Immune Design 10-K 7 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Mar. 01, 2017	Jun. 30, 2016
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	IMDZ
Entity Registrant Name	Immune Design Corp.
Entity Central Index Key	1,437,786
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		25,439,857
Entity Public Float			$ 99.1

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 45,214	$ 112,921
Short-term investments	62,041	0
Accounts receivable	517	972
Inventory	607	13
Prepaid expenses	2,546	1,654
Other receivables	3,156	0
Total current assets	114,081	115,560
Property and equipment, net	414	585
Total assets	114,495	116,145
Current liabilities:
Accounts payable	4,559	3,074
Accrued liabilities	4,935	3,959
Accrued litigation-related settlement	7,250	0
Deferred revenue and other current liabilities	2,519	78
Total current liabilities	19,263	7,111
Other noncurrent liabilities	56	41
Commitments and contingencies (Note 9)
Stockholders’ equity:
Common stock, $0.001 par value per share; 100,000,000 authorized at December 31, 2016 and 2015; 25,413,055 and 20,153,202 shares issued and outstanding at December 31, 2016 and 2015, respectively	25	20
Preferred stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2016 and 2015; no shares issued or outstanding	0	0
Additional paid-in capital	278,913	239,181
Accumulated deficit	(183,738)	(130,208)
Accumulated other comprehensive loss	(24)	0
Total stockholders’ equity	95,176	108,993
Total liabilities and stockholders’ equity	$ 114,495	$ 116,145

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Common stock
Par value per share (in USD per share)	$ 0.001	$ 0.001
Shares issued (in shares)	25,413,055	20,153,202
Shares outstanding (in shares)	25,413,055	20,153,202
Shares authorized (in shares)	100,000,000	100,000,000
Preferred stock
Par value per share (in USD per share)	$ 0.001	$ 0.001
Shares issued (in shares)	0	0
Shares outstanding (in shares)	0	0
Shares authorized (in shares)	10,000,000	10,000,000

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Licensing revenue	$ 7,000	$ 3,500	$ 4,500
Product sales	1,627	1,853	881
Collaborative revenue	4,633	4,157	1,052
Total revenues	13,260	9,510	6,433
Operating expenses:
Cost of product sales	481	774	638
Research and development	45,134	33,087	22,746
General and administrative	21,859	15,134	12,927
Total operating expenses	67,474	48,995	36,311
Loss from operations	(54,214)	(39,485)	(29,878)
Interest and other income	684	40	4
Change in fair value of convertible preferred stock warrant liability	0	0	(4,277)
Net loss	(53,530)	(39,445)	(34,151)
Unrealized gain (loss) on investments	(24)	0	0
Comprehensive loss	$ (53,554)	$ (39,445)	$ (34,151)
Earnings Per Share
Basic and diluted net loss per share (in dollars per share)	$ (2.47)	$ (2.06)	$ (4.56)
Weighted Average Number of Shares Outstanding, Diluted
Weighted-average shares used to compute basic and diluted net loss per share (in shares)	21,638,468	19,155,918	7,494,790

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]Convertible preferred stock [Member]	Common stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance, convertible preferred shares (in shares) at Dec. 31, 2013		9,769,422
Beginning balance, preferred stock at Dec. 31, 2013		$ 81,394
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of preferred stock to common stock (in shares)		(9,769,422)	9,769,422
Conversion of preferred stock to common stock	$ 81,394	$ (81,394)	$ 10	$ 81,384
Ending balance, preferred stock at Dec. 31, 2014		0
Beginning balance (in shares) at Dec. 31, 2013			369,460
Beginning balance at Dec. 31, 2013	(55,834)		$ 3	775	$ (56,612)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon completion of IPO, net of offering costs (in shares)			5,410,564
Issuance of common stock upon completion of IPO, net of offering costs	57,807		$ 5	57,802
Conversion of preferred stock to common stock (in shares)		(9,769,422)	9,769,422
Conversion of preferred stock to common stock	81,394	$ (81,394)	$ 10	81,384
Issuance of common stock upon exercise of warrants (in shares)			1,308,863
Issuance of common stock upon exercise of warrants	8,150		$ 1	8,149
Conversion of preferred stock warrant liability	7,613			7,613
Reverse stock split true up			$ (2)	2
Exercise of stock options (in shares)			20,508
Exercise of stock options	23			23
Stock-based compensation	1,344			1,344
Net loss	(34,151)				(34,151)
Unrealized loss on investments	0
Ending balance (in shares) at Dec. 31, 2014			16,878,817
Ending balance at Dec. 31, 2014	$ 66,346	$ 0	$ 17	157,092	(90,763)	0
Ending balance, preferred stock at Dec. 31, 2015	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon completion of IPO, net of offering costs (in shares)			3,047,409
Issuance of common stock upon completion of IPO, net of offering costs	$ 75,359		$ 3	75,356
Exercise of stock options (in shares)	219,290		219,290
Exercise of stock options	$ 303			303
Issuance of common stock in connection with ESPP purchase (in shares)			7,686
Issuance of common stock in connection with ESPP purchase	133			133
Stock-based compensation	6,297			6,297
Net loss	(39,445)				(39,445)	0
Unrealized loss on investments	$ 0
Ending balance (in shares) at Dec. 31, 2015	20,153,202		20,153,202
Ending balance at Dec. 31, 2015	$ 108,993	$ 0	$ 20	239,181	(130,208)	0
Ending balance, preferred stock at Dec. 31, 2016	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon completion of IPO, net of offering costs (in shares)			5,226,369
Issuance of common stock upon completion of IPO, net of offering costs	$ 30,310		$ 5	30,305
Exercise of stock options (in shares)	20,782		20,782
Exercise of stock options	$ 65			65
Issuance of common stock in connection with ESPP purchase (in shares)			12,702
Issuance of common stock in connection with ESPP purchase	79			79
Stock-based compensation	9,283			9,283
Net loss	(53,530)				(53,530)	0
Unrealized loss on investments	$ (24)					(24)
Ending balance (in shares) at Dec. 31, 2016	25,413,055		25,413,055
Ending balance at Dec. 31, 2016	$ 95,176	$ 0	$ 25	$ 278,913	$ (183,738)	$ (24)

Consolidated Statements of Con6

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) Parenthetical - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock issuance costs	$ 2,400
Common stock [Member]
Share price (in USD per share)		$ 6.25	$ 26.5	$ 12
Stock issuance costs		$ 2,355	$ 5,397	$ 7,100
Warrant exercise price (in USD per share)				$ 12

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (53,530)	$ (39,445)	$ (34,151)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	304	243	238
Amortization of premium/discount on investments	126	0	0
Stock-based compensation expense	9,283	6,297	1,344
Revaluation of convertible preferred stock warrant liability	0	0	4,277
Changes in operating assets and liabilities:
Accounts receivable	455	998	(1,883)
Inventory	(594)	12	(8)
Prepaid expenses	(892)	(1,021)	(454)
Other receivables	(3,059)	0	0
Accounts payable	1,485	(3,829)	6,037
Accrued liabilities	976	(519)	3,424
Accrued litigation-related settlement	7,250	0	0
Deferred revenue and other liabilities	2,456	(537)	507
Net cash used in operating activities	(35,740)	(37,801)	(20,669)
Investing activities
Purchases of property and equipment	(133)	(427)	(344)
Purchases of short-term investments	(102,288)	0	0
Maturities of short-term investments	40,000	0	0
Net cash used in investing activities	(62,421)	(427)	(344)
Financing activities
Issuance of common stock in public offering, net of offering costs	30,310	75,359	57,807
Proceeds from exercise of preferred stock warrants	0	0	8,150
Proceeds from exercise of stock options and employee stock purchases	144	436	23
Net cash provided by financing activities	30,454	75,795	65,980
Net (decrease) increase in cash and cash equivalents	(67,707)	37,567	44,967
Cash and cash equivalents, beginning of period	112,921	75,354	30,387
Cash and cash equivalents, end of period	$ 45,214	$ 112,921	$ 75,354

Description of the Business

Description of the Business	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business Immune Design Corp. (we, us or our) is a clinical-stage immunotherapy company focused on cancer with next-generation in vivo approaches designed to enable the body’s immune system to fight disease. We have engineered our technologies to activate the immune system’s natural ability to create tumor-specific cytotoxic T cells (CTLs) to fight cancer. We are developing multiple product candidates from our two discovery platforms, ZVex ® and GLAAS ® . Our primary product candidates, CMB305 and G100, utilize multiple immuno-oncology approaches and are in multiple Phase 1and Phase 2 trials. In addition, we have licensed the right to use the GLAAS platform in specific infectious disease and allergy indications. We were incorporated in February 2008 in the State of Delaware. Our operations are headquartered in Seattle, Washington and we have an additional facility in South San Francisco, California.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Use of Estimates The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP). To conform with GAAP, the preparation of our financial statements requires management to make judgments, assumptions, and estimates that affect the amounts reported in our financial statements and accompanying notes. Estimates are used for, but not limited to, accruals for clinical trial activity, other accrued liabilities, and assumptions used in determining stock-based compensation expenses and convertible preferred stock warrant liability. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable. Actual results could differ materially from those estimates. Principles of Consolidation Our consolidated financial statements include the financial position and results of operations of Immune Design Corp. and Immune Design Ltd., our wholly owned subsidiary. Immune Design Ltd. was incorporated in the United Kingdom in February 2016 and to date there have been no financial transactions or balances related to this entity. Segments We operate in one segment and use cash flow as the primary measure to manage our business and do not segment the business for internal reporting or decision-making purposes. Offering Costs Offering costs represent legal, accounting and other direct costs related to our efforts to raise capital through our follow-on public offerings in September 2016 and April 2015 and for our initial public offering (IPO) in July 2014. These costs were deferred until completion of the follow-on public offerings and IPO, respectively, at which time they were reclassified to additional paid-in capital as a reduction of the proceeds. Cash and Cash Equivalents Cash equivalents are highly liquid investments with a maturity of 90 days or less at the date of purchase and primarily consist of investments in money market funds. In addition, we maintain cash balances with financial institutions in excess of insured limits and do not anticipate any losses on such cash balances. Concentration of Risk We limit our credit risk associated with cash and cash equivalents by placing our deposits with banks we believe are highly creditworthy and our investments with highly rated money market funds. Short-Term Investments Our short-term investments include funds invested in U.S. Treasury securities with a final maturity of each security of less than one year. All investments are classified as available-for-sale securities and are recorded at fair value based on quoted prices in active markets, with unrealized gains and losses excluded from earnings and reported in other comprehensive income (loss). Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Realized gains and losses and declines in fair value that are deemed to be other than temporary are reflected in the condensed consolidated statements of operations and comprehensive income (loss) using the specific-identification method. Accounts Receivable Accounts receivable are amounts due from other companies related primarily to licensing fees, product sales and research and development services. We considered the need for an allowance for doubtful accounts and have concluded that no allowance was needed as of December 31, 2016 or 2015 , as the estimated risk of loss on our accounts receivable was determined to be minimal. Inventory Inventory is recorded at the lower of cost or market. Cost includes amounts related to materials and labor, and is determined on a specific identification basis in a manner which approximates the first-in, first-out method. We record adjustments to inventory for potentially excess, obsolete, expired, or impaired items. Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over an estimated useful life that is generally three years , while leasehold improvements are amortized over the shorter of their estimated useful lives or the related lease term. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is credited or charged to operations. Maintenance and repairs are expensed as incurred. Asset improvements are capitalized. Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets might not be recoverable. Conditions that would necessitate an impairment assessment include a significant decline in the observable market value of an asset, a significant change in the extent or manner in which an asset is used, or any other significant adverse change that would indicate that the carrying amount of an asset is not recoverable. Accrued Liabilities Accrued liabilities represent accrued compensation including vacation accruals, unearned revenue and accrued expenses. As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued professional services and research and development expenses. This process involves reviewing contracts and vendor agreements, communicating with our applicable personnel to identify services that have been performed on our behalf. We estimate the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual cost. We make estimates of our accrued expenses as of each balance sheet date in our consolidated financial statements based on facts and circumstances known to us. We base our expenses related to contract manufacturing and clinical trials on our estimates of the services received and efforts expended pursuant to contracts with multiple contract manufacturing organizations and clinical research organizations that conduct and manage supply and clinical trials on our behalf. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period. To date, we have not experienced any significant adjustments to our estimates. Leases and Deferred Rent We have entered into lease agreements for laboratory and office facilities. These leases are classified as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facilities leases, including allowances to fund leasehold improvements and rent escalations are accrued as deferred rent. Leasehold improvements funded by the lessor are capitalized and are recognized as reductions to rental expense on a straight-line basis over the term of the lease. Series C Convertible Preferred Stock Warrant Liability We account for our warrants in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 480-10, Distinguishing Liabilities from Equity , which requires that a financial instrument, other than an outstanding share, that, at inception, includes an obligation to repurchase the issuer’s equity shares regardless of the timing or likelihood of the redemption, shall be classified as a liability. We measure the fair value of the warrant liability based on the fair value of the warrants which we determine based on an allocation of our enterprise value to all classes of equity and preferred stock, including the warrants. In valuing the warrants, we utilized the income method approach in combination with a Monte Carlo simulation, which is a method that evaluates many possible value outcomes to establish the expected value of an asset. This methodology allows the modeling of securities with complex terms, such as the warrants, where path dependency, floors, caps, triggers, changes of control and down round financing provisions can be taken into account. In each reporting period, we record any change in fair value of the warrants as a non-operating gain or loss in the consolidated statements of operations. See Note 12 for additional information. Revenue Recognition We derive our revenue from collaboration and licensing agreements and the sale of products associated with material transfer, collaboration and supply agreements. Licensing fees, are recognized when the amounts are earned and determinable during the applicable period. We recognize up-front nonrefundable license fees when due under contractual agreements and when we do not have a continuing obligation to provide services related to the agreement. Revenue associated with nonrefundable up-front license fees under arrangements where the license fees and research and development activities cannot be accounted for as separate units of accounting is deferred and recognized as revenue on a straight-line basis over the expected term of our continued involvement in the research and development process. Revenues from the achievement of research and development milestones, if deemed substantive, are recognized as revenue when the milestones are achieved, and the milestone payments are due and collectible. If not deemed substantive, we recognize such milestones as revenue on a straight-line basis over the remaining expected term of continued involvement in the research and development process. Milestones are considered substantive if all of the following conditions are met: (1) the milestone is nonrefundable, (2) achievement of the milestone was not reasonably assured at the inception of the arrangement, (3) substantive effort is involved to achieve the milestone and (4) the amount of the milestone appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone and any ongoing research and development or other services are priced at fair value. Payments received in advance of work performed are recorded as unearned revenue. Certain agreements from which we derive our revenue include multiple deliverables. We recognize the revenue for each deliverable at fair value determined to be the estimated selling price in cases when neither vendor specific objective evidence nor third-party evidence is available. Revenue is recognized when all of the following criteria are met: (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the price to the customer is fixed or determinable and (4) collectability is reasonably assured. The evaluation of these revenue recognition criteria requires significant management judgment. For instance, we use judgment to assess collectability based on factors such as the customer’s creditworthiness and past collection history, if applicable. If we determine that collection of a payment is not reasonably assured, revenue recognition is deferred until receipt of payment. We also use judgment to assess whether a price is fixed or determinable including, but not limited to, reviewing contractual terms and conditions related to payment terms. Revenue from product sales of glucopyranosyl lipid A (GLA), a product from our GLAAS platforms, is recognized when the risk of loss has passed to the customer or deferred until such time that risk of loss has passed. All revenues associated from the sale of GLA products supplied by us are reported under product sales with the applicable costs reported under cost of product sales. Product sales consist of the direct costs associated with the manufacture and formulation of GLA, including costs to purchase raw materials, third-party contract manufacturing costs, assay testing and ongoing product stability testing. We consider significant revenue concentrations to be customers who account for 10% or more of total revenues generated by us during the periods presented. We had collaboration partners that accounted for: 64% , 35% and 1% of revenue for the year ended December 31, 2016 ; 44% , 36% and 20% of revenue for the year ended December 31, 2015 ; and 55% , 28% and 16% of revenue for the year ended December 31, 2014 . The collaboration partners owed a total of 100% and 98% of accounts receivable as of December 31, 2016 and 2015 , respectively. We do not believe the loss of such customers would have a material adverse effect on us. Stock-Based Compensation We account for stock-based compensation under the fair value method. Stock-based compensation costs related to employees and directors is measured at the grant date, based on the fair-value-based measurement of the award estimated using the Black-Scholes option-pricing model, and is recognized as expense over the requisite service period on a straight-line basis. Options granted to non-employee service providers are accounted for at estimated fair value using the Black-Scholes option-pricing model and are remeasured over the vesting term as earned. We recognize compensation expense for only the portion of options expected to vest. Therefore, management applied an estimated forfeiture rate that was derived from historical employee termination behavior. If the actual number of forfeitures differs from these estimates, adjustments to compensation expense may be required in future periods. Research and Development Research and development costs are expensed as incurred. Research and development costs primarily include personnel costs, materials and manufacturing to support clinical trials, fees paid to consultants and outside service providers, costs to conduct clinical trials and allocated overhead. Amounts incurred in connection with collaboration agreements are also included in research and development expense. Payments made prior to the receipt of goods or services to be used in research and development are deferred until the goods or services are received. Income Taxes Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and the operating loss and tax credit carry forwards. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets and liabilities are measured at the balance sheet date using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period such tax rate changes are enacted. Our net deferred tax asset has been fully offset by a valuation allowance because of our history of losses. Any potential accrued interest and penalties related to unrecognized tax benefits within operations would be recorded as income tax expense. To date, there have been no interest or penalties charged to us related to the underpayment of income taxes. Comprehensive Loss Comprehensive loss is composed of net loss and other comprehensive income or loss that are excluded from net loss. For the year ended December 31, 2016, other comprehensive loss consists of unrealized losses on our available-for-sale securities. For the years ended December 31, 2015 and 2014, there was no difference between comprehensive loss and net loss. Subsequent Events We consider events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. Recent Accounting Pronouncements In May 2014, FASB issued an Accounting Standards Update (ASU) amending revenue recognition guidance and requiring more detailed disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. In August 2015, the FASB deferred the effective date of the revenue recognition guidance to reporting periods beginning after December 15, 2017. The new standard permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). We currently anticipate adopting the new standard effective January 1, 2018, using the modified retrospective method. We will continue to monitor additional modifications, clarifications or interpretations undertaken by the FASB that may impact our current conclusions. While we are still in the process of completing our impact assessment, we do not currently anticipate a material impact on our financial position and results of operations. In February 2016, FASB issued ASU 2016-02 related to lease accounting. This standard will require organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases that are greater than 12 months in duration. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from previous GAAP. There continues to be a differentiation between finance leases and operating leases, however, the principal difference from previous guidance is that the lease assets and lease liabilities arising from operating leases will be recognized on the balance sheets. For capital or finance leases, lessees will recognize amortization of the right-of-use asset separately from interest on the lease liability. For operating leases, lessees will recognize a single total lease expense. The standard is effective for public companies for the fiscal years and interim reporting periods beginning after December 15, 2018. We are evaluating the guidance to determine the potential impact on our results of operations, financial condition, cash flows, and financial statement disclosures. In March 2016, the FASB issued ASU No. 2016-09 that relates to share-based payments. The amendments in this update simplify several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, statutory tax withholding requirements, as well as classification within the statement of cash flows. The guidance will be effective for the annual periods beginning after December 15, 2016, and interim periods within those annual periods. The Company is currently evaluating the impact of the new pronouncement on its financial statements . In August 2016, the FASB issued ASU No. 2016-15 which provides new guidance on the classification of certain cash receipts and payments in the statement of cash flows. The new guidance is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The Company will be required to adopt the new guidance beginning with its first fiscal quarter of 2018; early adoption is permitted. The Company is currently assessing the impact that the new guidance will have on its consolidated statements of cash flows. In November 2016, the FASB issued ASU No. 2016-18 that relates to restricted cash. The new guidance requires amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The Company will be required to revise its consolidated statements of cash flows to adopt the new guidance beginning with its first fiscal quarter of 2018; early adoption is permitted. Adoption of the new guidance will not impact the Company's financial position and results of operations.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Because of net losses recognized in each period, potential common shares issuable upon the exercise of outstanding stock options and warrants and the conversion of preferred shares in the IPO into common shares have not been reflected in the calculation of diluted net loss per share due to the anti-dilutive effect. Diluted net loss per share, therefore, does not differ from basic net loss per share. The common stock equivalents issuable upon the conversion or exercise of the following dilutive securities has been excluded from the computation of diluted net loss per share attributable to common stockholders calculation because their effect would have been anti-dilutive for the periods presented: DECEMBER 31, 2016 2015 2014 Outstanding options to purchase common stock 3,590,393 2,832,467 1,907,091 Unvested restricted stock units 107,250 — — 3,697,643 2,832,467 1,907,091

Cash Equivalents and Short-Term

Cash Equivalents and Short-Term Investments (Notes)	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Cash Equivalents and Short-Term Investments	Cash Equivalents and Short-Term Investments The amortized cost and fair value of our cash equivalents and short-term investments at December 31, 2016 are as follows (in thousands): December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 36,412 $ 2 $ — $ 36,414 U.S. Treasury securities 62,066 2 (28 ) 62,040 Total $ 98,478 $ 4 $ (28 ) $ 98,454 Classified as: Cash equivalents $ 36,414 Short-term investments 62,040 Total $ 98,454 All U.S. Treasury securities held as of December 31, 2016 were classified as available-for-sale securities and had contractual maturities of less than one year. There were no realized gains or losses on these securities for the period presented.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments We measure and record cash and cash equivalents and convertible preferred stock warrant liabilities at fair value in the accompanying financial statements. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value, is as follows: Level 1 : Quoted prices in active markets for identical assets or liabilities. Level 2 : Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 : Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 1 securities consist of highly liquid money market funds. The fair value of Level 1 assets has been determined using quoted prices in active markets for identical assets. In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. Prior to the closing of our IPO in 2014, our preferred stock warrant liability was classified within Level 3 and was measured at its estimated fair value on a recurring basis using the income method approach in combination with a Monte Carlo simulation. Inputs used to determine estimated fair value included the estimated fair value of the underlying stock at the valuation measurement date, the multiple scenarios outlining probabilities and the remaining contractual term of the warrants, risk-free interest rates, expected dividends, and the expected volatility of the price of the underlying stock. In July 2014, immediately prior to the closing of the IPO, all of our convertible preferred stock warrants were exercised, and the convertible preferred stock warrant liability was reclassified to stockholders’ equity (deficit). As of the exercise date, we used our IPO price to estimate the fair value of the warrants. See Note 9 for additional discussion of the warrant exercise. The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis (in thousands): December 31, 2016 LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds $ 36,414 $ — $ — $ 36,414 U.S. Treasury securities 62,040 — — 62,040 Total $ 98,454 $ — $ — $ 98,454 December 31, 2015 LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds $ 110,657 $ — $ — $ 110,657 The following table shows the reconciliation of the convertible preferred stock warrant liability measured and recorded at fair value on a recurring basis, using significant unobservable inputs (Level 3) (in thousands): ESTIMATED FAIR VALUE Balance as of December 31, 2013 3,336 Change in fair value of convertible preferred stock warrant liability 4,277 Conversion of preferred stock warrant liability into additional-paid-in-capital (7,613 ) Balance as of December 31, 2014 $ —

Inventory

Inventory	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory	Inventory Inventory consists of the following (in thousands): DECEMBER 31, 2016 2015 Raw materials $ 567 $ — Finished goods 40 13 Total inventory $ 607 $ 13

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment consists of the following (in thousands): DECEMBER 31, 2016 2015 Laboratory equipment $ 2,330 $ 2,287 Leasehold improvements 156 129 Computer equipment and software 483 448 Office equipment, furniture, and fixtures 174 160 Total 3,143 3,024 Less: accumulated depreciation and amortization (2,729 ) (2,439 ) Total property and equipment, net $ 414 $ 585 Depreciation and amortization expense was $304,000 , $243,000 and $238,000 for the years ended December 31, 2016 , 2015 and 2014 , respectively.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consist of the following (in thousands): DECEMBER 31, 2016 2015 Research and development services $ 3,027 $ 2,043 Legal and professional services 28 378 Employee compensation 1,880 1,538 Total accrued liabilities $ 4,935 $ 3,959

Series C Convertible Preferred

Series C Convertible Preferred Stock Warrant Liability	12 Months Ended
	Dec. 31, 2016
Other Liabilities Disclosure [Abstract]
Series C Convertible Preferred Stock Warrant Liability	Series C Convertible Preferred Stock Warrant Liability In October 2013, in connection with the issuance of our Series C convertible preferred stock, we issued fully exercisable warrants for the purchase of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share. All warrants were unexercised as of December 31, 2013. The estimated fair value for the 2013 warrants as of December 31, 2013 was $3.3 million . The fair value of the 2013 warrants was determined using the income method valuation model in combination with a Monte Carlo simulation in consideration of multiple early exercise triggers associated with the 2013 warrants. In April 2014, we amended the warrants to provide for their automatic net exercise if the IPO price exceeded the exercise price, immediately prior to the closing of the IPO. In July 2014, immediately prior to the closing of the IPO, warrants representing 996,940 shares of common stock were exercised for $8.1 million in cash, and warrants representing 978,592 shares of common stock were automatically net exercised for a total of 311,923 shares of common stock. Upon exercise of the warrants, the convertible preferred stock warrant liability was reclassified to stockholders’ equity (deficit). Convertible Preferred Stock In October 2013, we issued and sold 3,951,066 shares of our Series C convertible preferred stock at a price of $8.18 per share resulting in gross proceeds of $32.3 million , pursuant to a Series C convertible preferred stock and warrant purchase agreement. In connection with the issuance and sale of Series C convertible preferred stock we issued to the purchasers warrants, or 2013 warrants, to purchase an aggregate of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share. In connection with the completion of the Company’s IPO in July 2014, all outstanding shares of convertible preferred stock converted into 9,769,422 shares of common stock and all related warrants were exercised. See Note 9 for additional discussion of the exercise of the warrants.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases We lease laboratory and office space under an operating lease in Seattle, Washington. Our previous lease commenced in February 2013 and ended December 31, 2016. The terms of the facility lease provided for rental payments on a monthly basis and on a graduated scale. We recognized rent expense on a straight-line basis over the lease period and accrued for rent expense incurred but not paid. The lease also required us to pay additional amounts for operating and maintenance expenses. Through December 31, 2016 and 2015 , we incurred $156,000 and $129,000 , respectively, in leasehold improvements related to the lease and have recorded accumulated amortization of $123,000 and $92,000 , as of December 31, 2016 and 2015 , respectively. In January 2016 , we entered into a new Lease Agreement for approximately 20,133 square feet of office and laboratory space, which includes and expands on the space we previously subleased for our headquarters. The lease commenced on January 1, 2017 and has a term of five years with an option to extend the lease term by three years . The annual base rent due under the lease is $1.1 million for the first year and will increase by 2.5% each year thereafter. Under the terms of this lease agreement, we provided a $200,000 letter of credit as a security deposit in January 2017. We also lease 9,640 square feet of office space under an operating lease in South San Francisco, California. The lease commenced in January 2015 and continues through January 2020 , with an option to extend for an additional five years . The terms of the office lease provide for rental payments on a monthly basis and on a graduated scale. We recognize rent expense on a straight-line basis over the lease period and accrue for rent expense incurred but not paid. The lease also requires us to pay additional amounts for operating and maintenance expenses beginning January 2016. In connection with the lease, we were required to provide a $121,000 letter of credit as a security deposit. As of December 31, 2016 , no funds had been drawn down on the letter of credit. As of December 31, 2016 , future minimum lease payments are as follows (in thousands): 2017 $ 1,448 2018 1,486 2019 1,525 2020 1,203 2021 1,200 Total future minimum lease payments $ 6,862 Rent expense under operating leases was approximately $713,000 , $849,000 and $576,000 , for the years ended December 31, 2016 , 2015 and 2014 , respectively. Contingencies In June 2015, we entered into a clinical supply agreement with NanoPass Technologies LTD (NanoPass) for the use of their intradermal delivery device in certain of our clinical trials. In July 2015, in connection with the execution of the agreement, we paid an upfront fee of $600,000 for access and rights to use their device. In December 2015, we initiated our Phase 2 Sarcoma trial which triggered a milestone payment of $500,000 . Both the upfront fee and milestone payments were capitalized to prepaid expenses on the accompanying balance sheet and are being amortized to research and development expense over the related milestone periods. As of December 31, 2016 , the upfront and milestone payments have been fully amortized to research and development expense. In October 2016, we entered into a letter agreement with NanoPass which amended our clinical supply agreement to expand the field of use to include all oncology immunotherapy applications and include additional milestone payments to be paid to NanoPass upon achievement of certain clinical milestones. Per the terms of the letter agreement, we paid NanoPass an additional one-time non-refundable payment of $150,000 . In addition, we agreed to pay certain future milestone fees up to an aggregate of $8.8 million upon the achievement of certain clinical milestones. Under our license agreements with Infectious Disease Research Institute (IDRI), we are contingently obligated to pay any potential future milestone payments, which could total up to $2.3 million and $1.1 million , respectively, for the first and each subsequent exclusive licensed product we develop, and $1.3 million and $625,000 , respectively, for the first and each subsequent non-exclusive licensed product we develop. We are also contingently obligated to pay any potential future milestone payments to third parties as part of certain collaboration and licensing agreements, which could total up to $2.0 million in aggregate payments for the ZVex products we develop. We also have potential future royalty payments we may be required to make under our licensing agreements as described in Note 11. Payments under these agreements are uncertain due to the occurrence of the events requiring payment under these agreements, including our share of potential future milestone and royalty payments. These payments generally become due and payable only upon achievement of certain clinical development, regulatory or commercial milestones.

License and Collaboration Agree

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2016
Research and Development [Abstract]
License and Collaboration Agreements	License and Collaboration Agreements Licenses Granted In August 2014, we entered into an agreement with Sanofi under which we granted Sanofi an exclusive license for use of our GLAAS platform to discover, develop and commercialize products to treat peanut allergy. Sanofi may terminate the agreement at any time upon six months’ written notice. We recognized $7.0 million , $1.0 million and $3.5 million in milestone revenue under this agreement for the twelve months ended December 31, 2016 , 2015 and 2014 , respectively. The agreement provides for additional payments of up to $160.0 million based upon the attainment of certain development and commercialization milestones and tiered royalties on sales of approved products. We currently have two separate license agreements with MedImmune, LLC (MedImmune), entered into October 2010, pursuant to which we granted MedImmune a worldwide, sublicensable, exclusive license to use GLA to develop and sell vaccines in two different infectious disease indications. Under the license agreements, MedImmune is obligated to use commercially reasonable efforts to develop and obtain regulatory approval for a licensed product in certain markets and to market and sell licensed products in any country where it obtains regulatory approval. In 2010, MedImmune paid us upfront payments under the license agreements. Under each license agreement, MedImmune is obligated to make additional payments based on achievement of certain development, regulatory, and commercial milestones for the licensed indication. MedImmune is also obligated to pay us a low double-digit percentage share of non-royalty payments that it receives from sublicensees and a mid single-digit percentage royalty payment on net sales of licensed products, which royalty is subject to reduction under certain circumstances. Under each license agreement, MedImmune is obligated to make additional aggregate payments of $62.9 million to $72.5 million , depending on the infectious disease indication and the achievement of certain development, regulatory and commercial milestones for the licensed indication. We recognized zero , $2.5 million and $1.0 million in revenue for the achievement of development milestones under one of these license agreements for the twelve months ended December 31, 2016 , 2015 and 2014 , respectively. In May 2013, we entered into a nonexclusive license agreement granting Medicago, Inc. (Medicago) a right to research, develop, and commercialize GLA in the field of pandemic influenza. Medicago paid an upfront payment of $500,000 under the license agreement, which was recognized as revenue during the year ended December 31, 2013, and is also obligated to make additional payments of up to $9.5 million based on achievement of certain development and government contract milestones for the licensed indication. Medicago is also obligated to pay us a mid single-digit royalty on net sales of licensed products, which royalty is subject to reduction under license expiration. No revenue was recognized under the agreement for the years ended December 31, 2016 , 2015 and 2014 . Licenses Acquired In July 2008, we licensed certain patent rights, know-how and technology related to our GLAAS platform from the Infectious Disease Research Institute (IDRI), specifically products and formulations containing GLA and another synthetic TLR 4 agonist referred to as SLA. This license was amended and restated in 2010. In November 2015, we entered into a separate agreement with IDRI to license a patent related to our GLAAS technology in the field of cancer. Under this agreement, we paid IDRI an upfront license fee in the amount of $250,000 , which was recognized as research and development expense. Upon the achievement of certain developmental and regulatory milestones, we will be obligated to pay IDRI up to $250,000 and 125,000 , respectively, for the first and each subsequent licensed product we develop. In December 2015, we entered into a Second Amended and Restated License Agreement with IDRI, in which we obtained additional rights under the licensed technology, which rights vary by disease indication, and we returned to IDRI certain previously licensed GLA rights in select, primarily developing-world infectious disease indications. W e received an exclusive license for SLA products in oncology, human allergy and addiction, as well as an option to obtain additional exclusive licenses in select infectious disease indications. In December 2015, in connection with the execution of the second restated agreement, we paid an upfront fee of $2.3 million , whic h was recorded as research and development expense. We are obligated to pay IDRI up to $2.3 million and $1.1 million , respectively, in additional payments for the first and each subsequent exclusive licensed product we develop and $1.3 million and $625,000 , respectiv ely, for the first and each subsequent non-exclusive licensed product we develop based on the achievement of certain developmental and regulatory milestones. I n addition, we will be obligated to pay certain commercialization milestones and royalty payments of single-digit percentage of net sales, if and when a licensed product is commercialized. We are also obligated to share with IDRI a percentage of payments received from any third-party licensees. Additionally, if the Company exercises its option for additional infectious disease indications, it will be required to make upfront, milestone and royalty payments for such additional indications, which payments are subject to similar terms and conditions as are applicable to other milestone and royalty payments. We recognized $925,000 , $2.9 million and $500,000 in IDRI license-related milestone fees, which were expensed in research and development expenses, for the years ended December 31, 2016 , 2015 and 2014 , respectively. In 2009, we licensed certain patent rights directed to the production of dendritic cell-targeted therapeutic and prophylactic immunization strategies from the California Institute of Technology (Caltech) in exchange for shares of our common stock valued at $25,000 . We make annual minimum royalty payments of $25,000 under the license. In addition, we agreed to pay certain fees in the future, including milestone payments upon achievement of certain development and commercialization milestones and royalty payments on net sales in the low single-digit percentage, if and when commercialized, if we should elect to continue development of the related technology; however, we may terminate our development program at any time without further obligation to Caltech. In addition, we are required to pay Caltech up to an aggregate of $1.6 million in additional payments upon the achievement of certain regulatory and sales milestones. In June 2015, we entered into a clinical supply agreement with NanoPass for the use of their intradermal delivery device in certain of our clinical trials. See Note 10 for additional information. In October 2016, we entered into a license agreement with TheraVectys SA (TVS), pursuant to which we received a field limited, non-exclusive, sublicensable license for oncology uses to certain current and future intellectual property rights owned, controlled and licensed by TVS relating to lentiviral vector technologies. We will owe TVS milestone payments based on the achievement of certain development and regulatory milestones for each licensed product, in the aggregate amount of up to $5.75 million , except that the first two milestones payments are waived for CMB305/LV305. In addition, we will be obligated to pay a single commercial milestone payment for each product that achieves a specified net sales amount. We will owe royalties to TVS on product sales that are made directly by us or our affiliates, subject to certain royalty-offset provisions. For the first four products, including LV305/CMB305, royalties will be based on a low-single digit percentage of net sales, and for subsequent products, tiered royalties will be based on low-to-mid-single digit percentages of net sales. TVS will also receive a mid-single digit percentage of revenues that we receive for sublicensing the licensed intellectual property. Collaborations In October 2014, we entered into a collaboration with Sanofi Pasteur for the development of a Herpes Simplex Virus (HSV) immune therapy. Sanofi Pasteur and Immune Design are each contributing product candidates to the collaboration: Sanofi Pasteur is contributing HSV-529, a clinical-stage replication-defective HSV vaccine product candidate, and we contribute G103, our preclinical trivalent vaccine product candidate. The collaboration will explore the potential of various combinations of agents, including leveraging our GLAAS platform, with the goal to select the best potential immune therapy for patients. Each company will develop the products jointly through Phase 2 clinical trials, at which point Sanofi Pasteur intends to continue development of the most promising candidate and be responsible for commercialization. Sanofi Pasteur will bear the costs of all preclinical and clinical development, with Immune Design providing a specific formulation of GLA from the GLAAS platform at its cost through Phase 2 studies. Immune Design will be eligible to receive future milestone and royalty payments on any licensed product developed from the collaboration. We recognize funding from collaborative research and development efforts as revenue as we perform or deliver the related services in accordance with contract terms as long as we will receive payment for such services upon standard payment terms. The costs of the related services performed are recorded as research and development expenses on the consolidated statement of operations. For the years ended December 31, 2016 , 2015 and 2014 , we recognized $4.6 million , $4.2 million and $1.1 million , respectively, in revenue under this collaboration arrangement. As of December 31, 2016 and 2015 , we had an outstanding receivable of zero and $66,000 , respectively, and unearned revenue of $2.5 million and zero , respectively, under this collaboration arrangement.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Convertible Preferred Stock	Series C Convertible Preferred Stock Warrant Liability In October 2013, in connection with the issuance of our Series C convertible preferred stock, we issued fully exercisable warrants for the purchase of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share. All warrants were unexercised as of December 31, 2013. The estimated fair value for the 2013 warrants as of December 31, 2013 was $3.3 million . The fair value of the 2013 warrants was determined using the income method valuation model in combination with a Monte Carlo simulation in consideration of multiple early exercise triggers associated with the 2013 warrants. In April 2014, we amended the warrants to provide for their automatic net exercise if the IPO price exceeded the exercise price, immediately prior to the closing of the IPO. In July 2014, immediately prior to the closing of the IPO, warrants representing 996,940 shares of common stock were exercised for $8.1 million in cash, and warrants representing 978,592 shares of common stock were automatically net exercised for a total of 311,923 shares of common stock. Upon exercise of the warrants, the convertible preferred stock warrant liability was reclassified to stockholders’ equity (deficit). Convertible Preferred Stock In October 2013, we issued and sold 3,951,066 shares of our Series C convertible preferred stock at a price of $8.18 per share resulting in gross proceeds of $32.3 million , pursuant to a Series C convertible preferred stock and warrant purchase agreement. In connection with the issuance and sale of Series C convertible preferred stock we issued to the purchasers warrants, or 2013 warrants, to purchase an aggregate of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share. In connection with the completion of the Company’s IPO in July 2014, all outstanding shares of convertible preferred stock converted into 9,769,422 shares of common stock and all related warrants were exercised. See Note 9 for additional discussion of the exercise of the warrants.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Stockholders' Equity (Deficit)	Stockholders’ Equity (Deficit) Reverse Stock Split On July 14, 2014, we filed an amendment to our amended and restated certificate of incorporation, effecting a 1-for-8.175 reverse stock split. All issued and outstanding stock and per share amounts contained in our financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented. Initial Public Offering In July 2014, we completed an initial public offering (the IPO) of 5,000,000 shares of common stock at a price of $12.00 per share. In August 2014, we sold an additional 410,564 shares of common stock directly to our underwriters when they exercised portions of their over-allotment on two separate occasions at $12.00 per share. We received net proceeds of $57.8 million (inclusive of the exercise of the over-allotment) after deducting underwriting discounts and commissions and offering expenses totaling $7.1 million . In connection with the closing of the IPO, all outstanding shares of convertible preferred stock automatically converted into 9,769,422 shares of common stock. In July 2014, prior to the completion of the IPO, warrants to purchase 996,940 shares of common stock were exercised for $8.1 million in cash. Immediately prior to the closing of the IPO, warrants to purchase 978,592 shares were automatically net exercised, resulting in an issuance of an additional 311,923 shares of common stock. The significant number of shares issued in the third quarter of 2014 is expected to impact the year-over-year comparability of our net loss per share calculations through the third quarter of 2015. Upon completion of the IPO, the total shares of common stock authorized was 100,000,000 and the total shares of preferred stock authorized was 10,000,000 . Follow-On Public Offerings In April 2015, we closed an underwritten public offering of 3,000,000 shares of our common stock at a price of $26.50 per share. In May 2015, we sold an additional 47,409 shares directly to our underwriters when they exercised a portion of their option to purchase additional shares at $26.50 per share. We received net proceeds of $75.4 million (inclusive of the exercise of a portion of the underwriters’ option to purchase additional shares), after underwriting discounts and commissions and offering expenses totaling $5.4 million . In September 2016, we completed an underwritten follow-on public offering of 5,226,369 shares of common stock at a price of $6.25 per share. We received net proceeds of $30.3 million (inclusive of the exercise of a portion of the underwriters’ option to purchase additional shares), after underwriting discounts and commissions, and offering expenses totaling $2.4 million . Common Stock We had 25,413,055 and 20,153,202 shares of common stock outstanding as of December 31, 2016 and 2015 , respectively. Shares of common stock reserved for future issuance were as follows: AS OF DECEMBER 31, 2016 2015 Shares to be issued under the employee stock purchase plan 503,620 316,322 Shares to be issued upon exercise of outstanding stock options 3,697,643 2,832,467 Shares available for future stock option grants 724,723 804,553 Shares of common stock reserved for future issuance 4,925,986 3,953,342 Equity Incentive Plans 2014 Employee Stock Purchase Plan In April 2014, our board of directors adopted, and in July 2014 our stockholders approved, the 2014 Employee Stock Purchase Plan (2014 ESPP). The total number of shares of common stock available for issuance under the 2014 ESPP may increase annually on January 1 by (i) the lesser of 1% of the total number of shares issued and outstanding as of December 31 of the immediately preceding year or (ii) 200,000 shares, or less as deemed appropriate by the Board of Directors. For 2017, the Board of Directors determined the current shares available to be issued under the 2014 ESPP is sufficient, and did not increase the amount of authorized shares. 2008 Equity Incentive Plan and 2014 Omnibus Incentive Plan In 2008, we adopted the 2008 Equity Incentive Plan (2008 Plan) for eligible employees, officers, directors, and consultants, which provided for the grant of incentive and non-statutory stock options, restricted stock awards, restructured stock unit awards grant, and stock appreciation rights. The terms of the stock awards, including vesting requirements, were determined by the board of directors, subject to the provisions of the 2008 Plan. In April 2014, our board of directors adopted, and in July 2014 our stockholders approved, the 2014 Omnibus Incentive Plan (2014 Plan) which provides for the granting of certain awards to eligible employees, officers, directors, and consultants. Upon approval of the 2014 Plan by the stockholders in July 2014, 1,400,000 shares of our common stock were reserved for issuance under the 2014 Plan and we ceased granting stock awards under the 2008 Plan. All shares of common stock subject to awards under the 2008 Plan that expire, terminate, or are otherwise surrendered, canceled, forfeited or repurchased without having been fully exercised or resulting in the issuance of common stock become available for issuance under the 2014 Plan. Stock options granted under the 2008 and 2014 Plans generally vest within four years, and vested options are exercisable until ten years after the date of grant. Vesting of certain employee options may be accelerated in the event of a change in control of our company. We grant stock options to employees with exercise prices equal to the fair value of our common stock on the date of grant. There were a total of 2,926,850 shares of common stock authorized under the 2014 Plan as of December 31, 2016 . The total number of shares of common stock available for issuance under the 2014 Plan will automatically increase annually on January 1 by 4% of the total number of shares issued and outstanding as of December 31 of the immediately preceding year. On January 1, 2017, in accordance with the 2014 Plan and annual increase provisions, the authorized shares increased by 1,016,522 shares. Restricted Stock Units In 2016, we began issuing restricted stock units (RSUs) to employees under the 2014 Plan. The fair value of the RSUs is determined on the date of grant based on the market price of our common stock. RSUs are recognized as an expense ratably over the vesting period and our RSUs generally vest over four years with 25% of the total award vesting on each anniversary of the vesting commencement date. The activity for our RSUs is summarized as follow: Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2015 — — Granted 118,000 $ 19.39 Vested — $ — Forfeited (10,750 ) $ 19.39 Outstanding at December 31, 2016 107,250 $ 19.39 Stock Option Activity Summary stock option information is as follows: OPTIONS OUTSTANDING WEIGHTED- AVERAGE EXERCISE PRICE WEIGHTED- AVERAGE REMAINING CONTRACT TERM (IN YEARS) AGGREGATE INTRINSIC VALUE (IN THOUSANDS) Outstanding at January 1, 2015 1,907,091 $4.16 Granted 1,241,394 $21.55 Exercised (219,290 ) $1.38 Forfeited (96,728 ) $18.61 Expired — $— Outstanding at December 31, 2015 2,832,467 $11.48 8.24 $ 30,447 Granted 991,110 $15.49 Exercised (20,782 ) $3.12 Forfeited (182,605 ) $19.01 Expired (29,797 ) $25.65 Outstanding at December 31, 2016 3,590,393 $12.13 7.33 $ 5,062 Vested and expected to vest after December 31, 2016 3,453,099 $12.00 7.27 $ 5,043 Exercisable at December 31, 2016 1,903,268 $8.86 6.12 $ 4,493 As of December 31, 2016 , there was $15.6 million of total unrecognized stock-based compensation expense related to nonvested stock options that is expected to be recognized over a weighted-average period of 2.4 years. The total intrinsic value of options exercised during the years ended December 31, 2016 , 2015 and 2014 was $0.1 million , $5.0 million and $0.2 million , respectively. Stock-Based Compensation Expense Employee stock-based compensation expense recognized was calculated based on awards ultimately expected to vest and has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, as necessary, in subsequent periods if actual forfeitures differ from those estimates. Total stock-based compensation expense recognized in our statements of operations is as follows (in thousands): YEARS ENDED DECEMBER 31, 2016 2015 2014 Employee: Research and development $ 3,923 $ 2,034 $ 421 General and administrative 5,029 3,810 703 Non-Employee: Research and development 268 205 216 General and administrative 63 248 4 Total stock-based compensation expense $ 9,283 $ 6,297 $ 1,344 We use the Black-Scholes option pricing model to estimate the fair value of stock options at the grant date. The Black-Scholes option pricing model requires us to make certain estimates and assumptions, including assumptions related to the expected price volatility of our stock, the period during which the options will be outstanding, the rate of return on risk-free investments, and the expected dividend yield of our stock. To estimate the fair value of our common stock prior to our IPO, our board of directors periodically determined the per share fair value of our common stock at various dates using valuations performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation . Upon the completion of our IPO, the fair value of our common stock has been determined by the trading value of our common stock on NASDAQ. The fair values of stock options granted to employees were calculated using the following assumptions: YEARS ENDED DECEMBER 31, 2016 2015 2014 Weighted-average estimated fair value $10.07 $15.65 $9.32 Risk-free interest rate (1) 1.10% - 2.39% 1.50% - 1.86% 1.54% - 2.16% Expected term of options (in years) (2) 5.50 - 9.46 5.50 - 6.08 5.50 - 6.75 Expected stock price volatility (3) 77% - 93% 77% - 91% 90% - 93% Expected dividend yield (4) —% —% —% (1) The risk-free interest rate assumption was based on zero-coupon U.S. Treasury instruments that had terms consistent with the expected term of our stock option grants. (2) We used the “simplified method” for options to determine the expected term of our stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option. (3) Volatility is a measure of the amount by which a financial variable, such as share price, has fluctuated or is expected to fluctuate during a period. We analyzed the stock price volatility of companies at a similar stage of development to estimate expected volatility of our stock price. (4) We have never declared or paid cash dividends and do not presently plan to pay cash dividends in the foreseeable future.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes No provision for income taxes has been recorded for the years ended December 31, 2016 , 2015 and 2014 , due to the operating losses incurred since inception for which no benefit has been recorded. The reconciliation of the U.S. income tax rate to the effective income tax rate for continuing operations is as follows: AS OF DECEMBER 31, 2016 2015 Statutory tax rate 35.0 % 35.0 % Effect of: Permanent differences (1.5 ) (2.1 ) Other (0.4 ) 0.5 General business credits 2.4 4.1 Change in valuation allowance (35.5 ) (37.5 ) Effective tax rate — % — % Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred taxes are as follows (in thousands): AS OF DECEMBER 31, 2016 2015 Deferred tax assets: Net operating loss carryforwards $ 52,154 $ 39,965 Research and development credit 5,582 4,290 Depreciation and amortization 2,023 165 Other temporary differences 6,154 2,563 Gross deferred tax assets 65,913 46,983 Deferred tax asset valuation allowance (65,913 ) (46,983 ) Net deferred tax assets $ — $ — Realization of deferred tax assets is dependent on future earnings, if any, the timing and amount of which are uncertain. Accordingly, the deferred tax assets have been offset by a valuation allowance. The valuation allowance relates primarily to net deferred tax assets from operating losses and research and development credits. The net deferred tax asset has been fully offset by a valuation allowance. The valuation allowance increased by $18.9 million and $14.8 million during 2016 and 2015 , respectively. As of December 31, 2016 and 2015 , we had approximately $152.5 million and $117.6 million in federal net operating loss carryforwards and approximately $5.6 million and $4.3 million in federal research and development tax credit carryforwards, respectively. The net operating losses and federal research and development credits will begin to expire in varying amounts between 2028 and 2036 if not utilized. The Tax Reform Act of 1986 (the Act) provides for a limitation on the annual use of net operating loss and research and development tax credit carryforwards following certain ownership changes (as defined by the Act) that could limit our ability to utilize these carryforwards. We may have experienced an ownership change, as defined by the Act, as a result of past financings. Accordingly, our ability to utilize the aforementioned carryforwards may be limited. Additionally, U.S. tax laws limit the time during which these carryforwards may be applied against future taxes; therefore, we may not be able to take full advantage of these carryforwards for federal income tax purposes. Certain net operating losses arise from the deductibility for tax purposes of stock-based compensation equal to the difference between the fair value of the stock on the date of exercise and the exercise price of the stock. For financial reporting purposes, the tax effect of this deduction when recognized is accounted for as a credit to stockholders’ equity. Through December 31, 2016, we had approximately $3.5 million of excess tax deductions on option exercises. We file income tax returns in the U.S. federal jurisdiction as well as the state of California. We are not currently under audit in any tax jurisdiction. Tax years from 2008 through 2016 are currently open for audit by federal and state taxing authorities. We recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. During the years ended December 31, 2016 and 2015 , we did not recognize any accrued interest or penalties associated with unrecognized benefits. Additionally, we did not record any unrecognized tax benefits at December 31, 2016 and 2015 .

Legal Proceedings

Legal Proceedings	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	Legal Proceedings TheraVectys SA v. Immune Design Corp. On October 17, 2016, we entered into a Settlement Agreement and a License Agreement with TheraVectys SA (TVS) obtaining certain present and future intellectual property rights and resolving the litigation that TVS initiated against us in the Chancery Court of the State of Delaware in July 2014, as well as related claims and counterclaims. In the proceeding, TVS had alleged that it had entered into a contractual relationship with Henogen SA (Henogen) in 2010 with respect to the production of lentiviral vector vaccines for TVS. Henogen is a contract manufacturing organization with which we contracted for the manufacture of our LV305 product candidate. TVS alleged that its contractual relationship with Henogen contained an exclusivity provision limiting Henogen’s ability to participate in the manufacturing process of a vaccine based on lentiviral DNA vectors for third parties, as well as a provision preventing Henogen from sharing or using certain TVS confidential technology for manufacturing processes developed by TVS with or for the benefit of others. TVS alleged that we entered into a contractual relationship with Henogen in 2012 to manufacture lentiviral vectors for vaccines, which TVS contends interfered with its contract with Henogen and resulted in the use of certain TVS confidential information and trade secrets. In addition, the complaint alleged that we obtained shipments of lentiviral vectors for vaccines from Henogen and conducted clinical trials with these lentiviral vectors. The complaint asserted four counts for relief: tortious interference with contractual relationship, unfair competition, misappropriation of trade secrets, and unjust enrichment. Claimed damages were not specified. Under the Settlement Agreement, TVS agreed to dismiss all pending litigation brought by TVS against us and to withdraw patent opposition proceedings (EPO Proceeding) brought by TVS against our European Patent No EP 2 456 786 (EU Patent). Also under the Settlement Agreement, both parties agreed to a broad release of claims against one another based on acts or omissions arising out of the litigation, or the facts and circumstances giving rise to the litigation. Neither party made any admission of liability or wrongdoing under the Settlement Agreement. As a non-contingent fee for a license to certain present and future intellectual property of TVS, and in consideration for the settlement of all claims and disputes between the parties, we have paid $6.0 million into an escrow account (Escrowed Payment), and we have also agreed to pay $1.25 million to TVS when we next raise $25.0 million , in the aggregate, through equity sales, debt or licensing revenue. The Escrowed Payment will be disbursed to TVS as follows: (a) fifty percent ( 50% ) when (i) Institut Pasteur consents to the granting by TVS to us of a sublicense to certain patents licensed by TVS (or to be licensed by TVS) from Institut Pasteur and (ii) the litigation in the United States and Belgium has been dismissed; and (b) fifty percent ( 50% ) upon the final resolution of the EPO Proceeding if the scope of the EU Patent remains unchanged (Escrow Conditions); provided, that the events described in item (a) are a condition to the release of any portion of the Escrowed Payment to TVS, and delays in satisfying the Escrow Conditions may potentially result in a reduction of the amount of the Escrowed Payment that is disbursed to TVS. Currently, we believe that items (a)(i) and (b) of the Escrow Conditions have been satisfied. In addition, the License Agreement provides us with a field limited, non-exclusive, sublicensable license for oncology uses to certain current and future intellectual property rights owned, controlled and licensed by TVS. For licensed products developed under the License Agreement, we would be obligated to pay certain development and commercial milestones and royalties. We determined that the aggregate payment amount expected to be paid to TVS is $7.25 million and as such, the aggregate payment amount should be allocated between (1) dismissal of the litigation; and (2) license to current and future TVS intellectual property (IP). As we are not able to reliably estimate the fair value of the litigation dismissal, we assigned a fair value to the aggregate amount of the license to current and future TVS IP through the use of a benchmarking approach and determined the fair value of the license to current and future IP obtained from TVS by benchmarking this deal against similar recent (within the last 5 years) deals within our industry. The metrics we used in our benchmarking approach included similarities in industry, product type, therapeutic area, stage of product development and exclusivity. Based upon the results of our benchmark approach, we determined that the fair value assigned to the license to current and future TVS IP to be $1.4 million with the remaining residual amount of $5.85 million allocated to the dismissal of the litigation. For the year ended December 31, 2016, the $5.85 million allocated to the dismissal of litigation is recorded as a general and administrative expense and the $1.4 million allocated to the license acquired for current and future TVS IP granted to us is recorded as a research and development expense on the consolidated statements of operations. European Patent Opposition In February 2013, a third party filed an opposition at the European Patent Office (EPO) requesting revocation of European Patent No. 2068918 directed to GLA formulations and uses. This patent is owned by Infectious Disease Research Institute (IDRI) and under license to us. The oral proceedings for this opposition were held in September 2016. At the oral proceedings, the EPO maintained the patent in an amended form, which continues to cover the GLAAS products being developed by us and our licensees. We and the opponent have filed a notice of appeal, and the outcome of an appeal to this proceeding will not be known for several years.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plan	Employee Benefit Plan We sponsor a 401(k) defined contribution plan for our employees. Employee contributions are voluntary. We may match employee contributions in amounts to be determined at our sole discretion. Currently, we have elected to satisfy the safe-harbor rules by matching contributions equal to 100% of employee salary deferrals that do not exceed 3% of the employee’s compensation, plus 50% matching employee salary deferrals between 3% and 5% of the employee’s compensation. Employer contributions have totaled approximately $243,000 , $214,000 , and $153,000 for the years ended December 31, 2016 , 2015 and 2014 respectively.

Selected Quarterly Financial In

Selected Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (Unaudited)	Selected Quarterly Financial Information (Unaudited) The following amounts are in thousands, except per share amounts: Quarter Ended March 31, June 30, September 30, December 31, (unaudited) Total revenues 1,863 1,133 8,206 2,058 Net loss $ (12,294 ) $ (14,347 ) $ (12,443 ) $ (14,446 ) Basic and diluted net loss per share $ (0.61 ) $ (0.71 ) $ (0.60 ) $ (0.57 ) Quarter Ended March 31, June 30, September 30, December 31, (unaudited) Total revenues 1,938 1,780 4,653 1,139 Net loss $ (9,406 ) $ (10,517 ) $ (7,407 ) $ (12,115 ) Basic and diluted net loss per share $ (0.56 ) $ (0.54 ) $ (0.37 ) $ (0.60 )

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP). To conform with GAAP, the preparation of our financial statements requires management to make judgments, assumptions, and estimates that affect the amounts reported in our financial statements and accompanying notes. Estimates are used for, but not limited to, accruals for clinical trial activity, other accrued liabilities, and assumptions used in determining stock-based compensation expenses and convertible preferred stock warrant liability. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable. Actual results could differ materially from those estimates.
Principles of Consolidation	Principles of Consolidation Our consolidated financial statements include the financial position and results of operations of Immune Design Corp. and Immune Design Ltd., our wholly owned subsidiary. Immune Design Ltd. was incorporated in the United Kingdom in February 2016 and to date there have been no financial transactions or balances related to this entity.
Segments	Segments We operate in one segment and use cash flow as the primary measure to manage our business and do not segment the business for internal reporting or decision-making purposes.
Offering Costs	Offering Costs Offering costs represent legal, accounting and other direct costs related to our efforts to raise capital through our follow-on public offerings in September 2016 and April 2015 and for our initial public offering (IPO) in July 2014. These costs were deferred until completion of the follow-on public offerings and IPO, respectively, at which time they were reclassified to additional paid-in capital as a reduction of the proceeds.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are highly liquid investments with a maturity of 90 days or less at the date of purchase and primarily consist of investments in money market funds. In addition, we maintain cash balances with financial institutions in excess of insured limits and do not anticipate any losses on such cash balances.
Concentration of Risk	Concentration of Risk We limit our credit risk associated with cash and cash equivalents by placing our deposits with banks we believe are highly creditworthy and our investments with highly rated money market funds.
Short-term investments	Short-Term Investments Our short-term investments include funds invested in U.S. Treasury securities with a final maturity of each security of less than one year. All investments are classified as available-for-sale securities and are recorded at fair value based on quoted prices in active markets, with unrealized gains and losses excluded from earnings and reported in other comprehensive income (loss). Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Realized gains and losses and declines in fair value that are deemed to be other than temporary are reflected in the condensed consolidated statements of operations and comprehensive income (loss) using the specific-identification method.
Accounts Receivable	Accounts Receivable Accounts receivable are amounts due from other companies related primarily to licensing fees, product sales and research and development services. We considered the need for an allowance for doubtful accounts and have concluded that no allowance was needed as of December 31, 2016 or 2015 , as the estimated risk of loss on our accounts receivable was determined to be minimal.
Inventory	Inventory Inventory is recorded at the lower of cost or market. Cost includes amounts related to materials and labor, and is determined on a specific identification basis in a manner which approximates the first-in, first-out method. We record adjustments to inventory for potentially excess, obsolete, expired, or impaired items.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over an estimated useful life that is generally three years , while leasehold improvements are amortized over the shorter of their estimated useful lives or the related lease term. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is credited or charged to operations. Maintenance and repairs are expensed as incurred. Asset improvements are capitalized.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets might not be recoverable. Conditions that would necessitate an impairment assessment include a significant decline in the observable market value of an asset, a significant change in the extent or manner in which an asset is used, or any other significant adverse change that would indicate that the carrying amount of an asset is not recoverable.
Accrued Liabilities	Accrued Liabilities Accrued liabilities represent accrued compensation including vacation accruals, unearned revenue and accrued expenses. As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued professional services and research and development expenses. This process involves reviewing contracts and vendor agreements, communicating with our applicable personnel to identify services that have been performed on our behalf. We estimate the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual cost. We make estimates of our accrued expenses as of each balance sheet date in our consolidated financial statements based on facts and circumstances known to us. We base our expenses related to contract manufacturing and clinical trials on our estimates of the services received and efforts expended pursuant to contracts with multiple contract manufacturing organizations and clinical research organizations that conduct and manage supply and clinical trials on our behalf. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period. To date, we have not experienced any significant adjustments to our estimates.
Leases and Deferred Rent	Leases and Deferred Rent We have entered into lease agreements for laboratory and office facilities. These leases are classified as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facilities leases, including allowances to fund leasehold improvements and rent escalations are accrued as deferred rent. Leasehold improvements funded by the lessor are capitalized and are recognized as reductions to rental expense on a straight-line basis over the term of the lease.
Series C Convertible Preferred Stock Warrant Liability	Series C Convertible Preferred Stock Warrant Liability We account for our warrants in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 480-10, Distinguishing Liabilities from Equity , which requires that a financial instrument, other than an outstanding share, that, at inception, includes an obligation to repurchase the issuer’s equity shares regardless of the timing or likelihood of the redemption, shall be classified as a liability. We measure the fair value of the warrant liability based on the fair value of the warrants which we determine based on an allocation of our enterprise value to all classes of equity and preferred stock, including the warrants. In valuing the warrants, we utilized the income method approach in combination with a Monte Carlo simulation, which is a method that evaluates many possible value outcomes to establish the expected value of an asset. This methodology allows the modeling of securities with complex terms, such as the warrants, where path dependency, floors, caps, triggers, changes of control and down round financing provisions can be taken into account. In each reporting period, we record any change in fair value of the warrants as a non-operating gain or loss in the consolidated statements of operations.
Revenue Recognition	Revenue Recognition We derive our revenue from collaboration and licensing agreements and the sale of products associated with material transfer, collaboration and supply agreements. Licensing fees, are recognized when the amounts are earned and determinable during the applicable period. We recognize up-front nonrefundable license fees when due under contractual agreements and when we do not have a continuing obligation to provide services related to the agreement. Revenue associated with nonrefundable up-front license fees under arrangements where the license fees and research and development activities cannot be accounted for as separate units of accounting is deferred and recognized as revenue on a straight-line basis over the expected term of our continued involvement in the research and development process. Revenues from the achievement of research and development milestones, if deemed substantive, are recognized as revenue when the milestones are achieved, and the milestone payments are due and collectible. If not deemed substantive, we recognize such milestones as revenue on a straight-line basis over the remaining expected term of continued involvement in the research and development process. Milestones are considered substantive if all of the following conditions are met: (1) the milestone is nonrefundable, (2) achievement of the milestone was not reasonably assured at the inception of the arrangement, (3) substantive effort is involved to achieve the milestone and (4) the amount of the milestone appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone and any ongoing research and development or other services are priced at fair value. Payments received in advance of work performed are recorded as unearned revenue. Certain agreements from which we derive our revenue include multiple deliverables. We recognize the revenue for each deliverable at fair value determined to be the estimated selling price in cases when neither vendor specific objective evidence nor third-party evidence is available. Revenue is recognized when all of the following criteria are met: (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the price to the customer is fixed or determinable and (4) collectability is reasonably assured. The evaluation of these revenue recognition criteria requires significant management judgment. For instance, we use judgment to assess collectability based on factors such as the customer’s creditworthiness and past collection history, if applicable. If we determine that collection of a payment is not reasonably assured, revenue recognition is deferred until receipt of payment. We also use judgment to assess whether a price is fixed or determinable including, but not limited to, reviewing contractual terms and conditions related to payment terms. Revenue from product sales of glucopyranosyl lipid A (GLA), a product from our GLAAS platforms, is recognized when the risk of loss has passed to the customer or deferred until such time that risk of loss has passed. All revenues associated from the sale of GLA products supplied by us are reported under product sales with the applicable costs reported under cost of product sales. Product sales consist of the direct costs associated with the manufacture and formulation of GLA, including costs to purchase raw materials, third-party contract manufacturing costs, assay testing and ongoing product stability testing. We consider significant revenue concentrations to be customers who account for 10% or more of total revenues generated by us during the periods presented.
Stock-Based Compensation	Stock-Based Compensation We account for stock-based compensation under the fair value method. Stock-based compensation costs related to employees and directors is measured at the grant date, based on the fair-value-based measurement of the award estimated using the Black-Scholes option-pricing model, and is recognized as expense over the requisite service period on a straight-line basis. Options granted to non-employee service providers are accounted for at estimated fair value using the Black-Scholes option-pricing model and are remeasured over the vesting term as earned. We recognize compensation expense for only the portion of options expected to vest. Therefore, management applied an estimated forfeiture rate that was derived from historical employee termination behavior. If the actual number of forfeitures differs from these estimates, adjustments to compensation expense may be required in future periods.
Research and Development	Research and Development Research and development costs are expensed as incurred. Research and development costs primarily include personnel costs, materials and manufacturing to support clinical trials, fees paid to consultants and outside service providers, costs to conduct clinical trials and allocated overhead. Amounts incurred in connection with collaboration agreements are also included in research and development expense. Payments made prior to the receipt of goods or services to be used in research and development are deferred until the goods or services are received.
Income Taxes	Income Taxes Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and the operating loss and tax credit carry forwards. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets and liabilities are measured at the balance sheet date using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period such tax rate changes are enacted. Our net deferred tax asset has been fully offset by a valuation allowance because of our history of losses. Any potential accrued interest and penalties related to unrecognized tax benefits within operations would be recorded as income tax expense. To date, there have been no interest or penalties charged to us related to the underpayment of income taxes.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is composed of net loss and other comprehensive income or loss that are excluded from net loss. For the year ended December 31, 2016, other comprehensive loss consists of unrealized losses on our available-for-sale securities. For the years ended December 31, 2015 and 2014, there was no difference between comprehensive loss and net loss.
Subsequent Events	Subsequent Events We consider events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, FASB issued an Accounting Standards Update (ASU) amending revenue recognition guidance and requiring more detailed disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. In August 2015, the FASB deferred the effective date of the revenue recognition guidance to reporting periods beginning after December 15, 2017. The new standard permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). We currently anticipate adopting the new standard effective January 1, 2018, using the modified retrospective method. We will continue to monitor additional modifications, clarifications or interpretations undertaken by the FASB that may impact our current conclusions. While we are still in the process of completing our impact assessment, we do not currently anticipate a material impact on our financial position and results of operations. In February 2016, FASB issued ASU 2016-02 related to lease accounting. This standard will require organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases that are greater than 12 months in duration. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from previous GAAP. There continues to be a differentiation between finance leases and operating leases, however, the principal difference from previous guidance is that the lease assets and lease liabilities arising from operating leases will be recognized on the balance sheets. For capital or finance leases, lessees will recognize amortization of the right-of-use asset separately from interest on the lease liability. For operating leases, lessees will recognize a single total lease expense. The standard is effective for public companies for the fiscal years and interim reporting periods beginning after December 15, 2018. We are evaluating the guidance to determine the potential impact on our results of operations, financial condition, cash flows, and financial statement disclosures. In March 2016, the FASB issued ASU No. 2016-09 that relates to share-based payments. The amendments in this update simplify several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, statutory tax withholding requirements, as well as classification within the statement of cash flows. The guidance will be effective for the annual periods beginning after December 15, 2016, and interim periods within those annual periods. The Company is currently evaluating the impact of the new pronouncement on its financial statements . In August 2016, the FASB issued ASU No. 2016-15 which provides new guidance on the classification of certain cash receipts and payments in the statement of cash flows. The new guidance is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The Company will be required to adopt the new guidance beginning with its first fiscal quarter of 2018; early adoption is permitted. The Company is currently assessing the impact that the new guidance will have on its consolidated statements of cash flows. In November 2016, the FASB issued ASU No. 2016-18 that relates to restricted cash. The new guidance requires amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The Company will be required to revise its consolidated statements of cash flows to adopt the new guidance beginning with its first fiscal quarter of 2018; early adoption is permitted. Adoption of the new guidance will not impact the Company's financial position and results of operations.
Net Loss Per Share	Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Because of net losses recognized in each period, potential common shares issuable upon the exercise of outstanding stock options and warrants and the conversion of preferred shares in the IPO into common shares have not been reflected in the calculation of diluted net loss per share due to the anti-dilutive effect. Diluted net loss per share, therefore, does not differ from basic net loss per share.
Fair Value Measurement	We measure and record cash and cash equivalents and convertible preferred stock warrant liabilities at fair value in the accompanying financial statements. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value, is as follows: Level 1 : Quoted prices in active markets for identical assets or liabilities. Level 2 : Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 : Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 1 securities consist of highly liquid money market funds. The fair value of Level 1 assets has been determined using quoted prices in active markets for identical assets. In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. Prior to the closing of our IPO in 2014, our preferred stock warrant liability was classified within Level 3 and was measured at its estimated fair value on a recurring basis using the income method approach in combination with a Monte Carlo simulation. Inputs used to determine estimated fair value included the estimated fair value of the underlying stock at the valuation measurement date, the multiple scenarios outlining probabilities and the remaining contractual term of the warrants, risk-free interest rates, expected dividends, and the expected volatility of the price of the underlying stock.

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The common stock equivalents issuable upon the conversion or exercise of the following dilutive securities has been excluded from the computation of diluted net loss per share attributable to common stockholders calculation because their effect would have been anti-dilutive for the periods presented: DECEMBER 31, 2016 2015 2014 Outstanding options to purchase common stock 3,590,393 2,832,467 1,907,091 Unvested restricted stock units 107,250 — — 3,697,643 2,832,467 1,907,091

Cash Equivalents and Short-Te27

Cash Equivalents and Short-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Cash, Cash Equivalents and Investments	The amortized cost and fair value of our cash equivalents and short-term investments at December 31, 2016 are as follows (in thousands): December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 36,412 $ 2 $ — $ 36,414 U.S. Treasury securities 62,066 2 (28 ) 62,040 Total $ 98,478 $ 4 $ (28 ) $ 98,454 Classified as: Cash equivalents $ 36,414 Short-term investments 62,040 Total $ 98,454

Fair Value of Financial Instr28

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis (in thousands): December 31, 2016 LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds $ 36,414 $ — $ — $ 36,414 U.S. Treasury securities 62,040 — — 62,040 Total $ 98,454 $ — $ — $ 98,454 December 31, 2015 LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds $ 110,657 $ — $ — $ 110,657
Reconciliation of Convertible Preferred Stock Warranty Liability Measured and Recorded at Fair Value on a Recurring Basis	The following table shows the reconciliation of the convertible preferred stock warrant liability measured and recorded at fair value on a recurring basis, using significant unobservable inputs (Level 3) (in thousands): ESTIMATED FAIR VALUE Balance as of December 31, 2013 3,336 Change in fair value of convertible preferred stock warrant liability 4,277 Conversion of preferred stock warrant liability into additional-paid-in-capital (7,613 ) Balance as of December 31, 2014 $ —

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory	Inventory consists of the following (in thousands): DECEMBER 31, 2016 2015 Raw materials $ 567 $ — Finished goods 40 13 Total inventory $ 607 $ 13

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property and equipment consists of the following (in thousands): DECEMBER 31, 2016 2015 Laboratory equipment $ 2,330 $ 2,287 Leasehold improvements 156 129 Computer equipment and software 483 448 Office equipment, furniture, and fixtures 174 160 Total 3,143 3,024 Less: accumulated depreciation and amortization (2,729 ) (2,439 ) Total property and equipment, net $ 414 $ 585

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): DECEMBER 31, 2016 2015 Research and development services $ 3,027 $ 2,043 Legal and professional services 28 378 Employee compensation 1,880 1,538 Total accrued liabilities $ 4,935 $ 3,959

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Future minimum lease payments	As of December 31, 2016 , future minimum lease payments are as follows (in thousands): 2017 $ 1,448 2018 1,486 2019 1,525 2020 1,203 2021 1,200 Total future minimum lease payments $ 6,862

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Schedule of Shares of Common Stock Reserved for Future Issuance	Shares of common stock reserved for future issuance were as follows: AS OF DECEMBER 31, 2016 2015 Shares to be issued under the employee stock purchase plan 503,620 316,322 Shares to be issued upon exercise of outstanding stock options 3,697,643 2,832,467 Shares available for future stock option grants 724,723 804,553 Shares of common stock reserved for future issuance 4,925,986 3,953,342
Schedule of Restricted Stock Units	The activity for our RSUs is summarized as follow: Shares Weighted Average Grant Date Fair Value Outstanding at December 31, 2015 — — Granted 118,000 $ 19.39 Vested — $ — Forfeited (10,750 ) $ 19.39 Outstanding at December 31, 2016 107,250 $ 19.39
Summary of Stock Options	Summary stock option information is as follows: OPTIONS OUTSTANDING WEIGHTED- AVERAGE EXERCISE PRICE WEIGHTED- AVERAGE REMAINING CONTRACT TERM (IN YEARS) AGGREGATE INTRINSIC VALUE (IN THOUSANDS) Outstanding at January 1, 2015 1,907,091 $4.16 Granted 1,241,394 $21.55 Exercised (219,290 ) $1.38 Forfeited (96,728 ) $18.61 Expired — $— Outstanding at December 31, 2015 2,832,467 $11.48 8.24 $ 30,447 Granted 991,110 $15.49 Exercised (20,782 ) $3.12 Forfeited (182,605 ) $19.01 Expired (29,797 ) $25.65 Outstanding at December 31, 2016 3,590,393 $12.13 7.33 $ 5,062 Vested and expected to vest after December 31, 2016 3,453,099 $12.00 7.27 $ 5,043 Exercisable at December 31, 2016 1,903,268 $8.86 6.12 $ 4,493
Schedule of Stock-Based Compensation Expense Recognized	Total stock-based compensation expense recognized in our statements of operations is as follows (in thousands): YEARS ENDED DECEMBER 31, 2016 2015 2014 Employee: Research and development $ 3,923 $ 2,034 $ 421 General and administrative 5,029 3,810 703 Non-Employee: Research and development 268 205 216 General and administrative 63 248 4 Total stock-based compensation expense $ 9,283 $ 6,297 $ 1,344
Schedule of Fair Value of Stock Options Granted to Employees	The fair values of stock options granted to employees were calculated using the following assumptions: YEARS ENDED DECEMBER 31, 2016 2015 2014 Weighted-average estimated fair value $10.07 $15.65 $9.32 Risk-free interest rate (1) 1.10% - 2.39% 1.50% - 1.86% 1.54% - 2.16% Expected term of options (in years) (2) 5.50 - 9.46 5.50 - 6.08 5.50 - 6.75 Expected stock price volatility (3) 77% - 93% 77% - 91% 90% - 93% Expected dividend yield (4) —% —% —% (1) The risk-free interest rate assumption was based on zero-coupon U.S. Treasury instruments that had terms consistent with the expected term of our stock option grants. (2) We used the “simplified method” for options to determine the expected term of our stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option. (3) Volatility is a measure of the amount by which a financial variable, such as share price, has fluctuated or is expected to fluctuate during a period. We analyzed the stock price volatility of companies at a similar stage of development to estimate expected volatility of our stock price. (4) We have never declared or paid cash dividends and do not presently plan to pay cash dividends in the foreseeable future.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of the U.S. income tax rate to the effective income tax rate for continuing operations is as follows: AS OF DECEMBER 31, 2016 2015 Statutory tax rate 35.0 % 35.0 % Effect of: Permanent differences (1.5 ) (2.1 ) Other (0.4 ) 0.5 General business credits 2.4 4.1 Change in valuation allowance (35.5 ) (37.5 ) Effective tax rate — % — %
Schedule of Deferred Tax Assets and Liabilities	Significant components of our deferred taxes are as follows (in thousands): AS OF DECEMBER 31, 2016 2015 Deferred tax assets: Net operating loss carryforwards $ 52,154 $ 39,965 Research and development credit 5,582 4,290 Depreciation and amortization 2,023 165 Other temporary differences 6,154 2,563 Gross deferred tax assets 65,913 46,983 Deferred tax asset valuation allowance (65,913 ) (46,983 ) Net deferred tax assets $ — $ —

Selected Quarterly Financial 35

Selected Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The following amounts are in thousands, except per share amounts: Quarter Ended March 31, June 30, September 30, December 31, (unaudited) Total revenues 1,863 1,133 8,206 2,058 Net loss $ (12,294 ) $ (14,347 ) $ (12,443 ) $ (14,446 ) Basic and diluted net loss per share $ (0.61 ) $ (0.71 ) $ (0.60 ) $ (0.57 ) Quarter Ended March 31, June 30, September 30, December 31, (unaudited) Total revenues 1,938 1,780 4,653 1,139 Net loss $ (9,406 ) $ (10,517 ) $ (7,407 ) $ (12,115 ) Basic and diluted net loss per share $ (0.56 ) $ (0.54 ) $ (0.37 ) $ (0.60 )

Description of the Business - N

Description of the Business - Narrative (Details)	12 Months Ended
	Dec. 31, 2016platform
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of discovery platforms	2

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Segments (Details)	12 Months Ended
	Dec. 31, 2016segment
Accounting Policies [Abstract]
Number of operating segments	1

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Accounts Receivable (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Allowance for doubtful accounts receivable	$ 0	$ 0

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Estimated useful lives	3 years

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Revenue Recognition (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Collaboration Partner One [Member] | Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	64.00%	44.00%	55.00%
Collaboration Partner Two [Member] | Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	35.00%	36.00%	28.00%
Collaboration Partner Three [Member] | Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	1.00%	20.00%	16.00%
Collaboration Partners [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	100.00%	98.00%

Net Loss Per Share (Details)

Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,697,643	2,832,467	1,907,091
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,590,393	2,832,467	1,907,091
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	107,250	0	0

Cash Equivalents and Short-Te42

Cash Equivalents and Short-Term Investments (Details) $ in Thousands	Dec. 31, 2016USD ($)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 98,478
Gross Unrealized Gains	4
Gross Unrealized Losses	(28)
Fair Value	98,454
Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	36,412
Gross Unrealized Gains	2
Gross Unrealized Losses	0
Fair Value	36,414
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	62,066
Gross Unrealized Gains	2
Gross Unrealized Losses	(28)
Fair Value	62,040
Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	36,414
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 62,040

Fair Value of Financial Instr43

Fair Value of Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 98,454
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	36,414	$ 110,657
Fair Value	62,040
Total	98,454
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	36,414	110,657
Fair Value	62,040
Total	98,454
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Fair Value	0
Total	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	$ 0
Fair Value	0
Total	$ 0

Fair Value of Financial Instr44

Fair Value of Financial Instruments - Reconciliation of Convertible Preferred Stock Warranty Liability Measured and Recorded at Fair Value on a Recurring Basis (Details) - Preferred Stock Warrant Liability [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2014USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 3,336
Change in fair value of convertible preferred stock warrant liability	4,277
Conversion of preferred stock warrant liability into additional-paid-in-capital	(7,613)
Ending balance	$ 0

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 567	$ 0
Finished goods	40	13
Total inventory	$ 607	$ 13

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 3,143	$ 3,024
Less: accumulated depreciation and amortization	(2,729)	(2,439)
Total property and equipment, net	414	585
Depreciation and amortization	304	243	$ 238
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	2,330	2,287
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	156	129
Less: accumulated depreciation and amortization	(123)	(92)
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	483	448
Office equipment, furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 174	$ 160

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Research and development services	$ 3,027	$ 2,043
Legal and professional fees	28	378
Employee compensation	1,880	1,538
Total accrued liabilities	$ 4,935	$ 3,959

Series C Convertible Preferre48

Series C Convertible Preferred Stock Warrant Liability (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 31, 2013
Class of Warrant or Right [Line Items]
Fair value of warrants outstanding					$ 3,300
Proceeds from warrant exercises		$ 0	$ 0	$ 8,150
Convertible preferred Stock, Series C [Member]
Class of Warrant or Right [Line Items]
Number of warrants exercisable (in shares)						1,975,532
Warrant exercise price (in USD per share)						$ 8.175
Number of warrants exercised (in shares)	996,940
Warrants Exercised for Cash [Member]
Class of Warrant or Right [Line Items]
Number of warrants exercised (in shares)	996,940
Proceeds from warrant exercises	$ 8,100
Net Exercised Warrants [Member]
Class of Warrant or Right [Line Items]
Number of warrants exercised (in shares)	978,592
Common stock [Member]
Class of Warrant or Right [Line Items]
Stock issued during period (in shares)	311,923

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details)	1 Months Ended				12 Months Ended
	Jan. 31, 2016USD ($)ft²	Dec. 31, 2015USD ($)	Jul. 31, 2015USD ($)	Jan. 31, 2015USD ($)ft²	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Other Commitments [Line Items]
Leasehold improvements		$ 129,000			$ 156,000	$ 129,000
Accumulated depreciation		2,439,000			2,729,000	2,439,000
Square footage leased | ft²	20,133			9,640
Term of lease	5 years
Optional lease extension period	3 years			5 years
Annual base rent	$ 1,100,000
Annual increase in base rent, percent	2.50%
Funds drawn on letter of credit					0
Rent expense					713,000	849,000	$ 576,000
Collaborative Arrangement [Member] | ZVex Product [Member]
Other Commitments [Line Items]
Potential future milestone payments, up to					2,000,000
Collaborative Arrangement [Member] | NanoPass Technologies LTD [Member] | Intradermal Delivery Device [Member]
Other Commitments [Line Items]
Collaborative arrangement, license fee		500,000	$ 600,000
Collaborative arrangement, non-refundable deposit			$ 150,000
Potential future milestone payments, up to					8,800,000
Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member] | GLA/SLA First Exclusive Product [Member]
Other Commitments [Line Items]
Potential future milestone payments, up to					2,300,000
Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member] | GLA/SLA Subsequent Exclusive Products [Member]
Other Commitments [Line Items]
Potential future milestone payments, up to					1,100,000
Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member] | GLA/SLA First Non-Exclusive Product [Member]
Other Commitments [Line Items]
Potential future milestone payments, up to					1,300,000
Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member] | GLA/SLA Subsequent Non-Exclusive Products [Member]
Other Commitments [Line Items]
Potential future milestone payments, up to					625,000
Financial Standby Letter of Credit [Member]
Other Commitments [Line Items]
Letter of credit provided as security deposit	$ 200,000			$ 121,000
Leasehold improvements [Member]
Other Commitments [Line Items]
Accumulated depreciation		$ 92,000			$ 123,000	$ 92,000

Commitments and Contingencies50

Commitments and Contingencies - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,017	$ 1,448
2,018	1,486
2,019	1,525
2,020	1,203
2,021	1,200
Total future minimum lease payments	$ 6,862

License and Collaboration Agr51

License and Collaboration Agreements - Narrative (Details)	1 Months Ended			8 Months Ended	12 Months Ended
	Oct. 31, 2016USD ($)payment	Dec. 31, 2015USD ($)	Nov. 30, 2015USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2016USD ($)license_agreement	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2009USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development					$ 45,134,000	$ 33,087,000	$ 22,746,000
TheraVectys SA [Member] | Collaborative Arrangement [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments	$ 5,750,000
Number of milestone payments waived | payment	2
GLAAS Discovery Platform [Member] | Sanofi [Member] | Collaborative Arrangement, Product [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized					7,000,000	1,000,000	3,500,000
Milestone receivables					160,000,000
GLAAS Discovery Platform [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development			$ 250,000
GLA [Member] | MedImmune LLC [Member] | Collaborative Arrangement, Product [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized					0	2,500,000	1,000,000
GLA [Member] | MedImmune LLC [Member] | Collaborative Arrangement, Product [Member] | Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone receivables					62,900,000
GLA [Member] | MedImmune LLC [Member] | Collaborative Arrangement, Product [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone receivables					72,500,000
GLA [Member] | Medicago Inc [Member] | Collaborative Arrangement, Product [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized				$ 500,000
Milestone receivables					9,500,000
GLA [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development					925,000	2,900,000	500,000
First GLAAS Discovery Platform Product [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments			250,000
Subsequent GLAAS Discovery Platform Products [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments			$ 125,000
GLA/SLA Product [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development		$ 2,300,000
GLA/SLA First Exclusive Product [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments					2,300,000
GLA/SLA Subsequent Exclusive Products [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments					1,100,000
GLA/SLA First Non-Exclusive Product [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments					1,300,000
GLA/SLA Subsequent Non-Exclusive Products [Member] | Infectious Disease Research Institute [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments					$ 625,000
Dendritic Cell-targeted Theraputic and Prophylactic Immunization Strategies [Member] | California Institute of Technology [Member] | Collaborative Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of license agreements | license_agreement					2
Potential future milestone payments					$ 1,600,000
Annual license fee								$ 25,000
Dendritic Cell-targeted Theraputic and Prophylactic Immunization Strategies [Member] | California Institute of Technology [Member] | Collaborative Arrangement [Member] | Common stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Value of common stock issued for license								$ 25,000
Herpes Simplex Virus [Member] | Sanofi Pasteur [Member] | Collaborative Arrangement, Product [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable		66,000			0	66,000
Unearned receivable		$ 0			2,500,000	0
Herpes Simplex Virus [Member] | Sanofi Pasteur [Member] | Collaborative Arrangement, Product [Member] | Collaboration Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized					$ 4,600,000	$ 4,200,000	$ 1,100,000

Convertible Preferred Stock (De

Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Jul. 31, 2014	Oct. 31, 2013	Sep. 30, 2016	Apr. 30, 2015
Series C convertible preferred stock [Member]
Class of Stock [Line Items]
Issuance of convertible preferred stock (in shares)		3,951,066
Share price (in USD per share)		$ 8.18
Issuance of convertible preferred stock		$ 32.3
Common stock [Member]
Class of Stock [Line Items]
Share price (in USD per share)			$ 6.25	$ 26.50
Series C convertible preferred stock [Member]
Class of Stock [Line Items]
Number of warrants exercisable (in shares)		1,975,532
Warrant exercise price (in USD per share)		$ 8.175
IPO [Member] | Common stock [Member]
Class of Stock [Line Items]
Share price (in USD per share)	$ 12
Shares converted (in shares)	9,769,422

Stockholders' Equity (Deficit53

Stockholders' Equity (Deficit) - Narrative (Details) $ / shares in Units, $ in Thousands	Jan. 01, 2017shares	Jul. 14, 2014	Sep. 30, 2016USD ($)$ / sharesshares	May 31, 2015$ / sharesshares	Apr. 30, 2015$ / sharesshares	Aug. 31, 2014$ / sharesshares	Jul. 31, 2014USD ($)$ / sharesshares	May 31, 2015USD ($)$ / shares	Aug. 31, 2014USD ($)$ / shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reverse stock split ratio		0.1223
Stock issuance costs | $			$ 2,400
Proceeds from warrant exercises | $										$ 0	$ 0	$ 8,150
Shares authorized (in shares)							100,000,000			100,000,000	100,000,000
Preferred stock, shares authorized (in shares)							10,000,000			10,000,000	10,000,000
Proceeds from issuance of common stock | $										$ 30,310	$ 75,359	57,807
Shares outstanding (in shares)										25,413,055	20,153,202
Common stock reserved for future issuance (in shares)										4,925,986	3,953,342
Intrinsic value of stock options exercised | $										$ 100	$ 5,000	$ 200
2014 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase in common stock available for issuance (as a percent)							4.00%
Common stock reserved for future issuance (in shares)							1,400,000
Common stock authorized (in shares)										2,926,850
Employee Stock [Member] | 2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase in common stock available for issuance (as a percent)							1.00%
Increase in authorized shares							200,000
Common stock reserved for future issuance (in shares)										503,620	316,322
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)										3,697,643	2,832,467
Unrecognized stock based compensation expense | $										$ 15,600
Weighted average recognition period for stock-based compensation expense										2 years 5 months 4 days
Employee Stock Option [Member] | 2008 and 2014 Equity Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term										4 years
Option expiration period										10 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term										4 years
Award vesting percent										25.00%
Subsequent Event [Member] | 2014 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized shares	1,016,522
Common stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period (in shares)			5,226,369		3,000,000
Share price (in USD per share) | $ / shares			$ 6.25		$ 26.50
Proceeds from issuance of initial public offering | $									$ 57,800
Stock issuance costs | $								$ 5,400
Proceeds from issuance of common stock | $								$ 75,400
IPO [Member] | Common stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period (in shares)							5,000,000
Share price (in USD per share) | $ / shares							$ 12
Stock issuance costs | $									$ 7,100
Shares converted (in shares)							9,769,422
Over-Allotment Option [Member] | Common stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period (in shares)				47,409		410,564
Share price (in USD per share) | $ / shares				$ 26.50		$ 12		$ 26.50	$ 12
Proceeds from issuance of common stock | $			$ 30,300
Common stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period (in shares)							311,923
Convertible preferred Stock, Series C [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of warrants exercised (in shares)							996,940
Warrants Exercised for Cash [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of warrants exercised (in shares)							996,940
Proceeds from warrant exercises | $							$ 8,100
Net Exercised Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of warrants exercised (in shares)							978,592

Stockholders' Equity (Deficit54

Stockholders' Equity (Deficit) - Schedule of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	4,925,986	3,953,342
Stock Options Outstanding [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	3,697,643	2,832,467
Future Stock Grants [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	724,723	804,553
2014 Employee Stock Purchase Plan [Member] | Employee Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	503,620	316,322

Stockholders' Equity (Deficit55

Stockholders' Equity (Deficit) - Schedule of RSU's (Details) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning of period (in shares) | shares	0
Granted (in shares) | shares	118,000
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(10,750)
Outstanding, end of period (in shares) | shares	107,250
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 0
Granted (in dollars per share) | $ / shares	19.39
Vested (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	19.39
Outstanding, end of period (in dollars per share) | $ / shares	$ 19.39

Stockholders' Equity (Deficit56

Stockholders' Equity (Deficit) - Summary of Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, Beginning balance (in shares)	2,832,467	1,907,091
Options granted in period (in shares)	991,110	1,241,394
Options exercised in period (in shares)	(20,782)	(219,290)
Options cancelled in period (in shares)	(182,605)	(96,728)
Options expired in period (in shares)	(29,797)	0
Options outstanding, Ending balance (in shares)	3,590,393	2,832,467	1,907,091
Options vested and expected to vest (in shares)	3,453,099
Exercisable options (in shares)	1,903,268
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, Beginning balance (in USD per share)	$ 11.48	$ 4.16
Weighted average exercise price of options granted in period (in USD per share)	15.49	21.55
Weighted average exercise price of options exercised in period (in USD per share)	3.12	1.38
Weighted average exercise price of options cancelled in period (in USD per share)	19.01	18.61
Weighted average exercise price of options expired in period (in USD per share)	25.65	0
Weighted average exercise price, Ending balance (in USD per share)	12.13	$ 11.48	$ 4.16
Weighted average exercise price of options vested and expected to vest (in USD per share)	12
Weighted average exercise price of exercisable options (in USD per share)	$ 8.86
Weighted average remaining contract term for outstanding options, Beginning	7 years 3 months 29 days	8 years 2 months 26 days
Weighted average remaining contract term for options vested and expected to vest	7 years 3 months 7 days
Weighted average remaining contract term for exercisable options	6 years 1 month 13 days
Aggregate intrinsic value, Beginning balance	$ 5,062	$ 30,447
Aggregate intrinsic value of options vested and expected to vest	5,043
Aggregate intrinsic value of exercisable options	$ 4,493

Stockholders' Equity (Deficit57

Stockholders' Equity (Deficit) - Schedule of Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	$ 9,283	$ 6,297	$ 1,344
Employee [Member] | Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	3,923	2,034	421
Employee [Member] | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	5,029	3,810	703
Non-Employee [Member] | Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	268	205	216
Non-Employee [Member] | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	$ 63	$ 248	$ 4

Stockholders' Equity (Deficit58

Stockholders' Equity (Deficit) - Schedule of Fair Value of Stock Options Granted to Employees (Details) - Employee Stock Option [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average estimated fair value	$ 10.07	$ 15.65	$ 9.32
Risk-free interest rate min	1.10%	1.50%	1.54%
Risk-free interest rate max	2.39%	1.86%	2.16%
Expected stock price volatility min	77.00%	77.00%	90.00%
Expected stock price volatility max	93.00%	91.00%	93.00%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time to maturity	5 years 6 months	5 years 6 months	5 years 6 months
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time to maturity	9 years 5 months 16 days	6 years 29 days	6 years 9 months

Income Taxes Effective Income T

Income Taxes Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory tax rate	35.00%	35.00%
Permanent differences	(1.50%)	(2.10%)
Other	(0.40%)	0.50%
General business credits	2.40%	4.10%
Change in valuation allowance	(35.50%)	(37.50%)
Effective Income Tax Rate Reconciliation, Percent	0.00%	0.00%

Income Taxes Deferred Tax Asset

Income Taxes Deferred Tax Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 52,154	$ 39,965
Research and development credit	5,582	4,290
Depreciation and amortization	2,023	165
Other temporary differences	6,154	2,563
Gross deferred tax assets	65,913	46,983
Deferred tax asset valuation allowance	(65,913)	(46,983)
Net deferred tax assets	$ 0	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Tax Credit Carryforward [Line Items]
Increase in valuation allowance	$ 18.9	$ 14.8
Net operating loss carryforwards	152.5	117.6
Excess tax deductions on option exercises	3.5
Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Research and development tax credit carryforwards	$ 5.6	$ 4.3

Legal Proceedings (Details)

Legal Proceedings (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Oct. 17, 2016
Settled Litigation [Member] | TheraVectys SA v. Immune Design Corp. [Member]
Loss Contingencies [Line Items]
Settlement agreement, escrow deposit		$ 6,000,000
Settlement agreement, additional amount based on future conditions		1,250,000
Settlement agreement, contingent payout based on capital funding		$ 25,000,000
Payment of legal settlement, milestone one, percent		50.00%
Payment of legal settlement, milestone two, percent		50.00%
Estimate of possible loss		$ 7,250,000
Estimated litigation liability		5,850,000
Loss in period	$ 5,850,000
Collaborative Arrangement [Member] | TheraVectys SA [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Obligation		$ 1,400,000

Employee Benefit Plan - Narrati

Employee Benefit Plan - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Contribution Plan Disclosure [Line Items]
Employer contribution	$ 243	$ 214	$ 153
Up to 3% of Employee's Compensation [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer match percentage	100.00%
Percent of employee's salary for employer match	3.00%
Between 3% and 5% of Employee's Compensation [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer match percentage	50.00%
Between 3% and 5% of Employee's Compensation [Member] | Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percent of employee's salary for employer match	3.00%
Between 3% and 5% of Employee's Compensation [Member] | Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percent of employee's salary for employer match	5.00%

Selected Quarterly Financial 64

Selected Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 2,058	$ 8,206	$ 1,133	$ 1,863	$ 1,139	$ 4,653	$ 1,780	$ 1,938	$ 13,260	$ 9,510	$ 6,433
Net loss	$ (14,446)	$ (12,443)	$ (14,347)	$ (12,294)	$ (12,115)	$ (7,407)	$ (10,517)	$ (9,406)	$ (53,530)	$ (39,445)	$ (34,151)
Basic and diluted net loss per share (in dollars per share)	$ (0.57)	$ (0.60)	$ (0.71)	$ (0.61)	$ (0.60)	$ (0.37)	$ (0.54)	$ (0.56)	$ (2.47)	$ (2.06)	$ (4.56)