Endocyte (ECYT) 10-Q 7 Nov 17 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Entity Registrant Name	ENDOCYTE INC
Entity Central Index Key	1,235,007
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		47,881,033

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents at carrying value	$ 47,178,505	$ 31,228,192
Short-term investments	55,901,729	106,979,224
Receivables	27,746	55,074
Prepaid expenses	1,159,139	1,737,308
Other assets	125,435	255,912
Total current assets	104,392,554	140,255,710
Property and equipment, net	2,445,550	3,205,077
Other noncurrent assets	7,067	33,567
Total assets	106,845,171	143,494,354
Current liabilities:
Accounts payable	395,046	1,381,545
Accrued wages and benefits	1,542,864	2,705,475
Accrued clinical trial expenses	1,360,587	861,293
Accrued expenses and other liabilities	1,048,764	613,861
Total current liabilities	4,347,261	5,562,174
Other liabilities, net of current portion		2,873
Deferred revenue, net of current portion	744,444	781,944
Total liabilities	5,091,705	6,346,991
Stockholders’ equity:
Common stock: $0.001 par value, 100,000,000 shares authorized; 42,377,522 and 42,859,381 shares issued and outstanding at December 31, 2016 and September 30, 2017	47,860	42,378
Additional paid-in capital	402,100,682	390,768,742
Accumulated other comprehensive (loss) income	(4,560)	(41,196)
Retained deficit	(300,390,516)	(253,622,561)
Total stockholders’ equity	101,753,466	137,147,363
Total liabilities and stockholders’ equity	$ 106,845,171	$ 143,494,354

CONDENSED BALANCE SHEETS (Paren

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	47,859,381	42,377,522
Common stock, shares outstanding	47,859,381	42,377,522

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue:
Collaboration revenue	$ 32,500	$ 32,500	$ 57,500	$ 57,500
Total revenue	32,500	32,500	57,500	57,500
Operating expenses:
Research and development	4,089,677	5,985,230	20,739,170	19,304,124
General and administrative	3,011,176	2,987,168	10,061,722	14,201,399
Acquired in-process research and development	16,493,132		16,493,132
Total operating expenses	23,593,985	8,972,398	47,294,024	33,505,523
Loss from operations	(23,561,485)	(8,939,898)	(47,236,524)	(33,448,023)
Other income (expense), net:
Interest income, net	264,932	232,240	734,065	629,289
Other income (expense), net	29,735	262	2,328	(4,062)
Net loss	$ (23,266,818)	$ (8,707,396)	$ (46,500,131)	$ (32,822,796)
Net loss per share -basic and diluted (in dollars per share)	$ (0.55)	$ (0.21)	$ (1.09)	$ (0.78)
Items included in other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	$ 30,303	$ (64,606)	$ 36,636	$ 111,039
Other comprehensive income (loss)	30,303	(64,606)	36,636	111,039
Comprehensive loss	$ (23,236,515)	$ (8,772,002)	$ (46,463,495)	$ (32,711,757)
Weighted-average number of common shares used in net loss per share calculation - basic and diluted (in shares)	42,636,567	42,263,311	42,525,693	42,184,182

CONDENSED STATEMENT OF STOCKHOL

CONDENSED STATEMENT OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($)	New Accounting Pronouncement Early Adoption EffectAdditional Paid-in Capital [Member]	New Accounting Pronouncement Early Adoption EffectRetained Earnings [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss)	Retained Earnings [Member]	Total
Balance at beginning of period at Dec. 31, 2015					$ (79,399)
Net income (loss)							$ (32,822,796)
Unrealized loss on securities							111,039
Balance at end of period at Sep. 30, 2016					31,640
Balance at beginning of period at Jun. 30, 2016					96,246
Net income (loss)							(8,707,396)
Unrealized loss on securities							(64,606)
Balance at end of period at Sep. 30, 2016					31,640
Reclassification of impact of ASU 2016-09 (See Note 3) | ASU 2016-09	$ 267,824	$ (267,824)
Balance after adjustment			$ 42,378	$ 391,036,566	(41,196)	$ (253,890,385)	137,147,363
Balance at beginning of period (Previously Reported) at Dec. 31, 2016			$ 42,378	390,768,742	(41,196)	(253,622,561)	137,147,363
Balance at beginning of period at Dec. 31, 2016					(41,196)		137,147,363
Balances (in shares) (Previously Reported) at Dec. 31, 2016			42,377,522
Balances (in shares) at Dec. 31, 2016			42,377,522
Exercise of stock options			$ 52	109,690			109,742
Exercise of stock options (in shares)			52,258
Stock-based compensation			$ 115	2,586,131			2,586,246
Stock-based compensation (in shares)			114,365
Employee stock purchase plan			$ 37	48,370			48,407
Issuance of common stock in connection with development and license agreement			$ 2,000	2,818,000			2,820,000
Issuance of common stock in connection with development and license agreement (in shares)			2,000,000
Issuance of common stock in connection with exercise of warrant to purchase common stock			$ 3,278	5,501,925			5,505,203
Issuance of common stock in connection with exercise of warrant to purchase common stock (in shares)			3,278,000
Number of shares purchased under ESPP			37,236
Net income (loss)						(46,500,131)	(46,500,131)
Unrealized loss on securities					36,636		36,636
Balance at end of period at Sep. 30, 2017			$ 47,860	402,100,682	(4,560)	(300,390,516)	$ 101,753,466
Balances (in shares) at Sep. 30, 2017			47,859,381
Balance at beginning of period at Jun. 30, 2017					(34,863)
Exercise of stock options (in shares)							0
Net income (loss)							$ (23,266,818)
Unrealized loss on securities							30,303
Balance at end of period at Sep. 30, 2017			$ 47,860	$ 402,100,682	$ (4,560)	$ (300,390,516)	$ 101,753,466
Balances (in shares) at Sep. 30, 2017			47,859,381

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net income (loss)	$ (46,500,131)	$ (32,822,796)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	701,133	679,675
Stock-based compensation	2,680,873	7,889,999
Acquired in-process research and development	16,493,132
Loss on disposal of property and equipment	114,042
Accretion of bond premium	1,399	331,881
Change in operating assets and liabilities:
Receivables	157,805	170,934
Prepaid expenses and other assets	770,892	(490,175)
Accounts payable	(1,160,801)	104,079
Accrued wages, benefits and other liabilities	(633,288)	(1,933,414)
Deferred revenue	(37,500)	(37,500)
Net cash used in operating activities	(27,412,444)	(26,107,317)
Investing activities
Purchases of property and equipment	(46,833)	(664,673)
Purchases of investments	(51,318,003)	(114,900,851)
Purchase of acquired in-process research and development	(12,322,349)
Proceeds from sale and maturities of investments	102,430,000	160,865,053
Net cash provided by investing activities	38,742,815	45,299,529
Financing activities
Stock repurchase	(94,627)	(158,283)
Proceeds from exercise of warrant to purchase common stock	4,556,420
Proceeds from the exercise of stock options	109,742	129,306
Proceeds from stock purchases under employee stock purchase plan	48,407	137,925
Net cash provided by financing activities	4,619,942	108,948
Net increase (decrease) in cash and cash equivalents	15,950,313	19,301,160
Cash and cash equivalents at beginning of period	31,228,192	15,431,622
Cash and cash equivalents at end of period	$ 47,178,505	$ 34,732,782

Nature of Business and Organiza

Nature of Business and Organization	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Organization	1. Nature of Business and Organization Endocyte, Inc. (the “Company”) is a biopharmaceutical company and leader in developing targeted therapies for the treatment of cancer. The Company uses drug conjugation technology to create novel therapeutics and companion imaging agents for personalized targeted therapies. The Company’s agents actively target receptors that are over-expressed on diseased cells relative to healthy cells, such as prostate specific membrane antigen (“PSMA”), in prostate cancer. This targeted approach is designed to safely enable the delivery of highly potent drug payloads. The companion imaging agents are designed to identify patients whose disease over-expresses the target of the therapy and who are therefore more likely to benefit from treatment. In June 2017, the Company ended clinical development of EC1456 and stopped enrollment in its EC1456 phase 1b trial as the assessment of trial data did not yield the level of clinical activity necessary to support continued advancement of EC1456. The Company is, however, continuing enrollment of a small number of patients in its EC1456 ovarian cancer surgical trial. In addition, in June 2017, the Company narrowed the focus of its EC1169 development program, refocused its efforts on pre-clinical programs, and reduced its workforce by approximately 40% to align resources to focus on the Company’s highest value opportunities while maintaining key capabilities. In September 2017, the Company entered into a Development and License Agreement (the “License Agreement’) with ABX advanced biochemical compounds – Biomedizinische Forschungsreagenzien GmbH (“ABX”), pursuant to which the Company acquired exclusive worldwide rights to develop and commercialize PSMA ‑ 617 agents, including the product candidate known as 177 Lu-PSMA ‑ 617, a radioligand therapeutic (“RLT”). The Company intends to seek regulatory approval to initiate, in the first half of 2018, a phase 3 clinical trial of 177 Lu-PSMA ‑ 617 in patients with metastatic castration-resistant prostate cancer (“mCRPC”).

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Basis of Presentation The accompanying condensed financial statements are prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) for interim financial information to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the accompanying condensed financial statements have been included. Interim results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2017 or any other future period. These condensed financial statements should be read in conjunction with the Company’s audited financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. Subsequent events have been evaluated through the date of issuance, which is the same as the date this Form 10-Q is filed with the Securities and Exchange Commission. 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. All long-lived assets are held in the U.S. The Company views its operations and manages its business in one operating segment. 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 money market instruments, U.S. government treasury obligations, corporate debt securities and repurchase agreements that are maintained by an investment manager. Investments Investments consist primarily of investments in U.S. Treasuries and corporate debt securities, which could also include commercial paper, that are maintained by an investment manager. Management determines the appropriate classification of marketable securities at the time of purchase and reevaluates such classification as of each balance sheet date. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities are included in other income. The Company considers and accounts for other-than-temporary impairments according to the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 320, Investments — Debt and Equity Securities (“ASC 320”). The cost of securities sold is based on the specific-identification method. Discounts and premiums on debt securities are amortized to interest income and expensed over the term of the security. Revenue Recognition The Company recognizes revenues from license and collaboration agreements when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the fee is fixed or determinable, and there is reasonable assurance that the related amounts are collectible in accordance with ASC Topic 605, Revenue Recognition (“ASC 605”). The Company’s license and collaboration agreements may contain multiple elements, including grants of licenses to intellectual property rights, agreement to provide research and development services and other deliverables. The deliverables under such arrangements are evaluated under ASC Subtopic 605-25, Multiple-Element Arrangements (“ASC 605-25”). Under ASC 605-25, each required deliverable is evaluated to determine whether it qualifies as a separate unit of accounting based on whether the deliverable has “stand-alone value” to the customer. The arrangement’s consideration that is fixed or determinable, excluding contingent milestone payments and royalties, is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. In general, the consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. Upfront payments for licensing the Company’s intellectual property are evaluated to determine if the licensee can obtain stand-alone value from the license separate from the value of the research and development services and other deliverables in the arrangement to be provided by the Company. If at the inception of an arrangement the Company determines that the license does not have stand-alone value separate from the research and development services or other deliverables, the license, services and other deliverables are combined as one unit of account and upfront payments are recorded as deferred revenue on the balance sheet and are recognized in a manner consistent with the final deliverable. Subsequent to the inception of an arrangement, the Company evaluates the remaining deliverables for separation as items in the arrangement are delivered. When stand-alone value is identified, the related consideration is recorded as revenue in the period in which the license or other intellectual property rights are delivered. In those circumstances where research and development services or other deliverables are combined with the license, and multiple services are being performed such that a common output measure to determine a pattern of performance cannot be discerned, the Company recognizes amounts received on a straight line basis over the performance period. Such amounts are recorded as collaboration revenue. Any subsequent reimbursement payments, which are contingent upon the Company’s future research and development expenditures, will be recorded as collaboration revenue and will be recognized on a straight-line basis over the performance period using the cumulative catch up method. The costs associated with these activities are reflected as a component of research and development expense in the statements of operations in the period incurred. In the event of an early termination of a collaboration agreement, any deferred revenue is recognized in the period in which all obligations of the Company under the agreement have been fulfilled. Milestone payments under collaborative arrangements are triggered either by the results of the Company’s research and development efforts, achievement of regulatory goals or by specified sales results by a third-party collaborator. Milestones related to the Company’s development-based activities may include initiation of various phases of clinical trials and applications and acceptance for product approvals by regulatory agencies. Due to the uncertainty involved in meeting these development-based milestones, the determination is made at the inception of the collaboration agreement whether the development-based milestones are considered to be substantive (i.e. not just achieved through passage of time). In addition, the amounts of the payments assigned thereto are considered to be commensurate with the enhancement of the value of the delivered intellectual property as a result of the Company’s performance. Because the Company’s involvement is necessary to the achievement of development-based milestones, the Company would account for development-based milestones as revenue upon achievement of the substantive milestone events. Milestones related to sales-based activities may be triggered upon events such as first commercial sale of a product or when sales first achieve a defined level. Since these sales-based milestones would be achieved after the completion of the Company’s development activities, the Company would account for the sales-based milestones in the same manner as royalties, with revenue recognized upon achievement of the milestone. Royalties based on reported sales of licensed products will be recognized based on contract terms when reported sales are reliably measurable and collectability is reasonably assured. To date, none of the Company’s products have been approved and therefore the Company has not earned any royalty revenue from product sales. In territories where the Company and a collaborator may share profit, the revenue would be recorded in the period earned. The Company often is required to make estimates regarding drug development and commercialization timelines for compounds being developed pursuant to a collaboration agreement. Because the drug development process is lengthy and the Company’s collaboration agreements typically cover activities over several years, this approach often results in the deferral of significant amounts of revenue into future periods. In addition, because of the many risks and uncertainties associated with the development of drug candidates, the Company’s estimates regarding the period of performance may change in the future. Any change in the Company’s estimates or a termination of the arrangement could result in substantial changes to the period over which the revenues are recognized. Research and Development Expenses Research and development expenses represent costs associated with the ongoing development of novel therapeutics and companion imaging agents for personalized targeted therapies and include salaries and employee benefits, supplies, facility costs related to research activities, and expenses for clinical trials. The Company records accruals for clinical trial expenses based on the estimated amount of work completed. The Company monitors patient enrollment levels and related activities to the extent possible through internal reviews, correspondence, and discussions with research organizations. In the event that a clinical trial is terminated early, the Company records, in the period of termination, an accrual for the estimated remaining costs to complete and close out the trial pursuant to ASC Topic 420, Exit or Disposal Cost Obligations , as a terminated trial does not provide any future economic benefit to the Company. See Note 10 – Restructuring Costs of the Notes to Condensed Financial Statements contained herein for costs incurred during the three and nine months ended September 30, 2017 related to the Company’s restructuring activities in June 2017. Upfront payments made in connection with business collaborations and research and development arrangements are evaluated under ASC Subtopic 730-20, Research and Development Arrangements . Amounts related to future research and development are capitalized as prepaid research and development and are expensed over the service period based upon the level of services provided. As of September 30, 2017, the Company had approximately $0.2 million of capitalized research and development costs included in prepaid expenses. Acquired In-Process Research and Development Expense The Company has acquired and may continue to acquire the rights to develop and commercialize new drug candidates. In accordance with ASC Subtopic 730-25, Accounting for Research and Development Costs , the up-front payments to acquire a new drug compound, as well as future milestone payments when paid or payable, are immediately expensed as acquired in-process research and development (“IPR&D”) in transactions other than a business combination provided that the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no alternative future use. Upon obtaining regulatory approval for marketing, any related milestone payments may be capitalized and amortized over the life of the asset. Stock-Based Compensation The Company accounts for its stock-based compensation pursuant to ASC Topic 718, Compensation — Stock Compensation (“ASC 718”), which requires the recognition of the fair value of stock-based compensation in net income. Stock-based compensation consists of stock options, which are granted at exercise prices at or above the fair market value of the Company’s common stock on the dates of grant, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), and shares available for purchase under the Company’s 2010 Employee Stock Purchase Plan (“ESPP”). For PRSUs issued by the Company, stock-based compensation expense would be recognized if and when the Company determines that it is probable that the performance conditions will be achieved. For RSUs and stock options issued by the Company, stock-based compensation expense is recognized ratably over the service period. The Company recognizes compensation cost based on the grant-date fair value estimated in accordance with the provisions of ASC 718. Net Loss Per Share Basic net loss per share is calculated by dividing the net 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 loss per share is computed by dividing the net 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 ESPP are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Common stock equivalents As of September 30, 2016 and 2017, the following number of potential common stock equivalents were outstanding: As of September 30, 2016 2017 Outstanding common stock options 6,544,738 6,265,333 Outstanding warrants 34,647 756,647 Outstanding RSUs 414,018 478,087 Shares to be purchased under the ESPP 34,853 18,323 Total 7,028,256 7,518,390 These common stock equivalents were excluded from the determination of diluted net loss per share due to their anti-dilutive effect on earnings. The increase in outstanding warrants is due to warrants issued in connection with the License Agreement. For additional information on the outstanding warrants, see Note 8 – Warrants of the Notes to Condensed Financial Statements contained herein.

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2017
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	3. New Accounting Pronouncements Recently Issued Accounting Standards In January 2017, the FASB issued Accounting Standards Update (“ASU”) 2017-01, Clarifying the Definition of a Business, an update to ASC Topic 805, Business Combinations . This guidance is intended to clarify the definition of a business as it relates to the evaluation of whether a set of transferred assets and activities are accounted for as a business combination or as an asset acquisition. This update was effective for the Company in the three and nine months ended September 30, 2017, as the Company elected early adoption. As a result, the Company considered ASU 2017-01 when evaluating the License Agreement. In the three and nine months ended September 30, 2017, the Company determined that the set of transferred assets and activities included in the License Agreement did not meet the definition of a business and accounted for the License Agreement as an asset acquisition. The adoption of this guidance did not have a material impact on the Company’s financial statements. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , an update to ASC Topic 718, Stock Compensation . This guidance involves improving several aspects of the accounting for share-based payment transactions, including classification of awards as either equity or liabilities, classification on the statement of cash flows, the method of accounting for forfeitures and requiring entities to recognize all income tax effects of awards in the income statement when the awards vest or are settled. This update was effective for the Company for interim and annual reporting periods beginning January 1, 2017. In the nine months ended September 30, 2017, the Company adopted this guidance using the modified retrospective method. As a result, the Company has elected to account for forfeitures as they occur and no longer estimates the number of awards expected to be forfeited. The cumulative effect related to the change in accounting for forfeitures was a $0.3 million increase to the opening balance of retained deficit at January 1, 2017. Additionally, as a result of the adoption, the Company recognized the excess tax benefits of awards that have vested or settled that had previously not been recognized as the related tax deduction had increased the Company’s net operating loss carryforward. The Company determined, consistent with its accounting for existing net operating losses, that a full valuation allowance was required for the excess tax benefits. As such, the Company recognized an increase in its net operating loss carryforward deferred tax asset of $1.7 million and the valuation allowance against the net operating loss carryforward was also increased by $1.7 million, which resulted in no impact to the financial statements. The adoption of this guidance did not have a material impact on the Company’s financial statements. In February 2016, the FASB issued ASU 2016-02, Leases , an update to ASC Topic 842, Leases . This guidance requires lessees to recognize leases as assets and liabilities on their balance sheets but recognize expenses on their income statements in a manner similar to the current accounting guidance. For lessors, the guidance also modifies the classification criteria and the accounting for sales-type and direct finance leases. This update is effective for the Company for interim and annual reporting periods beginning January 1, 2019 unless it elects early adoption. The Company is currently evaluating the impact, if any, the adoption of this guidance will have on its financial statements. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), to clarify the principles used to recognize revenue for all entities. Under ASU 2014-09, an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In order to do so, an entity would follow the five-step process for in-scope transactions: 1) identify the contract with a customer, 2) identify the separate performance obligations in the contract, 3) determine the transaction price, 4) allocate the transaction price to the separate performance obligations in the contract, and 5) recognize revenue when (or as) the entity satisfies a performance obligation. In August 2015, the FASB issued ASU 2015-14, which defers the effective date of ASU 2014-09 by one year. Therefore, ASU 2014-09 will become effective for the Company for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted, but not any earlier than the original effective date of December 15, 2016. An entity can apply the new revenue standard retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. In April 2016, the FASB issued ASU 2016-10, an update to Topic 606, which clarifies how entities should identify performance obligations and evaluate licensing. In May 2016, the FASB issued ASU 2016-12, an update to Topic 606, which clarifies guidance on transition, collectability, noncash consideration and the presentation of sales and other similar taxes. In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which affects narrow aspects of the guidance issued in ASU 2014-09. The Company currently has a limited number of contracts with customers and only one revenue stream, which relates to collaboration and licensing arrangements, and which represents all of the revenue earned in the three and nine months ended September 30, 2017. While the Company has begun the review of its collaboration and licensing arrangements, it is not yet able to estimate the anticipated impact of the adoption of the new standard to its financial statements. The Company will continue to evaluate the impact, if any, the adoption of this guidance will have on its financial statements.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2017
Stockholders' Equity Note [Abstract]
Other Comprehensive Income (Loss)	4. Other Comprehensive Income (Loss) The following tables summarize the accumulated balances related to each component of other comprehensive income (loss) for three months ended September 30, 2016 and 2017: Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at June 30, 2016 $ 96,246 $ 96,246 Unrealized loss (65,901) (65,901) Net amount reclassified to net loss 1,295 1,295 Other comprehensive loss (64,606) (64,606) Balance at September 30, 2016 $ 31,640 $ 31,640 Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at June 30, 2017 $ (34,863) $ (34,863) Unrealized gain 30,303 30,303 Net amount reclassified to net loss — — Other comprehensive income 30,303 30,303 Balance at September 30, 2017 $ (4,560) $ (4,560) The following tables summarize the accumulated balances related to each component of other comprehensive income for the nine months ended September 30, 2016 and 2017: Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at December 31, 2015 $ (79,399) $ (79,399) Unrealized gain 109,744 109,744 Net amount reclassified to net loss 1,295 1,295 Other comprehensive income 111,039 111,039 Balance at September 30, 2016 $ 31,640 $ 31,640 Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at December 31, 2016 $ (41,196) $ (41,196) Unrealized gain 36,636 36,636 Net amount reclassified to net loss — — Other comprehensive income 36,636 36,636 Balance at September 30, 2017 $ (4,560) $ (4,560)

Investments

Investments	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	5. Investments The Company applies the fair value measurement and disclosure provisions of ASC Topic 820, Fair Value Measurements and Disclosures (“ASC 820”). ASC 820, which defines fair value, establishes a framework for measuring fair value in GAAP, and expands disclosures about fair value measurements. Investments consist primarily of investments with original maturities greater than three months, but no longer than 24 months when purchased. ASC 820 establishes a three-level valuation hierarchy for fair value measurements. These valuation techniques are based upon the transparency of inputs (observable and unobservable) to the valuation of an asset or liability as of the measurement date. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions. These two types of inputs create the following fair value hierarchy: Level 1 — Valuation is based on quoted prices for identical assets or liabilities in active markets. Level 2 — Valuation is based on quoted prices for similar assets or liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for the full term of the financial instrument. Level 3 — Valuation is based upon other unobservable inputs that are significant to the fair value measurement. The fair value of the Company’s fixed income securities is based on a market approach using quoted market values. The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2016: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ 6,249,703 $ 6,249,703 $ — $ 6,249,703 Cash equivalents (original maturity of 3 months or less) FDIC insured deposits and money market funds 24,978,489 24,978,489 — 24,978,489 Cash and cash equivalents $ 31,228,192 $ 31,228,192 $ — $ 31,228,192 Short-term investments (due within 1 year) U.S. government treasury obligations $ 86,078,622 $ 86,053,755 $ — $ 86,053,755 Corporate obligations 20,941,799 — 20,925,469 20,925,469 Total short-term investments $ 107,020,420 $ 86,053,755 $ 20,925,469 $ 106,979,224 The following table summarizes the fair value of cash and cash equivalents and investments as of September 30, 2017: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ 6,110,170 $ 6,110,170 $ — $ 6,110,170 Cash equivalents (original maturity of 3 months or less) Repurchase agreements 15,000,000 — 15,000,000 15,000,000 Money market funds 14,573,254 14,573,254 — 14,573,254 U.S. government treasury obligations 9,495,984 9,496,720 — 9,496,720 Corporate obligations 1,998,361 — 1,998,361 1,998,361 Cash and cash equivalents $ 47,177,769 $ 30,180,144 $ 16,998,361 $ 47,178,505 Short-term investments (due within 1 year) U.S. government treasury obligations $ 36,957,883 $ 36,953,105 $ — $ 36,953,105 Corporate obligations 18,949,143 — 18,948,624 18,948,624 Total short-term investments $ 55,907,026 $ 36,953,105 $ 18,948,624 $ 55,901,729 All securities held at December 31, 2016 and September 30, 2017, were classified as available-for-sale as defined by ASC 320. Total unrealized gross gains were $8,257 and $2,623 as of December 31, 2016 and September 30, 2017, respectively. Total unrealized gross losses were $49,453 and $7,18 3 as of December 31, 2016 and September 30, 2017, 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 losses were $53 for the three and nine months ended September 30, 2016. There were no total realized gross gains for the three or nine months ended September 30, 2016. There were no total realized gross gains or total realized gross losses for the three or nine months ended September 30, 2017.

Collaborations

Collaborations	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	6. Collaboration and Other Arrangements ABX Development and License Agreement In September 2017, the Company entered into the License Agreement with ABX that grants the Company exclusive worldwide rights to develop and commercialize PSMA-617 agents. Under the terms of the License Agreement, the Company will be responsible for, and bear the future costs of, worldwide development and commercialization of PSMA-617. As consideration for the exclusive license, the Company made an upfront cash payment on September 29, 2017 of approximately $11.9 million to ABX, consisting of $12.0 million less an immaterial expense reimbursement amount, and issued to ABX 2,000,000 shares of the Company’s common stock (see Note 7 – Stockholders’ Equity (Deficit) of the Notes to Condensed Financial Statements for additional information regarding this issuance) and two warrants to purchase, in the aggregate, 4,000,000 shares of the Company’s common stock (see Note 8 – Warrants of the Notes to Condensed Financial Statements for additional information regarding the warrants). The License Agreement also obligates the Company to pay ABX regulatory milestone payments of up to $25.0 million, sales milestone payments of up to $135.0 million, and tiered royalties, beginning in the mid-teens and not to exceed the mid-twenties, based on percentages of net sales. The Company has accounted for the License Agreement as an asset acquisition and as a result, the upfront payment was expensed in the three months ended September 30, 2017 as acquired IPR&D expense. Any future regulatory milestone payments when paid or payable will be expensed as acquired IPR&D, provided that the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no alternative future use. If the Company obtains regulatory approval for marketing for 177 Lu-PSMA-617 or any other PSMA-617 agents, any related milestone payments may be capitalized as an intangible asset and amortized over the life of the asset. The Company recorded $16.5 million of acquired IPR&D expenses related to the License Agreement for the three months ended September 30, 2017 consisting of the following: · $12.0 million related to the upfront payment to ABX; · $3.8 million related to the fair value of common stock and warrant shares issued; and · $0.7 million of acquisition costs consisting primarily of legal and professional fees. The Company intends to seek regulatory approval to initiate, in the first half of 2018, a phase 3 clinical trial of 177 Lu-PSMA ‑ 617 in patients with mCRPC. In October 2017, the Company entered into an agreement with RadioMedix, Inc., a biotechnology company focused on innovative targeted radiopharmaceuticals for diagnosis, monitoring and therapy of cancer, which enables the transfer of a U.S. Investigational New Drug application of 177 Lu-PSMA-617 from the current sponsor, RadioMedix, to the Company. In addition, under a three-party agreement, entered into in October 2017, among the Company, the University of Sydney (the “University”) and ANZUP, a cooperative cancer trials group operating in Australia and New Zealand pursuing research in genito-urinary malignancies, ANZUP will sponsor and undertake jointly with the University a randomized phase 2 multi-center TheraP trial of 177 Lu-PSMA-617 versus cabazitaxel in 200 mCRPC patients. Under the three-party agreement, the Company will provide the PSMA-617 precursor molecule and financial support for the trial. The Company will have access to data generated from the trial, which is a potentially important supportive trial for future regulatory submissions. The primary financial obligations of the trial, along with labeling PSMA-617 with Lutetium-177, will be the responsibility of the University and ANZUP. 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 any folate receptor-targeted SMDC in Japan. The Company received a $1.0 million non-refundable upfront payment, is eligible for up to $4.5 million based on the successful achievement of regulatory goals for etarfolatide in five different cancer indications and is eligible to receive double-digit percentage royalties on sales of etarfolatide in Japan. For revenue recognition purposes, the Company viewed the agreement with NMP as a multiple element arrangement. Multiple element arrangements are analyzed to determine whether the various performance obligations, or elements, can be separated or whether they must be accounted for as a single unit of accounting. The Company has identified the deliverables related to the collaboration with NMP, which include the license granted to NMP, as well as the obligation to provide pre-clinical and clinical supply of etarfolatide, to provide rights to NMP if a product is developed that replaces etarfolatide, the obligation for the Company to provide clinical data to NMP during the contract period and the coordination of development and commercialization efforts between the Company for any folate receptor-targeted SMDC, 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 folate receptor-targeted SMDC therapeutic drug. The performance period over which the revenue will be recognized continues from the date of execution of the agreement through the end of 2033, the estimated termination date of the contract which is when the Company’s performance obligations will be completed. Any significant changes in the timing of the performance period could result in a change in the revenue recognition period. The Company had deferred revenue related to the agreement of approximately $0.8 million at September 30, 2017. 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 any folate receptor-targeted SMDC 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 the 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 any folate receptor-targeted SMDC therapeutic drug 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.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity (Deficit)	7. Stockholders’ Equity (Deficit) Issuances Related to the License Agreement In connection with the License Agreement, the Company issued to ABX on September 29, 2017, 2,000,000 unregistered shares of the Company’s common stock and two warrants to purchase up to 4,000,000 shares of the Company’s common stock, one of which warrants to purchase 3,278,000 shares was exercised on that same day. Pursuant to a Registration Rights Agreement entered into with ABX, the Company was required to file, within 45 days of September 29, 2017, a registration statement with U.S. Securities and Exchange Commission (the “SEC”) to register the resale of the 6,000,000 shares of common stock issued on September 29, 2017 or issuable pursuant to the warrants issued to ABX, and to use its commercially reasonable efforts to cause the registration statement to be declared effective by the SEC as soon as practicable. On October 12, 2017, the Company filed a Registration Statement on Form S-3, which was declared effective by the SEC on October 24, 2017. 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 11,003,563 and 11,850,563 shares of common stock authorized and reserved under these plans at December 31, 2016 and September 30, 2017, 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 vested 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 vested 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. The Company is using the “simplified” method for “plain vanilla” options to estimate the expected term of the stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option. The risk-free interest rate assumption is derived from the weighted-average yield of a U.S. Treasury security with the same term as the expected life of the options, and the dividend yield assumption is based on historical experience and the Company’s estimate of future dividend yields. The weighted-average value of the individual options granted during the three and nine months ended September 30, 2016 and the nine months ended September 30, 2017 were determined using the following assumptions. There were no options granted during the three months ended September 30, 2017. Three Months Ended September 30, Nine Months Ended September 30, 2016 2017 2016 2017 Expected volatility % — % 92.7 % Risk-free interest rate 1.27 % — 1.47 % 2.15 % Weighted-average expected life (in years) 6.3 — 6.6 Dividend yield % — % % The Company’s stock option activity and related information are summarized as follows: Weighted-Average Remaining Weighted-Average Contractual Term Aggregate Options Exercise Price (In Years) Intrinsic Value (1) Outstanding at January 1, 2017 6,447,594 $ 6.41 Granted during period 653,842 2.17 Exercised during period (7,757) 2.10 Expired during period (163,836) 8.82 Forfeited during period (68,875) 5.59 Outstanding at March 31, 2017 6,860,968 $ 5.96 6.27 $ 282,786 Exercisable at March 31, 2017 5,085,833 $ 6.72 5.33 $ 29,895 Outstanding at April 1, 2017 6,860,968 5.96 Granted during period 198,350 2.27 Exercised during period (44,501) 2.10 Expired during period (123,874) 8.41 Forfeited during period (225,402) 4.15 Outstanding at June 30, 2017 6,665,541 $ 5.89 6.09 $ — Exercisable at June 30, 2017 5,083,084 $ 6.63 5.22 $ — Outstanding at July 1, 2017 6,665,541 5.89 Granted during period — — Exercised during period — — Expired during period (336,625) 7.08 Forfeited during period (63,583) 4.71 Outstanding at September 30, 2017 6,265,333 $ 5.84 5.83 $ — Exercisable at September 30, 2017 4,770,246 6.59 4.94 — (1) The aggregate intrinsic value of the stock options was calculated by identifying those stock options that had a lower exercise price than the closing market price of our common stock on the applicable date and multiplying the difference between the closing market price of our common stock and the exercise price of each of those stock options by the number of shares subject to those stock options that were outstanding or exercisable, as applicable. Since the closing market price of our common stock on June 30, 2017 and September 30, 2017 was lower than the exercise price of all outstanding stock options and exercisable stock options as of those dates, the aggregate intrinsic value of those stock options was zero. As of September 30, 2017, the total remaining unrecognized compensation cost related to stock options granted was $2.6 million, which is expected to be recognized over a weighted average period of approximately 1.5 years. 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. All PRSU awards expired in the second quarter of 2016 when the performance deadline of May 26, 2016 passed. 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 two, three or four equal annual installments beginning on the first anniversary of the date of grant of an RSU. As of September 30, 2017, the Company had 478,087 RSU awards outstanding. As of September 30, 2017, the total remaining unrecognized compensation cost related to RSUs was $1.0 million, which is expected to be recognized over a weighted average period of approximately 1.6 years. The following table sets forth the number of RSUs that were granted, vested and forfeited in the periods indicated: Restricted Weighted-Average Stock Grant Units Date Fair Value Outstanding at January 1, 2017 394,132 $ 4.96 Granted during period 367,985 2.17 Vested during period (128,225) 5.77 Forfeited during period (16,980) 3.50 Outstanding at March 31, 2017 616,912 $ 3.17 Outstanding at April 1, 2017 616,912 $ 3.17 Granted during period 26,400 2.27 Vested during period (23,950) 3.25 Forfeited during period (94,569) 3.06 Outstanding at June 30, 2017 524,793 $ 3.14 Outstanding at July 1, 2017 524,793 $ 3.14 Granted during period — — Vested during period (5,937) 4.85 Forfeited during period (40,769) 3.20 Outstanding at September 30, 2017 478,087 $ 3.11 On October 4, 2017, the Company granted approximately 890,000 RSUs to employees at a weighted-average grant date fair value of $6.10 per RSU. Employee Stock Purchase Plan At January 1, 2017, 825,154 common shares were available for issuance under the ESPP. Shares may be issued under the ESPP twice a year. In the nine months ended September 30, 2017, plan participants purchased 37,236 shares of common stock under the ESPP at an average purchase price of $1.30 per share. There were no purchases in the three months ended September 30, 2017. At September 30, 2017, there were 787,918 common shares available for issuance under the ESPP.

Warrant

Warrant	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Warrant Disclosure [Text Block]	8. Warrants In connection with the License Agreement, the Company issued to ABX on September 29, 2017, two warrants to purchase up to 4,000,000 shares of the Company’s common stock, at a per share exercise price of $1.39, which is equal to the average closing price of the Company’s common stock during the 30 calendar days prior to September 29, 2017. The Company accounted for the warrants at fair value in stockholders’ equity. The warrants contain a conversion feature in the case of certain mergers or consolidations by the Company. Immediately upon issuance, ABX assigned the warrants to an affiliate and certain related parties, which exercised a warrant for 3,278,000 shares on September 29, 2017, resulting in proceeds to the Company in the amount of approximately $4.6 million. The remaining warrant, covering an aggregate of 722,000 shares, remained outstanding as of September 30, 2017, is exercisable until September 29, 2027, and is subject to restrictions on transfer. This warrant was valued using the Black-Scholes model utilizing a ten-year term, the Company’s historic volatility of 91.1%, and an interest rate of 2.28% which is the risk free interest rate of a treasury bond with the same term as the warrants. As of September 30, 2017, there was also outstanding a separate warrant to purchase 34,647 shares of the Company’s common stock, exercisable on or before December 31, 2017 at an exercise price per share of $8.12. This warrant does not contain a conversion feature.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes The Company accounts for income taxes under the liability method in accordance with the provisions of ASC Topic 740, Income Taxes . The Company recognizes future tax benefits, such as net operating losses, to the extent those benefits are expected to be realized in future periods. Due to uncertainty surrounding the realization of its deferred tax assets, the Company has recorded a valuation allowance against its net deferred tax assets. The Company experienced a change in ownership as defined under Section 382 of the U.S. Internal Revenue Code (the “Code”) in August 2011. As a result, the future use of its net operating losses and credit equivalents is currently limited to approximately $218.7 million for 2017. Any available but unused amounts will become available for use in successive years, only if the Company generates future taxable income prior to their expiration, which will begin in 2021. Furthermore, the utilization of the net operating loss carryforwards could be limited beyond the Company's generation of taxable income if an additional 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.

Restructuring Costs

Restructuring Costs	9 Months Ended
	Sep. 30, 2017
Restructuring Costs [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	10. Restructuring Costs In June 2017, the Company refocused its clinical development efforts and aligned its resources to focus on the Company’s highest value opportunities while maintaining key capabilities. The Company’s restructuring activities included a reduction of its workforce by approximately 40%, as well stopping enrollment in its EC1456 phase 1b trial as the assessment of trial data did not yield the level of clinical activity necessary to support continued advancement of EC1456. Pursuant to ASC Topic 420, Exit or Disposal Cost Obligations , the Company recorded $2.3 million of restructuring expenses in the nine months ended September 30, 2017 as follows: · included in research and development expenses were expenses for employee termination benefits of $0.9 million, $0.9 million for the remaining EC1456 phase 1b trial expenses, including site close-out expenses, $0.3 million related to other restructuring expenses, and $0.1 million related to fixed asset impairment charges; and · included in general and administrative expenses were expenses for employee termination benefits of $0.1 million. As of September 30, 2017, the Company had paid all severance related to the restructuring activities, had a clinical trial accrual balance related to the EC1456 phase 1b trial termination of $0.4 million, and an accrual balance related to other restructuring expenses of $37,600, both of which accrual balances are expected to be fully paid by the end of the first quarter of 2018. The following tables summarize the restructuring accruals for the three and nine months ended September 30, 2017. EC1456 Employee Phase 1b Trial Other Termination Termination Restructuring Accrual Accrual Costs Accrual Total Balance, June 30, 2017 $ 181,500 $ 778,100 $ 45,100 $ 1,004,700 Charges for the three months ended September 30, 2017 — — — — Amounts paid in the three months ended September 30, 2017 (181,500) (409,764) (7,500) (598,764) Balance, September 30, 2017 $ — $ 368,336 $ 37,600 $ 405,936 EC1456 Employee Phase 1b Trial Other Termination Termination Restructuring Accrual Accrual Costs Accrual Total Balance, January 1, 2017 $ — $ — $ — $ — Charges for the nine months ended September 30, 2017 1,029,400 947,100 126,500 2,103,000 Amounts paid in the nine months ended September 30, 2017 (1,029,400) (578,764) (88,900) (1,697,064) Balance, September 30, 2017 $ — $ 368,336 $ 37,600 $ 405,936

Significant Accounting Polici17

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed financial statements are prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) for interim financial information to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the accompanying condensed financial statements have been included. Interim results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2017 or any other future period. These condensed financial statements should be read in conjunction with the Company’s audited financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. Subsequent events have been evaluated through the date of issuance, which is the same as the date this Form 10-Q is filed with the Securities and Exchange Commission.
Segment Information	Segment Information Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. All long-lived assets are held in the U.S. The Company views its operations and manages its business in one operating segment.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual amounts may differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers cash and all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents consist primarily of money market instruments, U.S. government treasury obligations, corporate debt securities and repurchase agreements that are maintained by an investment manager.
Investments	Investments Investments consist primarily of investments in U.S. Treasuries and corporate debt securities, which could also include commercial paper, that are maintained by an investment manager. Management determines the appropriate classification of marketable securities at the time of purchase and reevaluates such classification as of each balance sheet date. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities are included in other income. The Company considers and accounts for other-than-temporary impairments according to the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 320, Investments — Debt and Equity Securities (“ASC 320”). The cost of securities sold is based on the specific-identification method. Discounts and premiums on debt securities are amortized to interest income and expensed over the term of the security.
Revenue Recognition	Revenue Recognition The Company recognizes revenues from license and collaboration agreements when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the fee is fixed or determinable, and there is reasonable assurance that the related amounts are collectible in accordance with ASC Topic 605, Revenue Recognition (“ASC 605”). The Company’s license and collaboration agreements may contain multiple elements, including grants of licenses to intellectual property rights, agreement to provide research and development services and other deliverables. The deliverables under such arrangements are evaluated under ASC Subtopic 605-25, Multiple-Element Arrangements (“ASC 605-25”). Under ASC 605-25, each required deliverable is evaluated to determine whether it qualifies as a separate unit of accounting based on whether the deliverable has “stand-alone value” to the customer. The arrangement’s consideration that is fixed or determinable, excluding contingent milestone payments and royalties, is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. In general, the consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. Upfront payments for licensing the Company’s intellectual property are evaluated to determine if the licensee can obtain stand-alone value from the license separate from the value of the research and development services and other deliverables in the arrangement to be provided by the Company. If at the inception of an arrangement the Company determines that the license does not have stand-alone value separate from the research and development services or other deliverables, the license, services and other deliverables are combined as one unit of account and upfront payments are recorded as deferred revenue on the balance sheet and are recognized in a manner consistent with the final deliverable. Subsequent to the inception of an arrangement, the Company evaluates the remaining deliverables for separation as items in the arrangement are delivered. When stand-alone value is identified, the related consideration is recorded as revenue in the period in which the license or other intellectual property rights are delivered. In those circumstances where research and development services or other deliverables are combined with the license, and multiple services are being performed such that a common output measure to determine a pattern of performance cannot be discerned, the Company recognizes amounts received on a straight line basis over the performance period. Such amounts are recorded as collaboration revenue. Any subsequent reimbursement payments, which are contingent upon the Company’s future research and development expenditures, will be recorded as collaboration revenue and will be recognized on a straight-line basis over the performance period using the cumulative catch up method. The costs associated with these activities are reflected as a component of research and development expense in the statements of operations in the period incurred. In the event of an early termination of a collaboration agreement, any deferred revenue is recognized in the period in which all obligations of the Company under the agreement have been fulfilled. Milestone payments under collaborative arrangements are triggered either by the results of the Company’s research and development efforts, achievement of regulatory goals or by specified sales results by a third-party collaborator. Milestones related to the Company’s development-based activities may include initiation of various phases of clinical trials and applications and acceptance for product approvals by regulatory agencies. Due to the uncertainty involved in meeting these development-based milestones, the determination is made at the inception of the collaboration agreement whether the development-based milestones are considered to be substantive (i.e. not just achieved through passage of time). In addition, the amounts of the payments assigned thereto are considered to be commensurate with the enhancement of the value of the delivered intellectual property as a result of the Company’s performance. Because the Company’s involvement is necessary to the achievement of development-based milestones, the Company would account for development-based milestones as revenue upon achievement of the substantive milestone events. Milestones related to sales-based activities may be triggered upon events such as first commercial sale of a product or when sales first achieve a defined level. Since these sales-based milestones would be achieved after the completion of the Company’s development activities, the Company would account for the sales-based milestones in the same manner as royalties, with revenue recognized upon achievement of the milestone. Royalties based on reported sales of licensed products will be recognized based on contract terms when reported sales are reliably measurable and collectability is reasonably assured. To date, none of the Company’s products have been approved and therefore the Company has not earned any royalty revenue from product sales. In territories where the Company and a collaborator may share profit, the revenue would be recorded in the period earned. The Company often is required to make estimates regarding drug development and commercialization timelines for compounds being developed pursuant to a collaboration agreement. Because the drug development process is lengthy and the Company’s collaboration agreements typically cover activities over several years, this approach often results in the deferral of significant amounts of revenue into future periods. In addition, because of the many risks and uncertainties associated with the development of drug candidates, the Company’s estimates regarding the period of performance may change in the future. Any change in the Company’s estimates or a termination of the arrangement could result in substantial changes to the period over which the revenues are recognized.
Research and Development Expenses	Research and Development Expenses Research and development expenses represent costs associated with the ongoing development of novel therapeutics and companion imaging agents for personalized targeted therapies and include salaries and employee benefits, supplies, facility costs related to research activities, and expenses for clinical trials. The Company records accruals for clinical trial expenses based on the estimated amount of work completed. The Company monitors patient enrollment levels and related activities to the extent possible through internal reviews, correspondence, and discussions with research organizations. In the event that a clinical trial is terminated early, the Company records, in the period of termination, an accrual for the estimated remaining costs to complete and close out the trial pursuant to ASC Topic 420, Exit or Disposal Cost Obligations , as a terminated trial does not provide any future economic benefit to the Company. See Note 10 – Restructuring Costs of the Notes to Condensed Financial Statements contained herein for costs incurred during the three and nine months ended September 30, 2017 related to the Company’s restructuring activities in June 2017. Upfront payments made in connection with business collaborations and research and development arrangements are evaluated under ASC Subtopic 730-20, Research and Development Arrangements . Amounts related to future research and development are capitalized as prepaid research and development and are expensed over the service period based upon the level of services provided. As of September 30, 2017, the Company had approximately $0.2 million of capitalized research and development costs included in prepaid expenses.
Acquired In-Process Research and Development Expense	Acquired In-Process Research and Development Expense The Company has acquired and may continue to acquire the rights to develop and commercialize new drug candidates. In accordance with ASC Subtopic 730-25, Accounting for Research and Development Costs , the up-front payments to acquire a new drug compound, as well as future milestone payments when paid or payable, are immediately expensed as acquired in-process research and development (“IPR&D”) in transactions other than a business combination provided that the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no alternative future use. Upon obtaining regulatory approval for marketing, any related milestone payments may be capitalized and amortized over the life of the asset.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for its stock-based compensation pursuant to ASC Topic 718, Compensation — Stock Compensation (“ASC 718”), which requires the recognition of the fair value of stock-based compensation in net income. Stock-based compensation consists of stock options, which are granted at exercise prices at or above the fair market value of the Company’s common stock on the dates of grant, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), and shares available for purchase under the Company’s 2010 Employee Stock Purchase Plan (“ESPP”). For PRSUs issued by the Company, stock-based compensation expense would be recognized if and when the Company determines that it is probable that the performance conditions will be achieved. For RSUs and stock options issued by the Company, stock-based compensation expense is recognized ratably over the service period. The Company recognizes compensation cost based on the grant-date fair value estimated in accordance with the provisions of ASC 718.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net 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 loss per share is computed by dividing the net 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 ESPP are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Common stock equivalents As of September 30, 2016 and 2017, the following number of potential common stock equivalents were outstanding: As of September 30, 2016 2017 Outstanding common stock options 6,544,738 6,265,333 Outstanding warrants 34,647 756,647 Outstanding RSUs 414,018 478,087 Shares to be purchased under the ESPP 34,853 18,323 Total 7,028,256 7,518,390 These common stock equivalents were excluded from the determination of diluted net loss per share due to their anti-dilutive effect on earnings. The increase in outstanding warrants is due to warrants issued in connection with the License Agreement. For additional information on the outstanding warrants, see Note 8 – Warrants of the Notes to Condensed Financial Statements contained herein.

Significant Accounting Polici18

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Schedule of common stock equivalents excluded due to anti-dilutive effect	As of September 30, 2016 2017 Outstanding common stock options 6,544,738 6,265,333 Outstanding warrants 34,647 756,647 Outstanding RSUs 414,018 478,087 Shares to be purchased under the ESPP 34,853 18,323 Total 7,028,256 7,518,390

Other Comprehensive Income (L19

Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2017
Other Comprehensive Income (Loss), Tax [Abstract]
Schedule of components of other comprehensive income	The following tables summarize the accumulated balances related to each component of other comprehensive income (loss) for three months ended September 30, 2016 and 2017: Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at June 30, 2016 $ 96,246 $ 96,246 Unrealized loss (65,901) (65,901) Net amount reclassified to net loss 1,295 1,295 Other comprehensive loss (64,606) (64,606) Balance at September 30, 2016 $ 31,640 $ 31,640 Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at June 30, 2017 $ (34,863) $ (34,863) Unrealized gain 30,303 30,303 Net amount reclassified to net loss — — Other comprehensive income 30,303 30,303 Balance at September 30, 2017 $ (4,560) $ (4,560) The following tables summarize the accumulated balances related to each component of other comprehensive income for the nine months ended September 30, 2016 and 2017: Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at December 31, 2015 $ (79,399) $ (79,399) Unrealized gain 109,744 109,744 Net amount reclassified to net loss 1,295 1,295 Other comprehensive income 111,039 111,039 Balance at September 30, 2016 $ 31,640 $ 31,640 Accumulated Unrealized Net Other Gains (Losses) Comprehensive on Securities Gains (Losses) Balance at December 31, 2016 $ (41,196) $ (41,196) Unrealized gain 36,636 36,636 Net amount reclassified to net loss — — Other comprehensive income 36,636 36,636 Balance at September 30, 2017 $ (4,560) $ (4,560)

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of the fair value of cash and cash equivalents and investments	The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2016: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ 6,249,703 $ 6,249,703 $ — $ 6,249,703 Cash equivalents (original maturity of 3 months or less) FDIC insured deposits and money market funds 24,978,489 24,978,489 — 24,978,489 Cash and cash equivalents $ 31,228,192 $ 31,228,192 $ — $ 31,228,192 Short-term investments (due within 1 year) U.S. government treasury obligations $ 86,078,622 $ 86,053,755 $ — $ 86,053,755 Corporate obligations 20,941,799 — 20,925,469 20,925,469 Total short-term investments $ 107,020,420 $ 86,053,755 $ 20,925,469 $ 106,979,224 The following table summarizes the fair value of cash and cash equivalents and investments as of September 30, 2017: Fair Value Description Cost Level 1 Level 2 (Carrying Value) Cash Cash $ 6,110,170 $ 6,110,170 $ — $ 6,110,170 Cash equivalents (original maturity of 3 months or less) Repurchase agreements 15,000,000 — 15,000,000 15,000,000 Money market funds 14,573,254 14,573,254 — 14,573,254 U.S. government treasury obligations 9,495,984 9,496,720 — 9,496,720 Corporate obligations 1,998,361 — 1,998,361 1,998,361 Cash and cash equivalents $ 47,177,769 $ 30,180,144 $ 16,998,361 $ 47,178,505 Short-term investments (due within 1 year) U.S. government treasury obligations $ 36,957,883 $ 36,953,105 $ — $ 36,953,105 Corporate obligations 18,949,143 — 18,948,624 18,948,624 Total short-term investments $ 55,907,026 $ 36,953,105 $ 18,948,624 $ 55,901,729

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Schedule of weighted-average valuation assumptions	Three Months Ended September 30, Nine Months Ended September 30, 2016 2017 2016 2017 Expected volatility % — % 92.7 % Risk-free interest rate 1.27 % — 1.47 % 2.15 % Weighted-average expected life (in years) 6.3 — 6.6 Dividend yield % — % %
Schedule of stock option activity	Weighted-Average Remaining Weighted-Average Contractual Term Aggregate Options Exercise Price (In Years) Intrinsic Value (1) Outstanding at January 1, 2017 6,447,594 $ 6.41 Granted during period 653,842 2.17 Exercised during period (7,757) 2.10 Expired during period (163,836) 8.82 Forfeited during period (68,875) 5.59 Outstanding at March 31, 2017 6,860,968 $ 5.96 6.27 $ 282,786 Exercisable at March 31, 2017 5,085,833 $ 6.72 5.33 $ 29,895 Outstanding at April 1, 2017 6,860,968 5.96 Granted during period 198,350 2.27 Exercised during period (44,501) 2.10 Expired during period (123,874) 8.41 Forfeited during period (225,402) 4.15 Outstanding at June 30, 2017 6,665,541 $ 5.89 6.09 $ — Exercisable at June 30, 2017 5,083,084 $ 6.63 5.22 $ — Outstanding at July 1, 2017 6,665,541 5.89 Granted during period — — Exercised during period — — Expired during period (336,625) 7.08 Forfeited during period (63,583) 4.71 Outstanding at September 30, 2017 6,265,333 $ 5.84 5.83 $ — Exercisable at September 30, 2017 4,770,246 6.59 4.94 —
Schedule of restricted stock unit activity	Restricted Weighted-Average Stock Grant Units Date Fair Value Outstanding at January 1, 2017 394,132 $ 4.96 Granted during period 367,985 2.17 Vested during period (128,225) 5.77 Forfeited during period (16,980) 3.50 Outstanding at March 31, 2017 616,912 $ 3.17 Outstanding at April 1, 2017 616,912 $ 3.17 Granted during period 26,400 2.27 Vested during period (23,950) 3.25 Forfeited during period (94,569) 3.06 Outstanding at June 30, 2017 524,793 $ 3.14 Outstanding at July 1, 2017 524,793 $ 3.14 Granted during period — — Vested during period (5,937) 4.85 Forfeited during period (40,769) 3.20 Outstanding at September 30, 2017 478,087 $ 3.11

Restructuring Costs (Tables)

Restructuring Costs (Tables)	9 Months Ended
	Sep. 30, 2017
Restructuring Costs [Abstract]
Schedule of restructuring and related costs	The following tables summarize the restructuring accruals for the three and nine months ended September 30, 2017. EC1456 Employee Phase 1b Trial Other Termination Termination Restructuring Accrual Accrual Costs Accrual Total Balance, June 30, 2017 $ 181,500 $ 778,100 $ 45,100 $ 1,004,700 Charges for the three months ended September 30, 2017 — — — — Amounts paid in the three months ended September 30, 2017 (181,500) (409,764) (7,500) (598,764) Balance, September 30, 2017 $ — $ 368,336 $ 37,600 $ 405,936 EC1456 Employee Phase 1b Trial Other Termination Termination Restructuring Accrual Accrual Costs Accrual Total Balance, January 1, 2017 $ — $ — $ — $ — Charges for the nine months ended September 30, 2017 1,029,400 947,100 126,500 2,103,000 Amounts paid in the nine months ended September 30, 2017 (1,029,400) (578,764) (88,900) (1,697,064) Balance, September 30, 2017 $ — $ 368,336 $ 37,600 $ 405,936

Nature of Business and Organi23

Nature of Business and Organization (Details)	1 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reduction in workforce (as a percent)	40.00%

Significant Accounting Polici24

Significant Accounting Policies (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)segmentproduct
Segment Information
Number of Operating Segments | segment	1
Revenue Recognition
Number of products approved for sale | product	0
Prepaid Expenses
Research and Development Expense
Capitalized research and development costs | $	$ 0.2

Significant Accounting Polici25

Significant Accounting Policies - Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Common stock equivalents
Antidilutive securities excluded from computation of earnings per share	7,518,390	7,028,256
Outstanding common stock options
Common stock equivalents
Antidilutive securities excluded from computation of earnings per share	6,265,333	6,544,738
Outstanding warrants
Common stock equivalents
Antidilutive securities excluded from computation of earnings per share	756,647	34,647
RSUs
Common stock equivalents
Antidilutive securities excluded from computation of earnings per share	478,087	414,018
Employee Stock Purchase Plan
Common stock equivalents
Antidilutive securities excluded from computation of earnings per share	18,323	34,853

New Accounting Pronouncements (

New Accounting Pronouncements (Details) - ASU 2016-09 $ in Millions	Jan. 01, 2017USD ($)
New Accounting Pronouncement or Change in Accounting Principle, Retrospective Adjustments [Abstract]
Deferred tax asset, net operating loss	$ 1.7
Valuation allowance for net operating loss deferred tax assets	1.7
Impact of the adoption of ASU 2016-09 on the financial statements	0
New Accounting Pronouncement Early Adoption Effect
New Accounting Pronouncement or Change in Accounting Principle, Retrospective Adjustments [Abstract]
Cumulative effective of the adoption of ASU 2016-09	$ (0.3)

Other Comprehensive Income (L27

Other Comprehensive Income (Loss) - components (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period			$ 137,147,363
Balance at end of period	$ 101,753,466		101,753,466
Unrealized Net Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(34,863)	$ 96,246	(41,196)	$ (79,399)
Unrealized gain (loss)	30,303	(65,901)	36,636	109,744
Net amount reclassified to net loss		1,295		1,295
Other comprehensive income (loss)	30,303	(64,606)	36,636	111,039
Balance at end of period	(4,560)	31,640	(4,560)	31,640
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(34,863)	96,246	(41,196)	(79,399)
Unrealized gain (loss)	30,303	(65,901)	36,636	109,744
Net amount reclassified to net loss		1,295		1,295
Other comprehensive income (loss)	30,303	(64,606)	36,636	111,039
Balance at end of period	$ (4,560)	$ 31,640	$ (4,560)	$ 31,640

Investments (Details)

Investments (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Cash
Cash	$ 6,110,170	$ 6,249,703
Cash equivalents
Cash and cash equivalents at carrying value	47,178,505	31,228,192	$ 34,732,782	$ 15,431,622
Short-term Investments
Short-term investments (due within 1 year)
Available-for-sale Securities	55,901,729	106,979,224
Available-for-sale Securities, Amortized Cost Basis	55,907,026	107,020,420
Short-term Investments | U.S. government treasury obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	36,953,105	86,053,755
Available-for-sale Securities, Amortized Cost Basis	36,957,883	86,078,622
Short-term Investments | Corporate obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	18,948,624	20,925,469
Available-for-sale Securities, Amortized Cost Basis	18,949,143	20,941,799
Cash Equivalents [Member]
Cash equivalents
Cash and cash equivalents at cost	47,177,769	31,228,192
Cash and cash equivalents at carrying value	47,178,505	31,228,192
FDIC insured deposits and money market funds
Cash equivalents
Cash equivalents at cost		24,978,489
Cash Equivalents, at Carrying Value		24,978,489
Repurchase Agreements [Member] | FDIC insured deposits and money market funds
Cash equivalents
Cash equivalents at cost	15,000,000
Cash Equivalents, at Carrying Value	15,000,000
Money Market Funds [Member]
Cash equivalents
Cash equivalents at cost	14,573,254
Cash Equivalents, at Carrying Value	14,573,254
U.S. government treasury obligations
Cash equivalents
Cash equivalents at cost	9,495,984
Cash Equivalents, at Carrying Value	9,496,720
Corporate obligations
Cash equivalents
Cash equivalents at cost	1,998,361
Cash Equivalents, at Carrying Value	1,998,361
Level 1
Cash
Cash	6,110,170	6,249,703
Level 1 | Short-term Investments
Short-term investments (due within 1 year)
Available-for-sale Securities	36,953,105	86,053,755
Level 1 | Short-term Investments | U.S. government treasury obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	36,953,105	86,053,755
Level 1 | Cash Equivalents [Member]
Cash equivalents
Cash and cash equivalents at carrying value	30,180,144	31,228,192
Level 1 | FDIC insured deposits and money market funds
Cash equivalents
Cash Equivalents, at Carrying Value		24,978,489
Level 1 | Money Market Funds [Member]
Cash equivalents
Cash Equivalents, at Carrying Value	14,573,254
Level 1 | U.S. government treasury obligations
Cash equivalents
Cash Equivalents, at Carrying Value	9,496,720
Level 2 | Short-term Investments
Short-term investments (due within 1 year)
Available-for-sale Securities	18,948,624	20,925,469
Level 2 | Short-term Investments | Corporate obligations
Short-term investments (due within 1 year)
Available-for-sale Securities	18,948,624	$ 20,925,469
Level 2 | Cash Equivalents [Member]
Cash equivalents
Cash and cash equivalents at carrying value	16,998,361
Level 2 | Repurchase Agreements [Member] | FDIC insured deposits and money market funds
Cash equivalents
Cash Equivalents, at Carrying Value	15,000,000
Level 2 | Corporate obligations
Cash equivalents
Cash Equivalents, at Carrying Value	$ 1,998,361

Investments unrealized gains (D

Investments unrealized gains (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Unrealized Gain on Securities	$ 2,623		$ 2,623		$ 8,257
Unrealized Loss on Securities	7,183		7,183		$ 49,453
Realized Gain on Securities	$ 0	$ 0	$ 0	$ 0
Realized Loss on Securities		$ 53		$ 53

Collaborations (Details)

Collaborations (Details)	Sep. 29, 2017USD ($)itemshares	Oct. 31, 2017item	Aug. 31, 2013USD ($)item	Sep. 30, 2017USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2017USD ($)
ABX Development and License Agreement
Research And Development In Process Acquired Expense				$ 16,493,132	$ 16,493,132
ABX | License Agreement
ABX Development and License Agreement
Upfront cash payment	$ 11,900,000
Total consideration excluding common stock shares and warrants	$ 12,000,000
Stock Issued During Period Shares Asset Acquisition | shares	2,000,000
Number of warrants issued per agreement | item	2
Aggregate number of common stock shares that may be purchased by exercise of warrants | shares	4,000,000
Research And Development In Process Acquired Expense					16,500,000
Portion of acquired IPRD expense related to the upfront fee paid					12,000,000
Portion of acquired IPRD expense related to the fair value of the common stock and warrants issued					3,800,000
Portion of acquired IPRD expense related to legal and professional fees					700,000
ABX | Achievement Of Regulatory Milestones | License Agreement
ABX Development and License Agreement
Potential milestone payments to be paid				25,000,000	25,000,000	$ 25,000,000
ABX | Achievement Of Sales Milestones | License Agreement
ABX Development and License Agreement
Potential milestone payments to be paid				135,000,000	135,000,000	135,000,000
ABX | Forecast
ABX Development and License Agreement
Number of mCRPC patients included in phase 2 multi-center trial | item		200
NMP | License And Commercialization Agreement
NMP License and Commercialization Agreement
Deferred Revenue				$ 800,000	$ 800,000	800,000
Milestone revenue recognized						$ 0
Period of time for termination notice to be given prior to the first commercial sale in Japan			90 days
Period of time for termination notice to be given after the first commercial sale in Japan			6 months
Period of time for termination notice to be given after Company receives regulatory approval in Japan but fails to launch the product			6 months
NMP | Up-front Payment Arrangement | License And Commercialization Agreement
NMP License and Commercialization Agreement
Upfront payment received			$ 1,000,000
NMP | Achievement Of Regulatory Milestones | License And Commercialization Agreement
NMP License and Commercialization Agreement
Number of cancer indications requiring achievement of regulatory goals | item			5
NMP | Achievement Of Regulatory Milestones | Maximum | License And Commercialization Agreement
NMP License and Commercialization Agreement
Potential milestone payment			$ 4,500,000

Stockholders' Equity - Issuance

Stockholders' Equity - Issuances Related to the License Agreement (Details) - License Agreement - ABX	Sep. 29, 2017itemshares
Issuances Related to the License Agreement
Common stock issued per agreement	2,000,000
Number Of Warrants Issued Per Agreement | item	2
Stock Issued During Period Shares Warrant Exercise	3,278,000
Number of warrants exercised | item	1
Aggregate number of common stock shares that may be purchased by exercise of warrants	4,000,000
Number of shares of common stock filed on registration statement per Registration Rights Agreement	6,000,000
Period of time after license agreement settled the registration statement was required to be filed	45 days

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Options assumptions (Details) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Stock-Based Compensation Plans
Shares authorized and reserved		11,850,563		11,003,563
Fair Value Assumptions
Expected volatility	95.90%	92.70%	99.00%
Risk-free interest rate	1.27%	2.15%	1.47%
Weighted-average expected life (in years)	6 years 3 months 18 days	6 years 10 months 24 days	6 years 7 months 6 days
Dividend yield	0.00%	0.00%	0.00%
1997 And 2007 Plans | Service based vesting
Additional disclosures
Vesting period		4 years
1997 And 2007 Plans | Service based vesting, first period
Additional disclosures
Vesting period		2 years
Shares that will vest (as a percentage)		50.00%
1997 And 2007 Plans | Performance based vesting
Additional disclosures
Vesting period		4 years
2010 Equity Incentive Plan | Minimum
Additional disclosures
Vesting period		3 years
2010 Equity Incentive Plan | Maximum
Additional disclosures
Vesting period		4 years

Stockholders' Equity - Stock 33

Stockholders' Equity - Stock Option Activity (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2017
Equity [Abstract]
Unrecognized compensation cost, net of forfeitures	$ 2,600,000			$ 2,600,000
Weighted average period to recognize stock compensation expense				1 year 6 months
Options
Outstanding, Beginning Balance	6,665,541	6,860,968	6,447,594	6,447,594
Granted during period	0	198,350	653,842
Exercised during period	0	(44,501)	(7,757)
Expired during period	(336,625)	(123,874)	(163,836)
Forfeited during period	(63,583)	(225,402)	(68,875)
Outstanding, Ending Balance	6,265,333	6,665,541	6,860,968	6,265,333
Weighted-Average Exercise Price
Outstanding, Beginning Balance	$ 5.89	$ 5.96	$ 6.41	$ 6.41
Granted during period	0	2.27	2.17
Exercised during period	0	2.10	2.10
Expired during period	7.08	8.41	8.82
Forfeited during period	4.71	4.15	5.59
Outstanding, Ending Balance	$ 5.84	$ 5.89	$ 5.96	$ 5.84
Additional disclosures
Options, Exercisable	4,770,246	5,083,084	5,085,833	4,770,246
Weighted Average Exercise Price, Exercisable	$ 6.59	$ 6.63	$ 6.72	$ 6.59
Weighted Average Remaining Contractual Term	5 years 9 months 29 days	6 years 1 month 2 days	6 years 3 months 7 days
Weighted Average Remaining Contractual Term exercisable at end of period	4 years 11 months 9 days	5 years 2 months 19 days	5 years 3 months 29 days
Aggregate Intrinsic Value	$ 0		$ 282,786	$ 0
Aggregate Intrinsic Value, exercisable at end of period	$ 0		$ 29,895	$ 0

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 04, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2017
Restricted Stock Units
Weighted average period to recognize stock compensation expense					1 year 6 months
RSUs
Restricted Stock Units
Number of shares of common stock to be paid upon vesting of RSU					1
Unrecognized compensation cost		$ 1			$ 1
Weighted average period to recognize stock compensation expense					1 year 7 months 6 days
Restricted Stock Units
Outstanding at beginning of period		524,793	616,912	394,132	394,132
Granted during period		0	26,400	367,985
Vested during period		(5,937)	(23,950)	(128,225)
Forfeited during period		(40,769)	(94,569)	(16,980)
Outstanding at the end of the period		478,087	524,793	616,912	478,087
Weighted-Average Grant Date Fair Value
Outstanding beginning of period		$ 3.14	$ 3.17	$ 4.96	$ 4.96
Granted during period		0	2.27	2.17
Vested during period		4.85	3.25	5.77
Forfeited during period		3.20	3.06	3.50
Outstanding end of period		$ 3.11	$ 3.14	$ 3.17	$ 3.11
RSUs | Subsequent Event [Member]
Restricted Stock Units
Granted during period	890,000
Weighted-Average Grant Date Fair Value
Granted during period	$ 6.10
Minimum | 2010 Equity Incentive Plan
Restricted Stock Units
Vesting period					3 years
Minimum | RSUs
Restricted Stock Units
Vesting period					3 years
Maximum | 2010 Equity Incentive Plan
Restricted Stock Units
Vesting period					4 years
Maximum | RSUs
Restricted Stock Units
Vesting period					4 years

Stockholders' Equity - ESPP (De

Stockholders' Equity - ESPP (Details) - Employee Stock Purchase Plan - $ / shares	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Jan. 01, 2017
Employee Stock Purchase Plan (Abstract)
Shares available for issuance under ESPP	787,918	787,918	825,154
Number of shares purchased under ESPP	0	37,236
Average purchase price of shares under ESPP	$ 1.30	$ 1.30

Warrant (Details)

Warrant (Details) - USD ($)	Sep. 29, 2017	Sep. 30, 2017
Class of Warrant or Right [Line Items]
Proceeds from Warrant Exercises		$ 4,556,420
Expected term of warrants		10 years
Historic volatility used to value the warrants		91.10%
Interest rate assumption used to value the warrants		2.28%
Common Stock [Member]
Class of Warrant or Right [Line Items]
Stock Issued During Period Shares Warrant Exercise		3,278,000
Warrant One
Class of Warrant or Right [Line Items]
Stock Issued During Period Shares Warrant Exercise	3,278,000
Proceeds from Warrant Exercises	$ 4,600,000
Warrant Two
Class of Warrant or Right [Line Items]
Number of shares into which the remaining warrant could be converted		722,000
Warrant Three
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		34,647
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 8.12
ABX
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 1.39

Income Taxes - NOLs (Details)

Income Taxes - NOLs (Details) $ in Millions	Sep. 30, 2017USD ($)
Income Tax Disclosure [Abstract]
Maximum net operating losses and credit equivalents available for use in 2017	$ 218.7

Restructuring Costs (Details)

Restructuring Costs (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended
	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2017
Restructuring Costs
Reduction in workforce (as a percent)	40.00%
Restructuring expense			$ 2,300,000
Accrual balance	$ 1,004,700	$ 1,004,700	405,936
Restructuring Reserve [Roll Forward]
Balance at beginning of period		1,004,700
Charges during the period			2,103,000
Amounts paid during the period		(598,764)	(1,697,064)
Balance at end of period	1,004,700	405,936	405,936
Employee Termination Accrual
Restructuring Costs
Accrual balance	181,500	181,500
Restructuring Reserve [Roll Forward]
Balance at beginning of period		181,500
Charges during the period			1,029,400
Amounts paid during the period		(181,500)	(1,029,400)
Balance at end of period	181,500
EC1456 Phase 1 Trial Termination Accrual
Restructuring Costs
Accrual balance	778,100	778,100	368,336
Restructuring Reserve [Roll Forward]
Balance at beginning of period		778,100
Charges during the period			947,100
Amounts paid during the period		(409,764)	(578,764)
Balance at end of period	778,100	368,336	368,336
Other Restructuring Costs Accrual
Restructuring Costs
Accrual balance	45,100	45,100	37,600
Restructuring Reserve [Roll Forward]
Balance at beginning of period		45,100
Charges during the period			126,500
Amounts paid during the period		(7,500)	(88,900)
Balance at end of period	$ 45,100	$ 37,600	37,600
General and Administrative Expense
Restructuring Costs
Employee termination benefits			100,000
Research and Development Expense.
Restructuring Costs
Employee termination benefits			900,000
Remaining EC1456 phase 1b trial expenses, including site close-out expenses			900,000
Other Restructuring Costs			300,000
Fixed asset impairment			$ 100,000