Carisma Therapeutics (CARM) 10-Q 10 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 08, 2019
Document And Entity Information [Abstract]
Trading Symbol	SESN
Entity Registrant Name	Sesen Bio, Inc.
Entity Central Index Key	0001485003
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Transition Period Flag	true
Entity Common Stock, Shares Outstanding		77,464,781

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 42,437	$ 50,422
Prepaid expenses and other current assets	3,014	1,334
Total current assets	45,451	51,756
Property and equipment, net	272	321
Restricted cash	20	20
Intangible assets	46,400	46,400
Goodwill	13,064	13,064
Other assets	232	0
Total assets	105,439	111,561
Current liabilities:
Accounts payable	1,683	1,367
Accrued expenses	5,234	4,746
Other current liabilities	136	0
Total current liabilities	7,053	6,113
Other liabilities	398	313
Deferred tax liability	12,528	12,528
Contingent consideration	47,400	48,400
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 shares authorized at March 31, 2019 and December 31, 2018 and no shares issued and outstanding at March 31, 2019 and December 31, 2018	0	0
Common stock, $0.001 par value per share; 200,000,000 shares authorized at March 31, 2019 and December 31, 2018 and 77,464,781 and 77,456,180 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	77	77
Additional paid-in capital	230,487	230,154
Accumulated deficit	(192,504)	(186,024)
Total stockholders’ equity	38,060	44,207
Total liabilities and stockholders’ equity	$ 105,439	$ 111,561

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD 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 USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	77,464,781	77,456,180
Common stock, shares outstanding (in shares)	77,464,781	77,456,180

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating expenses:
Research and development	$ 4,686	$ 3,255
General and administrative	3,055	1,952
Gain from change in fair value of contingent consideration	(1,000)	(1,200)
Total operating expenses	6,741	4,007
Loss from operations	(6,741)	(4,007)
Other income:
Other income, net	261	44
Total other income, net	261	44
Net loss and comprehensive loss	$ (6,480)	$ (3,963)
Net loss per share — basic and diluted (in dollars per share)	$ (0.08)	$ (0.11)
Weighted-average number of common shares used in net loss per share- basic and diluted (in shares)	77,458	35,674

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		34,702,565
Beginning balance at Dec. 31, 2017	$ 18,034	$ 35	$ 170,330	$ (152,331)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		43,105,466
Exercise of stock options and vesting of restricted stock awards	0		0
Exercise of stock options and vesting of restricted stock awards (in shares)		4,430
Issuance of common stock pursuant to the 2014 ESPP	10		10
Issuance of common stock pursuant to the 2014 ESPP (in shares)		9,565
Exercise of common stock warrants	$ 336	$ 0	336
Exercise of common stock warrants (in shares)	420,778
Issuance of common stock and common stock warrants, net of issuance costs	$ 9,040	$ 8	9,032
Issuance of common stock and common stock warrants, net of issuance costs (in shares		7,968,128
Stock-based compensation expense	401		401
Net loss	(3,963)			(3,963)
Ending balance at Mar. 31, 2018	23,858	$ 43	180,109	(156,294)
Ending balance (in shares) at Mar. 31, 2018		43,105,466
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		43,105,466
Beginning balance (in shares)		77,456,180
Beginning balance at Dec. 31, 2018	$ 44,207	$ 77	230,154	(186,024)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		77,464,781
Exercise of stock options and vesting of restricted stock awards (in shares)	0
Issuance of common stock pursuant to the 2014 ESPP	$ 7		7
Issuance of common stock pursuant to the 2014 ESPP (in shares)		8,601
Stock-based compensation expense	326		326
Net loss	(6,480)			(6,480)
Ending balance at Mar. 31, 2019	$ 38,060	$ 77	$ 230,487	$ (192,504)
Ending balance (in shares) at Mar. 31, 2019		77,464,781
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		77,464,781

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net loss	$ (6,480,000)	$ (3,963,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	49,000	49,000
Stock-based compensation expense	326,000	401,000
Change in fair value of warrant liability	0	0
Gain from change in fair value of contingent consideration	(1,000,000)	(1,200,000)
Gain on sale of equipment	0	(5,000)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,912,000)	(236,000)
Accounts payable	316,000	486,000
Accrued expenses and other liabilities	709,000	85,000
Net cash used in operating activities	(7,992,000)	(4,383,000)
Investing activities
Sales of equipment	0	5,000
Net cash provided by investing activities	0	5,000
Financing activities
Proceeds from issuance of common stock and the issuance and exercise of common stock warrants, net of issuance costs	0	9,376,000
Proceeds from sale of common stock pursuant to 2014 ESPP	7,000	10,000
Net cash provided by financing activities	7,000	9,386,000
Net increase (decrease) in cash, cash equivalents and restricted cash	(7,985,000)	5,008,000
Cash, cash equivalents and restricted cash at beginning of period	50,442,000	14,690,000
Cash, cash equivalents and restricted cash at end of period	42,457,000	19,698,000
Supplemental non-cash operating activities
Right-of-use assets obtained in exchange for new operating lease	236,480,000	0
Cash paid for amounts included in the measurement of liabilities	$ 38,202,000	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Sesen Bio, Inc. (the “Company”), a Delaware corporation, is a late-stage clinical company developing targeted fusion protein therapeutics ("TFPTs") composed of an anti-cancer antibody fragment tethered to a protein toxin for the treatment of cancer. The Company genetically fuses the cancer-targeting antibody fragment and the cytotoxic protein payload into a single molecule which is produced through the Company's proprietary one-step manufacturing process. The Company targets tumor cell surface antigens with limited expression on normal cells. Binding of the target antigen by the TFPT allows for rapid internalization into the targeted cancer cell. The Company has designed its targeted fusion proteins to overcome the fundamental efficacy and safety challenges inherent in existing antibody-drug conjugates ("ADCs"), where a payload is chemically attached to a targeting antibody. Basis of presentation The condensed consolidated financial statements as of March 31, 2019 and December 31, 2018 and for the three months ended March 31, 2019 and 2018 and the related information contained within the notes to the condensed consolidated financial statements are unaudited. The unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting standards applicable to interim financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s consolidated financial position as of March 31, 2019 , its results of operations for the three months ended March 31, 2019 and 2018, its statement of shareholders' equity for the three months ended March 31, 2019 and 2018, and its cash flows for the three months ended March 31, 2019 and 2018. The financial data and the other financial information disclosed in these notes to the condensed consolidated financial statements related to the three -month periods are also unaudited. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any other future annual or interim period. The condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 that was filed with the Securities and Exchange Commission (“SEC”) on March 1, 2019 (the "2018 Form 10-K"). The condensed consolidated financial statements include the accounts of the Company, its wholly owned subsidiary, Viventia Bio Inc. ("Viventia"), and its indirect subsidiaries, Viventia Bio USA Inc. and Viventia Biotech (EU) Limited. All inter-company transactions and balances have been eliminated in consolidation. The condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles. The functional currency of Viventia, Viventia Bio USA Inc. and Viventia Biotech (EU) Limited is the U.S. dollar. Liquidity The Company has financed its operations to date primarily through private placements of its common stock and preferred stock, and convertible bridge notes, venture debt borrowings, its initial public offering ("IPO"), follow-on public offerings, sales effected in an "at-the-market" offering, and the License Agreement (the "License Agreement") with F. Hoffmann La-Roche Inc. (collectively, "Roche"). As of March 31, 2019 , the Company had cash and cash equivalents totaling $ 42.4 million , net working capital of $ 38.4 million and an accumulated deficit of $ 192.5 million . The future success of the Company is dependent on its ability to develop its product candidates and ultimately upon its ability to attain profitable operations. In order to commercialize its product candidates, 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 with favorable terms, development by its competitors of new technological innovations, protection of proprietary technology and market acceptance of the Company’s products. The successful discovery and development of product candidates requires substantial working capital which may not be available to the Company on favorable terms or not at all. To date, the Company has no revenue from product sales and management expects continuing operating losses in the future. As of March 31, 2019 , the Company had available cash and cash equivalents of $ 42.4 million , which it does not believe is sufficient to fund the Company’s current operating plan for at least the next twelve months after the date of this Form 10-Q filing. 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 and, if necessary, the Company will be required to implement cost reduction strategies. These factors raise substantial doubt about the Company’s ability to continue as a going concern. The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The condensed consolidated financial statements 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.

Significant Accounting Policies

Significant Accounting Policies and Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies and Recent Accounting Pronouncements	Significant Accounting Policies and Recent Accounting Pronouncements Recently adopted accounting standards In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). ASU 2016-02 addresses the financial reporting of leasing transactions. Under past guidance for lessees, leases are only included on the balance sheet if certain criteria, classifying the agreement as a capital lease, are met. This update requires the recognition of a right-of-use asset and a corresponding lease liability, discounted to the present value, for all leases that extend beyond 12 months. For operating leases, the asset and liability are expensed over the lease term on a straight-line basis, with all cash flows included in the operating section of the statement of cash flows. For finance leases, interest on the lease liability is recognized separately from the amortization of the right-of-use asset in the statement of operations and the repayment of the principal portion of the lease liability is classified as a financing activity while the interest component is included in the operating section of the statement of cash flows. This guidance is effective for annual and interim reporting periods beginning after December 15, 2018 including interim periods within those fiscal years. In July 2018, the FASB issued ASU No. 2018-10, Leases (Topic 842), Codification Improvements (“ASU 2018-10”), ASU No. 2018-11, Leases (Topic 842), Targeted Improvements (“ASU 2018-11”) , and ASU No. 2019-01 Leases (Topic 842), Codification Improvements to provide additional guidance for the adoption Accounting Standards Codification (“ASC”) of Topic 842, Leases (“ASC 842”) . ASU 2018-10 clarifies certain provisions and corrects unintended applications of the guidance, such as the rate implicit in a lease, impairment of the net investment in a lease, lessee reassessment of lease classifications, lessor reassessment of lease term and purchase options, variable payments that depend on an index or rate and certain transition adjustments. The amendments in ASU 2018-11 allow for an additional transition method, whereby at the adoption date the entity recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption, while the comparative period disclosures continue recognition under ASC 840, Leases (“ASC 840”). Additionally, ASU 2018-11 includes a practical expedient for separating contract components for lessors . The Company adopted ASC 842 using the optional transition method outlined in ASU 2018-11 as of January 1, 2019. The adoption of ASC 842 resulted in the recognition of operating lease right-of-use assets of approximately $236,000 and corresponding lease liabilities of approximately $236,000 . The adoption of these ASUs did not have a material impact on the Company’s financial condition or results of operations, however, the adoption resulted in significant changes to the Company’s financial statement disclosures. In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairmen t ("ASU 2017-04"). ASU 2017-04 simplifies the accounting for goodwill impairment by removing Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. ASU 2017-04 is effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019, and should be applied on a prospective basis. The Company adopted this guidance effective January 1, 2019. We do not expect an impact upon adoption of ASU 2017-04 on our condensed consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718) (“Topic 718”): Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). ASU 2018-07 expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees, and as a result, the accounting for share-based payments to non-employees will be substantially aligned. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company adopted this standard effective during the three months ended March 31, 2019. The adoption of ASU 2018-07 did not have a material impact on the Company’s financial position or results of operations. In July 2018, the FASB issued ASU No. 2018-09, “Codification Improvements” (“ASU 2018-09”). ASU 2018-09 provides amendments to a wide variety of topics in the FASB’s Accounting Standards Codification, which applies to all reporting entities within the scope of the affected accounting guidance. The transition and effective date guidance are based on the facts and circumstances of each amendment. Some of the amendments in ASU 2018-09 do not require transition guidance and were effective upon issuance of ASU 2018-09. However, many of the amendments do have transition guidance with effective dates for annual periods beginning after December 15, 2018. ASU 2018-09 did not have a material impact on the Company’s financial statements and related disclosures. Recently issued accounting pronouncements In August 2018, the FASB issued ASU 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. The effective date for ASU 2018-13 is for annual and interim periods beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the impact ASU 2018-13 will have on its consolidated financial statements. In August 2018, the FASB issued ASU 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 Company is currently evaluating the impact ASU 2018-15 will have on its consolidated financial statements. In June 2016, the FASB issued ASU 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 interim and annual reporting periods beginning January 1, 2020, and is to be applied using a modified retrospective transition method. Earlier adoption is permitted. The Company is currently evaluating the impact ASU 2016-13 will have on its consolidated financial statements. Critical accounting policies The Company’s significant accounting policies are described in Note 2, Significant Accounting Policies , in the 2018 Annual Report on Form 10-K. During the three months ended March 31, 2019, the Company adopted the following additional significant accounting policies: Leases Effective January 1, 2019, the Company adopted ASC 842 using the optional transition method. The adoption of ASC 842 represents a change in accounting principle that aims to increase transparency and comparability among organizations by requiring the recognition of right-of-use assets and lease liabilities on the balance sheet for both operating and finance leases. In addition, the standard requires enhanced disclosures that meet the objective of enabling financial statement users to assess the amount, timing, and uncertainty of cash flows arising from leases. The reported results for the three months ended March 31, 2019 reflect the application of ASC 842 guidance, while the reported results for prior periods were prepared in conjunction with ASC 840. As part of the ASC 842 adoption, the Company utilized certain practical expedients outlined in the guidance. These practical expedients include: • Accounting policy election to use the short-term lease exception by asset class; • Election of the practical expedient package during transition, which includes: ◦ An entity need not reassess whether any expired or existing contracts are or contain leases. ◦ An entity need not reassess the classification for any expired or existing leases. As a result, all leases that were classified as operating leases in accordance with ASC 840 are classified as operating leases under ASC 842, and all leases that were classified as capital leases in accordance with ASC 840 are classified as finance leases under ASC 842. ◦ An entity need not reassess initial direct costs for any existing leases. ◦ An entity need not separate out non-lease components from lease components, for all classes of underlying assets The Company’s lease portfolio as of the adoption date includes: a property lease for its manufacturing facility, a property lease for its headquarters in Cambridge, MA, and a property lease for office space in Philadelphia, PA. The Company determines if an arrangement is a lease at the inception of the contract. The asset components of the Company’s operating leases are recorded as operating lease right-of-use assets and reported within Other assets in the Company's condensed consolidated balance sheets. The short term and long term liability components are recorded in Other current liabilities and Other liabilities, respectively, in the Company’s condensed consolidated balance sheets. As of March 31, 2019, the Company did not have any finance leases. Right-of-use assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term at the commencement date. Existing leases in the Company’s lease portfolio as of the adoption date were valued as of January 1, 2019. The Company uses an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments, if an implicit rate of return is not provided with the lease contract. Operating lease right-of-use assets are adjusted for incentives received. Operating lease costs are recognized on a straight-line basis over the lease term, in accordance with ASC 842, and also includes variable operating costs incurred during the period. Lease costs also include amounts related to short term leases.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three broad levels as follows: Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly; and Level 3 inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following table presents information about the Company’s financial assets and liabilities that have been measured at fair value, and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value. The Company determines the fair value of contingent consideration using Level 3 inputs. The following table summarizes the assets and liabilities measured at fair value on a recurring basis at March 31, 2019 (in thousands): Description March 31, Active Markets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets: Cash and cash equivalents $ 42,437 $ 42,437 $ — $ — Restricted cash 20 20 — — Total assets $ 42,457 $ 42,457 $ — $ — Liabilities: Contingent consideration 47,400 — — 47,400 Total liabilities $ 47,400 $ — $ — $ 47,400 The following table summarizes the assets and liabilities measured at fair value on a recurring basis at December 31, 2018 (in thousands): Description December 31, 2018 Active Markets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets: Cash and cash equivalents $ 50,422 $ 50,422 $ — $ — Restricted cash 20 20 — — Total assets $ 50,442 $ 50,442 $ — $ — Liabilities: Contingent consideration 48,400 — — 48,400 Total liabilities $ 48,400 $ — $ — $ 48,400 Contingent consideration In 2016, the Company acquired Viventia through the issuance of common stock and contingent consideration (the "Acquisition"), pursuant to the terms of a share purchase agreement (the "Share Purchase Agreement"). The Company has valued the acquired assets and liabilities based on their estimated fair values as of September 20, 2016 and finalized its purchase accounting for the Acquisition during the third quarter of 2017. The contingent consideration relates to amounts potentially payable to Viventia's shareholders pursuant to the terms of the Share Purchase Agreement. Contingent consideration is measured at fair value and is based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The valuation of contingent consideration uses assumptions the Company believes would be made by a market participant. The Company assesses these estimates on an on-going basis as additional data impacting the assumptions is obtained. Future changes in the fair value of contingent consideration related to updated assumptions and estimates are recognized within the condensed consolidated statements of operations and comprehensive loss. Contingent consideration may change significantly as development progresses and additional data are obtained, impacting the Company’s assumptions regarding probabilities of successful achievement of related milestones used to estimate the fair value of the liability and the timing in which they are expected to be achieved. In evaluating the fair value information, considerable judgment is required to interpret the market data used to develop the estimates. The estimates of fair value may not be indicative of the amounts that could be realized in a current market exchange. Accordingly, the use of different market assumptions and/or different valuation techniques could result in materially different fair value estimates. The following table sets forth a summary of changes in the fair value of the Company's contingent consideration liability (in thousands): Beginning balance, December 31, 2018 $ 48,400 Gain from change in fair value of contingent consideration (1,000 ) Ending balance, March 31, 2019 $ 47,400 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, the level of commercial sales of Vicinium ® , and discount rates ranging from 6.6% to 13.7% as of December 31, 2018 and 6.2% to 11.7% as of March 31, 2019 . Significant changes in any of these assumptions would result in a significantly higher or lower fair value measurement. There have been no changes to the valuation methods utilized during the three months ended March 31, 2019 . The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between levels during the three months ended March 31, 2019 .

License Agreement with Roche

License Agreement with Roche	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License Agreement with Roche	License Agreement with Roche On June 10, 2016, the Company entered into the License Agreement with Roche, which became effective on August 16, 2016. Under the License Agreement, 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 or all other IL-6 antagonistic anti-IL-6 monoclonal antibodies , to make, have made, use, have used, register, have registered, sell, have sold, offer for sale, import and export any product containing such an antibody or any companion diagnostic used to predict or monitor response to treatment with such a product (collectively, the “Licensed Intellectual Property”). During 2016, the Company received an upfront license fee of $7.5 million and a milestone payment of $22.5 million . The Company is entitled to receive up to $240.0 million in additional consideration upon the achievement of specified regulatory, development and commercial milestones. Specifically, an aggregate amount of up to $175.0 million is payable to the Company for the achievement of specified milestones with respect to the first indication: $50.0 million in development milestones, $50.0 million in regulatory milestones and $75.0 million in commercialization milestones. 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% for 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 buy-out options. The License Agreement is subject to the provisions of Accounting Standards Codification 606, Revenue from Contracts with Customers (" ASC 606"), which was adopted effective January 1, 2018 utilizing a modified retrospective method. The Company concluded that all performance obligations had been achieved as of the adoption date and therefore the full transaction price was considered earned. The transaction price was determined to be the $30.0 million received in 2016. Additional consideration to be paid to the Company upon the achievement of certain milestones will be included if it is expected that the amounts will be received and the amounts would not be subject to a constraint. As of the date of the adoption, no amounts were expected to be received from the achievement of any milestones due to the nature of the milestones and the development status of the product candidates at the time of the adoption. As a result, there were no amounts required to be recorded as a cumulative adoption adjustment as the consideration recognized under ASC 606 was consistent with the amounts recognized under the previous accounting literature. As of March 31, 2019 and March 31, 2018, the Company concluded that there would be no adjustments to the transaction price as the Company continued to not expect any amounts to be received from any milestones within the License Agreement. This is due to the nature of the milestones and the development status of the product candidates as of the end of each reporting period. As a result, no revenue was recognized during the three-month periods ended March 31, 2019 and March 31, 2018 as all performance obligations had been previously achieved and there was no change in the transaction price during the period.

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2019
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consisted of the following (in thousands): March 31, December 31, 2018 Development costs $ 3,542 $ 2,928 Employee compensation 491 1,045 Severance to former CEO and other employees 610 278 Professional fees 519 464 Other 72 31 $ 5,234 $ 4,746 Stephen A. Hurly departed as the President and Chief Executive of the Company, effective as of August 7, 2018. In connection with his departure, Mr. Hurly and the Company entered into a separation agreement and general release, dated September 28, 2018 (the “Separation Agreement”), which sets forth the terms of Mr. Hurly’s separation from the Company. Pursuant to the Separation Agreement, which includes Mr. Hurly's agreement to a release of claims and complying with certain other continuing obligations contained therein, the Company is obligated to pay Mr. Hurly a total amount of $637,500 , less applicable withholdings and deductions, which consists of the equivalent of twelve months of Mr. Hurly’s base salary ( $425,000 ) immediately prior to his departure and Mr. Hurly’s annual target bonus for 2018 ( $212,500 ). In addition, the Company, to the extent allowed by applicable law and the applicable plan documents, will continue to provide Mr. Hurly and certain of his dependents with group health and dental insurance for a period of up to twelve months after the effective date of the Separation Agreement. Accrued severance related to this agreement is $158,000 for the period ended March 31, 2019. The remaining amounts of accrued severance as of March 31, 2019 relate to terminations of other employees within the period.

Shareholder Equity

Shareholder Equity	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Shareholder Equity	Shareholder Equity Equity Financings During the three months ended March 31, 2018, the Company raised approximately $9.0 million of net proceeds from the sale of 7,968,128 shares of common stock at a price of $1.13 per share in a registered direct public offering and the sale of common stock purchase warrants to purchase 7,968,128 shares of common stock at a price of $0.125 per warrant in a concurrent private placement (collectively, the “March 2018 Financing”). Subject to certain ownership limitations, the common stock purchase warrants issued in the March 2018 Financing were exercisable immediately upon issuance at an exercise price equal to $1.20 per share of common stock, subject to adjustments as provided under the terms of such common stock purchase warrants. The common stock purchase warrants are exercisable for five years from March 23, 2018. In addition, during the three months ended March 31, 2018, the Company received proceeds of $0.3 million from the issuance of 420,778 shares of its common stock upon the cash exercise of common stock purchase warrants issued in connection with its underwritten public offering in November 2017. Pursuant to the terms of the Company's 2014 Stock Incentive Plan (the "2014 Plan"), the number of shares authorized for issuance automatically increases on the first day of each fiscal year. On January 1, 2019, the number of shares reserved for issuance under the 2014 Plan increased by 1,102,362 shares. As of March 31, 2019 , the total number of shares of common stock available for issuance under the 2014 Plan was 1,319,184 . Share-Based Payments In September 2016, the Company issued 650,000 inducement equity awards outside the 2014 Plan in accordance with Nasdaq Listing Qualifications Department (“Nasdaq”) Listing Rule 5635(c)(4). The inducement equity awards were approved and recommended by the Company's Compensation Committee, approved by the Board of Directors and were made as an inducement material to certain individuals’ acceptance of employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4). In August 2018, the Company issued 1,350,000 inducement equity awards outside the 2014 Plan in accordance with Nasdaq Listing Rule 5635(c)(4). The inducement equity awards were approved and recommended by the Company's Compensation Committee, approved by the Board of Directors and were made as an inducement material to Dr. Cannell’s acceptance of employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4). In December 2018, the Company issued 425,000 inducement equity awards outside the 2014 Plan in accordance with Nasdaq Listing Rule 5635(c)(4). The inducement equity awards were approved and recommended by the Company's Compensation Committee, approved by the Board of Directors and were made as an inducement material to Dr. Kim’s acceptance of employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4). As of March 31, 2019, the total amount of shares outstanding classified as inducement awards was 1,937,500 . The Company also maintains the Company's 2009 Stock Incentive Plan, as amended and restated, and the Company's 2014 Employee Stock Purchase Plan (the "2014 ESPP"). Stock-Based Compensation Expense Stock-based compensation expense by award type was as follows (in thousands): Three Months Ended 2019 2018 Stock options $ 325 $ 375 Restricted stock — 23 Employee stock purchase plan 1 3 $ 326 $ 401 The Company allocated stock-based compensation expense as follows in the condensed consolidated statements of operations and comprehensive loss (in thousands): Three Months Ended 2019 2018 Research and development expense $ 52 $ 165 General and administrative expense 274 236 $ 326 $ 401 At March 31, 2019 , there was $3.4 million of total unrecognized compensation expense related to unvested stock options for employee and non-employee consultants and shares issued pursuant to the 2014 ESPP. This unrecognized compensation expense is expected to be recognized over a weighted-average period of 3.33 years. Stock Options A summary of the stock option activity is presented below: Shares Weighted-Average Exercise Price Outstanding at December 31, 2018 3,941,947 $ 2.12 Granted 2,110,115 0.85 Exercised — — Cancelled or forfeited (363,500 ) 2.44 Outstanding at March 31, 2019 5,688,562 $ 1.62 Exercisable at March 31, 2019 1,076,840 $ 3.13 In October 2017, the Company issued stock option awards to certain employees which contained performance vesting conditions. These options vested in installments based on the achievement of certain strategic and clinical milestones. In January 2018, March 2018 and June 2018, the Compensation Committee of our Board determined that certain performance milestones were met, and management believes the last performance condition is also probable of being achieved. Stock-based compensation expense associated with these performance-based stock options is recognized over the service and performance period if any performance condition is considered probable of achievement using management’s best estimate. For these performance-based awards, the Company recorded ( $18,000 ) of expense (due to forfeited awards) in the three months ended March 31, 2019. The Company recorded $211,000 of expense in the three months ended March 31, 2018. As of March 31, 2019, there was $2,000 of unrecognized compensation expense remaining related to performance-based awards. Restricted Stock From time to time, upon approval by the Board, certain employees, directors and advisors have been granted restricted shares of common stock and restricted stock units. As of March 31, 2019, the Company does not have any outstanding restricted stock awards or restricted stock units. Employee Stock Purchase Plan On March 14, 2019, the Company issued and sold 8,601 shares of its common stock pursuant to the 2014 ESPP at a purchase price of $0.8356 per share. On March 14, 2018, the Company issued and sold 9,565 shares of its common stock pursuant to the 2014 ESPP at a purchase price of $0.9800 per share. 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.

Net (Loss) Income Per Share

Net (Loss) Income Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net (Loss) Income Per Share	Net (Loss) Income Per Share Basic net (loss) income per share is calculated by dividing net (loss) income by the weighted-average shares outstanding during the period, without consideration for common stock equivalents. Diluted net (loss) income per share is calculated by adjusting weighted-average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the diluted net (loss) income per share calculation, stock options, unvested restricted stock, and common stock warrants are considered to be common stock equivalents. Warrants to purchase the Company’s common stock participate in any dividends declared by the Company 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 they have no contractual obligation to share in the losses of the Company. The following common stock equivalents were excluded from the calculation of diluted net (loss) income per share for the periods indicated because including them would have had an anti-dilutive effect or the exercise prices were greater than the average market price of the common shares. Three Months Ended March 31, 2019 2018 Stock options 5,688,562 2,648,004 Unvested restricted stock — — Common stock warrants 9,257,632 17,602,350 14,946,194 20,250,354

Cash, cash equivalents and rest

Cash, cash equivalents and restricted cash	3 Months Ended
	Mar. 31, 2019
Cash and Cash Equivalents [Abstract]
Cash, cash equivalents and restricted cash	Cash, cash equivalents and restricted cash The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same such amounts shown in the condensed consolidated statements of cash flows (in thousands): March 31, December 31, 2019 2018 Cash and cash equivalents 42,437 $ 50,422 Restricted cash 20 20 Total cash, cash equivalents and restricted cash 42,457 50,442 Amounts included in restricted cash represent cash held to collateralize a credit limit with Silicon Valley Bank of $20,000 as of March 31, 2019 and December 31, 2018, respectively.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company leases an approximately 31,100 square foot manufacturing, laboratory, and office facility in Winnipeg, Manitoba, from an affiliate of Leslie L. Dan, a director of the Company, under a five -year renewable lease through September 2020 with a right to renew the lease for one subsequent five -year term. Operating lease cost under this lease, which includes related operating expenses, was $75,000 for the three months ended March 31, 2019. Under ASC 840, rent expense for this lease was $81,000 for the three months ended March 31, 2018. The Company pays fees, under an intellectual property license agreement, to Protoden Technologies, Inc. (“Protoden”), a company owned by Clairmark Investments Ltd. (“Clairmark”), an affiliate of Mr. Dan, under an intellectual property licensing agreement. Pursuant to the agreement, the Company has an exclusive, perpetual, irrevocable and non-royalty bearing license, with the right to sublicense, under certain patents and technology to make, use and sell products that utilize such patents and technology. The annual fee is $100,000 . Upon expiration of the term, the licenses granted to the Company will require no further payments to Protoden. During each of the three-month periods ended March 31, 2019 and 2018, $100,000 was paid to Clairmark under the license agreement.

Operating Leases

Operating Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Operating Leases	Operating Leases On January 1, 2019, the Company adopted ASC 842 using the optional transition method. The Company’s lease portfolio includes: an operating lease for its manufacturing facility in Winnipeg, Manitoba, a short-term property lease for its headquarters in Cambridge, MA and a short-term property lease for office space in Philadelphia, PA. The asset component of the Company’s operating leases is recorded as operating lease right-of-use assets and reported within other assets in the Company's condensed consolidated balance sheets. The short term and long term liability components are recorded in other current liabilities and other liabilities, respectively, in the Company’s condensed consolidated balance sheets. Operating lease cost is recognized on a straight-line basis over the lease term. The components of lease cost for the three months ended March 31, 2019 are as follows (in thousands): Three months ended March 31, 2019 Lease Cost: Operating lease cost (including related operating costs) 75 Short-term lease cost 76 Total lease cost 151 Supplemental Information: Three months ended March 31, 2019 Weighted-average remaining lease term - operating leases (in years) 1.5 Weighted-average discount rate - operating leases 12 % Future minimum lease payments under non-cancelable operating leases under ASC 842 as of March 31, 2019 are as follows (in thousands): Operating lease payments 2019 (1) 116 2020 116 2021 — Total future minimum lease payments 232 Less: amounts representing present value adjustment 21 Operating lease liabilities as of March 31, 2019 211 Less: current portion of operating lease liabilities 136 Operating lease liabilities, net of current portion 75 (1) Amounts are for the remaining nine months ending December 31, 2019 The Company leases a manufacturing facility located in Winnipeg, Manitoba Canada, which consists of an approximately 31,100 square foot manufacturing, laboratory, warehouse and office facility, 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 approximately $12,900 per month. The Company expects to incur approximately $12,500 in related operating expenses per month. Operating lease cost under this lease, including the related operating costs, was $75,000 for the three months ended March 31, 2019. Under ASC 840, rent expense for this lease, including related operating costs, was $81,000 for the three months ended March 31, 2018. The Company leases its current corporate headquarters in Cambridge, Massachusetts under a short-term lease that was renewed as of January 1, 2019. The minimum monthly rent for this office space is approximately $10,000 per month. The Company recorded $27,000 in short-term lease cost for the three months ended March 31, 2019. Under ASC 840, the Company recorded $26,000 in rent expense for the three months ended March 31, 2018 for this lease. The Company leases office space in Philadelphia, PA, where it occupies office space under a short-term lease that extends through August 2019. Currently, the minimum monthly rent under this lease is approximately $10,000 per month. The Company recorded $49,000 in short term lease cost for the month ended March 31, 2019. Under ASC 840, the Company recorded $24,000 in rent expense for the three months ended March 31, 2018 for this lease.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On April 29, 2019, the Company received written notice from Nasdaq that for 10 consecutive business days, from April 12, 2019 to April 26, 2019, the closing bid price of the Company’s common stock was at $1.00 per share or greater and that, as a result, the Company had regained compliance with Nasdaq Listing Rule 5450(a)(1), which requires the Company to maintain the minimum bid price of $1.00 per share. The Company previously had received a notice from Nasdaq on February 19, 2019 indicating its failure to meet the continued listing requirement for minimum bid price for a period of 30 consecutive business days, and was given 180 calendar days to regain compliance.

Significant Accounting Polici_2

Significant Accounting Policies and Recent Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The condensed consolidated financial statements as of March 31, 2019 and December 31, 2018 and for the three months ended March 31, 2019 and 2018 and the related information contained within the notes to the condensed consolidated financial statements are unaudited. The unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting standards applicable to interim financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s consolidated financial position as of March 31, 2019 , its results of operations for the three months ended March 31, 2019 and 2018, its statement of shareholders' equity for the three months ended March 31, 2019 and 2018, and its cash flows for the three months ended March 31, 2019 and 2018. The financial data and the other financial information disclosed in these notes to the condensed consolidated financial statements related to the three -month periods are also unaudited. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any other future annual or interim period. The condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 that was filed with the Securities and Exchange Commission (“SEC”) on March 1, 2019 (the "2018 Form 10-K"). The condensed consolidated financial statements include the accounts of the Company, its wholly owned subsidiary, Viventia Bio Inc. ("Viventia"), and its indirect subsidiaries, Viventia Bio USA Inc. and Viventia Biotech (EU) Limited. All inter-company transactions and balances have been eliminated in consolidation. The condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles. The functional currency of Viventia, Viventia Bio USA Inc. and Viventia Biotech (EU) Limited is the U.S. dollar.
Recently adopted accounting standards and Recently issued accounting standards	Recently adopted accounting standards In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). ASU 2016-02 addresses the financial reporting of leasing transactions. Under past guidance for lessees, leases are only included on the balance sheet if certain criteria, classifying the agreement as a capital lease, are met. This update requires the recognition of a right-of-use asset and a corresponding lease liability, discounted to the present value, for all leases that extend beyond 12 months. For operating leases, the asset and liability are expensed over the lease term on a straight-line basis, with all cash flows included in the operating section of the statement of cash flows. For finance leases, interest on the lease liability is recognized separately from the amortization of the right-of-use asset in the statement of operations and the repayment of the principal portion of the lease liability is classified as a financing activity while the interest component is included in the operating section of the statement of cash flows. This guidance is effective for annual and interim reporting periods beginning after December 15, 2018 including interim periods within those fiscal years. In July 2018, the FASB issued ASU No. 2018-10, Leases (Topic 842), Codification Improvements (“ASU 2018-10”), ASU No. 2018-11, Leases (Topic 842), Targeted Improvements (“ASU 2018-11”) , and ASU No. 2019-01 Leases (Topic 842), Codification Improvements to provide additional guidance for the adoption Accounting Standards Codification (“ASC”) of Topic 842, Leases (“ASC 842”) . ASU 2018-10 clarifies certain provisions and corrects unintended applications of the guidance, such as the rate implicit in a lease, impairment of the net investment in a lease, lessee reassessment of lease classifications, lessor reassessment of lease term and purchase options, variable payments that depend on an index or rate and certain transition adjustments. The amendments in ASU 2018-11 allow for an additional transition method, whereby at the adoption date the entity recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption, while the comparative period disclosures continue recognition under ASC 840, Leases (“ASC 840”). Additionally, ASU 2018-11 includes a practical expedient for separating contract components for lessors . The Company adopted ASC 842 using the optional transition method outlined in ASU 2018-11 as of January 1, 2019. The adoption of ASC 842 resulted in the recognition of operating lease right-of-use assets of approximately $236,000 and corresponding lease liabilities of approximately $236,000 . The adoption of these ASUs did not have a material impact on the Company’s financial condition or results of operations, however, the adoption resulted in significant changes to the Company’s financial statement disclosures. In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairmen t ("ASU 2017-04"). ASU 2017-04 simplifies the accounting for goodwill impairment by removing Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. ASU 2017-04 is effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019, and should be applied on a prospective basis. The Company adopted this guidance effective January 1, 2019. We do not expect an impact upon adoption of ASU 2017-04 on our condensed consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718) (“Topic 718”): Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). ASU 2018-07 expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees, and as a result, the accounting for share-based payments to non-employees will be substantially aligned. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company adopted this standard effective during the three months ended March 31, 2019. The adoption of ASU 2018-07 did not have a material impact on the Company’s financial position or results of operations. In July 2018, the FASB issued ASU No. 2018-09, “Codification Improvements” (“ASU 2018-09”). ASU 2018-09 provides amendments to a wide variety of topics in the FASB’s Accounting Standards Codification, which applies to all reporting entities within the scope of the affected accounting guidance. The transition and effective date guidance are based on the facts and circumstances of each amendment. Some of the amendments in ASU 2018-09 do not require transition guidance and were effective upon issuance of ASU 2018-09. However, many of the amendments do have transition guidance with effective dates for annual periods beginning after December 15, 2018. ASU 2018-09 did not have a material impact on the Company’s financial statements and related disclosures. Recently issued accounting pronouncements In August 2018, the FASB issued ASU 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. The effective date for ASU 2018-13 is for annual and interim periods beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the impact ASU 2018-13 will have on its consolidated financial statements. In August 2018, the FASB issued ASU 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 Company is currently evaluating the impact ASU 2018-15 will have on its consolidated financial statements. In June 2016, the FASB issued ASU 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 interim and annual reporting periods beginning January 1, 2020, and is to be applied using a modified retrospective transition method. Earlier adoption is permitted. The Company is currently evaluating the impact ASU 2016-13 will have on its consolidated financial statements. Critical accounting policies The Company’s significant accounting policies are described in Note 2, Significant Accounting Policies , in the 2018 Annual Report on Form 10-K. During the three months ended March 31, 2019, the Company adopted the following additional significant accounting policies: Leases Effective January 1, 2019, the Company adopted ASC 842 using the optional transition method. The adoption of ASC 842 represents a change in accounting principle that aims to increase transparency and comparability among organizations by requiring the recognition of right-of-use assets and lease liabilities on the balance sheet for both operating and finance leases. In addition, the standard requires enhanced disclosures that meet the objective of enabling financial statement users to assess the amount, timing, and uncertainty of cash flows arising from leases. The reported results for the three months ended March 31, 2019 reflect the application of ASC 842 guidance, while the reported results for prior periods were prepared in conjunction with ASC 840. As part of the ASC 842 adoption, the Company utilized certain practical expedients outlined in the guidance. These practical expedients include: • Accounting policy election to use the short-term lease exception by asset class; • Election of the practical expedient package during transition, which includes: ◦ An entity need not reassess whether any expired or existing contracts are or contain leases. ◦ An entity need not reassess the classification for any expired or existing leases. As a result, all leases that were classified as operating leases in accordance with ASC 840 are classified as operating leases under ASC 842, and all leases that were classified as capital leases in accordance with ASC 840 are classified as finance leases under ASC 842. ◦ An entity need not reassess initial direct costs for any existing leases. ◦ An entity need not separate out non-lease components from lease components, for all classes of underlying assets The Company’s lease portfolio as of the adoption date includes: a property lease for its manufacturing facility, a property lease for its headquarters in Cambridge, MA, and a property lease for office space in Philadelphia, PA. The Company determines if an arrangement is a lease at the inception of the contract. The asset components of the Company’s operating leases are recorded as operating lease right-of-use assets and reported within Other assets in the Company's condensed consolidated balance sheets. The short term and long term liability components are recorded in Other current liabilities and Other liabilities, respectively, in the Company’s condensed consolidated balance sheets. As of March 31, 2019, the Company did not have any finance leases. Right-of-use assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term at the commencement date. Existing leases in the Company’s lease portfolio as of the adoption date were valued as of January 1, 2019. The Company uses an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments, if an implicit rate of return is not provided with the lease contract. Operating lease right-of-use assets are adjusted for incentives received. Operating lease costs are recognized on a straight-line basis over the lease term, in accordance with ASC 842, and also includes variable operating costs incurred during the period. Lease costs also include amounts related to short term leases.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table summarizes the assets and liabilities measured at fair value on a recurring basis at March 31, 2019 (in thousands): Description March 31, Active Markets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets: Cash and cash equivalents $ 42,437 $ 42,437 $ — $ — Restricted cash 20 20 — — Total assets $ 42,457 $ 42,457 $ — $ — Liabilities: Contingent consideration 47,400 — — 47,400 Total liabilities $ 47,400 $ — $ — $ 47,400 The following table summarizes the assets and liabilities measured at fair value on a recurring basis at December 31, 2018 (in thousands): Description December 31, 2018 Active Markets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets: Cash and cash equivalents $ 50,422 $ 50,422 $ — $ — Restricted cash 20 20 — — Total assets $ 50,442 $ 50,442 $ — $ — Liabilities: Contingent consideration 48,400 — — 48,400 Total liabilities $ 48,400 $ — $ — $ 48,400
Summary of Contingent Consideration Obligations	The following table sets forth a summary of changes in the fair value of the Company's contingent consideration liability (in thousands): Beginning balance, December 31, 2018 $ 48,400 Gain from change in fair value of contingent consideration (1,000 ) Ending balance, March 31, 2019 $ 47,400

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2019
Payables and Accruals [Abstract]
Components of Accrued Expenses	Accrued expenses consisted of the following (in thousands): March 31, December 31, 2018 Development costs $ 3,542 $ 2,928 Employee compensation 491 1,045 Severance to former CEO and other employees 610 278 Professional fees 519 464 Other 72 31 $ 5,234 $ 4,746

Shareholder Equity (Tables)

Shareholder Equity (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Summary of Stock-Based Compensation Expense	Stock-based compensation expense by award type was as follows (in thousands): Three Months Ended 2019 2018 Stock options $ 325 $ 375 Restricted stock — 23 Employee stock purchase plan 1 3 $ 326 $ 401 The Company allocated stock-based compensation expense as follows in the condensed consolidated statements of operations and comprehensive loss (in thousands): Three Months Ended 2019 2018 Research and development expense $ 52 $ 165 General and administrative expense 274 236 $ 326 $ 401
Summary of Stock Option Activity and Related Information	A summary of the stock option activity is presented below: Shares Weighted-Average Exercise Price Outstanding at December 31, 2018 3,941,947 $ 2.12 Granted 2,110,115 0.85 Exercised — — Cancelled or forfeited (363,500 ) 2.44 Outstanding at March 31, 2019 5,688,562 $ 1.62 Exercisable at March 31, 2019 1,076,840 $ 3.13

Net (Loss) Income Per Share (Ta

Net (Loss) Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities	The following common stock equivalents were excluded from the calculation of diluted net (loss) income per share for the periods indicated because including them would have had an anti-dilutive effect or the exercise prices were greater than the average market price of the common shares. Three Months Ended March 31, 2019 2018 Stock options 5,688,562 2,648,004 Unvested restricted stock — — Common stock warrants 9,257,632 17,602,350 14,946,194 20,250,354

Cash, cash equivalents and re_2

Cash, cash equivalents and restricted cash (Tables)	3 Months Ended
	Mar. 31, 2019
Cash and Cash Equivalents [Abstract]
Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same such amounts shown in the condensed consolidated statements of cash flows (in thousands): March 31, December 31, 2019 2018 Cash and cash equivalents 42,437 $ 50,422 Restricted cash 20 20 Total cash, cash equivalents and restricted cash 42,457 50,442

Operating Leases (Tables)

Operating Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lease Cost	The components of lease cost for the three months ended March 31, 2019 are as follows (in thousands): Three months ended March 31, 2019 Lease Cost: Operating lease cost (including related operating costs) 75 Short-term lease cost 76 Total lease cost 151 Supplemental Information: Three months ended March 31, 2019 Weighted-average remaining lease term - operating leases (in years) 1.5 Weighted-average discount rate - operating leases 12 %
Minimum Aggregate Future Lease Commitment	Future minimum lease payments under non-cancelable operating leases under ASC 842 as of March 31, 2019 are as follows (in thousands): Operating lease payments 2019 (1) 116 2020 116 2021 — Total future minimum lease payments 232 Less: amounts representing present value adjustment 21 Operating lease liabilities as of March 31, 2019 211 Less: current portion of operating lease liabilities 136 Operating lease liabilities, net of current portion 75 (1) Amounts are for the remaining nine months ending December 31, 2019

Organization and Basis of Pre_2

Organization and Basis of Presentation (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 42,437	$ 50,422
Net working capital	38,400
Accumulated deficit	$ 192,504	$ 186,024

Significant Accounting Polici_3

Significant Accounting Policies and Recent Accounting Pronouncements - Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liability	$ 211
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset		$ 236
Operating lease liability		$ 236

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Restricted cash	$ 20	$ 20
Liabilities:
Contingent consideration	47,400	48,400
Unobservable Inputs (Level 3)
Liabilities:
Contingent consideration	47,400	48,400
Recurring
Assets:
Cash and cash equivalents	42,437	50,422
Restricted cash	20	20
Total assets	42,457	50,442
Liabilities:
Contingent consideration	47,400	48,400
Total liabilities	47,400	48,400
Recurring | Active Markets (Level 1)
Assets:
Cash and cash equivalents	42,437	50,422
Restricted cash	20	20
Total assets	42,457	50,442
Liabilities:
Contingent consideration	0	0
Total liabilities	0	0
Recurring | Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Total assets	0	0
Liabilities:
Contingent consideration	0	0
Total liabilities	0	0
Recurring | Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Total assets	0	0
Liabilities:
Contingent consideration	47,400	48,400
Total liabilities	$ 47,400	$ 48,400

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Contingent Consideration (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance, December 31, 2018	$ 47,400	$ 48,400
Ending balance, March 31, 2019	47,400
Unobservable Inputs (Level 3)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance, December 31, 2018	47,400	$ 48,400
Gain from change in fair value of contingent consideration	(1,000)
Ending balance, March 31, 2019	$ 47,400

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Additional Information (Details) - Discount Rate	Mar. 31, 2019	Dec. 31, 2018
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate (in percentage)	0.062	0.066
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount rate (in percentage)	0.117	0.137

License Agreement with Roche (D

License Agreement with Roche (Details) - USD ($)	Jan. 01, 2018	Jun. 10, 2016	Mar. 31, 2019	Dec. 31, 2016
Organization And Basis Of Presentation [Line Items]
Adjustments to transaction price			$ 0
Revenue recognized			$ 0
Roche
Organization And Basis Of Presentation [Line Items]
Up-front license fee				$ 7,500,000
Additional up-front fee		$ 240,000,000
Roche | Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
Amount payable upon achievement of specified milestones		50,000,000
Roche | First Indication
Organization And Basis Of Presentation [Line Items]
Amount payable upon achievement of specified milestones		175,000,000
Roche | Collaborative Arrangement, Revenue Based on Regulatory Milestone
Organization And Basis Of Presentation [Line Items]
Amount payable upon achievement of specified milestones		50,000,000
Roche | Collaborative Arrangement, Revenue Based on Commercialization Milestone
Organization And Basis Of Presentation [Line Items]
Amount payable upon achievement of specified milestones		75,000,000
Roche | Second Indication
Organization And Basis Of Presentation [Line Items]
Amount payable upon achievement of specified milestones		$ 65,000,000
Roche | EBI-031 | Minimum
Organization And Basis Of Presentation [Line Items]
Royalty rate		7.50%
Roche | EBI-031 | Maximum
Organization And Basis Of Presentation [Line Items]
Royalty rate		15.00%
Roche | EBI-031 | Collaborative Arrangement, Revenue Based on Development Milestone
Organization And Basis Of Presentation [Line Items]
Amount payable upon achievement of specified milestones				$ 22,500,000
Roche | IL-6
Organization And Basis Of Presentation [Line Items]
Royalty rate		50.00%
Roche
Organization And Basis Of Presentation [Line Items]
Revenue recognized, transaction price	$ 30,000,000

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($)	Sep. 28, 2018	Mar. 31, 2019	Dec. 31, 2018
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Development costs		$ 3,542,000	$ 2,928,000
Employee compensation		491,000	1,045,000
Severance to former CEO and other employees		610,000	278,000
Professional fees		519,000	464,000
Other		72,000	31,000
Total accrued expenses		5,234,000	$ 4,746,000
Former President and Chief Executive Officer
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Severance to former CEO and other employees	$ 637,500	$ 158,000
Base salary	425,000
Bonuses	$ 212,500
Separation Agreement, health and dental insurance coverage period (up to)	12 months

Shareholder Equity - Equity Fin

Shareholder Equity - Equity Financing (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 14, 2019	Jan. 01, 2019	Mar. 14, 2018	Mar. 31, 2018	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from sale of stock				$ 9
Sale of stock, shares issued (in shares)				7,968,128
Stock price per share (in usd per share)				$ 1.13
Number of warrants sold				420,778
Warrant price per unit (in usd per unit)				$ 0.125
Exercise price per warrant (in usd per share)				$ 1.20
Expiration period				5 years
Proceeds from warrant exercises				$ 0.3
2014 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares reserved for future issuance (in shares)		1,102,362
Shares available for issuance (in shares)					1,319,184
2014 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock pursuant to the ESPP (in shares)	8,601		9,565
Common Stock Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of warrants sold				7,968,128

Shareholder Equity - Share-Base

Shareholder Equity - Share-Based Payments (Details) - shares	1 Months Ended			3 Months Ended
	Dec. 31, 2018	Aug. 31, 2018	Sep. 30, 2016	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option to purchase shares (in shares)	425,000		650,000	2,110,115
Outstanding classified as inducement awards (in shares)	3,941,947			5,688,562
Inducement awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding classified as inducement awards (in shares)				1,937,500
Chief Executive Officer | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option to purchase shares (in shares)		1,350,000

Shareholder Equity - Stock-Base

Shareholder Equity - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 326	$ 401
Unrecognized compensation expense	2
2014 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 3,400
Period for recognition	3 years 3 months 29 days
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 52	165
General and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	274	236
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	325	375
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	0	23
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1	$ 3

Shareholder Equity - Summary of

Shareholder Equity - Summary of Stock Option Activity (Details) - $ / shares	1 Months Ended		3 Months Ended
	Dec. 31, 2018	Sep. 30, 2016	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period (in shares)			3,941,947
Granted (in shares)	425,000	650,000	2,110,115
Exercised (in shares)			0
Cancelled or forfeited (in shares)			(363,500)
Outstanding at end of period (in shares)	3,941,947		5,688,562
Exercisable at end of period (in shares)			1,076,840
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period (in USD per share)			$ 2.12
Granted (in USD per share)			0.85
Exercised (in USD per share)			0
Cancelled or forfeited (in USD per share)			2.44
Outstanding at end of period (in USD per share)	$ 2.12		1.62
Exercisable at end of period (in USD per share)			$ 3.13

Shareholder Equity - Stock Opti

Shareholder Equity - Stock Options and Employee Stock Purchase Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 14, 2019	Mar. 14, 2018	Mar. 31, 2019	Mar. 31, 2018
Equity [Abstract]
Compensation expense related to vested awards			$ 18	$ 211
Unrecognized compensation expense			2
2014 ESPP
Equity [Abstract]
Unrecognized compensation expense			$ 3,400
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan issued during period (in shares)	8,601	9,565
Purchase price of shares authorized (in USD per share)	$ 0.8356	$ 0.9800

Net (Loss) Income Per Share -

Net (Loss) Income Per Share - Antidilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
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)	14,946,194	20,250,354
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)	5,688,562	2,648,004
Unvested restricted stock
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)	0	0
Common stock 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)	9,257,632	17,602,350

Cash, cash equivalents and re_3

Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 42,437	$ 50,422
Restricted cash	20	20
Total cash, cash equivalents and restricted cash	$ 42,457	$ 50,442	$ 19,698	$ 14,690

Related Party Transactions (Det

Related Party Transactions (Details) - Director affiliate	3 Months Ended
	Mar. 31, 2019USD ($)ft²option	Mar. 31, 2018USD ($)
Protoden Intellectual Property
Related Party Transaction [Line Items]
Operating lease costs and rent expense in related party transaction	$ 100,000	$ 100,000
Annual fee under license agreement	$ 100,000
Lease Facility In Winnipeg, Manitoba
Related Party Transaction [Line Items]
Office space, square foot | ft²	31,100
Lease term	5 years
Renewal option | option	1
Lease renewal term	5 years
Operating lease costs and rent expense in related party transaction	$ 75,000	$ 81,000

Operating Leases - Lease Costs

Operating Leases - Lease Costs (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Lease Cost:
Operating lease cost (including related operating costs)	$ 75
Short-term lease cost	76
Total lease cost	$ 151
Supplemental Information:
Weighted-average remaining lease term - operating leases (in years)	1 year 6 months
Weighted-average discount rate - operating leases	12.00%

Operating Leases - Narrative (D

Operating Leases - Narrative (Details)	3 Months Ended
	Mar. 31, 2019USD ($)ft²term	Mar. 31, 2018USD ($)
Lessee, Lease, Description [Line Items]
Monthly rent	$ 38,202,000	$ 0
Operating lease cost (including related operating costs)	75,000
Short-term lease cost	$ 76,000
Canada
Lessee, Lease, Description [Line Items]
Office space, square foot | ft²	31,100
Lease term	5 years
Renewal option | term	1
Renewal term	5 years
Monthly rent	$ 12,900
Related operating expenses	12,500
Operating lease cost (including related operating costs)	75,000
Rent expense Under ASC 840		81,000
Massachusetts
Lessee, Lease, Description [Line Items]
Rent expense Under ASC 840		26,000
Short-term lease minimum monthly rent	10,000
Short-term lease cost	27,000
Pennsylvania
Lessee, Lease, Description [Line Items]
Rent expense Under ASC 840		$ 24,000
Short-term lease minimum monthly rent	10,000
Short-term lease cost	$ 49,000

Operating Leases - Minimum Aggr

Operating Leases - Minimum Aggregate Future Lease Commitments (Details) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
2019	$ 116
2020	116
2021	0
Total future minimum lease payments	232
Less: amounts representing present value adjustment	21
Operating lease liabilities as of March 31, 2019	211
Less: current portion of operating lease liabilities	136
Operating lease liabilities, net of current portion	$ 75