0001117480-20-000032 | 10-Q | XBRL Viewer

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Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2020	Oct. 31, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-35867
Entity Registrant Name	CHIMERIX, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0903395
Entity Address, Address Line One	2505 Meridian Parkway
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Durham
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27713
City Area Code	919
Local Phone Number	806-1074
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	CMRX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		62,633,889
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001117480
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 38,130	$ 16,901
Short-term investments, available-for-sale	49,635	96,574
Accounts receivable	378	1,233
Prepaid expenses and other current assets	2,100	3,385
Total current assets	90,243	118,093
Property and equipment, net of accumulated depreciation	291	540
Operating lease right-of-use assets	2,943	709
Other long-term assets	27	34
Total assets	93,504	119,376
Current liabilities:
Accounts payable	880	2,398
Accrued liabilities	6,532	6,830
Total current liabilities	7,412	9,228
Lease-related obligations	2,923	196
Total liabilities	10,335	9,424
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000,000 shares authorized at September 30, 2020 and December 31, 2019; no shares issued and outstanding as of September 30, 2020 and December 31, 2019	0	0
Common stock, $0.001 par value, 200,000,000 shares authorized at September 30, 2020 and December 31, 2019; 62,629,722 and 61,590,013 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	63	62
Additional paid-in capital	783,758	778,693
Accumulated other comprehensive gain, net	33	35
Accumulated deficit	(700,685)	(668,838)
Total stockholders’ equity	83,169	109,952
Total liabilities and stockholders’ equity	$ 93,504	$ 119,376

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
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)	62,629,722	61,590,013
Common stock, shares outstanding (in shares)	62,629,722	61,590,013

Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total revenues	$ 1,609	$ 1,958	$ 4,252	$ 5,752
Operating expenses:
Research and development	10,018	7,453	27,545	34,795
General and administrative	3,151	4,024	9,466	18,022
Acquired in-process research and development	0	65,045	0	65,045
Total operating expenses	13,169	76,522	37,011	117,862
Loss from operations	(11,560)	(74,564)	(32,759)	(112,110)
Other income:
Interest income and other, net	149	834	912	3,037
Net loss	(11,411)	(73,730)	(31,847)	(109,073)
Other comprehensive loss:
Unrealized (loss)/gain on debt investments, net	(97)	(36)	(2)	182
Comprehensive loss	$ (11,508)	$ (73,766)	$ (31,849)	$ (108,891)
Per share information:
Net loss, basic and diluted (in dollars per share)	$ (0.18)	$ (1.26)	$ (0.51)	$ (2.04)
Weighted-average shares outstanding, basic and diluted (in shares)	62,242,456	58,457,110	62,009,941	53,519,207
Contract revenue
Total revenues	$ 1,591	$ 1,958	$ 4,158	$ 5,752
Licensing revenue
Total revenues	$ 18	$ 0	$ 94	$ 0

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Gain (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2018	$ 177,604	$ 51	$ 733,907	$ (92)	$ (556,262)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	4,073		4,073
Exercise of stock options	13		13
Employee stock purchase plan purchases	170		170
Comprehensive loss:
Unrealized gain (loss) on investments, net	140			140
Net loss	(17,693)				(17,693)
Comprehensive loss	(17,553)
Ending Balance at Mar. 31, 2019	164,307	51	738,163	48	(573,955)
Beginning Balance at Dec. 31, 2018	177,604	51	733,907	(92)	(556,262)
Comprehensive loss:
Unrealized gain (loss) on investments, net	182
Comprehensive loss	(108,891)
Ending Balance at Sep. 30, 2019	111,948	61	777,133	89	(665,335)
Beginning Balance at Mar. 31, 2019	164,307	51	738,163	48	(573,955)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	2,367		2,367
Exercise of stock options	17		17
Comprehensive loss:
Unrealized gain (loss) on investments, net	77			77
Net loss	(17,650)				(17,650)
Comprehensive loss	(17,573)
Ending Balance at Jun. 30, 2019	149,118	51	740,547	125	(591,605)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,529		1,529
Exercise of stock options	13		13
Employee stock purchase plan purchases	154		154
Issuance of common stock, net of issuance costs	34,900	10	34,890
Comprehensive loss:
Unrealized gain (loss) on investments, net	(36)			(36)
Net loss	(73,730)				(73,730)
Comprehensive loss	(73,766)
Ending Balance at Sep. 30, 2019	111,948	61	777,133	89	(665,335)
Beginning Balance at Dec. 31, 2019	109,952	62	778,693	35	(668,838)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,326		1,326
Employee stock purchase plan purchases	229		229
Comprehensive loss:
Unrealized gain (loss) on investments, net	(46)			(46)
Net loss	(10,420)				(10,420)
Comprehensive loss	(10,466)
Ending Balance at Mar. 31, 2020	101,041	62	780,248	(11)	(679,258)
Beginning Balance at Dec. 31, 2019	109,952	62	778,693	35	(668,838)
Comprehensive loss:
Unrealized gain (loss) on investments, net	(2)
Comprehensive loss	(31,849)
Ending Balance at Sep. 30, 2020	83,169	63	783,758	33	(700,685)
Beginning Balance at Mar. 31, 2020	101,041	62	780,248	(11)	(679,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,391		1,391
Exercise of stock options	578		578
Comprehensive loss:
Unrealized gain (loss) on investments, net	141			141
Net loss	(10,016)				(10,016)
Comprehensive loss	(9,875)
Ending Balance at Jun. 30, 2020	93,135	62	782,217	130	(689,274)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,282		1,282
Exercise of stock options	63	1	62
Employee stock purchase plan purchases	197		197
Comprehensive loss:
Unrealized gain (loss) on investments, net	(97)			(97)
Net loss	(11,411)				(11,411)
Comprehensive loss	(11,508)
Ending Balance at Sep. 30, 2020	$ 83,169	$ 63	$ 783,758	$ 33	$ (700,685)

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (31,847)	$ (109,073)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	309	451
Amortization of discount/premium on investments	(268)	(1,557)
Share-based compensation	4,000	7,969
Fair value of common stock issued for license agreement	0	34,900
(Gain)/loss on sale of investments	(1)	31
Gain on sale of equipment	(10)	0
Lease-related amortization	(47)	(57)
Changes in operating assets and liabilities:
Accounts receivable	855	(1,492)
Prepaid expenses and other assets	1,284	178
Accounts payable and accrued liabilities	(1,268)	(3,062)
Net cash used in operating activities	(26,993)	(71,712)
Cash flows from investing activities:
Purchases of property and equipment	(60)	(150)
Proceeds from sale of property and equipment	10	0
Purchases of short-term investments	(58,895)	(130,351)
Proceeds from sales of short-term investments	1,498	13,112
Proceeds from maturities of short-term investments	104,602	127,000
Net cash provided by investing activities	47,155	9,611
Cash flows from financing activities:
Proceeds from exercise of stock options	641	43
Proceeds from employee stock purchase plan	426	324
Payments of deferred offering costs	0	(23)
Net cash provided by financing activities	1,067	344
Net increase (decrease) in cash and cash equivalents	21,229	(61,757)
Cash and cash equivalents:
Beginning of period	16,901	81,106
End of period	$ 38,130	$ 19,349

The Business and Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2020

Accounting Policies [Abstract]

The Business and Summary of Significant Accounting Policies

Description of Business

Chimerix, Inc. (the Company) is a development-stage biopharmaceutical company dedicated to accelerating the advancement of innovative medicines that make a meaningful impact in the lives of patients living with cancer and other serious diseases. The Company has two clinical-stage product candidates, dociparstat sodium (DSTAT) and brincidofovir (BCV). DSTAT is a heparin derivative with significantly decreased anticoagulant activity; this enables dosing at higher concentrations to achieve anti-inflammatory and other potentially beneficial effects that cannot be safely achieved with commercially available forms of heparin. DSTAT is in development as a potential first-line therapy in acute myeloid leukemia (AML) and as a potential treatment for acute lung injury (ALI) in COVID-19 patients. BCV is an investigational lipid conjugate that is in development as a medical countermeasure for smallpox. The Company expects to continue its evaluation of external innovation in order to license, acquire or otherwise gain access to molecules that further broaden its pipeline of investigational agents in cancer or other serious diseases.

Basis of Presentation

The accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the Company’s audited financial statements and notes thereto included in its Annual Report on Form 10-K for the year ended December 31, 2019. In the opinion of the Company’s management, all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of its financial position, operating results and cash flows for the periods presented have been included. Operating results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results that may be expected for the full year, for any other interim period or for any future year.

Reclassifications

Certain prior period amounts in the accompanying consolidated financial statements have been reclassified to conform to the current year presentation. These reclassifications had no effect on previously reported net income or stockholders' equity (deficit).

Fair Value of Financial Instruments

The carrying amounts of certain financial instruments, including accounts receivable, accounts payable and accrued expenses approximate their fair values due to the short-term nature of such instruments.

For assets and liabilities recorded at fair value, it is the Company’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements, in accordance with the fair value hierarchy. Fair value measurements for assets and liabilities where there exists limited or no observable market data are based primarily upon estimates and are often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, fair value measurements cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the calculated current or future fair values. The Company utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures.

The Company groups assets and liabilities at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The determination of where an asset or liability falls in the hierarchy requires significant judgment. These levels are:

•Level 1 — Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access.

•Level 2 — Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical

or similar assets or liabilities in markets that are not active, and models for which all significant inputs are observable, either directly or indirectly.

•Level 3 — Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

At September 30, 2020 and December 31, 2019, the Company had cash equivalents including money market funds, whose value is based on quoted market prices. At September 30, 2020 and December 31, 2019, the Company had short term investments, including U.S. Treasury securities, whose value is based on quoted market prices. Accordingly, these securities are classified as Level 1.

At September 30, 2020 and December 31, 2019, the Company had short-term investments, including commercial paper and corporate bonds. As quoted prices are not available for these securities, they are valued using independent pricing models or other model-based valuation techniques such as the present value of future cash flows, adjusted for the security’s credit rating, prepayment assumptions and other factors such as credit loss assumptions. Accordingly, these securities are classified as Level 2.

There was no material re-measurement to fair value of financial assets and liabilities that are not measured at fair value on a recurring basis. For additional information regarding the Company's investments, please refer to Note 2, "Investments."

Below are tables that present information about certain assets measured at fair value on a recurring basis (in thousands):


	Fair Value Measurements
	September 30, 2020
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	34,816	$	34,816	$	—	$	—




Total cash equivalents	34,816		34,816		—		—
Short-term investments

U.S. treasury securities	34,227		34,227		—		—

Commercial paper	3,999		—		3,999		—
Corporate bonds	11,409		—		11,409		—
Total short-term investments	49,635		34,227		15,408		—




Total assets	$	84,451	$	69,043	$	15,408	$	—

	Fair Value Measurements
	December 31, 2019
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	11,854	$	11,854	$	—	$	—



Total cash equivalents	11,854		11,854		—		—
Short-term investments

U.S. treasury securities	22,493		22,493		—		—

Commercial paper	43,119		—		43,119		—
Corporate bonds	30,962		—		30,962		—
Total short-term investments	96,574		22,493		74,081		—





Total assets	$	108,428	$	34,347	$	74,081	$	—

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):


	September 30, 2020		December 31, 2019
Accrued research and development expenses	$	3,034	$	1,868
Accrued compensation	2,752		3,626
Other accrued liabilities	746		1,336

Total accrued liabilities	$	6,532	$	6,830

Revenue Recognition

Policy

The Company’s revenues generally consist of (i) contract revenue - revenue generated under federal contracts, and (ii) collaboration and licensing revenue - revenue related to non-refundable upfront fees, royalties and milestone payments earned under license agreements. Revenue is recognized in accordance with the criteria outlined in Accounting Standards Codification (ASC) 606 issued by the Financial Accounting Standards Board (FASB). Following this accounting pronouncement, a five-step approach is applied for recognizing revenue, including (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation.

Biomedical Advanced Research and Development Authority (BARDA)

In February 2011, the Company entered into a contract with BARDA for the advanced development of BCV as a medical countermeasure in the event of a smallpox release. Under the contract, the Company may receive up to $75.8 million in expense reimbursement and $5.3 million in fees over the performance of 1 base segment and 4 option segments. Exercise of each option segment is solely at the discretion of BARDA. The Company assessed the services in accordance with the authoritative guidance and concluded that there is a potential of 5 separate contracts (1 base segment and 4 option segments) within this agreement, each of which has a single performance obligation. At present, all option segments (1 through 4) have been exercised, as well as the base segment. The transaction price for each segment, based on the transaction price as defined in each segment contract, is allocated to the single performance obligation for each contract. The transaction price is recognized over time by measuring the progress toward complete satisfaction of the performance obligation. For reimbursable expenses, this occurs as qualifying research activities are conducted based on invoices from company vendors. For the fixed fee, the progress toward complete satisfaction is estimated based on the costs incurred to date relative to the total estimated costs per the terms of each contract. The Company typically invoices BARDA monthly as costs are incurred. Any amounts received in advance of performance are recorded as deferred revenue until earned. The base segment and first option segment were completed prior to adoption of ASC 606. The Company is currently performing under the fourth option segment of the contract during which the Company may receive up to a total of $4.6 million in expense reimbursement and fees. The second and third option segments were completed on August 20, 2020. The fourth option segment is scheduled to end on February 15, 2021.

SymBio Pharmaceuticals

On September 30, 2019, the Company entered into a license agreement with SymBio Pharmaceuticals Limited (SymBio) under which the Company granted SymBio exclusive worldwide rights to develop, manufacture and commercialize BCV for all human indications, excluding the prevention and treatment of orthopoxviruses, including smallpox. The Company assessed the agreement in accordance with the authoritative guidance and concluded that the SymBio contract includes multiple performance obligations. The SymBio contract has one fixed transaction amount of a $5.0 million upfront payment received in October 2019 and several variable transaction amounts, up to $180 million, due to the Company at certain regulatory and commercial milestones, along with low double-digit percent royalties based on net sales of BCV. All variable transaction amounts are fully constrained, therefore the allocated transaction price is $5.0 million. The majority of the transaction price of the contract has been allocated to the combined performance obligation of the granting of the license to BCV and associated technology transfer which was recognized when the technology transfer was completed in the fourth quarter of 2019. The revenue from regulatory and commercial milestones and royalties from net sales will be recognized upon the occurrence of the triggering events or when those transaction amounts are no longer fully constrained.

Research and Development Prepaids and Accruals

As part of the process of preparing financial statements, the Company is required to estimate its expenses resulting from its

obligation under contracts with vendors and consultants and clinical site agreements in connection with its research and development efforts. The financial terms of these contracts are subject to negotiations which vary contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts.

The Company’s objective is to reflect the appropriate research and development expenses in its financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of its research and development efforts. The Company determines prepaid and accrual estimates through discussion with applicable personnel and outside service providers as to the progress or state of communication of clinical trials, or other services completed. The Company adjusts its rate of research and development expense recognition if actual results differ from its estimates. The Company makes estimates of its prepaid and accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through September 30, 2020, there had been no material adjustments to the Company’s prior period estimates of prepaid and accruals for research and development expenses. The Company’s research and development prepaids and accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors.

Basic and Diluted Net Loss Per Share of Common Stock

Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the period, excluding the dilutive effects of non-vested restricted stock, stock options, and employee stock purchase plan purchase rights. Diluted net loss per share of common stock is computed by dividing net loss by the sum of the weighted-average number of shares of common stock outstanding during the period plus the potential dilutive effects of non-vested restricted stock, stock options, and employee stock purchase plan purchase rights outstanding during the period calculated in accordance with the treasury stock method, but are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during the periods of net loss, there was no difference between basic and diluted loss per share of common stock for the three and nine months ended September 30, 2020 and 2019.

Impact of Recently Issued Accounting Standards

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach on expected losses to estimate credit losses on certain financial instruments, including trade receivables and available-for-sale debt securities. The new guidance was originally due to become effective for the Company beginning in the first quarter of 2020, however the FASB in November 2019 issued ASU 2019-10 which moved the effective date for smaller reporting companies to the first quarter of 2023. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements.

Investments

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Investments

The following tables summarize the Company's debt investments (in thousands):


	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Corporate bonds	$	11,381	$	28	$	—	$	11,409

U.S. treasury securities	34,230		2		(5)		34,227
Commercial paper	3,990		9		—		3,999

Total investments	$	49,601	$	39	$	(5)	$	49,635

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Corporate bonds	$	30,952	$	19	$	(9)	$	30,962
Commercial paper	43,109		14		(4)		43,119

U.S. treasury securities	22,478		17		(2)		22,493

Total investments	$	96,539	$	50	$	(15)	$	96,574

The following tables summarize the Company's debt investments with unrealized losses, aggregated by investment type and the length of time that individual investments have been in a continuous unrealized loss position (in thousands, except number of securities):


	September 30, 2020
	Less than 12 Months				Greater than 12 Months				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss


U.S. treasury securities	$	25,128	$	(5)	$	—	$	—	$	25,128	$	(5)

Total	$	25,128	$	(5)	$	—	$	—	$	25,128	$	(5)
Number of securities with unrealized losses			8				—				8

	December 31, 2019
	Less than 12 Months				Greater than 12 Months				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss

Corporate bonds	$	9,657	$	(9)	$	—	$	—	$	9,657	$	(9)
Commercial paper	10,147		(4)		—		—		10,147		(4)
U.S. treasury securities	2,994		(2)		—		—		2,994		(2)

Total	$	22,798	$	(15)	$	—	$	—	$	22,798	$	(15)
Number of securities with unrealized losses			9				—				9

The Company periodically reviews available-for-sale debt investments for other-than-temporary declines in fair value below the cost basis and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company evaluates, among other things, the duration and extent to which the fair value of a security is less than its cost; the financial condition of the issuer and any changes thereto; and the Company’s intent to sell, or whether it will more likely than not be required to sell, the security before recovery of its cost basis. At September 30, 2020, the Company did not intend to sell, and was not more likely than not to be required to sell, the available-for-sale debt investments in an unrealized loss position before recovery of the cost basis of the securities, which may be at maturity. There were no such declines in value for the three and nine months ended September 30, 2020 and 2019. Unrealized gains and losses on debt

investments are recorded to unrealized (loss) gain on debt investments, net in the Consolidated Statements of Operations and Comprehensive Loss. The Company recognizes interest income on an accrual basis in interest income in the Consolidated Statements of Operations and Comprehensive Loss.

The following table summarizes the scheduled maturity for the Company's debt investments at September 30, 2020 (in thousands):


Maturing in one year or less	$	49,635
Maturing after one year through two years	—
Total debt investments	$	49,635

Commitments and Contingencies

9 Months Ended

Sep. 30, 2020

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Leases

The Company leases its facilities under long-term operating leases that expire at various dates through 2026. The Company generally has options to renew lease terms on its facilities, which may be exercised at the Company's sole discretion. In addition, certain lease arrangements may be terminated prior to their original expiration date at the Company's discretion. The Company evaluates renewal and termination options at the lease commencement date to determine if it is reasonably certain to exercise the option and has concluded on all operating leases that it is not reasonably certain that any options will be exercised. The weighted-average remaining lease term for the Company's operating leases as of September 30, 2020 was 6.03 years.

Expense related to leases is recorded on a straight-line basis over the lease term. Lease expense under operating leases, including common area maintenance fees, totaled approximately $184,000 and $187,000, respectively, for the three months ended September 30, 2020 and 2019, and $550,000 and $563,000 for the nine months ended September 30, 2020 and 2019, respectively.

The discount rate implicit within the Company's leases is generally not determinable and therefore the Company determines the discount rate based on its incremental borrowing rate based on the information available at commencement date. As of September 30, 2020, the operating lease liabilities reflect a weighted-average discount rate of 7.93%.

The following table sets forth the operating lease right-of-use assets and liabilities as of September 30, 2020 (in thousands):


Assets
Operating lease right-of-use assets	$	2,943

Liabilities
Operating lease short-term liabilities (recorded within Accrued liabilities)	$	91
Operating lease long-term liabilities (recorded within Lease-related obligations)	2,923
Total operating lease liabilities	$	3,014

Operating lease payments over the remainder of the lease terms are as follows (in thousands):


Years Ending December 31,	As of September 30, 2020
2020	$	147
2021 (1)	260
2022	715
2023	736
2024	759
All remaining years	1,248
Total future minimum rental payments	$	3,865
Less amount of lease payments representing interest	851
Total present value of lease payments	$	3,014

(1)The Company entered into the Ninth Amendment of its lease for the Company's headquarters in Durham, North Carolina, which extended the term of the lease 65 months to July 31, 2026. As part of the amendment, the Company will receive a rent abatement of the first 5 months of the new lease term which begins on March 1, 2021. Additionally, the Ninth Amendment grants the Company a refurbishment allowance, which the Company expects to receive in 2021 after the refurbishment has been completed.

As of December 31, 2019, operating lease payments over the remainder of the lease terms were as follows (in thousands):


Years Ending December 31,	As of December 31, 2019

2020	$	719
2021	182


Total future minimum rental payments	$	901
Less amount of lease payments representing interest	66
Total present value of lease payments	$	835

For the three months ended September 30, 2020 and 2019, the Company made lease payments of approximately $181,000 and $188,000, respectively, and for the nine months ended September 30, 2020 and 2019, the Company made lease payments of approximately $538,000 and $574,000, respectively, which are included in operating cash flows.

Sublease

The Company subleases 3,537 square feet of its office space under a non-cancelable operating lease that expires in February 2021. For the three and nine months ended September 30, 2020 and 2019, the Company recognized approximately $18,000 and $53,000 of income in Interest income and other, net on the Consolidated Statement of Operations and Comprehensive Loss. Total future minimum rentals under the non-cancelable operating sublease are presented below (in thousands):


Years Ending December 31,	As of September 30, 2020

2020	$	21
2021	14


Total future minimum sublease rentals	$	35

Significance of Revenue Source

The Company is the recipient of federal research contract funds from BARDA, the sole source of the Company's contract revenue. Periodic audits are required under the Company’s BARDA agreement and certain costs may be questioned as appropriate under the BARDA agreement. Management believes that such amounts in the current year, if any, are not significant. Accordingly, no provision for refundable amounts under the BARDA agreement had been made as of September 30, 2020 and December 31, 2019.

Equity Transactions and Share-based Compensation

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [Abstract]

Equity Transactions and Share-based Compensation

Stock Options

The Company maintains a 2013 Equity Incentive Plan (the 2013 Plan), which provides for the grant of incentive stock options (ISOs), non-statutory stock options (NSOs), stock appreciation rights, restricted stock awards, restricted stock unit (RSU) awards, performance-based stock awards, and other forms of equity compensation (collectively, stock awards), all of which may be granted to employees, including officers, non-employee directors and consultants of the Company and its affiliates. Additionally, the 2013 Plan provides for the grant of performance cash awards. The number of shares of common stock reserved for future issuance automatically increases on January 1 of each calendar year by 4% of the total number of shares of capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by the Company’s board of directors. On January 1, 2020, the common stock reserved for issuance under the 2013 Plan was automatically increased by 2.5 million shares. As of September 30, 2020, there was a total of 3.4 million shares reserved for future issuance under the 2013 Plan. The Company issued approximately 21,000 and 263,000 shares of common stock pursuant to the exercise of stock options during the three and nine months ended September 30, 2020. The Company issued approximately 5,000 and 19,000 shares of common stock pursuant to the exercise of stock options during the three and nine months ended September 30, 2019, respectively.

Employee Stock Purchase Plan

The Company maintains a 2013 Employee Stock Purchase Plan (ESPP), which provides for the issuance of shares of common stock pursuant to purchase rights granted to the Company’s employees or to employees of any of its designated affiliates. The Company has reserved a total of 3.5 million shares of common stock to be purchased under the ESPP, of which 2.4 million shares remained available for purchase as of September 30, 2020. The number of shares of common stock reserved for issuance automatically increases on January 1 of each calendar year, by the lesser of (a) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, (b) 422,535 shares, or (c) a number determined by the Company’s board of directors that is less than (a) and (b). On January 1, 2020, the common stock reserved for issuance under the ESPP was automatically increased by an additional 422,535 shares.

The ESPP provides for an automatic reset feature to start participants on a new twenty-four month participation period in the event that the common stock market value on a purchase date is less than the common stock value on the first day of the twenty-four month offering period. Eligible employees may authorize an amount up to 15% of their salary to purchase common stock at the lower of a 15% discount to the beginning price of their offering period or a 15% discount to the ending price of each six-month purchase interval. The Company issued approximately 160,000 and 96,000 shares of common stock pursuant to the ESPP during the three months ended September 30, 2020 and 2019, respectively. The Company issued approximately 337,000 and 209,000 shares of common stock pursuant to the ESPP during the nine months ended September 30, 2020 and 2019, respectively. Compensation expense for shares purchased under the ESPP related to the purchase discount and the “look-back” option and were determined using a Black-Scholes option pricing model.

Restricted Stock Units

The Company has issued RSUs to certain employees which vest based on service criteria. When vested, the RSU represents the right to be issued the number of shares of the Company's common stock that is equal to the number of RSUs granted. The grant date fair value for RSUs is based upon the market price of the Company's common stock on the date of the grant. The fair value is then amortized to compensation expense over the requisite service period or vesting term. The Company issued approximately 277,000 and 440,000 shares of common stock pursuant to the vesting of RSUs during the three and nine months ended September 30, 2020, respectively. The Company issued approximately 50,000 and 419,000 shares of common stock pursuant to the vesting of RSUs during the three and nine months ended September 30, 2019, respectively.

Stock-based Compensation

For awards with only service conditions and graded-vesting features, the Company recognizes compensation expense on a straight-line basis over the requisite service period. Total share-based compensation expense recognized related to stock options, the ESPP and RSUs was as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development expense	$	625	$	901	$	2,090	$	3,170
General and administrative expense	657		628		1,910		4,799
Total share-based compensation expense	$	1,282	$	1,529	$	4,000	$	7,969

Compensation expense for the nine months ended September 30, 2019 includes $1.8 million of share-based compensation expense related to the accelerated vesting and modification of stock options and RSUs of the Company's then President and CEO in connection with her severance agreement.

Related to the Company's reduction in workforce that occurred in May 2019, compensation expense for the nine months ended September 30, 2019 includes $0.7 million of share-based compensation expense related to the accelerated vesting and modifications of stock options and RSUs.

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company estimates an annual effective tax rate of 0% for the year ending December 31, 2020 as the Company incurred losses for the nine month period ended September 30, 2020, and is forecasting an estimated net loss for both financial statement and tax purposes for the year ending December 31, 2020. Therefore, no federal or state income taxes are expected and none have been recorded at this time. Income taxes have been accounted for using the liability method in accordance with FASB ASC 740. Due to the Company's history of losses since inception, there is not enough evidence at this time to support that the Company will generate future income of a sufficient amount and nature to utilize the benefits of its net deferred tax assets. Accordingly, the deferred tax assets have been reduced by a full valuation allowance, since the Company cannot currently support that realization of its deferred tax assets is more likely than not. However, the Company feels its deferred tax assets may be used upon the Company becoming profitable. At September 30, 2020, the Company had no unrecognized tax benefits that would reduce the Company’s effective tax rate if recognized.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Significant Agreements	9 Months Ended
Significant Agreements	Sep. 30, 2020
Revenue Recognition [Abstract]
Significant Agreements	Significant Agreements Biomedical Advanced Research and Development Authority (BARDA) In February 2011, the Company entered into a contract with BARDA for the advanced development of BCV as a medical countermeasure in the event of a smallpox release. Under the contract, BARDA will reimburse the Company, plus pay a fixed fee, for the research and development of BCV as a broad-spectrum therapeutic antiviral for the treatment of smallpox infections. The contract consists of an initial performance period, referred to as the base performance segment, plus up to four extension periods, referred to as option segments, of which all have been exercised. Under the contract as currently in effect, the Company may receive up to $75.8 million in expense reimbursement and $5.3 million in fees. The Company is currently performing under the fourth option segment of the contract during which the Company may receive up to a total of $4.6 million in expense reimbursement and fees. The second and third option segments were completed on August 20, 2020. The fourth option segment is scheduled to end on February 15, 2021. Of the $75.8 million in expense reimbursement and $5.3 million in fees that the Company may receive, approximately $78.9 million in expense reimbursement and fees has been awarded. As of September 30, 2020, of the total funding the Company had invoiced an aggregate of $74.4 million with respect to the base performance segment and the four option segments. For the three months ended September 30, 2020 and 2019, the Company recognized revenue under this contract of $1.6 million and $2.0 million, respectively, and for the nine months ended September 30, 2020 and 2019, the Company recognized revenue under this contract of $4.2 million and $5.8 million, respectively. Cantex Pharmaceuticals, Inc. On July 26, 2019, the Company entered into a License and Development Agreement with Cantex Pharmaceuticals, Inc. (Cantex) pursuant to which the Company acquired exclusive worldwide rights to develop and commercialize, for any and all uses, a glycosaminoglycan compound known as DSTAT, which is currently being studied for the treatment of acute myeloid leukemia and acute lung injury in patients with COVID-19. Under the terms of the license agreement, the Company will be responsible for, and bear the future costs of, worldwide development and commercialization of DSTAT. In connection with the transaction, Cantex assigned to the Company all of its rights under its DSTAT supply agreements, including its bulk API agreement with Scientific Protein Laboratories LLC (SPL), pursuant to which SPL will exclusively produce DSTAT for the Company through October 2030. In consideration for the license rights, the Company made an upfront cash payment of $30.0 million to Cantex and issued to Cantex 10.0 million shares of its common stock. During 2019, the Company recognized $65.0 million of acquired in-process research and development expenses for the $30.0 million upfront cash payment, the fair value of the 10.0 million shares of common stock issued to Cantex and $0.1 million of transaction costs. The license agreement obligates the Company to pay Cantex regulatory milestone payments of up to $202.5 million upon receipt of product approvals in the United States, the European Union and Japan, and sales milestone payments of up to $385.0 million upon achievement of specified net sales levels. The Company also agreed to pay Cantex tiered royalties based on percentages of net sales beginning at 10% and not to exceed the high-teens. SymBio Pharmaceuticals On September 30, 2019, the Company entered into a license agreement with SymBio under which the Company granted SymBio exclusive worldwide rights to develop, manufacture and commercialize BCV for all human indications, excluding the prevention and treatment of orthopoxviruses, including smallpox. Under the terms of the license agreement, SymBio will be responsible for, and bear the future costs of, worldwide development and commercialization of BCV in the licensed indications. Either party may terminate the license agreement upon the occurrence of a material breach by the other party (subject to standard cure periods). SymBio may also terminate the license agreement without cause on a country-by-country basis upon ninety days' prior notice. In exchange for the license to SymBio under the Company's BCV rights, the Company received an upfront payment of $5.0 million in October 2019. In addition, the Company is eligible to receive up to $180.0 million in clinical, regulatory and commercial milestones worldwide, as well as low double-digit percent royalties based on net sales of BCV. Since entering into the license agreement in September 2019, the Company has recognized all of the $5.0 million upfront payment.

Restructuring Costs

9 Months Ended

Sep. 30, 2020

Restructuring and Related Activities [Abstract]

Restructuring Costs

Restructuring CostsIn May 2019, the Company made the decision to discontinue the development of oral and IV BCV development programs for the treatment of Adenovirus (AdV) in stem-cell transplant (HCT) patients. The Company's development efforts with respect to BCV are now focused on the treatment of smallpox. As a result, the Company restructured its operations, which included a reduction in workforce of 43 full-time employees and the accrual of expenses to close-out the clinical trials for the oral and IV development programs of BCV in AdV (study 210, study 211, AdAPT) and other supportive BCV development programs. In 2019, the Company recorded charges for one-time employee termination benefits of $3.3 million, contract close-out costs of $2.0 million, other BCV development costs of $0.3 million, and losses on disposals of fixed assets of $0.3 million during 2019. The $2.0 million of contract close-out costs were recorded through an increase in liabilities of $1.5 million with the remainder recognized through the expensing of prepaid balances. As of December 31, 2019, the Company had a clinical trial accrual balance related to the AdAPT, 210 and 211 trial terminations of $27,000, other development costs accrual balance of $0.1 million, and severance accrual balance of $0.2 million. Additionally, as of December 31, 2019 prepaid balances of $1.3 million for unused deposits have been reclassed to other receivables, which was recorded in prepaid expenses and other current assets on the Consolidated Balance Sheet.

The following table summarizes the restructuring charges (in thousands) recorded in 2019 during the period subsequent to the restructuring in May 2019:


	Employee Termination Benefits		Clinical Trial Close-out Costs		Other Development Costs		Fixed Asset Disposals		Total
Research and development	$	1,437	$	2,021	$	339	$	—	$	3,797
General and administrative	1,909		—		—		—		1.909
Interest income and other, net	—		—		—		250		250
Total restructuring expenses	$	3,346	$	2,021	$	339	$	250	$	5,956

For the three months ended September 30, 2019, the Company recorded a $156,000 reduction of research and development restructuring charges. For the nine months ended September 30, 2019, $4.4 million of research and development and $1.9 million of general and administrative restructuring charges were recorded.

The following table sets forth the accrual activity for employee termination benefits and contract close-out costs (in thousands) for 2019.


	Employee Termination Benefits		Clinical Trial Close-out Costs		Other Development Costs		Fixed Asset Disposals		Total
Balance at January 1, 2019	$	—	$	—	$	—	$	—	$	—
Accruals	3,335		2,131		315		—		5,781
Revised estimates	11		(621)		24		250		(336)
Payments	(3,163)		(1,483)		(229)		(250)		(5,125)
Balance at December 31, 2019	$	183	$	27	$	110	$	—	$	320

The following table sets forth the accrual activity for employee termination benefits and contract close-out costs (in thousands) for the nine months ended September 30, 2020.


	Employee Termination Benefits		Clinical Trial Close-out Costs		Other Development Costs		Total
Balance at December 31, 2019	$	183	$	27	$	110	$	320

Revised estimates	—		(14)		—		(14)
Payments	(114)		(4)		(100)		(218)
Balance at March 31, 2020	$	69	$	9	$	10	$	88
Revised estimates	—		(5)		—		(5)
Payments	(69)		—		—		(69)
Balance at June 30, 2020	$	—	$	4	$	10	$	14
Revised estimates	—		(4)		(10)		(14)
Payments	—		—		—		—
Balance at September 30, 2020	$	—	$	—	$	—	$	—

For the three and nine months ended September 30, 2020, the revised accrual estimates resulted in a decrease to research and development expenses of $14,000 and $33,000, respectively. Additionally, during the nine months ended September 30, 2020 refunds of unused deposits of $1.3 million were received, which were previously recorded in prepaid expenses and other current assets on the Consolidated Balance Sheet.

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company has evaluated subsequent events through the issuance date of these financial statements to ensure that this filing includes appropriate disclosure of events both recognized in the financial statements as of September 30, 2020, and events which occurred subsequently but were not recognized in the financial statements.

The Business and Summary of Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the Company’s audited financial statements and notes thereto included in its Annual Report on Form 10-K for the year ended December 31, 2019. In the opinion of the Company’s management, all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of its financial position, operating results and cash flows for the periods presented have been included. Operating results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results that may be expected for the full year, for any other interim period or for any future year.
Reclassifications	Reclassifications Certain prior period amounts in the accompanying consolidated financial statements have been reclassified to conform to the current year presentation. These reclassifications had no effect on previously reported net income or stockholders' equity (deficit).
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of certain financial instruments, including accounts receivable, accounts payable and accrued expenses approximate their fair values due to the short-term nature of such instruments. For assets and liabilities recorded at fair value, it is the Company’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements, in accordance with the fair value hierarchy. Fair value measurements for assets and liabilities where there exists limited or no observable market data are based primarily upon estimates and are often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, fair value measurements cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the calculated current or future fair values. The Company utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The Company groups assets and liabilities at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The determination of where an asset or liability falls in the hierarchy requires significant judgment. These levels are: •Level 1 — Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. •Level 2 — Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and models for which all significant inputs are observable, either directly or indirectly. •Level 3 — Valuations based on inputs that are unobservable and significant to the overall fair value measurement. At September 30, 2020 and December 31, 2019, the Company had cash equivalents including money market funds, whose value is based on quoted market prices. At September 30, 2020 and December 31, 2019, the Company had short term investments, including U.S. Treasury securities, whose value is based on quoted market prices. Accordingly, these securities are classified as Level 1. At September 30, 2020 and December 31, 2019, the Company had short-term investments, including commercial paper and corporate bonds. As quoted prices are not available for these securities, they are valued using independent pricing models or other model-based valuation techniques such as the present value of future cash flows, adjusted for the security’s credit rating, prepayment assumptions and other factors such as credit loss assumptions. Accordingly, these securities are classified as Level 2. There was no material re-measurement to fair value of financial assets and liabilities that are not measured at fair value on a recurring basis. For additional information regarding the Company's investments, please refer to Note 2, "Investments."
Revenue Recognition	Revenue Recognition Policy The Company’s revenues generally consist of (i) contract revenue - revenue generated under federal contracts, and (ii) collaboration and licensing revenue - revenue related to non-refundable upfront fees, royalties and milestone payments earned under license agreements. Revenue is recognized in accordance with the criteria outlined in Accounting Standards Codification (ASC) 606 issued by the Financial Accounting Standards Board (FASB). Following this accounting pronouncement, a five-step approach is applied for recognizing revenue, including (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. Biomedical Advanced Research and Development Authority (BARDA) In February 2011, the Company entered into a contract with BARDA for the advanced development of BCV as a medical countermeasure in the event of a smallpox release. Under the contract, the Company may receive up to $75.8 million in expense reimbursement and $5.3 million in fees over the performance of 1 base segment and 4 option segments. Exercise of each option segment is solely at the discretion of BARDA. The Company assessed the services in accordance with the authoritative guidance and concluded that there is a potential of 5 separate contracts (1 base segment and 4 option segments) within this agreement, each of which has a single performance obligation. At present, all option segments (1 through 4) have been exercised, as well as the base segment. The transaction price for each segment, based on the transaction price as defined in each segment contract, is allocated to the single performance obligation for each contract. The transaction price is recognized over time by measuring the progress toward complete satisfaction of the performance obligation. For reimbursable expenses, this occurs as qualifying research activities are conducted based on invoices from company vendors. For the fixed fee, the progress toward complete satisfaction is estimated based on the costs incurred to date relative to the total estimated costs per the terms of each contract. The Company typically invoices BARDA monthly as costs are incurred. Any amounts received in advance of performance are recorded as deferred revenue until earned. The base segment and first option segment were completed prior to adoption of ASC 606. The Company is currently performing under the fourth option segment of the contract during which the Company may receive up to a total of $4.6 million in expense reimbursement and fees. The second and third option segments were completed on August 20, 2020. The fourth option segment is scheduled to end on February 15, 2021. SymBio Pharmaceuticals On September 30, 2019, the Company entered into a license agreement with SymBio Pharmaceuticals Limited (SymBio) under which the Company granted SymBio exclusive worldwide rights to develop, manufacture and commercialize BCV for all human indications, excluding the prevention and treatment of orthopoxviruses, including smallpox. The Company assessed the agreement in accordance with the authoritative guidance and concluded that the SymBio contract includes multiple performance obligations. The SymBio contract has one fixed transaction amount of a $5.0 million upfront payment received in October 2019 and several variable transaction amounts, up to $180 million, due to the Company at certain regulatory and commercial milestones, along with low double-digit percent royalties based on net sales of BCV. All variable transaction amounts are fully constrained, therefore the allocated transaction price is $5.0 million. The majority of the transaction price of the contract has been allocated to the combined performance obligation of the granting of the license to BCV and associated technology transfer which was recognized when the technology transfer was completed in the fourth quarter of 2019. The revenue from regulatory and commercial milestones and royalties from net sales will be recognized upon the occurrence of the triggering events or when those transaction amounts are no longer fully constrained.
Research and Development Prepaids and Accruals	Research and Development Prepaids and Accruals As part of the process of preparing financial statements, the Company is required to estimate its expenses resulting from its obligation under contracts with vendors and consultants and clinical site agreements in connection with its research and development efforts. The financial terms of these contracts are subject to negotiations which vary contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate research and development expenses in its financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of its research and development efforts. The Company determines prepaid and accrual estimates through discussion with applicable personnel and outside service providers as to the progress or state of communication of clinical trials, or other services completed. The Company adjusts its rate of research and development expense recognition if actual results differ from its estimates. The Company makes estimates of its prepaid and accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through September 30, 2020, there had been no material adjustments to the Company’s prior period estimates of prepaid and accruals for research and development expenses. The Company’s research and development prepaids and accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors.
Basic and Diluted Net Loss Per Share of Common Stock	Basic and Diluted Net Loss Per Share of Common Stock Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the period, excluding the dilutive effects of non-vested restricted stock, stock options, and employee stock purchase plan purchase rights. Diluted net loss per share of common stock is computed by dividing net loss by the sum of the weighted-average number of shares of common stock outstanding during the period plus the potential dilutive effects of non-vested restricted stock, stock options, and employee stock purchase plan purchase rights outstanding during the period calculated in accordance with the treasury stock method, but are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during the periods of net loss, there was no difference between basic and diluted loss per share of common stock for the three and nine months ended September 30, 2020 and 2019.
Impact of Recently Issued Accounting Standards and Impact of Recently Adopted Accounting Standards	Impact of Recently Issued Accounting StandardsIn June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach on expected losses to estimate credit losses on certain financial instruments, including trade receivables and available-for-sale debt securities. The new guidance was originally due to become effective for the Company beginning in the first quarter of 2020, however the FASB in November 2019 issued ASU 2019-10 which moved the effective date for smaller reporting companies to the first quarter of 2023. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements.

- Definition

Disclosure of accounting policy for revenue from contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130561-203045

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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 606
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Publisher FASB
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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+ Details

The Business and Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2020

Accounting Policies [Abstract]

Schedule of certain assets measured at fair value on a recurring basis

Below are tables that present information about certain assets measured at fair value on a recurring basis (in thousands):


	Fair Value Measurements
	September 30, 2020
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	34,816	$	34,816	$	—	$	—




Total cash equivalents	34,816		34,816		—		—
Short-term investments

U.S. treasury securities	34,227		34,227		—		—

Commercial paper	3,999		—		3,999		—
Corporate bonds	11,409		—		11,409		—
Total short-term investments	49,635		34,227		15,408		—




Total assets	$	84,451	$	69,043	$	15,408	$	—

	Fair Value Measurements
	December 31, 2019
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents
Money market funds	$	11,854	$	11,854	$	—	$	—



Total cash equivalents	11,854		11,854		—		—
Short-term investments

U.S. treasury securities	22,493		22,493		—		—

Commercial paper	43,119		—		43,119		—
Corporate bonds	30,962		—		30,962		—
Total short-term investments	96,574		22,493		74,081		—





Total assets	$	108,428	$	34,347	$	74,081	$	—

Schedule of accrued liabilities

Accrued liabilities consisted of the following (in thousands):


	September 30, 2020		December 31, 2019
Accrued research and development expenses	$	3,034	$	1,868
Accrued compensation	2,752		3,626
Other accrued liabilities	746		1,336

Total accrued liabilities	$	6,532	$	6,830

Investments (Tables)

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Summary of short-term and long-term investments

The following tables summarize the Company's debt investments (in thousands):


	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Corporate bonds	$	11,381	$	28	$	—	$	11,409

U.S. treasury securities	34,230		2		(5)		34,227
Commercial paper	3,990		9		—		3,999

Total investments	$	49,601	$	39	$	(5)	$	49,635

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Corporate bonds	$	30,952	$	19	$	(9)	$	30,962
Commercial paper	43,109		14		(4)		43,119

U.S. treasury securities	22,478		17		(2)		22,493

Total investments	$	96,539	$	50	$	(15)	$	96,574

Summary of investments with unrealized losses, aggregated by investment type and the length of time


	September 30, 2020
	Less than 12 Months				Greater than 12 Months				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss


U.S. treasury securities	$	25,128	$	(5)	$	—	$	—	$	25,128	$	(5)

Total	$	25,128	$	(5)	$	—	$	—	$	25,128	$	(5)
Number of securities with unrealized losses			8				—				8

	December 31, 2019
	Less than 12 Months				Greater than 12 Months				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss

Corporate bonds	$	9,657	$	(9)	$	—	$	—	$	9,657	$	(9)
Commercial paper	10,147		(4)		—		—		10,147		(4)
U.S. treasury securities	2,994		(2)		—		—		2,994		(2)

Total	$	22,798	$	(15)	$	—	$	—	$	22,798	$	(15)
Number of securities with unrealized losses			9				—				9

Summary of the scheduled maturity of company investments

The following table summarizes the scheduled maturity for the Company's debt investments at September 30, 2020 (in thousands):


Maturing in one year or less	$	49,635
Maturing after one year through two years	—
Total debt investments	$	49,635

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2020

Commitments and Contingencies Disclosure [Abstract]

Operating Lease Right-of-Use Assets and Liabilities

The following table sets forth the operating lease right-of-use assets and liabilities as of September 30, 2020 (in thousands):


Assets
Operating lease right-of-use assets	$	2,943

Liabilities
Operating lease short-term liabilities (recorded within Accrued liabilities)	$	91
Operating lease long-term liabilities (recorded within Lease-related obligations)	2,923
Total operating lease liabilities	$	3,014

Operating Lease Maturity

Operating lease payments over the remainder of the lease terms are as follows (in thousands):


Years Ending December 31,	As of September 30, 2020
2020	$	147
2021 (1)	260
2022	715
2023	736
2024	759
All remaining years	1,248
Total future minimum rental payments	$	3,865
Less amount of lease payments representing interest	851
Total present value of lease payments	$	3,014

As of December 31, 2019, operating lease payments over the remainder of the lease terms were as follows (in thousands):


Years Ending December 31,	As of December 31, 2019

2020	$	719
2021	182


Total future minimum rental payments	$	901
Less amount of lease payments representing interest	66
Total present value of lease payments	$	835

Sublease Income

Total future minimum rentals under the non-cancelable operating sublease are presented below (in thousands):


Years Ending December 31,	As of September 30, 2020

2020	$	21
2021	14


Total future minimum sublease rentals	$	35

Equity Transactions and Share-based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of employee and non-employee share-based compensation expense recognized related to stock options, the ESPP and RSUs

Total share-based compensation expense recognized related to stock options, the ESPP and RSUs was as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development expense	$	625	$	901	$	2,090	$	3,170
General and administrative expense	657		628		1,910		4,799
Total share-based compensation expense	$	1,282	$	1,529	$	4,000	$	7,969

Restructuring Costs (Tables)

9 Months Ended

Sep. 30, 2020

Restructuring and Related Activities [Abstract]

Restructuring and Related Costs

The following table summarizes the restructuring charges (in thousands) recorded in 2019 during the period subsequent to the restructuring in May 2019:


	Employee Termination Benefits		Clinical Trial Close-out Costs		Other Development Costs		Fixed Asset Disposals		Total
Research and development	$	1,437	$	2,021	$	339	$	—	$	3,797
General and administrative	1,909		—		—		—		1.909
Interest income and other, net	—		—		—		250		250
Total restructuring expenses	$	3,346	$	2,021	$	339	$	250	$	5,956

Schedule of Restructuring Reserve by Type of Cost

The following table sets forth the accrual activity for employee termination benefits and contract close-out costs (in thousands) for 2019.


	Employee Termination Benefits		Clinical Trial Close-out Costs		Other Development Costs		Fixed Asset Disposals		Total
Balance at January 1, 2019	$	—	$	—	$	—	$	—	$	—
Accruals	3,335		2,131		315		—		5,781
Revised estimates	11		(621)		24		250		(336)
Payments	(3,163)		(1,483)		(229)		(250)		(5,125)
Balance at December 31, 2019	$	183	$	27	$	110	$	—	$	320

The following table sets forth the accrual activity for employee termination benefits and contract close-out costs (in thousands) for the nine months ended September 30, 2020.


	Employee Termination Benefits		Clinical Trial Close-out Costs		Other Development Costs		Total
Balance at December 31, 2019	$	183	$	27	$	110	$	320

Revised estimates	—		(14)		—		(14)
Payments	(114)		(4)		(100)		(218)
Balance at March 31, 2020	$	69	$	9	$	10	$	88
Revised estimates	—		(5)		—		(5)
Payments	(69)		—		—		(69)
Balance at June 30, 2020	$	—	$	4	$	10	$	14
Revised estimates	—		(4)		(10)		(14)
Payments	—		—		—		—
Balance at September 30, 2020	$	—	$	—	$	—	$	—

The Business and Summary of Significant Accounting Policies - Description of Business (Details)	9 Months Ended
	Sep. 30, 2020 product_candidate
Accounting Policies [Abstract]
Number of product candidates	2

The Business and Summary of Significant Accounting Policies - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Separate Account Investment [Line Items]
Short-term investments	$ 49,635	$ 96,574
Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	34,816	11,854
Short-term investments	49,635	96,574
Total assets	84,451	108,428
Fair value, measurements, recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	34,816	11,854
Short-term investments	34,227	22,493
Total assets	69,043	34,347
Fair value, measurements, recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
Short-term investments	15,408	74,081
Total assets	15,408	74,081
Fair value, measurements, recurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
Short-term investments	0	0
Total assets	0	0
Money market funds \| Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	34,816	11,854
Money market funds \| Fair value, measurements, recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	34,816	11,854
Money market funds \| Fair value, measurements, recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
Money market funds \| Fair value, measurements, recurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0	0
U.S. treasury securities \| Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Short-term investments	34,227	22,493
U.S. treasury securities \| Fair value, measurements, recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	34,227	22,493
U.S. treasury securities \| Fair value, measurements, recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
U.S. treasury securities \| Fair value, measurements, recurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Commercial paper \| Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Short-term investments	3,999	43,119
Commercial paper \| Fair value, measurements, recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Commercial paper \| Fair value, measurements, recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	3,999	43,119
Commercial paper \| Fair value, measurements, recurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Corporate bonds \| Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Short-term investments	11,409	30,962
Corporate bonds \| Fair value, measurements, recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0	0
Corporate bonds \| Fair value, measurements, recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	11,409	30,962
Corporate bonds \| Fair value, measurements, recurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	$ 0	$ 0

The Business and Summary of Significant Accounting Policies - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Accrued research and development expenses	$ 3,034	$ 1,868
Accrued compensation	2,752	3,626
Other accrued liabilities	746	1,336
Total accrued liabilities	$ 6,532	$ 6,830

The Business and Summary of Significant Accounting Policies - Revenue Recognition (Details)	3 Months Ended		9 Months Ended		12 Months Ended	116 Months Ended	121 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Feb. 15, 2021 USD ($) base_segment option_segment revenue_contract	Oct. 31, 2019 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues	$ 1,609,000	$ 1,958,000	$ 4,252,000	$ 5,752,000
BARDA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues	1,600,000	2,000,000.0	4,200,000	5,800,000		$ 74,400,000
BARDA \| Scenario, Forecast
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues							$ 78,900,000
Total number of base segments \| base_segment							1
Total number of option segments \| option_segment							4
Total number of separate contracts \| revenue_contract							5
BARDA \| Expense reimbursement \| Scenario, Forecast
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues							$ 75,800,000
BARDA \| Fees \| Scenario, Forecast
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues							5,300,000
BARDA Fourth Option Segment \| Scenario, Forecast
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues							$ 4,600,000
SymBio Pharmaceuticals
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues					$ 5,000,000.0
Initial upfront payment to be received		5,000,000.0		5,000,000.0				$ 5,000,000.0
Payment to be received upon achievement of milestones	$ 180,000,000.0	$ 180,000,000	$ 180,000,000.0	$ 180,000,000	$ 180,000,000.0	$ 180,000,000.0

Investments - Summary of Available-for-Sale securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Amortized Cost	$ 49,601	$ 96,539
Gross Unrealized Gains	39	50
Gross Unrealized Losses	(5)	(15)
Estimated Fair Value	49,635	96,574
Corporate bonds
Schedule of Investments [Line Items]
Amortized Cost	11,381	30,952
Gross Unrealized Gains	28	19
Gross Unrealized Losses	0	(9)
Estimated Fair Value	11,409	30,962
U.S. treasury securities
Schedule of Investments [Line Items]
Amortized Cost	34,230	22,478
Gross Unrealized Gains	2	17
Gross Unrealized Losses	(5)	(2)
Estimated Fair Value	34,227	22,493
Commercial paper
Schedule of Investments [Line Items]
Amortized Cost	3,990	43,109
Gross Unrealized Gains	9	14
Gross Unrealized Losses	0	(4)
Estimated Fair Value	$ 3,999	$ 43,119

Investments - Summary of Investments with Unrealized Losses, Aggregated by Investment Type and the Length of Time (Details) $ in Thousands	Sep. 30, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	$ 25,128	$ 22,798
Unrealized loss, less than 12 months	(5)	(15)
Fair value, greater than 12 months	0	0
Unrealized loss, greater than 12 months	0	0
Fair value, total	25,128	22,798
Unrealized loss, total	$ (5)	$ (15)
Number of securities with unrealized losses, less than 12 months \| security	8	9
Number of securities with unrealized losses, greater than 12 months \| security	0	0
Number of securities with unrealized losses, total \| security	8	9
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months		$ 9,657
Unrealized loss, less than 12 months		(9)
Fair value, greater than 12 months		0
Unrealized loss, greater than 12 months		0
Fair value, total		9,657
Unrealized loss, total		(9)
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months		10,147
Unrealized loss, less than 12 months		(4)
Fair value, greater than 12 months		0
Unrealized loss, greater than 12 months		0
Fair value, total		10,147
Unrealized loss, total		(4)
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	$ 25,128	2,994
Unrealized loss, less than 12 months	(5)	(2)
Fair value, greater than 12 months	0	0
Unrealized loss, greater than 12 months	0	0
Fair value, total	25,128	2,994
Unrealized loss, total	$ (5)	$ (2)

Investments - Schedule of Investment Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less	$ 49,635
Maturing after one year through two years	0
Total debt investments	$ 49,635	$ 96,574

Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) ft²	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) ft²	Sep. 30, 2019 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Weighted average remaining lease term	6 years 10 days		6 years 10 days
Rent expense under non-cancelable operating leases	$ 184	$ 187	$ 550	$ 563
Weighted average discount rate	7.93%		7.93%
Lease payments	$ 181	188	$ 538	574
Area of sublease space (in sq ft) \| ft²	3,537		3,537
Sublease income	$ 18	$ 18	$ 53	$ 53

Commitments and Contingencies - Operating Lease Right-of-Use Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Operating lease right-of-use assets	$ 2,943	$ 709
Liabilities
Operating lease short-term liabilities (recorded within Accrued liabilities)	91
Operating lease long-term liabilities (recorded within Lease-related obligations)	2,923	196
Total present value of lease payments	$ 3,014	$ 835
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent

Commitments and Contingencies - Maturity Analysis of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 147	$ 719
2021	260	182
2022	715
2023	736
2024	759
All remaining years	1,248
Total future minimum rental payments	3,865	901
Less amount of lease payments representing interest	851	66
Total present value of lease payments	$ 3,014	$ 835
Lease extension term	65 months
Rent abatement term	5 months

Commitments and Contingencies - Minimum Sublease Rentals (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 21
2021	14
Total future minimum sublease rentals	$ 35

Equity Transactions and Share-based Compensation (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jan. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued for restricted stock units (in shares)		277,000	50,000	440,000	419,000
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Acceleration compensation					$ 1.8
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Acceleration compensation					$ 0.7
The 2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Evergreen option provision, equity increase				4.00%
Additional shares authorized (in shares)	2,500,000
Number of shares reserved for future issuance (in shares)		3,400,000		3,400,000
Shares issued pursuant to the exercise of stock options (in shares)		21,000	5,000	263,000	19,000
The 2013 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Evergreen option provision, equity increase				1.00%
Additional shares authorized (in shares)	422,535
Number of shares reserved for future issuance (in shares)		2,400,000		2,400,000
Number of shares authorized to be granted (in shares)		3,500,000		3,500,000
Number of shares reserved for issuance, annual increase (in shares)				422,535
Participation term				24 months
Percentage of pay that employee can contribute, maximum		15.00%		15.00%
Discounted purchase price from market price, offering date				15.00%
Discounted purchase price from market price, purchase date				15.00%
Purchase interval				6 months
Shares issued pursuant to employee stock purchase plan (in shares)		160,000	96,000	337,000	209,000

Equity Transactions and Share-based Compensation - Schedule of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	$ 1,282	$ 1,529	$ 4,000	$ 7,969
Research and development expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	625	901	2,090	3,170
General and administrative expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	$ 657	$ 628	$ 1,910	$ 4,799

Income Taxes - Narrative (Details) - USD ($)	9 Months Ended	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2021
Income Tax Contingency [Line Items]
Federal or state income taxes	$ 0
Unrecognized tax benefits	$ 0
Scenario, Forecast
Income Tax Contingency [Line Items]
Estimated annual effective tax rate		0.00%

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Significant Agreements (Details) shares in Millions			1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended	116 Months Ended	121 Months Ended
Significant Agreements (Details) shares in Millions	Oct. 01, 2019	Jul. 26, 2019 USD ($) shares	Feb. 28, 2011 extension	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Feb. 15, 2021 USD ($)	Oct. 31, 2019 USD ($)
Long-term Purchase Commitment [Line Items]
Total revenues				$ 1,609,000	$ 1,958,000	$ 4,252,000	$ 5,752,000
BARDA
Long-term Purchase Commitment [Line Items]
Number of extension periods \| extension			4
Total revenues				1,600,000	2,000,000.0	4,200,000	5,800,000		$ 74,400,000
Cantex Pharmaceuticals Inc.
Long-term Purchase Commitment [Line Items]
Upfront cash payment for license and development agreement		$ 30,000,000.0
Shares issued for license and development agreement (in shares) \| shares		10.0
Acquired in-process research and development		$ 65,000,000.0
Transaction costs		100,000
Payments to be made for regulatory milestones (up to)		202,500,000
Payments to be made upon achievement of specified net sales levels (up to)		$ 385,000,000.0
Royalty percentage to be paid (at least)		10.00%
SymBio Pharmaceuticals
Long-term Purchase Commitment [Line Items]
Total revenues								$ 5,000,000.0
Termination notice period	90 days
Initial upfront payment to be received					5,000,000.0		5,000,000.0				$ 5,000,000.0
Payment to be received upon achievement of milestones				$ 180,000,000.0	$ 180,000,000	$ 180,000,000.0	$ 180,000,000	$ 180,000,000.0	$ 180,000,000.0
Scenario, Forecast \| BARDA
Long-term Purchase Commitment [Line Items]
Total revenues										$ 78,900,000
Scenario, Forecast \| BARDA \| Expense reimbursement
Long-term Purchase Commitment [Line Items]
Total revenues										75,800,000
Scenario, Forecast \| BARDA \| Fees
Long-term Purchase Commitment [Line Items]
Total revenues										5,300,000
Scenario, Forecast \| BARDA Fourth Option Segment
Long-term Purchase Commitment [Line Items]
Total revenues										$ 4,600,000

Restructuring Costs (Details) $ in Thousands	1 Months Ended	3 Months Ended				7 Months Ended	9 Months Ended	12 Months Ended
Restructuring Costs (Details) $ in Thousands	May 31, 2019 employee	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Reduction in workforce \| employee	43
One-time employee termination benefits						$ 3,346		$ 3,300
Accrued contract close-out costs						2,021		2,000
Other BCV development costs						339		300
Fixed Asset Disposals						250		300
Accrual balance		$ 0	$ 14	$ 88		320	$ 0	320	$ 0
Restructuring charges					$ (156)	5,956
Revised estimates		(14)	(5)	(14)			(33)	(336)
Proceeds from refund of deposits		1,300
Revision of Prior Period, Adjustment
Restructuring Cost and Reserve [Line Items]
Unused deposits						(1,300)		(1,300)
Other assets						1,300		1,300
Trial Terminations
Restructuring Cost and Reserve [Line Items]
Change in accrual balance								1,500
Accrual balance		0	4	9		27	0	27	0
Revised estimates		(4)	(5)	(14)				(621)
Other Development Costs
Restructuring Cost and Reserve [Line Items]
Accrual balance		0	10	10		110	0	110	0
Revised estimates		(10)	0	0				24
Severance Accrual Balance
Restructuring Cost and Reserve [Line Items]
Accrual balance		0	0	69		$ 183	$ 0	183	$ 0
Revised estimates		$ 0	$ 0	$ 0				$ 11

Restructuring Costs - Summary of Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended	7 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Employee Termination Benefits		$ 3,346		$ 3,300
Clinical Trial Close-out Costs		2,021		2,000
Other Development Costs		339		300
Fixed Asset Disposals		250		$ 300
Total	$ (156)	5,956
Research and development expense
Restructuring Cost and Reserve [Line Items]
Employee Termination Benefits		1,437
Clinical Trial Close-out Costs		2,021
Other Development Costs		339
Fixed Asset Disposals		0
Total	4,400	3,797	$ 4,400
General and administrative expense
Restructuring Cost and Reserve [Line Items]
Employee Termination Benefits		1,909
Clinical Trial Close-out Costs		0
Other Development Costs		0
Fixed Asset Disposals		0
Total	$ 1,900	1,909	$ 1,900
Interest income and other, net
Restructuring Cost and Reserve [Line Items]
Employee Termination Benefits		0
Clinical Trial Close-out Costs		0
Other Development Costs		0
Fixed Asset Disposals		250
Total		$ 250

Restructuring Costs - Accrual Activity for Restructuring Accrual (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended	12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Restructuring Reserve [Roll Forward]
Beginning balance	$ 14	$ 88	$ 320	$ 320	$ 0
Accruals					5,781
Revised estimates	(14)	(5)	(14)	(33)	(336)
Payments	0	(69)	(218)		(5,125)
Ending balance	0	14	88	0	320
Employee Termination Benefits
Restructuring Reserve [Roll Forward]
Beginning balance	0	69	183	183	0
Accruals					3,335
Revised estimates	0	0	0		11
Payments	0	(69)	(114)		(3,163)
Ending balance	0	0	69	0	183
Clinical Trial Close-out Costs
Restructuring Reserve [Roll Forward]
Beginning balance	4	9	27	27	0
Accruals					2,131
Revised estimates	(4)	(5)	(14)		(621)
Payments	0	0	(4)		(1,483)
Ending balance	0	4	9	0	27
Other Development Costs
Restructuring Reserve [Roll Forward]
Beginning balance	10	10	110	110	0
Accruals					315
Revised estimates	(10)	0	0		24
Payments	0	0	(100)		(229)
Ending balance	$ 0	$ 10	10	0	110
Fixed Asset Disposals
Restructuring Reserve [Roll Forward]
Beginning balance			$ 0	$ 0	0
Accruals					0
Revised estimates					250
Payments					(250)
Ending balance					$ 0