Genocea Biosciences (GNCAQ) 10-Q 6 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Aug. 04, 2015
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	Jun. 30, 2015
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		28,060,240
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 49,580	$ 20,058
Marketable securities	25,015	27,021
Prepaid expenses and other current assets	770	934
Total current assets	75,365	48,013
Property and equipment, net	2,557	1,956
Restricted cash	316	316
Other non-current assets	478	47
Total assets	78,716	50,332
Current liabilities:
Accounts payable	1,411	2,692
Accrued expenses and other current liabilities	4,160	2,486
Deferred revenue	670	555
Other current liabilities	125	107
Total current liabilities	6,366	5,840
Non-current liabilities:
Long-term debt	11,564	11,389
Deferred revenue, net of current portion	0	350
Other non-current liabilities	124	246
Total liabilities	$ 18,054	$ 17,825
Commitments and contingencies (Note 6)
Stockholders’ equity:
Preferred stock	$ 0	$ 0
Common stock	24	18
Additional paid-in-capital	198,456	147,923
Accumulated other comprehensive income (loss)	7	(7)
Accumulated deficit	(137,825)	(115,427)
Total stockholders’ equity	60,662	32,507
Total liabilities and stockholders’ equity	$ 78,716	$ 50,332

Condensed Statements of Operati

Condensed Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Grant revenue	$ 115	$ 0	$ 236	$ 0
Operating expenses:
Research and development	6,969	4,551	15,478	8,958
General and administrative	3,172	2,358	6,561	4,324
Total operating expenses	10,141	6,909	22,039	13,282
Loss from operations	(10,026)	(6,909)	(21,803)	(13,282)
Other expense:
Change in fair value of warrants	0	0	0	(725)
Interest expense, net	(288)	(237)	(595)	(468)
Other expense	(288)	(237)	(595)	(1,193)
Net loss	(10,314)	(7,146)	(22,398)	(14,475)
Reconciliation of net loss to net loss applicable to common stockholders
Net loss	(10,314)	(7,146)	(22,398)	(14,475)
Accretion of redeemable convertible preferred stock to redemption value	0	0	0	(180)
Net loss attributable to common stockholders	$ (10,314)	$ (7,146)	$ (22,398)	$ (14,655)
Net loss per share attributable to common stockholders-basic and diluted (in dollars per share)	$ (0.43)	$ (0.41)	$ (1.04)	$ (1.08)
Weighted-average number of common shares used in net loss per share attributable to common stockholders - basic and diluted	24,154	17,346	21,510	13,623

Condensed Statements of Compreh

Condensed Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (10,314)	$ (7,146)	$ (22,398)	$ (14,475)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	3	(1)	14	(1)
Comprehensive loss	$ (10,311)	$ (7,147)	$ (22,384)	$ (14,476)

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities
Net loss	$ (22,398)	$ (14,475)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	391	160
Stock-based compensation	1,946	1,549
Net amortization of premium on investments	20	4
Change in fair value of warrants liability	0	725
Non-cash interest expense	175	40
Changes in operating assets and liabilities	(206)	(970)
Net cash used in operating activities	(20,072)	(12,967)
Investing activities
Purchases of property and equipment	(993)	(202)
Proceeds from maturities of marketable securities	2,000	0
Purchase of marketable securities	0	(27,053)
Net cash provided by (used in) investing activities	1,007	(27,255)
Financing activities
Proceeds from IPO, net of issuance costs	0	59,974
Proceeds from underwritten public offering, net of issuance costs	48,369	0
Proceeds from exercise of stock options	101	135
Proceeds from the exercise of warrants	0	33
Proceeds from the issuance of common stock under ESPP	119	0
Payments made under capital lease	(2)	0
Net cash provided by financing activities	48,587	60,142
Net increase in cash and cash equivalents	29,522	19,920
Cash and cash equivalents at beginning of period	20,058	12,208
Cash and cash equivalents at end of period	49,580	32,128
Supplemental cash flow information
Cash paid for interest	438	378
Supplemental disclosure of non-cash investing and financing activities
Conversion of preferred stock to common stock upon closing of IPO	0	81,774
Reclassification of prepaid IPO closing costs from non-current assets to additional paid-in capital	0	998
Reclassification of warrants to additional paid-in capital	0	1,381
Accretion of redeemable convertible preferred stock to redemption value	0	180
Vesting of restricted stock	$ 5	$ 5

Organization and operations

Organization and operations	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and operations	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, currently in Phase 2 clinical development. The Company reported positive top-line data from an ongoing Phase 2 dose optimization trial from the immediate post dosing 28-day observation period in May 2015. The Company identified an improved dose of 60μg per protein/75μg of adjuvant, which demonstrated a highly statistically significant reduction (p<0.0001) from baseline in the viral shedding rate (55%) and genital lesion rate (60%). Data from the six-month and 12-month observation periods in this trial is expected in the fourth quarter of 2015 and the first quarter of 2016, respectively. • 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 proof-of-efficacy data in the fourth quarter of 2015. The Company also has other product candidates that are currently in preclinical development and ongoing discovery research activities in infectious disease and immuno-oncology applications. 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 T cell-directed vaccines and immunotherapies in the areas of infectious disease, immuno-oncology and autoimmune disorders. 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 underwriters have a 30-day option, from the commencement date of July 30, 2015, to purchase an additional 577,500 shares of Common Stock. The offering was completed under the shelf registration statement that was filed on Form S-3 and declared effective May 14, 2015 (the “Registration Statement”). Net proceeds of the underwritten public offering, after deducting the underwriting discounts and commissions, were $47.0 million , excluding estimated offering expenses of $146 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 June 30, 2015 , the Company had not commenced sales under this program.

Summary of significant accounti

Summary of significant accounting policies	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies Basis of presentation and use of estimates The accompanying unaudited condensed 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 June 30, 2015 and results of operations for the three and six months ended June 30, 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. Deferred financing costs Offering costs related to debt and equity financing primarily consist of direct and incremental external expenses. In April 2015, the FASB issued ASU No. 2015-03 Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”). ASU 2015-03 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 also requires adoption 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 and early adoption is permitted. As of June 30, 2015 , the Company early adopted the provisions of ASU 2015-03. Approximately $85 thousand , as of June 30, 2015 , and $99 thousand , as of December 31, 2014 , of unamortized capitalized debt issuance costs previously included in both other current and other non-current assets was reclassified to a direct deduction of the carrying value of the debt liability. The adoption of this standard did not have material impact on the Company’s financial conditions, results of operations, or cash flows. The amortization of deferred debt financing costs follows the effective interest rate method and was not impacted by the issuance or adoption of ASU 2015-03. Offering costs related to the Registration Statement and the initiation of the ATM are recorded as an asset and are reclassified to equity on a pro-rata basis based upon the successful selling of common shares compared to the available limits in either equity program. The costs are reviewed for impairment and will be recorded to expense if and when the Company determines that future equity offerings are not probable of occurring or the Registration Statement and ATM are no longer available. At June 30, 2015 , the Company had $293 thousand of deferred offering costs recorded as a non-current asset. 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). 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 for comparable debt instruments. The Company’s long-term debt is considered a Level 3 liability within the fair value hierarchy. For the six months ended June 30, 2015 , 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 six months ended June 30, 2015 . 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 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. 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.

Cash, cash equivalents and mark

Cash, cash equivalents and marketable securities	6 Months Ended
	Jun. 30, 2015
Cash and Cash Equivalents [Abstract]
Cash, cash equivalents and marketable securities	Cash, cash equivalents and marketable securities As of June 30, 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): Total Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) June 30, 2015 Money Market funds, included in cash equivalents $ 49,009 $ 49,009 — — Marketable securities - U.S. treasuries 25,015 25,015 — — Total $ 74,024 $ 74,024 $ — $ — December 31, 2014 Money Market funds, included in cash equivalents $ 18,992 $ 18,992 — — Marketable securities - U.S. treasuries 27,021 27,021 — — Total $ 46,013 $ 46,013 $ — $ — Cash equivalents and marketable securities 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. Marketable securities at June 30, 2015 consist of the following (in thousands): Contracted Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value Current U.S. Treasuries 15-184 days $ 25,008 $ 7 $ — $ 25,015 Total $ 25,008 $ 7 $ — $ 25,015

Long-term debt

Long-term debt	6 Months Ended
	Jun. 30, 2015
Long-term Debt, Unclassified [Abstract]
Long-term debt	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 was available through June 30, 2015 , of which $12.0 million was drawn down at loan inception. 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. The Company has the option to draw down the second tranche on or prior to December 15, 2015. The Company would be eligible to draw down the third tranche of $5.0 million provided that favorable data from the ongoing Phase 2a human challenge study for GEN-004 is achieved prior to December 15, 2015. The Company has not achieved the requirements to draw down the third tranche as of June 30, 2015 . 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. The Company elected to extend the maturity date on the 2014 Term Loan as of June 30, 2015 . 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 for a six-month period at the Company’s sole election as the eligibility requirements for the second tranche were met as of June 30, 2015. Thereafter, beginning July 1, 2016, 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 as an off-set to the outstanding principal balance. 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. Future principal payments due on the 2014 Term Loan are as follows (in thousands): June 30, 2015 $ — 2016 2,223 2017 4,700 2018 5,058 2019 19 Total $ 12,000

Warrants

Warrants	6 Months Ended
	Jun. 30, 2015
Warrants and Rights Note Disclosure [Abstract]
Warrants	Warrants As of June 30, 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, 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. 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 June 30, 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 June 30, 2015 and December 31, 2014 , 3,878 of these common stock warrants remained outstanding.

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies 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 minimum future lease payments under both the 2014 Lease and the 2015 Lease are as follows (in thousands): June 30, 2015 2015 $ 675 2016 1,379 2017 231 Total $ 2,285 At June 30, 2015 and December 31, 2014 , 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. 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 entered into license and other agreements and intend to continue to seek additional rights relating to compounds or technologies in connection with our 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 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 under the agreement of $9 thousand and $30 thousand for the three and six months ended June 30, 2015 , respectively, and none for the three and six months ended June 30, 2014 . 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 $115 thousand and $236 thousand for the three and six months ended June 30, 2015 . 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 fee 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 $1.1 million and $3.6 million for the three and six months ended June 30, 2015 , respectively and $412 thousand and $437 thousand for the three and six months ended June 30, 2014 , respectively. Litigation The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities.

Equity and net loss per share

Equity and net loss per share	6 Months Ended
	Jun. 30, 2015
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Equity and net loss per share	Equity and net loss per share At June 30, 2015 , the Company has authorized 25,000,000 shares of preferred stock at $0.001 par value per share. As of June 30, 2015 and December 31, 2014 , there were no shares of preferred stock issued or outstanding. At June 30, 2015 , the Company has authorized 175,000,000 shares of common stock at $0.001 par value per share. As of June 30, 2015 and December 31, 2014 , there were 24,204,463 and 17,869,235 shares of common stock issued. As of June 30, 2015 and December 31, 2014 , there were 24,191,511 and 17,852,389 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 and six months ended June 30, 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): Six Months Ended June 30, 2015 2014 Warrants 78 4 Outstanding options 2,760 2,234 Total 2,838 2,238 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. 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 December 31, 2014 and June 30, 2015 , the Company had issued 35,964 shares of restricted Common Stock. The Company had 16,840 and 12,952 shares of nonvested restricted stock that were subject to repurchase by the Company as of December 31, 2014 and June 30, 2015 , respectively.

Stock-based compensation

Stock-based compensation	6 Months Ended
	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation	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 provides 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. Pursuant to this provision, on January 1, 2015, the shares available under the 2014 Equity Plan increased by 714,769 shares of Common Stock. The 2014 Equity Plan also allows for shares of Common Stock underlying awards that are cancelled, forfeited, repurchased, expire or are otherwise terminated to be added to the shares of Common Stock available for issuance under the 2014 Equity Plan. Outstanding option awards granted under the 2007 Equity Plan, at the time of the adoption of the 2014 Equity Plan, remain outstanding and effective. As of June 30, 2015 , 284,913 shares remain available for future grants under the 2014 Equity Plan. Including options outstanding as of June 30, 2015 , under both the 2007 Equity Plan and the 2014 Equity Plan and including shares still available for future awards under the 2014 Equity Plan, 3,044,717 of common shares may be issued under option award plans. 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 June 30, Six Months Ended June 30, 2015 2014 2015 2014 Research and development $ 450 $ 371 $ 865 $ 848 General and administrative 581 297 1,081 701 Total $ 1,031 $ 668 $ 1,946 $ 1,549 Stock Options The following table summarizes stock option activity for employees and nonemployees (shares in thousands): Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at December 31, 2014 2,290 $ 7.26 8.08 $ 5,332 Granted 588 $ 9.31 Exercised (42 ) $ 2.38 Canceled (76 ) $ 15.61 Outstanding at June 30, 2015 2,760 $ 7.55 7.88 $ 18,061 Exercisable at June 30, 2015 1,248 $ 4.87 6.52 $ 11,372 Vested or expected to vest at June 30, 2015 2,611 $ 7.45 7.83 $ 17,345 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 and six months ended June 30, 2015 , and accordingly did not recognize stock-based compensation expense for these periods. No stock-based compensation was recorded for the three months ended June 30, 2014 and $435 thousand was recorded for the six months ended June 30, 2014 . The stock-based compensation recorded for the six months ended June 30, 2014 was due to the achievement of milestones and subsequent vesting of 96,988 performance-based options in first quarter of 2014. As of June 30, 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 period under the 2014 ESPP began on July 1, 2014. During the six months ended June 30, 2015 , 15,622 shares were issued under the 2014 ESPP, with 165,085 shares remaining for future issuance under the plan as of June 30, 2015 . The Company incurred stock-based compensation expense related to the 2014 ESPP of $26 thousand and $53 thousand for the three and six months ended June 30, 2015 , respectively, and none for the three and six months ended June 30, 2014 .

Income taxes

Income taxes	6 Months Ended
	Jun. 30, 2015
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 and six months ended June 30, 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.

Summary of significant accoun15

Summary of significant accounting policies (Policies)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Basis of presentation	The accompanying unaudited condensed 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 June 30, 2015 and results of operations for the three and six months ended June 30, 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.
Deferred financing costs	Deferred financing costs Offering costs related to debt and equity financing primarily consist of direct and incremental external expenses. In April 2015, the FASB issued ASU No. 2015-03 Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”). ASU 2015-03 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 also requires adoption 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 and early adoption is permitted. As of June 30, 2015 , the Company early adopted the provisions of ASU 2015-03. Approximately $85 thousand , as of June 30, 2015 , and $99 thousand , as of December 31, 2014 , of unamortized capitalized debt issuance costs previously included in both other current and other non-current assets was reclassified to a direct deduction of the carrying value of the debt liability. The adoption of this standard did not have material impact on the Company’s financial conditions, results of operations, or cash flows. The amortization of deferred debt financing costs follows the effective interest rate method and was not impacted by the issuance or adoption of ASU 2015-03. Offering costs related to the Registration Statement and the initiation of the ATM are recorded as an asset and are reclassified to equity on a pro-rata basis based upon the successful selling of common shares compared to the available limits in either equity program. The costs are reviewed for impairment and will be recorded to expense if and when the Company determines that future equity offerings are not probable of occurring or the Registration Statement and ATM are no longer available.
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). 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 for comparable debt instruments. The Company’s long-term 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 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. 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.

Summary of significant accoun16

Summary of significant accounting policies (Tables)	6 Months Ended
	Jun. 30, 2015
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 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. 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.

Cash, cash equivalents and ma17

Cash, cash equivalents and marketable securities (Tables)	6 Months Ended
	Jun. 30, 2015
Cash and Cash Equivalents [Abstract]
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): Total Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) June 30, 2015 Money Market funds, included in cash equivalents $ 49,009 $ 49,009 — — Marketable securities - U.S. treasuries 25,015 25,015 — — Total $ 74,024 $ 74,024 $ — $ — December 31, 2014 Money Market funds, included in cash equivalents $ 18,992 $ 18,992 — — Marketable securities - U.S. treasuries 27,021 27,021 — — Total $ 46,013 $ 46,013 $ — $ —
Schedule of marketable securities	Marketable securities at June 30, 2015 consist of the following (in thousands): Contracted Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value Current U.S. Treasuries 15-184 days $ 25,008 $ 7 $ — $ 25,015 Total $ 25,008 $ 7 $ — $ 25,015

Long-term debt (Tables)

Long-term debt (Tables)	6 Months Ended
	Jun. 30, 2015
Long-term Debt, Unclassified [Abstract]
Schedule of future principal payments on the new term loan	Future principal payments due on the 2014 Term Loan are as follows (in thousands): June 30, 2015 $ — 2016 2,223 2017 4,700 2018 5,058 2019 19 Total $ 12,000

Warrants (Tables)

Warrants (Tables)	6 Months Ended
	Jun. 30, 2015
Warrants and Rights Note Disclosure [Abstract]
Schedule of weighted average assumptions used to calculate the fair value of warrants	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, 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 %

Commitments and contingencies (

Commitments and contingencies (Tables)	6 Months Ended
	Jun. 30, 2015
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): June 30, 2015 2015 $ 675 2016 1,379 2017 231 Total $ 2,285

Common stock (Tables)

Common stock (Tables)	6 Months Ended
	Jun. 30, 2015
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): Six Months Ended June 30, 2015 2014 Warrants 78 4 Outstanding options 2,760 2,234 Total 2,838 2,238

Stock-based compensation (Table

Stock-based compensation (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, Six Months Ended June 30, 2015 2014 2015 2014 Research and development $ 450 $ 371 $ 865 $ 848 General and administrative 581 297 1,081 701 Total $ 1,031 $ 668 $ 1,946 $ 1,549
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- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at December 31, 2014 2,290 $ 7.26 8.08 $ 5,332 Granted 588 $ 9.31 Exercised (42 ) $ 2.38 Canceled (76 ) $ 15.61 Outstanding at June 30, 2015 2,760 $ 7.55 7.88 $ 18,061 Exercisable at June 30, 2015 1,248 $ 4.87 6.52 $ 11,372 Vested or expected to vest at June 30, 2015 2,611 $ 7.45 7.83 $ 17,345

Organization and operations (De

Organization and operations (Details)	6 Months Ended
	Jun. 30, 2015product
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of products in clinical development	2

Organization and operations (24

Organization and operations (Details 2) - USD ($) $ / shares in Units, $ in Thousands	Aug. 04, 2015	Mar. 17, 2015	Jun. 30, 2015	Jun. 30, 2014	May. 08, 2015	Mar. 02, 2015	Dec. 31, 2014
Underwritten public offering
Common stock, par value (in dollars per share)			$ 0.001				$ 0.001
Proceeds from sale of common stock, net of issuance costs			$ 48,369	$ 0
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)		6,272,726
Share price		$ 8.25
Proceeds from sale of common stock, net of issuance costs		$ 48,600
Offering expenses		$ 276
Over-allotment option
Underwritten public offering
Issuance of common stock (in shares)		818,181
Subsequent Event | Underwritten public offering
Underwritten public offering
Issuance of common stock (in shares)	3,850,000
Share price	$ 13
Proceeds from sale of common stock, net of issuance costs	$ 47,000
Offering expenses	$ 146
Subsequent Event | Over-allotment option
Underwritten public offering
Issuance of common stock (in shares)	577,500

Summary of significant accoun25

Summary of significant accounting policies (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
ASU 2015-03
New Accounting Pronouncement, Early Adoption [Line Items]
Unamortized debt issuance costs reclassified to carrying value of debt	$ 85	$ 99

Summary of significant accoun26

Summary of significant accounting policies (Details 2) $ in Thousands	Jun. 30, 2015USD ($)
Deferred public offering costs
Deferred offering costs	$ 293

Cash, cash equivalents and ma27

Cash, cash equivalents and marketable securities (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Quoted prices in active markets (Level 1)
Cash, cash equivalents and marketable securities
Money Market funds, included in cash equivalents	$ 49,009	$ 18,992
Total	74,024	46,013
U.S. Treasuries | Quoted prices in active markets (Level 1)
Cash, cash equivalents and marketable securities
Marketable securities - U.S. treasuries	25,015	27,021
Total
Cash, cash equivalents and marketable securities
Money Market funds, included in cash equivalents	49,009	18,992
Total	74,024	46,013
Total | U.S. Treasuries
Cash, cash equivalents and marketable securities
Marketable securities - U.S. treasuries	$ 25,015	$ 27,021

Cash, cash equivalents and ma28

Cash, cash equivalents and marketable securities (Details 2) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Marketable securities
Fair Value, Total	$ 25,015	$ 25,015	$ 27,021
U.S. Treasuries
Marketable securities
U.S. Treasuries (due 15-184 days) Amortized Cost	25,008	25,008
U.S. Treasuries (due 15-184 days) Unrealized Gains	7
U.S. Treasuries (due 15-184 days) Fair Value	25,015	25,015
Amortized Cost, Total	25,008	25,008
Unrealized Gains, Total	7
Fair Value, Total	$ 25,015	$ 25,015
U.S. Treasuries | Minimum
Marketable securities
Contracted Maturity - U.S. Treasuries (due 15-184 days)		15 days
U.S. Treasuries | Maximum
Marketable securities
Contracted Maturity - U.S. Treasuries (due 15-184 days)		184 days

Long-term debt (Details)

Long-term debt (Details)	Mar. 17, 2015USD ($)shares	Nov. 20, 2014USD ($)trancheinstallment$ / sharesshares	Jun. 30, 2015USD ($)shares	Dec. 31, 2014shares
Common stock
Long-Term Debt
Exercisable amount (in shares) | shares			77,603	77,603
Line of Credit | 2013 Term Loan
Long-Term Debt
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 | installment		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
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
Expired borrowing capacity			$ 5,000,000
Line of Credit | 2014 Term Loan, Second Tranche
Long-Term Debt
Debt financing		5,000,000
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) | shares		73,725	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
Subsequent private placement equity financings, amount		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	6,272,726
Financing costs allocated to additional paid-in capital	$ 276,000

Long-term debt (Details 2)

Long-term debt (Details 2)	Jun. 30, 2015USD ($)
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	$ 0
2014 Term Loan | Line of Credit
Future principal payments
2,016	2,223,000
2,017	4,700,000
2,018	5,058,000
2,019	19,000
Total	$ 12,000,000

Warrants (Details)

Warrants (Details) - shares	Jun. 30, 2015	Dec. 31, 2014	Nov. 20, 2014	Feb. 10, 2014
Common stock
Warrants
Warrants (in shares)	77,603	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	73,725

Warrants (Details 2)

Warrants (Details 2) - Hercules Technology Growth Capital, Inc. - Common stock - USD ($) $ / shares in Units, $ in Thousands	Nov. 20, 2014	Dec. 31, 2014
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) - shares	Apr. 23, 2014	Feb. 12, 2014	Feb. 10, 2014	Feb. 04, 2014	Jan. 29, 2014	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
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

Commitments and contingencies34

Commitments and contingencies (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,015	$ 675
2,016	1,379
2,017	231
Total	2,285
2012 Master Facilities Lease
Restricted cash related to facilities leases
Restricted cash	$ 316	$ 316

Commitments and contingencies35

Commitments and contingencies (Details 2) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Commitments and contingencies
Grant revenue		$ 115,000	$ 0	$ 236,000	$ 0
Bill and Melinda Gates Foundation
Commitments and contingencies
Grant revenue		115,000		236,000
Grant received	$ 1,200,000
Joint research collaboration agreement | Dana-Farber Cancer Institute and Harvard Medical School
Commitments and contingencies
Grant revenue		$ 9,000	$ 0	$ 30,000	$ 0

Commitments and contingencies36

Commitments and contingencies (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Commitments and contingencies
Amount expensed related to supply agreements	$ 6,969	$ 4,551	$ 15,478	$ 8,958
Supply agreement | Fujifilm
Commitments and contingencies
Amount expensed related to supply agreements	$ 1,100	$ 412	$ 3,600	$ 437

Common stock (Details)

Common stock (Details)	Jan. 20, 2014	Jun. 30, 2015$ / sharesshares	Jun. 30, 2014shares	Dec. 31, 2014$ / sharesshares	Dec. 31, 2013shares
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		24,204,463		17,869,235
Common stock, shares outstanding		24,191,511		17,852,389
Reverse stock split	0.0840
Earnings Per Share, Diluted [Abstract]
Common stock equivalents (in shares)		2,838,000	2,238,000
Outstanding options
Common stock
Options exercised (in shares)		42,000
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		12,952		16,840
Director | Outstanding options
Common stock
Options exercised (in shares)					31,092
Warrants
Earnings Per Share, Diluted [Abstract]
Common stock equivalents (in shares)		78,000	4,000
Outstanding options
Earnings Per Share, Diluted [Abstract]
Common stock equivalents (in shares)		2,760,000	2,234,000

Stock-based compensation (Detai

Stock-based compensation (Details) - shares	Jan. 01, 2015	Jun. 30, 2015
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
Number of shares available for grant		284,913
Common shares that may be issued		3,044,717

Stock-based compensation (Det39

Stock-based compensation (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Stock Based Compensation Expense
Stock-based compensation expense	$ 1,031	$ 668	$ 1,946	$ 1,549
Research and development
Stock Based Compensation Expense
Stock-based compensation expense	450	371	865	848
General and administrative
Stock Based Compensation Expense
Stock-based compensation expense	$ 581	$ 297	$ 1,081	$ 701

Stock-based compensation (Det40

Stock-based compensation (Details 3) - Outstanding options - USD ($) $ / shares in Units, shares in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Shares
Outstanding at the beginning of the period (in shares)	2,290
Granted (in shares)	588
Exercised (in shares)	(42)
Canceled (in shares)	(76)
Outstanding at the end of the period (in shares)	2,760	2,290
Exercisable at the end of the period (in shares)	1,248
Vested or expected to vest at the end of the period (in shares)	2,611
Weighted - Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 7.26
Granted (in dollars per share)	9.31
Exercised (in dollars per share)	2.38
Canceled (in dollars per share)	15.61
Outstanding at the end of the period (in dollars per share)	7.55	$ 7.26
Exercisable at the end of the period (in dollars per share)	4.87
Vested or expected to vest at the end of the period (in dollars per share)	$ 7.45
Weighted- Average Remaining Contractual Term
Outstanding at the beginning/end of the period	7 years 10 months 17 days	8 years 29 days
Exercisable at the end of the period	6 years 6 months 7 days
Vested or expected to vest at the end of the period	7 years 9 months 29 days
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars)	$ 18,061	$ 5,332
Exercisable at the end of the period (in dollars)	11,372
Vested or expected to vest at the end of the period (in dollars)	$ 17,345

Stock-based compensation (Det41

Stock-based compensation (Details 4) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Additional disclosures
Stock-based compensation expense	$ 1,031,000	$ 668,000		$ 1,946,000	$ 1,549,000
Performance-based stock options
Additional disclosures
Stock-based compensation expense	$ 0	0		$ 0	435,000
Number of options probable to achieve performance-based milestones			96,988
Options outstanding (in shares)	56,336			56,336
Employee stock purchase plan | 2014 ESPP
Additional disclosures
Stock-based compensation expense	$ 26,000	$ 0		$ 53,000	$ 0
Number of shares of common stock authorized under the plan	200,776			200,776
Option period				6 months
Number of shares issued				15,622
Shares remaining for future issuance (in shares)	165,085			165,085