Genocea Biosciences (GNCAQ) 10-Q 25 Jul 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 24, 2019
Document and Entity Information
Entity Registrant Name	GENOCEA BIOSCIENCES, INC.
Entity Central Index Key	0001457612
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		26,149,689
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Small Business	true
Entity Ex Transition Period	true

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Operating Lease, Liability, Current	$ 1,045	$ 0
Current assets:
Cash and cash equivalents	58,670	26,361
Prepaid expenses and other current assets	1,062	696
Total current assets	59,732	27,057
Property and equipment, net	2,813	2,582
Operating Lease, Right-of-Use Asset	6,840	0
Restricted cash	316	316
Other non-current assets	1,061	1,160
Total assets	70,762	31,115
Current liabilities:
Accounts payable	1,247	1,659
Accrued expenses and other current liabilities	5,050	3,816
Current portion of long-term debt	2,673	5,257
Total current liabilities	10,015	10,732
Non-current liabilities:
Long-term debt, net of current portion and discount	11,059	9,565
Operating lease liabilities, net of current portion	5,861
Other non-current liabilities	0	11
Total liabilities	32,324	23,780
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock	701	701
Common stock	26	11
Additional paid-in capital	351,777	298,627
Accumulated deficit	(314,066)	(292,004)
Total stockholders’ equity	38,438	7,335
Total liabilities and stockholders’ equity	$ 70,762	$ 31,115

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating expenses:
Research and development	$ 6,849	$ 5,316	$ 13,309	$ 12,591
General and administrative	3,217	4,472	6,234	7,581
Total operating expenses	10,066	9,788	19,543	20,172
Loss from operations	(10,066)	(9,788)	(19,543)	(20,172)
Other income (expense):
Interest expense, net	(299)	(241)	(601)	(442)
Other income (expense)	0	93	(1)	87
Total other income (expense)	3,571	5,350	(2,519)	(156)
Net loss	(6,495)	(4,438)	(22,062)	(20,328)
Comprehensive loss	$ (6,495)	$ (4,438)	$ (22,062)	$ (20,328)
Net loss per share - basic and diluted (in dollars per share)	$ (0.42)	$ (0.42)	$ (1.57)	$ (2.07)
Weighted-average number of common shares used in computing net loss per share (in shares)	15,344	10,693	14,035	9,804

Consolidated Consolidated State

Consolidated Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Preferred Shares	Additional Paid-In Capital	Accumulated Deficit	ESPP	ESPPCommon Stock	ESPPAdditional Paid-In Capital
Balance - Stockholders' Equity (Deficit) at Dec. 31, 2017	$ (6,050)	$ 3		$ 258,140	$ (264,193)
Balance - Stockholders' Equity (Deficit) (in shares) at Dec. 31, 2017		3,592	0
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity
Issuance of common stock	35,864	$ 7		35,156
Issuance of common stock (in shares)		6,790	701
Stock-based compensation expense	644			644
Net loss	(15,890)				(15,890)
Balance - Stockholders' Equity (Deficit) at Mar. 31, 2018	14,568	$ 10		293,940	(280,083)
Balance - Stockholders' Equity (Deficit) (in shares) at Mar. 31, 2018		10,382	701
Balance - Stockholders' Equity (Deficit) at Dec. 31, 2017	(6,050)	$ 3		258,140	(264,193)
Balance - Stockholders' Equity (Deficit) (in shares) at Dec. 31, 2017		3,592	0
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity
Net loss	(20,328)
Balance - Stockholders' Equity (Deficit) at Jun. 30, 2018	13,865	$ 11		297,674	(284,521)
Balance - Stockholders' Equity (Deficit) (in shares) at Jun. 30, 2018		10,828	701
Balance - Stockholders' Equity (Deficit) at Mar. 31, 2018	14,568	$ 10		293,940	(280,083)
Balance - Stockholders' Equity (Deficit) (in shares) at Mar. 31, 2018		10,382	701
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity
Issuance of common stock	2,922	$ 1		2,921		$ 31		$ 31
Adjustments to Additional Paid in Capital, Warrant Issued	190			190
Issuance of common stock (in shares)		440					6
Stock-based compensation expense	592			592
Net loss	(4,438)				(4,438)
Balance - Stockholders' Equity (Deficit) at Jun. 30, 2018	13,865	$ 11		297,674	(284,521)
Balance - Stockholders' Equity (Deficit) (in shares) at Jun. 30, 2018		10,828	701
Balance - Stockholders' Equity (Deficit) at Dec. 31, 2018	7,335	$ 11		298,627	(292,004)
Balance - Stockholders' Equity (Deficit) (in shares) at Dec. 31, 2018		10,847	701
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity
Issuance of common stock	14,026	$ 3		14,023
Issuance of common stock (in shares)		3,200
Exercise of stock options	12			12
Exercise of stock options (in shares)		3
Stock-based compensation expense	429			429
Net loss	(15,567)				(15,567)
Balance - Stockholders' Equity (Deficit) at Mar. 31, 2019	6,235	$ 14		313,091	(307,571)
Balance - Stockholders' Equity (Deficit) (in shares) at Mar. 31, 2019		14,050	701
Balance - Stockholders' Equity (Deficit) at Dec. 31, 2018	7,335	$ 11		298,627	(292,004)
Balance - Stockholders' Equity (Deficit) (in shares) at Dec. 31, 2018		10,847	701
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity
Net loss	(22,062)
Balance - Stockholders' Equity (Deficit) at Jun. 30, 2019	38,438	$ 26		351,777	(314,066)
Balance - Stockholders' Equity (Deficit) (in shares) at Jun. 30, 2019		26,150	701
Balance - Stockholders' Equity (Deficit) at Mar. 31, 2019	6,235	$ 14		313,091	(307,571)
Balance - Stockholders' Equity (Deficit) (in shares) at Mar. 31, 2019		14,050	701
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity
Issuance of common stock	38,167	$ 12		38,155		$ 48		$ 48
Issuance of common stock (in shares)		12,074					24
Exercise of stock options	9			9
Exercise of stock options (in shares)		2
Stock-based compensation expense	474			474
Net loss	(6,495)				(6,495)
Balance - Stockholders' Equity (Deficit) at Jun. 30, 2019	$ 38,438	$ 26		$ 351,777	$ (314,066)
Balance - Stockholders' Equity (Deficit) (in shares) at Jun. 30, 2019		26,150	701

Condensed Consolidated Statemen

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities
Net loss	$ (22,062)	$ (20,328)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	550	543
Stock-based compensation	902	1,236
Allocation of proceeds to transaction expenses	0	2,115
Change in fair value of warrant liability	1,917	(2,315)
Gain on sale of equipment	(19)	(50)
Write-off of deferred financing fees	0	355
Non-cash interest expense	41	291
Changes in operating assets and liabilities	729	(5,222)
Net cash used in operating activities	(17,942)	(23,375)
Investing activities
Purchases of property and equipment	(654)	(174)
Proceeds from sale of equipment	19	72
Net cash used in investing activities	(635)	(102)
Financing activities
Proceeds from equity offerings, net	0	2,920
Proceeds from issuance of common stock, net	52,194	52,538
Payment of deferred financing costs	0	(127)
Proceeds from long-term debt	0	592
Repayment of long-term debt	(1,377)	(535)
Proceeds from exercise of stock options	21	0
Proceeds from the issuance of common stock under ESPP	48	31
Net cash provided by financing activities	50,886	55,419
Net increase in cash and cash equivalents	32,309	31,942
Cash, cash equivalents and restricted cash at beginning of period	26,677	12,589
Cash, cash equivalents and restricted cash at end of period	58,986	44,531
Supplemental cash flow information
Cash paid for interest	577	508
Property and equipment included in accounts payable and accrued expenses	127	0
Reclassification of warrants to additional paid-in capital	$ 0	$ 190

Organization and operations

Organization and operations	6 Months Ended
	Jun. 30, 2019
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 cancer immunotherapies using its ATLAS TM proprietary discovery platform. The ATLAS platform profiles each patient's CD4 + and CD8 + T cell immune responses to every potential target or "antigen" in that patient's tumor. Genocea believes that this approach optimizes antigen selection for cancer vaccines and cellular therapies, because it identifies antigens to which a patient’s T cells already mount anti-tumor responses. The Company believes that ATLAS could lead to more immunogenic and efficacious cancer immunotherapies. The Company’s most advanced program is GEN-009, a personalized neoantigen cancer vaccine, for which it is conducting a Phase 1/2a clinical trial. The GEN-009 program uses ATLAS to identify neoantigens, or immunogenic tumor mutations unique to each patient, for inclusion in each patient's GEN-009 vaccine. The Company is also advancing GEN-011, a neoantigen-specific adoptive T cell therapy program, as well as GEN-010, a follow-on neoantigen vaccine program. 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 early clinical stage companies, including dependence on key individuals, competition from other companies, the need and related uncertainty associated to 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 the uncertainty of success of its preclinical and clinical trials, dependence on third parties, the need to obtain additional financing, dependence on key individuals, regulatory approval of products, uncertainty of market acceptance of products, competition from companies with greater financial, technological and other resources, compliance with government regulations, protection of proprietary technology, and product liability. The Company has historical losses from operations and anticipates that it will continue to incur significant operating losses for the foreseeable future as it continues to develop its product candidates. Effective May 22, 2019, the Company effected a reverse stock split of its issued and outstanding common stock, par value $0.001, at a ratio of one-for-eight, and decreased the number of authorized shares of common stock from 250,000,000 shares to 85,000,000 shares. The share and per share information presented in these financial statements and related notes have been retroactively adjusted to reflect the one-for-eight reverse stock split. Operating Capital Requirements Under Accounting Standards Update ("ASU"), 2014-15, Presentation of Financial Statements-Going Concern (Subtopic 205-40), also referred to as Accounting Standards Codification ("ASC") 205-40 (“ASC 205-40”), the Company has the responsibility to evaluate whether conditions and/or events raise substantial doubt about its ability to meet its future financial obligations as they become due within one year after the date that the financial statements are issued. As required by ASC 205-40, this evaluation shall initially not take into consideration the potential mitigating effects of plans that have not been fully implemented as of the date the financial statements are issued. Management has assessed the Company’s ability to continue as a going concern in accordance with the requirement of ASC 205-40. As reflected in the condensed consolidated financial statements, the Company had available cash and cash equivalents of $58.7 million at June 30, 2019 . The Company believes that its cash, cash equivalents and investments will fund its operations into the first quarter of 2021. The Company plans to continue to fund its operations through public or private equity offerings, strategic transactions, proceeds from sales of its common stock under its at-the-market equity offering program, or by other means. However, adequate additional financing may not be available to the Company on acceptable terms, or at all. If the Company is unable to raise capital when needed, or on attractive terms, it may be forced to implement cost reduction strategies, including ceasing development of GEN-009, GEN-011, and other corporate programs and activities.

Summary of significant accounti

Summary of significant accounting policies	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies Basis of presentation In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting of normal recurring accruals necessary for a fair presentation of the Company’s financial statements for interim periods in accordance with accounting principles generally accepted in the United States (U.S. GAAP). We operate as one operating segment, which is discovering, researching and developing novel cancer immunotherapies. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with our audited consolidated financial statements and the accompanying notes included in our Annual Report on Form 10-K for the year ended December 31, 2018 (“2018 Form 10-K”). Our accounting policies are described in the “Notes to Consolidated Financial Statements” in our 2018 Form 10-K and updated, as necessary, in our Quarterly Reports on Form 10-Q. The December 31, 2018 condensed consolidated balance sheet data presented for comparative purposes was derived from our audited financial statements, but does not include all disclosures required by U.S. GAAP. The results of operations for the three and six months ended June 30, 2019 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period. Use of Estimates The preparation of financial statements in conformity with U.S. 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 clinical trial accruals, estimates related to prepaid and accrued research and development expenses, stock-based compensation expense, and warrants to purchase redeemable securities. 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. Summary of Significant Accounting Policies There were no changes to significant accounting policies during the six months ended June 30, 2019 , as compared to the those identified in the 2018 Form 10-K, except for the Company's adoption of ASC Topic 842, Leases on January 1, 2019. The following is the Company's new accounting policy for leases. Leases At the inception of the contract, the Company determines if an arrangement is a lease and has a lease term greater than 12 months. Leases that are concluded to be operating leases are included in operating lease right-of-use (“ROU”) assets and operating lease liabilities in the consolidated balance sheets. Leases that are concluded to be finance leases are included in property and equipment and other current liabilities in the consolidated balance sheets. ROU assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent the Company's obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As most of the Company's leases do not provide an implicit rate, the Company uses an estimate of its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. The Company uses the implicit rate when readily determinable. The operating lease ROU asset is reduced by deferred lease payments and unamortized lease incentives. The Company's lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components, which are generally accounted for separately. The non-lease components generally consist of common area maintenance that is expensed as incurred. Recently adopted accounting standards Standard Description Effect on the financial statements ASU No. 2016-02, Leases (Topic 842) In February 2016, the FASB established ASC Topic 842, Leases , (ASC 842) by issuing ASU No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use model ("ROU") that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases are classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The Company adopted ASC 842 effective January 1, 2019. The adoption of ASC 842 resulted in the Company recognizing ROU assets and related operating lease liabilities of $1.7 million and $1.8 million, respectively, in our condensed consolidated balance sheet as of January 1, 2019. The Company used the modified retrospective method of adoption, with January 1, 2019 as the effective date of initial application. The Company elected the short-term lease recognition exemption for all leases that qualify. The Company elected the package of practical expedients for leases that commenced prior to January 1, 2019, allowing it not to reassess (i) whether any expired or existing contracts contain leases, (ii) the lease classification for any expired or existing leases and (iii) the initial indirect costs for any existing leases. ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. The new standard largely aligns the accounting for share-based payment awards issued to employees and nonemployees by expanding the scope of ASC 718 to apply to nonemployee share-based transactions, as long as the transaction is not effectively a form of financing. The Company adopted ASU No. 2018-07 effective January 1, 2019. The adoption of ASU No. 2018-07 did not have a material impact on the Company's condensed consolidated financial statements. Recently issued accounting standards Standard Description Effect on the financial statements ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables and available-for-sale debt securities. The new guidance will be effective for the Company beginning in the first quarter of 2020, with early adoption permitted. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements. ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement which requires public entities to disclose certain new information and modifies some disclosure requirements. The new guidance will be effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements. ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. In August 2018, the FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and recognize as an asset. The new guidance will be effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2019. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements.

Fair value of financial instrum

Fair value of financial instruments	6 Months Ended
	Jun. 30, 2019
Cash and Cash Equivalents [Abstract]
Fair value of financial instruments	The Company has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. • Level 1 - Fair values are determined by utilizing quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access; • Level 2 - Fair values are determined by utilizing quoted prices for similar assets and liabilities in active markets or other market observable inputs such as interest rates, yield curves and foreign currency spot rates; and • Level 3 - Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. The Company's financial assets consist of cash equivalents and the Company's financial liabilities consist of warrant liability. The fair value of the Company’s cash equivalents is determined using quoted prices in active markets. Our cash equivalents consist of money market funds. The Company’s cash equivalents have been classified as Level 1. The fair value of the Company’s warrant liability is determined using a Monte Carlo simulation. See Note 7. Warrants . The assumptions used in calculating the estimated fair value of the warrants represent the Company’s best estimates and include probabilities of settlement scenarios, future changes in the Company’s stock price, risk-free interest rates, volatility and probability of the Company being acquired. The estimates are based, in part, on subjective assumptions and could differ materially in the future. The Company’s warrant liability has been classified as Level 3. Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Total (Level 1) (Level 2) (Level 3) June 30, 2019 Assets: Cash equivalents $ 19,802 $ 19,802 $ — $ — Total assets $ 19,802 $ 19,802 $ — $ — Liabilities: Warrant liability $ 5,389 $ — $ — $ 5,389 Total liabilities $ 5,389 $ — $ — $ 5,389 December 31, 2018 Assets: Cash equivalents $ 24,651 $ 24,651 $ — $ — Total assets $ 24,651 $ 24,651 $ — $ — Liabilities: Warrant liability $ 3,472 $ — $ — $ 3,472 Total liabilities $ 3,472 $ — $ — $ 3,472 The following table reflects the change in the Company’s Level 3 warrant liability from December 31, 2018 through June 30, 2019 : Warrant Liability Balance at December 31, 2018 $ 3,472 Change in fair value 1,917 Balance at June 30, 2019 $ 5,389

Accrued expenses and other curr

Accrued expenses and other current liabilities	6 Months Ended
	Jun. 30, 2019
Payables and Accruals [Abstract]
Accrued expenses and other current liabilities	Accrued expenses and other current liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): June 30, December 31, 2019 2018 Research and development $ 1,462 $ 759 Payroll and employee-related 1,491 2,147 Other current liabilities 2,097 910 Total $ 5,050 $ 3,816

Long-term debt

Long-term debt	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Long-term debt	Long-term debt In Q2 2018, the Company entered into an amended and restated loan and security agreement (the “2018 Term Loan”) with Hercules Capital, Inc. (“Hercules”), which provided a $14.0 million term loan. The 2018 Term Loan will mature on May 1, 2021 and accrues interest at a floating rate per annum equal to the greater of (i) 7.75% or (ii) the sum of 2.75% plus the prime rate. The 2018 Loan Agreement provided for interest-only payments until June 1, 2019. Since the Company met certain performance milestones, interest-only payments have been extended until June 1, 2020. Thereafter, payments will include equal installments of principal and interest through maturity. The 2018 Term Loan may be prepaid subject to a prepayment charge. The Company is obligated to pay an additional end of term charge of 6.7%. The 2018 Term Loan is secured by a lien on substantially all assets of the Company, other than intellectual property. Hercules has a perfected first-priority security interest in certain cash, cash equivalents and investment accounts. The 2018 Term Loan contains non-financial covenants, representations and a (“Material Adverse Effect”) provision. There are no financial covenants. 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 documents, 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 a Material Adverse Effect 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. As of June 30, 2019 , the Company was in compliance with all covenants of the 2018 Term Loan. The 2018 Term Loan is automatically redeemable upon a change in control. The Company believes acceleration of the repayment of amounts outstanding under the loan is remote, and therefore the debt balance is classified according to the contractual payment terms at June 30, 2019 . In connection with a previously issued term loan in 2014 and the 2018 Term Loan, the Company issued common stock warrants to Hercules (the “First Warrant and Second Warrant”, respectively). See Note 7. Warrants . As of June 30, 2019 and December 31, 2018 , the Company had outstanding borrowings of $13.7 million and $14.8 million , respectively. Interest expense was $0.4 million for each of the three months ended June 30, 2019 and 2018 and $0.9 million and $0.8 million for the six months ended June 30, 2019 and 2018 , respectively. At June 30, 2019 , the 2018 Term Loan bears an effective interest rate of 11.4% . Future principal payments, including the End of Term Charges, are as follows (in thousands): June 30, 2019 2019 $ 542 2020 7,399 2021 6,462 Total $ 14,403 The Company's balance sheet classification has been updated to reflect the extension of interest only payments.

Stockholders' equity

Stockholders' equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Stockholders' equity	Stockholders' equity As of June 30, 2019 , the Company has authorized 85,000,000 shares of common stock at $0.001 par value per share and 25,000,000 shares of preferred stock at $0.001 par value per share. As of June 30, 2019 , 26,149,689 shares of common stock and 1,635 shares of preferred stock were issued and outstanding. As of December 31, 2018 , 10,846,397 shares of common stock were issued and outstanding and 1,635 shares of preferred stock were issued and outstanding. 2019 Public Offering On June 21, 2019, the Company entered into an underwriting agreement relating to the underwritten public offering of 10,500,000 shares of the Company’s common stock, par value $0.001 per share, at a price to the public of $3.50 per share, for gross proceeds of approximately $36.8 million (the “2019 Public Offering”). Under the terms of the underwriting agreement for the 2019 Public Offering, the Company also granted the underwriters an option to purchase up to an additional 1,575,000 shares of common stock (“Overallotment Option”). On June 26, 2019, the underwriters exercised this option in full. The Company received approximately $5.5 million in gross proceeds from the underwriter’s exercise of the Overallotment Option. In connection with the 2019 Public Offering, inclusive of the Overallotment Option, the Company incurred approximately $3.9 million of offering-related expenses, resulting in total net proceeds of $38.4 million . Private Placement In February 2019, the Company completed a private placement financing transaction (the “Private Placement”). The Company issued 3,199,998 shares (the “Shares”) of common stock, prefunded warrants (the “Pre-Funded Warrants”) to purchase 531,250 shares of common stock (the “Pre-Funded Warrant Shares”), and warrants (the “Private Placement Warrants”) to purchase up to 932,812 shares of common stock (the “Warrant Shares”). The Shares, Pre-Funded Warrants and Private Placement Warrants (collectively, the “Units”) were sold at a purchase price of $4.02 per Unit. The Company received net cash proceeds of approximately $13.8 million for the purchase of the Shares, Pre-Funded Warrant Shares and Warrant Shares. See Note 7. Warrants . The Company had the option to issue additional shares of common stock in a second closing (the “Second Closing”) for gross proceeds of up to $24.2 million . The occurrence of the Second Closing was conditioned on top-line results from Part A of our Phase 1/2a clinical trial for GEN-009 and a decision by our board of directors to proceed with the Second Closing. In June 2019, the Company announced top-line results from this trial but elected not to proceed with the Second Closing. In lieu of the Second Closing the Company proceeded with the 2019 Public Offering. 2018 Public Offering In January 2018, the Company entered into two underwriting agreements, the first relating to the underwritten public offering of 6,670,625 shares of the Company’s common stock, par value $0.001 per share, and accompanying warrants to purchase up to 3,335,313 shares of common stock (“2018 Public Offering Warrants”), at a combined price of $8.00 per share, for gross proceeds of approximately $53.4 million (the “2018 Common Stock Offering”) and the second relating to the underwritten public offering of 1,635 shares of the Company’s Series A convertible preferred stock, par value $0.001 per share, which are convertible into 204,375 shares of common stock, and accompanying warrants to purchase up to 102,188 shares of common stock for gross proceeds of approximately $1.6 million (the “Preferred Stock Offering,” and together with the 2018 Common Stock Offering, the “January 2018 Financing”). The Company also granted the underwriters an Overallotment Option ("Overallotment Option") to purchase up to an additional 1,000,594 shares of common stock and/or additional warrants to purchase up to 500,297 shares of common stock. The underwriters exercised their Overallotment Option and acquired additional warrants to purchase up to 299,475 shares of common stock. Preferred Stock Each share of preferred stock is convertible at any time at the option of the holder, provided that the holder will be prohibited from converting the preferred stock into shares of common stock if, as a result of such conversion, the holder, together with its affiliates, would own more than 9.99% of the total number of shares of common stock then issued and outstanding. Each share of preferred stock is convertible into 125 shares of common stock, subject to certain adjustments upon stock dividends and stock splits. The preferred stock ranks pari passu on an as-converted to common stock basis with the common stock as to distributions of assets upon the Company’s liquidation, dissolution or winding up, whether voluntarily or involuntarily, or a “Fundamental Transaction,” as defined in the Certificate of Designation. Shares of preferred stock have no voting rights, except as required by law and except that the consent of the holders of a majority of the outstanding preferred stock is required to amend the terms of the preferred stock. The holders of preferred stock shall be entitled to receive dividends in the same form as dividends actually paid on shares of common stock when, as and if such dividends are declared and paid on shares of the common stock, on an as-if-converted-to-common stock basis. The Company determined that the preferred stock should be equity classified in accordance with ASC 480, Distinguishing Liabilities from Equity (“ASC 480”) for the periods ended June 30, 2019 and December 31, 2018 , respectively. For the six months ended June 30, 2018, the Company recorded $0.3 million in additional paid-in capital as a result of the preferred stock’s beneficial conversion feature. Issuance Costs In connection with the January 2018 Financing, the Company incurred approximately $4.0 million of issuance costs. The Company allocated approximately $2.6 million of the issuance costs to the common and preferred stock, and recorded these amounts within additional paid-in capital, and approximately $1.4 million of the issuance costs to the 2018 Public Offering Warrants. As the 2018 Public Offering Warrants were classified as liabilities, the Company immediately expensed the issuance costs allocated to the 2018 Public Offering Warrants in the three months ended March 31, 2018. Warrants See Note 7. Warrants. Hercules In connection with the 2018 Loan Agreement with Hercules, see Note 5. Long-term debt , the Company also entered into an amendment to the November 2014 equity rights letter agreement (the “Amended 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 Amended Equity Rights Letter Agreement 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, or (b) the expiration or termination of the exercise period for the Second Warrant. See Note 7. Warrants . At-the-market equity offering program In 2015, the Company entered into an agreement, as amended, with Cowen and Company, LLC to establish an at-the-market equity offering program (“ATM”) pursuant to which it was able to offer and sell up to $50 million of its common stock at prevailing market prices from time to time. Through June 30, 2019 , the Company has sold an aggregate of approximately 0.5 million shares under the ATM and received approximately $4.0 million in net proceeds after deducting commissions.

Warrants (Notes)

Warrants (Notes)	6 Months Ended
	Jun. 30, 2019
Warrants [Abstract]
Schedule of Product Warranty Liability [Table Text Block]	Warrants As of June 30, 2019 , the Company had the following potentially issuable shares of common stock related to unexercised warrants outstanding: Shares Exercise price Expiration date Classification First Warrant 9,216 $ 65.92 Q4 2019 Equity Second Warrant 41,177 $ 6.80 Q2 2023 Equity 2018 Public Offering Warrants 3,616,944 $ 9.60 Q1 2023 Liability Private Placement Warrants 932,812 $ 4.52 Q1 2024 Equity Pre-Funded Warrants 531,250 $ 0.08 Q1 2039 Equity 5,131,399 First and Second Warrant 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 Company determined that the First and Second Warrant should be equity classified in accordance with ASC 480 for all periods presented. 2018 Public Offering Warrants 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. In the event of an “Acquisition,” defined generally to include a merger or consolidation resulting in the sale of 50% or more of the voting securities of the Company, the sale of all, or substantially all, of the assets or voting securities of the Company, or other change of control transaction, as defined in the 2018 Public Offering Warrants, the Company will be obligated to use its best efforts to ensure that the holders of the 2018 Public Offering Warrants receive new warrants from the surviving or acquiring entity (the “Acquirer”). The new warrants to purchase shares in the Acquirer shall have the same expiration date as the 2018 Public Offering Warrants and a strike price that is based on the proportion of the value of the Acquirer’s stock to the Company’s common stock. If the Company is unable, despite its best efforts, to cause the Acquirer to issue new warrants in the Acquisition as described above, then, if the Company’s stockholders are to receive cash in the Acquisition, the Company will settle the 2018 Public Offering Warrants in cash and if the Company’s stockholders are to receive stock in the Acquisition, the Company will issue shares of its common stock to each Warrant holder. The Company determined that the 2018 Public Offering Warrants should be liability classified in accordance with ASC 480. As the 2018 Public Offering Warrants are liability-classified, the Company remeasures the fair value of the Warrants at each reporting date. The Company initially recorded the 2018 Public Offering Warrants at their estimated fair value of approximately $18.2 million . In connection with the Company's remeasurement of the 2018 Public Offering Warrants to fair value, the Company recorded income of approximately $3.9 million and $5.5 million for the three months ended June 30, 2019 and 2018 , respectively, and expense of $1.9 million and $2.3 million of income for the six months ended June 30, 2019 and June 30, 2018 , respectively. The fair value of the warrant liability is approximately $5.4 million and $3.5 million as of June 30, 2019 and December 31, 2018 , respectively. See Note 3. Fair Value Measurements. The following table details the assumptions used in the Monte Carlo simulation models used to estimate the fair value of the Warrant Liability as of June 30, 2019 and December 31, 2018 , respectively: June 30, 2019 December 31, 2018 Stock price $ 3.92 $ 2.32 Volatility 121.5 % 111.3 % Remaining term (years) 3.6 4.1 Expected dividend yield — — Risk-free rate 1.7 % 2.4%-2.5% Range of annual acquisition event probability 15.0%-30.0% 0.0%-30.0% Private Placement and Prefunded Warrants The exercise price of the warrants is subject to appropriate adjustment in the event of stock dividends, subdivisions, stock splits, stock combinations, reclassifications, reorganizations or a change of control affecting our common stock. The Company determined that the Private Placement Warrants and the Pre-Funded Warrants should be equity classified in accordance with ASC 480 for the period ended June 30, 2019 . The Company also determined that the Pre-Funded Warrants should be included in the determination of basic earnings per share in accordance with ASC 260, Earnings per Share .

Stock and employee benefit plan

Stock and employee benefit plans	6 Months Ended
	Jun. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock and employee benefit plans	Stock and employee benefit plans Stock-based compensation expense Total stock-based compensation expense is recognized for stock options and restricted stock awards granted to employees and non-employees and has been reported in the Company’s condensed consolidated statements of operations as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development $ 170 $ 159 $ 352 $ 300 General and administrative 304 433 551 936 Total $ 474 $ 592 $ 903 $ 1,236 Stock options The following table summarizes stock option activity for employees and non-employees (shares in thousands): Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2018 893 $ 18.79 $ — Granted 501 $ 4.66 Exercised (5 ) $ 4.32 Cancelled (104 ) $ 25.24 Outstanding at June 30, 2019 1,285 $ 12.81 8.32 $ 1,435 Exercisable at June 30, 2019 402 $ 25.57 6.38 $ — Performance-based awards The Company granted stock awards 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, 2019 , and did not recognize stock-based compensation expense for this period. As of June 30, 2019 , there were 7,042 performance-based common stock awards outstanding for which the probability of achievement was not deemed probable. Employee stock purchase plan On February 10, 2014, the Company’s board of directors adopted the 2014 Employee Stock Purchase Plan (the “2014 ESPP”). The 2014 ESPP, as amended, authorizes the issuance of up to 337,597 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 stock-based compensation expense related to the 2014 ESPP was insignificant for the three and six months ended June 30, 2019 and 2018 , respectively.

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Lease commitments In May 2019, the Company entered into a lease extension for office and laboratory space through February 2025. The Company also has a lease for additional office space through February 2020. The right to use asset and lease liability were calculated using an incremental borrowing rate of 8.25% and 10% , respectively. For the three months ended June 30, 2019 and 2018 rent expense was $0.3 million and $0.4 million , respectively. For the six months ended June 30, 2019 and 2018 rent expense was $0.7 million and $0.8 million , respectively. In March 2019, the Company entered into a sublease agreement for a portion of the office space lease through February 2020. Since the Company retained its obligations under the sublease, it did not adjust the lease liability, however the sublease is being reflected as a reduction of lease expense. Maturities of lease liabilities are as follows (in thousands): June 30, 2019 2019 $ 821 2020 1,477 2021 1,474 2022 1,510 2023 and thereafter 3,401 Total lease payments 8,683 Less imputed interest (1,777 ) Total $ 6,906 At June 30, 2019 and December 31, 2018 , the Company has an outstanding letter of credit of $0.3 million with a financial institution related to a security deposit for the office and lab space lease, which is secured by cash on deposit and expires on February 28, 2025. Litigation Pending Litigation: Emerson v. Genocea Biosciences et al. , U.S. District Court (Mass.), Civil Action No. 17-cv-12137-PBS (the “ Emerson Action”). In 2017, three purported shareholders filed placeholder complaints against Genocea and certain of its officers alleging violations of the federal securities laws in connection with the Company’s disclosures related to GEN-003, a Phase 3-ready investigational immunotherapy for the treatment of genital herpes infections. On February 12, 2018, the Court appointed the Genocea Investor Group (a group of five purported shareholders) as lead plaintiff in the consolidated proposed class action, and appointed Scott+Scott LLP, Levi & Korsinsky LLP, and Block & Leviton LLP as lead counsel. The lead plaintiff filed an amended complaint on March 29, 2018. Defendants filed a motion to dismiss on May 14, 2018. The lead plaintiff filed an opposition to defendants’ motion to dismiss on June 28, 2018, as well as a motion to strike certain documents attached to defendants’ motion to dismiss, on June 29, 2018. Defendants filed a reply in further support of the dismissal motion, and an opposition to plaintiffs’ motion to strike, on July 30, 2018. The court held oral argument on the motion to dismiss and motion to strike on September 25, 2018. On December 6, 2018, the court granted defendants’ motion to dismiss and, because the court’s decision did not consider the documents plaintiffs sought to strike, did not rule on plaintiffs’ motion to strike. On January 7, 2019, plaintiffs filed a notice of appeal in the District of Massachusetts to appeal the court’s order granting defendants’ motion to dismiss. The appeal, captioned Yuksel v. Genocea Biosciences, Inc., et al. , U.S. Court of Appeal for the First Circuit, Case No. 19-1036, was docketed in the First Circuit on January 15, 2019. By order dated January 29, 2019, the First Circuit set a deadline of March 11, 2019 for plaintiffs’ opening brief. Shortly thereafter, however, plaintiffs made a settlement offer to defendants, and the parties subsequently entered into a settlement agreement and general release on April 22, 2019. In connection with the settlement agreement, the parties fully and finally resolved the Emerson Action, including the entry of a general release, and plaintiffs agreed to request a voluntary dismissal of the appeal with prejudice pursuant to Federal Rule of Appellate Procedure 42(b). On May 9, 2019, plaintiffs filed the voluntarily dismissal motion. The Court dismissed the Emerson Action on May 23, 2019. Kahr v. William Clark et al. , U.S. District Court (Del.), Civil Action No. 18-cv-00186-MN. On January 31, 2018, Barry Kahr, a purported Genocea shareholder, filed a putative shareholder derivative complaint against certain of the Company’s officers and directors (including certain former officers and directors), naming the Company as the nominal defendant. The complaint alleged violations of the Securities Exchange Act of 1934, as amended, and Rule 14a-9 in connection with disclosures made in the Company’s Schedule 14A Proxy Statement, filed with the SEC on April 21, 2017. The complaint also alleged claims for breach of fiduciary duty, unjust enrichment, and waste of corporate assets. On May 1, 2018, the parties filed a joint stipulation and proposed order agreeing to stay the action until, inter alia , the entry of an order granting or denying any motion to dismiss the Emerson Action. On May 9, 2018, the court entered the joint stipulation agreeing to stay the action. On August 10, 2018, the parties, along with the plaintiff from the Howard action, detailed below, filed a joint stipulation and proposed order agreeing to, inter alia , consolidate the Kahr and Howard actions into an action captioned In re Genocea Biosciences, Inc. Derivative Litigation , U.S. District Court (Del.), Civil Action No. 18-cv-00186-MN (the “Genocea Consolidated Derivative Action”). The joint stipulation also proposed to stay the consolidated action pursuant to the same terms as the stay order entered in Kahr , and allow the Rosen Law Firm, P.A. and Gainey McKenna & Egleston to serve as co-lead counsel for plaintiffs in the consolidated action. On August 24, 2018, the court entered the joint stipulation agreeing to consolidate the Kahr and Howard actions, and stay the Genocea Consolidated Derivative Action. On February 4, 2019, the parties filed a joint stipulation and proposed order agreeing to extend the stay order until, inter alia , the resolution of the First Circuit appeal in the Emerson Action. On February 5, 2019, the court entered the joint stipulation agreeing to extend the stay. However, following the dismissal of the Emerson action, the plaintiff from the Kahr action, along with the plaintiff from the Howard action, detailed below, voluntarily dismissed the Genocea Consolidated Derivative Action on July 1, 2019. The court closed the Kahr action on July 1, 2019. Howard v. William Clark et al. , U.S. District Court (Del.), Civil Action No. 18-cv-00912-MN. On June 20, 2018, Julie Howard, a purported Genocea shareholder, filed a putative shareholder derivative complaint against certain of the Company’s officers and directors (including one former officer), naming the Company as the nominal defendant. The complaint alleged violations of the Securities Exchange Act of 1934, as amended, and Rule 14a-9 in connection with disclosures made in the Company’s Schedule 14A Proxy Statement, filed with the SEC on April 21, 2017. The complaint also alleged claims for breach of fiduciary duty, unjust enrichment, and waste of corporate assets. As detailed above, the Howard action was consolidated with the Kahr action into the Genocea Consolidated Derivative Action, which the court stayed until, inter alia , the resolution of the First Circuit appeal in the Emerson Action. Following the dismissal of the Emerson action, however, the plaintiff from the Kahr action voluntarily dismissed the Genocea Consolidated Derivative Action on July 1, 2019. The court closed the Howard action on July 1, 2019.

Net loss per share attributable

Net loss per share attributable to common stockholders	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Net loss per share	Net loss per share The Company computes basic and diluted loss per share using a methodology that gives effect to the impact of outstanding participating securities (the “two-class method”). For both the three and six -month periods ended June 30, 2019 and 2018 , respectively, 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, 2019 2018 Stock options 1,285 713 Warrants 4,600 3,668 ESPP 265 — Total 6,150 4,381

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting of normal recurring accruals necessary for a fair presentation of the Company’s financial statements for interim periods in accordance with accounting principles generally accepted in the United States (U.S. GAAP). We operate as one operating segment, which is discovering, researching and developing novel cancer immunotherapies. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with our audited consolidated financial statements and the accompanying notes included in our Annual Report on Form 10-K for the year ended December 31, 2018 (“2018 Form 10-K”). Our accounting policies are described in the “Notes to Consolidated Financial Statements” in our 2018 Form 10-K and updated, as necessary, in our Quarterly Reports on Form 10-Q. The December 31, 2018 condensed consolidated balance sheet data presented for comparative purposes was derived from our audited financial statements, but does not include all disclosures required by U.S. GAAP. The results of operations for the three and six months ended June 30, 2019 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period.
Use of estimates	The preparation of financial statements in conformity with U.S. 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 clinical trial accruals, estimates related to prepaid and accrued research and development expenses, stock-based compensation expense, and warrants to purchase redeemable securities. 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.
Fair value of financial instruments	The Company has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. • Level 1 - Fair values are determined by utilizing quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access; • Level 2 - Fair values are determined by utilizing quoted prices for similar assets and liabilities in active markets or other market observable inputs such as interest rates, yield curves and foreign currency spot rates; and • Level 3 - Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. The Company's financial assets consist of cash equivalents and the Company's financial liabilities consist of warrant liability.
Recently adopted accounting standards and Recently issued accounting standards	Recently adopted accounting standards Standard Description Effect on the financial statements ASU No. 2016-02, Leases (Topic 842) In February 2016, the FASB established ASC Topic 842, Leases , (ASC 842) by issuing ASU No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use model ("ROU") that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases are classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The Company adopted ASC 842 effective January 1, 2019. The adoption of ASC 842 resulted in the Company recognizing ROU assets and related operating lease liabilities of $1.7 million and $1.8 million, respectively, in our condensed consolidated balance sheet as of January 1, 2019. The Company used the modified retrospective method of adoption, with January 1, 2019 as the effective date of initial application. The Company elected the short-term lease recognition exemption for all leases that qualify. The Company elected the package of practical expedients for leases that commenced prior to January 1, 2019, allowing it not to reassess (i) whether any expired or existing contracts contain leases, (ii) the lease classification for any expired or existing leases and (iii) the initial indirect costs for any existing leases. ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. The new standard largely aligns the accounting for share-based payment awards issued to employees and nonemployees by expanding the scope of ASC 718 to apply to nonemployee share-based transactions, as long as the transaction is not effectively a form of financing. The Company adopted ASU No. 2018-07 effective January 1, 2019. The adoption of ASU No. 2018-07 did not have a material impact on the Company's condensed consolidated financial statements. Recently issued accounting standards Standard Description Effect on the financial statements ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables and available-for-sale debt securities. The new guidance will be effective for the Company beginning in the first quarter of 2020, with early adoption permitted. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements. ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement which requires public entities to disclose certain new information and modifies some disclosure requirements. The new guidance will be effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements. ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. In August 2018, the FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and recognize as an asset. The new guidance will be effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2019. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements.

Fair value of financial instr_2

Fair value of financial instruments (Tables)	6 Months Ended
	Jun. 30, 2019
Cash and Cash Equivalents [Abstract]
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]	As of June 30, 2019 , the Company had the following potentially issuable shares of common stock related to unexercised warrants outstanding: Shares Exercise price Expiration date Classification First Warrant 9,216 $ 65.92 Q4 2019 Equity Second Warrant 41,177 $ 6.80 Q2 2023 Equity 2018 Public Offering Warrants 3,616,944 $ 9.60 Q1 2023 Liability Private Placement Warrants 932,812 $ 4.52 Q1 2024 Equity Pre-Funded Warrants 531,250 $ 0.08 Q1 2039 Equity 5,131,399
Schedule of financial instruments measured at fair value on recurring basis	Quoted prices in active markets Significant other observable inputs Significant unobservable inputs Total (Level 1) (Level 2) (Level 3) June 30, 2019 Assets: Cash equivalents $ 19,802 $ 19,802 $ — $ — Total assets $ 19,802 $ 19,802 $ — $ — Liabilities: Warrant liability $ 5,389 $ — $ — $ 5,389 Total liabilities $ 5,389 $ — $ — $ 5,389 December 31, 2018 Assets: Cash equivalents $ 24,651 $ 24,651 $ — $ — Total assets $ 24,651 $ 24,651 $ — $ — Liabilities: Warrant liability $ 3,472 $ — $ — $ 3,472 Total liabilities $ 3,472 $ — $ — $ 3,472
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]	The following table details the assumptions used in the Monte Carlo simulation models used to estimate the fair value of the Warrant Liability as of June 30, 2019 and December 31, 2018 , respectively: June 30, 2019 December 31, 2018 Stock price $ 3.92 $ 2.32 Volatility 121.5 % 111.3 % Remaining term (years) 3.6 4.1 Expected dividend yield — — Risk-free rate 1.7 % 2.4%-2.5% Range of annual acquisition event probability 15.0%-30.0% 0.0%-30.0%
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation	The following table reflects the change in the Company’s Level 3 warrant liability from December 31, 2018 through June 30, 2019 : Warrant Liability Balance at December 31, 2018 $ 3,472 Change in fair value 1,917 Balance at June 30, 2019 $ 5,389

Accrued expenses and other cu_2

Accrued expenses and other current liabilities (Tables)	6 Months Ended
	Jun. 30, 2019
Payables and Accruals [Abstract]
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): June 30, December 31, 2019 2018 Research and development $ 1,462 $ 759 Payroll and employee-related 1,491 2,147 Other current liabilities 2,097 910 Total $ 5,050 $ 3,816

Long-term debt (Tables)

Long-term debt (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Schedule of future principal payments	Future principal payments, including the End of Term Charges, are as follows (in thousands): June 30, 2019 2019 $ 542 2020 7,399 2021 6,462 Total $ 14,403 The Company's balance sheet classification has been updated to reflect the extension of interest only payments.

Warrants (Tables)

Warrants (Tables)	6 Months Ended
	Jun. 30, 2019
Class of Stock [Line Items]
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]	As of June 30, 2019 , the Company had the following potentially issuable shares of common stock related to unexercised warrants outstanding: Shares Exercise price Expiration date Classification First Warrant 9,216 $ 65.92 Q4 2019 Equity Second Warrant 41,177 $ 6.80 Q2 2023 Equity 2018 Public Offering Warrants 3,616,944 $ 9.60 Q1 2023 Liability Private Placement Warrants 932,812 $ 4.52 Q1 2024 Equity Pre-Funded Warrants 531,250 $ 0.08 Q1 2039 Equity 5,131,399
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]	The following table details the assumptions used in the Monte Carlo simulation models used to estimate the fair value of the Warrant Liability as of June 30, 2019 and December 31, 2018 , respectively: June 30, 2019 December 31, 2018 Stock price $ 3.92 $ 2.32 Volatility 121.5 % 111.3 % Remaining term (years) 3.6 4.1 Expected dividend yield — — Risk-free rate 1.7 % 2.4%-2.5% Range of annual acquisition event probability 15.0%-30.0% 0.0%-30.0%

Stock and employee benefit pl_2

Stock and employee benefit plans (Tables)	6 Months Ended
	Jun. 30, 2019
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 and restricted stock awards granted to employees and non-employees and has been reported in the Company’s condensed consolidated statements of operations as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development $ 170 $ 159 $ 352 $ 300 General and administrative 304 433 551 936 Total $ 474 $ 592 $ 903 $ 1,236
Schedule of stock option activity for employees and nonemployees	The following table summarizes stock option activity for employees and non-employees (shares in thousands): Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2018 893 $ 18.79 $ — Granted 501 $ 4.66 Exercised (5 ) $ 4.32 Cancelled (104 ) $ 25.24 Outstanding at June 30, 2019 1,285 $ 12.81 8.32 $ 1,435 Exercisable at June 30, 2019 402 $ 25.57 6.38 $ —

Commitments and contingencies (

Commitments and contingencies (Tables)	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments	are as follows (in thousands): June 30, 2019 2019 $ 821 2020 1,477 2021 1,474 2022 1,510 2023 and thereafter 3,401 Total lease payments 8,683 Less imputed interest (1,777 ) Total $ 6,906

Net loss per share attributab_2

Net loss per share attributable to common stockholders (Tables)	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [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, 2019 2018 Stock options 1,285 713 Warrants 4,600 3,668 ESPP 265 — Total 6,150 4,381

Organization and operations (De

Organization and operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 58,670		$ 58,670		$ 26,361
Loss from operations	$ 10,066	$ 9,788	19,543	$ 20,172
Net cash used in operating activities			$ 17,942	$ 23,375

Summary of significant accoun_3

Summary of significant accounting policies - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents	$ 58,670	$ 26,361
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted Cash and Cash Equivalents			$ 300
Cash and cash equivalents			$ (300)

Fair value of financial instr_3

Fair value of financial instruments - Schedule of cash equivalents and investments carried at fair value (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jan. 01, 2018
Fair Value, Measurements, Recurring
Assets:
Total assets	$ 19,802	$ 24,651
Liabilities:
Total liabilities	5,389	3,472
Fair Value, Measurements, Recurring | (Level 1)
Assets:
Total assets	19,802	24,651
Liabilities:
Warrant liability	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | (Level 2)
Assets:
Total assets	0	0
Liabilities:
Warrant liability	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | (Level 3)
Assets:
Total assets	0	0
Liabilities:
Warrant liability	5,389	3,472
Total liabilities	5,389	3,472
Money market funds | Fair Value, Measurements, Recurring
Assets:
Included in cash equivalents	19,802	24,651
Money market funds | Fair Value, Measurements, Recurring | (Level 1)
Assets:
Included in cash equivalents	19,802	24,651
Money market funds | Fair Value, Measurements, Recurring | (Level 2)
Assets:
Included in cash equivalents	0	0
Money market funds | Fair Value, Measurements, Recurring | (Level 3)
Assets:
Included in cash equivalents	0	0
Warrants | (Level 3)
Liabilities:
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	$ 5,389	$ 3,472	$ 18,200

Fair value of financial instr_4

Fair value of financial instruments - Assumptions used in the Monte Carlo simulation models (Details)	Jun. 30, 2019$ / shares	Dec. 31, 2018$ / shares	Jan. 01, 2018
Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input			0.024
Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input			0.025
Measurement Input, Share Price | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	3.92	2,320
Measurement Input, Price Volatility | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	1.215	1.113
Measurement Input, Expected Term | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Term	3 years 6 months 20 days	4 years 1 month 7 days
Measurement Input, Expected Dividend Rate | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0	0
Measurement Input, Risk Free Interest Rate | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.017
Measurement Input, Risk Free Interest Rate | Minimum [Member] | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.024
Measurement Input, Risk Free Interest Rate | Maximum [Member] | Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.025
Measurement Input, Acquisition Event Probability [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.150		0
Measurement Input, Acquisition Event Probability [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.300		0.300

Fair value of financial instr_5

Fair value of financial instruments - Change in the Company’s Level 3 Warrant liabilities (Details) - Warrants - (Level 3) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Issuance of Warrants	$ 3,472
Change in fair value	1,917
Balance at June 30, 2019	$ 5,389

Accrued expenses and other cu_3

Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Research and development	$ 1,462	$ 759
Payroll and employee-related	1,491	2,147
Other current liabilities	2,097	910
Total	$ 5,050	$ 3,816

Long-term debt - Narrative (Det

Long-term debt - Narrative (Details) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Apr. 24, 2018
Long-Term Debt
Issuance of common stock	$ 38,167,000	$ 14,026,000	$ 2,922,000	$ 35,864,000
Common Stock
Long-Term Debt
Shares	5,131,399				5,131,399
Line of Credit | 2018 Term Loan
Long-Term Debt
Debt financing								$ 14,000,000
Interest rate (as a percent)								7.75%
Line of Credit | 2018 Term Loan | Prime rate
Long-Term Debt
Variable rate (as a percent)								2.75%
Line of Credit | 2014 Term Loan
Long-Term Debt
Effective interest rate (as a percent)	11.40%				11.40%
Interest expense	$ 400,000				$ 900,000	$ 800,000
Line of Credit | 2014 Term Loan, First Tranche
Long-Term Debt
Outstanding borrowings	$ 13,700,000				$ 13,700,000		$ 14,800,000
Common Stock
Long-Term Debt
Issuance of common stock (in shares)	12,074,000	3,200,000	440,000	6,790,000
Issuance of common stock	$ 12,000	$ 3,000	$ 1,000	$ 7,000

Long-term debt - Schedule of fu

Long-term debt - Schedule of future principal payments (Details) - 2014 Term Loan - Line of Credit $ in Thousands	Jun. 30, 2019USD ($)
2019	$ 542
2020	7,399
2021	6,462
Total	$ 14,403

Stockholders' equity - Narrativ

Stockholders' equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 17, 2018	Feb. 28, 2019	Jan. 31, 2018	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019	Dec. 31, 2018	Jan. 01, 2018	May 08, 2015	Mar. 02, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized (in shares)				85,000,000				85,000,000
Par value (in dollars per share)				$ 0.001				$ 0.001
Preferred stock authorized (in shares)				25,000,000				25,000,000
Preferred stock par value (in dollars per share)				$ 0.001				$ 0.001
Common stock issued (in shares)				26,149,689				26,149,689			10,846,397
Preferred stock issued (in shares)				1,635				1,635
Additional paid in capital, preferred stock						$ 300			$ 300
Payment of financing and stock issuance Costs			$ 4,000
Payments of issuance costs			2,600
Payments for warrant issuance			$ 1,400
Proceeds from issuance of common stock								$ 52,194	$ 52,538
At-the-market equity offering program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering amount (up to)													$ 50,000	$ 40,000
Preferred Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued (in shares)											1,635
Issuance of common stock (in shares)							701,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock (in shares)				12,074,000	3,200,000	440,000	6,790,000
Common Stock | At-the-market equity offering program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock (in shares)										500,000
Proceeds from issuance of common stock										$ 4,000
Equity Rights Letter Agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of stock, price per share (in dollars per share)		$ 4.0208
Sale of stock, consideration received on transaction		$ 13,800
Equity Rights Letter Agreement | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in transaction (in shares)		3,200,000
Equity Rights Letter Agreement | Pre-Funded Warrant Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in transaction (in shares)		531,250
Equity Rights Letter Agreement | Private Placement Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in transaction (in shares)		932,812
Private Placement - Second Closing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in transaction (in shares)		6,400,000
Underwritten Public Offering | Common Stock | Concurrent Offerings
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants to purchase common stock (in shares)			3,335,313
Issuance of common stock (in shares)			6,670,625
Underwritten Public Offering | Common Stock | Over-Allotment Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants to purchase common stock (in shares)			1,000,594			299,475			299,475
Underwritten Public Offering | Common Stock | Additional Overallotment Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants to purchase common stock (in shares)			500,297
Underwritten Public Offering | Convertible Preferred Stock | Concurrent Offerings
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock par value (in dollars per share)	$ 0.001
Preferred stock issued (in shares)			1,635
Sale of stock, consideration received on transaction	$ 1,600
Warrants to purchase common stock (in shares)			102,188
Shares issued upon conversion (in shares)			204,375
Underwritten Public Offering | Common Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Par value (in dollars per share)	$ 0.001
Sale of stock, consideration received on transaction	$ 53,400
Share Price (in dollars per share)	$ 8
Shares issued upon conversion (in shares)				125				125
Ownership threshold								9.99%
Warrants | (Level 3)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of Warrants				$ 5,389				$ 5,389			$ 3,472	$ 18,200
Change in fair value								$ 1,917

Warrants (Details)

Warrants (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)$ / sharesshares	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)$ / sharesshares	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)$ / shares	Jan. 01, 2018USD ($)
First Warrants
Class of Stock [Line Items]
Shares | shares	9,216		9,216
Exercise price | $ / shares			$ 65.92
Second Warrant
Class of Stock [Line Items]
Shares | shares	41,177		41,177
Exercise price | $ / shares			$ 6.80
Public Offering Warrants
Class of Stock [Line Items]
Shares | shares	3,616,944		3,616,944
Exercise price | $ / shares			$ 9.60
Initial Closing Private Placement Warrants
Class of Stock [Line Items]
Shares | shares	932,812		932,812
Exercise price | $ / shares			$ 4.52
Initial Closing Pre-Funded Warrants
Class of Stock [Line Items]
Shares | shares	531,250		531,250
Exercise price | $ / shares			$ 0.08
Warrants To Purchase Common Stock
Class of Stock [Line Items]
Shares | shares	5,131,399		5,131,399
(Level 3) | Warrants
Class of Stock [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value | $	$ 5,389		$ 5,389		$ 3,472	$ 18,200
Change in fair value of warrants | $	3,870	$ 5,498	(1,917)	$ 199
Derivative, Loss on Derivative | $				$ 2,300
Warrant liability | $	$ 5,389		$ 5,389		$ 3,472
Measurement Input, Share Price | Warrants
Class of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input | $ / shares	3.92		3.92		2,320
Measurement Input, Price Volatility | Warrants
Class of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input	1.215		1.215		1.113
Measurement Input, Expected Term | Warrants
Class of Stock [Line Items]
Warrants and Rights Outstanding, Term	3 years 6 months 20 days		3 years 6 months 20 days		4 years 1 month 7 days
Measurement Input, Expected Dividend Rate | Warrants
Class of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input	0		0		0
Measurement Input, Risk Free Interest Rate | Warrants
Class of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.017		0.017

Stock and employee benefit pl_3

Stock and employee benefit plans - Schedule of stock-based compensation expense for stock options granted to employees and non-employees (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock Based Compensation Expense
Total	$ 474	$ 592	$ 903	$ 1,236
Research and development
Stock Based Compensation Expense
Total	170	159		300
General and administrative
Stock Based Compensation Expense
Total	$ 304	$ 433		$ 936

Stock and employee benefit pl_4

Stock and employee benefit plans - Schedule of stock option activity for employees and nonemployees (Details) - Stock options $ / shares in Units, shares in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Shares
Outstanding at the beginning of the period (in shares) | shares	893
Granted (in shares) | shares	501
Exercised (in shares) | shares	(5)
Canceled (in shares) | shares	(104)
Outstanding at the end of the period (in shares) | shares	1,285	893
Exercisable at the end of the period (in shares) | shares	402
Weighted- Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 18.79
Granted (in dollars per share) | $ / shares	4.66
Exercised (in dollars per share) | $ / shares	4.32
Canceled (in dollars per share) | $ / shares	25.24
Outstanding at the end of the period (in dollars per share) | $ / shares	12.81	$ 18.79
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 25.57
Weighted- Average Remaining Contractual Term (years)
Outstanding at the beginning/end of the period	8 years 3 months 27 days
Exercisable at the end of the period	6 years 4 months 17 days
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars) | $	$ 1,435	$ 0
Exercisable at the end of the period (in dollars) | $	$ 0

Stock and employee benefit pl_5

Stock and employee benefit plans - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Feb. 10, 2014
Stock option activity for employees and nonemployees
Total	$ 474	$ 592	$ 903	$ 1,236
Performance-based stock options
Stock option activity for employees and nonemployees
Options outstanding (in shares)	7,042		7,042
ESPP | 2014 ESPP
Stock option activity for employees and nonemployees
Number of shares of common stock authorized under the plan					337,597

Commitments and contingencies -

Commitments and contingencies - Schedule of future minimum lease payments (Details) $ in Thousands	Jun. 30, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 821
2020	1,477
2021	1,474
2022	1,510
2023 and thereafter	3,401
Total	8,683
Less imputed interest	(1,777)
Total	$ 6,906

Commitments and contingencies_2

Commitments and contingencies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Commitments and contingencies
Incremental borrowing rate used to calculate right of use assets			8.25%
Incremental borrowing rate used to calculated lease liability and right of use assets			10.00%
Rent expense	$ 0.3	$ 0.4	$ 0.7	$ 0.8
Master Facilities Lease 2012
Commitments and contingencies
Outstanding letter of credit	$ 0.3		$ 0.3		$ 0.3

Net loss per share attributab_3

Net loss per share attributable to common stockholders (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	6,150	4,381
Stock options
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	1,285	713
Warrants
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	4,600	3,668
ESPP
Common stock equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect
Common stock equivalents (in shares)	265	0