Endocyte (ECYT) 10-K 13 Mar 17 2016 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Feb. 28, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Entity Registrant Name	ENDOCYTE INC
Entity Central Index Key	1,235,007
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 120.7
Entity Common Stock, Shares Outstanding		42,470,874

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 31,228,192	$ 15,431,622
Short-term investments	106,979,224	158,168,832
Receivables	55,074	8,678
Prepaid expenses	1,737,308	772,579
Other assets	255,912	493,863
Total current assets	140,255,710	174,875,574
Property and equipment, net	3,205,077	3,398,398
Other noncurrent assets	33,567	111,605
Total assets	143,494,354	178,385,577
Current liabilities:
Accounts payable	1,381,545	1,262,565
Accrued wages and benefits	2,705,475	3,272,237
Accrued clinical trial expenses	861,293	804,066
Accrued expenses and other liabilities	613,861	850,125
Total current liabilities	5,562,174	6,188,993
Other liabilities, net of current portion	2,873	18,503
Deferred revenue, net of current portion	781,944	831,944
Total liabilities	6,346,991	7,039,440
Stockholders’ equity:
Common stock: $0.001 par value, 100,000,000 shares authorized; 42,034,733 and 42,377,522 shares issued and outstanding at December 31, 2015 and December 31, 2016	42,378	42,035
Additional paid-in capital	390,768,742	381,118,489
Accumulated other comprehensive (loss) income	(41,196)	(79,399)
Retained deficit	(253,622,561)	(209,734,988)
Total stockholders’ equity	137,147,363	171,346,137
Total liabilities and stockholders’ equity	$ 143,494,354	$ 178,385,577

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	42,377,522	42,034,733
Common stock, shares outstanding	42,377,522	42,034,733

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Collaboration revenue	$ 70,000	$ 70,000	$ 70,353,483
Total revenue	70,000	70,000	70,353,483
Operating expenses:
Research and development	27,492,185	26,309,475	41,649,389
General and administrative	17,298,139	15,733,462	23,677,366
Total operating expenses	44,790,324	42,042,937	65,326,755
Loss from operations	(44,720,324)	(41,972,937)	5,026,728
Other income (expense), net:
Interest income, net	861,212	651,543	577,447
Other income (expense), net	(28,461)	51,645	(144,698)
Net income (loss)	$ (43,887,573)	$ (41,269,749)	$ 5,459,477
Net income (loss) per share - basic (in dollars per share)	$ (1.04)	$ (0.98)	$ 0.14
Net income (loss) per share - diluted (in dollars per share)	$ (1.04)	$ (0.98)	$ 0.13
Items included in other comprehensive income (loss):
Unrealized gain (loss) on foreign currency translation		$ 50,592	$ (38,776)
Unrealized gain (loss) and amounts reclassified to net loss on available-for-sale securities	$ 38,203	13,937	(161,843)
Other comprehensive income (loss)	38,203	64,529	(200,619)
Comprehensive income (loss)	$ (43,849,370)	$ (41,205,220)	$ 5,258,858
Weighted-average number of common shares used in net income (loss) per share calculation - basic (in shares)	42,210,643	41,939,504	40,242,352
Weighted-average number of common shares used in net income (loss) per share calculation - diluted (in shares)	42,210,643	41,939,504	41,758,101

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss)	Retained Earnings [Member]	Total
Balance at beginning of period at Dec. 31, 2013	$ 36,156	$ 262,060,590	$ 56,691	$ (173,924,716)	$ 88,228,721
Balances (in shares) at Dec. 31, 2013	36,155,509
Exercise of stock options	$ 400	1,290,486	0	0	$ 1,290,886
Exercise of stock options (in shares)	399,654				399,654
Stock-based compensation	$ 1	8,021,446			$ 8,021,447
Stock-based compensation (in shares)	1,279
Employee stock purchase plan	$ 53	299,176	0	0	299,229
Issuance of common stock in connection with secondary offering	$ 5,175	101,899,802			101,904,977
Issuance of common stock in connection with secondary offering (in shares)	5,175,000
Number of shares purchased under ESPP	53,250
Net income (loss)	$ 0	0	0	5,459,477	5,459,477
Unrealized loss on foreign currency translation	0	0	(38,776)	0	(38,776)
Unrealized loss on securities	0	0	(161,843)	0	(161,843)
Balance at end of period at Dec. 31, 2014	$ 41,785	373,571,500	(143,928)	(168,465,239)	205,004,118
Balances (in shares) at Dec. 31, 2014	41,784,692
Exercise of stock options	$ 146	379,144	0	0	$ 379,290
Exercise of stock options (in shares)	146,046				146,046
Stock-based compensation	$ 29	6,862,917	0	0	$ 6,862,946
Stock-based compensation (in shares)	29,190
Employee stock purchase plan	$ 75	304,928	0	0	305,003
Number of shares purchased under ESPP	74,805
Net income (loss)	$ 0	0	0	(41,269,749)	(41,269,749)
Unrealized loss on foreign currency translation	0	0	50,592	0	50,592
Unrealized loss on securities	0	0	13,937	0	13,937
Balance at end of period at Dec. 31, 2015	$ 42,035	381,118,489	(79,399)	(209,734,988)	171,346,137
Balances (in shares) at Dec. 31, 2015	42,034,733
Exercise of stock options	$ 130	260,952			$ 261,082
Exercise of stock options (in shares)	129,638				129,638
Stock-based compensation	$ 127	9,157,528			$ 9,157,655
Stock-based compensation (in shares)	126,580
Employee stock purchase plan	$ 86	231,773			231,859
Number of shares purchased under ESPP	86,571
Net income (loss)				(43,887,573)	(43,887,573)
Unrealized loss on securities	$ 0	0	38,203	0	38,203
Balance at end of period at Dec. 31, 2016	$ 42,378	$ 390,768,742	$ (41,196)	$ (253,622,561)	$ 137,147,363
Balances (in shares) at Dec. 31, 2016	42,377,522

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income (loss)	$ (43,887,573)	$ (41,269,749)	$ 5,459,477
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	919,809	886,710	857,055
Stock-based compensation	9,322,127	6,920,220	8,025,261
Loss on disposal of property and equipment	0	10,639	6,100
Accretion of bond premium	395,116	1,310,238	1,615,063
Net realized foreign currency translation loss	0	51,944	0
Change in operating assets and liabilities:
Receivables	191,555	856,372	5,490,605
Prepaid expenses and other assets	(517,318)	(96,582)	2,711,331
Accounts payable	(252,605)	(60,713)	(3,700,175)
Accrued wages, benefits and other liabilities	(771,866)	(777,204)	(2,923,537)
Deferred revenue	(50,000)	(50,000)	(59,746,948)
Net cash used in operating activities	(34,650,755)	(32,218,125)	(42,205,768)
Investing activities
Purchases of property and equipment	(713,839)	(341,616)	(1,501,744)
Proceeds from disposal of property and equipment	0	0	10,000
Purchases of investments	(139,932,358)	(86,281,946)	(149,370,678)
Proceeds from sale and maturities of investments	190,765,053	88,114,199	82,302,191
Net cash provided by investing activities	50,118,856	1,490,637	(68,560,231)
Financing activities
Stock repurchase	(164,472)	(57,274)	(3,814)
Proceeds from public offering	0	0	101,904,977
Proceeds from the exercise of stock options	261,082	379,290	1,290,886
Proceeds from stock purchases under employee stock purchase plan	231,859	305,003	299,229
Net cash provided by financing activities	328,469	627,019	103,491,278
Effect of exchange rate	0	(1,352)	(38,776)
Net increase (decrease) in cash and cash equivalents	15,796,570	(30,101,821)	(7,313,497)
Cash and cash equivalents at beginning of period	15,431,622	45,533,443	52,846,940
Cash and cash equivalents at end of period	$ 31,228,192	$ 15,431,622	$ 45,533,443

Nature of Business and Organiza

Nature of Business and Organization	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1. Nature of Business and Organiz Endocyte, Inc. (the “Company”) is a biopharmaceutical company developing targeted therapies for the treatment of cancer and inflammatory diseases. The Company uses its proprietary technology to create novel small molecule drug conjugates (“SMDCs”), and companion imaging agents. The SMDCs actively target receptors that are over-expressed on diseased cells, relative to healthy cells. This targeted approach is designed to enable the treatment of patients with a highly active drug at greater doses, delivered more frequently, and over longer periods of time than would be possible with the untargeted drug alone. The Company is also developing companion imaging agents for each of its SMDCs that are designed to identify the patients whose disease over-expresses the target of the therapy and who are therefore most likely to benefit from treatment. The Company had two wholly-owned subsidiaries, Endocyte Europe B.V. and Endocyte Europe GmbH, which were formed to assist with the administration of applications with the European Commission (“EC”) and commercial pre-launch activities in Europe. The applications were withdrawn in May 2014 and the commercial pre-launch activities in Europe ceased. The Company dissolved Endocyte Europe GmbH in the fourth quarter of 2015 and dissolved Endocyte Europe B.V. in the first quarter of 2016. Public Offerings On April 2, 2014, the Company completed a public offering of 5,175,000 shares of its common stock in a public offering. Proceeds, net of underwriting discounts, commissions and other transaction costs, were $101.9 million.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	2. Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include the accounts of Endocyte, Inc. and its subsidiaries and all intercompany amounts have been eliminated as of December 31, 2014 and 2015. The accompanying financial statements for the year ended December 31, 2016 include only the accounts of Endocyte, Inc. as the Company dissolved Endocyte Europe GmbH and Endocyte Europe B.V. in the fourth quarter of 2015 and the first quarter of 2016, respectively. There were no intercompany transactions in the year ended December 31, 2016 and no intercompany balances as of December 31, 2016. The consolidated financial statements are prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). Subsequent events have been evaluated through the date of issuance, which is the same as the date this Form 10-K is filed with the Securities and Exchange Commission. Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual amounts may differ from those estimates. Cash and Cash Equivalents The Company considers cash and all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents consist primarily of FDIC insured deposits with multiple banks and money market instruments that are maintained by an investment manager. Investments Investments consist primarily of investments in U.S. Treasuries, U.S. Government agency obligations and corporate debt securities, which could also include commercial paper, that are maintained by an investment manager. U.S. government agency investments relate to investments in Fannie Mae, Freddie Mac and Federal Home Loan Bank. Management determines the appropriate classification of marketable securities at the time of purchase and reevaluates such classification as of each balance sheet date. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities are included in other income. The Company considers and accounts for other-than-temporary impairments according to the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 320, Investments — Debt and Equity Securities (“ASC 320”). The cost of securities sold is based on the specific-identification method. Discounts and premiums on debt securities are amortized to interest income and expense over the term of the security. Property and Equipment Property and equipment are stated at cost and are being depreciated using the straight-line method over estimated useful lives, which range from three to seven years. Licenses and Patents Licenses and patent costs are expensed as incurred as the Company does not believe there is an alternate future use for the costs. Licenses are classified as research and development expenses and patents are classified as general and administrative expenses in the consolidated statements of operations. Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment when events or changes in business conditions indicate that their full carrying value may not be fully recoverable. Leases The Company evaluates all leases to determine whether they should be accounted for as operating or capital leases. Revenue Recognition The Company recognizes revenues from license and collaboration agreements when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the fee is fixed or determinable, and there is reasonable assurance that the related amounts are collectible in accordance with ASC Topic 605, Revenue Recognition (“ASC 605”). The Company’s license and collaboration agreements may contain multiple elements, including grants of licenses to intellectual property rights, agreement to provide research and development services and other deliverables. The deliverables under such arrangements are evaluated under ASC Subtopic 605-25, Multiple-Element Arrangements (“ASC 605-25”). Under ASC 605-25, each required deliverable is evaluated to determine whether it qualifies as a separate unit of accounting based on whether the deliverable has “stand-alone value” to the customer. The arrangement’s consideration that is fixed or determinable, excluding contingent milestone payments, is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. In general, the consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. Upfront payments for licensing the Company’s intellectual property are evaluated to determine if the licensee can obtain stand-alone value from the license separate from the value of the research and development services and other deliverables in the arrangement to be provided by the Company. If at the inception of an arrangement the Company determines that the license does not have stand-alone value separate from the research and development services or other deliverables, the license, services and other deliverables are combined as one unit of account and upfront payments are recorded as deferred revenue on the balance sheet and are recognized in a manner consistent with the final deliverable. Subsequent to the inception of an arrangement, the Company evaluates the remaining deliverables for separation as items in the arrangement are delivered. When stand-alone value is identified, the related consideration is recorded as revenue in the period in which the license or other intellectual property rights are delivered. In those circumstances where research and development services or other deliverables are combined with the license, and multiple services are being performed such that a common output measure to determine a pattern of performance cannot be discerned, the Company recognizes amounts received on a straight line basis over the performance period. Such amounts are recorded as collaboration revenue. Any subsequent reimbursement payments, which are contingent upon the Company’s future research and development expenditures, will be recorded as collaboration revenue and will be recognized on a straight-line basis over the performance period using the cumulative catch up method. The costs associated with these activities are reflected as a component of research and development expense in the statements of operations in the period incurred. In the event of an early termination of a collaboration agreement, any deferred revenue is recognized in the period in which all obligations of the Company under the agreement have been fulfilled. Milestone payments under collaborative arrangements are triggered either by the results of the Company’s research and development efforts, achievement of regulatory goals or by specified sales results by a third-party collaborator. Milestones related to the Company’s development-based activities may include initiation of various phases of clinical trials and applications and acceptance for product approvals by regulatory agencies. Due to the uncertainty involved in meeting these development-based milestones, the determination is made at the inception of the collaboration agreement whether the development-based milestones are considered to be substantive (i.e. not just achieved through passage of time). In addition, the amounts of the payments assigned thereto are considered to be commensurate with the enhancement of the value of the delivered intellectual property as a result of the Company’s performance. Because the Company’s involvement is necessary to the achievement of development-based milestones, the Company would account for development-based milestones as revenue upon achievement of the substantive milestone events. Milestones related to sales-based activities may be triggered upon events such as first commercial sale of a product or when sales first achieve a defined level. Since these sales-based milestones would be achieved after the completion of the Company’s development activities, the Company would account for the sales-based milestones in the same manner as royalties, with revenue recognized upon achievement of the milestone. Royalties based on reported sales of licensed products will be recognized based on contract terms when reported sales are reliably measurable and collectability is reasonably assured. To date, none of the Company’s products have been approved and therefore the Company has not earned any royalty revenue from product sales. In territories where the Company and a collaborator may share profit, the revenue would be recorded in the period earned. The Company often is required to make estimates regarding drug development and commercialization timelines for compounds being developed pursuant to a collaboration agreement. Because the drug development process is lengthy and the Company’s collaboration agreements typically cover activities over several years, this approach often results in the deferral of significant amounts of revenue into future periods. In addition, because of the many risks and uncertainties associated with the development of drug candidates, the Company’s estimates regarding the period of performance may change in the future. Any change in the Company’s estimates or a termination of the arrangement could result in substantial changes to the period over which the revenues are recognized. Research and Development Expenses Research and development expenses represent costs associated with the ongoing development of SMDCs and companion imaging agents and include salaries and employee benefits, supplies, facility costs related to research activities, and expenses for clinical trials. The Company records accruals for clinical trial expenses based on the estimated amount of work completed. The Company monitors patient enrollment levels and related activities to the extent possible through internal reviews, correspondence, and discussions with research organizations. In the event that a clinical trial is terminated early, the Company records, in the period of termination, an accrual for the estimated remaining costs to complete the trial. Upfront payments made in connection with business collaborations and research and development arrangements are evaluated under ASC Subtopic 730-20, Research and Development Arrangements . Upfront payments made in connection with business development collaborations are expensed as research and development costs, as the assets acquired do not have alternative future use. Amounts related to future research and development are capitalized as prepaid research and development and are expensed over the service period based upon the level of services provided. As of December 31, 2016, the Company had approximately $1.0 million of capitalized research and development costs included in prepaid expenses. Stock-Based Compensation The Company accounts for its stock-based compensation pursuant to ASC Topic 718, Compensation — Stock Compensation (“ASC 718”), which requires the recognition of the fair value, or calculated value for nonpublic entities, of stock-based compensation in net income. Stock-based compensation consists of stock options, which are granted at exercise prices at or above the fair market value of the Company’s common stock on the dates of grant, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), and shares available for purchase under the Company’s 2010 Employee Stock Purchase Plan (“ESPP”). For PRSUs issued by the Company, stock-based compensation expense would be recognized if and when the Company determines that it is probable that the performance conditions will be achieved. For RSUs issued by the Company, stock-based compensation expense is recognized ratably over the service period. The Company recognizes compensation cost based on the grant-date fair value estimated in accordance with the provisions of ASC 718. Net Income (Loss) Per Share The Company calculates basic net income (loss) per share based on the weighted-average number of outstanding common shares. The Company calculates diluted net income (loss) per share based on the weighted-average number of outstanding common shares plus the effect of dilutive securities. Income Taxes The Company accounts for income taxes under the liability method in accordance with the provision of ASC Topic 740, Income Taxes (“ASC 740”). ASC 740 requires recognition of deferred taxes to provide for temporary differences between financial reporting and tax basis of assets and liabilities. Deferred taxes are measured using enacted tax rates expected to be in effect in a year in which the basis difference is expected to reverse. The Company continues to record a valuation allowance for the full amount of deferred tax assets, which would otherwise be recorded for tax benefits relating to operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not. The Company accounts for uncertain income tax positions recognized in the financial statements in accordance with Accounting Standards Update (“ASU”) No. 2009-06. This guidance prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return and provides guidance on derecognition of tax benefits, classification on the balance sheet, interest and penalties, accounting in interim periods, disclosure, and transition. Segment Information Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company had performed clinical trials globally and established a subsidiary in The Netherlands to assist in the administration of filing applications in Europe and a subsidiary in Switzerland for commercial pre-launch activities in Europe. The applications filed in Europe were withdrawn in May 2014 and the pre-launch activities in Europe ceased. The Company dissolved Endocyte Europe GmbH in the fourth quarter of 2015 and dissolved Endocyte Europe B.V. in the first quarter of 2016. All long-lived assets are held in the U.S. The Company views its operations and manages its business in one operating segment.

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2016
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Standards	3. New Accounting Pronouncements Recently Issued Accounting Standards In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , an update to ASC 718. This guidance involves improving several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, classification on the statement of cash flows, and the forfeiture rate calculation. This update is effective for the Company for interim and annual reporting periods beginning January 1, 2017. The Company does not expect the adoption of this guidance to have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases , an update to ASC Topic 842, Leases . This guidance requires lessees to recognize leases as assets and liabilities on their balance sheets but recognize expenses on their income statements in a manner similar to the current accounting guidance. For lessors, the guidance also modifies the classification criteria and the accounting for sales-type and direct finance leases. This update is effective for the Company for interim and annual reporting periods beginning January 1, 2019 unless it elects early adoption. The Company is currently evaluating the impact, if any, the adoption of this guidance will have on its consolidated financial statements. In August 2014, the FASB issued ASU 2014-15 (Subtopic 205-40), Presentation of Financial Statements — Going Concern , which requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and provide related footnote disclosures. This guidance is effective for the Company for interim and annual reporting periods beginning on or after December 15, 2016. The standard allows for either a full retrospective or modified retrospective transition method. For the year ended December 31, 2016, the Company evaluated its ability to continue as a going concern and noted no substantial doubt or disclosures necessary. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), to clarify the principles used to recognize revenue for all entities. Under ASU 2014-09, an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In order to do so, an entity would follow the five-step process for in-scope transactions: 1) identify the contract with a customer, 2) identify the separate performance obligations in the contract, 3) determine the transaction price, 4) allocate the transaction price to the separate performance obligations in the contract, and 5) recognize revenue when (or as) the entity satisfies a performance obligation. In August 2015, the FASB issued ASU 2015-14, which defers the effective date of ASU 2014-09 by one year. Therefore, ASU 2014-09 will become effective for the Company for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted, but not any earlier than the original effective date of December 15, 2016. An entity can apply the new revenue standard retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. In April 2016, the FASB issued ASU 2016-10, an update to Topic 606, which clarifies how entities should identify performance obligations and evaluate licensing. In May 2016, the FASB issued ASU 2016-12, an update to Topic 606, which clarifies guidance on transition, collectability, noncash consideration and the presentation of sales and other similar taxes. In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which affects narrow aspects of the guidance issued in ASU 2014-09. The Company is currently evaluating the impact, if any, the adoption of this guidance will have on its consolidated financial statements.

Net Income (Loss) per Share

Net Income (Loss) per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	4. Net Income (Loss) per Share Basic net income (loss) per share is calculated by dividing the net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net income (loss) per share is computed by dividing the net income (loss) attributable to common stockholders by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method and the if-converted method. For purposes of this calculation, stock options, warrants, PRSUs, RSUs and shares to be purchased under the Company’s 2010 ESPP are considered to be common stock equivalents and are only included in the calculation of diluted net income (loss) per share when their effect is dilutive. As of December 31, 2014, 2015 and 2016, the following number of potential common stock equivalents were outstanding: Common stock equivalents Year Ended December 31, 2014 2015 2016 Outstanding common stock options Outstanding warrants Outstanding PRSUs — Outstanding RSUs Shares to be purchased under the ESPP Total These common stock equivalents were excluded from the determination of diluted net loss per share for the years ended December 31, 2015 and December 31, 2016, due to their anti-dilutive effect on earnings. The following weighted-average outstanding common stock options, warrants, RSUs and shares to be purchased under the ESPP were added to basic weighted-average common shares outstanding for the year ended December 31, 2014 to calculate diluted weighted-average shares outstanding because of their dilutive effect: Year Ended December 31, 2014 Outstanding common stock options Outstanding warrants Outstanding RSUs Shares to be purchased under the ESPP Total

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Other Comprehensive Income (Loss) [Text Block]	5. Other Comprehensive Income (Loss) The accumulated balances related to each component of other comprehensive income (loss) were as follows: Foreign Accumulated Currency Unrealized Net Other Translation Gains (Losses) Comprehensive Gains (Losses) on Securities Gains (Losses) Balance at December 31, 2013 $ $ $ Unrealized loss Net amount reclassified to net income — Other comprehensive loss Balance at December 31, 2014 $ $ $ Unrealized gain (loss) Net amount reclassified to net loss Other comprehensive income Balance at December 31, 2015 $ — $ $ Unrealized gain — Net amount reclassified to net loss — Other comprehensive income — Balance at December 31, 2016 $ — $ $ The assets and liabilities of foreign operations were translated into U.S. dollars using the current exchange rate. For those operations, changes in exchange rates generally did not affect cash flows, which resulted in translation adjustments made in stockholders’ equity rather than to net income (loss). The accumulated balance of translation adjustments for Endocyte Europe B.V. were reclassified out of accumulated other comprehensive income (loss) and recognized as foreign currency translation losses reported in other income (expense) as the Company determined that the liquidation of Endocyte Europe B.V. was substantially complete as of December 31, 2015. There were no transactions from foreign operations in the year ended December 31, 2016. Reclassifications Out of Accumulated Other Comprehensive Income (Loss) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Year Ended Year Ended Year Ended Consolidated Details about Accumulated Other December 31, December 31, December 31, Statements of Operations and Comprehensive Income (Loss) Components 2014 2015 2016 Comprehensive Income (Loss) Unrealized Net Gains (Losses) on Securities $ $ $ Other income (expense) Foreign Currency Translation Losses — — Other income (expense) Total Reclassifications for the Period $ $ $

Investments

Investments	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]	6. Investments The Company applies the fair value measurement and disclosure provisions of ASC Topic 820, Fair Value Measurements and Disclosures (“ASC 820”). ASC 820, which defines fair value, establishes a framework for measuring fair value in GAAP, and expands disclosures about fair value measurements. Investments consist primarily of investments with original maturities greater than three months, but no longer than 24 months when purchased. ASC 820 establishes a three-level valuation hierarchy for fair value measurements. These valuation techniques are based upon the transparency of inputs (observable and unobservable) to the valuation of an asset or liability as of the measurement date. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions. These two types of inputs create the following fair value hierarchy: Level 1 — Valuation is based on quoted prices for identical assets or liabilities in active markets. Level 2 — Valuation is based on quoted prices for similar assets or liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for the full term of the financial instrument. Level 3 — Valuation is based upon other unobservable inputs that are significant to the fair value measurement. The fair value of the Company’s fixed income securities is based on a market approach using quoted market values. The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2015: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ $ $ — $ Cash equivalents FDIC insured deposits and money market funds — Cash and cash equivalents $ $ $ — $ Short-term investments (due within 1 year) U.S. government treasury obligations $ $ $ — $ U.S. government agency obligations — Corporate obligations — Total short-term investments $ $ $ $ The following table summarizes the fair value of cash and cash equivalents and investments as of December: 31, 2016: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ $ $ — $ Cash equivalents FDIC insured deposits and money market funds — Cash and cash equivalents $ $ $ — $ Short-term investments (due within 1 year) U.S. government treasury obligations $ $ $ — $ Corporate obligations — Total short-term investments $ $ $ $ All securities held at December 31, 2015 and 2016, were classified as available-for-sale as defined by ASC 320. Total unrealized gross gains were $5,690 and $8,257 for the years ended December 31, 2015 and 2016, respectively. Total unrealized gross losses were $85,089 and $49,453 for the years ended December 31, 2015 and 2016, respectively. The Company does not consider any of the unrealized losses to be other-than-temporary impairments because the Company has the intent and ability to hold investments until they recover in value. Total realized gross gains were $1,667 for the year ended December 31, 2015. There were no total realized gross gains for the year ended December 31, 2016. Total realized gross losses were $53 for the year ended December 31, 2016. There were no total realized gross losses for the year ended December 31, 2015.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	7. Property and Equipment Property and equipment consisted of the following: Estimated December 31, Useful Lives 2015 2016 Laboratory equipment 7 $ $ Office equipment and software 3 – 7 Leasehold improvements 7 Assets not in service Less accumulated depreciation $ $ Assets not in service represent new laboratory equipment, computer equipment and software that were not installed and ready to use at December 31, 2015 and 2016. The total amount of depreciation expense for the years ended December 31, 2014, 2015 and 2016 were $857,055, $886,710 and $919,809, respectively.

Warrant

Warrant	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Warrant Disclosure [Text Block]	8. Warrant In 2007, the Company issued a warrant as consideration in connection with, among other things, its loan commitment from General Electric Capital Corporation to purchase Series C-3 convertible preferred stock, maturing on December 31, 2017. Upon closing of the initial public offering, this warrant was converted to a warrant to purchase 34,647 shares of common stock at an exercise price of $8.12 per share and was reclassified to stockholders’ equity. During 2015, General Electric Capital Corporation transferred its outstanding warrant to Healthcare Equity Holdings, LLC.

Leases

Leases	12 Months Ended
	Dec. 31, 2016
Leases [Abstract]
Leases of Lessee Disclosure [Text Block]	9. Leases Future minimum lease payments for noncancellable operating leases as of December 31, 2016, are as follows: 2017 $ 2018 2019 — 2020 — 2021 — Thereafter — Total minimum lease payments $ Rent expense for operating leases was $866,768, $736,249 and $743,323 for the years ended December 31, 2014, 2015 and 2016, respectively.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Stockholders' Equity Note Disclosure	10. Stockholders’ Equity Stock-Based Compensation Plans The Company has had stock-based compensation plans since 1997. The awards made under the plans adopted in 1997 and 2007 consisted of stock options. The 2010 Equity Incentive Plan (the “2010 Plan”), which is the only plan under which awards may currently be made, authorizes awards in the form of stock options, stock appreciation rights, restricted stock, RSUs, PRSUs, and performance units and performance shares. Awards under the 2010 Plan may be made to employees, directors and certain consultants as determined by the compensation committee of the board of directors. There were 9,742,563 and 11,003,563 shares of common stock authorized and reserved under these plans at December 31, 2015 and December 31, 2016, respectively. Stock Options Under the various plans, employees have been granted incentive stock options, while directors and consultants have been granted non-qualified options. The plans allow the holder of an option to purchase common stock at the exercise price, which was at or above the fair value of the Company’s common stock on the date of grant. Generally, options granted under the 1997 and 2007 plans in connection with an employee’s commencement of employment vest over a four-year period with one-half of the shares subject to the grant vesting after two years of employment and remaining options vesting monthly over the remainder of the four-year period. Options granted under the 1997 and 2007 plans for performance or promotions vest monthly over a four-year period. Generally, options granted under the 2010 Plan vest annually over a three-year or four-year period. Unexercised stock options terminate on the tenth anniversary date after the date of grant. The Company recognizes stock-based compensation expense over the requisite service period of the individual grantees, which generally equals the vesting period. The Company utilizes a Black-Scholes option-pricing model to estimate the value of stock options. The Black-Scholes model allows the use of a range of assumptions related to volatility, risk-free interest rate, employee exercise behavior and dividend yield. Expected volatilities used in the model beginning in 2015 are based on historical volatility of the Company’s stock prices. Expected volatilities used in the model prior to 2015 were based on a combination of peer volatility and Company volatility. The Company is using the “simplified” method for “plain vanilla” options to estimate the expected term of the stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option. The risk-free interest rate assumption is derived from the weighted-average yield of a U.S. Treasury security with the same term as the expected life of the options, and the dividend yield assumption is based on historical experience and the Company’s estimate of future dividend yields. The weighted-average value of the individual options granted during 2014, 2015 and 2016 were determined using the following assumptions: Year Ended December 31, 2014 2015 2016 Expected volatility % % % Risk-free interest rate % % % Weighted-average expected life (in years) Dividend yield % % % The resulting value of options granted was $4,884,534 and $2,838,053 for the years ended December 31, 2015 and 2016, respectively, which will be amortized into income over the remaining requisite service period. The Company executed a Separation Agreement and Release of Claims with its former Chief Executive Officer, P. Ron Ellis, in connection with his resignation from the Company in June 2016. Under this agreement and Mr. Ellis’ original Severance Agreement, the Company incurred additional stock compensation expense of $2,800,000 related to the modification of Mr. Ellis’ options and RSUs. The vesting of each stock option and RSU, other than fully vested awards, was modified and the exercise period of each stock option was extended. In determining the additional expense related to the modification of Mr. Ellis’ awards, the Company revalued the modified options in accordance with ASC 718 using the Black-Scholes model. The Company recognized total stock-based compensation cost, net of forfeitures, in the amount of $8,025,261, $6,920,220 and $9,322,127 for the years ended December 31, 2014, 2015 and 2016, respectively. The Company’s stock option activity and related information are summarized as follows: Weighted-Average Remaining Weighted-Average Contractual Term Aggregate Options Exercise Price (In Years) Intrinsic Value Outstanding at January 1, 2014 $ Granted during year Exercised during year Expired during year Forfeited during year Outstanding at December 31, 2014 $ $ Exercisable at December 31, 2014 Outstanding at January 1, 2015 Granted during year Exercised during year Expired during year Forfeited during year Outstanding at December 31, 2015 $ $ Exercisable at December 31, 2015 Outstanding at January 1, 2016 Granted during year Exercised during year Expired during year Forfeited during year Outstanding at December 31, 2016 $ $ Exercisable at December 31, 2016 The following is a rollforward of the Company’s nonvested stock options from January 1, 2014 to December 31, 2016. Weighted-Average Options Grant Date Value Nonvested stock options at January 1, 2014 $ Granted during year Vested during year Forfeited during year Nonvested at December 31, 2014 $ Nonvested stock options at January 1, 2015 $ Granted during year Vested during year Forfeited during year Nonvested at December 31, 2015 $ Nonvested stock options at January 1, 2016 $ Granted during year Vested during year Forfeited during year Nonvested at December 31, 2016 $ The total grant date value of stock options vested during 2014, 2015 and 2016 was $7,072,923, $6,467,294 and $8,233,220 respectively. As of December 31, 2015 and December 31, 2016, the total remaining unrecognized compensation cost, net of forfeitures, related to stock options granted was $8.6 million and $4.2 million respectively, each of which is expected to be recognized over a weighted average period of approximately 1.4 years. The intrinsic value of options exercised was $396,619 and $126,651 for the years ended December 31, 2015 and December 31, 2016, respectively. Restricted Stock Units In May 2011, the Company adopted and granted awards under a performance-based RSU program (the “2011 PRSU Program”) under the 2010 Plan. As of December 31, 2016, the performance deadline of May 26, 2016 had passed and all PRSU awards had expired. Each unit represented an amount equal to one share of the Company’s common stock. The RSUs are service-based awards that will vest and be paid in the form of one share of the Company’s common stock for each RSU, generally in three or four equal annual installments beginning on the first anniversary of the date of grant of the RSU. As of December 31, 2016, the Company had 394,132 RSU awards outstanding. As of December 31, 2015 and 2016, the total remaining unrecognized compensation cost, net of forfeitures, related to RSUs was $1.6 million and $1.1 million, respectively, which is expected to be recognized over a weighted average period of approximately 1.5 and 1.4 years, respectively. The following table sets forth the number of RSUs that were granted, vested and forfeited in the periods indicated: Weighted-Average Restricted Grant Date Stock Units Fair Value Outstanding at January 1, 2014 — $ — Granted during year Vested during year Forfeited during year Outstanding at December 31, 2014 $ Outstanding at January 1, 2015 Granted during year Vested during year Forfeited during year Outstanding at December 31, 2015 Outstanding at January 1, 2016 $ Granted during year Vested during year Forfeited during year Outstanding at December 31, 2016 $ Employee Stock Purchase Plan Effective January 1, 2014, the Company implemented the ESPP. At January 1, 2016, 911,725 common shares were available for issuance under the ESPP. Shares may be issued under the ESPP twice a year. In the year ended December 31, 2016, plan participants purchased 86,571 shares of common stock under the ESPP at an average purchase price of $2.68 per share. At December 31, 2016, 825,154 shares were available for issuance under the ESPP.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	11. Income Taxes A reconciliation of the expected income tax benefit (expense) computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2014, 2015, and 2016: December 31, 2014 2015 2016 Income tax computed at federal statutory tax rate % % % State taxes, net of federal benefit % % % State taxes rate change, net of federal benefit % — — International operations % % % Research and development credits % % % Orphan drug credits % % % Equity compensation % % % Other % — — Change in valuation allowance % % % Total — — — At December 31, 2016, the Company had net operating loss carryforwards totaling approximately $212,363,000 and $273,989,000 for federal and state income taxes, respectively, that may be used to offset future taxable income. If not used, the net operating loss carryforwards and research and development credits will begin expiring in the year 2021. The Company has determined that it experienced a change in ownership as defined under Section 382 of the U.S. Internal Revenue Code (the “Code”), as a result of the public offering in August 2011. As a result, the future use of its net operating losses, after giving effect to net unrealized built-in gains, will be limited to approximately $201,900,000 for 2016 and $16,800,000 for 2017. Any available but unused amounts will become available for use in all successive years, subject to certain limitations. Utilization of these net operating loss carryforwards would require the Company to generate future taxable income prior to their expiration. Furthermore, the utilization of the net operating loss carryforwards could be limited beyond the Company's generation of taxable income if a change in the underlying ownership of the Company's common stock has occurred, resulting in a limitation on the amounts that could be utilized in any given period under Section 382 of the Code. Net deferred tax assets and liabilities are comprised of the following: December 31, 2015 2016 Deferred tax assets Net operating loss carryforwards $ $ Research and development credit carryforwards Orphan drug credit Stock options Other Deferred tax assets Deferred tax liabilities Deferred revenue — Property and equipment Deferred tax liabilities $ $ Net deferred tax asset before valuation allowance $ $ Less valuation allowance Net deferred tax assets $ — $ — For the year ended December 31, 2016, net operating loss carryforwards in the table above have been reduced by $3.4 million of uncertain tax liabilities. A reconciliation of the beginning and ending amount of the unrecognized tax positions is as follows: Unrecognized Tax Positions Balance at January 1, 2016 $ — Additions based on tax positions related to the current year Additions for tax positions of prior years — Reductions for tax positions of prior years — Settlements — Balance at December 31, 2016 $ Balance at December 31, 2016 $ At December 31, 2016 there were no uncertain tax liabilities that if recognized would affect the annual effective tax rate. The Company does not recognize interest accrued related to unrecognized tax liabilities.

Collaborations

Collaborations	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Arrangement Disclosure [Text Block]	12. Collaborations In October 2007, the Company entered into an exclusive worldwide license with R&D Biopharmaceuticals to research, develop, and commercialize products containing conjugates of folate receptor targeting compounds and tubulysin compounds. In February 2011, this licensing agreement was assigned by R&D Biopharmaceuticals to Trientlgasse. The Company paid an upfront fee of $300,000 as research and development and pays $25,000 in annual maintenance fees unless a milestone is paid in a given year. In 2014, the Company paid $50,000 for the completion of toxicology studies in compliance with Good Laboratory Practice and $100,000 for dosing the first human patient with PSMA tubulysin. The Company could pay $5,900,000 in additional contingent payments upon the achievement of specific scientific, clinical, and regulatory milestones, in addition to royalties upon commercial sales. All payments have been expensed as research and development as incurred, as there is no alternate future use for this technology. In December 1995, as amended in October 1998, the Company entered into an exclusive license agreement with Purdue Research Foundation, which licenses the right under certain patents to the Company. The Company is obligated to pay an annual minimum royalty of $12,500 until commercial sales commence, following which time the payment of single digit royalty rates will commence. All payments have been expensed as incurred. The Company does not anticipate incurring any liabilities for vintafolide royalty payments based on the estimated timing of when commercial sales would commence, if development were to continue, and the expiration of the applicable patents. In December 2009, the Company entered into a financial term sheet to be incorporated into a written license agreement with Purdue Research Foundation for a patent related to prostate cancer. The agreement was signed and became effective on March 1, 2010. Pursuant to the exclusive license agreement, the Company is subject to minimum annual royalty payments of $15,000, payable until first commercial sale, following which time the minimum annual royalty payments increase to $100,000 and sales-based royalties are also payable at market rates when commercial sales commence. In addition, a milestone payment of $500,000 is payable upon approval of a new drug application in the U.S. In 2014, the Company paid a penalty as a milestone was not met. In 2015, the Company accrued a penalty which was paid in the first quarter of 2016 as an additional milestone was not met. In 2014, the Company entered into a Master License Agreement with Purdue Research Foundation. Under this license, the Company has the right to exclusively license patents and technology discovered under company funded research at Purdue University. If the Company decides to move forward with development of one or more of these technologies, the Company will be obligated to make an acceptance payment and the Company will also be obligated to make contingent payments upon the achievement of specific scientific, clinical and regulatory milestones. Certain scientific, clinical and regulatory milestones, in addition to internal resource targets must be met by the Company to avoid fees as consideration for waivers of potentially missed milestones. The Company is obligated to pay annual minimum payments until commercial sales commence, following which time the payments of royalties with market rates will commence, along with an annual royalty payment. Merck Collaboration Agreement In April 2012, the Company entered into a worldwide collaboration agreement with Merck Sharp & Dohme Research GmbH, a subsidiary of Merck & Co, Inc. (“Merck”), regarding the development and commercialization of vintafolide, which agreement was terminated by Merck effective September 15, 2014. As a result of the termination of the collaboration with Merck, the Company is no longer eligible for additional milestone payments from Merck. In addition, all obligations of the Company under the agreement have been fulfilled and the Company is not required to perform any additional services to Merck. Pursuant to the collaboration agreement, the Company received a $120.0 million non-refundable upfront payment and a $5.0 million milestone payment in 2012. Under the collaboration agreement, the Company was responsible for the majority of funding and completion of the Phase 3 PROCEED clinical trial of vintafolide for the treatment of patients with platinum-resistant ovarian cancer (“PROC”), which was terminated in May 2014. The Company was responsible for the execution of the Phase 2b TARGET trial of vintafolide for the treatment of second-line non-small cell lung cancer, which is now complete. Merck was responsible for the costs of the TARGET trial through September 15, 2014. For revenue recognition purposes, the Company viewed the collaboration with Merck as a multiple element arrangement. Multiple element arrangements are analyzed to determine whether the various performance obligations, or elements, can be separated or whether they must be accounted for as a single unit of accounting. The Company evaluated whether the delivered elements under the arrangement had value on a stand-alone basis and whether objective and reliable evidence of fair value of the undelivered element existed. Deliverables that did not meet these criteria were not evaluated separately for the purpose of revenue recognition. For a single unit of accounting, payments received were recognized in a manner consistent with the final deliverable. The Company determined that the deliverables related to the collaboration with Merck, including the licenses granted to Merck, as well as the Company performance obligations to provide various research and development services, would be accounted for as a single unit of account. This determination was made because the successful development of the therapeutic drug, vintafolide, is dependent on the companion diagnostic, etarfolatide, to select patients who are most likely to receive the most benefit from vintafolide. Given the nature of the combined benefit of the companion diagnostic and the therapeutic drug, the research and development services provided by the Company were essential to the overall arrangement as the Company had significant knowledge and technical know-how that was important to realizing the value of the licenses granted. Subsequent to the inception of the Merck arrangement, the Company evaluated the remaining deliverables for separation as items in the arrangement were delivered. The Company recognized the non-refundable $120.0 million upfront payment, the $5.0 million milestone payment and funding from the research and development services on a straight-line basis over the estimated performance period, which started at the date of execution of the agreement. Based on the termination of the PROCEED trial and receiving the notice of termination of the collaboration agreement in 2014, the Company concluded that all of its obligations under the agreement had been fulfilled and the Company was not required to perform any additional services to Merck, and as a result, the entire balance of deferred revenue related to the collaboration agreement was recognized in 2014. The Company recognized approximately $70.3 million of revenue related to the Merck collaboration during 2014. Though accounted for as a single unit of account for presentation purposes, the Company made an allocation of revenue recognized as collaboration revenue between the license and the services. This allocation was based upon the relative selling price of each deliverable. For the year ended December 31, 2014, license revenue was approximately $52.7 million, while research and development services revenue was approximately $17.6 million of the collaboration revenue. NMP License and Commercialization Agreement In August 2013, the Company entered into a license and commercialization agreement with Nihon Medi-Physic Co., LTD. (“NMP”) that grants NMP the right to develop and commercialize etarfolatide in Japan for use in connection with vintafolide in Japan. The Company received a $1.0 million non-refundable upfront payment, is eligible for up to $4.5 million based on the successful achievement of regulatory goals for etarfolatide in five different cancer indications and is eligible to receive double-digit percentage royalties on sales of etarfolatide in Japan. For revenue recognition purposes, the Company viewed the agreement with NMP as a multiple element arrangement. Multiple element arrangements are analyzed to determine whether the various performance obligations, or elements, can be separated or whether they must be accounted for as a single unit of accounting. The Company has identified the deliverables related to the collaboration with NMP, which include the license granted to NMP, as well as the obligation to provide pre-clinical and clinical supply of etarfolatide, to provide rights to NMP if a product is developed that replaces etarfolatide, the obligation for the Company to provide clinical data to NMP during the contract period and the coordination of development and commercialization efforts between the Company for vintafolide and NMP for etarfolatide in Japan. The Company’s deliverables will be accounted for as a single unit of account, therefore the non-refundable upfront payment is being recognized on a straight-line basis over the performance period. This determination was made because the successful development of etarfolatide in Japan requires the ongoing participation by the Company, including the development of the related therapeutic drug, vintafolide. The performance period over which the revenue will be recognized continues from the date of execution of the agreement through the end of 2033, the estimated termination date of the contract which is when the Company’s performance obligations will be completed. Any significant changes in the timing of the performance period could result in a change in the revenue recognition period. The Company had deferred revenue related to the agreement of approximately $0.8 million at December 31, 2016. Subsequent to the inception of the NMP arrangement, the Company evaluates the remaining deliverables for separation as items in the arrangement are delivered. The arrangement with NMP includes milestone payments of up to approximately $4.5 million and the milestones are based on the commencement of clinical trials in Japan for specific and non-specific indications and filing for approval in Japan for specific and non-specific indications. The Company evaluated each of these milestone payments and believes that all of the milestones are substantive as there is substantial performance risk that must occur in order for them to be met because the Company must complete additional clinical trials which show a positive outcome or receive approval from a regulatory authority and would be commensurate with the enhancement of value of the underlying intellectual property. To date, the products have not been approved in Japan and no revenue has been recognized related to the regulatory milestones or royalties as continued development of vintafolide is still an opportunity that the Company could pursue in the future. NMP has the right to terminate the collaboration agreement on 90 days notice prior to first commercial sale in Japan and six months notice after the first commercial sale in Japan. NMP also has the right to terminate the agreement on six months notice if the Company fails to launch vintafolide after receiving regulatory approval in Japan. NMP and the Company each have the right to terminate the agreement due to the material breach or insolvency of the other party. Upon termination of the agreement depending on the circumstances, the parties have varying rights and obligations with respect to licensing and related regulatory materials and data.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	13. Related-Party Transactions The Company funds research at Purdue University, the employer of one of its founders and current Chief Science Officer. Amounts included in research and development expenses were $1,000,000, $1,000,000 and $1,069,000 for the years ended December 31, 2014, 2015 and 2016, respectively. The Company leases a facility from Purdue Research Foundation, a nonprofit organization affiliated with Purdue University, the employer of the Company’s Chief Science Officer. The prior lease agreements have generally been renewed annually, and the current lease agreement expires December 31, 2017 with an option to extend the term. The amounts paid to Purdue Research Foundation related to the lease of this facility were $592,000, $588,000 and $597,000 for the years ended December 31, 2014, 2015 and 2016, respectively. At December 31, 2016, the Company had a balance of $182,000 in accounts payable and other liabilities due to Purdue University and Purdue Research Foundation related to the license agreements, the lease agreement and other operating expenses. In September 2011, the Company entered into exclusive worldwide licenses with On Target Laboratories, L.L.C. (“On Target”) to develop and commercialize products relating to the compound comprising the Company’s Folate and DUPA ligands and other certain Licensed Patents. On Target’s Chief Executive Officer is the brother of the Company’s Chief Science Officer. On Target is solely responsible for conducting research and development, seeking regulatory approval and commercialization of products. The Company received nonrefundable upfront license fees totaling $191,000 from On Target in December 2011. The Company has determined that the deliverables under this agreement do not meet the criteria required for separate accounting units for the purposes of revenue recognition, and as a result, the Company recognized revenue from non-refundable, upfront fees when the performance condition of delivering the licenses and certain consultation services had been achieved and there was reasonable assurance of collectability. If On Target fails to meet minimum spend requirements on research and development, the Company has the right to terminate the agreement. The Company will be entitled to receive minimum royalty payments annually based on net sales, but there is no guarantee that a commercial product will be developed and approved for commercial sales. The Company will also be entitled to reimbursement of expenses relating to patent expenses and payments to the inventors and Purdue University if certain milestones are met. During 2011, the Company received a $50,000 reimbursement from On Target for payments made to inventors for issued patents. The Company received $20,000 in annual maintenance license fees during each of 2014, 2015 and 2016, and received $50,614, $21,044 and $14,397 for reimbursable research and development expenses for 2014, 2015 and 2016, respectively.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Benefits Disclosure [Text Block]	14. Retirement Plans The Company maintains a 401(k) retirement savings plan to provide retirement benefits for substantially all of its employees. Participants in the plan may elect to contribute a portion of their annual compensation to the plan, limited to the maximum allowed by the Code. Prior to January 1, 2014 the Company did not match 401(k) contributions. Effective January 1, 2014, the Company implemented a matching contribution for the 401(k) contributions. For each of the years ended December 31, 2014, 2015 and 2016, the Company had approximately $0.3 million of expense related to the 401(k) employer match.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	15. Commitments and Contingencies On June 24, 2014, a complaint in a securities class action lawsuit was filed against the Company and one of its former officers and directors in the United States District Court for the Southern District of Indiana under the following caption: Tony Nguyen, on Behalf of Himself and All Others Similarly Situated v. Endocyte, Inc. and P. Ron Ellis (the “Nguyen Litigation”). On July 13, 2014, a nearly identical complaint in a securities class action lawsuit was filed against the Company and one of its former officers and directors in the United States District Court for the Southern District of Indiana under the following caption: Vivian Oh Revocable Trust, Individually and on Behalf of All Others Similarly Situated v. Endocyte, Inc. and P. Ron Ellis (the “Oh Litigation”). On September 22, 2014, the court named a lead plaintiff (“Lead Plaintiff”) and consolidated the Nguyen Litigation and the Oh Litigation under the following caption: Gopichand Vallabhaneni v. Endocyte, Inc. and P. Ron Ellis (the “Vallabhaneni Litigation”). On November 17, 2014, Lead Plaintiff filed a consolidated amended securities class action complaint (the “Amended Complaint”) against the Company, P. Ron Ellis, Beth Taylor, Michael A. Sherman, John C. Aplin, Philip S. Low, Keith E. Brauer, Ann F. Hanham, Marc Kozin, Peter D. Meldrum, Fred A. Middleton, Lesley Russell (the “Individual Defendants” and collectively with the Company, the “Endocyte Defendants”), and Credit Suisse Securities (USA) LLC and Citigroup Global Markets Inc. (the “Underwriter Defendants”). The court dismissed the lawsuit without prejudice on January 4, 2016, but granted Lead Plaintiff until February 1, 2016 to demonstrate sufficient facts to justify an amended pleading. Lead Plaintiff did not respond, and on February 2, 2016, the court amended the dismissal to be with prejudice and a final order was so entered. Lead Plaintiff appealed the final judgment on March 1, 2016. On March 31, 2016, the appeal was voluntarily dismissed, with prejudice. On September 23, 2014, a complaint in a shareholder derivative lawsuit was filed against all but one of the Company’s current directors and one of its former directors in the United States District Court for the Southern District of Indiana under the following caption: William Moore, Derivatively on Behalf of Nominal Defendant Endocyte, Inc. v. John C. Aplin, et al. (the “Moore Litigation”). The Company was named as a nominal defendant in the case. On October 31, 2014, a complaint in a shareholder derivative lawsuit nearly identical to the Moore Litigation was filed against all but one of the Company’s current directors and one of its former directors in the United States District Court for the Southern District of Indiana under the following caption: Victor Veloso, Derivatively on Behalf of Endocyte, Inc. v. John C. Aplin, et al. (the “Veloso Litigation”). The Company was named as a nominal defendant in the case. On December 31, 2014, the court appointed co-lead counsel and consolidated the Moore Litigation with the Veloso Litigation under the following caption: In re Endocyte, Inc. Derivative Litigation (the “Endocyte Derivative Litigation”). The lawsuit was voluntarily dismissed without prejudice on April 19, 2016. On November 6, 2014, a complaint was filed against the Company, one of its current executive officers, one of its former executive officers, Merck and one of Merck’s officers in the Superior Court of Tippecanoe County, Indiana under the following caption: Mohamad Hage and Jamele Hage v. Endocyte, Inc., P. Ron Ellis, Mike A. Sherman, Eric Rubin and Merck & Co., Inc. (the “Hage Litigation”). On July 21, 2016, the lawsuit was voluntarily dismissed, with prejudice.

Restructuring Costs

Restructuring Costs	12 Months Ended
	Dec. 31, 2016
Restructuring Costs [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	16. Restructuring Costs The Company terminated the PROCEED trial in May 2014 after the interim futility analysis indicated that vintafolide did not demonstrate efficacy on the pre-specified outcome of progression-free survival for the treatment of PROC. As a result, the Company ceased its pre-launch commercial activities in Europe and implemented staff reductions in Europe and in the U.S. All employee and contract termination expenses were recorded and paid in the year ended December 31, 2014. The PROCEED trial termination expenses were paid over the years ended December 31, 2014, 2015 and 2016. At December 31, 2016, the Company had no remaining accrual balance related to the PROCEED trial termination. The following table summarizes the restructuring accruals for the years ended December 31, 2014, 2015 and 2016: Employee and PROCEED Contract Trial Termination Termination Accrual Accrual Total Balance, January 1, 2014 $ — $ — $ — Charges for the year ended December 31, 2014 Amounts paid in the year ended December 31, 2014 Balance, December 31, 2014 $ — $ $ Balance, January 1, 2015 — Revised estimates in the year ended December 31, 2015 — Amounts paid in the year ended December 31, 2015 — Balance, December 31, 2015 $ — $ $ Balance, January 1, 2016 $ — $ $ Revised estimates in the year ended December 31, 2016 — Amounts paid in the year ended December 31, 2016 — Balance, December 31, 2016 $ — $ — $ —

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	17. Selected Quarterly Financial Data (unaudited) The following tables summarize the unaudited statements of operations for each quarter of 2016 and 2015 (in thousands except share and per share amounts): Quarters Ended March 31, June 30, September 30, December 31, 2016 Revenue $ $ $ $ Operating expenses: Research and development General and administrative Loss from operations Interest income, net Other expense, net — Net loss $ $ $ $ Net loss per share-basic and diluted (1) (2) $ $ $ $ Weighted average common shares outstanding – basic and diluted (2) Quarters Ended March 31, June 30, September 30, December 31, 2015 Revenue $ $ $ $ Operating expenses: Research and development General and administrative Loss from operations Interest income, net Other income (expense), net Net loss $ $ $ $ Net loss per share-basic and diluted (1) (2) $ $ $ $ Weighted average common shares outstanding – basic and diluted (2) $ $ $ $ (1) Per common share amounts for the quarters and full years have been calculated separately. Accordingly, the sum of quarterly amounts may not equal the annual amount due to differences in the weighted average common shares outstanding during each period, principally due to the effect of share issuances by the Company during the year. (2) Diluted weighted average common shares outstanding are identical to basic weighted average common shares outstanding and diluted net loss per share is identical to basic net loss per share for all quarters of 2015 and 2016 because common share equivalents are excluded from the calculations of diluted weighted average common shares outstanding for those quarters, as their effect is anti-dilutive.

Significant Accounting Polici24

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Endocyte, Inc. and its subsidiaries and all intercompany amounts have been eliminated as of December 31, 2014 and 2015. The accompanying financial statements for the year ended December 31, 2016 include only the accounts of Endocyte, Inc. as the Company dissolved Endocyte Europe GmbH and Endocyte Europe B.V. in the fourth quarter of 2015 and the first quarter of 2016, respectively. There were no intercompany transactions in the year ended December 31, 2016 and no intercompany balances as of December 31, 2016. The consolidated financial statements are prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). Subsequent events have been evaluated through the date of issuance, which is the same as the date this Form 10-K is filed with the Securities and Exchange Commission.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual amounts may differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers cash and all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents consist primarily of FDIC insured deposits with multiple banks and money market instruments that are maintained by an investment manager.
Investments	Investments Investments consist primarily of investments in U.S. Treasuries, U.S. Government agency obligations and corporate debt securities, which could also include commercial paper, that are maintained by an investment manager. U.S. government agency investments relate to investments in Fannie Mae, Freddie Mac and Federal Home Loan Bank. Management determines the appropriate classification of marketable securities at the time of purchase and reevaluates such classification as of each balance sheet date. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities are included in other income. The Company considers and accounts for other-than-temporary impairments according to the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 320, Investments — Debt and Equity Securities (“ASC 320”). The cost of securities sold is based on the specific-identification method. Discounts and premiums on debt securities are amortized to interest income and expense over the term of the security.
Property and Equipment	Property and Equipment Property and equipment are stated at cost and are being depreciated using the straight-line method over estimated useful lives, which range from three to seven years.
Licenses and Patents	Licenses and Patents Licenses and patent costs are expensed as incurred as the Company does not believe there is an alternate future use for the costs. Licenses are classified as research and development expenses and patents are classified as general and administrative expenses in the consolidated statements of operations.
Long-Lived Assets	Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment when events or changes in business conditions indicate that their full carrying value may not be fully recoverable.
Leases	Leases The Company evaluates all leases to determine whether they should be accounted for as operating or capital leases.
Revenue Recognition	Revenue Recognition The Company recognizes revenues from license and collaboration agreements when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the fee is fixed or determinable, and there is reasonable assurance that the related amounts are collectible in accordance with ASC Topic 605, Revenue Recognition (“ASC 605”). The Company’s license and collaboration agreements may contain multiple elements, including grants of licenses to intellectual property rights, agreement to provide research and development services and other deliverables. The deliverables under such arrangements are evaluated under ASC Subtopic 605-25, Multiple-Element Arrangements (“ASC 605-25”). Under ASC 605-25, each required deliverable is evaluated to determine whether it qualifies as a separate unit of accounting based on whether the deliverable has “stand-alone value” to the customer. The arrangement’s consideration that is fixed or determinable, excluding contingent milestone payments, is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. In general, the consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. Upfront payments for licensing the Company’s intellectual property are evaluated to determine if the licensee can obtain stand-alone value from the license separate from the value of the research and development services and other deliverables in the arrangement to be provided by the Company. If at the inception of an arrangement the Company determines that the license does not have stand-alone value separate from the research and development services or other deliverables, the license, services and other deliverables are combined as one unit of account and upfront payments are recorded as deferred revenue on the balance sheet and are recognized in a manner consistent with the final deliverable. Subsequent to the inception of an arrangement, the Company evaluates the remaining deliverables for separation as items in the arrangement are delivered. When stand-alone value is identified, the related consideration is recorded as revenue in the period in which the license or other intellectual property rights are delivered. In those circumstances where research and development services or other deliverables are combined with the license, and multiple services are being performed such that a common output measure to determine a pattern of performance cannot be discerned, the Company recognizes amounts received on a straight line basis over the performance period. Such amounts are recorded as collaboration revenue. Any subsequent reimbursement payments, which are contingent upon the Company’s future research and development expenditures, will be recorded as collaboration revenue and will be recognized on a straight-line basis over the performance period using the cumulative catch up method. The costs associated with these activities are reflected as a component of research and development expense in the statements of operations in the period incurred. In the event of an early termination of a collaboration agreement, any deferred revenue is recognized in the period in which all obligations of the Company under the agreement have been fulfilled. Milestone payments under collaborative arrangements are triggered either by the results of the Company’s research and development efforts, achievement of regulatory goals or by specified sales results by a third-party collaborator. Milestones related to the Company’s development-based activities may include initiation of various phases of clinical trials and applications and acceptance for product approvals by regulatory agencies. Due to the uncertainty involved in meeting these development-based milestones, the determination is made at the inception of the collaboration agreement whether the development-based milestones are considered to be substantive (i.e. not just achieved through passage of time). In addition, the amounts of the payments assigned thereto are considered to be commensurate with the enhancement of the value of the delivered intellectual property as a result of the Company’s performance. Because the Company’s involvement is necessary to the achievement of development-based milestones, the Company would account for development-based milestones as revenue upon achievement of the substantive milestone events. Milestones related to sales-based activities may be triggered upon events such as first commercial sale of a product or when sales first achieve a defined level. Since these sales-based milestones would be achieved after the completion of the Company’s development activities, the Company would account for the sales-based milestones in the same manner as royalties, with revenue recognized upon achievement of the milestone. Royalties based on reported sales of licensed products will be recognized based on contract terms when reported sales are reliably measurable and collectability is reasonably assured. To date, none of the Company’s products have been approved and therefore the Company has not earned any royalty revenue from product sales. In territories where the Company and a collaborator may share profit, the revenue would be recorded in the period earned. The Company often is required to make estimates regarding drug development and commercialization timelines for compounds being developed pursuant to a collaboration agreement. Because the drug development process is lengthy and the Company’s collaboration agreements typically cover activities over several years, this approach often results in the deferral of significant amounts of revenue into future periods. In addition, because of the many risks and uncertainties associated with the development of drug candidates, the Company’s estimates regarding the period of performance may change in the future. Any change in the Company’s estimates or a termination of the arrangement could result in substantial changes to the period over which the revenues are recognized.
Research and Development Expense	Research and Development Expenses Research and development expenses represent costs associated with the ongoing development of SMDCs and companion imaging agents and include salaries and employee benefits, supplies, facility costs related to research activities, and expenses for clinical trials. The Company records accruals for clinical trial expenses based on the estimated amount of work completed. The Company monitors patient enrollment levels and related activities to the extent possible through internal reviews, correspondence, and discussions with research organizations. In the event that a clinical trial is terminated early, the Company records, in the period of termination, an accrual for the estimated remaining costs to complete the trial. Upfront payments made in connection with business collaborations and research and development arrangements are evaluated under ASC Subtopic 730-20, Research and Development Arrangements . Upfront payments made in connection with business development collaborations are expensed as research and development costs, as the assets acquired do not have alternative future use. Amounts related to future research and development are capitalized as prepaid research and development and are expensed over the service period based upon the level of services provided. As of December 31, 2016, the Company had approximately $1.0 million of capitalized research and development costs included in prepaid expenses.
Shock-Based Compensation	Stock-Based Compensation The Company accounts for its stock-based compensation pursuant to ASC Topic 718, Compensation — Stock Compensation (“ASC 718”), which requires the recognition of the fair value, or calculated value for nonpublic entities, of stock-based compensation in net income. Stock-based compensation consists of stock options, which are granted at exercise prices at or above the fair market value of the Company’s common stock on the dates of grant, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), and shares available for purchase under the Company’s 2010 Employee Stock Purchase Plan (“ESPP”). For PRSUs issued by the Company, stock-based compensation expense would be recognized if and when the Company determines that it is probable that the performance conditions will be achieved. For RSUs issued by the Company, stock-based compensation expense is recognized ratably over the service period. The Company recognizes compensation cost based on the grant-date fair value estimated in accordance with the provisions of ASC 718.
Net Income (Loss) Per Share	Net Income (Loss) Per Share The Company calculates basic net income (loss) per share based on the weighted-average number of outstanding common shares. The Company calculates diluted net income (loss) per share based on the weighted-average number of outstanding common shares plus the effect of dilutive securities.
Income Taxes	Income Taxes The Company accounts for income taxes under the liability method in accordance with the provision of ASC Topic 740, Income Taxes (“ASC 740”). ASC 740 requires recognition of deferred taxes to provide for temporary differences between financial reporting and tax basis of assets and liabilities. Deferred taxes are measured using enacted tax rates expected to be in effect in a year in which the basis difference is expected to reverse. The Company continues to record a valuation allowance for the full amount of deferred tax assets, which would otherwise be recorded for tax benefits relating to operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not. The Company accounts for uncertain income tax positions recognized in the financial statements in accordance with Accounting Standards Update (“ASU”) No. 2009-06. This guidance prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return and provides guidance on derecognition of tax benefits, classification on the balance sheet, interest and penalties, accounting in interim periods, disclosure, and transition.
Segment Information	Segment Information Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company had performed clinical trials globally and established a subsidiary in The Netherlands to assist in the administration of filing applications in Europe and a subsidiary in Switzerland for commercial pre-launch activities in Europe. The applications filed in Europe were withdrawn in May 2014 and the pre-launch activities in Europe ceased. The Company dissolved Endocyte Europe GmbH in the fourth quarter of 2015 and dissolved Endocyte Europe B.V. in the first quarter of 2016. All long-lived assets are held in the U.S. The Company views its operations and manages its business in one operating segment.

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Schedule of common stock equivalents excluded due to anti-dilutive effect	Year Ended December 31, 2014 2015 2016 Outstanding common stock options Outstanding warrants Outstanding PRSUs — Outstanding RSUs Shares to be purchased under the ESPP Total
Schedule of dilutive shares included in determination of weighted average shares outstanding	Year Ended December 31, 2014 Outstanding common stock options Outstanding warrants Outstanding RSUs Shares to be purchased under the ESPP Total

Other Comprehensive Income (L26

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2016
Other Comprehensive Income (Loss), Tax [Abstract]
Schedule of components of other comprehensive income	Foreign Accumulated Currency Unrealized Net Other Translation Gains (Losses) Comprehensive Gains (Losses) on Securities Gains (Losses) Balance at December 31, 2013 $ $ $ Unrealized loss Net amount reclassified to net income — Other comprehensive loss Balance at December 31, 2014 $ $ $ Unrealized gain (loss) Net amount reclassified to net loss Other comprehensive income Balance at December 31, 2015 $ — $ $ Unrealized gain — Net amount reclassified to net loss — Other comprehensive income — Balance at December 31, 2016 $ — $ $
Schedule of reclassifications out of AOCI	Reclassifications Out of Accumulated Other Comprehensive Income (Loss) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Year Ended Year Ended Year Ended Consolidated Details about Accumulated Other December 31, December 31, December 31, Statements of Operations and Comprehensive Income (Loss) Components 2014 2015 2016 Comprehensive Income (Loss) Unrealized Net Gains (Losses) on Securities $ $ $ Other income (expense) Foreign Currency Translation Losses — — Other income (expense) Total Reclassifications for the Period $ $ $

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Schedule of cash and cash equivalents and investments	The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2015: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ $ $ — $ Cash equivalents FDIC insured deposits and money market funds — Cash and cash equivalents $ $ $ — $ Short-term investments (due within 1 year) U.S. government treasury obligations $ $ $ — $ U.S. government agency obligations — Corporate obligations — Total short-term investments $ $ $ $ The following table summarizes the fair value of cash and cash equivalents and investments as of December: 31, 2016: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ $ $ — $ Cash equivalents FDIC insured deposits and money market funds — Cash and cash equivalents $ $ $ — $ Short-term investments (due within 1 year) U.S. government treasury obligations $ $ $ — $ Corporate obligations — Total short-term investments $ $ $ $

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property and equipment	Estimated December 31, Useful Lives 2015 2016 Laboratory equipment 7 $ $ Office equipment and software 3 – 7 Leasehold improvements 7 Assets not in service Less accumulated depreciation $ $

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2016
Leases [Abstract]
Schedule of future minimum lease payment for noncancellable operating leases	Future minimum lease payments for noncancellable operating leases as of December 31, 2016, are as follows: 2017 $ 2018 2019 — 2020 — 2021 — Thereafter — Total minimum lease payments $

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Schedule of weighted-average valuation assumptions	Year Ended December 31, 2014 2015 2016 Expected volatility % % % Risk-free interest rate % % % Weighted-average expected life (in years) Dividend yield % % %
Schedule of stock option activity	The Company’s stock option activity and related information are summarized as follows: Weighted-Average Remaining Weighted-Average Contractual Term Aggregate Options Exercise Price (In Years) Intrinsic Value Outstanding at January 1, 2014 $ Granted during year Exercised during year Expired during year Forfeited during year Outstanding at December 31, 2014 $ $ Exercisable at December 31, 2014 Outstanding at January 1, 2015 Granted during year Exercised during year Expired during year Forfeited during year Outstanding at December 31, 2015 $ $ Exercisable at December 31, 2015 Outstanding at January 1, 2016 Granted during year Exercised during year Expired during year Forfeited during year Outstanding at December 31, 2016 $ $ Exercisable at December 31, 2016
Schedule of nonvested stock option activity	Weighted-Average Options Grant Date Value Nonvested stock options at January 1, 2014 $ Granted during year Vested during year Forfeited during year Nonvested at December 31, 2014 $ Nonvested stock options at January 1, 2015 $ Granted during year Vested during year Forfeited during year Nonvested at December 31, 2015 $ Nonvested stock options at January 1, 2016 $ Granted during year Vested during year Forfeited during year Nonvested at December 31, 2016 $
Schedule of restricted stock unit activity	Weighted-Average Restricted Grant Date Stock Units Fair Value Outstanding at January 1, 2014 — $ — Granted during year Vested during year Forfeited during year Outstanding at December 31, 2014 $ Outstanding at January 1, 2015 Granted during year Vested during year Forfeited during year Outstanding at December 31, 2015 Outstanding at January 1, 2016 $ Granted during year Vested during year Forfeited during year Outstanding at December 31, 2016 $

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of effective income tax rate reconciliation	December 31, 2014 2015 2016 Income tax computed at federal statutory tax rate % % % State taxes, net of federal benefit % % % State taxes rate change, net of federal benefit % — — International operations % % % Research and development credits % % % Orphan drug credits % % % Equity compensation % % % Other % — — Change in valuation allowance % % % Total — — —
Schedule of deferred tax assets and liabilities	December 31, 2015 2016 Deferred tax assets Net operating loss carryforwards $ $ Research and development credit carryforwards Orphan drug credit Stock options Other Deferred tax assets Deferred tax liabilities Deferred revenue — Property and equipment Deferred tax liabilities $ $ Net deferred tax asset before valuation allowance $ $ Less valuation allowance Net deferred tax assets $ — $ —
Schedule of unrecognized tax benefits	Unrecognized Tax Positions Balance at January 1, 2016 $ — Additions based on tax positions related to the current year Additions for tax positions of prior years — Reductions for tax positions of prior years — Settlements — Balance at December 31, 2016 $ Balance at December 31, 2016 $

Restructuring Costs (Tables)

Restructuring Costs (Tables)	12 Months Ended
	Dec. 31, 2016
Restructuring Costs [Abstract]
Schedule of restructuring and related costs	The following table summarizes the restructuring accruals for the years ended December 31, 2014, 2015 and 2016: Employee and PROCEED Contract Trial Termination Termination Accrual Accrual Total Balance, January 1, 2014 $ — $ — $ — Charges for the year ended December 31, 2014 Amounts paid in the year ended December 31, 2014 Balance, December 31, 2014 $ — $ $ Balance, January 1, 2015 — Revised estimates in the year ended December 31, 2015 — Amounts paid in the year ended December 31, 2015 — Balance, December 31, 2015 $ — $ $ Balance, January 1, 2016 $ — $ $ Revised estimates in the year ended December 31, 2016 — Amounts paid in the year ended December 31, 2016 — Balance, December 31, 2016 $ — $ — $ —

Selected Quarterly Financial 33

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	The following tables summarize the unaudited statements of operations for each quarter of 2016 and 2015 (in thousands except share and per share amounts): Quarters Ended March 31, June 30, September 30, December 31, 2016 Revenue $ $ $ $ Operating expenses: Research and development General and administrative Loss from operations Interest income, net Other expense, net — Net loss $ $ $ $ Net loss per share-basic and diluted (1) (2) $ $ $ $ Weighted average common shares outstanding – basic and diluted (2) Quarters Ended March 31, June 30, September 30, December 31, 2015 Revenue $ $ $ $ Operating expenses: Research and development General and administrative Loss from operations Interest income, net Other income (expense), net Net loss $ $ $ $ Net loss per share-basic and diluted (1) (2) $ $ $ $ Weighted average common shares outstanding – basic and diluted (2) $ $ $ $ (1) Per common share amounts for the quarters and full years have been calculated separately. Accordingly, the sum of quarterly amounts may not equal the annual amount due to differences in the weighted average common shares outstanding during each period, principally due to the effect of share issuances by the Company during the year. Diluted weighted average common shares outstanding are identical to basic weighted average common shares outstanding and diluted net loss per share is identical to basic net loss per share for all quarters of 2015 and 2016 because common share equivalents are excluded from the calculations of diluted weighted average common shares outstanding for those quarters, as their effect is anti-dilutive.

Nature of Business and Organi34

Nature of Business and Organization (Details)	Apr. 02, 2014shares	Dec. 31, 2016USD ($)subsidiary	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of wholly-owned subsidiaries now dissolved | subsidiary		2
Stock Issued During Period, Shares, New Issues | shares	5,175,000
Proceeds from Issuance of Common Stock | $		$ 0	$ 0	$ 101,904,977

Significant Accounting Polici35

Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2016USD ($)segmentproductTransaction
Basis of Presentation
Number of intercompany transactions | Transaction	0
Intercompany balances at period end	$ 0
Revenue Recognition [Abstract]
Number of products approved for sale | product	0
Segment Information
Number of Operating Segments | segment	1
Minimum
Property and equipment useful lives
Property, Plant and Equipment, Useful Life	3 years
Maximum
Property and equipment useful lives
Property, Plant and Equipment, Useful Life	7 years
Prepaid Expenses
Revenue Recognition [Abstract]
Capitalized research and development costs	$ 1,000,000

Net Income (Loss) per Share - a

Net Income (Loss) per Share - antidilutive (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	6,880,767	6,290,870	5,541,050
Outstanding common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	6,447,594	5,686,815	5,096,674
Outstanding warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	34,647	34,647	34,647
PRSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	0	213,758	245,396
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	394,132	351,414	161,439
Employee Stock Purchase Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	4,394	4,236	2,894

Net Income (Loss) per Share - d

Net Income (Loss) per Share - dilutive (Details)	12 Months Ended
	Dec. 31, 2014shares
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	1,515,749
Outstanding common stock options
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	1,494,796
Outstanding warrants
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	5,433
RSUs
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	14,128
Employee Stock Purchase Plan
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	1,392

Other Comprehensive Income (L38

Other Comprehensive Income (Loss) - components (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 171,346,137	$ 205,004,118	$ 88,228,721
Net amount reclassified to net income (loss)	1,295	47,040	3,442
Balance at end of period	137,147,363	171,346,137	205,004,118
Foreign Currency Translation Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	0	(50,592)	(11,816)
Unrealized gain (loss)	0	(1,352)	(38,776)
Net amount reclassified to net income (loss)	0	51,944	0
Other comprehensive income (loss)	0	50,592	(38,776)
Balance at end of period	0	0	(50,592)
Unrealized Net Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(79,399)	(93,336)	68,507
Unrealized gain (loss)	36,908	18,841	(165,285)
Net amount reclassified to net income (loss)	1,295	(4,904)	3,442
Other comprehensive income (loss)	38,203	13,937	(161,843)
Balance at end of period	(41,196)	(79,399)	(93,336)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(79,399)	(143,928)	56,691
Unrealized gain (loss)	36,908	17,489	(204,061)
Net amount reclassified to net income (loss)	1,295	47,040	3,442
Other comprehensive income (loss)	38,203	64,529	(200,619)
Balance at end of period	$ (41,196)	$ (79,399)	$ (143,928)

Other Comprehensive Income (L39

Other Comprehensive Income (Loss) - Reclassifications (Details) - USD ($)	3 Months Ended							12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Nonoperating Income (Expense), Total	$ (25)	$ (1)	$ (3)	$ (55)	$ 170	$ (7)	$ (57)	$ (28,461)	$ 51,645	$ (144,698)
Total reclassifications for the Period								1,295	47,040	3,442
Unrealized Net Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassifications for the Period								1,295	(4,904)	3,442
Unrealized Net Gains (Losses) on Securities | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Nonoperating Income (Expense), Total								1,295	(4,904)	3,442
Foreign Currency Translation Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassifications for the Period								$ 0	51,944	$ 0
Foreign Currency Translation Gains (Losses) | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Nonoperating Income (Expense), Total									$ 51,944

Investments (Details)

Investments (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash
Cash	$ 6,249,703	$ 5,154,191
Cash equivalents
FDIC insured deposits and money market funds	24,978,489	10,277,431
Cash and cash equivalents	31,228,192	15,431,622	$ 45,533,443	$ 52,846,940
Short-term Investments
Short-term investments (due within 1 year)
Available-for-sale Securities	106,979,224	158,168,832
Available-for-sale Securities, Amortized Cost Basis	107,020,420	158,248,231
Short-term Investments | U.S. government treasury obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	86,053,755	73,560,085
Available-for-sale Securities, Amortized Cost Basis	86,078,622	73,593,081
Short-term Investments | U.S. government agency obligations
Short-term investments (due within 1 year)
Available-for-sale Securities		55,670,043
Available-for-sale Securities, Amortized Cost Basis		55,702,099
Short-term Investments | Corporate obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	20,925,469	28,938,704
Available-for-sale Securities, Amortized Cost Basis	20,941,799	28,953,051
Level 1
Cash
Cash	6,249,703	5,154,191
Cash equivalents
FDIC insured deposits and money market funds	24,978,489	10,277,431
Cash and cash equivalents	31,228,192	15,431,622
Level 1 | Short-term Investments
Short-term investments (due within 1 year)
Available-for-sale Securities	86,053,755	129,230,128
Level 1 | Short-term Investments | U.S. government treasury obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	86,053,755	73,560,085
Level 1 | Short-term Investments | U.S. government agency obligations
Short-term investments (due within 1 year)
Available-for-sale Securities		55,670,043
Level 1 | Short-term Investments | Corporate obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	0
Level 2
Cash
Cash	0
Cash equivalents
FDIC insured deposits and money market funds	0
Cash and cash equivalents	0
Level 2 | Short-term Investments
Short-term investments (due within 1 year)
Available-for-sale Securities	20,925,469	28,938,704
Level 2 | Short-term Investments | U.S. government treasury obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	0
Level 2 | Short-term Investments | Corporate obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	$ 20,925,469	$ 28,938,704

Investments unrealized gains (D

Investments unrealized gains (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Unrealized Gain on Securities	$ 8,257	$ 5,690
Unrealized Loss on Securities	49,453	85,089
Realized Gain on Securities	0	1,667
Realized Loss on Securities	$ 53	$ 0

Property and Equipment (Details

Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 8,457,450	$ 7,755,963
Less accumulated depreciation	(5,252,373)	(4,357,565)
Property, Plant and Equipment, Net	3,205,077	3,398,398
Depreciation, Depletion and Amortization [Abstract]
Depreciation	$ 919,809	886,710	$ 857,055
Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Useful Life	7 years
Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Useful Life	3 years
Laboratory Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 6,666,506	6,022,585
Property, Plant and Equipment, Useful Life	7 years
Office Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 1,347,768	1,271,847
Office Equipment [Member] | Maximum
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Useful Life	7 years
Office Equipment [Member] | Minimum
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Useful Life	3 years
Leasehold Improvements [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 424,176	408,153
Property, Plant and Equipment, Useful Life	7 years
Assets not in service
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 19,000	$ 53,378

Warrant (Details)

Warrant (Details)	Dec. 31, 2016$ / sharesshares
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares	34,647
Common Stock [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares	$ 8.12

Leases (Details)

Leases (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Leases [Abstract]
Rent expense for operating leases	$ 743,323	$ 736,249	$ 866,768
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,017	767,450
2,018	26,677
Total minimum lease payments	$ 794,127

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Options assumptions (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Assumptions
Expected volatility		98.83%	106.38%	102.86%
Risk-free interest rate		1.47%	1.55%	1.98%
Weighted-average expected life (in years)		6 years 7 months 6 days	6 years 4 months 24 days	6 years 7 months 6 days
Dividend yield		0.00%	0.00%	0.00%
Value of options granted during period		$ 2,838,053	$ 4,884,534
P. Ron Ellis
Fair Value Assumptions
Additional compensation cost due to modification	$ 2,800,000
1997 And 2007 Plans | Service based vesting
Additional disclosures
Vesting period		4 years
1997 And 2007 Plans | Service based vesting, first period
Additional disclosures
Vesting period		2 years
Shares that will vest (as a percentage)		50.00%
1997 And 2007 Plans | Performance based vesting
Additional disclosures
Vesting period		4 years
2010 Equity Incentive Plan
Stock-Based Compensation Plans
Shares authorized and reserved		11,003,563	9,742,563
2010 Equity Incentive Plan | Minimum
Additional disclosures
Vesting period		3 years
2010 Equity Incentive Plan | Maximum
Additional disclosures
Vesting period		4 years

Stockholders' Equity - Stock 46

Stockholders' Equity - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 8,233,220	$ 6,467,294	$ 7,072,923
Unrecognized compensation cost, net of forfeitures	$ 4,200,000	$ 8,600,000
Weighted average period to recognize stock compensation expense		1 year 4 months 24 days
Options
Outstanding, Beginning Balance	5,686,815	5,096,674	5,246,465
Granted during period	1,100,997	1,126,672	1,065,386
Exercised during period	(129,638)	(146,046)	(399,654)
Expired during period	(28,369)	(156,160)	(244,121)
Forfeited during period	(182,211)	(234,325)	(571,402)
Outstanding, Ending Balance	6,447,594	5,686,815	5,096,674
Weighted-Average Exercise Price
Outstanding, Beginning Balance	$ 6.87	$ 7.29	$ 6.76
Granted during period	3.21	5.23	10.54
Exercised during period	2.01	2.60	3.23
Expired during period	7.65	11.03	9.17
Forfeited during period	4.45	8.05	10.49
Outstanding, Ending Balance	$ 6.41	$ 6.87	$ 7.29
Additional disclosures
Options, Exercisable	4,666,628	3,391,069	2,695,278
Weighted Average Exercise Price, Exercisable	$ 6.76	$ 6.46	$ 5.89
Weighted Average Remaining Contractual Term	6 years 2 months 1 day	6 years 6 months 7 days	6 years 10 months 13 days
Weighted Average Remaining Contractual Term exercisable at end of period	5 years 4 months 2 days	5 years 4 months 13 days	5 years 8 months 5 days
Aggregate Intrinsic Value	$ 33,283	$ 1,432,306	$ 6,329,518
Aggregate Intrinsic Value, exercisable at end of period	$ 33,283	$ 1,333,875	$ 4,986,059

Stockholders' Equity - nonveste

Stockholders' Equity - nonvested stock options (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Options, Nonvested stock options, Beginning Balance	2,295,746	2,401,396	2,977,027
Options, Granted during year	1,100,997	1,126,672	1,065,386
Options, Vested during year	(1,433,566)	(997,997)	(1,069,615)
Options, Forfeited during year	(182,211)	(234,325)	(571,402)
Options, Nonvested stock options, Ending Balance	1,780,966	2,295,746	2,401,396
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-Average Grant Date Value, Nonvested stock options, Beginning Balance	$ 6.05	$ 7.07	$ 6.62
Weighted-Average Grant Date Value, Granted during year	2.58	4.34	8.62
Weighted-Average Grant Date Value, Vested during year	5.74	6.48	6.61
Weighted-Average Grant Date Value, Forfeited during year	3.57	6.37	8.36
Weighted-Average Grant Date Value, Nonvested stock options, Ending Balance	$ 4.41	$ 6.05	$ 7.07
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 126,651	$ 396,619

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock Units
Unrecognized compensation cost			$ 1.6
Weighted average period to recognize stock compensation expense			1 year 4 months 24 days
RSUs
Restricted Stock Units
Unrecognized compensation cost		$ 1.1
Weighted average period to recognize stock compensation expense		1 year 4 months 24 days	1 year 6 months
Restricted Stock Units
Outstanding at beginning of period		351,414	161,439
Granted during period		254,538	260,976	196,710
Vested during period		(177,078)	(40,333)	(1,875)
Forfeited during period		(34,742)	(30,668)	(33,396)
Outstanding at the end of the period		394,132	351,414	161,439
Weighted-Average Grant Date Fair Value
Outstanding beginning of period		$ 7.03	$ 11.11
Granted during period		3.21	5.17	$ 11.11
Vested during period		6.71	11.11	11.11
Forfeited during period		4.13	8.07	11.11
Outstanding end of period		$ 4.96	$ 7.03	$ 11.11
RSUs | 2010 Equity Incentive Plan
Restricted Stock Units
Number of shares of common stock to be paid upon vesting of RSU		1
PRSUs | 2011 PRSU Program
Restricted Stock Units
Number of shares of common stock to be paid upon vesting of RSU	1
Minimum | 2010 Equity Incentive Plan
Restricted Stock Units
Vesting period		3 years
Maximum | 2010 Equity Incentive Plan
Restricted Stock Units
Vesting period		4 years
Service based vesting | Minimum | RSUs
Restricted Stock Units
Vesting period		3 years
Service based vesting | Maximum | RSUs
Restricted Stock Units
Vesting period		4 years

Stockholders' Equity - ESPP (De

Stockholders' Equity - ESPP (Details) - Employee Stock Purchase Plan - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Employee Stock Purchase Plan (Abstract)
Shares available for issuance under ESPP	825,154	911,725
Number of shares purchased under ESPP	86,571
Average purchase price of shares under ESPP	$ 2.68

Income Taxes - Effective rate r

Income Taxes - Effective rate reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax computed at federal statutory tax rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	3.30%	3.20%	6.30%
State taxes rate change, net of federal benefit	0.00%	0.00%	30.40%
International operations	(0.70%)	(4.80%)	6.60%
Research and development credits	4.00%	3.80%	(22.60%)
Orphan drug credits	0.60%	0.90%	(57.40%)
Equity compensation	(3.70%)	(2.00%)	16.60%
Other	0.00%	0.00%	(2.10%)
Change in valuation allowance	(37.50%)	(35.10%)	(11.80%)
Total	0.00%	0.00%	0.00%

Income Taxes - NOLs (Details)

Income Taxes - NOLs (Details)	Dec. 31, 2016USD ($)
Operating Loss Carryforwards [Line Items]
Maximum net operating losses and credit equivalents available for use in 2016	$ 201,900,000
Maximum net operating losses and credit equivalents available for use in 2017	16,800,000
Federal
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	212,363,000
State
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 273,989

Income Taxes - Net deferred tax

Income Taxes - Net deferred tax assets and liabilities (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets
Net operating loss carryforwards	$ 78,021,000	$ 73,678,000
Research and development credit carryforwards	14,143,000	12,398,000
Orphan drug credit	7,235,000	6,815,000
Stock options	7,105,000	5,568,000
Other	562,000	235,000
Deferred tax assets	107,066,000	98,694,000
Deferred tax liabilities
Deferred revenue		(8,049,000)
Property and equipment	(337,000)	(361,000)
Deferred tax liabilities	(337,000)	(8,410,000)
Net deferred tax asset before valuation allowance	106,729,000	90,284,000
Less valuation allowance	$ (106,729,000)	$ (90,284,000)

Income Taxes - Unrecognized tax

Income Taxes - Unrecognized tax benefits (Details)	12 Months Ended
	Dec. 31, 2016USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Additions based on tax positions related to the current year	$ 3,405,000
Balance at end of period	3,405,000
Uncertain tax liabilities that, if recognized, would affect the annual effective tax rate	$ 0

Collaborations (Details)

Collaborations (Details)	1 Months Ended		12 Months Ended	41 Months Ended
	Aug. 31, 2013USD ($)item	Apr. 30, 2012USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2016USD ($)	Feb. 28, 2011USD ($)	Mar. 01, 2010USD ($)	Dec. 31, 1995USD ($)
License Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Annual maintenance fees					$ 25,000
Minimum annual royalty payments due prior to commercial sales of product						$ 15,000	$ 12,500
Minimum annual royalty payments due after commercial sales of product begin						100,000
License Agreement | Research and Development Expense
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront fee paid					300,000
License Agreement | Completion Of Toxicology Studies In Compliance With Good Laboratory Practice Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payment for Milestone Achieved			$ 50,000
License Agreement | Dosing Of First Human Patient With P S M A Tubulysin Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payment for Milestone Achieved			100,000
License Agreement | Achievement Of Specific Scientific Clinical And Regulatory Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments to be paid					$ 5,900,000
License Agreement | Approval Of New Drug Application In US Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments to be paid						$ 500,000
Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received		$ 120,000,000
Milestone payment received		$ 5,000,000
Revenue recognized			70,300,000
Collaboration Agreement | License Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			52,700,000
Collaboration Agreement | Research And Development Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			$ 17,600,000
License And Commercialization Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received	$ 1,000,000
Revenue recognized				$ 0
Deferred Revenue				$ 800,000
Period of time for termination notice to be given prior to the first commercial sale in Japan	90 days
Period of time for termination notice to be given after the first commercial sale in Japan	6 months
Period of time for termination notice to be given after Company receives regulatory approval in Japan but fails to launch the product	6 months
License And Commercialization Agreement | Achievement Of Regulatory Goals For Etarfolatide In Five Different Cancer Indications Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of cancer indications required to be successfully achieved to receive additional milestone payments | item	5
License And Commercialization Agreement | Achievement Of Regulatory Goals For Etarfolatide In Five Different Cancer Indications Milestone | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments that could be received	$ 4,500,000
License And Commercialization Agreement | Commencement Of Clinical Trials In Japan For Specific And Nonspecific Indications And Filing For Approval In Japan For Specific And Nonspecific Indications Milestone | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments that could be received	$ 4,500,000

Related-Party Transactions (Det

Related-Party Transactions (Details) - USD ($)	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2011
Related Party Transaction [Line Items]
Research and Development Expense		$ 8,188	$ 5,985	$ 6,788	$ 6,531	$ 6,386	$ 6,582	$ 6,724	$ 6,617	$ 27,492,185	$ 26,309,475	$ 41,649,389
Operating Leases, Rent Expense, Net, Total										743,323	736,249	866,768
Purdue Research Foundation
Related Party Transaction [Line Items]
Research and Development Expense										1,069,000	1,000,000	1,000,000
Operating Leases, Rent Expense, Net, Total										597,000	588,000	592,000
Accounts Payable and Other Accrued Liabilities		$ 182,000								182,000
On Target
Related Party Transaction [Line Items]
Proceeds from License Fees Received	$ 191,000
License and Maintenance Revenue										20,000	20,000	20,000
On Target | Research and Development Expense
Related Party Transaction [Line Items]
Reimbursement Revenue										$ 14,397	$ 21,044	$ 50,614
On Target | Patents [Member]
Related Party Transaction [Line Items]
Reimbursement Revenue													$ 50,000

Retirement Plans (Details)

Retirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0.3	$ 0.3	$ 0.3

Restructuring Costs - accruals

Restructuring Costs - accruals (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Balance at beginning of period	$ 46,600	$ 1,300,000	$ 0
Charges during the period	(15,800)	134,000	5,400,000
Amounts paid during the period	(30,800)	(1,387,400)	(4,100,000)
Balance at end of period	0	46,600	1,300,000
Employee And Contract Termination
Balance at beginning of period	0	0	0
Charges during the period	0	0	1,300,000
Amounts paid during the period	0	0	(1,300,000)
Balance at end of period	0	0	0
Proceed Trial Termination
Balance at beginning of period	46,600	1,300,000	0
Charges during the period	(15,800)	134,000	4,100,000
Amounts paid during the period	(30,800)	(1,387,400)	(2,800,000)
Balance at end of period	$ 0	$ 46,600	$ 1,300,000

Selected Quarterly Financial 58

Selected Quarterly Financial Data (unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Abstract]
Revenues	$ 12	$ 33	$ 13	$ 12	$ 12	$ 33	$ 13	$ 12	$ 70,000	$ 70,000	$ 70,353,483
Operating Expenses [Abstract]
Research and development	8,188	5,985	6,788	6,531	6,386	6,582	6,724	6,617	27,492,185	26,309,475	41,649,389
General and administrative	3,096	2,988	7,394	3,820	3,527	3,776	4,071	4,360	17,298,139	15,733,462	23,677,366
Loss from operations	(11,272)	(8,940)	(14,169)	(10,339)	(9,901)	(10,325)	(10,782)	(10,965)	(44,720,324)	(41,972,937)	5,026,728
Interest income, net	232	232	208	189	162	153	185	152	861,212	651,543	577,447
Other expense, net	(25)		(1)	(3)	(55)	170	(7)	(57)	(28,461)	51,645	(144,698)
Net income (loss)	$ (11,065)	$ (8,708)	$ (13,962)	$ (10,153)	$ (9,794)	$ (10,002)	$ (10,604)	$ (10,870)	$ (43,887,573)	$ (41,269,749)	$ 5,459,477
Net loss per share -basic and diluted (in dollars per share)	$ (0.26)	$ (0.21)	$ (0.33)	$ (0.24)	$ (0.23)	$ (0.24)	$ (0.25)	$ (0.26)
Weighted average common shares outstanding - basic and diluted (in shares)	42,289,453	42,263,311	42,178,537	42,109,828	41,984,763	41,974,518	41,939,052	41,857,905