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Cover - shares	6 Months Ended
Cover - shares	Jun. 30, 2020	Aug. 03, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-36296
Entity Registrant Name	Sesen Bio, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-2025616
Entity Address, Address Line One	245 First Street
Entity Address, Address Line Two	Suite 1800
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	444-8550
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	SESN
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Small Business	true
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		117,171,636
Entity Central Index Key	0001485003
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 37,741	$ 48,121
Prepaid expenses and other current assets	3,727	6,326
Total current assets	41,468	54,447
Restricted cash	20	20
Property and equipment, net of accumulated depreciation of $820 and $758, respectively	185	238
Intangible assets	46,400	46,400
Goodwill	13,064	13,064
Other assets	76	196
Total Assets	101,213	114,365
Current liabilities:
Accounts payable	1,274	1,902
Accrued expenses	4,866	6,169
Other current liabilities	373	446
Total current liabilities	6,513	8,517
Contingent consideration	84,800	120,020
Deferred tax liability	12,528	12,528
Total Liabilities	103,841	141,065
Commitments and contingencies
Stockholders’ Deficit:
Preferred stock, $0.001 par value per share; 5,000,000 shares authorized at June 30, 2020 and December 31, 2019; no shares issued and outstanding at June 30, 2020 and December 31, 2019	0	0
Common stock, $0.001 par value per share; 200,000,000 shares authorized at June 30, 2020 and December 31, 2019; 116,627,653 and 106,801,409 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	116	107
Additional paid-in capital	275,560	266,717
Accumulated deficit	(278,304)	(293,524)
Total Stockholders’ Deficit	(2,628)	(26,700)
Total Liabilities and Stockholders’ Deficit	$ 101,213	$ 114,365

CONDENSED CONSOLIDATED BALANCE SHEETS(Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Property and equipment, accumulated depreciation	$ 820	$ 758
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	116,627,653	106,801,409
Common stock, shares outstanding (in shares)	116,627,653	106,801,409

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (OPERATIONS) AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 4,562	$ 7,944	$ 13,429	$ 12,630
General and administrative	3,318	2,617	6,766	5,672
Change in fair value of contingent consideration	18,480	44,000	(35,220)	43,000
Total operating expenses	26,360	54,561	(15,025)	61,302
Income (Loss) from Operations	(26,360)	(54,561)	15,025	(61,302)
Other income (expense):
Other income, net	16	226	195	487
Net Income (Loss) and Comprehensive Income (Loss)	$ (26,344)	$ (54,335)	$ 15,220	$ (60,815)
Net income (loss) per common share - basic (in dollars per share)	$ (0.24)	$ (0.67)	$ 0.13	$ (0.77)
Weighted-average common shares outstanding - basic (in shares)	112,569	80,739	111,189	79,107
Net income (loss) per common share - diluted (in dollars per share)	$ (0.24)	$ (0.67)	$ 0.11	$ (0.77)
Weighted-average common shares outstanding - diluted (in shares)	112,569	80,739	111,203	79,107

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		77,456,180
Beginning balance (in shares)		77,464,781
Beginning balance at Dec. 31, 2018	$ 44,207	$ 77	$ 230,154	$ (186,024)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(6,480)			(6,480)
Share-based compensation	326		326
Sales of common stock under 2014 ESPP (in shares)		8,601
Sales of common stock under 2014 ESPP	7		7
Ending balance (in shares) at Mar. 31, 2019		77,464,781
Ending balance at Mar. 31, 2019	38,060	$ 77	230,487	(192,504)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		101,265,896
Beginning balance at Dec. 31, 2018	44,207	$ 77	230,154	(186,024)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(60,815)
Ending balance (in shares) at Jun. 30, 2019		101,265,896
Ending balance at Jun. 30, 2019	15,369	$ 101	262,107	(246,839)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		77,464,781
Beginning balance (in shares)		101,265,896
Beginning balance at Mar. 31, 2019	38,060	$ 77	230,487	(192,504)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(54,335)			(54,335)
Share-based compensation	356		356
Exercise of stock options (in shares)		30,000
Exercise of stock options	45		45
Exercise of common stock warrants (in shares)		3,361,115
Exercise of common stock warrants	3,434	$ 4	3,430
Issuance of common stock under ATM offering, net of issuance costs (in shares)		20,410,000
Issuance of common stock under ATM offering, net of issuance costs	27,809	$ 20	27,789
Ending balance (in shares) at Jun. 30, 2019		101,265,896
Ending balance at Jun. 30, 2019	15,369	$ 101	262,107	(246,839)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		101,265,896
Beginning balance (in shares)		106,801,409
Beginning balance (in shares)		109,991,553
Beginning balance at Dec. 31, 2019	(26,700)	$ 107	266,717	(293,524)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	41,564			41,564
Share-based compensation	407		407
Sales of common stock under 2014 ESPP (in shares)		2,785
Sales of common stock under 2014 ESPP	1		1
Issuance of common stock under ATM offering, net of issuance costs (in shares)		3,187,359
Issuance of common stock under ATM offering, net of issuance costs	3,179	$ 3	3,176
Ending balance (in shares) at Mar. 31, 2020		109,991,553
Ending balance at Mar. 31, 2020	18,451	$ 110	270,301	(251,960)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		116,627,653
Beginning balance at Dec. 31, 2019	(26,700)	$ 107	266,717	(293,524)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 15,220
Exercise of stock options (in shares)	0
Exercise of common stock warrants (in shares)	0
Ending balance (in shares) at Jun. 30, 2020		116,627,653
Ending balance at Jun. 30, 2020	$ (2,628)	$ 116	275,560	(278,304)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		109,991,553
Beginning balance (in shares)		116,627,653
Beginning balance at Mar. 31, 2020	18,451	$ 110	270,301	(251,960)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(26,344)			(26,344)
Share-based compensation	491		491
Issuance of common stock under ATM offering, net of issuance costs (in shares)		6,636,100
Issuance of common stock under ATM offering, net of issuance costs	4,774	$ 6	4,768
Ending balance (in shares) at Jun. 30, 2020		116,627,653
Ending balance at Jun. 30, 2020	$ (2,628)	$ 116	$ 275,560	$ (278,304)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		116,627,653

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020
Statement of Stockholders' Equity [Abstract]
Issuance of common stock, issuance costs	$ 0.1	$ 0.1	$ 2.2	$ 0.2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Cash Flows from Operating Activities:
Net income (loss)	$ (26,344)	$ 41,564	$ (54,335)	$ (6,480)	$ 15,220	$ (60,815)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation					61	107
Share-based compensation					898	682
Change in fair value of contingent consideration	18,480		44,000		(35,220)	43,000
Changes in operating assets and liabilities:
Prepaid expenses and other assets					2,719	(1,487)
Accounts payable					(628)	809
Accrued expenses and other liabilities					(1,376)	961
Net Cash Used in Operating Activities					(18,326)	(16,743)	$ (37,500)
Cash Flows from Investing Activities:
Net Cash Used in Investing Activities					(8)	(43)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock under ATM Offering, net of issuance costs					7,953	0
Proceeds from sales of common stock under 2014 ESPP					1	7
Proceeds from exercises of stock options					0	45
Proceeds from the issuance of common stock and common stock warrants, net of issuance costs					0	27,809
Proceeds from the exercise of common stock warrants					0	3,434
Net Cash Provided by Financing Activities					7,954	31,295
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash					(10,380)	14,509
Cash, Cash Equivalents and Restricted Cash - Beginning of Period		$ 48,141		$ 50,442	48,141	50,442	50,442
Cash, Cash Equivalents and Restricted Cash - End of Period	37,761		64,951		37,761	64,951	$ 48,141
Supplemental disclosure of non-cash activities
Right-of-use assets related to the adoption of ASC 842					0	236
Cash paid for amounts included in the measurement of lease liabilities					75	76
Fixed assets included in Accrued Expenses					0	119
Deemed dividend on adjustment of exercise price on certain warrants	$ 147		$ 0		$ 147	$ 0

DESCRIPTION OF BUSINESS	6 Months Ended
DESCRIPTION OF BUSINESS	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	DESCRIPTION OF BUSINESS Sesen Bio, Inc. ("Sesen" or the “Company”), a Delaware corporation formed in February 2008, is a late-stage clinical company developing targeted fusion protein therapeutics ("TFPTs") for the treatment of patients with cancer. The Company’s most advanced product candidate, Vicineum^TM, also known as VB4-845, is a locally-administered targeted fusion protein composed of an anti-epithelial cell adhesion molecule ("EpCAM") antibody fragment tethered to a truncated form of Pseudomonas exotoxin A. The Company has an ongoing single-arm, multi-center, open-label Phase 3 clinical trial of Vicineum as a monotherapy in patients with high-risk, bacillus Calmette-Guérin ("BCG")-unresponsive non-muscle invasive bladder cancer ("NMIBC") (the "VISTA Trial"). The VISTA Trial completed enrollment in April 2018 with a total of 133 patients, and in December 2019, the Company initiated submission of the Biologics License Application ("BLA") for Vicineum to the United States Food and Drug Administration ("FDA") under Rolling Review, which enables individual modules to be submitted and reviewed on an ongoing basis, rather than waiting for all sections to be completed before submission. The Company operates in one segment under the direction of its Chief Executive Officer (chief operating decision maker). Viventia Acquisition In September 2016, the Company entered into a Share Purchase Agreement with Viventia Bio, Inc., a corporation incorporated under the laws of the Province of Ontario, Canada ("Viventia"), the shareholders of Viventia named therein (the “Selling Shareholders”) and, solely in its capacity as seller representative, Clairmark Investments Ltd., a corporation incorporated under the laws of the Province of Ontario, Canada (“Clairmark”) (the “Share Purchase Agreement”), pursuant to which the Company agreed to and simultaneously completed the acquisition of all of the outstanding capital stock of Viventia from the Selling Shareholders (the “Viventia Acquisition”). In connection with the closing of the Viventia Acquisition, the Company issued 4.0 million shares of its common stock to the Selling Shareholders, which at that time represented approximately 19.9% of the voting power of the Company as of immediately prior to the issuance of such shares. Clairmark is an affiliate of Leslie L. Dan, a director of the Company until his retirement in July 2019. In addition, under the Share Purchase Agreement, the Company is obligated to pay to the Selling Shareholders certain post-closing contingent cash payments upon the achievement of specified milestones and based upon net sales, in each case subject to the terms and conditions set forth in the Share Purchase Agreement, including: (i) a one-time milestone payment of $12.5 million payable upon the first sale of Vicineum (the “Purchased Product”), in the United States; (ii) a one-time milestone payment of $7.0 million payable upon the first sale of the Purchased Product in any one of certain specified European countries; (iii) a one-time milestone payment of $3.0 million payable upon the first sale of the Purchased Product in Japan; and (iv) quarterly earn-out payments equal to 2% of net sales of the Purchased Product during specified earn-out periods. Such earn-out payments are payable with respect to net sales in a country beginning on the date of the first sale in such country and ending on the earlier of (i) December 31, 2033 and (ii) fifteen years after the date of such sale, subject to early termination in certain circumstances if a biosimilar product is on the market in the applicable country (collectively, the "Contingent Consideration"). Under the Share Purchase Agreement, the Company, its affiliates, licensees and subcontractors are required to use commercially reasonable efforts, for the first seven years following the closing of the Viventia Acquisition, to achieve marketing authorizations throughout the world and, during the applicable earn-out period, to commercialize the Purchased Product in the United States, France, Germany, Italy, Spain, United Kingdom, Japan, China and Canada. Certain of these payments are payable to individuals or affiliates of individuals that were previously employees or members of the Company's board of directors. Liquidity and Going Concern As of June 30, 2020, the Company had cash and cash equivalents of $37.7 million, net working capital of $35.0 million and an accumulated deficit of $278.3 million. The Company incurred negative cash flows from operating activities of $37.5 million for the year ended December 31, 2019 and $18.3 million for the six months ended June 30, 2020. Since its inception, the Company has received no revenue from sales of its products, and management anticipates that operating losses will continue for the foreseeable future as the Company continues its ongoing Phase 3 VISTA Trial for Vicineum for the treatment of high-risk NMIBC and seeks marketing approval from the FDA. The Company has financed its operations to date primarily through private placements of its common stock, preferred stock, common stock warrants and convertible bridge notes, venture debt borrowings, its initial public offering ("IPO"), follow-on public offerings, sales effected in "at-the-market" ("ATM") offerings, a License Agreement with F. Hoffmann-La Roche Ltd and Hoffman-La Roche Inc. (collectively, "Roche") (the "License Agreement with Roche") and, to a lesser extent, from a collaboration. See “Note 9. Stockholders’ Equity” below for information regarding the Company’s recently completed equity financings. Under Accounting Standards Codification ("ASC") Topic 205-40, Presentation of Financial Statements - Going Concern, management is required at each reporting period to evaluate whether there are conditions and events, considered in the aggregate, that raise substantial doubt about an entity's ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management's plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists, management evaluates whether the mitigating effect of its plans sufficiently alleviates the substantial doubt about the Company's ability to continue as a going concern. The mitigating effect of management's plans, however, is only considered if both (i) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued and (ii) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved by the Company's board of directors before the date that the financial statements are issued. The Company's future success is dependent on its ability to develop and commercialize Vicineum for the treatment of high-risk NMIBC, and ultimately upon its ability to attain profitable operations. In order to commercialize its product candidates, including Vicineum for the treatment of high-risk NMIBC, the Company needs to complete clinical development and comply with comprehensive regulatory requirements. The Company is subject to a number of risks similar to other late-stage clinical companies, including, but not limited to, successful discovery and development of its product candidates, raising additional capital, development and commercialization by its competitors of new technological innovations, protection of proprietary technology and market acceptance of its products. The successful discovery and development of product candidates, including Vicineum for the treatment of high-risk NMIBC, requires substantial working capital, and management expects to seek additional funds through equity or debt financings or through additional collaboration, licensing transactions or other sources. The Company may be unable to obtain equity or debt financings or enter into additional collaboration or licensing transactions at favorable terms, or at all. To the extent that the Company raises additional capital through the sale of equity or convertible debt securities, the ownership interests of existing stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of existing stockholders. Debt financing, if available, may involve agreements that include liens or other restrictive covenants limiting the Company's ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If the Company raises additional funds through government or other third-party funding, strategic collaborations and alliances or licensing arrangements, it may have to relinquish valuable rights to its technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable. If the Company is unable to raise additional funds when needed, it may be required to implement cost reduction strategies and delay, limit, reduce or terminate its product development or future commercialization efforts or grant rights to develop and market products or product candidates that management would otherwise prefer to develop and market. The Company's management does not believe that its cash and cash equivalents of $37.7 million as of June 30, 2020 is sufficient to fund the Company's current operating plan for at least twelve months after the issuance of these condensed consolidated financial statements. Given the history of significant losses, negative cash flows from operations, limited cash resources currently on hand, the ongoing COVID-19 pandemic and dependence by the Company on its ability - about which there can be no certainty - to obtain additional financing to fund its operations after the current cash resources are exhausted, substantial doubt exists about the Company's ability to continue as a going concern. These condensed consolidated financial statements were prepared under the assumption that the Company will continue as a going concern and do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

BASIS OF PRESENTATION	6 Months Ended
BASIS OF PRESENTATION	Jun. 30, 2020
Accounting Policies [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the ASC and Accounting Standards Updates (“ASUs”), promulgated by the Financial Accounting Standards Board (“FASB”). Interim Financial Statements The accompanying unaudited interim condensed consolidated financial statements have been prepared from the books and records of the Company in accordance with GAAP for interim financial information and Rule 10-01 of Regulation S-X promulgated by the United States Securities and Exchange Commission (“SEC”), which permit reduced disclosures for interim periods. All adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the accompanying condensed consolidated balance sheets and statements of income (operations) and comprehensive income (loss), stockholders’ equity and cash flows have been made. Although these interim financial statements do not include all of the information and footnotes required for complete annual financial statements, management believes the disclosures are adequate to make the information presented not misleading. These unaudited interim results of operations and cash flows for the six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the full year. These unaudited interim condensed consolidated financial statements and footnotes should be read in conjunction with the Company’s audited annual consolidated financial statements and footnotes included in its Annual Report on Form 10-K, as filed with the SEC on March 16, 2020, wherein a more complete discussion of significant accounting policies and certain other information can be found. Use of Estimates The preparation of financial statements in accordance with GAAP and the rules and regulations of the SEC requires the use of estimates and assumptions, based on judgments considered reasonable, which affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates and assumptions on historical experience, known trends and events and various other factors that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Although management believes its estimates and assumptions are reasonable when made, they are based upon information available at the time they are made. Management evaluates the estimates and assumptions on an ongoing basis and, if necessary, makes adjustments. Due to the risks and uncertainties involved in the Company’s business and evolving market conditions, and given the subjective element of the estimates and assumptions made, actual results may differ from estimated results. The most significant estimates and judgments impact the fair value of intangible assets, goodwill and contingent consideration; income taxes (including the valuation allowance for deferred tax assets); research and development expenses; and going concern considerations. Principles of Consolidation The Company’s consolidated financial statements include the accounts of the Company, its wholly owned subsidiary Viventia and its indirect subsidiaries, Viventia Bio USA Inc. and Viventia Biotech (EU) Limited. All intercompany transactions and balances have been eliminated in consolidation. Foreign Currency Translation The functional currency of the Company and each of its subsidiaries is the U.S. dollar.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	Jun. 30, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIESThe Company's complete summary of significant accounting policies can be found in "Item 15. Exhibits and Financial Statement Schedules - Note 3. Summary of Significant Accounting Policies" in the audited annual consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2019.

RECENT ACCOUNTING PRONOUNCEMENTS	6 Months Ended
RECENT ACCOUNTING PRONOUNCEMENTS	Jun. 30, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS Adopted in 2020 In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"). ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets held. The amendments in ASU 2016-13 eliminate the probable threshold for initial recognition of a credit loss in current GAAP and reflect an entity’s current estimate of all expected credit losses. ASU 2016-13 is effective for annual and interim periods beginning January 1, 2020 and is to be applied using a modified retrospective transition method. The Company adopted this guidance effective January 1, 2020, and it did not have a material impact on the Company’s financial position, results of operations or cash flows. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurements ("ASU 2018-13"). ASU 2018-13 modifies fair value measurement disclosure requirements. ASU 2018-13 is effective for annual and interim periods beginning after December 15, 2019. The Company adopted this guidance effective January 1, 2020, and although it resulted in some additional footnote disclosures, it did not have a material impact on the Company’s disclosures. For the new disclosures regarding our Level 3 instruments, please read Note 5, Fair Value Measurements and Financial Instruments, to these condensed consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15"). ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance to determine which implementation costs to defer and recognize as an asset. The effective date for ASU 2018-15 is for annual and interim periods beginning after December 15, 2019. The amendments in this ASU should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company adopted this guidance effective January 1, 2020, and it did not have a material impact on the Company’s financial position, results of operations or cash flows. Pending Adoption In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"). ASU 2019-12 simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments in ASU 2019-12 also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted. The method with which the amendments in this ASU are to be applied varies depending on the nature of the tax item impacted by amendment. Because the Company generates losses and pays no income taxes, it does not expect the adoption of ASU 2019-12 to have a material impact on the Company's financial position, results of operations or cash flows.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 65
-Paragraph 1
-Subparagraph (g)(2)
-URI http://asc.fasb.org/extlink&oid=113356391&loc=SL49131195-203048

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-URI http://asc.fasb.org/topic&trid=2122394

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 65
-Paragraph 1
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=113356391&loc=SL49131195-203048

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section S99
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=112272810&loc=SL108384541-122693

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 65
-Paragraph 1
-Subparagraph (i)(2)
-URI http://asc.fasb.org/extlink&oid=113356391&loc=SL49131195-203048

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(iii)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
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+ Details

FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS

The carrying values of cash and cash equivalents, restricted cash, prepaid expenses and other current assets, and accounts payable on the Company’s consolidated balance sheets approximated their fair values as of June 30, 2020 and December 31, 2019 due to their short-term nature.

Certain of the Company’s financial instruments are measured at fair value using a three-level hierarchy that prioritizes the inputs used to measure fair value. This fair value hierarchy prioritizes the use of observable inputs and minimizes the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows:

Level 1: Inputs are quoted prices for identical instruments in active markets.

Level 2: Inputs are quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; or model-derived valuations whose inputs are observable or whose significant value drivers are observable.

Level 3: Inputs are unobservable and reflect the Company’s own assumptions, based on the best information available, including the Company’s own data.

The following tables set forth the carrying amounts and fair values of the Company's financial instruments measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019 (in thousands):


	June 30, 2020
					Fair Value Measurement Based on
	Carrying Amount		Fair Value		Quoted Prices in Active Markets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (cash equivalents)	$	31,339	$	31,339	$	31,339	$	—	$	—
Liabilities:
Contingent consideration	$	84,800	$	84,800	$	—	$	—	$	84,800


	December 31, 2019
					Fair Value Measurement Based on
	Carrying Amount		Fair Value		Quoted Prices in Active Markets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (cash equivalents)	$	31,146	$	31,146	$	31,146	$	—	$	—
Liabilities:
Contingent consideration	$	120,020	$	120,020	$	—	$	—	$	120,020

The Company evaluates transfers between fair value levels at the end of each reporting period. There were no transfers of assets or liabilities between fair value levels during the six months ended June 30, 2020.

Contingent Consideration

On September 20, 2016, the Company acquired Viventia through the issuance of common stock plus contingent consideration, pursuant to the terms of a Share Purchase Agreement. The Company recorded the acquired assets and liabilities based on their estimated fair values as of the acquisition date and finalized its purchase accounting for the Viventia Acquisition during the third quarter of 2017. The contingent consideration relates to amounts potentially payable to the former shareholders of Viventia under the Share Purchase Agreement. Contingent consideration is measured at its estimated fair value at each reporting period, with fluctuations in value resulting in a non-cash charge to earnings (or loss) during the period. The estimated fair value measurement is based on significant inputs, including internally developed financial forecasts, probabilities of success, and the timing of certain milestone events and achievements, which are not observable in the market, representing a Level 3 measurement within the fair value hierarchy. The valuation of contingent consideration requires the use of significant assumptions and judgments, which management believes are consistent with those that would be made by a market participant. Management reviews its assumptions and judgments on an ongoing basis as additional market and other data is obtained, and any future changes in the assumptions and judgments utilized by management may cause the estimated fair value of contingent consideration to fluctuate materially, resulting in earnings volatility.

The following table sets forth a summary of the change in the fair value of the Company's contingent consideration liability, measured on a recurring basis at each reporting period, for the six months ended June 30, 2020 (in thousands):


Balance at December 31, 2019	$	120,020
Change in fair value of contingent consideration	(35,220)
Balance at June 30, 2020	$	84,800

The fair value of the Company’s contingent consideration was determined using probabilities of successful achievement of regulatory milestones and commercial sales, the period in which these milestones and sales are expected to be achieved ranging from 2021 to 2033, and the level of commercial sales of Vicineum forecasted for the United States, Europe, Japan and other potential markets. There have been no changes to the valuation methods utilized during the six months ended June 30, 2020. Because of the business environment uncertainty created by the ongoing COVID-19 pandemic, management carefully reviewed as of June 30, 2020 all of the Company’s financial forecast assumptions related to probability, timing and anticipated level of commercial sales, which were used to determine the estimated fair value of contingent consideration, and updated its forecasts for commercial sales in the second quarter of 2020 to reflect certain changes within the current competitive landscape. However, given the evolving and uncertain nature of the COVID-19 pandemic, management will continue to closely monitor developments in order to timely determine if any financial forecast changes may be required. As of June 30, 2020, no financial forecast changes due to COVID-19 were currently required. Changes to probabilities of success, timing of certain milestones and achievements, and level of commercial sales could materially affect the valuation of contingent consideration.

However, the estimated fair value of contingent consideration is also determined by applying appropriate discount rates to future cash outflows related to the contingent payment obligations, and these discount rates have increased significantly as a result of the extreme volatility of financial markets as global economies shut down in order to contain the spread of COVID-19. The milestone payments constitute debt-like obligations, and the high-yield debt index rate applied to the milestones in order to determine the estimated fair value increased from 11.8% as of December 31, 2019 to 14.5% as of June 30, 2020. The discount rate applied to the 2% royalty due on forecasted Vicineum revenues is derived from the Company’s estimated weighted-average cost of capital (“WACC”), and this WACC-derived discount rate increased from 5.6% as of December 31, 2019 to 13.2% as of June 30, 2020. These significant increases in the applicable discount rates, in conjunction with changes to the competitive

landscape, resulted in a $35.2 million decrease in the estimated fair value of contingent consideration as of June 30, 2020. Changes to the discount rates could materially affect the valuation of the contingent consideration.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

INTANGIBLE ASSETS AND GOODWILL

6 Months Ended

Jun. 30, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSETS AND GOODWILL

Intangible Assets

Intangible assets on the Company's consolidated balance sheet are the result of the Viventia Acquisition in September 2016. The following table sets forth the composition of intangible assets as of June 30, 2020 and December 31, 2019 (in thousands):


	June 30, 2020		December 31, 2019
IPR&D intangible assets:
Vicineum United States rights	$	31,700	$	31,700
Vicineum European Union rights	14,700		14,700
Total Intangibles	$	46,400	$	46,400

Goodwill

Goodwill on the Company's consolidated balance sheet is the result of the Viventia Acquisition in September 2016. Goodwill had a carrying value of $13.1 million as of June 30, 2020 and December 31, 2019.

LEASES	6 Months Ended
LEASES	Jun. 30, 2020
Leases [Abstract]
LEASES	LEASES On January 1, 2019, the Company adopted ASC Topic 842, Leases using the optional transition method. The Company’s lease portfolio includes: 1.An operating lease for its 31,100 square foot facility in Winnipeg, Manitoba which consists of manufacturing, laboratory, warehouse and office space, under a five-year renewable lease through September 2020 with a right to renew the lease for one subsequent five-year term. The minimum monthly rent under this lease is $12,800 per month. In addition to rent expense, the Company expects to incur $12,500 per month in related operating expenses. Operating lease cost under this lease, including the related operating costs, was $72,000 and $148,000 for the three and six months ended June 30, 2020 and $71,000 and $146,000 for the three and six months ended June 30, 2019, respectively; 2.Short-term property leases for modular office space for 1) its current corporate headquarters in Cambridge, MA and 2) office space in Philadelphia, PA. The short-term leases renew every four to nine months and currently extend through March 2021. The minimum monthly rent for these office spaces is currently $21,400 per month, which is subject to change if and as the Company adds or deducts space to or from the leases. The Company recorded $65,000 and $131,000 in rent expense for the three and six months ended June 30, 2020 and $53,000 and $129,000 for the three and six months ended June 30, 2019, respectively, for these leases. The asset component of the Company’s operating leases is recorded as operating lease right-of-use assets and reported within other assets on the Company's consolidated balance sheet. The short-term liability is recorded in other current liabilities on the Company’s consolidated balance sheet. Operating lease cost is recognized on a straight-line basis over the lease term.

ACCRUED EXPENSES

6 Months Ended

Jun. 30, 2020

Payables and Accruals [Abstract]

ACCRUED EXPENSES

The following table sets forth the composition of accrued expenses as of June 30, 2020 and December 31, 2019 (in thousands):


	June 30, 2020		December 31, 2019
Research and development	$	3,100	$	3,688
Payroll-related expenses	985		1,638
Severance to former Executives and other employees	66		378
Professional fees	692		378
Other	23		87
Total Accrued Expenses	$	4,866	$	6,169

Management Changes

On August 26, 2019, Richard Fitzgerald departed as the Company's Chief Financial Officer. In connection with his separation from the Company, Mr. Fitzgerald and the Company entered into a Separation Agreement and General Release dated as of September 9, 2019, pursuant to which the Company provided Mr. Fitzgerald with twelve months of separation payments and benefits. The Company recorded $0.3 million of expense, which will be paid through the normal payroll cycle through August 2020.

On August 2, 2019, Dennis Kim, M.D., MPH departed as the Company's Chief Medical Officer. In connection with his separation from the Company, Dr. Kim and the Company entered into a Separation Agreement and General Release dated as of August 2, 2019 (the “Kim Separation Agreement”), pursuant to which the Company provided Dr. Kim with six months of separation payments in the amount of $0.2 million. In addition, Dr. Kim and the Company entered into a Consulting Agreement dated as of August 3, 2019 (the "Kim Consulting Agreement"), pursuant to which the Company agreed to pay Dr. Kim $0.1 million in consulting fees and transition expenses over the following three months ended November 2, 2019. The Company recorded $0.3 million of expenses related to these agreements in 2019. The Kim Consulting Agreement payments were made in a lump sum when the agreement concluded in November 2019. The separation payments were paid through the normal payroll cycle through January 2020, when the Company concluded its obligations under the Kim Separation Agreement.

STOCKHOLDERS' EQUITY (DEFICIT)

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

STOCKHOLDERS' EQUITY (DEFICIT)

Equity Financings

ATM Offering

In November 2019, the Company entered into an Open Market Sale Agreement ^SM (the "Sales Agreement") with Jefferies LLC ("Jefferies"), under which the Company may issue and sell shares of its common stock from time to time for an aggregate sales price of up to $35.0 million through Jefferies (the "ATM Offering"). Sales of common stock under the Sales Agreement are made by any method that is deemed to be an ATM offering as defined in Rule 415(a)(4) of the Securities Act of 1933, as amended, including but not limited to sales made directly on or through the Nasdaq Global Market or any other existing trading market for the common stock. The Company has no obligation to sell any of its common stock and may at any time suspend offers under the Sales Agreement or terminate the Sales Agreement. Subject to the terms and conditions of the Sales Agreement, Jefferies will use its commercially reasonable efforts to sell common stock from time to time, as the sales agent, based upon the Company’s instructions, which include a prohibition on sales below a minimum price set by the Company from time to time. The Company has provided Jefferies with customary indemnification rights, and Jefferies is entitled to a commission at a fixed rate equal to 3.0% of the gross proceeds for each sale of common stock. The Company incurred $0.2 million in legal, accounting and printing costs related to the commencement of the ATM Offering. For the six months ended June 30, 2020, the Company raised $8.0 million of net proceeds from the sale of 9.8 million shares of common stock at a weighted-average price of $0.75 per share under the ATM Offering, including $4.8 million of net proceeds from the sale of 6.6 million shares of common stock at a weighted-average price of $0.69 per share during the three months ended June 30, 2020. Share issue costs, including sales agent commissions, related to the ATM Offering totaled $0.1 million and $0.2 million during the three and six months ended June 30, 2020, respectively.

June 2019 Financing

In June 2019, the Company raised $27.8 million of net proceeds from the sale of 20.4 million shares of common stock and accompanying warrants to purchase an additional 20.4 million shares of common stock in an underwritten public offering (the "June 2019 Financing"). The combined purchase price for each share of common stock and accompanying warrant was $1.47. Subject to certain ownership limitations, the warrants issued in the June 2019 Financing were exercisable immediately upon issuance at an exercise price of $1.47 per share, subject to adjustments as provided under the terms of such warrants, and had a one-year term expiring on June 21, 2020. As of June 30, 2020, all warrants issued in connection with the June 2019 financing have expired.

Preferred Stock

Pursuant to its Amended and Restated Certificate of Incorporation (the "Certificate of Incorporation"), the Company is authorized to issue 5.0 million shares of "blank check" preferred stock, $0.001 par value per share, which enables its board of directors, from time to time, to create one or more series of preferred stock. Each series of preferred stock issued shall have the rights, preferences, privileges and restrictions as designated by the board of directors. The issuance of any series of preferred stock could affect, among other things, the dividend, voting and liquidation rights of the Company's common stock. The Company had no preferred stock issued and outstanding as of June 30, 2020 and December 31, 2019.

Common Stock

Pursuant to its Certificate of Incorporation, the Company is authorized to issue 200.0 million shares of common stock, $0.001 par value per share, of which 116.6 million and 106.8 million shares were issued and outstanding as of June 30, 2020 and December 31, 2019, respectively. In addition, the Company had reserved for issuance the following amounts of shares of its common stock for the purposes described below as of June 30, 2020 and December 31, 2019 (in thousands):


	June 30, 2020	December 31, 2019
Shares of common stock issued	116,628	106,801
Shares of common stock reserved for issuance for:
Warrants	2,485	22,895
Stock options	9,990	6,236
Shares available for grant under 2014 Stock Incentive Plan	5,084	8,753
Shares available for sale under 2014 Employee Stock Purchase Plan	25	28
Total shares of common stock issued and reserved for issuance	134,212	144,713

The voting, dividend and liquidation rights of holders of shares of common stock are subject to and qualified by the rights, powers and preferences of holders of shares of preferred stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company's stockholders; provided, however, that, except as otherwise required by law, holders of common stock shall not be entitled to vote on any amendment to the Company’s Certificate of Incorporation that relates solely to the terms of one or more outstanding series of preferred stock if the holders of such affected series are entitled, either separately or together as a class with the holders of one or more such series, to vote thereon. There shall be no cumulative voting.

Dividends may be declared and paid on the common stock from funds lawfully available thereof as and when determined by the board of directors and subject to any preferential dividend or other rights of any then-outstanding preferred stock. The Company has never declared or paid, and for the foreseeable future does not expect to declare or pay, dividends on its common stock.

Upon the dissolution or liquidation of the Company, whether voluntary or involuntary, holders of common stock will be entitled to receive all assets of the Company available for distribution to its stockholders, subject to any preferential or other rights of any then-outstanding preferred stock.

Warrants

All of the Company’s outstanding warrants are non-tradeable and permanently classified as equity because they meet the derivative scope exception under ASC Topic 815-40, Derivatives and Hedging - Contracts in Entity’s Own Equity ("ASC 815-40"). The following table sets forth the Company's warrant activity for the six months ended June 30, 2020 (in thousands):


			Year-to-Date Warrant Activity
Issued	Exercise Price ⁽¹⁾	Expiration	December 31, 2019	Issued	(Exercised)	(Expired)	June 30, 2020
Jun-2019	$1.47	Jun-2020	20,410	—	—	(20,410)	—
Mar-2018	$0.55*	Mar-2023	1,943	—	—	—	1,943
Nov-2017	$0.55*	Nov-2022	487	—	—	—	487
May-2015	$11.83	Nov-2024	28	—	—	—	28
Nov-2014	$11.04	Nov-2024	27	—	—	—	27
			22,895	—	—	(20,410)	2,485

⁽¹⁾ As of June 30, 2020.

* Exercise price shown subject to further adjustment based on down round provision added by amendment.

In March 2018, the Company raised $9.0 million of net proceeds from the sale of common stock in a registered direct public offering and the sale of warrants to purchase shares of the Company's common stock with an exercise price of $1.20 per share (the "2018 Warrants") in a concurrent private placement. On October 28, 2019, the Company entered into transactions with certain holders of its then outstanding 2018 Warrants to amend their warrants pursuant to a Warrant Amendment Agreement (the "2018 Warrant Amendment Agreements"). The 2018 Warrant Amendment Agreements reduced the exercise price of the warrants from $1.20 to the lesser of (a) $0.95 per share of common stock and (b) the exercise price as determined from time to

time, pursuant to the anti-dilution provisions in the 2018 Warrant Amendment Agreements. During the three months ended June 30, 2020, the anti-dilution provision was triggered; as such, the Company recognized a deemed dividend of approximately $0.1 million which reduced the income available to common stockholders for both the three and six months ended June 30, 2020. As of June 30, 2020, the exercise price of the 2018 Warrants was $0.55. As the Company has an accumulated deficit balance as of June 30, 2020, the deemed dividend was recorded as offsetting debit and credit entries to additional-paid-in capital for the period ended June 30, 2020. As there was no overall impact to additional paid-in capital, the amounts were not presented on the Statement of Stockholders' Equity (Deficit) for the period ended June 30, 2020.

EARNINGS (LOSS) PER SHARE

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

EARNINGS (LOSS) PER SHARE

A net loss cannot be diluted. Therefore, when the Company is in a net loss position, basic and diluted loss per common share are the same. If the Company achieves profitability, the denominator of a diluted earnings per common share calculation includes both the weighted-average number of shares outstanding and the number of common stock equivalents, if the inclusion of such common stock equivalents would be dilutive. Dilutive common stock equivalents potentially include warrants, stock options and non-vested restricted stock awards and units using the treasury stock method, along with the effect, if any, from outstanding convertible securities. The majority of the Company’s outstanding warrants to purchase common stock have participation rights to any dividends that may be declared in the future and are therefore considered to be participating securities. Participating securities have the effect of diluting both basic and diluted earnings per share during periods of income. During periods of loss, no loss is allocated to the participating securities since the holders have no contractual obligation to share in the losses of the Company.

Additionally, an entity that presents earnings per share shall recognize the value of the effect of an anti-dilution provision in an equity-classified freestanding financial instrument in the period the anti-dilution provision is triggered. That effect shall be treated as a deemed dividend and as a reduction of income available to common stockholders in basic earnings per share. The deemed dividend is added back to income available to common stockholders when applying the treasury stock method for diluted earnings per share.

For periods with net income, diluted net earnings per share is calculated by either (i) adjusting the weighted-average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period as determined using the treasury stock method or (ii) the two-class method considering common stock equivalents, whichever is more dilutive. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders.

Accordingly, the Company applied the two-class method to calculate basic and diluted net earnings per share of common stock for the six months ended June 30, 2020. The two-class method was not applied for the three months ended June 30, 2020 and for the three and six months ended June 30, 2019 as the Company’s participating securities do not have any obligation to absorb net losses.

For purposes of the diluted net loss per share calculation, common stock equivalents are excluded from the calculation if their effect would be anti-dilutive.

The following table illustrates the determination of earnings (loss) per share for each period presented:


	Three Months Ended June 30,										Six Months Ended June 30,
	2020		2019				2020				2019
	(in thousands, except per share amounts)
Basic Earnings (Loss) Per Share:
Numerator:
Net income (loss)	$	(26,344)			$	(54,335)			$	15,220			$	(60,815)
Less: Deemed dividend	(147)		—				(147)				—
Less: Income attributable to participating securities - basic	—		—				(322)				—
Net income (loss) attributable to common stockholders - basic	$	(26,491)	$	(54,335)			$	14,751			$	(60,815)

Denominator:
Weighted average common shares outstanding - basic	112,569		80,739				111,189				79,107

Net income (loss) per share applicable to common stockholders - basic	$	(0.24)	$	(0.67)			$	0.13			$	(0.77)


Dilutive Earnings (Loss) Per Share:
Numerator:
Net income (loss)	$	(26,344)	$	(54,335)			$	15,220			$	(60,815)
Less: Deemed Dividend	(147)		—				(147)				—
Less: Income attributable to participating securities - diluted	—		—				(2,473)
Net income (loss) attributable to common stockholders - diluted	$	(26,491)	$	(54,335)			$	12,600			$	(60,815)

Denominator:
Weighted average shares outstanding	112,569		80,739				111,189				79,107

Dilutive impact from:
Stock options and employee stock purchase plan	—		—				14				—
Weighted average common shares outstanding for diluted	112,569		80,739				111,203				79,107

Net income (loss) per share applicable to common stockholders - diluted	$	(0.24)	$	(0.67)			$	0.11			$	(0.77)

The following potentially dilutive securities outstanding as of June 30, 2020 and 2019 have been excluded from the denominator of the diluted income (loss) per share of common stock outstanding calculation as their effect is anti-dilutive (in thousands):


	Three Months Ended June 30,			Six Months Ended June 30,
	2020	2019	2020	2019
Warrants	2,485	5,779	55	5,779
Stock options	9,990	26,307	9,989	26,307
	12,475	32,086	10,044	32,086

SHARE-BASED COMPENSATION

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

SHARE-BASED COMPENSATION

The following table sets forth the amount of share-based compensation expense recognized by the Company by line item on its consolidated statements of income (operations) for the three and six months ended June 30, 2020 and 2019 (in thousands):


	Three Months ended June 30,						Six Months ended June 30,
	2020		2019		2020		2019
Research and development	$	91	$	86	$	171	$	139
General and administrative	400		269		727		543
	$	491	$	355	$	898	$	682

2014 Stock Incentive Plan

The Company's 2014 Stock Incentive Plan, as amended ("2014 Plan"), was adopted by its board of directors in December 2013 and subsequently approved by its stockholders in January 2014. The 2014 Plan became effective immediately prior to the closing of the Company's IPO in February 2014 and provides for the grant of incentive and non-qualified stock options, restricted stock awards and units, stock appreciation rights and other stock-based awards, with amounts and terms of grants determined by the Company's board of directors at the time of grant, to the Company's employees, officers, directors, consultants and advisors. Currently there are only stock options outstanding under the 2014 Plan, which generally vest over a four-year period at the rate of 25% of the grant vesting on the first anniversary of the date of grant and 6.25% of the grant vesting at the end of each successive three-month period thereafter. Stock options granted under the 2014 Plan are exercisable for a period of ten years from the date of grant. There were 7.7 million stock options outstanding under the 2014 Plan as of June 30, 2020. There were 5.1 million shares of common stock available for issuance under the 2014 Plan as of June 30, 2020.

2009 Stock Incentive Plan

The Company maintains a 2009 Stock Incentive Plan, as amended and restated ("2009 Plan"), which provided for the grant of incentive and non-qualified stock options and restricted stock awards and units, with amounts and terms of grants determined by the Company's board of directors at the time of grant, to its employees, officers, directors, consultants and advisors. Upon the closing of its IPO in February 2014, the Company ceased granting awards under the 2009 Plan and all shares (i) available for issuance under the 2009 Plan at such time and (ii) subject to outstanding awards under the 2009 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased without having been fully exercised or resulting in any common stock being issued were carried over to the 2014 Plan. Stock options granted under the 2009 Plan are exercisable for a period of ten years from the date of grant. There were 0.1 million fully vested stock options outstanding under the 2009 Plan as of June 30, 2020.

Out-of-Plan Inducement Grants

From time to time, the Company has granted equity awards to its newly hired executives in accordance with the Nasdaq Stock Market LLC ("Nasdaq") employment inducement grant exemption (Nasdaq Listing Rule 5635(c)(4)). Such grants are made outside of the 2014 Plan and act as an inducement material to the executive's acceptance of employment with the Company. There were 2.2 million stock options outstanding which were granted as employment inducement awards outside of the 2014 Plan as of June 30, 2020.

Stock Options

The following table sets forth a summary of the Company’s total stock option activity, including awards granted under the 2014 Plan and 2009 Plan and inducement grants made outside of stockholder approved plans, for the six months ended June 30, 2020:


	Number of Shares under Option (in thousands)	Weighted-average Exercise Price per Option	Weighted-average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2019	6,236	$1.52	8.8	$	358
Granted	3,754	$0.87
Exercised	—	$0.00
Canceled or forfeited	—	$0.00
Outstanding at June 30, 2020	9,990	$1.27	9.0	$	—
Exercisable at June 30, 2020	2,866	$1.91	8.0	$	—

The Company recognized share-based compensation expense related to stock options of $0.5 million and $0.9 million for the three and six months ended June 30, 2020 and $0.4 million and $0.7 million for the three and six months ended June 30, 2019, respectively. As of June 30, 2020, there was $4.4 million of total unrecognized compensation cost related to non-vested stock options which the Company expects to recognize over a weighted-average period of 2.9 years. The weighted-average grant-date fair value of stock options granted during the six months ended June 30, 2020 was $0.55 per option. The total intrinsic value of stock options exercised during the six months ended June 30, 2020 was de minimus.

For the six months ended June 30, 2020 and 2019, the grant-date fair value of stock options was determined using the following weighted-average inputs and assumptions in the Black-Scholes option pricing model:


	June 30, 2020	June 30, 2019
Fair value of common stock	$0.55	$0.63
Exercise price	$0.87	$0.93
Expected term (in years)	6.02	5.97
Risk-free interest rate	1.4	2.4
Expected volatility	71.3	78.0
Dividend yield	—%	—%

EMPLOYEE BENEFIT PLANS	6 Months Ended
EMPLOYEE BENEFIT PLANS	Jun. 30, 2020
Retirement Benefits [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS 2014 Employee Stock Purchase Plan The Company's 2014 Employee Stock Purchase Plan ("2014 ESPP") was adopted by its board of directors in December 2013 and subsequently approved by its stockholders in January 2014. The 2014 ESPP became effective immediately prior to the closing of the Company's IPO in February 2014 and established an initial reserve of 0.2 million shares of the Company's common stock for issuance to participating employees. The purpose of the 2014 ESPP is to enhance employee interest in the success and progress of the Company by encouraging employee ownership of common stock of the Company. The 2014 ESPP provides employees with the opportunity to purchase shares of the Company’s common stock at a 15% discount to the market price through payroll deductions or lump sum cash investments. The Company estimates the number of shares to be issued at the end of an offering period and recognizes expense over the requisite service period. Shares of the Company's common stock issued and sold pursuant to the 2014 ESPP are shown on the consolidated statements of changes in stockholders' equity (deficit). As of June 30, 2020, there were approximately 25,000 shares of the Company's common stock available for sale under the 2014 ESPP. Defined Contribution Plans United States - 401(k) Plan The Company maintains a 401(k) defined contribution retirement plan which covers all of its U.S. employees. Employees are eligible to participate immediately upon their date of hire. Under the 401(k) plan, participating employees may defer up to 75% of their pre-tax salary, subject to certain statutory limitations. Employee contributions vest immediately. The plan allows for a discretionary match per participating employee up to a maximum $4,000 per year. The expenses incurred for the periods presented were de minimis. Canada - Defined Contribution Plan The Company maintains a defined contribution plan for its Canadian employees. Participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. The Company contributes up to the first 4% of eligible compensation for its Canadian-based employees to the retirement plan. The expenses incurred for the periods presented were de minimis.

LICENSE AGREEMENTS	6 Months Ended
LICENSE AGREEMENTS	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
LICENSE AGREEMENTS	LICENSE AGREEMENTS Vicineum License Agreements License Agreement with Zurich The Company has a License Agreement with the University of Zurich ("Zurich") which grants the Company exclusive license rights, with the right to sublicense, to make, have made, use and sell under certain patents primarily directed to the Company's targeting agent, including an EpCAM chimera and related immunoconjugates and methods of use and manufacture of the same. These patents cover some key aspects of Vicineum. The Company may be obligated to pay $0.75 million in milestone payments for the first product candidate that achieves applicable clinical development milestones. Based on current status, the Company anticipates that these milestones may be triggered by Vicineum's clinical development pathway. As part of the consideration, the Company is also obligated to pay up to a 4% royalty on the net product sales for products covered by or manufactured using a method covered by a valid claim in the Zurich patent rights. Royalties owed to Zurich will be reduced if the total royalty rate owed by the Company to Zurich and any other third party is 10% or greater, provided that the royalty rate to Zurich may not be less than 2% of net sales. The obligation to pay royalties in a particular country expires upon the expiration or termination of the last of the Zurich patent rights that covers the manufacture, use or sale of a product. There is no obligation to pay royalties in a country if there is no valid claim that covers the product or a method of manufacturing the product. License Agreement with Micromet The Company has a License Agreement with Micromet AG ("Micromet"), now part of Amgen, Inc., which grants it nonexclusive rights, with certain sublicense rights, for know-how and patents allowing exploitation of certain single chain antibody products. These patents cover some key aspects of Vicineum. Under the terms of the License Agreement with Micromet, the Company may be obligated to pay up to €3.6 million in milestone payments for the first product candidate that achieves applicable clinical development milestones. Based on current clinical status, the Company anticipates that certain of these milestones may be triggered by Vicineum’s clinical development pathway. The Company is also required to pay up to a 3.5% royalty on the net sales for products covered by the agreement, which includes Vicineum. The royalty rate owed to Micromet in a particular country will be reduced to 1.5% if there are no valid claims covering the product in that country. The obligation to pay royalties in a particular country expires upon the later of the expiration date of the last valid claim covering the product and the tenth anniversary of the first commercial sale of the product in such country. Finally, the Company is required to pay to Micromet an annual license maintenance fee of €50,000, which can be credited towards any royalty payment the Company owes to Micromet. License Agreement with XOMA The Company has a License Agreement with XOMA Ireland Limited ("XOMA") which grants it non-exclusive rights to certain XOMA patent rights and know-how related to certain expression technology, including plasmids, expression strains, plasmid maps and production systems. These patents and related know-how cover some key aspects of Vicineum. Under the terms of the License Agreement with XOMA, the Company is required to pay up to $0.25 million in milestone payments for a product candidate that incorporates know-how under the license and achieves applicable clinical development milestones. Based on current clinical status, the Company anticipates that these milestones may be triggered by Vicineum’s clinical development pathway. The Company is also required to pay a 2.5% royalty on the net sales for products incorporating XOMA’s technology, which includes Vicineum. The Company has the right to reduce the amount of royalties owed to XOMA on a country-by-country basis by the amount of royalties paid to other third parties, provided that the royalty rate to XOMA may not be less than 1.75% of net sales. In addition, the foregoing royalty rates are reduced by 50% with respect to products that are not covered by a valid patent claim in the country of sale. The obligation to pay royalties in a particular country expires upon the later of the expiration date of the last valid claim covering the product and the tenth anniversary of the first commercial sale of the product in such country. Other License Agreements License Agreement with Roche In June 2016, the Company entered into the License Agreement with Roche, pursuant to which the Company granted Roche an exclusive, worldwide license, including the right to sublicense, to its patent rights and know-how related to the Company’s monoclonal antibody EBI-031 and all other IL-6 anti-IL-6 antagonist monoclonal antibody technology owned by the Company (collectively, the "Licensed Intellectual Property"). Under the License Agreement with Roche, Roche is required to continue developing, at its cost, EBI-031 and any other product made from the Licensed Intellectual Property that contains an IL-6 antagonist anti-IL monoclonal antibody (“Licensed Product”) and pursue ongoing patent prosecution, at its cost. Financial Terms The Company received from Roche an upfront license fee of $7.5 million in August 2016 upon the effectiveness of the License Agreement with Roche following approval by the Company's stockholders, and Roche agreed to pay up to an additional $262.5 million upon the achievement of specified regulatory, development and commercialization milestones with respect to up to two unrelated indications. Specifically, an aggregate amount of up to $197.5 million is payable to the Company for the achievement of specified milestones with respect to the first indication, consisting of $72.5 million in development milestones, $50.0 million in regulatory milestones and $75.0 million in commercialization milestones. In September 2016, Roche paid the Company the first development milestone of $22.5 million as a result of the Investigational New Drug application for EBI-031 becoming effective on or before September 15, 2016. Additional amounts of up to $65.0 million are payable upon the achievement of specified development and regulatory milestones in a second indication. In addition, the Company is entitled to receive royalty payments in accordance with a tiered royalty rate scale, with rates ranging from 7.5% to 15% of net sales of potential future products containing EBI-031 and up to 50% of these rates for net sales of potential future products containing other IL-6 compounds, with each of the royalties subject to reduction under certain circumstances and to the buy-out options of Roche. Buy-Out Options The License Agreement with Roche provides for two “option periods” during which Roche may elect to make a one-time payment to the Company and, in turn, terminate its diligence, milestone and royalty payment obligations under the License Agreement with Roche. Specifically, (i) Roche may exercise a buy-out option following the first dosing (“Initiation”) in the first Phase 2 study for a Licensed Product until the day before Initiation of the first Phase 3 study for a Licensed Product, in which case Roche is required to pay the Company $135.0 million within 30 days after Roche's exercise of such buy-out option and receipt of an invoice from the Company, or (ii) Roche may exercise a buy-out option following the day after Initiation of the first Phase 3 study for a Licensed Product until the day before the acceptance for review by the FDA or other regulatory authority of a BLA or similar application for marketing approval for a Licensed Product in either the United States or in the E.U., in which case Roche is required to pay the Company, within 30 days after Roche’s exercise of such buy-out option and receipt of an invoice from the Company, $265.0 million, which amount would be reduced to $220.0 million if none of the Company’s patent rights containing a composition of matter claim covering any compound or Licensed Product has issued in the E.U. Termination Either the Company or Roche may each terminate the License Agreement with Roche if the other party breaches any of its material obligations under the agreement and does not cure such breach within a specified cure period. Roche may terminate the License Agreement with Roche following effectiveness by providing advance written notice to the Company or by providing written notice if the Company is debarred, disqualified, suspended, excluded, or otherwise declared ineligible from certain federal or state agencies or programs. The Company may terminate the License Agreement with Roche if, prior to the first filing of a BLA for a Licensed Product, there is a period of 12 months where Roche is not conducting sufficient development activities with respect to the products made from the Licensed Intellectual Property.

RELATED PARTY TRANSACTIONS	6 Months Ended
RELATED PARTY TRANSACTIONS	Jun. 30, 2020
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS The Company leases its facility in Winnipeg, Manitoba from an affiliate of Leslie L. Dan, a director of the Company until his retirement in July 2019. The Company paid $0.1 million and $0.1 million of rent for the three and six months ended June 30, 2020, respectively, and $0.1 million and $0.1 million of rent for the three and six months ended June 30, 2019, respectively. All payments include related operating expenses. The Company pays fees under an intellectual property license agreement to Protoden Technologies Inc. (“Protoden”), a company owned by Clairmark, an affiliate of Mr. Dan. Pursuant to the agreement, the Company has an exclusive, perpetual, irrevocable and non-royalty bearing license, with the right to sublicense, to certain patents and technology to make, use and sell products that utilize such patents and technology. The annual fee is $0.1 million. Upon expiration of the term on December 31, 2024, the licenses granted to the Company will require no further payments to Protoden. For each of the six months ended June 30, 2020 and 2019, the Company paid $0.1 million under this agreement. The Company did not make payments under this agreement during the three months ended June 30, 2020 and 2019.Mr. Dan was not deemed a related party during the three and six months ended June 30, 2020; as such, only payments made during the three and six months ended June 30, 2019 are considered payments to a related party.

SUBSEQUENT EVENTS	6 Months Ended
SUBSEQUENT EVENTS	Jun. 30, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On July 30, 2020, the Company and its a wholly-owned subsidiary, Viventia Bio, Inc., entered into an exclusive license agreement with Qilu Pharmaceutical Co., Ltd. (“Qilu”) ("Qilu License Agreement") pursuant to which the Company granted Qilu an exclusive, sublicensable, royalty-bearing license, under certain intellectual property owned or exclusively licensed by the Company, to develop, manufacture and commercialize Vicineum™ (the “Licensed Product”) for the treatment of NMIBC and other types of cancer (the “Field”) in China, Hong Kong, Macau and Taiwan (the “Territory”). The Company also granted Qilu a non-exclusive, sublicensable, royalty-bearing sublicense, under certain other intellectual property licensed by the Company to develop, manufacture and commercialize the Licensed Product in the Territory. The Company retains development, manufacturing and commercialization rights with respect to Vicineum in the rest of the world. In partial consideration for the rights granted by the Company, Qilu agreed to pay to the Company (i) a one-time upfront cash payment of $12 million payable within 45 business days of the execution date, subject to delivery by the Company of certain know-how and other documentation related to the Licensed Product to Qilu, and (ii) milestone payments totaling up to $23 million upon the achievement of certain technology transfer, development and regulatory milestones. Qilu also agreed to pay the Company a 12% royalty based upon annual net sales of Licensed Products in the Territory. The royalties are payable on a Licensed Product-by-Licensed Product and region-by-region basis commencing on the first commercial sale of a Licensed Product in a region and continuing until the latest of (i) twelve years after the first commercial sale of such Licensed Product in such region, (ii) the expiration of the last valid patent claim covering or claiming the composition of matter, method of treatment, or method of manufacture of such Licensed Product in such region, and (iii) the expiration of regulatory or data exclusivity for such Licensed Product in such region (collectively, the “Royalty Term”). The royalty rate is subject to reduction under certain circumstances, including when there is no valid claim of a licensed patent that covers a Licensed Product in a particular region or no data or regulatory exclusivity of a Licensed Product in a particular region. Qilu is responsible for all costs related to developing, obtaining regulatory approval of and commercializing the Licensed Products in the Field in the Territory. Qilu is required to use commercially reasonable efforts to develop, seek regulatory approval for, and commercialize at least one Licensed Product in the Field in the Territory. A joint development committee will be established between the Company and Qilu to coordinate and review the development, manufacturing and commercialization plans with respect to the Licensed Products in the Territory. The Company and Qilu also agreed to negotiate in good faith the terms and conditions of a supply agreement and related quality agreement pursuant to which the Company will manufacture or have manufactured and supply Qilu with all quantities of the Licensed Product necessary for Qilu to develop and commercialize the Licensed Product in the Field in the Territory until the Company has completed manufacturing technology transfer to Qilu and approval of a Qilu manufactured product by the National Medical Products Administration in China for the Licensed Product. The Qilu License Agreement will expire on a Licensed Product-by-Licensed Product and region-by-region basis on the date of the expiration of all applicable Royalty Terms. Upon expiration of the Qilu License Agreement, Qilu will have a fully paid-up, freely transferable, perpetual license to use the patent rights and know-how licensed from the Company to research, develop, have developed, manufacture, have manufactured, use, sell, offer for sale, import, export and otherwise commercialize the applicable Licensed Product in the Field in the Territory. Either party may terminate the Qilu License Agreement for the other party’s material breach following a cure period or upon certain insolvency events. If the Qilu License Agreement is terminated by Qilu for the Company’s material breach, the license granted to Qilu will become fully paid-up, royalty-free, and perpetual. Qilu may terminate the Qilu License Agreement at its sole discretion and without any penalty or liability for any reason or no reason upon 90 calendar days’ prior written notice to the Company. Qilu has the right to receive a refund of all amounts paid to the Company in the event the Qilu License Agreement is terminated under certain circumstances. The Qilu License Agreement includes customary representations and warranties, covenants and indemnification obligations for a transaction of this nature.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Jun. 30, 2020
Accounting Policies [Abstract]
Interim Financial Statements	Interim Financial Statements The accompanying unaudited interim condensed consolidated financial statements have been prepared from the books and records of the Company in accordance with GAAP for interim financial information and Rule 10-01 of Regulation S-X promulgated by the United States Securities and Exchange Commission (“SEC”), which permit reduced disclosures for interim periods. All adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the accompanying condensed consolidated balance sheets and statements of income (operations) and comprehensive income (loss), stockholders’ equity and cash flows have been made. Although these interim financial statements do not include all of the information and footnotes required for complete annual financial statements, management believes the disclosures are adequate to make the information presented not misleading. These unaudited interim results of operations and cash flows for the six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the full year. These unaudited interim condensed consolidated financial statements and footnotes should be read in conjunction with the Company’s audited annual consolidated financial statements and footnotes included in its Annual Report on Form 10-K, as filed with the SEC on March 16, 2020, wherein a more complete discussion of significant accounting policies and certain other information can be found.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with GAAP and the rules and regulations of the SEC requires the use of estimates and assumptions, based on judgments considered reasonable, which affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates and assumptions on historical experience, known trends and events and various other factors that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Although management believes its estimates and assumptions are reasonable when made, they are based upon information available at the time they are made. Management evaluates the estimates and assumptions on an ongoing basis and, if necessary, makes adjustments. Due to the risks and uncertainties involved in the Company’s business and evolving market conditions, and given the subjective element of the estimates and assumptions made, actual results may differ from estimated results. The most significant estimates and judgments impact the fair value of intangible assets, goodwill and contingent consideration; income taxes (including the valuation allowance for deferred tax assets); research and development expenses; and going concern considerations.
Principles of Consolidation	Principles of ConsolidationThe Company’s consolidated financial statements include the accounts of the Company, its wholly owned subsidiary Viventia and its indirect subsidiaries, Viventia Bio USA Inc. and Viventia Biotech (EU) Limited. All intercompany transactions and balances have been eliminated in consolidation.
Foreign Currency Translation	Foreign Currency Translation The functional currency of the Company and each of its subsidiaries is the U.S. dollar.
Recent Accounting Pronouncements	Adopted in 2020 In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"). ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets held. The amendments in ASU 2016-13 eliminate the probable threshold for initial recognition of a credit loss in current GAAP and reflect an entity’s current estimate of all expected credit losses. ASU 2016-13 is effective for annual and interim periods beginning January 1, 2020 and is to be applied using a modified retrospective transition method. The Company adopted this guidance effective January 1, 2020, and it did not have a material impact on the Company’s financial position, results of operations or cash flows. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurements ("ASU 2018-13"). ASU 2018-13 modifies fair value measurement disclosure requirements. ASU 2018-13 is effective for annual and interim periods beginning after December 15, 2019. The Company adopted this guidance effective January 1, 2020, and although it resulted in some additional footnote disclosures, it did not have a material impact on the Company’s disclosures. For the new disclosures regarding our Level 3 instruments, please read Note 5, Fair Value Measurements and Financial Instruments, to these condensed consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15"). ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance to determine which implementation costs to defer and recognize as an asset. The effective date for ASU 2018-15 is for annual and interim periods beginning after December 15, 2019. The amendments in this ASU should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company adopted this guidance effective January 1, 2020, and it did not have a material impact on the Company’s financial position, results of operations or cash flows. Pending Adoption In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"). ASU 2019-12 simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments in ASU 2019-12 also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted. The method with which the amendments in this ASU are to be applied varies depending on the nature of the tax item impacted by amendment. Because the Company generates losses and pays no income taxes, it does not expect the adoption of ASU 2019-12 to have a material impact on the Company's financial position, results of operations or cash flows.

FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Summary of Carrying Amounts and Fair Values of Financial Instruments Measured


	June 30, 2020
					Fair Value Measurement Based on
	Carrying Amount		Fair Value		Quoted Prices in Active Markets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (cash equivalents)	$	31,339	$	31,339	$	31,339	$	—	$	—
Liabilities:
Contingent consideration	$	84,800	$	84,800	$	—	$	—	$	84,800


	December 31, 2019
					Fair Value Measurement Based on
	Carrying Amount		Fair Value		Quoted Prices in Active Markets (Level 1)		Significant other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (cash equivalents)	$	31,146	$	31,146	$	31,146	$	—	$	—
Liabilities:
Contingent consideration	$	120,020	$	120,020	$	—	$	—	$	120,020

Summary of Contingent Consideration Liability


Balance at December 31, 2019	$	120,020
Change in fair value of contingent consideration	(35,220)
Balance at June 30, 2020	$	84,800

INTANGIBLE ASSETS AND GOODWILL (Tables)

6 Months Ended

Jun. 30, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets

The following table sets forth the composition of intangible assets as of June 30, 2020 and December 31, 2019 (in thousands):


	June 30, 2020		December 31, 2019
IPR&D intangible assets:
Vicineum United States rights	$	31,700	$	31,700
Vicineum European Union rights	14,700		14,700
Total Intangibles	$	46,400	$	46,400

ACCRUED EXPENSES (Tables)

6 Months Ended

Jun. 30, 2020

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

The following table sets forth the composition of accrued expenses as of June 30, 2020 and December 31, 2019 (in thousands):


	June 30, 2020		December 31, 2019
Research and development	$	3,100	$	3,688
Payroll-related expenses	985		1,638
Severance to former Executives and other employees	66		378
Professional fees	692		378
Other	23		87
Total Accrued Expenses	$	4,866	$	6,169

STOCKHOLDERS' EQUITY (DEFICIT) (Tables)

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Summary of Common Stock

In addition, the Company had reserved for issuance the following amounts of shares of its common stock for the purposes described below as of June 30, 2020 and December 31, 2019 (in thousands):


	June 30, 2020	December 31, 2019
Shares of common stock issued	116,628	106,801
Shares of common stock reserved for issuance for:
Warrants	2,485	22,895
Stock options	9,990	6,236
Shares available for grant under 2014 Stock Incentive Plan	5,084	8,753
Shares available for sale under 2014 Employee Stock Purchase Plan	25	28
Total shares of common stock issued and reserved for issuance	134,212	144,713

Summary of Warrants Outstanding and Warrant Activity

The following table sets forth the Company's warrant activity for the six months ended June 30, 2020 (in thousands):


			Year-to-Date Warrant Activity
Issued	Exercise Price ⁽¹⁾	Expiration	December 31, 2019	Issued	(Exercised)	(Expired)	June 30, 2020
Jun-2019	$1.47	Jun-2020	20,410	—	—	(20,410)	—
Mar-2018	$0.55*	Mar-2023	1,943	—	—	—	1,943
Nov-2017	$0.55*	Nov-2022	487	—	—	—	487
May-2015	$11.83	Nov-2024	28	—	—	—	28
Nov-2014	$11.04	Nov-2024	27	—	—	—	27
			22,895	—	—	(20,410)	2,485

⁽¹⁾ As of June 30, 2020.

* Exercise price shown subject to further adjustment based on down round provision added by amendment.

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65888546&loc=d3e21300-112643

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
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+ Details

EARNINGS (LOSS) PER SHARE (Tables)

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Schedule of Earnings (Loss) Per Share

The following table illustrates the determination of earnings (loss) per share for each period presented:


	Three Months Ended June 30,										Six Months Ended June 30,
	2020		2019				2020				2019
	(in thousands, except per share amounts)
Basic Earnings (Loss) Per Share:
Numerator:
Net income (loss)	$	(26,344)			$	(54,335)			$	15,220			$	(60,815)
Less: Deemed dividend	(147)		—				(147)				—
Less: Income attributable to participating securities - basic	—		—				(322)				—
Net income (loss) attributable to common stockholders - basic	$	(26,491)	$	(54,335)			$	14,751			$	(60,815)

Denominator:
Weighted average common shares outstanding - basic	112,569		80,739				111,189				79,107

Net income (loss) per share applicable to common stockholders - basic	$	(0.24)	$	(0.67)			$	0.13			$	(0.77)


Dilutive Earnings (Loss) Per Share:
Numerator:
Net income (loss)	$	(26,344)	$	(54,335)			$	15,220			$	(60,815)
Less: Deemed Dividend	(147)		—				(147)				—
Less: Income attributable to participating securities - diluted	—		—				(2,473)
Net income (loss) attributable to common stockholders - diluted	$	(26,491)	$	(54,335)			$	12,600			$	(60,815)

Denominator:
Weighted average shares outstanding	112,569		80,739				111,189				79,107

Dilutive impact from:
Stock options and employee stock purchase plan	—		—				14				—
Weighted average common shares outstanding for diluted	112,569		80,739				111,203				79,107

Net income (loss) per share applicable to common stockholders - diluted	$	(0.24)	$	(0.67)			$	0.11			$	(0.77)

Schedule of Potentially Dilutive Securities Excluded from Diluted Loss Calculation


	Three Months Ended June 30,			Six Months Ended June 30,
	2020	2019	2020	2019
Warrants	2,485	5,779	55	5,779
Stock options	9,990	26,307	9,989	26,307
	12,475	32,086	10,044	32,086

SHARE-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Share-Based Compensation Expense


	Three Months ended June 30,						Six Months ended June 30,
	2020		2019		2020		2019
Research and development	$	91	$	86	$	171	$	139
General and administrative	400		269		727		543
	$	491	$	355	$	898	$	682

Schedule of Stock Option Activity


	Number of Shares under Option (in thousands)	Weighted-average Exercise Price per Option	Weighted-average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2019	6,236	$1.52	8.8	$	358
Granted	3,754	$0.87
Exercised	—	$0.00
Canceled or forfeited	—	$0.00
Outstanding at June 30, 2020	9,990	$1.27	9.0	$	—
Exercisable at June 30, 2020	2,866	$1.91	8.0	$	—

Schedule of Weighted-Average Inputs and Assumptions in Black-Scholes Option


	June 30, 2020	June 30, 2019
Fair value of common stock	$0.55	$0.63
Exercise price	$0.87	$0.93
Expected term (in years)	6.02	5.97
Risk-free interest rate	1.4	2.4
Expected volatility	71.3	78.0
Dividend yield	—%	—%

DESCRIPTION OF BUSINESS (Details) $ in Thousands	1 Months Ended		6 Months Ended		12 Months Ended
DESCRIPTION OF BUSINESS (Details) $ in Thousands	Apr. 30, 2018 patient	Sep. 30, 2016 USD ($) shares	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Variable Interest Entity [Line Items]
Number of patients \| patient	133
Number of operating segments \| segment			1
Cash and cash equivalents			$ 37,741		$ 48,121
Net working capital			35,000
Accumulated deficit			278,304		293,524
Negative cash flows from operating activities incurred			$ 18,326	$ 16,743	$ 37,500
Viventia Bio, Inc.
Variable Interest Entity [Line Items]
Shares of common stock issued to the selling shareholders (in shares) \| shares		4,000,000.0
Percentage of voting interests acquired (as a percent)		19.90%
One-time milestone payment upon first sale of product		$ 12,500
Period during which quarterly earn-outs are payable after date of net sales		15 years
Period in which acquiree is to use commercially reasonable efforts to achieve marketing authorizations		7 years
Viventia Bio, Inc. \| Vicinium \| Collaborative Arrangement, Revenue based on Specified Milestone
Variable Interest Entity [Line Items]
Percentage of net sales of quarterly earn-out payments during earn-out periods		2.00%
Viventia Bio, Inc. \| Vicinium \| Europe \| Collaborative Arrangement, Revenue based on Specified Milestone
Variable Interest Entity [Line Items]
One-time milestone payment upon first sale of product		$ 7,000
Viventia Bio, Inc. \| Vicinium \| Japan \| Collaborative Arrangement, Revenue based on Specified Milestone
Variable Interest Entity [Line Items]
One-time milestone payment upon first sale of product		$ 3,000

FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Liabilities:
Contingent consideration	$ 84,800	$ 120,020
Significant Unobservable Inputs (Level 3)
Liabilities:
Contingent consideration	84,800	120,020
Carrying Amount
Assets:
Money market funds (cash equivalents)	31,339	31,146
Liabilities:
Contingent consideration	84,800	120,020
Fair Value \| Recurring
Assets:
Money market funds (cash equivalents)	31,339	31,146
Liabilities:
Contingent consideration	84,800	120,020
Fair Value \| Recurring \| Quoted Prices in Active Markets (Level 1)
Assets:
Money market funds (cash equivalents)	31,339	31,146
Liabilities:
Contingent consideration	0	0
Fair Value \| Recurring \| Significant other Observable Inputs (Level 2)
Assets:
Money market funds (cash equivalents)	0	0
Liabilities:
Contingent consideration	0	0
Fair Value \| Recurring \| Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (cash equivalents)	0	0
Liabilities:
Contingent consideration	$ 84,800	$ 120,020

FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS - Summary of Changes in Fair Value of Contingent Consideration (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)	Dec. 31, 2019
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 120,020
Ending balance	$ 84,800
Contingent consideration liability measurements used	0.145	0.118
Royalty rate	2.00%
Unobservable Inputs (Level 3)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 120,020
Change in fair value of contingent consideration	(35,220)
Ending balance	$ 84,800
Discount Rate
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Weighted-average cost of capital	13.20%	5.60%

FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)	Dec. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liability measurements used	0.145	0.118
Royalty rate	2.00%
Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Change in fair value of contingent consideration	$ (35,220)
Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted-average cost of capital	13.20%	5.60%

INTANGIBLE ASSETS AND GOODWILL (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 13,064	$ 13,064
Vicinium \| IPR&D intangible assets
Finite-Lived Intangible Assets [Line Items]
Total Intangibles	46,400	46,400
Vicinium \| IPR&D intangible assets \| United States
Finite-Lived Intangible Assets [Line Items]
Total Intangibles	31,700	31,700
Vicinium \| IPR&D intangible assets \| Europe
Finite-Lived Intangible Assets [Line Items]
Total Intangibles	$ 14,700	$ 14,700

LEASES - Narrative (Details)	3 Months Ended		6 Months Ended
LEASES - Narrative (Details)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) ft² term	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Monthly rent			$ 21,400
Rent expense	$ 65,000	$ 53,000	$ 131,000	$ 129,000
Minimum
Lessee, Lease, Description [Line Items]
Lease term	4 months		4 months
Maximum
Lessee, Lease, Description [Line Items]
Lease term	9 months		9 months
Canada
Lessee, Lease, Description [Line Items]
Office space (in square feet) \| ft²			31,100
Renewal option \| term			1
Renewal term	5 years		5 years
Monthly rent			$ 12,800
Related operating expenses, per month			12,500
Operating lease cost, including related operating cost	$ 72,000	$ 71,000	$ 148,000	$ 146,000

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Research and development	$ 3,100	$ 3,688
Payroll-related expenses	985	1,638
Severance to former Executives and other employees	66	378
Professional fees	692	378
Other	23	87
Total Accrued Expenses	$ 4,866	$ 6,169

ACCRUED EXPENSES - Narrative (Details) - USD ($) $ in Thousands	Sep. 09, 2019	Aug. 02, 2019	Jun. 30, 2020	Dec. 31, 2019	Aug. 03, 2019
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Severance to former Executives and other employees			$ 66	$ 378
Former Chief Financial Officer
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Separation Agreement, period of separation payments and benefits agreed to	12 months
Severance to former Executives and other employees	$ 300
Former Chief Medical Officer
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Separation Agreement, period of separation payments and benefits agreed to		6 months
Severance to former Executives and other employees					$ 300
Separation payments		$ 200
Consulting fees and transition expenses					$ 100

STOCKHOLDERS' EQUITY (DEFICIT) - Equity Financing (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended			5 Months Ended	6 Months Ended
	Nov. 30, 2019	Jun. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2020	Jun. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Proceeds from sale of stock		$ 27.8
Sale of stock, shares issued (in shares)		20,400,000
Issuance of common stock, issuance costs			$ 0.1	$ 0.1	$ 2.2		$ 0.2
Number of warrants issued (in shares)								20,400,000
Combined purchase price (in dollars per share)								$ 1.47
Exercise price per warrant (in dollars per share)								$ 1.47
Warrants exercise period								1 year
ATM Facility
Class of Stock [Line Items]
Aggregate sales price	$ 35.0
Commission fixed rate	3.00%
Legal, accounting and printing costs						$ 0.2
Proceeds from sale of stock			$ 4.8				$ 8.0
Sale of stock, shares issued (in shares)			6,600,000				9,800,000
Stock price per share (in dollars per share)			$ 0.69				$ 0.75

STOCKHOLDERS' EQUITY (DEFICIT) - Preferred Stock (Details) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Equity [Abstract]
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0

STOCKHOLDERS' EQUITY (DEFICIT) - Common Stock (Details) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Equity [Abstract]
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares issued (in shares)	116,627,653	106,801,409
Common stock, shares outstanding (in shares)	116,627,653	106,801,409

STOCKHOLDERS' EQUITY (DEFICIT) - Summary of Common Stock Issued and Reserved for Issuance (Details) - shares	Jun. 30, 2020	Dec. 31, 2019
Class of Warrant or Right [Line Items]
Common stock, shares issued (in shares)	116,627,653	106,801,409
Shares of common stock reserved for issuance for:
Total shares of common stock issued and reserved for issuance (in shares)	134,212,000	144,713,000
Warrants
Shares of common stock reserved for issuance for:
Shares of common stock available for issuance (in shares)	2,485,000	22,895,000
Stock options
Shares of common stock reserved for issuance for:
Shares of common stock available for issuance (in shares)	9,990,000	6,236,000
Shares available for grant under 2014 Stock Incentive Plan
Shares of common stock reserved for issuance for:
Shares of common stock available for issuance (in shares)	5,084,000	8,753,000
Shares available for sale under 2014 Employee Stock Purchase Plan
Shares of common stock reserved for issuance for:
Shares of common stock available for issuance (in shares)	25,000	28,000

STOCKHOLDERS' EQUITY (DEFICIT) - Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2019	Mar. 31, 2018	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)							$ 1.47
Proceeds from sale of stock	$ 27,800
Less: Deemed dividend			$ 147	$ 0	$ 147	$ 0
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)					22,895,000
Warrants Issued (in shares)					0
Warrants Exercised (in shares)					0
Warrants Expired (in shares)						(20,410,000)
Warrants outstanding, ending balance (in shares)			2,485,000		2,485,000
Common Stock
Class of Warrant or Right [Line Items]
Proceeds from sale of stock		$ 9,000
Warrant Or Right Outstanding [Roll Forward]
Warrants Exercised (in shares)				(3,361,115)
Warrants, Expiring June 2020
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)			$ 1.47		$ 1.47
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)					20,410,000
Warrants Issued (in shares)					0
Warrants Exercised (in shares)					0
Warrants Expired (in shares)						(20,410,000)
Warrants outstanding, ending balance (in shares)			0		0
Warrants, Expiring March 2023
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)			$ 0.55		$ 0.55
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)					1,943,000
Warrants Issued (in shares)					0
Warrants Exercised (in shares)					0
Warrants Expired (in shares)						0
Warrants outstanding, ending balance (in shares)			1,943,000		1,943,000
Warrants, Expiring November 2022
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)			$ 0.55		$ 0.55
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)					487,000
Warrants Issued (in shares)					0
Warrants Exercised (in shares)					0
Warrants Expired (in shares)						0
Warrants outstanding, ending balance (in shares)			487,000		487,000
Warrants, Expiring November 2024
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)			$ 11.83		$ 11.83
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)					28,000
Warrants Issued (in shares)					0
Warrants Exercised (in shares)					0
Warrants Expired (in shares)						0
Warrants outstanding, ending balance (in shares)			28,000		28,000
Warrants, Expiring November 2024
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)			$ 11.04		$ 11.04
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)					27,000
Warrants Issued (in shares)					0
Warrants Exercised (in shares)					0
Warrants Expired (in shares)						0
Warrants outstanding, ending balance (in shares)			27,000		27,000
2018 Warrant Amendment Agreement
Class of Warrant or Right [Line Items]
Exercise price (in dollars per share)		$ 1.20	$ 0.55		$ 0.55
Reduction in warrant exercise price (in dollars per share)		$ 0.95

STOCKHOLDERS' EQUITY (DEFICIT) - Stock Options and Employee Stock Purchase Plan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity [Abstract]
Compensation expense related to vested awards	$ 491	$ 355	$ 898	$ 682

EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income (loss)	$ (26,344)	$ 41,564	$ (54,335)	$ (6,480)	$ 15,220	$ (60,815)
Less: Deemed dividend	(147)		0		(147)	0
Less: Income attributable to participating securities - basic	0		0		(322)	0
Net Income (Loss) Available to Common Stockholders, Basic	$ (26,491)		$ (54,335)		$ 14,751	$ (60,815)
Weighted-average common shares outstanding - basic (in shares)	112,569		80,739		111,189	79,107
Net income (loss) per share applicable to common stockholders - basic (in dollars per share)	$ (0.24)		$ (0.67)		$ 0.13	$ (0.77)
Less: Income attributable to participating securities - diluted	$ 0		$ 0		$ (2,473)
Net Income (Loss) Available to Common Stockholders, Diluted	$ (26,491)		$ (54,335)		$ 12,600	$ (60,815)
Stock options and employee stock purchase plan (in shares)	0		0		14	0
Weighted-average common shares outstanding - diluted (in shares)	112,569		80,739		111,203	79,107
Net income (loss) per share applicable to common stockholders - diluted (in dollars per share)	$ (0.24)		$ (0.67)		$ 0.11	$ (0.77)

EARNINGS (LOSS) PER SHARE - Antidilutive (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net (loss) income per share (in shares)	12,475,000	32,086,000	10,044,000	32,086,000
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net (loss) income per share (in shares)	2,485,000	5,779,000	55,000	5,779,000
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net (loss) income per share (in shares)	9,990,000	26,307,000	9,989,000	26,307,000

SHARE-BASED COMPENSATION - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 491	$ 355	$ 898	$ 682
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	91	86	171	139
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 400	$ 269	$ 727	$ 543

SHARE-BASED COMPENSATION - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding (in shares)	9,990		9,990		6,236
Share-based compensation expense	$ 491	$ 355	$ 898	$ 682
Unrecognized compensation cost, non-vested stock options	$ 4,400		$ 4,400
Weighted-average period to recognize non-vested stock options			2 years 10 months 24 days
Weighted-average grant-date fair value of stock options granted (in dollars per share)			$ 0.55	$ 0.63
Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding (in shares)	2,200		2,200
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for issuance (in shares)	9,990		9,990		6,236
2014 Stock Incentive Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
Period exercisable from date of grant			10 years
Stock options outstanding (in shares)	7,700		7,700
Shares of common stock available for issuance (in shares)	5,100		5,100
2014 Stock Incentive Plan \| Vesting on the First Anniversary of Date of Grant \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, vesting rate			25.00%
2014 Stock Incentive Plan \| Vesting at End of Each Successive Three-Month Period Thereafter \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, vesting rate			6.25%
2009 Stock Incentive Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period exercisable from date of grant			10 years
Vested stock options outstanding (in shares)			100

SHARE-BASED COMPENSATION - Stock Options (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Number of Shares under Option (in thousands)
Outstanding at beginning of period (in shares)	6,236	6,236
Granted (in shares)		3,754
Exercised (in shares)		0
Canceled or forfeited (in shares)		0
Outstanding at end of period (in shares)		9,990
Exercisable at end of period (in shares)		2,866
Weighted-average Exercise Price per Option
Outstanding at beginning of period (in dollars per share)	$ 1.52	$ 1.52
Granted (in dollars per share)		0.87
Exercised (in dollars per share)		0.00
Canceled or forfeited (in dollars per share)		0.00
Outstanding at end of period (in dollars per share)		1.27
Exercisable (in dollars per share)		$ 1.91
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average Remaining Contractual Life (in years), Outstanding	8 years 9 months 18 days	9 years
Weighted-average Remaining Contractual Life (in years), Exercisable		8 years
Aggregate Intrinsic Value, Outstanding		$ 0	$ 358
Aggregate Intrinsic Value, Exercisable		$ 0

SHARE-BASED COMPENSATION - Weighted-Average Inputs and Assumptions (Details) - $ / shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Fair value of common stock (in dollars per share)	$ 0.55	$ 0.63
Exercise price (in dollars per share)	$ 0.87	$ 0.93
Expected term (in years)	6 years 7 days	5 years 11 months 19 days
Risk-free interest rate	1.40%	2.40%
Expected volatility	71.30%	78.00%
Dividend yield	0.00%	0.00%

EMPLOYEE BENEFIT PLANS (Details) - USD ($) shares in Thousands	6 Months Ended
	Jun. 30, 2020	Feb. 28, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution retirement plan, maximum employee contribution deferred	75.00%
Discretionary match per participating employee, maximum	$ 4,000
Employer matching contribution, percent of employees' eligible compensation	4.00%
2014 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for issuance (in shares)		200
Common stock purchase price, discount rate	15.00%
Common stock available for sale (in shares)	25

LICENSE AGREEMENTS (Details) € in Thousands, $ in Thousands	1 Months Ended			6 Months Ended
LICENSE AGREEMENTS (Details) € in Thousands, $ in Thousands	Sep. 30, 2016 USD ($)	Aug. 31, 2016 USD ($)	Jun. 30, 2016 USD ($) option	Jun. 30, 2020 USD ($)	Jun. 30, 2020 EUR (€)
Organization And Basis Of Presentation [Line Items]
Royalty rate				2.00%	2.00%
University of Zurich
Organization And Basis Of Presentation [Line Items]
License agreement, royalty on net product sales, percentage				4.00%	4.00%
License agreement, rate requiring reduction in the amount of royalties owed				10.00%	10.00%
License agreement, royalty on net product sales, minimum				2.00%	2.00%
University of Zurich \| Collaborative Arrangement, Revenue Based on Clinical Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone				$ 750
Micromet AG
Organization And Basis Of Presentation [Line Items]
License agreement, royalty on net product sales, percentage				3.50%	3.50%
Potential milestone payments \| €					€ 3,600
License Agreement, royalty payment, reduction, conditions not met				1.50%	1.50%
License maintenance fees \| €					€ 50
XOMA Ireland Limited
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone				$ 250
License agreement, royalty on net product sales, percentage				2.50%	2.50%
License agreement, rate requiring reduction in the amount of royalties owed				50.00%	50.00%
License agreement, royalty on net product sales, minimum				1.75%	1.75%
Roche
Organization And Basis Of Presentation [Line Items]
Up-front license fee		$ 7,500
Additional up-front fee		262,500
License agreement, option periods \| option			2
License agreement, buyout amount under first option period			$ 135,000
License agreement, period to pay buyout option once exercised			30 days
License agreement, buyout amount under second option period			$ 265,000
License agreement, buyout amount under second option period, upon non-issuance of patent rights or licensed product			$ 220,000
License agreement, period for termination where sufficient development activities are not performed			12 months
Roche \| First Indication
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		197,500
Roche \| Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		72,500
Roche \| Collaborative Arrangement, Revenue Based on Regulatory Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		50,000
Roche \| Collaborative Arrangement, Revenue Based on Commercialization Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone		$ 75,000
Roche \| Second Indication
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone				$ 65,000
Roche \| EBI-031 \| Minimum
Organization And Basis Of Presentation [Line Items]
Royalty rate				7.50%	7.50%
Roche \| EBI-031 \| Maximum
Organization And Basis Of Presentation [Line Items]
Royalty rate				15.00%	15.00%
Roche \| EBI-031 \| Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
License agreement, amount payable upon achievement of specified milestone	$ 22,500
Roche \| IL-6
Organization And Basis Of Presentation [Line Items]
Royalty rate				50.00%	50.00%

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Director \| Protoden Intellectual Property
Related Party Transaction [Line Items]
Amount of related party transaction			$ 0.1	$ 0.1
Annual fee under license agreement			0.1
Majority Shareholder \| Rent Expense Associated With Lease [Member]
Related Party Transaction [Line Items]
Amount of related party transaction	$ 0.1	$ 0.1	$ 0.1	$ 0.1

SUBSEQUENT EVENT - Narrative (Details) - Subsequent Event - Qilu Pharmaceutical Co., Ltd. - Licensing Agreements $ in Thousands	Jul. 30, 2020 USD ($)
Subsequent Event [Line Items]
Cash payment	$ 12,000
Total milestone payments	$ 23,000
Royalty payment based on annual net sales	12.00%