Long-term debt (Details)	Aug. 04, 2015USD ($)shares	Mar. 17, 2015USD ($)shares	Nov. 20, 2014USD ($)tranche$ / sharesshares	Mar. 31, 2016USD ($)shares	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)tranche
Common stock
Long-Term Debt
Exercisable amount (in shares) | shares				77,603
Line of Credit | 2013 Term Loan
Long-Term Debt
Debt financing			$ 10,000,000
Repay indebtedness			9,800,000
Line of Credit | 2014 Term Loan
Long-Term Debt
Debt financing			$ 27,000,000
Tranches, number | tranche			3
Interest rate (as a percent)			7.25%
Number of monthly payments of principal and accrued interest			30 months
Prepayment, written notice period			7 months
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
Financing costs				$ 280,000
Debt discount			$ 210,000
Debt Instrument, Interest Rate, Effective Percentage				10.20%
Outstanding borrowings				$ 17,000,000		$ 17,000,000
Interest Expense, Debt				400,000	$ 300,000
Debt Instrument, Extension, Term			6 months
Debt Instrument Periodic Payment Term			18 months
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
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	17,000,000
Expired borrowing capacity				$ 5,000,000
Line of Credit | Term Loan 2014, First Amendment
Long-Term Debt
Debt financing						$ 5,000,000
Tranches, number | tranche						2
Line of Credit | Term Loan 2014, First Amendment, Tranche 1
Long-Term Debt
Debt financing						$ 5,000,000
Line of Credit | Term Loan 2014, First Amendment, Tranche 2
Long-Term Debt
Debt financing						$ 5,000,000
Hercules Technology Growth Capital, Inc. | Common stock
Long-Term Debt
Exercisable amount (in shares) | shares			73,725	73,725
Warrant, exercisable, value			$ 607,500
Exercise price of warrant (in dollars per share) | $ / shares			$ 8.24
Private Placement | Hercules Technology Growth Capital, Inc.
Long-Term Debt
Issuance of common stock (in shares) | shares			223,463
Issuance of common stock			$ 2,000,000
Financing costs allocated to additional paid-in capital			$ 36,000
Underwritten public offering
Long-Term Debt
Issuance of common stock (in shares) | shares	3,850,000	6,272,726
Financing costs allocated to additional paid-in capital	$ 233,000	$ 276,000

Long-term debt (Details 2)

Long-term debt (Details 2) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Future principal payments
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	$ 0
2014 Term Loan | Line of Credit
Future principal payments
2,016	3,149,000
2,017	6,659,000
2,018	8,034,000
2,019	17,842,000
Total	$ 17,000,000	$ 17,000,000

Warrants (Details)

Warrants (Details) - shares	Mar. 31, 2016	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
Hercules Technology Growth Capital, Inc. | Common stock
Warrants
Warrants (in shares)	73,725	73,725

Commitments and contingencies28

Commitments and contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)Renewal	Mar. 31, 2016USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016		$ 1,039
2,017		231
Total		1,270
June 2015 Operating Lease Due February 2017
Restricted cash related to facilities leases
Number of Renewal Terms | Renewal	1
Lessee Leasing Arrangements, Operating Leases, Renewal Term	3 years
2012 Master Facilities Lease
Restricted cash related to facilities leases
Restricted cash	$ 316	$ 316

Commitments and contingencies29

Commitments and contingencies (Details 2) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Sep. 30, 2014	Mar. 31, 2016	Mar. 31, 2015
Commitments and contingencies
Grant revenue		$ 235	$ 121
Bill and Melinda Gates Foundation
Commitments and contingencies
Grant revenue		235	100
Grant received	$ 1,200
Joint research collaboration agreement | Dana-Farber Cancer Institute and Harvard Medical School
Commitments and contingencies
Grant revenue		$ 0	$ 21

Commitments and contingencies30

Commitments and contingencies (Details 3) $ in Thousands	3 Months Ended		32 Months Ended
	Mar. 31, 2016USD ($)product	Mar. 31, 2015USD ($)	Mar. 31, 2012USD ($)
Commitments and contingencies
Amount expensed related to supply agreements	$ 7,332	$ 8,509
Number Of Patent Families | product	2
Refund Notice Period	30 days
Novavax
Commitments and contingencies
Research and Development Arrangement, Agreement with Third Party, Third Party Funding to Offset Costs Incurred			$ 1,600
Supply agreement | Fujifilm
Commitments and contingencies
Amount expensed related to supply agreements	$ 158	$ 2,500

Common stock (Details)

Common stock (Details)	Jan. 20, 2014	Mar. 31, 2016$ / sharesshares	Mar. 31, 2015shares	Dec. 31, 2015$ / sharesshares	Dec. 31, 2013shares	Nov. 20, 2014shares
Common stock
Preferred stock, shares authorized		25,000,000		25,000,000
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.001		$ 0.001
Preferred stock, shares issued		0		0
Preferred stock, shares outstanding		0		0
Common stock, shares authorized		175,000,000		175,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.001		$ 0.001
Common stock, shares issued		28,161,010		28,161,313
Common stock, shares outstanding		28,155,302		28,151,596
Reverse stock split	0.0840
Earnings Per Share, Diluted [Abstract]
Common stock equivalents (in shares)		3,769,000	2,852,000
Outstanding options
Common stock
Options exercised (in shares)		3,000
Restricted common stock
Common stock
Vesting period		4 years
Number of shares issued		35,964		35,964
Number of shares subject to repurchase by entity		7,773		9,717
Director | Outstanding options
Common stock
Options exercised (in shares)					31,092
Employee Stock Purchase Plan
Earnings Per Share, Diluted [Abstract]
Common stock equivalents (in shares)		16,000	11,000
Warrants
Earnings Per Share, Diluted [Abstract]
Common stock equivalents (in shares)		78,000	78,000
Outstanding options
Earnings Per Share, Diluted [Abstract]
Common stock equivalents (in shares)		3,675,000	2,763,000
Common stock
Earnings Per Share, Diluted [Abstract]
Exercisable amount (in shares)		77,603
Warrants to purchase redeemable convertible preferred stock automatically converted to warrants to purchase common stock
Earnings Per Share, Diluted [Abstract]
Exercisable amount (in shares)		3,878
Hercules Technology Growth Capital, Inc. | Common stock
Earnings Per Share, Diluted [Abstract]
Exercisable amount (in shares)		73,725				73,725

Stock-based compensation (Detai

Stock-based compensation (Details) - shares	Jan. 01, 2015	Mar. 31, 2016	Dec. 31, 2015
2014 Equity Plan
Stock-based compensation
Number of shares authorized		903,494
Increase in shares	1,126,064
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		4,369,469	694,119

Stock-based compensation (Det33

Stock-based compensation (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stock Based Compensation Expense
Stock-based compensation expense	$ 1,063	$ 915
Research and development
Stock Based Compensation Expense
Stock-based compensation expense	463	415
General and administrative
Stock Based Compensation Expense
Stock-based compensation expense	$ 600	$ 500

Stock-based compensation (Det34

Stock-based compensation (Details 3) - Outstanding options - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Shares
Outstanding at the beginning of the period (in shares)	2,723
Granted (in shares)	1,042
Exercised (in shares)	(3)
Canceled (in shares)	(87)
Outstanding at the end of the period (in shares)	3,675	2,723
Exercisable at the end of the period (in shares)	1,557
Vested or expected to vest at the end of the period (in shares)	3,675
Weighted - Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 7.60
Granted (in dollars per share)	3.12
Exercised (in dollars per share)	2.83
Canceled (in dollars per share)	8.68
Outstanding at the end of the period (in dollars per share)	6.31	$ 7.60
Exercisable at the end of the period (in dollars per share)	5.97
Vested or expected to vest at the end of the period (in dollars per share)	$ 6.31
Weighted- Average Remaining Contractual Term
Outstanding at the beginning/end of the period	7 years 11 months 9 days	7 years 7 months 10 days
Exercisable at the end of the period	6 years 5 months 19 days
Vested or expected to vest at the end of the period	7 years 11 months 9 days
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars)	$ 10,383	$ 2,840
Exercisable at the end of the period (in dollars)	5,046
Vested or expected to vest at the end of the period (in dollars)	$ 10,383

Stock-based compensation (Det35

Stock-based compensation (Details 4) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Additional disclosures
Stock-based compensation expense	$ 1,063,000	$ 915,000
Performance-based stock options
Additional disclosures
Stock-based compensation expense	$ 0
Options outstanding (in shares)	56,336
Employee stock purchase plan | 2014 ESPP
Additional disclosures
Stock-based compensation expense	$ 33,000	$ 26,000
Number of shares of common stock authorized under the plan	200,776
Option period	6 months
Shares remaining for future issuance (in shares)	144,242