View Filing Data

Years Ended December 31,

Intrinsic value of options exercised

$1.0 million

$1.1 million

$16.7 million

Fair value of awards vested

$15.0 million

$15.1 million

$9.6 million

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Mar. 02, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	NEWLINK GENETICS CORP
Entity Central Index Key	0001126234
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		37,155,838
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 159,637,289

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 158,708	$ 131,490
Prepaid expenses and other current assets	6,226	5,921
Current income tax receivable	356	5,975
Other receivables	10,176	24,526
Total current assets	175,466	167,912
Non-current assets:
Property and equipment, net	5,091	6,835
Income tax receivable	140	0
Total non-current assets	5,231	6,835
Total assets	180,697	174,747
Current liabilities:
Accounts payable	9,256	22,883
Accrued expenses	12,467	14,309
Current portion of unearned revenue	56	391
Current portion of deferred rent	92	90
Current portion of notes payable and obligations under capital leases	160	232
Total current liabilities	22,031	37,905
Long term liabilities:
Royalty obligation payable to Iowa Economic Development Authority	6,000	6,000
Notes payable and obligations under capital leases	111	285
Deferred rent	998	1,091
Total long-term liabilities	7,109	7,376
Total liabilities	29,140	45,281
Stockholders' Equity:
Blank check preferred stock, $0.01 par value: Authorized shares — 5,000,000 at December 31, 2017 and 2016; issued and outstanding shares — 0 at December 31, 2017 and 2016	0	0
Common stock, $0.01 par value: Authorized shares — 75,000,000 at December 31, 2017 and 2016; issued 37,168,122 and 29,193,718 at December 31, 2017 and 2016 and outstanding 37,109,556 and 29,163,673 at December 31, 2017 and December 31, 2016	372	292
Additional paid-in capital	389,786	295,535
Treasury stock, at cost: 58,566 and 30,045 shares at December 31, 2017 and 2016	(1,142)	(853)
Accumulated deficit	(237,459)	(165,508)
Total stockholders' equity	151,557	129,466
Total liabilities and stockholders' equity	$ 180,697	$ 174,747

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity:
Blank check preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Blank check preferred stock, authorized shares	5,000,000	5,000,000
Blank check preferred stock, issued shares	0	0
Blank check preferred stock, outstanding shares	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares	75,000,000	75,000,000
Common stock, issued shares	37,168,122	29,193,718
Common stock, outstanding shares	37,109,556	29,163,673
Treasury stock, shares	58,566	30,045

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Grant revenue	$ 28,321	$ 32,242	$ 32,358
Licensing and collaboration revenue	390	3,526	36,143
Total operating revenues	28,711	35,768	68,501
Operating expenses:
Research and development	69,866	93,300	71,414
General and administrative	31,726	33,226	30,689
Total operating expenses	101,592	126,526	102,103
Loss from operations	(72,881)	(90,758)	(33,602)
Other income and expense:
Miscellaneous (expense) income	(126)	32	(14)
Interest income	616	237	78
Interest expense	(119)	(22)	(105)
Other income (expense), net	371	247	(41)
Loss before taxes	(72,510)	(90,511)	(33,643)
Income tax benefit (expense)	559	5,356	(6,738)
Net loss	$ (71,951)	$ (85,155)	$ (40,381)
Basic and diluted loss per share (in dollars per share)	$ (2.30)	$ (2.94)	$ (1.41)
Basic and diluted average shares outstanding (in shares)	31,304,309	28,979,327	28,586,585

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	IPO	Common Stock	Common Stock IPO	Additional Paid-in Capital	Additional Paid-in Capital IPO	Treasury Stock	Accumulated Deficit
Balance at beginning of period at Dec. 31, 2014	$ 196,936		$ 280		$ 236,838		$ (222)	$ (39,960)
Balance (shares) at Dec. 31, 2014			27,980,849
Increase (Decrease) in Stockholders' Equity
Share-based compensation	15,940				15,940
Exercise of stock options and vesting of restricted stock awards (in shares)			477,284
Exercise of stock options and vesting of restricted stock awards	3,355		$ 5		3,350
Sale of shares under stock purchase plan (shares)			40,248
Sales of shares under stock purchase plan	851				851
Issuance of common stock (net of offering costs) (in shares)			329,402
Issuance of common stock (net of offering costs)	13,534		$ 3		13,531
Shares withheld for statutory tax withholding (in shares)			(14,183)
Shares withheld for statutory tax withholding	(561)						(561)
Shares issued from treasury (in shares)			542
Shares issued from treasury	0						12	(12)
Tax benefit from employee stock plan awards	6,100				6,100
Net loss	(40,381)							(40,381)
Balance at end of period at Dec. 31, 2015	195,774		$ 288		276,610		(771)	(80,353)
Balance (shares) at Dec. 31, 2015			28,814,142
Increase (Decrease) in Stockholders' Equity
Share-based compensation	16,707				16,707
Exercise of stock options and vesting of restricted stock awards (in shares)			296,933
Exercise of stock options and vesting of restricted stock awards	1,679		$ 4		1,675
Sale of shares under stock purchase plan (shares)			58,609
Sales of shares under stock purchase plan	543				543
Shares withheld for statutory tax withholding (in shares)			(6,011)
Shares withheld for statutory tax withholding	(82)						(82)
Net loss	(85,155)							(85,155)
Balance at end of period at Dec. 31, 2016	$ 129,466		$ 292		295,535		(853)	(165,508)
Balance (shares) at Dec. 31, 2016	29,163,673		29,163,673
Increase (Decrease) in Stockholders' Equity
Share-based compensation	$ 18,508				18,508
Exercise of stock options and vesting of restricted stock awards (in shares)			212,961
Exercise of stock options and vesting of restricted stock awards	962		$ 2		960
Sale of shares under stock purchase plan (shares)			70,787
Sales of shares under stock purchase plan	445		$ 1		444
Issuance of common stock (net of offering costs) (in shares)			1,940,656	5,750,000
Issuance of common stock (net of offering costs)	19,333	$ 55,083	$ 19	$ 58	19,314	$ 55,025
Shares withheld for statutory tax withholding (in shares)			(28,521)
Shares withheld for statutory tax withholding	(289)						(289)
Net loss	(71,951)							(71,951)
Balance at end of period at Dec. 31, 2017	$ 151,557		$ 372		$ 389,786		$ (1,142)	$ (237,459)
Balance (shares) at Dec. 31, 2017	37,109,556		37,109,556

Consolidated Statements of Equity (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Issuance costs of common stock under the ATM Offering	$ 561	$ 0	$ 54
IPO
Issuance costs of common stock under the ATM Offering	$ 3,700

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows From Operating Activities
Net loss	$ (71,951)	$ (85,155)	$ (40,381)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	18,508	16,707	15,940
Depreciation and amortization	1,407	2,084	1,592
Forgiveness of debt	0	(397)	0
Impairment of fixed assets	0	3,958	0
Loss on sale of fixed assets	126	0	0
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(305)	(965)	3,379
State research and development credit receivable	0	0	13
Other receivables	14,350	(19,139)	(1,672)
Accounts payable and accrued expenses	(15,469)	24,770	245
Income taxes (receivable) payable	5,479	(6,834)	9,622
Unearned revenue	(335)	(68)	(12,752)
Deferred rent	(91)	(908)	(73)
Net cash used in operating activities	(48,281)	(65,947)	(24,087)
Cash Flows From Investing Activities
Maturity of certificates of deposit	0	2,180	10,213
Purchase of equipment	(43)	(2,246)	(3,995)
Proceeds on sale of fixed assets	254	0	0
Net cash provided by (used in) investing activities	211	(66)	6,218
Cash Flows From Financing Activities
Issuance of common stock, net of offering costs	74,416	0	13,534
Issuance of common stock under share-based compensation plans	1,407	2,222	4,206
Excess tax benefits from share-based compensation awards	0	0	6,100
Repurchase of common stock	(289)	(82)	(561)
Payments under capital lease obligations and principal payments on notes payable	(246)	(257)	(194)
Net cash provided by financing activities	75,288	1,883	23,085
Net increase (decrease) in cash and cash equivalents	27,218	(64,130)	5,216
Cash and cash equivalents at beginning of year	131,490	195,620	190,404
Cash and cash equivalents at end of year	158,708	131,490	195,620
Supplemental disclosure of cash flows information:
Cash paid for interest	15	22	105
Cash paid for taxes	643	1,022	4,814
Proceeds from income tax refunds	6,651	197	13,796
Noncash financing and investing activities:
Purchased leasehold improvements and equipment in accounts payable and accrued expenses	0	0	398
Assets acquired under capital lease	$ 0	$ 231	$ 0

Description of Business Activities	12 Months Ended
Description of Business Activities	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business Activities	Description of Business Activities NewLink Genetics Corporation (NewLink) was incorporated as a Delaware corporation on June 4, 1999 and initiated operations in April of 2000. NewLink and its subsidiaries (the Company) are devoting substantially all of their efforts toward research and development. The Company has incurred significant losses in all years since being incorporated, except for the year ended December 31, 2014, and has never generated revenue from commercial sales of its drugs. The accompanying financial statements as of and for the year ended December 31, 2017 have been prepared assuming the Company will continue as a going concern. The Company raised net proceeds of $37.6 million from its IPO, completed a follow-on offering of its common stock raising net proceeds of $49.0 million, and raised an additional $58.7 million in net proceeds from an at the market offering prior to March 31, 2015. On November 29, 2016, the Company entered into a sales agreement with Cantor Fitzgerald & Co., under which the Company may sell up to $40.0 million in shares of its common stock in one or more placements at prevailing market prices for its common stock (the ATM Offering). As of December 31, 2017, the Company has raised net proceeds of $19.3 million from the ATM Offering. On October 6, 2017, the Company raised proceeds of $55.2 million, net of offering costs of $3.7 million, from the issuance of 5,750,000 shares of common stock in a public offering. In connection with two license and collaboration agreements the Company entered into during 2014, the Company received a nonrefundable upfront cash payment of $150.0 million from Genentech Inc., a member of the Roche Group, or Genentech, in 2014, and a nonrefundable upfront cash payment of $30.0 million from Merck, Sharpe and Dohme Corp., or Merck, in 2014, as well as an additional milestone payment of $20.0 million from Merck in February 2015. The Company's cash and cash equivalents after these agreements and offerings are expected to be adequate to satisfy the Company's liquidity requirements through 2019. If available liquidity becomes insufficient to meet the Company’s operating obligations as they come due, the Company's plans include pursuing alternative funding arrangements and/or reducing expenditures as necessary to meet the Company’s cash requirements. However, there is no assurance that, if required, the Company will be able to raise additional capital or reduce discretionary spending to provide the required liquidity. Failure by the Company to successfully execute its plans or otherwise address its liquidity needs may have a material adverse effect on its business and financial position, and may materially affect the Company’s ability to continue as a going concern.

Significant Accounting Policies	12 Months Ended
Significant Accounting Policies	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Use of Estimates The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles, or U.S. GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Principles of Consolidation The consolidated financial statements include the financial statements of NewLink and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Cash and Cash Equivalents For the purposes of the consolidated statements of cash flows, the Company considers all highly liquid debt instruments with an original maturity of three months or less to be cash equivalents. Cash and cash equivalents of $158.7 million and $131.5 million at December 31, 2017 and 2016, respectively, consist of checking accounts, money market accounts and treasury bills. Leasehold Improvements and Equipment, and Deferred Rent Leasehold improvements and equipment are capitalized as the Company believes they have alternative future uses and are stated at cost. Equipment under capital leases is stated at the present value of future minimum lease payments. Depreciation on all leasehold improvements and equipment is calculated on the straight-line method over the shorter of the lease term or estimated useful life of the asset. Computer equipment has useful lives of three to five years, lab equipment has a useful life of five years and contract manufacturing organization equipment has a useful life of five years. Deferred rent reflects improvement allowances from the Company's lessors deferred to be recognized as part of lease expense over the remaining term of the lease, which is recognized on a straight-line basis. Total deferred rents were $1.1 million and $1.2 million as of December 31, 2017 and 2016, respectively. Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset group to future net undiscounted cash flows expected to be generated by the asset group, primarily relating to proceeds for selling the assets. If such assets are considered to be impaired, the impairment to be recognized is measured at the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or fair value less costs to sell. Revenue Recognition The Company recognizes revenue for the performance of services or the shipment of products when each of the following four criteria is met: (1) persuasive evidence of an arrangement exists; (2) products are delivered or as services are rendered; (3) the sales price is fixed or determinable; and (4) collectability is reasonably assured. The Company receives payments from government entities under its grants and contracts with the National Institute of Health, the Department of Defense, and the United States Department of Health and Human Services. These agreements provide the Company cost reimbursement plus a percentage for certain types of expenditures in return for research and development activities over a contractually defined period. Grant revenues are recognized in the period during which the related costs are incurred, provided that the conditions under which the costs submitted or to be submitted for reimbursement have been met and the Company has only perfunctory obligations outstanding. During the years ended December 31, 2017, 2016, and 2015, the Company has earned $28.3 million, $32.2 million, and $32.4 million in grant revenue, respectively. The Company had $9.3 million and $23.9 million of receivables from the government contracts recorded in other receivables and $465,000 and $4.3 million of unbilled expenses relating to the government contracts recorded in prepaid expenses and other assets on the balance sheet as of December 31, 2017 and 2016, respectively. The Company had $1.8 million and $2.9 million of accrued expenses for subcontractor fees and $4.9 million and $19.3 million of subcontractor fees in accounts payable for amounts incurred under the government contracts as of December 31, 2017 and 2016, respectively. The Company follows ASC 605-25, Revenue Recognition - Multiple-Element Arrangements and ASC 808, Collaborative Arrangements , if applicable, to determine the recognition of revenue under our license and collaborative research, development and commercialization agreements. The terms of these agreements generally contain multiple elements, or deliverables, which may include (1) licenses to our intellectual property, (2) materials and technology, (3) clinical supply, and/or (4) participation on joint research or joint steering committees. The payments the Company may receive under these arrangements typically include one or more of the following: non-refundable, up-front license fees; funding of research and/or development efforts; amounts due upon the achievement of specified milestones; and/or royalties on future product sales. ASC 605-25 provides guidance relating to the separability of deliverables included in an arrangement into different units of accounting and the allocation of arrangement consideration to the units of accounting. The evaluation of multiple-element arrangements requires management to make judgments about (1) the identification of deliverables, (2) whether such deliverables are separable from the other aspects of the contractual relationship, (3) the estimated selling price of each deliverable, and (4) the expected period of performance for each deliverable. To determine the units of accounting under a multiple-element arrangement, management evaluates certain separation criteria, including whether the deliverables have stand-alone value, based on the relevant facts and circumstances for each arrangement. Management then estimates the selling price for each unit of accounting and allocates the arrangement consideration to each unit utilizing the relative selling price method. The allocated consideration for each unit of accounting is recognized over the related obligation period in accordance with the applicable revenue recognition criteria. If there are deliverables in an arrangement that are not separable from other aspects of the contractual relationship, they are treated as a combined unit of accounting, with the allocated revenue for the combined unit recognized in a manner consistent with the revenue recognition applicable to the final deliverable in the combined unit. Payments received prior to satisfying the relevant revenue recognition criteria are recorded as unearned revenue in the accompanying balance sheets and recognized as revenue when the related revenue recognition criteria are met. The Company typically receives non-refundable, up-front payments when licensing our intellectual property, which often occurs in conjunction with a research and development agreement. If management believes that the license to our intellectual property has stand-alone value, the Company generally recognizes revenue attributed to the license upon delivery provided that there are no future performance requirements for use of the license. When management believes that the license to our intellectual property does not have stand-alone value, the Company would recognize revenue attributed to the license on a straight-line basis over the contractual or estimated performance period. When the performance period is not specifically identifiable from the agreement, the Company would estimate the performance period based upon provisions contained within the agreement, such as the duration of the research or development term. For payments payable on achievement of milestones that do not meet all of the conditions to be considered substantive, the Company recognizes a portion of the payment as revenue when the specific milestone is achieved, and the contingency is removed. Other contingent event-based payments for which payment is either contingent solely upon the passage of time or the result of collaborator's performance are recognized when earned. Expenses Accrued Under Contractual Arrangements with Third Parties; Accrued Clinical Expenses The Company estimates its accrued expenses through a process of reviewing open contracts and purchase orders, communicating with personnel to identify services that have been performed and estimating the level of service performed and the associated cost incurred for the service that may not be invoiced from the provider. The estimates of accrued expenses as of each balance sheet date are based on facts and circumstances known at that time. Such estimates are periodically confirmed with the service providers to verify accuracy. The Company bases its expenses related to clinical trials on estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and contract research organizations that conduct and manage clinical trials on behalf of the Company. Invoicing from third-party contractors for services performed can lag several months. The Company accrues the costs of services rendered in connection with third-party contractor activities based on its estimate of management fees, site management and monitoring costs and data management costs as contracted. Differences between actual clinical trial costs and estimated clinical trial costs are adjusted for in the period in which they become known through operations. Research and Development Research and development costs are expensed as incurred. Research and development expenses consist primarily of employee-related expenses, which include salaries, bonuses, benefits and share-based compensation; manufacturing-related costs; clinical trial expenses which include expenses incurred under agreements with contract research organizations, investigative sites and consultants that conduct our clinical trials; facilities, depreciation of fixed assets and other allocated expenses, which include direct and allocated expenses for rent and maintenance of research facilities and equipment; license fees for and milestone payments related to in-licensed products and technology; and costs associated with non-clinical activities and regulatory approvals. Patents The Company generally applies for patent protection on processes and products. Patent application costs are expensed as incurred as a component of general and administrative expense, as recoverability of such expenditures is uncertain. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using 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 operating results in the period that includes the enactment date. Management assesses the realizability of deferred tax assets and records a valuation allowance if it is more likely than not that all or a portion of the deferred tax assets will not be realized. The Company accounts for the effect of any uncertain tax positions based on a more likely than not threshold to the recognition of the tax positions being sustained based on the technical merits of the position under scrutiny by the applicable taxing authority. If a tax position or positions are deemed to result in uncertainties of those positions, the unrecognized tax position is estimated based on a cumulative probability assessment that aggregates the estimated tax liability for all uncertain tax positions. Interest and penalties assessed, if any, are recorded in its consolidated statement of operations in interest expense and other expenses. As of December 31, 2017 and 2016, the Company had a recognized uncertain tax position of $653,000. Share-Based Compensation The Company is required to estimate the grant-date fair value of share-based payment transactions with employees which include stock options, restricted stock units (RSUs) and performance shares (PSUs) and recognizes the compensation cost over the requisite service period based on the estimated fair values as well as expected forfeiture rates. The Company estimates the fair value of each award granted using the Black-Scholes option pricing model. The Black-Scholes model requires the input of assumptions, including the expected stock price volatility, the calculation of expected term and the fair value of the underlying common stock on the date of grant, among other inputs. The Company calculates the fair value of the award on the grant date, which is the date the award is authorized by the Board of Directors or Chief Executive Officer and the employee has an understanding of the terms of the award. Generally, the Company has issued employee awards that vest either monthly or 25% vest on the first anniversary date of issuance with the remaining options vesting ratably over the next 36 months. The Company records compensation cost on a straight-line basis over the vesting period. The fair value of RSUs that are subject to cliff vesting are recognized as compensation expense over the requisite service period using the straight line attribution method, and the fair value of RSUs that are subject to graded vesting are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of PSUs are recognized as compensation expense beginning at the time in which the performance conditions are deemed probable of achievement, over the remaining requisite service period. The Company has issued awards to nonemployee consultants and advisers. All grants to nonemployees are valued using the same fair value method that we use for grants to employees. The compensation cost on these awards is measured each period until vesting, and is recognized through the earlier of the vesting of the award or completion of services by the nonemployee. Following is a description of the inputs for the Black-Scholes model: Exercise Price The Company uses the quoted market price as listed on the public exchange on the date of grant. If Incentive Stock Options are granted to a 10% stockholder in the Company, the exercise price shall not be less than 110% of the common stock’s fair market value on the date of grant. Expected Term (in Years) The expected term of a stock option is the period of time for which the option is expected to be outstanding. The Company uses historical exercise and option expiration data to estimate the expected term for the Black-Scholes grant-date valuation. Risk-Free Interest Rate The Company uses the average yield on current U.S. Treasury instruments with terms that approximate the expected term of the stock options being valued. Expected Dividend Yield The expected dividend yield for all of the Company’s stock option grants is 0%, as the Company has not declared a cash dividend since inception and has no plans to declare a dividend. Expected Volatility The Company uses its historical stock price volatility. The volatility is calculated over a period of time commensurate with the expected term for the options granted. Forfeitures The share-based compensation expense has been reduced for estimated forfeitures. The estimated forfeiture rate is based on historical experience of the Company’s option plan, which the Company expects to continue at the current level, and any adjustments in the forfeiture rate in the future will result in a cumulative adjustment in the period that this estimate is changed. Ultimately, the total compensation expense recognized for any given stock-based award over its vesting period will only be for those shares that actually vest. Segments The Company operates in one segment. The Company conducts research and development activities based from facilities located in Ames, Iowa and has corporate headquarters in Ames, Iowa and Austin, Texas. The Company conducts preclinical and clinical research in the biopharmaceutical industry. The chief operating decision maker uses cash flow as the primary measure to manage the business and management does not segment its business for internal reporting or decision-making. Financial Instruments and Concentrations of Credit Risk The fair values of cash and cash equivalents, receivables and accounts payable, which are recorded at cost, approximate fair value based on the short-term nature of these financial instruments. The fair value of notes payable and capital lease obligations was $271,000 and $517,000 as of December 31, 2017 and 2016, respectively, and was determined using Level 2 inputs (computed in accordance with ASC 820). The Company is unable to estimate the fair value of the royalty obligation based on future product sales as the timing of payments, if any, is uncertain. Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. Cash and cash equivalents are held by financial institutions and are federally insured up to certain limits. At times, the Company’s cash and cash equivalents balance exceeds the federally insured limits. To limit the credit risk, the Company invests its excess cash primarily in high quality securities such as money market funds. Earnings per share (EPS) The Company computes basic EPS attributable to the Company's common stockholders by dividing net income (loss) attributable to the Company by our weighted-average common shares outstanding during the period. Diluted EPS reflects the potential dilution beyond shares for basic EPS that could occur if securities or other contracts to issue common stock were exercised, converted into common stock, or resulted in the issuance of common stock that would have shared in our earnings. The Company computes basic and diluted EPS using net income (loss) attributable to the Company's common stockholders, and its actual weighted-average shares. Concentration of Revenue Genentech, a member of the Roche Group, and Merck Sharpe and Dohme Corp., or Merck, accounted for 1.2% and 0.2%, respectively, of the $28.7 million of revenue for the year ended December 31, 2017, with the remainder obtained from government grants. Genentech and Merck accounted for 7.6% and 2.3%, respectively, of the $35.8 million of revenue earned for the year ended December 31, 2016, with the remainder obtained from government grants. Genentech and Merck accounted for 21.5% and 31.3%, respectively, of the $68.5 million of revenue earned for the year ended December 31, 2015, with the remainder obtained from government grants. Recent Accounting Pronouncements On May 28, 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The new standard is effective for the Company on January 1, 2018. The standard permits the use of either the retrospective or cumulative effect transition method. The Company will adopt the standard on a modified retrospective basis at January 1, 2018, with an adjustment for the cumulative effect of all changes recognized in beginning retained earnings. The Company has completed its analysis of the adoption impact and will record an immaterial entry to beginning retained earnings. In February 2016, the Financial Accounting Standards Board, or the FASB, issued ASU No. 2016-02, Leases, to improve financial reporting for leasing transactions. The new standard requires lessees to recognize on the balance sheet a right of use asset and related lease liability for all leases with terms greater than twelve months. The ASU also requires disclosures about the amount, timing, and uncertainty of cash flows arising from leases. The effective date for public entities is fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted for all entities. The Company does not currently have any material leases and therefore does not anticipate adoption to have a material impact on its consolidated financial statements and related disclosures.

Leases

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Leases

(a) Capital Leases

The following is an analysis of the leased property under capital leases by major class (in thousands):



	Asset Balances at December 31,
Class of property	2017			2016
Lab equipment	$	720		$	720
Leasehold improvements	27			27
Computer equipment	54			54
Total property under capital leases	801			801
Less accumulated depreciation and amortization	(652		)	(586		)
Capital leased assets, net	$	149		$	215

The depreciation and amortization reflected above has been recorded in both research and development and general administrative expense in the consolidated statements of operations.

The following is a schedule of the future minimum lease payments under capital leases together with the present value of the net minimum lease payments as of December 31, 2017 (in thousands):



Year Ending December 31:
2018	$	74
Less amount representing interest	(1		)
Present value of net minimum lease payments	$	73

(b) Operating Leases

The Company has certain facility leases with terms ranging between one and five years. Lease expense is recognized on a straight-line basis. Rental expense for operating leases during the years ended December 31, 2017, 2016 and 2015, was $1.2 million, $1.7 million, and $1.7 million, respectively, including those with terms less than one year, and has been included in both research and development and general and administration in the consolidated statements of operations.

Future minimum lease payments under the noncancelable operating leases (with initial or remaining lease terms in excess of one year) as of December 31, 2017 are as follows (in thousands):



Year Ending December 31:
2018	$	1,157
2019	1,104
2020	1,008
Thereafter	9,391
Total	$	12,660

Leasehold improvements and equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Leasehold improvements and equipment

Leasehold improvements and equipment at December 31, 2017 and 2016 consisted of the following:



	Year Ended December 31,
	2017			2016
Leasehold improvements	$	5,310		$	5,310
Computer and office equipment	2,326			2,219
Lab and leased equipment	3,979			4,056
Contract manufacturing organization equipment	114			486
Assets not placed in service	—			490
Total leasehold improvements and equipment	11,729			12,561
Less accumulated depreciation and amortization	(6,638		)	(5,726		)
Total leasehold improvements and equipment, net	$	5,091		$	6,835

Long-Term Debt Conversion to Royalty Obligation	12 Months Ended
Long-Term Debt Conversion to Royalty Obligation	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt and Conversion to Royalty Obligation	Long-Term Debt and Conversion to Royalty Obligation March 2005 Iowa Department of Economic Development Loan In March 2005, the Company entered into a $6.0 million forgivable loan agreement with the Iowa Department of Economic Development, or the IDED. Under the agreement, in the absence of default, there were no principal or interest payments due until the completion date for the project. The balance outstanding under the loan agreement was $6.0 million as of December 31, 2011. This loan was converted into a royalty obligation under the terms of a settlement agreement entered into on March 26, 2012, or the IEDA Agreement, with the Iowa Economic Development Authority (the IEDA), as successor in interest to the IDED. March 2012 IEDA Royalty Obligation Under the terms of the IEDA Agreement the Company agreed to pay a 0.5% royalty on future product sales up to a cap of $6.8 million in exchange for IDED’s release of the Company's job creation and project expenditure obligations and their release of the security interest in substantially all of the Company's assets. As no payments are expected in the next 12 months, the entire accrued royalty obligation of $6.0 million is considered long-term as of December 31, 2017. 2009 and 2012 Iowa State University Research Park Notes In 2009, the Company executed a promissory note in favor of Iowa State University Research Park, or ISURP, in an original principal amount of $800,000, which is due in monthly installments through March, 2018. The note represents amounts owed by the Company to ISURP for certain improvements that were made to facilities the Company leases from ISURP. The principal and interest owed under the note is amortized over an eight-year period. Interest is payable monthly under this promissory note, initially at a rate of 3.0% per annum and increasing to 5.0% per annum after five years from the date the improvements were completed. ISURP may accelerate all amounts owed under the note upon an event of default, including the Company’s uncured material breach of the terms of the note or the lease or upon early termination of the lease. In the event of a default under the note, amounts owed under the note will bear interest at 8.0% per annum. The balance outstanding under the 2009 note was $29,000 and $140,000 at December 31, 2017 and December 31, 2016, respectively. In 2012, the Company executed a promissory note in favor of ISURP in an original principal amount of $456,000, which is due in monthly installments through September 2020. The note represents amounts owed by the Company to ISURP for certain additional improvements that were made to facilities the Company leases from ISURP. The principal and interest owed under the note is amortized over an eight-year period. Interest is payable monthly under this promissory note, initially at a rate of 3.0% per annum and increasing to 5.0% per annum after five years from the date the improvements were completed. ISURP may accelerate all amounts owed under the note upon an event of default, including the Company’s uncured material breach of the terms of the note or the lease or upon early termination of the lease. In the event of a default under the note, amounts owed under the note will bear interest at 8.0% per annum. The balance outstanding under the 2012 note was $169,000 and $227,000 at December 31, 2017 and December 31, 2016, respectively. March 2010 City of Ames Forgivable Loan In March 2010, the Company entered into a $400,000 forgivable loan agreement with the City of Ames, Iowa and the Ames Chamber of Commerce, jointly, as lenders. The project provided the Company with financial assistance to construct new facilities within the Ames city limits. In the absence of a default, there were no principal or interest payments due until March 10, 2016. The project called for the Company to create or retain at least 150 full-time positions located in Ames, Iowa by March 10, 2016. The agreement required the Company to enter into a five-year building lease with the option for extension for an additional five years of not less than 20,000 square feet within the corporate limits of the City of Ames by March 10, 2015, which requirement the Company met by the March 10, 2015 deadline. As of March 10, 2016, the Company had satisfactorily fulfilled all of the above terms of the loan agreement and the loan was forgiven. Accordingly, the entire amount of $397,000 was derecognized with a corresponding amount recorded in grant revenue for the year ended December 31, 2016.

License and Research Collaboration Agreements	12 Months Ended
License and Research Collaboration Agreements	Dec. 31, 2017
Revenue Recognition [Abstract]
License and Research Collaboration Agreements	License and Research Collaboration Agreements Genentech, a Member of the Roche Group In October 2014, the Company entered into a worldwide exclusive collaboration and license agreements with Genentech for the development and commercialization of NLG919, one of NewLink's clinical stage IDO pathway inhibitors and for a research collaboration for the discovery of next generation IDO/TDO compounds to be developed and commercialized under this agreement. Under the terms of the agreement, the Company received a nonrefundable upfront cash payment of $150.0 million from Genentech in 2014. On June 6, 2017, we received a formal notice of Genentech’s intent to terminate the Genentech Agreement with respect to NLG919. As part of the partial termination, worldwide rights to NLG919 reverted to us, and Genentech granted to us an exclusive, royalty-bearing license under certain Genentech intellectual property to develop and commercialize NLG919. If NLG919 is commercialized, we will be obligated to pay to Genentech royalties as a low single-digit percentage of net sales of NLG919. The Genentech Agreement continues with regards to any next generation products as defined under the Genentech Agreement and the Company is eligible to receive milestone payments of up to $561.0 million upon achieving certain development, regulatory, and sales-based milestones with respect to next generation IDO/TDO products. The Company retains the right to exercise an option to co-promote any next generation IDO/TDO products with Genentech for the U.S. market and is also eligible to receive escalating royalty payments on potential commercial sales of next generation IDO/TDO products by Genentech. The Company was obligated to deliver multiple non-contingent deliverables related to the NLG919 upfront cash payment. These deliverables include the NLG919 development and commercialization license, research license, program materials and technology, clinical supply of NLG919 product, manufacturing technology, participation in a joint research committee, or JRC, and providing an alliance manager. The Company's obligations under the JRC ended November 2016. The NLG919 development and commercialization license and research license are separate deliverables, but without the ability to develop NLG919, the ability to perform research on the compound would not benefit Genentech. Therefore, the Company believes that the value of the development and commercialization license cannot be separated from the research license value and the two are valued together. The other deliverables qualify as separate units of accounting. The respective standalone value from each of these deliverables has been determined by applying the best estimated selling price method and the revenue was allocated based on the relative selling price method with revenue recognition timing to be determined either by delivery or the provision of service. The estimated selling price determination required the use of significant estimates. To determine the stand-alone value of the license, we considered the negotiation discussions that led to the final terms of the agreement. The Company utilized historical cost plus an estimated gross margin to estimate the selling price for program materials and technology, manufacturing technology, clinical supply, participation in a JRC, and participation of an alliance manager. The program materials and technology, clinical supply of NLG919, participation in a JRC and participation of an alliance manager were delivered throughout the duration of the agreement. The license and manufacturing technology was delivered shortly after the effective date of the agreement. The Company recognized revenue under this agreement of $335,000 for the year ended December 31, 2017. This amount includes the recognition of $335,000 for providing an alliance manager to the collaboration. Revenues of $56,000 remain deferred as of December 31, 2017 for the deliverable of providing an alliance manager through the first part of 2018. All other deliverables identified within the collaboration and license agreement have been completed in their entirety. The Company recognized revenue under this agreement of $2.7 million for the year ended December 31, 2016. This amount includes the recognition of $180,000 for participation in the JRC and $670,000 for providing an alliance manager to the collaboration. Additionally, $1.9 million was recognized for amounts received as reimbursement for the Company's employees working on the project. Revenues of $391,000 remain deferred as of December 31, 2016 for deliverables identified within the collaboration and license agreement that have not yet been completed in their entirety. The Company recognized revenue under this agreement of $14.7 million for the year ended December 31, 2015. This amounts includes the recognition of $9.4 million for program materials and technology transfer, $2.5 million for the clinical supply of NLG919 product, $151,000 for participation in the JRC, and $502,000 for providing an alliance manager to the collaboration. Additionally, $2.1 million was recognized for amounts received as reimbursement for the Company's employees working on the project. Revenues of $1.2 million remain deferred as of December 31, 2015 for deliverables identified within the collaboration and license agreement that have not yet been completed in their entirety. The Company is eligible to receive from Genentech tiered royalty payments based on product sales, with royalty rates varying based on the territory of the sales, the product, the licenses incorporated in the development, and the opt-in by the Company during development. Royalties will be accounted for as contingent revenue and will be recognized as earned in accordance with contract terms, when Genentech results are reported, the amount can be reasonably estimated, and collectability is reasonably assured. Merck Sharpe & Dohme Corp. In November 2014, the Company entered into a licensing and collaboration agreement with Merck to develop, manufacture and commercialize rVSV∆G-ZEBOV GP, an Ebola vaccine the Company licensed from the Public Health Agency of Canada, or PHAC. Under the terms of the agreement, the Company granted Merck an exclusive, royalty-bearing license to the rVSV∆G-ZEBOV GP and related technology. NewLink received a $30.0 million non-refundable, upfront payment in December 2014, and was also eligible for a one-time $20.0 million non-refundable milestone payment upon the initiation of the pivotal clinical trial using the current rVSV∆G-ZEBOV GP vaccine product as one arm of the trial. In February 2015, this milestone was achieved and the Company received the milestone payment. On December 5, 2017, the Merck Agreement was amended in connection with our entry into an Amended and Restated PHAC license on December 5, 2017 NewLink can receive escalating royalties on potential commercial sales by Merck of the current product candidate ranging from single-digit to double-digits on the rVSV∆G-ZEBOV GP license agreement product sales on increasing levels of annual net sales worldwide. Merck will lead the development of rVSV∆G-ZEBOV GP in order to create a marketable product safe for human use. The Company completed all deliverables under the Merck Agreement in their entirety during the year ended December 31, 2016. The Company recognized revenue under this agreement of $815,300 for the year ended December 31, 2016. This amount includes the recognition of $53,800 relating to the remaining deliverables and $761,500 for the reimbursement of costs associated with the Ebola clinical trials not reimbursed under the Company's government contracts. No revenue remains deferred as of December 31, 2016. The Company recognized revenue under this agreement of $21.4 million for the year ended December 31, 2015. This amount includes the recognition of the $20.0 million milestone payment from Merck after notification from Merck that the milestone event specified in the license and collaboration agreement between the two companies relating to the further development of the rVSV-EBOV vaccine product candidate had been achieved. The milestone pertains to the initiation of a key clinical trial for the vaccine. The Company recognized $170,000 in revenue relating to the other deliverables and $1.2 million for the reimbursement of costs associated with Ebola clinical trials not reimbursed under the Company's government contracts. Revenue of $53,800 was deferred as of December 31, 2015. The Company is eligible to receive from Merck tiered royalty payments based on product sales, with royalty rates varying based on Merck sales of the current rVSV∆G-ZEBOV GP vaccine product and Merck sales of other products included within the Company’s patent rights. Royalties will be recognized as earned in accordance with contract terms, when Merck results are reported, the amount can be reasonably estimated, and collectability is reasonably assured.

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders' Equity Common Stock The holders of common stock are entitled to one vote per share on all matters to be voted upon by the Company stockholders. Subject to preferences applicable to outstanding preferred stock, the holders of common stock are entitled to receive ratably such dividends, if any, as may be declared from time to time by the Company's Board of Directors. In the event of liquidation, dissolution, or winding up of the Company, the holders of common stock are entitled to share ratably in all assets remaining after payment of liabilities subject to prior distribution rights of the preferred stock. Preferred Stock As of December 31, 2017 and 2016, the Company had no outstanding preferred stock. The Company's Board of Directors has the authority to issue up to 5,000,000 shares of preferred stock in one or more series and to fix the voting power and such designations, preferences, and rights of such series, subject to approval of outstanding preferred series shareholders.

Common Stock Equity Incentive Plans

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Common Stock Equity Incentive Plan

Common Stock Equity Incentive Plans

In April 2000, the stockholders approved NewLink’s 2000 Equity Incentive Plan. as amended, or the 2000 Plan, and in July 2009, the stockholders approved NewLink’s 2009 Equity Incentive Plan, as amended, or the 2009 Plan. Following the approval of the 2009 Plan, all options outstanding under the 2000 Plan were effectively included under the 2009 Plan. Under the provisions of the 2009 Plan, NewLink may grant the following types of common stock awards:


•	Incentive Stock Options


•	Nonstatutory Stock Options


•	Restricted Stock Awards


•	Stock Appreciation Rights

Awards under the 2009 Plan, as amended, may be made to officers, employees, members of the NewLink Board of Directors, advisors, and consultants to NewLink. As of December 31, 2017 there were 10,238,220 shares of common stock authorized for the 2009 Plan and 1,195,358 shares remained available for issuance. As of December 31, 2016 there were 9,071,674 shares of common stock authorized for issuance pursuant to the 2009 Plan and 1,044,717 shares remained available for issuance.

The following table summarizes the authorized increases of common stock under the 2009 Plan:



Date Authorized		Authorized Shares Added
May 15, 2010		1,238,095
January 7, 2011		714,286
January 1, 2013		838,375
January 1, 2014		1,066,340
January 1, 2015		1,119,255
January 1, 2016		1,152,565
January 1, 2017		1,166,546

Subsequent to year end, on January 1, 2018, an additional 1,484,382 shares of common stock were added to the shares reserved for future issuance under the 2009 plan. The increases in the authorized shares of common stock under the 2009 Plan in 2010 and 2011 were approved by the Company’s stockholders. The increases in the authorized shares of common stock under the 2009 Plan in 2012 through 2017 were made pursuant to an “evergreen provision,” in accordance with which, on January 1 of each year, from 2012 to (and including) 2019, a number of shares of common stock in an amount equal to 4% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or such lesser amount of shares (or no shares) approved by the Company's Board of Directors, was added or will be added to the shares reserved under the 2009 Plan.

Under the terms of the Company's 2010 Non-Employee Directors’ Stock Option Plan, as amended, or the Directors’ Plan, which became effective on November 10, 2011, 238,095 shares of common stock were reserved for future issuance. On May 9, 2013, an additional 161,905 shares of common stock were added to the reserve. As of December 31, 2017, zero shares remained available for issuance under the Directors' Plan.

Under the terms of the Company's 2010 Employee Stock Purchase Plan, as amended, or the 2010 Purchase Plan, which became effective on November 10, 2011, 214,285 shares of common stock were reserved for future issuance. On May 9, 2013, an additional 185,715 shares of common stock were added to the reserve. As of December 31, 2017, 101,996 shares remained available for issuance under the plan. During the years ended December 31, 2017 and 2016, 70,787 and 58,609 shares of common stock, respectively, were purchased under the terms of the 2010 Purchase Plan.

Share-based Compensation

Share-based employee compensation expense for the years ended December 31, 2017, 2016 and 2015, was $18.5 million, $16.7 million, and $15.9 million, respectively, and is allocated between research and development and general and administrative expenses within the consolidated statements of operations. As of December 31, 2017, the total compensation cost related to unvested option awards not yet recognized was $18.0 million and the weighted average period over which it is expected to be recognized was 2 years. The total income tax benefit recognized in the consolidated statements of operations for stock-based compensation arrangements was $16.6 million, $13.7 million and $7.8 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Stock Options

The Company's Board of Directors determines the vesting period for each stock option award. Generally, stock options awarded to date under the 2009 Plan vest monthly or vest 25% on the first anniversary date of issuance with the remaining options vesting ratably over the next 36 months, though some options have effective vesting periods that begin prior to the date of grant. In such cases, compensation expense was recognized for the vested portion of the award upon grant. The stock options may include provisions for early exercise of options. If any shares acquired are unvested, they are subject to repurchase at the Company’s discretion until they become vested.

The following table summarizes the stock option activity for the year ended December 31, 2017:



	Number of options		Weighted average exercise price		Weighted average remaining contractual term (years)
Outstanding at beginning of period	6,278,542		$	14.93
Options granted	1,526,787		11.61
Options exercised	(120,716	)	7.96
Options forfeited	(324,947	)	19.88
Options expired	(157,445	)	33.27
Outstanding at end of period	7,202,221		13.72		5.3
Options exercisable at end of period	5,489,349		$	12.51	4.3

Based on the December 31, 2017 price of $8.11 per share, the intrinsic value of stock options outstanding at December 31, 2017, was $11.6 million, of which $11.6 million and $6,000 related to stock options that were vested and unvested, respectively, at that date.

The following table summarizes options that were granted during the years ended December 31, 2017, 2016 and 2015, and the range of assumptions used to estimate the fair value of those stock options using a Black-Scholes valuation model:



	Years Ended December 31,
	2017	2016	2015
Number of options granted	1,526,787	1,346,758	1,019,445
Risk-free interest rate	1.91%-2.22%	1.19%-1.97%	1.51%-2.00%
Expected dividend yield	—	—	—
Expected volatility	68.9%-76.88%	67.1%-69.8%	62.5%-67.3%
Expected term (in years)	1.2-7.8	5.9-7.4	5.9-7.0
Weighted average grant-date fair value per share	$7.72	$11.91	$26.36

The following table summarizes the intrinsic value of options exercised and the fair value of awards vested during the years ended December 31, 2017, 2016 and 2015:

The fair value of options vested for the year ended December 31, 2015, includes the accelerated vesting as a result of an employee's departure from the Company of $2.8 million.

Restricted Stock

Restricted stock is common stock that is subject to restrictions, including risks of forfeiture, determined by the plan committee of the Board of Directors in its sole discretion, for so long as such common stock remains subject to any such restrictions. A holder of restricted stock has all rights of a stockholder with respect to such stock, including the right to vote and to receive dividends thereon, except as otherwise provided in the award agreement relating to such award. Restricted stock awards are equity classified within the consolidated balance sheets. The fair value of each restricted stock grant is estimated on the date of grant using the closing price of the Company's Common Stock on The NASDAQ Global Market on the date of grant.

During the year ended December 31, 2017 and 2016, there were 0 and 193,834 shares of restricted stock granted, respectively. Compensation expense is determined for the issuance of restricted stock by amortizing using either a straight-line basis or the accelerated attribution method over the requisite service period, or the vesting period, the aggregate fair value of the restricted stock awarded based on the closing price of the Company's common stock on the date of grant.

A summary of the Company's unvested restricted stock at December 31, 2017 and changes during the year ended December 31, 2017 is as follows:



	Restricted Stock		Weighted Average Grant Date Fair Value
Unvested at beginning of period	288,964		$	34.94
Granted	—		—
Vested	(92,245	)	33.70
Forfeited/cancelled	(28,498	)	33.72
Unvested at end of period	168,221		$	35.82

As of December 31, 2017, the total remaining unrecognized compensation cost related to issuances of restricted stock was approximately $3.7 million and is expected to be recognized over a weighted-average period of 1.6 years. The fair value of restricted stock awards vested during the year ended December 31, 2017 was $932,000.

The Company does not have a formal policy regarding the source of shares issued upon exercise of stock options or issuance of restricted stock. The Company expects shares issued to be issued from treasury shares or new shares.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

U.S. Tax Reform

On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the "Tax Act"). The Tax Act makes broad and complex changes to the U.S. tax code that affect fiscal 2017. The Tax Act also makes a number of changes to U.S. federal income tax laws that will affect 2018 and later years, including, but not limited to, a reduction of the U.S. federal corporate income tax rate from 35% to 21%, the repeal of the corporate alternative minimum tax ("AMT"), the limitation on net operating loss deductions to 80 percent of taxable income for losses beginning after December 31, 2017 and the repeal of the current two-year carryback provision for net operating losses arising after 2017.

In connection with its analysis of the impact of the Tax Act, the Company has recorded a net tax benefit of $140,000 in 2017 which is for the release of the valuation allowance that had previously been recorded to offset the AMT deferred income tax benefit and classified this amount as a noncurrent income tax receivable. The Tax Act provides that AMT credit carryovers are partially refundable beginning in 2018 as an offset to a tax liability. The Company expects the amount to be fully refunded by 2021. The Tax Act had no other material impacts to the consolidated financial statements upon enactment.

Income tax benefit (expense) consists of (in thousands):



	Current			Deferred		Total
Year Ended December 31, 2017:
U.S. federal	$	332		$	140	$	472
State and local	87			—		87
	$	419		$	140	$	559

Year Ended December 31, 2016:
U.S. federal	$	6,469		$	—	$	6,469
State and local	(1,113		)	—		(1,113		)
	$	5,356		$	—	$	5,356

Year Ended December 31, 2015:
U.S. federal	$	(5,522	)	$	—	$	(5,522	)
State and local	(1,216		)	—		(1,216		)
	$	(6,738	)	$	—	$	(6,738	)

The tax effects of temporary differences that give rise to significant portions of deferred tax assets and the deferred tax liability at December 31, 2017 and 2016 are presented below (in thousands):



	Year Ended December 31,
	2017			2016
Deferred tax assets:
Net operating loss carryforwards	$	10,622		$	654
Federal research and development tax credits	26,327			20,836
Share-based compensation	11,780			11,843
Deferred rent	327			491
Minimum tax credits	—			143
Accrued compensation	789			427
Unearned revenue	17			163
Charitable contributions	39			13
Leasehold improvements and equipment	297			552
Gross deferred tax assets	50,198			35,122
Less valuation allowance	(50,198		)	(35,122		)
Total deferred tax assets	—			—

The valuation allowance for deferred tax assets as of December 31, 2017 and 2016 was $50.2 million and $35.1 million, respectively. The net change in the total valuation allowance for the years ended December 31, 2017 and 2016 was an increase of $15.1 million and of $14.4 million, respectively. In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected taxable income, and tax planning strategies in making this assessment. Valuation allowances have been established for the entire amount of the net deferred tax assets as of December 31, 2017 and 2016, due to the uncertainty of future recoverability.

Federal operating loss carryforwards as of December 31, 2017 of approximately $38.8 million and federal research credit carryforwards of approximately $26.2 million expire at various dates from 2026 through 2035. Sections 382 and 383 of the Internal Revenue Code limit a corporation’s ability to utilize its net operating loss carryforwards and certain other tax attributes (including research credits) to offset any future taxable income or tax if the corporation experiences a cumulative ownership change of more than 50% over any rolling three year period. State net operating loss carryforwards (and certain other tax attributes) may be similarly limited. An ownership change can therefore result in significantly greater tax liabilities than a corporation would incur in the absence of such a change and any increased liabilities could adversely affect the corporation’s business, results of operations, financial condition and cash flow.

Based on analysis from its inception through December 31, 2016, the Company experienced Section 382 ownership changes in September 2001 and March 2003 and one of its subsidiaries experienced Section 382 ownership changes in January 2006 and January 2011 and the reported deferred tax assets reflect these expected limitations. These ownership changes limited the Company's ability to utilize federal net operating loss carryforwards (and certain other tax attributes) that accrued prior to the respective ownership changes of the Company and one of its subsidiaries. Additional ownership changes may occur in the future as a result of events over which the Company will have little or no control, including purchases and sales of the Company’s equity by our 5% stockholders, the emergence of new 5% stockholders, additional equity offerings or redemptions of the Company’s stock or certain changes in the ownership of any of the Company’s 5% stockholders.

A reconciliation of income taxes at the statutory federal income tax rate to net income tax expense (benefit) included in the accompanying statements of operations is set forth in the following table:



	Year ended December 31,
	2017		2016		2015
U.S. federal income tax expense (benefit) at the statutory rate	(35.00	)%	(35.00	)%	(35.00	)%
Available research and experimentation tax credits	—		—		(2.30	)
State income taxes, net of federal taxes	(0.03	)	0.88		(0.50	)
Loss in foreign subsidiary	7.36		15.88		43.60
Valuation allowance, including impact of tax reform	24.10		12.07		13.70
Other	2.80		0.25		0.50
Total	(0.77	)%	(5.92	)%	20.00	%

The loss in foreign subsidiary reconciling item in the above table is the tax effect of intercompany research and development expenses which are not deductible on the Company's consolidated federal income tax return.

The Company accounts for the effect of any uncertain tax positions based on a more likely than not threshold to the recognition of the tax positions being sustained based on the technical merits of the position under scrutiny by the applicable taxing authority. If a tax position or positions are deemed to result in uncertainties of those positions, the unrecognized tax position is estimated based on a cumulative probability assessment that aggregates the estimated tax liability for all uncertain tax positions. Interest and penalties assessed, if any, are accrued and recorded in either interest expense or miscellaneous expense, respectively in the consolidated statement of operations. During the year ended December 31, 2017, the Company recorded interest and penalties relating to its uncertain tax position of $335,000 in its consolidated statement of operations in interest expense and other expenses. No interest or penalties were recorded for the years ended December 31, 2016 and 2015. The liability for uncertain tax benefits consists of estimated federal and state income tax liabilities in years for which the statute of limitations is open. Open years range from 2014 through 2016.

The changes in the Company's uncertain income tax positions for the year ended December 31, 2017 consisted of the following (in thousands):




	December 31, 2017
Beginning Balance - uncertain tax positions	$	653
Increases for tax positions related to current year	—
Decreases due to settlements with taxing authorities	—
Reductions due to lapsed statute of limitations	—
Ending Balance - uncertain tax positions	$	653

The Company does not anticipate the liability for uncertain tax positions as of December 31, 2017 to significantly change in the next 12 months. The Company is currently under IRS examination for its federal tax returns for the years ending December 31, 2016 and 2014.

Loss Per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Loss Per Share

The following table presents the calculations of loss per share:



	Years Ended December 31,
	2017			2016			2015
Historical net loss per share
Numerator
Net loss attributable to common stockholders	$	(71,951	)	$	(85,155	)	$	(40,381	)

Denominator
Basic and diluted weighted-average shares outstanding	31,304,309			28,979,327			28,586,585

Basic and diluted loss per share	$	(2.30	)	$	(2.94	)	$	(1.41	)

All common stock equivalents are excluded from the computation of diluted loss per share during periods in which losses are reported since the result would be anti-dilutive. For December 31, 2017, anti-dilutive stock options and restricted stock awards excluded from our calculation totaled 7,202,221 and 168,221, respectively. For December 31, 2016, anti-dilutive stock options and restricted stock awards excluded from our calculation totaled 6,278,542 and 288,964.

Licensing Agreements

12 Months Ended

Dec. 31, 2017

Licensing Agreements [Abstract]

Licensing Agreements

The Company is a party to a number of licensing agreements with respect to certain of the technologies that underlie its intellectual property. These agreements typically provide that the Company has exclusive rights to the use and sublicensing of the technologies in question for the duration of the intellectual property patent protection in question, subject to the Company meeting its financial and other contractual obligations under the agreements. The Company recognizes expense under its licensing agreements in the period the obligation is incurred. These agreements typically provide for a license fee based on a percent of sales and annual minimum royalties. For additional information regarding how the Company records payments under these agreements, see Note 2 above. The Company has incurred expense of approximately $1.4 million, $2.0 million, and $2.0 million, under all of the in-licensing agreements for the years ended December 31, 2017, 2016, and 2015, respectively, which is recorded as a component of general and administrative expenses.

Under certain license agreements the Company is obligated to make potential milestone payments as listed in the following table. In addition to the milestone payments, each license is paid as a low single-digit percentage of net sales of the licensed product, subject to annual minimum royalties. These obligations are contingent upon achieving the applicable milestone event, the timing of which cannot presently be determined. The milestone payments and royalty payments are in place through at least the expiration of certain of the Company's patents, which is currently 2029 and beyond.



Licensor		Aggregate potential milestone payments
Augusta University Research Institute under AURI IDO		$2.8 million per licensed product

Augusta University Research Institute under the AURI PTEN Agreement		$4.3 million in total

Public Health Agency of Canada		C$475,000

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans The Company sponsors a 401(k) plan, which includes a defined contribution feature. The Company's defined contribution was $361,000, $482,000, $361,000 for the years ended December 31, 2017, 2016 and 2015, respectively. The Company made discretionary contributions to the plan of $401,000, $446,000, and $319,000 for the years ended December 31, 2017, 2016 and 2015, respectively. The Company has approved employment agreements for certain executives, dated October 29, 2010, as amended January 4, 2016, that provide for the payment of 6 to 24 months of base salary, bonus, and group health insurance premiums plus accrued obligations upon termination of the executive in certain circumstances. The agreements include provisions to accelerate the vesting of stock options subject to certain events including those related to a change in control. The Company entered into the January 2016 amendments to the foregoing agreements, upon recommendation by the Compensation Committee of the Board of Directors, to align the terms of certain termination benefits with termination terms for executive officers at similarly situated companies to the Company.

Restructuring Charges

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Restructuring Charges

The Company records liabilities for costs associated with exit or disposal activities in the period in which the liability is incurred. Employee severance costs are accrued when the restructuring actions are probable and estimable. Costs for one-time termination benefits in which the employee is required to render service until termination in order to receive the benefits are recognized ratably over the future service period. The Company also records costs incurred with contract terminations associated with restructuring activities.

In July 2017, the Company undertook an organizational realignment to refocus its clinical development efforts and align the Company's resources to focus on the Company's highest value opportunities. The Company's restructuring activities included a reduction of its workforce by approximately 50%, which consisted primarily of clinical and research and development staff, as well as stopping additional research on the Zika virus. Restructuring charges recorded during 2017 included $1.7 million, of which $1.1 million is included within general and administrative expenses and $600,000 is included within research and development expenses in the consolidated statement of operations. The charges include employee severance costs of one-time employee termination benefits and certain expenses related to contractual termination benefits for employees with pre-existing severance arrangements.

In May 2016, the Company announced that its Phase 3 clinical trial Immunotherapy for Pancreatic RESectable cancer Study, or IMPRESS, of algenpantucel-L for patients with resected pancreatic cancer did not achieve its primary endpoint and in order to reduce costs associated with algenpantucel-L and the HyperAcute® Cellular Immunotherapy platform technology, the Company's management adopted a restructuring plan in May 2016 which included a reduction in the Company's workforce; the exit or reduction of certain leased facilities; and the renegotiation or termination of contracts with certain third parties. As a result of the restructuring, the Company also impaired fixed assets which management determined had no or limited future use. The fair value of impaired fixed assets was determined based on management’s estimate of market resale value. Restructuring charges recorded during 2016 were $11.6 million, of which $500,000 is included general and administrative expenses and $11.1 million is included within the research and development expenses in the consolidated statement of operations. Included in the $11.6 million of charges is non-cash asset impairment charges of $4.0 million. There were no restructuring charges recorded in 2015.

The following table shows the amount accrued for restructuring activities which is recorded within Accrued Expenses in the consolidated balance sheet (in thousands):



	Employee Severance Cost		Total
Balance as of December 31, 2016	$	42	$	42
Expensed	1,735		1,735
Cash Payments	1,570		1,570
Adjustments	—		—
Balance as of December 31, 2017	$	207	$	207

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies From time to time, claims are asserted against the Company arising in the ordinary course of business. In the opinion of management, liabilities, if any, arising from existing claims are not expected to have a material effect on the Company's earnings, financial position, or liquidity. On or about May 12, 2016, Trevor Abramson filed a putative securities class action lawsuit in the United States District Court for the Southern District of New York, or the Court, captioned Abramson v. NewLink Genetics Corp., et al., Case 1:16-cv-3545, or the Securities Action. Subsequently, the Court appointed Michael and Kelly Nguyen as lead plaintiffs and approved their selection of Kahn, Swick & Foti, LLC as lead counsel in the Securities Action. On October 31, 2016, the lead plaintiffs filed an amended complaint which asserts claims under the federal securities laws against the Company, the Company’s Chief Executive Officer Charles J. Link, Jr., and the Company’s Chief Medical Officer and President Nicholas Vahanian, or collectively, the Defendants. The amended complaint alleges the Defendants made material false and/or misleading statements that caused losses to the Company’s investors. In particular, the lead plaintiffs allege that the Defendants made material misstatements or omissions related to the Phase II and III trials and efficacy of the product candidate algenpantucel-L. The lead plaintiffs do not quantify any alleged damages in the amended complaint but, in addition to attorneys’ fees and costs, they seek to recover damages on behalf of themselves and other persons who purchased or otherwise acquired the Company’s stock during the putative class period of September 17, 2013 through May 9, 2016, inclusive, at allegedly inflated prices and purportedly suffered financial harm as a result. On April 27, 2017, the Court granted the parties’ request for leave to brief a motion to dismiss the amended complaint, and ordered the parties to file a stipulation and proposed order setting forth a schedule for the briefing of that motion. On May 15, 2017, the Court ordered the following briefing schedule: motion to dismiss due July 14, 2017, opposition due September 12, 2017, and reply due September 26, 2017. The Defendants filed a motion to dismiss on July 14, 2017. The lead plaintiffs filed an opposition to the motion to dismiss on September 12, 2017. The Defendants filed a reply in support of the motion to dismiss on September 26, 2017. Oral argument was held on October 19, 2017, after which the Court reserved decision. The Company disputes the claims in the Securities Action and intends to defend against them vigorously. On or about April 26, 2017, Ronald Morrow filed a shareholder derivative lawsuit on behalf of the Company in the United States District Court for the Southern District of New York, or the Court, against the Company’s Chief Executive Officer Charles J. Link, Jr., the Company’s Chief Medical Officer and President Nicholas Vahanian, and Company directors Thomas A. Raffin, Joseph Saluri, Ernest J. Talarico, III, Paul R. Edick, Paolo Pucci, and Lota S. Zoth, or collectively, the Morrow Defendants, captioned Morrow v. Link., et al., Case 1:17-cv-03039, or the Morrow Action. The complaint alleges that the Morrow Defendants caused the Company to issue false statements in its 2016 proxy statement regarding risk management and compensation matters in violation of federal securities law. The complaint also asserts state law claims against the Morrow Defendants for breaches of fiduciary duties, unjust enrichment, abuse of control, insider trading, gross mismanagement, and corporate waste, alleging that the Morrow Defendants made material misstatements or omissions related to the Phase II and III trials and efficacy of the product candidate algenpantucel-L, awarded themselves excessive compensation, engaged in illegal insider trading, and grossly mismanaged the Company. The plaintiff does not quantify any alleged damages in the complaint but seeks restitution for damages to the Company, attorneys’ fees, costs, and expenses, as well as an order directing that proposals for strengthening board oversight be put to a vote of the Company’s shareholders. The language for such proposals is not specified in the complaint. The plaintiff also contemporaneously filed a statement of relatedness, informing the Court that the Morrow Action is related to Abramson v. NewLink Genetics Corp., et al., Case 1:16-cv-3545. On May 19, 2017, the plaintiff dismissed the Morrow Action without prejudice. Also on May 19, 2017, plaintiffs’ counsel in the Morrow Action filed a new shareholder derivative complaint that is substantively identical to the Morrow Action, except that the plaintiff is Rickey Ely. The latter action is captioned Ely v. Link, et al., Case 17-cv-3799, or the Ely Action. By agreement of the parties and order dated June 26, 2017, the Court temporarily stayed the Ely Action until the Securities Action is dismissed or otherwise resolved. Under the terms of the stay, the plaintiff in the Ely Action will be provided with any discovery that is provided in the Securities Action, and given an opportunity to participate in any mediation or settlement efforts in the Securities Action. The Company disputes the claims in the Ely Action and intends to defend against them vigorously.

Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information (Unaudited)



	First			Second			Third			Fourth
	(In thousands, except per share data)
Year Ended December 31, 2017
Grant and licensing revenue	$	2,761		$	10,370		$	5,482		$	10,098
Loss from operations	(21,198		)	(16,727		)	(20,905		)	(14,051		)
Net loss	(20,913		)	(16,726		)	(20,626		)	(13,686		)
Basic and diluted loss per share	$	(0.72	)	$	(0.57	)	$	(0.69	)	$	(0.37	)
Year Ended December 31, 2016
Grant and licensing revenue	$	5,708		$	2,012		$	15,345		$	12,703
Loss from operations	(25,393		)	(34,528		)	(16,687		)	(13,970		)
Net loss ⁽¹⁾	(23,720		)	(32,389		)	(15,540		)	(13,506		)
Basic and diluted loss per share	$	(0.82	)	$	(1.12	)	$	(0.54	)	$	(0.46	)

(1)

In the fourth quarter of 2016, the Company adopted ASU 2016-09 which required adoption as of January 1, 2016. In the second and third quarter of 2016, the Company recorded an income tax benefit and an increase to additional paid in capital of $127,000 and $513,000, respectively, which is reflected in the above quarterly financial information (unaudited) as reported. Adoption allows for the recognition of excess tax benefits in the income tax provision rather than as paid-in capital. This resulted in the reversal of the prior quarter entries, including tax expense of $640,000 recorded in the fourth quarter of 2016.

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles, or U.S. GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the financial statements of NewLink and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Cash and Cash Equivalents	Cash and Cash Equivalents For the purposes of the consolidated statements of cash flows, the Company considers all highly liquid debt instruments with an original maturity of three months or less to be cash equivalents.
Leasehold Improvements and Equipment, and Deferred Rent	Leasehold Improvements and Equipment, and Deferred Rent Leasehold improvements and equipment are capitalized as the Company believes they have alternative future uses and are stated at cost. Equipment under capital leases is stated at the present value of future minimum lease payments. Depreciation on all leasehold improvements and equipment is calculated on the straight-line method over the shorter of the lease term or estimated useful life of the asset. Computer equipment has useful lives of three to five years, lab equipment has a useful life of five years and contract manufacturing organization equipment has a useful life of five years. Deferred rent reflects improvement allowances from the Company's lessors deferred to be recognized as part of lease expense over the remaining term of the lease, which is recognized on a straight-line basis.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset group to future net undiscounted cash flows expected to be generated by the asset group, primarily relating to proceeds for selling the assets. If such assets are considered to be impaired, the impairment to be recognized is measured at the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or fair value less costs to sell.
Revenue Recognition	Revenue Recognition The Company recognizes revenue for the performance of services or the shipment of products when each of the following four criteria is met: (1) persuasive evidence of an arrangement exists; (2) products are delivered or as services are rendered; (3) the sales price is fixed or determinable; and (4) collectability is reasonably assured. The Company receives payments from government entities under its grants and contracts with the National Institute of Health, the Department of Defense, and the United States Department of Health and Human Services. These agreements provide the Company cost reimbursement plus a percentage for certain types of expenditures in return for research and development activities over a contractually defined period. Grant revenues are recognized in the period during which the related costs are incurred, provided that the conditions under which the costs submitted or to be submitted for reimbursement have been met and the Company has only perfunctory obligations outstanding. During the years ended December 31, 2017, 2016, and 2015, the Company has earned $28.3 million, $32.2 million, and $32.4 million in grant revenue, respectively. The Company had $9.3 million and $23.9 million of receivables from the government contracts recorded in other receivables and $465,000 and $4.3 million of unbilled expenses relating to the government contracts recorded in prepaid expenses and other assets on the balance sheet as of December 31, 2017 and 2016, respectively. The Company had $1.8 million and $2.9 million of accrued expenses for subcontractor fees and $4.9 million and $19.3 million of subcontractor fees in accounts payable for amounts incurred under the government contracts as of December 31, 2017 and 2016, respectively. The Company follows ASC 605-25, Revenue Recognition - Multiple-Element Arrangements and ASC 808, Collaborative Arrangements , if applicable, to determine the recognition of revenue under our license and collaborative research, development and commercialization agreements. The terms of these agreements generally contain multiple elements, or deliverables, which may include (1) licenses to our intellectual property, (2) materials and technology, (3) clinical supply, and/or (4) participation on joint research or joint steering committees. The payments the Company may receive under these arrangements typically include one or more of the following: non-refundable, up-front license fees; funding of research and/or development efforts; amounts due upon the achievement of specified milestones; and/or royalties on future product sales. ASC 605-25 provides guidance relating to the separability of deliverables included in an arrangement into different units of accounting and the allocation of arrangement consideration to the units of accounting. The evaluation of multiple-element arrangements requires management to make judgments about (1) the identification of deliverables, (2) whether such deliverables are separable from the other aspects of the contractual relationship, (3) the estimated selling price of each deliverable, and (4) the expected period of performance for each deliverable. To determine the units of accounting under a multiple-element arrangement, management evaluates certain separation criteria, including whether the deliverables have stand-alone value, based on the relevant facts and circumstances for each arrangement. Management then estimates the selling price for each unit of accounting and allocates the arrangement consideration to each unit utilizing the relative selling price method. The allocated consideration for each unit of accounting is recognized over the related obligation period in accordance with the applicable revenue recognition criteria. If there are deliverables in an arrangement that are not separable from other aspects of the contractual relationship, they are treated as a combined unit of accounting, with the allocated revenue for the combined unit recognized in a manner consistent with the revenue recognition applicable to the final deliverable in the combined unit. Payments received prior to satisfying the relevant revenue recognition criteria are recorded as unearned revenue in the accompanying balance sheets and recognized as revenue when the related revenue recognition criteria are met. The Company typically receives non-refundable, up-front payments when licensing our intellectual property, which often occurs in conjunction with a research and development agreement. If management believes that the license to our intellectual property has stand-alone value, the Company generally recognizes revenue attributed to the license upon delivery provided that there are no future performance requirements for use of the license. When management believes that the license to our intellectual property does not have stand-alone value, the Company would recognize revenue attributed to the license on a straight-line basis over the contractual or estimated performance period. When the performance period is not specifically identifiable from the agreement, the Company would estimate the performance period based upon provisions contained within the agreement, such as the duration of the research or development term. For payments payable on achievement of milestones that do not meet all of the conditions to be considered substantive, the Company recognizes a portion of the payment as revenue when the specific milestone is achieved, and the contingency is removed. Other contingent event-based payments for which payment is either contingent solely upon the passage of time or the result of collaborator's performance are recognized when earned.
Expenses Accrued Under Contractual Arrangements with Third Parties; Accrued Clinical Expenses	Expenses Accrued Under Contractual Arrangements with Third Parties; Accrued Clinical Expenses The Company estimates its accrued expenses through a process of reviewing open contracts and purchase orders, communicating with personnel to identify services that have been performed and estimating the level of service performed and the associated cost incurred for the service that may not be invoiced from the provider. The estimates of accrued expenses as of each balance sheet date are based on facts and circumstances known at that time. Such estimates are periodically confirmed with the service providers to verify accuracy. The Company bases its expenses related to clinical trials on estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and contract research organizations that conduct and manage clinical trials on behalf of the Company. Invoicing from third-party contractors for services performed can lag several months. The Company accrues the costs of services rendered in connection with third-party contractor activities based on its estimate of management fees, site management and monitoring costs and data management costs as contracted. Differences between actual clinical trial costs and estimated clinical trial costs are adjusted for in the period in which they become known through operations.
Research and Development	Research and Development Research and development costs are expensed as incurred. Research and development expenses consist primarily of employee-related expenses, which include salaries, bonuses, benefits and share-based compensation; manufacturing-related costs; clinical trial expenses which include expenses incurred under agreements with contract research organizations, investigative sites and consultants that conduct our clinical trials; facilities, depreciation of fixed assets and other allocated expenses, which include direct and allocated expenses for rent and maintenance of research facilities and equipment; license fees for and milestone payments related to in-licensed products and technology; and costs associated with non-clinical activities and regulatory approvals.
Patents	Patents The Company generally applies for patent protection on processes and products. Patent application costs are expensed as incurred as a component of general and administrative expense, as recoverability of such expenditures is uncertain.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using 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 operating results in the period that includes the enactment date. Management assesses the realizability of deferred tax assets and records a valuation allowance if it is more likely than not that all or a portion of the deferred tax assets will not be realized. The Company accounts for the effect of any uncertain tax positions based on a more likely than not threshold to the recognition of the tax positions being sustained based on the technical merits of the position under scrutiny by the applicable taxing authority. If a tax position or positions are deemed to result in uncertainties of those positions, the unrecognized tax position is estimated based on a cumulative probability assessment that aggregates the estimated tax liability for all uncertain tax positions. Interest and penalties assessed, if any, are recorded in its consolidated statement of operations in interest expense and other expenses.
Share-Based Compensation	Share-Based Compensation The Company is required to estimate the grant-date fair value of share-based payment transactions with employees which include stock options, restricted stock units (RSUs) and performance shares (PSUs) and recognizes the compensation cost over the requisite service period based on the estimated fair values as well as expected forfeiture rates. The Company estimates the fair value of each award granted using the Black-Scholes option pricing model. The Black-Scholes model requires the input of assumptions, including the expected stock price volatility, the calculation of expected term and the fair value of the underlying common stock on the date of grant, among other inputs. The Company calculates the fair value of the award on the grant date, which is the date the award is authorized by the Board of Directors or Chief Executive Officer and the employee has an understanding of the terms of the award. Generally, the Company has issued employee awards that vest either monthly or 25% vest on the first anniversary date of issuance with the remaining options vesting ratably over the next 36 months. The Company records compensation cost on a straight-line basis over the vesting period. The fair value of RSUs that are subject to cliff vesting are recognized as compensation expense over the requisite service period using the straight line attribution method, and the fair value of RSUs that are subject to graded vesting are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of PSUs are recognized as compensation expense beginning at the time in which the performance conditions are deemed probable of achievement, over the remaining requisite service period. The Company has issued awards to nonemployee consultants and advisers. All grants to nonemployees are valued using the same fair value method that we use for grants to employees. The compensation cost on these awards is measured each period until vesting, and is recognized through the earlier of the vesting of the award or completion of services by the nonemployee. Following is a description of the inputs for the Black-Scholes model: Exercise Price The Company uses the quoted market price as listed on the public exchange on the date of grant. If Incentive Stock Options are granted to a 10% stockholder in the Company, the exercise price shall not be less than 110% of the common stock’s fair market value on the date of grant. Expected Term (in Years) The expected term of a stock option is the period of time for which the option is expected to be outstanding. The Company uses historical exercise and option expiration data to estimate the expected term for the Black-Scholes grant-date valuation. Risk-Free Interest Rate The Company uses the average yield on current U.S. Treasury instruments with terms that approximate the expected term of the stock options being valued. Expected Dividend Yield The expected dividend yield for all of the Company’s stock option grants is 0%, as the Company has not declared a cash dividend since inception and has no plans to declare a dividend. Expected Volatility The Company uses its historical stock price volatility. The volatility is calculated over a period of time commensurate with the expected term for the options granted. Forfeitures The share-based compensation expense has been reduced for estimated forfeitures. The estimated forfeiture rate is based on historical experience of the Company’s option plan, which the Company expects to continue at the current level, and any adjustments in the forfeiture rate in the future will result in a cumulative adjustment in the period that this estimate is changed. Ultimately, the total compensation expense recognized for any given stock-based award over its vesting period will only be for those shares that actually vest.
Segments	Segments The Company operates in one segment. The Company conducts research and development activities based from facilities located in Ames, Iowa and has corporate headquarters in Ames, Iowa and Austin, Texas. The Company conducts preclinical and clinical research in the biopharmaceutical industry. The chief operating decision maker uses cash flow as the primary measure to manage the business and management does not segment its business for internal reporting or decision-making.
Financial Instruments	Financial Instruments and Concentrations of Credit Risk The fair values of cash and cash equivalents, receivables and accounts payable, which are recorded at cost, approximate fair value based on the short-term nature of these financial instruments. The fair value of notes payable and capital lease obligations was $271,000 and $517,000 as of December 31, 2017 and 2016, respectively, and was determined using Level 2 inputs (computed in accordance with ASC 820). The Company is unable to estimate the fair value of the royalty obligation based on future product sales as the timing of payments, if any, is uncertain.
Concentrations of Credit Risk	Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. Cash and cash equivalents are held by financial institutions and are federally insured up to certain limits. At times, the Company’s cash and cash equivalents balance exceeds the federally insured limits. To limit the credit risk, the Company invests its excess cash primarily in high quality securities such as money market funds.
Earnings Per Share	Earnings per share (EPS) The Company computes basic EPS attributable to the Company's common stockholders by dividing net income (loss) attributable to the Company by our weighted-average common shares outstanding during the period. Diluted EPS reflects the potential dilution beyond shares for basic EPS that could occur if securities or other contracts to issue common stock were exercised, converted into common stock, or resulted in the issuance of common stock that would have shared in our earnings. The Company computes basic and diluted EPS using net income (loss) attributable to the Company's common stockholders, and its actual weighted-average shares.
Recent Accounting Pronouncements	Recent Accounting Pronouncements On May 28, 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The new standard is effective for the Company on January 1, 2018. The standard permits the use of either the retrospective or cumulative effect transition method. The Company will adopt the standard on a modified retrospective basis at January 1, 2018, with an adjustment for the cumulative effect of all changes recognized in beginning retained earnings. The Company has completed its analysis of the adoption impact and will record an immaterial entry to beginning retained earnings. In February 2016, the Financial Accounting Standards Board, or the FASB, issued ASU No. 2016-02, Leases, to improve financial reporting for leasing transactions. The new standard requires lessees to recognize on the balance sheet a right of use asset and related lease liability for all leases with terms greater than twelve months. The ASU also requires disclosures about the amount, timing, and uncertainty of cash flows arising from leases. The effective date for public entities is fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted for all entities. The Company does not currently have any material leases and therefore does not anticipate adoption to have a material impact on its consolidated financial statements and related disclosures.

Leases (Tables)

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Capital Leased Assets

The following is an analysis of the leased property under capital leases by major class (in thousands):



	Asset Balances at December 31,
Class of property	2017			2016
Lab equipment	$	720		$	720
Leasehold improvements	27			27
Computer equipment	54			54
Total property under capital leases	801			801
Less accumulated depreciation and amortization	(652		)	(586		)
Capital leased assets, net	$	149		$	215

Minimum Lease Payments for Capital Leases

The following is a schedule of the future minimum lease payments under capital leases together with the present value of the net minimum lease payments as of December 31, 2017 (in thousands):



Year Ending December 31:
2018	$	74
Less amount representing interest	(1		)
Present value of net minimum lease payments	$	73

Minimum Rental Payments for Operating Leases

Future minimum lease payments under the noncancelable operating leases (with initial or remaining lease terms in excess of one year) as of December 31, 2017 are as follows (in thousands):



Year Ending December 31:
2018	$	1,157
2019	1,104
2020	1,008
Thereafter	9,391
Total	$	12,660

Leasehold improvements and equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Schedule of Leasehold Improvements and Equipment

Leasehold improvements and equipment at December 31, 2017 and 2016 consisted of the following:



	Year Ended December 31,
	2017			2016
Leasehold improvements	$	5,310		$	5,310
Computer and office equipment	2,326			2,219
Lab and leased equipment	3,979			4,056
Contract manufacturing organization equipment	114			486
Assets not placed in service	—			490
Total leasehold improvements and equipment	11,729			12,561
Less accumulated depreciation and amortization	(6,638		)	(5,726		)
Total leasehold improvements and equipment, net	$	5,091		$	6,835

Common Stock Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Authorized Increases under 2009 Stock Plan

The following table summarizes the authorized increases of common stock under the 2009 Plan:



Date Authorized		Authorized Shares Added
May 15, 2010		1,238,095
January 7, 2011		714,286
January 1, 2013		838,375
January 1, 2014		1,066,340
January 1, 2015		1,119,255
January 1, 2016		1,152,565
January 1, 2017		1,166,546

Stock Option Activity

The following table summarizes the stock option activity for the year ended December 31, 2017:



	Number of options		Weighted average exercise price		Weighted average remaining contractual term (years)
Outstanding at beginning of period	6,278,542		$	14.93
Options granted	1,526,787		11.61
Options exercised	(120,716	)	7.96
Options forfeited	(324,947	)	19.88
Options expired	(157,445	)	33.27
Outstanding at end of period	7,202,221		13.72		5.3
Options exercisable at end of period	5,489,349		$	12.51	4.3

Assumptions Used in Black-Scholes Pricing Model for New Grants



	Years Ended December 31,
	2017	2016	2015
Number of options granted	1,526,787	1,346,758	1,019,445
Risk-free interest rate	1.91%-2.22%	1.19%-1.97%	1.51%-2.00%
Expected dividend yield	—	—	—
Expected volatility	68.9%-76.88%	67.1%-69.8%	62.5%-67.3%
Expected term (in years)	1.2-7.8	5.9-7.4	5.9-7.0
Weighted average grant-date fair value per share	$7.72	$11.91	$26.36

Intrinsic Value of options exercised and Fair Value of awards vested

The following table summarizes the intrinsic value of options exercised and the fair value of awards vested during the years ended December 31, 2017, 2016 and 2015:

Restricted Stock Activity

A summary of the Company's unvested restricted stock at December 31, 2017 and changes during the year ended December 31, 2017 is as follows:



	Restricted Stock		Weighted Average Grant Date Fair Value
Unvested at beginning of period	288,964		$	34.94
Granted	—		—
Vested	(92,245	)	33.70
Forfeited/cancelled	(28,498	)	33.72
Unvested at end of period	168,221		$	35.82

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income tax expense

Income tax benefit (expense) consists of (in thousands):



	Current			Deferred		Total
Year Ended December 31, 2017:
U.S. federal	$	332		$	140	$	472
State and local	87			—		87
	$	419		$	140	$	559

Year Ended December 31, 2016:
U.S. federal	$	6,469		$	—	$	6,469
State and local	(1,113		)	—		(1,113		)
	$	5,356		$	—	$	5,356

Year Ended December 31, 2015:
U.S. federal	$	(5,522	)	$	—	$	(5,522	)
State and local	(1,216		)	—		(1,216		)
	$	(6,738	)	$	—	$	(6,738	)

Income tax rate reconciliation



	Year ended December 31,
	2017		2016		2015
U.S. federal income tax expense (benefit) at the statutory rate	(35.00	)%	(35.00	)%	(35.00	)%
Available research and experimentation tax credits	—		—		(2.30	)
State income taxes, net of federal taxes	(0.03	)	0.88		(0.50	)
Loss in foreign subsidiary	7.36		15.88		43.60
Valuation allowance, including impact of tax reform	24.10		12.07		13.70
Other	2.80		0.25		0.50
Total	(0.77	)%	(5.92	)%	20.00	%

Schedule of deferred tax assets and liabilities

The tax effects of temporary differences that give rise to significant portions of deferred tax assets and the deferred tax liability at December 31, 2017 and 2016 are presented below (in thousands):



	Year Ended December 31,
	2017			2016
Deferred tax assets:
Net operating loss carryforwards	$	10,622		$	654
Federal research and development tax credits	26,327			20,836
Share-based compensation	11,780			11,843
Deferred rent	327			491
Minimum tax credits	—			143
Accrued compensation	789			427
Unearned revenue	17			163
Charitable contributions	39			13
Leasehold improvements and equipment	297			552
Gross deferred tax assets	50,198			35,122
Less valuation allowance	(50,198		)	(35,122		)
Total deferred tax assets	—			—

Uncertain income tax positions

The changes in the Company's uncertain income tax positions for the year ended December 31, 2017 consisted of the following (in thousands):




	December 31, 2017
Beginning Balance - uncertain tax positions	$	653
Increases for tax positions related to current year	—
Decreases due to settlements with taxing authorities	—
Reductions due to lapsed statute of limitations	—
Ending Balance - uncertain tax positions	$	653

Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Basic and Diluted Net Loss per Common Share

The following table presents the calculations of loss per share:



	Years Ended December 31,
	2017			2016			2015
Historical net loss per share
Numerator
Net loss attributable to common stockholders	$	(71,951	)	$	(85,155	)	$	(40,381	)

Denominator
Basic and diluted weighted-average shares outstanding	31,304,309			28,979,327			28,586,585

Basic and diluted loss per share	$	(2.30	)	$	(2.94	)	$	(1.41	)

Licensing Agreements (Tables)

12 Months Ended

Dec. 31, 2017

Licensing Agreements [Abstract]

Licensing Agreements



Licensor		Aggregate potential milestone payments
Augusta University Research Institute under AURI IDO		$2.8 million per licensed product

Augusta University Research Institute under the AURI PTEN Agreement		$4.3 million in total

Public Health Agency of Canada		C$475,000

Restructuring Charges (Tables)

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Restructuring Charges

The following table shows the amount accrued for restructuring activities which is recorded within Accrued Expenses in the consolidated balance sheet (in thousands):



	Employee Severance Cost		Total
Balance as of December 31, 2016	$	42	$	42
Expensed	1,735		1,735
Cash Payments	1,570		1,570
Adjustments	—		—
Balance as of December 31, 2017	$	207	$	207

Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information (Unaudited)



	First			Second			Third			Fourth
	(In thousands, except per share data)
Year Ended December 31, 2017
Grant and licensing revenue	$	2,761		$	10,370		$	5,482		$	10,098
Loss from operations	(21,198		)	(16,727		)	(20,905		)	(14,051		)
Net loss	(20,913		)	(16,726		)	(20,626		)	(13,686		)
Basic and diluted loss per share	$	(0.72	)	$	(0.57	)	$	(0.69	)	$	(0.37	)
Year Ended December 31, 2016
Grant and licensing revenue	$	5,708		$	2,012		$	15,345		$	12,703
Loss from operations	(25,393		)	(34,528		)	(16,687		)	(13,970		)
Net loss ⁽¹⁾	(23,720		)	(32,389		)	(15,540		)	(13,506		)
Basic and diluted loss per share	$	(0.82	)	$	(1.12	)	$	(0.54	)	$	(0.46	)

(1)

Description of Business Activities (Details)					1 Months Ended	3 Months Ended	12 Months Ended
Description of Business Activities (Details)	Oct. 06, 2017 USD ($) shares	Nov. 29, 2016 USD ($)	Feb. 04, 2013 USD ($)	Nov. 16, 2011 USD ($)	Feb. 28, 2015 USD ($)	Mar. 30, 2015 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2014 USD ($) arrangement
Summary of Financings
Number of license and collaboration arrangements \| arrangement								2
Collaborative Arrangement \| Genentech Inc.
Summary of Financings
Upfront cash payments								$ 150,000,000
Collaborative Arrangement \| Merck, Sharpe and Dohme Corp
Summary of Financings
Upfront cash payments					$ 20,000,000.0			$ 30,000,000
IPO
Summary of Financings
Financing proceeds				$ 37,600,000
Follow-on Offering
Summary of Financings
Financing proceeds			$ 49,000,000
ATM Offering
Summary of Financings
Financing proceeds						$ 58,700,000	$ 19,300,000
Maximum available under ATM offering		$ 40,000,000
Public Offering
Summary of Financings
Financing proceeds	$ 55,200,000
Offering costs	$ 3,700,000
Number of shares issued \| shares	5,750,000

Significant Accounting Policies (Details) - USD ($)	3 Months Ended								12 Months Ended
Significant Accounting Policies (Details) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents
Cash and cash equivalents	$ 158,708,000				$ 131,490,000				$ 158,708,000	$ 131,490,000	$ 195,620,000	$ 190,404,000
Leasehold Improvements and Equipment
Deferred rents	1,100,000				1,200,000				1,100,000	1,200,000
Revenue Recognition
Grant revenue									28,321,000	32,242,000	32,358,000
Receivables from government contracts	9,300,000				23,900,000				9,300,000	23,900,000
Unbilled expenses	465,000				4,300,000				465,000	4,300,000
Effective Income Tax Rate Reconciliation, percent
Uncertain Tax Positions	653,000				653,000				$ 653,000	653,000
Stock Option Valuation
Award vesting percentage									25.00%
Award vesting period									36 months
Expected dividend yield									0.00%
Notes payable and capital lease obligations	271,000				517,000				$ 271,000	517,000
Grant and licensing revenue	10,098,000	$ 5,482,000	$ 10,370,000	$ 2,761,000	12,703,000	$ 15,345,000	$ 2,012,000	$ 5,708,000	$ 28,700,000	$ 35,800,000	$ 68,500,000
Customer Concentration Risk \| Sales Revenue, Net \| Genentech
Stock Option Valuation
Concentration risk percentage									1.20%	7.60%	21.50%
Customer Concentration Risk \| Sales Revenue, Net \| Merck
Stock Option Valuation
Concentration risk percentage									0.20%	2.30%	31.30%
Computer and office equipment \| Minimum
Property, Plant and Equipment [Line Items]
Useful life									3 years
Computer and office equipment \| Maximum
Property, Plant and Equipment [Line Items]
Useful life									5 years
Lab and leased equipment
Property, Plant and Equipment [Line Items]
Useful life									5 years
Contract manufacturing organization equipment
Property, Plant and Equipment [Line Items]
Useful life									5 years
Accrued Expenses
Revenue Recognition
Accrued expenses for subcontractor fees incurred under government contracts	1,800,000				2,900,000				$ 1,800,000	$ 2,900,000
Accounts Payable
Revenue Recognition
Subcontractor fees in accounts payable	$ 4,900,000				$ 19,300,000				$ 4,900,000	$ 19,300,000

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capital Leases, Lessee Balance Sheet [Abstract]
Total property under capital leases	$ 801	$ 801
Less accumulated depreciation and amortization	(652)	(586)
Capital leased assets, net	149	215
Capital Leases
2018	74
Less amount representing interest	(1)
Present value of net minimum lease payments	73
Rent expense	1,200	1,700	$ 1,700
Operating Leases
2018	1,157
2019	1,104
2020	1,008
Thereafter	9,391
Total	$ 12,660
Minimum
Capital Leases
Term of lease contract	1 year
Maximum
Capital Leases
Term of lease contract	5 years
Lab and leased equipment
Capital Leases, Lessee Balance Sheet [Abstract]
Total property under capital leases	$ 720	720
Leasehold improvements
Capital Leases, Lessee Balance Sheet [Abstract]
Total property under capital leases	27	27
Computer equipment
Capital Leases, Lessee Balance Sheet [Abstract]
Total property under capital leases	$ 54	$ 54

Leasehold improvements and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property Subject to or Available for Operating Lease [Line Items]
Total leasehold improvements and equipment	$ 11,729	$ 12,561
Less accumulated depreciation and amortization	(6,638)	(5,726)
Total leasehold improvements and equipment, net	5,091	6,835
Leasehold improvements
Property Subject to or Available for Operating Lease [Line Items]
Total leasehold improvements and equipment	5,310	5,310
Computer and office equipment
Property Subject to or Available for Operating Lease [Line Items]
Total leasehold improvements and equipment	2,326	2,219
Lab and leased equipment
Property Subject to or Available for Operating Lease [Line Items]
Total leasehold improvements and equipment	3,979	4,056
Contract manufacturing organization equipment
Property Subject to or Available for Operating Lease [Line Items]
Total leasehold improvements and equipment	114	486
Assets not placed in service
Property Subject to or Available for Operating Lease [Line Items]
Total leasehold improvements and equipment	$ 0	$ 490

Long-Term Debt Conversion to Royalty Obligation (Details)	1 Months Ended	12 Months Ended
	Mar. 31, 2010 USD ($) position	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2012	Dec. 31, 2009 USD ($)	Mar. 31, 2017 ft²	Dec. 31, 2014	Dec. 31, 2011 USD ($)	Mar. 31, 2005 USD ($)
Debt Instrument
Royalty obligation payable to Iowa Economic Development Authority		$ 6,000,000	$ 6,000,000
Grant revenue		28,321,000	32,242,000	$ 32,358,000
City of Ames Forgivable Loan 2010
Debt Instrument
Grant revenue		$ 397,000
Loans Payable \| Iowa Department of Economic Development Loan 2005
Debt Instrument
Original Available Balance										$ 6,000,000
Outstanding balance									$ 6,000,000
Loans Payable \| Iowa Economic Development Authority Royalty Obligation 2012
Debt Instrument
Revised royalty rate		0.50%
Revised royalty maximum amount		$ 6,800,000
Royalty obligation payable to Iowa Economic Development Authority		6,000,000
Loans Payable \| Iowa State University Research Park Loan 2009
Debt Instrument
Original Available Balance						$ 800,000
Outstanding balance		$ 29,000	140,000
Debt term						8 years
Stated interest rate						3.00%		5.00%
Increase to interest rate after completion of improvements						5 years
Debt default rate		8.00%
Loans Payable \| Iowa State University Research Park Loan 2012
Debt Instrument
Original Available Balance		$ 456,000
Outstanding balance		$ 169,000	$ 227,000
Debt term					8 years
Stated interest rate		5.00%			3.00%
Increase to interest rate after completion of improvements					5 years
Debt default rate		8.00%
Loans Payable \| City of Ames Forgivable Loan 2010
Debt Instrument
Original Available Balance	$ 400,000
Jobs by March 10, 2015 \| position	150
Term of lease contract	5 years
Lease square feet \| ft²							20,000
Renewal term of lease	5 years

License and Research Collaboration Agreements (Details) - USD ($)	1 Months Ended	12 Months Ended
	Feb. 28, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Revenue Arrangement [Line Items]
Licensing and collaboration revenue		$ 390,000	$ 3,526,000	$ 36,143,000
Genentech Inc. \| Collaborative Arrangement
Deferred Revenue Arrangement [Line Items]
Upfront cash payments					$ 150,000,000
Potential additional milestone payments					561,000,000
Licensing and collaboration revenue		335,000	2,700,000	14,700,000
Alliance manager		335,000	670,000	502,000
Deferred revenue		$ 56,000	391,000	1,200,000
JRC revenue			180,000	151,000
Employee labor revenue			1,900,000	2,100,000
Program materials and technology transfer				9,400,000
Clinical supply revenue				2,500,000
Merck, Sharpe and Dohme Corp \| Collaborative Arrangement
Deferred Revenue Arrangement [Line Items]
Upfront cash payments	$ 20,000,000.0				$ 30,000,000
Licensing and collaboration revenue			815,300	21,400,000
Deferred revenue			0	53,800
Revenue allocated to other deliverables			53,800	170,000
Ebola costs revenue recognition			$ 761,500	$ 1,200,000

Stockholders' Equity (Details) - shares	12 Months Ended
Stockholders' Equity (Details) - shares	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Votes per share	1
Blank check preferred stock, outstanding shares	0	0
Blank check preferred stock, authorized shares	5,000,000	5,000,000

Common Stock Equity Incentive Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands										12 Months Ended
	Jan. 01, 2018	Jan. 01, 2017	Jan. 01, 2016	Jan. 01, 2015	Jan. 01, 2014	May 09, 2013	Jan. 01, 2013	Jan. 07, 2011	May 15, 2010	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 10, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense										$ 18,500	$ 16,700	$ 15,900
Total compensation cost related to non-vested option awards										18,000
Tax benefit from share-based compensation										$ 16,600	13,700	$ 7,800
Award vesting percentage										25.00%
Award vesting period										36 months
Intrinsic value of stock options (in dollars per share)										$ 8.11
Intrinsic value of stock options outstanding										$ 11,600
Intrinsic value of vested stock options										11,600
Intrinsic value of nonvested stock options										$ 6
Fair value of awards vested - accelerated compensation cost											$ 2,800
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Vesting Period for Non-vested Option Awards, In Years										2 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Vesting Period for Non-vested Option Awards, In Years										1 year 7 months 6 days
Granted (in shares)										0	193,834
Total unrecognized compensation cost										$ 3,700
Fair value of vested awards										$ 932
2009 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized										10,238,220	9,071,674
Number of shares available for grant										1,195,358	1,044,717
Number of authorized shares added		1,166,546	1,152,565	1,119,255	1,066,340		838,375	714,286	1,238,095
Evergreen increase										4.00%
2009 Equity Incentive Plan \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of authorized shares added	1,484,382
2009 Equity Incentive Plan \| Employee Stock Option \| First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage										25.00%
2009 Equity Incentive Plan \| Employee Stock Option \| Thereafter
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period										36 months
2010 Non-Employee Directors' Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized													238,095
Number of shares available for grant										0
Number of authorized shares added						161,905
2010 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized													214,285
Number of shares available for grant										101,996
Number of authorized shares added						185,715
Shares issued										70,787	58,609

Common Stock Equity Incentive Plans (Authorized Increases of Common Stock) (Details) - shares	Jan. 01, 2017	Jan. 01, 2016	Jan. 01, 2015	Jan. 01, 2014	Jan. 01, 2013	Jan. 07, 2011	May 15, 2010
2009 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized Shares Added	1,166,546	1,152,565	1,119,255	1,066,340	838,375	714,286	1,238,095

Common Stock Equity Incentive Plans (Stock Option Activity) (Details) - Employee Stock Option - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of options
Outstanding at beginning of period	6,278,542
Options granted (in shares)	1,526,787	1,346,758	1,019,445
Options exercised (in shares)	(120,716)
Options forfeited (in shares)	(324,947)
Options expired (in shares)	(157,445)
Outstanding at end of period	7,202,221	6,278,542
Weighted average exercise price
Outstanding at beginning of period, weighted average exercise price (in dollars per share)	$ 14.93
Options granted, weighted average exercise price (in dollars per share)	11.61
Options exercised, weighted average exercise price (in dollars per share)	7.96
Options forfeited, weighted average exercise price (in dollars per share)	19.88
Options expired, weighted average exercise price (in dollars per share)	33.27
Outstanding at end of period, weighted average exercise price (in dollars per share)	$ 13.72	$ 14.93
Options exercisable at end of period (in shares)	5,489,349
Exercisable, weighted average exercise price (in dollars per share)	$ 12.51
Outstanding, weighted average remaining contractual term, in years	5 years 3 months 18 days
Exercisable, weighted average remaining contractual term, in years	4 years 3 months 18 days

Common Stock Equity Incentive Plans (Range of Assumptions Used) (Details) - Employee Stock Option - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted (in shares)	1,526,787	1,346,758	1,019,445
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate, minimum	1.91%	1.19%	1.51%
Risk-free interest rate, maximum	2.22%	1.97%	2.00%
Weighted average grant-date fair value per share (in dollars per share)	$ 7.72	$ 11.91	$ 26.36
Volatility Rate, Minimum	68.90%	67.10%	62.50%
Volatility Rate, Maximum	76.88%	69.80%	67.30%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Term	1 year 2 months 12 days	5 years 10 months 24 days	5 years 10 months 24 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Term	7 years 9 months 18 days	7 years 4 months 25 days	7 years

Common Stock Equity Incentive Plans (Intrinsic Value of Options Exercised) (Details) - Employee Stock Option - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised	$ 1.0	$ 1.1	$ 16.7
Fair value of awards vested	$ 15.0	$ 15.1	$ 9.6

Common Stock Equity Incentive Plans (Restricted Stock Activity) (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock
Unvested at beginning of period (in shares)	288,964
Granted (in shares)	0	193,834
Vested (in shares)	(92,245)
Forfeited/cancelled (in shares)	(28,498)
Unvested at end of period (in shares)	168,221	288,964
Weighted Average Grant Date Fair Value
Beginning of period, weighted average grant date fair value (in dollars per share)	$ 34.94
Granted, weighted average grant date fair value (in dollars per share)	0.00
Vested, weighted average grant date fair value (in dollars per share)	33.70
Forfeited/cancelled, weighted average grant date fair value (in dollars per share)	33.72
End of period, weighted average grant date fair value (in dollars per share)	$ 35.82	$ 34.94

Income Taxes Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
Income Taxes Narrative (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Income tax benefit from impact of the Tax Act		$ 140,000
Deferred Tax Valuation Allowance	$ (35,122,000)	(50,198,000)	$ (35,122,000)
Net change total valuation allowance		15,100,000	14,400,000
Income tax benefit (expense)	640,000	559,000	5,356,000	$ (6,738,000)
Income tax interest and penalties	$ 0	335,000	$ 0	$ 0
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		38,800,000
Domestic Tax Authority \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		$ 26,200,000

Income Taxes Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
U.S. federal		$ 332	$ 6,469	$ (5,522)
State and local		87	(1,113)	(1,216)
Current income tax expense		419	5,356	(6,738)
Deferred
U.S. federal		140	0	0
State and local		0	0	0
Deferred income tax expense		140	0	0
U.S. federal		472	6,469	(5,522)
State and local		87	(1,113)	(1,216)
Income tax benefit (expense)	$ 640	$ 559	$ 5,356	$ (6,738)

Income Taxes Deferred Tax (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 10,622	$ 654
Federal research and development tax credits	26,327	20,836
Share-based compensation	11,780	11,843
Deferred rent	327	491
Minimum tax credits	0	143
Accrued compensation	789	427
Unearned revenue	17	163
Charitable contributions	39	13
Leasehold improvements and equipment	297	552
Gross deferred tax assets	50,198	35,122
Less valuation allowance	50,198	35,122
Total deferred tax assets	$ 0	$ 0

Income Taxes Income Tax Rate Reconciliation (Details)	12 Months Ended
Income Taxes Income Tax Rate Reconciliation (Details)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. federal income tax expense (benefit) at the statutory rate	(35.00%)	(35.00%)	(35.00%)
Available research and experimentation tax credits	0.00%	0.00%	(2.30%)
State income taxes, net of federal taxes	(0.03%)	0.88%	(0.50%)
Loss in foreign subsidiary	7.36%	15.88%	43.60%
Valuation allowance, including impact of tax reform	24.10%	12.07%	13.70%
Other	2.80%	0.25%	0.50%
Total	(0.77%)	(5.92%)	20.00%

Income Taxes Uncertain Income Tax Positions (Details)	12 Months Ended
Income Taxes Uncertain Income Tax Positions (Details)	Dec. 31, 2017 USD ($)
Reconciliation of Uncertain Income Tax Positions
Beginning Balance - uncertain tax positions	$ 653,000
Increases for tax positions related to current year	0
Decreases due to settlements with taxing authorities	0
Reductions due to lapsed statute of limitations	0
Ending Balance - uncertain tax positions	$ 653,000

Loss Per Share (Net Loss Per Share Computation) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator
Net loss attributable to common stockholders	$ (13,686)	$ (20,626)	$ (16,726)	$ (20,913)	$ (13,506)	$ (15,540)	$ (32,389)	$ (23,720)	$ (71,951)	$ (85,155)	$ (40,381)
Denominator
Basic weighted-average shares outstanding (in shares)									31,304,309	28,979,327	28,586,585
Basic and diluted loss per share (in dollars per share)									$ (2.30)	$ (2.94)	$ (1.41)

Loss Per Share (Antidilutive Securities) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share
Potentially dilutive securities excluded from computation of diluted net loss per share	7,202,221	6,278,542
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Potentially dilutive securities excluded from computation of diluted net loss per share	168,221	288,964

Licensing Agreements (Details) $ in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2017 CAD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Licensing Agreements
Licensing payments under agreements		$ 1.4	$ 2.0	$ 2.0
Augusta University Research Institute under AURI IDO
Licensing Agreements
Aggregate potential milestone payment per licensed product		2.8
Augusta University Research Institute under AURI PTEN
Licensing Agreements
Licensing payments under agreements		$ 4.3
Public Health Agency of Canada
Licensing Agreements
Aggregate potential milestone payment per licensed product	$ 475

Employee Benefit Plans (Details) - USD ($)	12 Months Ended
Employee Benefit Plans (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined contributions	$ 361,000	$ 482,000	$ 361,000
Discretionary contributions	$ 401,000	$ 446,000	$ 319,000
Minimum
Defined Benefit Plan Disclosure [Line Items]
Duration of payments	6 months
Maximum
Defined Benefit Plan Disclosure [Line Items]
Duration of payments	24 months

Restructuring Charges (Details) - USD ($)	1 Months Ended	12 Months Ended
Restructuring Charges (Details) - USD ($)	Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Percentage reduction in force	50.00%
Asset impairment charges			$ 4,000,000
Restructuring Reserve [Roll Forward]
Beginning balance		$ 42,000
Expensed		1,735,000	11,600,000
Cash Payments		1,570,000
Adjustments		0
Ending balance		207,000	42,000
Employee Severance
Restructuring Reserve [Roll Forward]
Beginning balance		42,000
Expensed		1,735,000
Cash Payments		1,570,000
Adjustments		0
Ending balance		207,000	42,000
General and Administrative Expense
Restructuring Reserve [Roll Forward]
Expensed		1,100,000	500,000
Research and Development Expense
Restructuring Reserve [Roll Forward]
Expensed		$ 600,000	$ 11,100,000

Quarterly Financial Information (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Grant and licensing revenue	$ 10,098,000	$ 5,482,000	$ 10,370,000	$ 2,761,000	$ 12,703,000	$ 15,345,000	$ 2,012,000	$ 5,708,000	$ 28,700,000	$ 35,800,000	$ 68,500,000
Loss from operations	(14,051,000)	(20,905,000)	(16,727,000)	(21,198,000)	(13,970,000)	(16,687,000)	(34,528,000)	(25,393,000)	(72,881,000)	(90,758,000)	(33,602,000)
Net loss	$ (13,686,000)	$ (20,626,000)	$ (16,726,000)	$ (20,913,000)	$ (13,506,000)	$ (15,540,000)	$ (32,389,000)	$ (23,720,000)	(71,951,000)	(85,155,000)	(40,381,000)
Basic and diluted loss per share (in dollars per share)	$ (0.37)	$ (0.69)	$ (0.57)	$ (0.72)	$ (0.46)	$ (0.54)	$ (1.12)	$ (0.82)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact on income tax						$ 513,000	$ 127,000
Income tax expense					$ 640,000				$ 559,000	$ 5,356,000	$ (6,738,000)
Additional Paid-in Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense					$ (640,000)
Accounting Standards Update 2016-09 \| Additional Paid-in Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle		$ 513,000	$ 127,000