Endocyte (ECYT) 10-K 8 Mar 16 2015 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Feb. 29, 2016	Jun. 30, 2015
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
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			$ 150.8
Trading Symbol	ECYT
Entity Common Stock, Shares Outstanding		42,152,733

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 15,431,622	$ 45,533,443
Short-term investments	158,168,832	79,536,211
Receivables	8,678	706,403
Prepaid expenses	772,579	609,771
Other assets	493,863	652,510
Total current assets	174,875,574	127,038,338
Long-term investments	0	81,761,177
Property and equipment, net	3,398,398	3,970,665
Other noncurrent assets	111,605	31,194
Total assets	178,385,577	212,801,374
Current liabilities:
Accounts payable	1,262,565	1,234,759
Accrued wages and benefits	3,272,237	2,567,924
Accrued clinical trial expenses	804,066	2,336,645
Accrued expenses and other liabilities	850,125	745,668
Total current liabilities	6,188,993	6,884,996
Other liabilities, net of current portion	18,503	30,316
Deferred revenue, net of current portion	831,944	881,944
Total liabilities	7,039,440	7,797,256
Stockholders' equity:
Common stock: $0.001 par value, 100,000,000 shares authorized; 41,784,692 and 42,034,733 shares issued and outstanding at December 31, 2014 and 2015	42,035	41,785
Additional paid-in capital	381,118,489	373,571,500
Accumulated other comprehensive income	(79,399)	(143,928)
Retained deficit	(209,734,988)	(168,465,239)
Total stockholders’ equity	171,346,137	205,004,118
Total liabilities and stockholders’ equity	$ 178,385,577	$ 212,801,374

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
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	42,034,733	41,784,692
Common stock, shares outstanding	42,034,733	41,784,692

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Collaboration revenue	$ 70,000	$ 70,353,483	$ 64,870,919
Total revenue	70,000	70,353,483	64,870,919
Operating expenses:
Research and development	26,309,475	41,649,389	57,898,971
General and administrative	15,733,462	23,677,366	25,313,731
Total operating expenses	42,042,937	65,326,755	83,212,702
Income (loss) from operations	(41,972,937)	5,026,728	(18,341,783)
Other income (expense), net:
Interest income, net	651,543	577,447	463,047
Other income (expense), net	51,645	(144,698)	(153,702)
Net income (loss)	$ (41,269,749)	$ 5,459,477	$ (18,032,438)
Net income (loss) per share - basic (in dollars per share)	$ (0.98)	$ 0.14	$ (0.5)
Net income (loss) per share - diluted (in dollars per share)	$ (0.98)	$ 0.13	$ (0.5)
Items included in other comprehensive income (loss):
Unrealized gain (loss) and amounts reclassified to net income (loss) on foreign currency translation	$ 50,592	$ (38,776)	$ (6,805)
Unrealized gain (loss) on available-for-sale securities	13,937	(161,843)	(9,253)
Other comprehensive income (loss)	64,529	(200,619)	(16,058)
Comprehensive income (loss)	$ (41,205,220)	$ 5,258,858	$ (18,048,496)
Weighted-average number of common shares used in net income (loss) per share calculation - basic (in shares)	41,939,504	40,242,352	36,036,996
Weighted-average number of common shares used in net income (loss) per share calculation - diluted (in shares)	41,939,504	41,758,101	36,036,996

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]
Balances at Dec. 31, 2012	$ 99,573,278	$ 35,919	$ 255,356,888	$ 72,749	$ (155,892,278)
Balances (in shares) at Dec. 31, 2012		35,919,019
Exercise of stock options	644,934	$ 189	644,745	0	0
Exercise of stock options (in shares)		188,699
Exercise of warrants	0	$ 48	(48)	0	0
Exercise of warrants (in shares)		47,791
Stock-based compensation	6,059,005	$ 0	6,059,005	0	0
Net income (loss)	(18,032,438)	0	0	0	(18,032,438)
Unrealized gain (loss) and net realized loss (gain) reclassified to net income (loss) on foreign currency translation	(6,805)	0	0	(6,805)	0
Unrealized gain (loss) on securities	(9,253)	0	0	(9,253)	0
Balances at Dec. 31, 2013	88,228,721	$ 36,156	262,060,590	56,691	(173,924,716)
Balances (in shares) at Dec. 31, 2013		36,155,509
Exercise of stock options	1,290,886	$ 400	1,290,486	0	0
Exercise of stock options (in shares)		399,654
Stock-based compensation	8,021,447	$ 1	8,021,446	0	0
Stock-based compensation (in shares)		1,279
Employee stock purchase plan	299,229	$ 53	299,176	0	0
Employee stock purchase plan (in shares)		53,250
Issuance of common stock in connection with secondary offering	101,904,977	$ 5,175	101,899,802	0	0
Issuance of common stock in connection with secondary offering (in shares)		5,175,000
Net income (loss)	5,459,477	$ 0	0	0	5,459,477
Unrealized gain (loss) and net realized loss (gain) reclassified to net income (loss) on foreign currency translation	(38,776)	0	0	(38,776)	0
Unrealized gain (loss) on securities	(161,843)	0	0	(161,843)	0
Balances at Dec. 31, 2014	205,004,118	$ 41,785	373,571,500	(143,928)	(168,465,239)
Balances (in shares) at Dec. 31, 2014		41,784,692
Exercise of stock options	379,290	$ 146	379,144
Exercise of stock options (in shares)		146,046
Stock-based compensation	6,862,946	$ 29	6,862,917
Stock-based compensation (in shares)		29,190
Employee stock purchase plan	305,003	$ 75	304,928
Employee stock purchase plan (in shares)		74,805
Net income (loss)	(41,269,749)				(41,269,749)
Unrealized gain (loss) and net realized loss (gain) reclassified to net income (loss) on foreign currency translation	50,592			50,592
Unrealized gain (loss) on securities	13,937	$ 0	0	13,937	0
Balances at Dec. 31, 2015	$ 171,346,137	$ 42,035	$ 381,118,489	$ (79,399)	$ (209,734,988)
Balances (in shares) at Dec. 31, 2015		42,034,733

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities
Net income (loss)	$ (41,269,749)	$ 5,459,477	$ (18,032,438)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation	886,710	857,055	674,725
Stock-based compensation	6,920,220	8,025,261	6,059,005
Loss on disposal of property and equipment	10,639	6,100	1,778
Accretion of bond premium	1,310,238	1,615,063	1,246,143
Net realized foreign currency translation loss	51,944	0	0
Change in operating assets and liabilities:
Receivables	856,372	5,490,605	(2,508,687)
Prepaid expenses and other assets	(96,582)	2,711,331	2,016,928
Accounts payable	(60,713)	(3,700,175)	(386,241)
Accrued wages, benefits and other liabilities	(777,204)	(2,923,537)	1,337,021
Deferred revenue	(50,000)	(59,746,948)	(41,488,719)
Net cash used in operating activities	(32,218,125)	(42,205,768)	(51,080,485)
Investing activities
Purchases of property and equipment	(341,616)	(1,501,744)	(827,839)
Proceeds from disposal of property and equipment	0	10,000	0
Purchases of investments	(86,281,946)	(149,370,678)	(125,026,602)
Proceeds from sale and maturities of investments	88,114,199	82,302,191	195,146,871
Net cash provided by (used in) investing activities	1,490,637	(68,560,231)	69,292,430
Financing activities
Stock repurchase	(57,274)	(3,814)	0
Proceeds from public offering	0	101,904,977	0
Proceeds from the exercise of stock options	379,290	1,290,886	644,934
Proceeds from stock purchases under employee stock purchase plan	305,003	299,229	0
Net cash provided by financing activities	627,019	103,491,278	644,934
Effect of exchange rate	(1,352)	(38,776)	(6,805)
Net increase (decrease) in cash and cash equivalents	(30,101,821)	(7,313,497)	18,850,074
Cash and cash equivalents at beginning of period	45,533,443	52,846,940	33,996,866
Cash and cash equivalents at end of period	$ 15,431,622	$ 45,533,443	$ 52,846,940

Nature of Business and Organiza

Nature of Business and Organization	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	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 is in the process of dissolving Endocyte Europe B.V., which should be completed in the first half of 2016 but was considered substantially liquidated at December 31, 2015. 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, 2015
Accounting Policies [Abstract]
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. 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 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 Multiple-Element Arrangements 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, supplies, 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 Stock-Based Compensation The Company accounts for its stock-based compensation pursuant to ASC Topic 718, Compensation — Stock Compensation 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 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 is in the process of dissolving Endocyte Europe, B.V., which should be completed in the first half of 2016 but was considered substantially liquidated at December 31, 2015. 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, 2015
Accounting Changes and Error Corrections [Abstract]
Accounting Changes and Error Corrections [Text Block]	3. New Accounting Pronouncements Recently Issued Accounting Standards In February 2016, the FASB issued ASU 2016-02, Leases Leases Determining Whether the Host Contract in a Hybrid Financial Instrument Issued in the Form of a Share Is More Akin to Debt or to Equity In August 2014, the FASB issued ASU 2014-15 (Subtopic 205-40), Presentation of Financial Statements — Going Concern In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers

Net Income (Loss) per Share

Net Income (Loss) per Share	12 Months Ended
	Dec. 31, 2015
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, 2013, 2014 and 2015, the following number of potential common stock equivalents were outstanding: Common stock equivalents Year Ended December 31, 2013 2014 2015 Outstanding common stock options 5,246,465 5,096,674 5,686,815 Outstanding warrants 34,647 34,647 34,647 Outstanding PRSUs 270,649 245,396 213,758 Outstanding RSUs — 161,439 351,414 Shares to be purchased under the ESPP — 2,894 4,236 Total 5,551,761 5,541,050 6,290,870 These common stock equivalents were excluded from the determination of diluted net loss per share for the years ended December 31, 2013 and December 31, 2015, 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 Outstanding common stock options 1,494,796 Outstanding warrants 5,433 Outstanding RSUs 14,128 Shares to be purchased under the ESPP 1,392 Total 1,515,749

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2015
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 Unrealized Net Accumulated Balance at December 31, 2012 $ (5,011 ) $ 77,760 $ 72,749 Unrealized loss (6,805 ) (4,203 ) (11,008 ) Net amount reclassified to net loss — (5,050 ) (5,050 ) Other comprehensive loss (6,805 ) (9,253 ) (16,058 ) Balance at December 31, 2013 $ (11,816 ) $ 68,507 $ 56,691 Unrealized loss (38,776 ) (165,285 ) (204,061 ) Net amount reclassified to net income — 3,442 3,442 Other comprehensive loss (38,776 ) (161,843 ) (200,619 ) Balance at December 31, 2014 $ (50,592 ) $ (93,336 ) $ (143,928 ) Unrealized gain (loss) (1,352 ) 18,841 17,489 Net amount reclassified to net loss 51,944 (4,904 ) 47,040 Other comprehensive income 50,592 13,937 64,529 Balance at December 31, 2015 $ — $ (79,399 ) $ (79,399 ) The assets and liabilities of foreign operations are translated into U.S. dollars using the current exchange rate. For those operations, changes in exchange rates generally do not affect cash flows, which results in translation adjustments being 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. Reclassifications Out of Accumulated Other Comprehensive Income (Loss) Amount Reclassified from Accumulated Affected Line Item in the Details about Accumulated Other Comprehensive Income (Loss) Components Year Ended Year Ended Year Ended Unrealized Net Gains (Losses) on Securities $ (5,050 ) $ 3,442 $ (4,904 ) Other income (expense) Foreign Currency Translation Losses — — 51,944 Other income (expense) Total Reclassifications for the Period $ (5,050 ) $ 3,442 $ 47,040

Investments

Investments	12 Months Ended
	Dec. 31, 2015
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 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 Level 2 Level 3 The fair value of the Company’s fixed income securities is based on a market approach using quoted market values. Description Cost Level 1 Level 2 Fair Value Cash Cash $ 6,068,579 $ 6,068,579 $ — $ 6,068,579 Cash equivalents Money market funds 39,464,864 39,464,864 — 39,464,864 Cash and cash equivalents $ 45,533,443 $ 45,533,443 $ — $ 45,533,443 Short-term investments (due within 1 year) U.S. government agency obligations $ 38,934,684 $ 38,928,806 $ — $ 38,928,806 Corporate obligations 40,659,036 — 40,607,405 40,607,405 Total short-term investments $ 79,593,720 $ 38,928,806 $ 40,607,405 $ 79,536,211 Long-term investments (due after 1 year through 2 years) U.S. government treasury obligations $ 38,626,279 $ 38,623,495 $ — $ 38,623,495 U.S. government agency obligations 35,223,450 35,203,355 — 35,203,355 Corporate obligations 7,947,275 — 7,934,327 7,934,327 Total long-term investments $ 81,797,004 $ 73,826,850 $ 7,934,327 $ 81,761,177 The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2015: Description Cost Level 1 Level 2 Fair Value Cash Cash $ 5,154,191 $ 5,154,191 $ — $ 5,154,191 Cash equivalents FDIC insured deposits and money market funds 10,277,431 10,277,431 — 10,277,431 Cash and cash equivalents $ 15,431,622 $ 15,431,622 $ — $ 15,431,622 Short-term investments (due within 1 year) U.S. government treasury obligations $ 73,593,081 $ 73,560,085 $ — $ 73,560,085 U.S. government agency obligations 55,702,099 55,670,043 — 55,670,043 Corporate obligations 28,953,051 — 28,938,704 28,938,704 Total short-term investments $ 158,248,231 $ 129,230,128 $ 28,938,704 $ 158,168,832 All securities held at December 31, 2014 and 2015, were classified as available-for-sale as defined by ASC 320. Total unrealized gross gains were $18,858 and $5,690 for the years ended December 31, 2014 and 2015, respectively. Total unrealized gross losses were $112,194 and $85,089 for the years ended December 31, 2014 and 2015, 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 $1,429 and $1,667 for the years ended December 31, 2014 and 2015, respectively. There were no total realized gross losses for the years ended December 31, 2014 or 2015.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2015
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, 2014 2015 Laboratory equipment 7 $ 5,828,045 $ 6,022,585 Office equipment and software 3 – 7 1,225,298 1,271,847 Leasehold improvements 7 400,018 408,153 Assets not in service 23,836 53,378 7,477,197 7,755,963 Less accumulated depreciation (3,506,532 ) (4,357,565 ) $ 3,970,665 $ 3,398,398 Assets not in service represent new laboratory equipment, computer equipment and software that were not installed and ready to use at December 31, 2014 and 2015. The total amount of depreciation expense for the years ended December 31, 2013, 2014 and 2015 were $674,725, $857,055 and $886,710, respectively.

Warrant

Warrant	12 Months Ended
	Dec. 31, 2015
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 in 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, 2015
Leases [Abstract]
Leases of Lessee Disclosure [Text Block]	9. Leases Future minimum lease payments for noncancellable operating leases as of December 31, 2015, are as follows: 2016 $ 751,710 2017 158,474 2018 26,677 2019 — 2020 — Thereafter — Total minimum lease payments $ 936,861 Rent expense for operating leases was $784,531, $866,768 and $736,249 for the years ended December 31, 2013, 2014 and 2015, respectively.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	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 8,071,563 and 9,742,563 shares of common stock authorized and reserved under these plans at December 31, 2014 and December 31, 2015, 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. Due to insufficient history as a public company, the Company is using the “simplified” method for “plain vanilla” options to estimate the expected term of the stock options 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 2013, 2014 and 2015 were determined using the following assumptions: Year Ended December 31, 2013 2014 2015 Weighted-average volatility 101.00 % 102.86 % 106.38 % Risk-free interest rate 1.31 % 1.98 % 1.55 % Weighted-average expected life (in years) 6.6 6.6 6.4 Dividend yield 0.00 % 0.00 % 0.00 % The resulting value of options granted was $9,188,595 and $4,884,534 for the years ended December 31, 2014 and 2015, respectively, which will be amortized into income over the remaining requisite service period. The Company recognized stock-based compensation cost, net of forfeitures, in the amount of $6,059,005, $8,025,261 and $6,920,220 for the years ended December 31, 2013, 2014 and 2015, respectively. Options Weighted-Average Weighted-Average Aggregate Outstanding at January 1, 2013 3,879,239 $ 4.96 Granted during year 1,566,062 10.79 Exercised during year (188,699 ) 3.42 Expired during year — — Forfeited during year (10,137 ) 6.04 Outstanding at December 31, 2013 5,246,465 $ 6.76 7.39 $ 22,002,357 Exercisable at December 31, 2013 2,269,438 4.59 5.73 13,968,005 Outstanding at January 1, 2014 5,246,465 6.76 Granted during year 1,065,386 10.54 Exercised during year (399,654 ) 3.23 Expired during year (244,121 ) 9.17 Forfeited during year (571,402 ) 10.49 Outstanding at December 31, 2014 5,096,674 $ 7.29 6.87 $ 6,329,518 Exercisable at December 31, 2014 2,695,278 5.89 5.68 4,986,059 Outstanding at January 1, 2015 5,096,674 7.29 Granted during year 1,126,672 5.23 Exercised during year (146,046 ) 2.60 Expired during year (156,160 ) 11.03 Forfeited during year (234,325 ) 8.05 Outstanding at December 31, 2015 5,686,815 $ 6.87 6.52 $ 1,432,306 Exercisable at December 31, 2015 3,391,069 6.46 5.37 1,333,875 The following is a rollforward of the Company’s nonvested stock options from January 1, 2013 to December 31, 2015. Options Weighted-Average Nonvested stock options at January 1, 2013 2,203,223 $ 4.24 Granted during year 1,566,062 8.76 Vested during year (782,121 ) 4.22 Forfeited during year (10,137 ) 4.58 Nonvested at December 31, 2013 2,977,027 $ 6.62 Nonvested stock options at January 1, 2014 2,977,027 $ 6.62 Granted during year 1,065,386 8.62 Vested during year (1,069,615 ) 6.61 Forfeited during year (571,402 ) 8.36 Nonvested at December 31, 2014 2,401,396 $ 7.07 Nonvested stock options at January 1, 2015 2,401,396 $ 7.07 Granted during year 1,126,672 4.34 Vested during year (997,997 ) 6.48 Forfeited during year (234,325 ) 6.37 Nonvested at December 31, 2015 2,295,746 $ 6.05 The total grant date value of stock options vested during 2013, 2014 and 2015 was $3,303,701, $7,072,923 and $6,467,294 respectively. As of December 31, 2014 and December 31, 2015, the total remaining unrecognized compensation cost, net of forfeitures, related to stock options granted was $11,092,519 and $8,574,033, respectively, which is expected to be recognized over weighted average periods of approximately 1.6 and 1.4 years, respectively. The intrinsic value of options exercised was $2,934,244 and $396,619 for the years ended December 31, 2014 and December 31, 2015, 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. Each unit represents an amount equal to one share of the Company’s common stock. The PRSUs will be earned, in whole or in part, based on performance and service conditions. The performance condition is based upon whether the Company receives regulatory approval to sell a therapeutic product, and the awards include a target number of PRSUs that will vest upon a First Commercial Approval, and a maximum number of PRSUs that will vest upon a Second Commercial Approval. Any earned PRSUs will vest fifty percent based on the performance condition of commercial approval and fifty percent one year thereafter to fulfill the service condition, which requires the employee to remain employed by the Company. As of December 31, 2015, the Company had 213,758 PRSU awards outstanding. The unrecorded stock compensation expense is based on number of units granted, less estimated forfeitures based on the Company’s historical forfeiture rate of 6.49%, and the closing market price of the Company’s common stock at the grant date. As of December 31, 2015, the performance condition of obtaining regulatory approval had not been achieved, therefore, no vesting had occurred. The awards are being accounted for under ASC 718, and compensation expense is to be recorded if the Company determines that it is probable that the performance conditions will be achieved. As of December 31, 2015, it was not probable that the performance conditions will be achieved, therefore, no compensation expense related to the PRSUs was recorded for the year ended December 31, 2015. Based on the performance conditions and the stage of development of our potential products, we have concluded that the performance conditions will not be achieved before the performance deadline of May 26, 2016, and, as a result, we do not expect to recognize any stock-based compensation expense related to the PRSUs. 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, 2015, the Company had 351,414 RSU awards outstanding. As of December 31, 2014 and 2015, the total remaining unrecognized compensation cost, net of forfeitures, related to RSUs was $1.3 million and $1.6 million, respectively, which is expected to be recognized over a weighted average period of approximately 2.0 and 1.5 years, respectively. The following table sets forth the number of RSUs that were granted, vested and forfeited in the period indicated: Restricted Weighted-Average Outstanding at January 1, 2014 — $ — Granted during year 196,710 11.11 Vested during year (1,875 ) 11.11 Forfeited during year (33,396 ) 11.11 Outstanding at December 31, 2014 161,439 $ 11.11 Outstanding at January 1, 2015 161,439 $ 11.11 Granted during year 260,976 5.17 Vested during year (40,333 ) 11.11 Forfeited during year (30,668 ) 8.07 Outstanding at December 31, 2015 351,414 $ 7.03 Employee Stock Purchase Plan Effective January 1, 2014, the Company implemented the ESPP. At January 1, 2015, 986,530 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, 2015, plan participants purchased 74,805 shares of common stock under the ESPP at an average purchase price of $4.08 per share. At December 31, 2015, 911,725 shares were available for issuance under the ESPP.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	11. Income Taxes December 31, 2013 2014 2015 Income tax computed at federal statutory tax rate 34.0 % 34.0 % 34.0 % State taxes, net of federal benefit 4.2 % 6.3 % 3.2 % State taxes rate change, net of federal benefit — 30.4 % — International operations (2.1 )% 6.6 % (4.8 )% Research and development credits 13.8 % (22.6 )% 3.8 % Orphan drug credits 6.6 % (57.4 )% 0.9 % Equity compensation (2.5 )% 16.6 % (2.0 )% Other (1.3 )% (2.1 )% — Change in valuation allowance (52.7 )% (11.8 )% (35.1 )% Total 0.0 % 0.0 % 0.0 % At December 31, 2015, the Company had net operating loss carryforwards totaling approximately $191,146,000 and $247,018,000 for federal and state income taxes, respectively, that may be used to offset future taxable income. If not used, the carryforwards 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 $172,200,000 for 2015, $29,700,000 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. December 31, 2014 2015 Deferred tax assets Net operating loss carryforwards $ 71,074,000 $ 73,678,000 Research and development credit carryforwards 10,836,000 12,398,000 Orphan Drug Credit 6,286,000 6,815,000 Stock options 4,103,000 5,568,000 Other 202,000 235,000 Deferred tax assets 92,501,000 98,694,000 Deferred tax liabilities Deferred revenue (16,408,000 ) (8,049,000 ) Property and equipment (316,000 ) (361,000 ) Deferred tax liabilities $ (16,724,000 ) $ (8,410,000 ) Net deferred tax asset before valuation allowance $ 75,777,000 $ 90,284,000 Less valuation allowance (75,777,000 ) (90,284,000 ) Net deferred tax assets $ — $ —

Collaborations

Collaborations	12 Months Ended
	Dec. 31, 2015
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 2013, the Company paid $100,000 for dosing the first human patient with folate tubulysin. 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 to be paid in the first quarter of 2016 as an additional milestone will not be 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 $64.9 and $70.3 million of revenue related to the Merck collaboration during 2013 and 2014, respectively. 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 years ended December 31, 2013 and 2014, license revenue was approximately $51.5 and $52.7 million, respectively, while research and development services revenue was approximately $13.4 and $17.6 million, respectively, 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 preclinical 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 $0.9 million at December 31, 2015. 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, 2015
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 $824,559, $1,000,000 and $1,000,000 for the years ended December 31, 2013, 2014 and 2015, 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, 2016 with an option to extend the term. The amounts paid to Purdue Research Foundation related to the lease of this facility were $546,000, $592,000 and $588,000 for the years ended December 31, 2013, 2014, and 2015, respectively. At December 31, 2015, the Company had a balance of $235,000 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 2013, 2014 and 2015, and received $27,394, $50,614 and $21,044 for reimbursable research and development expenses, for 2013, 2014 and 2015, respectively.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2015
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 and 2015, 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, 2015
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 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 Vivian Oh Revocable Trust, Individually and on Behalf of All Others Situated v. Endocyte, Inc. and P. Ron Ellis Gopichand Vallabhaneni v. Endocyte, Inc. and P. Ron Ellis Lead Plaintiff seeks the designation of the Vallabhaneni Litigation as a class action, an award of unspecified damages, interest, costs, expert fees and attorneys’ fees, and equitable/injunctive relief or other relief as the court may deem just and proper. Pursuant to a December 9, 2014 order, all Defendants filed a motion to dismiss on March 6, 2015. Lead Plaintiff filed a motion in opposition on April 6, 2015 to which Defendants replied on April 20, 2015. 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. The Company believes that this lawsuit is without merit and has defended, and intends to continue to defend, itself vigorously against the allegations made in the Amended Complaint. On September 23, 2014, a complaint in a shareholder derivative lawsuit was filed against all of the Company’s current 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. On October 31, 2014, a complaint in a shareholder derivative lawsuit nearly identical to the Moore Litigation was filed against all of the Company’s current 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. 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 On November 6, 2014, a complaint was filed against the Company, two of its 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 Company also has certain obligations to indemnify, and advance expenses to, its directors and officers in connection with various actions, suits and proceedings.

Restructuring Costs

Restructuring Costs	12 Months Ended
	Dec. 31, 2015
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. At December 31, 2015, the Company had a clinical trial accrual balance related to the PROCEED trial termination of $46,600, which is expect to be fully paid in 2016. The following tables summarize the restructuring accruals for the years ended December 31, 2014 and 2015: Employee and PROCEED Total Balance, January 1, 2014 $ — $ — $ — Charges for the year ended December 31, 2014 1,300,000 4,100,000 5,400,000 Amounts paid in the year ended December 31, 2014 (1,300,000 ) (2,800,000 ) (4,100,000 ) Balance, December 31, 2014 $ — $ 1,300,000 $ 1,300,000 Balance, January 1, 2015 $ — $ 1,300,000 $ 1,300,000 Revised estimates in the year ended December 31, 2015 — 134,000 134,000 Amounts paid in the year ended December 31, 2015 — (1,387,400 ) (1,387,400 ) Balance, December 31, 2015 $ — $ 46,600 $ 46,600

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	17. Selected Quarterly Financial Data (unaudited) Quarters Ended March 31 June 30 September 30 December 31 2015 Revenue $ 12 $ 13 $ 33 $ 12 Operating Expenses: Research and development 6,617 6,724 6,582 6,386 General and administrative 4,360 4,071 3,776 3,527 Loss from operations (10,965 ) (10,782 ) (10,325 ) (9,901 ) Interest income, net 152 185 153 162 Other (57 ) (7 ) 170 (55 ) Net loss $ (10,870 ) $ (10,604 ) $ (10,002 ) $ (9,794 ) Net loss per share-basic and diluted (1)(2) $ (0.26 ) $ (0.25 ) $ (0.24 ) $ (0.23 ) Weighted average common shares outstanding – basic and diluted (2) 41,857,905 41,939,052 41,974,518 41,984,763 Quarters Ended March 31 June 30 September 30 December 31 2014 Revenue $ 17,269 $ 49,168 $ 3,904 $ 12 Operating Expenses: Research and development 12,987 18,990 5,675 3,998 General and administrative 7,501 7,968 4,007 4,201 Income (loss) from operations (3,219 ) 22,210 (5,778 ) (8,187 ) Interest income, net 85 168 161 164 Other (7 ) (22 ) (58 ) (58 ) Net income (loss) $ (3,141 ) $ 22,356 $ (5,675 ) $ (8,081 ) Basic net income (loss) per share (1) $ (0.09 ) $ 0.54 $ (0.14 ) $ (0.19 ) Diluted net income (loss) per share (1) $ (0.09 ) $ 0.52 $ (0.14 ) $ (0.19 ) Weighted average common shares outstanding – basic 36,193,942 41,398,251 41,564,840 41,736,930 Weighted average common shares outstanding – diluted 36,193,942 43,196,754 41,564,840 41,736,930 (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 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, 2015
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The accompanying consolidated financial statements include the accounts of Endocyte, Inc. and its subsidiaries and all intercompany amounts have been eliminated. 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, Policy [Policy Text Block]	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, Policy [Policy Text Block]	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.
Investment, Policy [Policy Text Block]	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
Property, Plant and Equipment, Policy [Policy Text Block]	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 [Policy Text Block]	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.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	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.
Lease, Policy [Policy Text Block]	Leases The Company evaluates all leases to determine whether they should be accounted for as operating or capital leases.
Revenue Recognition, Policy [Policy Text Block]	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 Multiple-Element Arrangements 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, Policy [Policy Text Block]	Research and Development Expenses Research and development expenses represent costs associated with the ongoing development of SMDCs and companion imaging agents and include salaries, supplies, 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
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Stock-Based Compensation The Company accounts for its stock-based compensation pursuant to ASC Topic 718, Compensation — Stock Compensation
Earnings Per Share, Policy [Policy Text Block]	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.
Regulatory Income Taxes, Policy [Policy Text Block]	Income Taxes The Company accounts for income taxes under the liability method in accordance with the provision of ASC Topic 740, Income Taxes 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 Reporting, Policy [Policy Text Block]	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 is in the process of dissolving Endocyte Europe, B.V., which should be completed in the first half of 2016 but was considered substantially liquidated at December 31, 2015. 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, 2015
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	As of December 31, 2013, 2014 and 2015, the following number of potential common stock equivalents were outstanding: Common stock equivalents Year Ended December 31, 2013 2014 2015 Outstanding common stock options 5,246,465 5,096,674 5,686,815 Outstanding warrants 34,647 34,647 34,647 Outstanding PRSUs 270,649 245,396 213,758 Outstanding RSUs — 161,439 351,414 Shares to be purchased under the ESPP — 2,894 4,236 Total 5,551,761 5,541,050 6,290,870
Schedule of Weighted Average Number of Shares [Table Text Block]	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 Outstanding common stock options 1,494,796 Outstanding warrants 5,433 Outstanding RSUs 14,128 Shares to be purchased under the ESPP 1,392 Total 1,515,749

Other Comprehensive Income (L26

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2015
Other Comprehensive Income (Loss), Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The accumulated balances related to each component of other comprehensive income (loss) were as follows: Foreign Unrealized Net Accumulated Balance at December 31, 2012 $ (5,011 ) $ 77,760 $ 72,749 Unrealized loss (6,805 ) (4,203 ) (11,008 ) Net amount reclassified to net loss — (5,050 ) (5,050 ) Other comprehensive loss (6,805 ) (9,253 ) (16,058 ) Balance at December 31, 2013 $ (11,816 ) $ 68,507 $ 56,691 Unrealized loss (38,776 ) (165,285 ) (204,061 ) Net amount reclassified to net income — 3,442 3,442 Other comprehensive loss (38,776 ) (161,843 ) (200,619 ) Balance at December 31, 2014 $ (50,592 ) $ (93,336 ) $ (143,928 ) Unrealized gain (loss) (1,352 ) 18,841 17,489 Net amount reclassified to net loss 51,944 (4,904 ) 47,040 Other comprehensive income 50,592 13,937 64,529 Balance at December 31, 2015 $ — $ (79,399 ) $ (79,399 )
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	Reclassifications Out of Accumulated Other Comprehensive Income (Loss) Amount Reclassified from Accumulated Affected Line Item in the Details about Accumulated Other Comprehensive Income (Loss) Components Year Ended Year Ended Year Ended Unrealized Net Gains (Losses) on Securities $ (5,050 ) $ 3,442 $ (4,904 ) Other income (expense) Foreign Currency Translation Losses — — 51,944 Other income (expense) Total Reclassifications for the Period $ (5,050 ) $ 3,442 $ 47,040

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Schedule Of Cash And Cash Equivalents And Short Term And Long Term Investments [Table Text Block]	The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2014: Description Cost Level 1 Level 2 Fair Value Cash Cash $ 6,068,579 $ 6,068,579 $ — $ 6,068,579 Cash equivalents Money market funds 39,464,864 39,464,864 — 39,464,864 Cash and cash equivalents $ 45,533,443 $ 45,533,443 $ — $ 45,533,443 Short-term investments (due within 1 year) U.S. government agency obligations $ 38,934,684 $ 38,928,806 $ — $ 38,928,806 Corporate obligations 40,659,036 — 40,607,405 40,607,405 Total short-term investments $ 79,593,720 $ 38,928,806 $ 40,607,405 $ 79,536,211 Long-term investments (due after 1 year through 2 years) U.S. government treasury obligations $ 38,626,279 $ 38,623,495 $ — $ 38,623,495 U.S. government agency obligations 35,223,450 35,203,355 — 35,203,355 Corporate obligations 7,947,275 — 7,934,327 7,934,327 Total long-term investments $ 81,797,004 $ 73,826,850 $ 7,934,327 $ 81,761,177 The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2015: Description Cost Level 1 Level 2 Fair Value Cash Cash $ 5,154,191 $ 5,154,191 $ — $ 5,154,191 Cash equivalents FDIC insured deposits and money market funds 10,277,431 10,277,431 — 10,277,431 Cash and cash equivalents $ 15,431,622 $ 15,431,622 $ — $ 15,431,622 Short-term investments (due within 1 year) U.S. government treasury obligations $ 73,593,081 $ 73,560,085 $ — $ 73,560,085 U.S. government agency obligations 55,702,099 55,670,043 — 55,670,043 Corporate obligations 28,953,051 — 28,938,704 28,938,704 Total short-term investments $ 158,248,231 $ 129,230,128 $ 28,938,704 $ 158,168,832

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	Property and equipment consisted of the following: Estimated December 31, 2014 2015 Laboratory equipment 7 $ 5,828,045 $ 6,022,585 Office equipment and software 3 – 7 1,225,298 1,271,847 Leasehold improvements 7 400,018 408,153 Assets not in service 23,836 53,378 7,477,197 7,755,963 Less accumulated depreciation (3,506,532 ) (4,357,565 ) $ 3,970,665 $ 3,398,398

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Future minimum lease payments for noncancellable operating leases as of December 31, 2015, are as follows: 2016 $ 751,710 2017 158,474 2018 26,677 2019 — 2020 — Thereafter — Total minimum lease payments $ 936,861

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	The weighted-average value of the individual options granted during 2013, 2014 and 2015 were determined using the following assumptions: Year Ended December 31, 2013 2014 2015 Weighted-average volatility 101.00 % 102.86 % 106.38 % Risk-free interest rate 1.31 % 1.98 % 1.55 % Weighted-average expected life (in years) 6.6 6.6 6.4 Dividend yield 0.00 % 0.00 % 0.00 %
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	The Company’s stock option activity and related information are summarized as follows: Options Weighted-Average Weighted-Average Aggregate Outstanding at January 1, 2013 3,879,239 $ 4.96 Granted during year 1,566,062 10.79 Exercised during year (188,699 ) 3.42 Expired during year — — Forfeited during year (10,137 ) 6.04 Outstanding at December 31, 2013 5,246,465 $ 6.76 7.39 $ 22,002,357 Exercisable at December 31, 2013 2,269,438 4.59 5.73 13,968,005 Outstanding at January 1, 2014 5,246,465 6.76 Granted during year 1,065,386 10.54 Exercised during year (399,654 ) 3.23 Expired during year (244,121 ) 9.17 Forfeited during year (571,402 ) 10.49 Outstanding at December 31, 2014 5,096,674 $ 7.29 6.87 $ 6,329,518 Exercisable at December 31, 2014 2,695,278 5.89 5.68 4,986,059 Outstanding at January 1, 2015 5,096,674 7.29 Granted during year 1,126,672 5.23 Exercised during year (146,046 ) 2.60 Expired during year (156,160 ) 11.03 Forfeited during year (234,325 ) 8.05 Outstanding at December 31, 2015 5,686,815 $ 6.87 6.52 $ 1,432,306 Exercisable at December 31, 2015 3,391,069 6.46 5.37 1,333,875
Schedule of Nonvested Share Activity [Table Text Block]	The following is a rollforward of the Company’s nonvested stock options from January 1, 2013 to December 31, 2015. Options Weighted-Average Nonvested stock options at January 1, 2013 2,203,223 $ 4.24 Granted during year 1,566,062 8.76 Vested during year (782,121 ) 4.22 Forfeited during year (10,137 ) 4.58 Nonvested at December 31, 2013 2,977,027 $ 6.62 Nonvested stock options at January 1, 2014 2,977,027 $ 6.62 Granted during year 1,065,386 8.62 Vested during year (1,069,615 ) 6.61 Forfeited during year (571,402 ) 8.36 Nonvested at December 31, 2014 2,401,396 $ 7.07 Nonvested stock options at January 1, 2015 2,401,396 $ 7.07 Granted during year 1,126,672 4.34 Vested during year (997,997 ) 6.48 Forfeited during year (234,325 ) 6.37 Nonvested at December 31, 2015 2,295,746 $ 6.05 The following table sets forth the number of RSUs that were granted, vested and forfeited in the period indicated: Restricted Weighted-Average Outstanding at January 1, 2014 — $ — Granted during year 196,710 11.11 Vested during year (1,875 ) 11.11 Forfeited during year (33,396 ) 11.11 Outstanding at December 31, 2014 161,439 $ 11.11 Outstanding at January 1, 2015 161,439 $ 11.11 Granted during year 260,976 5.17 Vested during year (40,333 ) 11.11 Forfeited during year (30,668 ) 8.07 Outstanding at December 31, 2015 351,414 $ 7.03

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	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, 2013, 2014, and 2015: December 31, 2013 2014 2015 Income tax computed at federal statutory tax rate 34.0 % 34.0 % 34.0 % State taxes, net of federal benefit 4.2 % 6.3 % 3.2 % State taxes rate change, net of federal benefit — 30.4 % — International operations (2.1 )% 6.6 % (4.8 )% Research and development credits 13.8 % (22.6 )% 3.8 % Orphan drug credits 6.6 % (57.4 )% 0.9 % Equity compensation (2.5 )% 16.6 % (2.0 )% Other (1.3 )% (2.1 )% — Change in valuation allowance (52.7 )% (11.8 )% (35.1 )% Total 0.0 % 0.0 % 0.0 %
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	Net deferred tax assets and liabilities are comprised of the following: December 31, 2014 2015 Deferred tax assets Net operating loss carryforwards $ 71,074,000 $ 73,678,000 Research and development credit carryforwards 10,836,000 12,398,000 Orphan Drug Credit 6,286,000 6,815,000 Stock options 4,103,000 5,568,000 Other 202,000 235,000 Deferred tax assets 92,501,000 98,694,000 Deferred tax liabilities Deferred revenue (16,408,000 ) (8,049,000 ) Property and equipment (316,000 ) (361,000 ) Deferred tax liabilities $ (16,724,000 ) $ (8,410,000 ) Net deferred tax asset before valuation allowance $ 75,777,000 $ 90,284,000 Less valuation allowance (75,777,000 ) (90,284,000 ) Net deferred tax assets $ — $ —

Restructuring Costs (Tables)

Restructuring Costs (Tables)	12 Months Ended
	Dec. 31, 2015
Restructuring Costs [Abstract]
Restructuring and Related Costs [Table Text Block]	The following tables summarize the restructuring accruals for the years ended December 31, 2014 and 2015: Employee and PROCEED Total Balance, January 1, 2014 $ — $ — $ — Charges for the year ended December 31, 2014 1,300,000 4,100,000 5,400,000 Amounts paid in the year ended December 31, 2014 (1,300,000 ) (2,800,000 ) (4,100,000 ) Balance, December 31, 2014 $ — $ 1,300,000 $ 1,300,000 Balance, January 1, 2015 $ — $ 1,300,000 $ 1,300,000 Revised estimates in the year ended December 31, 2015 — 134,000 134,000 Amounts paid in the year ended December 31, 2015 — (1,387,400 ) (1,387,400 ) Balance, December 31, 2015 $ — $ 46,600 $ 46,600

Selected Quarterly Financial 33

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	Quarters Ended March 31 June 30 September 30 December 31 2015 Revenue $ 12 $ 13 $ 33 $ 12 Operating Expenses: Research and development 6,617 6,724 6,582 6,386 General and administrative 4,360 4,071 3,776 3,527 Loss from operations (10,965 ) (10,782 ) (10,325 ) (9,901 ) Interest income, net 152 185 153 162 Other (57 ) (7 ) 170 (55 ) Net loss $ (10,870 ) $ (10,604 ) $ (10,002 ) $ (9,794 ) Net loss per share-basic and diluted (1)(2) $ (0.26 ) $ (0.25 ) $ (0.24 ) $ (0.23 ) Weighted average common shares outstanding – basic and diluted (2) 41,857,905 41,939,052 41,974,518 41,984,763 Quarters Ended March 31 June 30 September 30 December 31 2014 Revenue $ 17,269 $ 49,168 $ 3,904 $ 12 Operating Expenses: Research and development 12,987 18,990 5,675 3,998 General and administrative 7,501 7,968 4,007 4,201 Income (loss) from operations (3,219 ) 22,210 (5,778 ) (8,187 ) Interest income, net 85 168 161 164 Other (7 ) (22 ) (58 ) (58 ) Net income (loss) $ (3,141 ) $ 22,356 $ (5,675 ) $ (8,081 ) Basic net income (loss) per share (1) $ (0.09 ) $ 0.54 $ (0.14 ) $ (0.19 ) Diluted net income (loss) per share (1) $ (0.09 ) $ 0.52 $ (0.14 ) $ (0.19 ) Weighted average common shares outstanding – basic 36,193,942 41,398,251 41,564,840 41,736,930 Weighted average common shares outstanding – diluted 36,193,942 43,196,754 41,564,840 41,736,930 (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 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 Textual) - USD ($)	Apr. 02, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Nature Of Business And Organization [Line Items]
Stock Issued During Period, Shares, New Issues	5,175,000
Proceeds from Issuance of Common Stock	$ 101,900,000	$ 0	$ 101,904,977	$ 0

Significant Accounting Polici35

Significant Accounting Policies (Details Textual) $ in Millions	Dec. 31, 2015USD ($)
Research and Development Arrangement [Member]
Significant Accounting Policies [Line Items]
Prepaid Expense and Other Assets, Noncurrent	$ 0.5

Net Income (Loss) per Share (De

Net Income (Loss) per Share (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	6,290,870	5,541,050	5,551,761
Outstanding common stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	5,686,815	5,096,674	5,246,465
Outstanding warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	34,647	34,647	34,647
Outstanding PRSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	213,758	245,396	270,649
Outstanding RSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	351,414	161,439	0
Shares to be purchased under the ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential Common Stock Equivalents, Outstanding	4,236	2,894	0

Net Income (Loss) per Share1(De

Net Income (Loss) per Share1(Details 1)	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 [Member]
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	1,494,796
Outstanding warrants [Member]
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	5,433
Outstanding RSUs [Member]
Weighted Average Number Diluted Shares Outstanding Adjustment [Line Items]
Total Weighted Average Outstanding Common Stock equivalents	14,128
Shares to be purchased under the ESPP [Member]
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) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign Currency Translation Gains (Losses), Beginning balance	$ (50,592)	$ (11,816)	$ (5,011)
Foreign Currency Translation Gains (Losses), Unrealized gain (loss)	(1,352)	(38,776)	(6,805)
Foreign Currency Translation Gains (Losses), Net amount reclassified to net income (loss)	51,944	0	0
Foreign Currency Translation Gains (Losses), Other comprehensive income (loss)	50,592	(38,776)	(6,805)
Foreign Currency Translation Gains (Losses), Ending balance	0	(50,592)	(11,816)
Unrealized Net Gains (Losses) on Securities, Beginning balance	(93,336)	68,507	77,760
Unrealized Net Gains (Losses) on Securities, Unrealized gain (loss)	18,841	(165,285)	(4,203)
Unrealized Net Gains (Losses) on Securities, Net amount reclassified to net income (loss)	(4,904)	3,442	(5,050)
Unrealized Net Gains (Losses) on Securities, Other comprehensive income (loss)	13,937	(161,843)	(9,253)
Unrealized Net Gains (Losses) on Securities, Ending balance	(79,399)	(93,336)	68,507
Accumulated Other Comprehensive Gains (Losses), Beginning balance	(143,928)	56,691	72,749
Accumulated Other Comprehensive Gains (Losses), Unrealized gain (loss)	17,489	(204,061)	(11,008)
Accumulated Other Comprehensive Gains (Losses), Net amount reclassified to net income (loss)	47,040	3,442	(5,050)
Accumulated Other Comprehensive Gains (Losses), Other comprehensive income (loss)	64,529	(200,619)	(16,058)
Accumulated Other Comprehensive Gains (Losses), Ending balance	$ (79,399)	$ (143,928)	$ 56,691

Other Comprehensive Income (L39

Other Comprehensive Income (Loss) (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Comprehensive Income Loss [Line Items]
Unrealized Net Gains (Losses) on Securities	$ (4,904)	$ 3,442	$ (5,050)
Foreign Currency Translation Losses	50,592	(38,776)	(6,805)
Total Reclassifications for the Period	47,040	3,442	(5,050)
Other Income (Expense) [Member]
Other Comprehensive Income Loss [Line Items]
Unrealized Net Gains (Losses) on Securities	(4,904)	3,442	(5,050)
Foreign Currency Translation Losses	$ 51,944	$ 0	$ 0

Investments (Details)

Investments (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash
Cash	$ 5,154,191	$ 6,068,579
Cash equivalents
Money market funds	10,277,431	39,464,864
Cash and cash equivalents	15,431,622	45,533,443	$ 52,846,940	$ 33,996,866
Short-term investments (due within 1 year)
Short-term investments, Fair Value	158,168,832	79,536,211
Short-term investments, Cost	158,248,231	79,593,720
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value	0	81,761,177
Long-term investments, Cost		81,797,004
U.S. government treasury obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	73,560,085
Short-term investments, Cost	73,593,081
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		38,623,495
Long-term investments, Cost		38,626,279
U.S. government agency obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	55,670,043	38,928,806
Short-term investments, Cost	55,702,099	38,934,684
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		35,203,355
Long-term investments, Cost		35,223,450
Corporate obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	28,938,704	40,607,405
Short-term investments, Cost	28,953,051	40,659,036
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		7,934,327
Long-term investments, Cost		7,947,275
Fair Value, Inputs, Level 1 [Member]
Cash
Cash	5,154,191	6,068,579
Cash equivalents
Money market funds	10,277,431	39,464,864
Cash and cash equivalents	15,431,622	45,533,443
Short-term investments (due within 1 year)
Short-term investments, Fair Value	129,230,128	38,928,806
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		73,826,850
Fair Value, Inputs, Level 1 [Member] | U.S. government treasury obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	73,560,085
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		38,623,495
Fair Value, Inputs, Level 1 [Member] | U.S. government agency obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	55,670,043	38,928,806
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		35,203,355
Fair Value, Inputs, Level 1 [Member] | Corporate obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	0	0
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		0
Fair Value, Inputs, Level 2 [Member]
Cash
Cash	0	0
Cash equivalents
Money market funds	0	0
Cash and cash equivalents	0	0
Short-term investments (due within 1 year)
Short-term investments, Fair Value	28,938,704	40,607,405
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		7,934,327
Fair Value, Inputs, Level 2 [Member] | U.S. government treasury obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	0
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		0
Fair Value, Inputs, Level 2 [Member] | U.S. government agency obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	0	0
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		0
Fair Value, Inputs, Level 2 [Member] | Corporate obligations [Member]
Short-term investments (due within 1 year)
Short-term investments, Fair Value	$ 28,938,704	40,607,405
Long-term investments (due after 1 year through 2 years)
Long-term investments, Fair Value		$ 7,934,327

Investments (Details Textual)

Investments (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Unrealized Gain on Securities	$ 5,690	$ 18,858
Unrealized Loss on Securities	85,089	112,194
Realized Gain on Securities	1,667	1,429
Realized Loss on Securities	$ 0	$ 0

Property and Equipment (Details

Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 7,755,963	$ 7,477,197
Less accumulated depreciation	(4,357,565)	(3,506,532)
Property, Plant and Equipment, Net	3,398,398	3,970,665
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6,022,585	5,828,045
Property, Plant and Equipment, Useful Life	7 years
Office equipment and software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,271,847	1,225,298
Office equipment and software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Office equipment and software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 408,153	400,018
Property, Plant and Equipment, Useful Life	7 years
Assets not in service [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 53,378	$ 23,836

Property and Equipment (Detai43

Property and Equipment (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Depreciation, Total	$ 886,710	$ 857,055	$ 674,725

Warrant (Details Textual)

Warrant (Details Textual) - $ / shares	12 Months Ended
	Dec. 31, 2007	Dec. 31, 2015
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		34,647
Common Stock [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 8.12
GECC And Oxford [Member]
Class of Warrant or Right [Line Items]
Warrants Maturity Date	2,017

Leases (Details)

Leases (Details)	Dec. 31, 2015USD ($)
Operating Leased Assets [Line Items]
2,016	$ 751,710
2,017	158,474
2,018	26,677
2,019	0
2,020	0
Thereafter	0
Total minimum lease payments	$ 936,861

Leases (Details Textual)

Leases (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense, Net, Total	$ 736,249	$ 866,768	$ 784,531

Stockholders' Equity (Details)

Stockholders' Equity (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Weighted-average volatility	106.38%	102.86%	101.00%
Risk-free interest rate	1.55%	1.98%	1.31%
Weighted-average expected life (in years)	6 years 4 months 24 days	6 years 7 months 6 days	6 years 7 months 6 days
Dividend yield	0.00%	0.00%	0.00%

Stockholders' Equity (Details 1

Stockholders' Equity (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Granted during year	1,126,672	1,065,386	1,566,062
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Outstanding, Beginning Balance	5,096,674	5,246,465	3,879,239
Options, Granted during year	1,126,672	1,065,386	1,566,062
Options, Exercised during year	(146,046)	(399,654)	(188,699)
Options, Expired during year	(156,160)	(244,121)	0
Options, Forfeited during year	(234,325)	(571,402)	(10,137)
Options, Outstanding, Ending Balance	5,686,815	5,096,674	5,246,465
Options, Exercisable	3,391,069	2,695,278	2,269,438
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 7.29	$ 6.76	$ 4.96
Weighted Average Exercise Price, Granted during year	5.23	10.54	10.79
Weighted Average Exercise Price, Exercised during year	2.6	3.23	3.42
Weighted average Exercise Price, Expired during year	11.03	9.17	0
Weighted Average Exercise Price, Forfeited during year	8.05	10.49	6.04
Weighted Average Exercise Price, Outstanding, Ending Balance	6.87	7.29	6.76
Weighted Average Exercise Price, Exercisable	$ 6.46	$ 5.89	$ 4.59
Weighted Average Remaining Contractual Term, Outstanding, Ending Balance	6 years 6 months 7 days	6 years 10 months 13 days	7 years 4 months 20 days
Weighted Average Remaining Contractual Term, Exercisable	5 years 4 months 13 days	5 years 8 months 5 days	5 years 8 months 23 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 1,432,306	$ 6,329,518	$ 22,002,357
Aggregate Intrinsic Value, Exercisable	$ 1,333,875	$ 4,986,059	$ 13,968,005

Stockholders' Equity (Details 2

Stockholders' Equity (Details 2) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Options, Nonvested stock options, Beginning Balance	2,401,396	2,977,027	2,203,223
Options, Granted during year	1,126,672	1,065,386	1,566,062
Options, Vested during year	(997,997)	(1,069,615)	(782,121)
Options, Forfeited during year	(234,325)	(571,402)	(10,137)
Options, Nonvested stock options, Ending Balance	2,295,746	2,401,396	2,977,027
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	$ 7.07	$ 6.62	$ 4.24
Weighted-Average Grant Date Value, Granted during year	4.34	8.62	8.76
Weighted-Average Grant Date Value, Vested during year	6.48	6.61	4.22
Weighted-Average Grant Date Value, Forfeited during year	6.37	8.36	4.58
Weighted-Average Grant Date Value, Nonvested stock options, Ending Balance	$ 6.05	$ 7.07	$ 6.62

Stockholders' Equity (Details 3

Stockholders' Equity (Details 3) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock Units [Abstract]
Restricted Stock Units, Outstanding, Beginning Balance	161,439	0
Restricted Stock Units, Granted during period	260,976	196,710
Restricted Stock Units, Vested during period	(40,333)	(1,875)
Restricted Stock Units, Forfeited during period	(30,668)	(33,396)
Restricted Stock Units, Outstanding, Ending Balance	351,414	161,439
Restricted Stock Units Weighted Average Grant Date Fair Value [Abstract]
Weighted-Average Grant Date Value, Outstanding, Beginning Balance	$ 11.11	$ 0
Weighted-Average Grant Date Value, Granted during period	5.17	11.11
Weighted-Average Grant Date Value, Vested during period	11.11	11.11
Weighted-Average Grant Date Value, Forfeited during period	8.07	11.11
Weighted-Average Grant Date Value, Outstanding, Ending Balance	$ 7.03	$ 11.11

Stockholders' Equity (Details T

Stockholders' Equity (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares Authorized	100,000,000	100,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	$ 8,574,033	$ 11,092,519
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 4 months 24 days	1 year 7 months 6 days
Stock Granted, Value, Share-based Compensation, Gross	$ 4,884,534	$ 9,188,595
Share-based Compensation, Total	6,920,220	8,025,261	$ 6,059,005
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	6,467,294	7,072,923	$ 3,303,701
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 396,619	$ 2,934,244
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 6 months	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Beginning Balance	351,414
Allocated Share-based Compensation Expense	$ 1,600,000	$ 1,300,000
Performance-based Restricted Stock Units (PRSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of Historical Forfeiture	6.49%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Beginning Balance	213,758
Equity Incentive Plan 2010 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares Authorized	9,742,563	8,071,563
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 4.08
Stock Issued During Period, Shares, Employee Stock Purchase Plans	74,805
Common Stock, Capital Shares Reserved for Future Issuance	911,725	986,530

Income Taxes (Details)

Income Taxes (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Income tax computed at federal statutory tax rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	3.20%	6.30%	4.20%
State taxes rate change, net of federal benefit	0.00%	30.40%	0.00%
International operations	(4.80%)	6.60%	(2.10%)
Research and development credits	3.80%	(22.60%)	13.80%
Orphan drug credits	0.90%	(57.40%)	6.60%
Equity compensation	(2.00%)	16.60%	(2.50%)
Other	0.00%	(2.10%)	(1.30%)
Change in valuation allowance	(35.10%)	(11.80%)	(52.70%)
Total	0.00%	0.00%	0.00%

Income Taxes (Details 1)

Income Taxes (Details 1) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets
Net operating loss carryforwards	$ 73,678,000	$ 71,074,000
Research and development credit carryforwards	12,398,000	10,836,000
Orphan Drug Credit	6,815,000	6,286,000
Stock options	5,568,000	4,103,000
Other	235,000	202,000
Deferred tax assets	98,694,000	92,501,000
Deferred tax liabilities
Deferred revenue	(8,049,000)	(16,408,000)
Property and equipment	(361,000)	(316,000)
Deferred tax liabilities	(8,410,000)	(16,724,000)
Net deferred tax asset before valuation allowance	90,284,000	75,777,000
Less valuation allowance	(90,284,000)	(75,777,000)
Net deferred tax assets	$ 0	$ 0

Income Taxes (Details Textual)

Income Taxes (Details Textual)	12 Months Ended
	Dec. 31, 2015USD ($)
Operating Loss Carryforwards [Line Items]
Operating Loss Carry Forward Expiration Period	2,021
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	$ 191,146,000
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	247,018,000
For 2014 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	172,200,000
For 2016 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	29,700,000
For 2017 [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 16,800,000

Collaborations (Details Textual

Collaborations (Details Textual) - USD ($)	Aug. 13, 2013	Apr. 30, 2012	Feb. 28, 2011	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2009	Dec. 31, 1995
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable Upfront Payments Received		$ 120,000,000
Collaboration Revenue												$ 70,000	$ 70,353,483	$ 64,870,919
Research and Development Expense			$ 300,000	$ 6,386,000	$ 6,582,000	$ 6,724,000	$ 6,617,000	$ 3,998,000	$ 5,675,000	$ 18,990,000	$ 12,987,000	26,309,475	41,649,389	57,898,971
Licenses Revenue													52,700,000	51,500,000
License and Services Revenue													17,600,000	13,400,000
Additional Contingent Payable Upon Satisfaction Of Certain Criteria				5,900,000								5,900,000
Minimum Annual Royalty Payments Payable Until First Commercial Sale																$ 12,500
Maintenance Costs			$ 25,000
Payments to Acquire in Process Research and Development		120,000,000
Future Milestone Payments															$ 500,000
Royalty Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Minimum Annual Royalty Payments Payable Until First Commercial Sale															15,000
Minimum Annual Royalty Milestone Payments															$ 100,000
NMP [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable Upfront Payments Received	$ 1,000,000
Deferred Revenue				$ 900,000								900,000
Potential Milestone Payments	$ 4,500,000											$ 4,500,000
Good Laboratory Practice [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payment for Milestone Achieved													50,000
PSMA tubulysin [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payment for Milestone Achieved													$ 100,000
Folate Tubulysin [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payment for Milestone Achieved														$ 100,000
Development Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable Upfront Payments Received		5,000,000
Non Substantive Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable Upfront Payments Received		$ 5,000,000

Related-Party Transactions (Det

Related-Party Transactions (Details Textual) - USD ($)	1 Months Ended	3 Months Ended								12 Months Ended
	Feb. 28, 2011	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Related Party Transaction [Line Items]
Research and Development Expense	$ 300,000	$ 6,386,000	$ 6,582,000	$ 6,724,000	$ 6,617,000	$ 3,998,000	$ 5,675,000	$ 18,990,000	$ 12,987,000	$ 26,309,475	$ 41,649,389	$ 57,898,971
Proceeds from License Fees Received													$ 191,000
License and Maintenance Revenue										20,000	20,000	20,000
Operating Leases, Rent Expense, Net, Total										736,249	866,768	784,531
Research and Development Expense [Member]
Related Party Transaction [Line Items]
Reimbursable Research And Development Expenses										21,044	50,614	27,394
Patents [Member]
Related Party Transaction [Line Items]
Reimbursement Revenue													$ 50,000
Chief Science Officer [Member]
Related Party Transaction [Line Items]
Research and Development Expense										1,000,000	1,000,000	824,559
Operating Leases, Rent Expense, Net, Total										588,000	$ 592,000	$ 546,000
Accounts Payable and Other Accrued Liabilities		$ 235,000								$ 235,000
Lease Expiration Date										Dec. 31, 2016

Retirement Plans (Details Textu

Retirement Plans (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0.3	$ 0.3

Restructuring Costs (Details)

Restructuring Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Balance, (Opening)	$ 1,300,000	$ 0
Charges During The Period	134,000	5,400,000
Amounts Paid During The Period	(1,387,400)	(4,100,000)
Balance, (Closing)	46,600	1,300,000
Employee and Contract Termination Accrual
Balance, (Opening)	0	0
Charges During The Period	0	1,300,000
Amounts Paid During The Period	0	(1,300,000)
Balance, (Closing)	0	0
PROCEED Trial Termination Accrual
Balance, (Opening)	1,300,000	0
Charges During The Period	134,000	4,100,000
Amounts Paid During The Period	(1,387,400)	(2,800,000)
Balance, (Closing)	$ 46,600	$ 1,300,000

Restructuring Costs (Details Te

Restructuring Costs (Details Textual)	Dec. 31, 2015USD ($)
PROCEED Trial Termination Accrual
Restructuring Cost and Reserve [Line Items]
Accrual Restructuring Cost Balance	$ 46,600

Selected Quarterly Financial 60

Selected Quarterly Financial Data (unaudited) (Details) - USD ($)		1 Months Ended	3 Months Ended												12 Months Ended
		Feb. 28, 2011	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Selected Quarterly Financial Data Unaudited [Line Items]
Revenue			$ 12,000	$ 33,000	$ 13,000	$ 12,000	$ 12,000		$ 3,904,000		$ 49,168,000		$ 17,269,000		$ 70,000	$ 70,353,483	$ 64,870,919
Operating expenses:
Research and development		$ 300,000	6,386,000	6,582,000	6,724,000	6,617,000	3,998,000		5,675,000		18,990,000		12,987,000		26,309,475	41,649,389	57,898,971
General and administrative			3,527,000	3,776,000	4,071,000	4,360,000	4,201,000		4,007,000		7,968,000		7,501,000		15,733,462	23,677,366	25,313,731
Income (loss) from operations			(9,901,000)	(10,325,000)	(10,782,000)	(10,965,000)	(8,187,000)		(5,778,000)		22,210,000		(3,219,000)		(41,972,937)	5,026,728	(18,341,783)
Interest income, net			162,000	153,000	185,000	152,000	164,000		161,000		168,000		85,000		651,543	577,447	463,047
Other			(55,000)	170,000	(7,000)	(57,000)	(58,000)		(58,000)		(22,000)		(7,000)		51,645	(144,698)	(153,702)
Net income (loss)			$ (9,794,000)	$ (10,002,000)	$ (10,604,000)	$ (10,870,000)	$ (8,081,000)		$ (5,675,000)		$ 22,356,000		$ (3,141,000)		$ (41,269,749)	$ 5,459,477	$ (18,032,438)
Basic net income (loss) per share (in dollars per share)							$ (0.19)	[1]	$ (0.14)	[1]	$ 0.54	[1]	$ (0.09)	[1]	$ (0.98)	$ 0.14	$ (0.5)
Diluted net income (loss) per share (in dollars per share)							$ (0.19)	[1]	$ (0.14)	[1]	$ 0.52	[1]	$ (0.09)	[1]	$ (0.98)	$ 0.13	$ (0.5)
Weighted average common shares outstanding - basic (in shares)							41,736,930		41,564,840		41,398,251		36,193,942		41,939,504	40,242,352	36,036,996
Weighted average common shares outstanding - diluted (in shares)							41,736,930		41,564,840		43,196,754		36,193,942		41,939,504	41,758,101	36,036,996
Basic and diluted net loss per share (in dollars per share)	[1],[2]		$ (0.23)	$ (0.24)	$ (0.25)	$ (0.26)
Weighted average common shares outstanding - basic and diluted (in shares)	[2]		41,984,763	41,974,518	41,939,052	41,857,905
[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 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.