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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2019	Mar. 20, 2020	Jun. 28, 2019
Cover [Abstract]
Entity Registrant Name	PLUS THERAPEUTICS, INC.
Entity Central Index Key	0001095981
Trading Symbol	PSTV
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 5.4
Entity Common Stock, Shares Outstanding		3,880,588
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock, par value $0.001
Security Exchange Name	NASDAQ
Entity File Number	001-34375
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0827593
Entity Address, Address Line One	4200 MARATHON BLVD
Entity Address, Address Line Two	SUITE 200
Entity Address, City or Town	AUSTIN
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	78756
City Area Code	(737)
Local Phone Number	255-7194
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement for its 2020 Annual Meeting of Stockholders, which will be filed with the United States Securities and Exchange Commission within 120 days of December 31, 2019, are incorporated by reference into Part III of this Annual Report on Form 10-K.

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 17,552	$ 5,261
Accounts receivable	1,169	178
Restricted cash	40	40
Inventories, net	107	107
Other current assets	957	785
Current assets held for sale		3,277
Total current assets	19,825	9,648
Property and equipment, net	2,179	2,299
Operating lease right-use-of assets	781
Other assets	72	39
Noncurrent assets held for sale		11,633
Goodwill	372	372
Total assets	23,229	23,991
Current liabilities:
Accounts payable and accrued expenses	3,279	2,777
Operating lease liability	147
Term loan obligation, net of discount	11,060	14,202
Current liabilities held for sale		580
Total current liabilities	14,486	17,559
Other noncurrent liabilities	8	46
Noncurrent operating lease liability	646
Warrant liability	6,929	916
Noncurrent liabilities held for sale		245
Total liabilities	22,069	18,766
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; 1,959 and 4,606 shares issued and outstanding in 2019 and 2018, respectively
Common stock, $0.001 par value; 100,000,000 shares authorized; 3,880,588 and 296,609 shares issued and outstanding in 2019 and 2018, respectively	4
Additional paid-in capital	426,426	418,390
Accumulated other comprehensive income		1,218
Accumulated deficit	(425,270)	(414,383)
Total stockholders’ equity	1,160	5,225
Total liabilities and stockholders’ equity	$ 23,229	$ 23,991

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Stockholders’ equity:
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	1,959	4,606
Preferred stock, shares outstanding (in shares)	1,959	4,606
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	3,880,588	296,609
Common stock, shares outstanding (in shares)	3,880,588	296,609

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Development revenues:
Government contracts and other	$ 6,998	$ 2,983
Total development revenues	6,998	2,983
Operating expenses:
Research and development	5,365	5,523
Sales and marketing	468	643
General and administrative	4,822	5,579
Total operating expenses	10,655	11,745
Operating loss	(3,657)	(8,762)
Other income (expense):
Interest income	55	43
Interest expense	(1,855)	(1,922)
Change in fair value of warrants	3,407	2,233
Issuance cost of warrants	(1,233)	(470)
Total other expense	374	(116)
Loss from continuing operations	(3,283)	(8,878)
Loss from discontinued operations	(7,604)	(3,756)
Net loss	(10,887)	(12,634)
Income (Loss) from continuing operations	(3,283)	(8,878)
Beneficial conversion feature for convertible preferred stock	(554)	(2,487)
Net loss allocable to common stockholders - continuing operations	(3,837)	(11,365)
Net loss allocable to common stockholders - discontinued operations	(7,604)	(3,756)
Net loss allocable to common stockholders	$ (11,441)	$ (15,121)
Basic and diluted net loss per share attributable to common stockholders - continuing operations	$ (2.77)	$ (65.37)
Basic and diluted net loss per share attributable to common stockholders - discontinued operations	(5.49)	(21.61)
Net loss per share, basic and diluted	$ (8.27)	$ (86.98)
Basic and diluted weighted average shares used in calculating net loss per share attributable to common stockholders	1,384,012	173,851
Comprehensive loss:
Net loss	$ (10,887)	$ (12,634)
Other comprehensive loss – foreign currency translation adjustments	0	(169)
Comprehensive loss	$ (10,887)	$ (12,803)

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Series C Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member] Series B And C Convertible Preferred Stock	Convertible Preferred Stock [Member] Series B Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member] Series C Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series B And C Convertible Preferred Stock	Common Stock [Member] Series B Convertible Preferred Stock [Member]	Common Stock [Member] Series C Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series C Convertible Preferred Stock [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2017	$ 13,000										$ 413,362		$ 1,387	$ (401,749)
Balance (in shares) at Dec. 31, 2017			2,431				115,651
Share-based compensation	355										355
Sale/Issuance of common stock	1,624	$ 3,041									1,624	$ 3,041
Sale/Issuance of common stock (in shares)						6,723	92,169
Conversion of Convertible Preferred Stock into common stock		8										8
Conversion of Convertible Preferred Stock into common stock (share)					(1,320)	(3,228)			7,921	80,868
Beneficial conversion feature related to Series C Convertible Preferred Stock		2,487										2,487
Accretion of beneficial conversion feature related to Series C Convertible Preferred Stock		(2,487)										(2,487)
Foreign currency translation adjustment and accumulated other comprehensive income	(169)												(169)
Net loss	(12,634)													(12,634)
Balance at Dec. 31, 2018	$ 5,225										418,390		1,218	(414,383)
Balance (in shares) at Dec. 31, 2018	296,609		4,606				296,609
Share-based compensation	$ 127										127
Sale of common stock and pre-funded warrants, net of offering costs	4,421						$ 4				4,417
Sale of common stock and pre-funded warrants, net of offering costs (in shares)							3,000,000
Sale/Issuance of common stock	2,208										2,208
Sale/Issuance of common stock (in shares)							184,666
Conversion of Convertible Preferred Stock into common stock (share)				(2,647)				334,199
Exercise of warrants	490										490
Exercise of warrants (in shares)							65,114
Warrant derivative liability reclasssifiedto equity due to exercise of warrants	794										794
Beneficial conversion feature related to Series C Convertible Preferred Stock		554										554
Accretion of beneficial conversion feature related to Series C Convertible Preferred Stock		$ (554)										$ (554)
Foreign currency translation adjustment and accumulated other comprehensive income	(1,218)												$ (1,218)
Net loss	(10,887)													(10,887)
Balance at Dec. 31, 2019	$ 1,160						$ 4				$ 426,426			$ (425,270)
Balance (in shares) at Dec. 31, 2019	3,880,588		1,959				3,880,588

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Statement Of Stockholders Equity [Abstract]
Sale of stock for common stock and pre funded warrants, offering costs	$ 0.6

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows used in operating activities:
Net loss	$ (10,887)	$ (12,634)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	896	2,004
Amortization of deferred financing costs and debt discount	550	578
Change in fair value of warrants	(3,407)	(2,233)
Allocation of issuance cost associated with warrants	1,233	470
Share-based compensation expense	127	355
Noncash lease expense	12	0
Loss on sale of business	6,508	0
Loss on asset disposal	0	36
Provision for doubtful accounts	0	18
Provision for excess inventory	0	463
Increases (decreases) in cash caused by changes in operating assets and liabilities:
Accounts receivable	(1,203)	(173)
Inventories	259	475
Other current assets	(211)	85
Other assets	263	23
Accounts payable and accrued expenses	(28)	(1,532)
Deferred revenues	29	73
Other long-term liabilities	(47)	17
Net cash used in operating activities	(5,906)	(11,975)
Cash flows from (used in) investing activities:
Purchases of property and equipment	(67)	(133)
Proceeds from sale of business	5,637	0
Net cash provided by (used in) investing activities	5,570	(133)
Cash flows from financing activities:
Principal payments of long-term obligations	(3,692)	0
Payment of financing lease liability	(131)	0
Proceeds from sale of common stock and unit offering, net of offering cost	15,964	0
Proceeds from exercise of warrants	490	0
Proceeds from sale of common and preferred stock	0	7,234
Financial capital expenditures	0	(66)
Net cash provided by financing activities	12,631	7,168
Effect of exchange rate changes on cash and cash equivalents	(4)	16
Net increase (decrease) in cash and cash equivalents	12,291	(4,924)
Cash, cash equivalents, and restricted cash at beginning of period	5,301	10,225
Cash, cash equivalents, and restricted cash at end of period	17,592	5,301
Cash paid during period for:
Interest	1,188	1,331
Supplemental schedule of non-cash investing and financing activities:
Proceeds from sales of business, net, paid directly to lender for principal payment of long-term obligations	3,050	0
Offering cost paid in warrants	213	0
Reclass of warrants upon exercise from liability to equity	794	0
Fair value of Convertible Preferred Stock beneficial conversion feature	554	2,487
Conversion of preferred stock into common	$ 0	$ 8

Organization and Operations

12 Months Ended

Dec. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Operations

1.	Organization and Operations

The Company

Plus Therapeutics, Inc. (formerly known as Cytori Therapeutics, Inc.) is a clinical-stage pharmaceutical company focused on the discovery, development, and manufacturing scale up of complex and innovative treatments for patients battling cancer and other life-threatening diseases.

Principles of Consolidation

The accompanying consolidated financial statements include the Company’s accounts and those of its subsidiaries. All significant intercompany transactions and balances have been eliminated in consolidation.

Up to the sale transactions as described below, the Company had five wholly-owned subsidiaries located in Japan, United Kingdom, Switzerland, India and Spain that have been established primarily to support our sales and marketing activities in these regions.

On March 30, 2019, the Company entered into an Asset and Share Sale and Purchase Agreement (the “Lorem Purchase Agreement”) with Lorem Vascular Pte. Ltd. (“Lorem”), pursuant to which, among other things, Lorem agreed to purchase the Company’s UK subsidiary, Cytori Ltd. (the “UK Subsidiary”), and the Company’s Cell Therapy assets, excluding such assets used in Japan or relating to the Company’s contract with the U.S. Department of Health and Human Service’s Biomedical Advanced Research and Development Authority (“BARDA”). Both the Company and Lorem made customary representations, warranties and covenants in the Lorem Purchase Agreement. The transaction was completed on April 24, 2019 and the Company received $4.0 million of cash proceeds, of which $1.7 million was used to pay down principal, interest and fees under the Loan and Security Agreement, dated May 29, 2015 (the “Loan and Security Agreement”), with Oxford Finance, LLC (“Oxford”).

On April 19, 2019, the Company entered into an Asset and Share Sale and Purchase Agreement (the “Shirahama Purchase Agreement”) with Seijirō Shirahama, pursuant to which, among other things, Mr. Shirahama agreed to purchase the Company’s Japanese subsidiary, Cytori Therapeutics, K.K. (the “Japanese Subsidiary”), and substantially all of the Company’s Cell Therapy assets used in Japan. Both the Company and Mr. Shirahama made customary representations, warranties and covenants in the Shirahama Purchase Agreement. The transaction was completed on April 25, 2019 and the Company received $3.0 million of cash proceeds, of which $1.4 million was used to pay down principal, interest and fees under the Loan and Security Agreement (defined in Note 4).

Amendments to Certificate of Incorporation and Reverse Stock Split

On July 29, 2019, the Company amended its Certificate of Incorporation with the State of Delaware to change its corporate name from Cytori Therapeutics, Inc. to Plus Therapeutics, Inc. The Company also changed its trading symbol for its common stock on the Nasdaq Capital Market to “PSTV”.

On May 23, 2018, following stockholder and Board approval, the Company filed a Certificate of Amendment to its Amended and Restated Certificate of Incorporation, as amended (the “Amendment”), with the Secretary of State of the State of Delaware to (i) effectuate a one-for-ten (1:10) reverse stock split (the “Reverse Stock Split”) of its common stock, par value $0.001 per share, without any change to its par value, and (ii) increase the number of authorized shares of the Company’s common stock from 75 million to 100 million shares (which amount is not otherwise affected by the Reverse Stock Split). The Amendment became effective on the filing date. Upon effectiveness of the Reverse Stock Split, the number of shares of the Company’s common stock (x) issued and outstanding decreased from approximately 61.6 million shares (as of May 23, 2018) to approximately 6.2 million shares; (y) reserved for issuance upon exercise of outstanding warrants and options decreased from approximately 23.4 million shares to approximately 2.3 million shares, and (z) reserved but unallocated under our current equity incentive plans (including the stockholder-approved share increase to the Company’s 2014 Equity Incentive Plan) decreased from approximately 9.1 million common shares to approximately 0.9 million common shares. The Company’s 5,000,000 shares of authorized Preferred Stock were not affected by the Reverse Stock Split. No fractional shares were issued in connection with the Reverse Stock Split. Proportional adjustments for the reverse stock split were made to the Company's outstanding stock options, warrants and equity incentive plans for all periods presented.

On August 5, 2019, following stockholder and Board approval, the Company filed a Certificate of Amendment (the “August 2019 Amendment”) to its Amended and Restated Certificate of Incorporation (the Amendment), as amended, with the Secretary of State of the State of Delaware to effectuate a one-for-fifty (1:50) reverse stock split (the “August 2019 Reverse Stock Split”)) of its common stock, par value $0.001 per share, without any change to its par value. The August 2019 Amendment became effective on the filing date. The August 2019 Reverse Stock Split became effective for trading purposes as of the commencement of trading on the Nasdaq Capital Market on August 6, 2019. Upon effectiveness, each 50 shares of issued and outstanding common stock were converted into one newly issued and outstanding share of common stock. The Company’s 5,000,000 shares of authorized Preferred Stock were not affected by the August 2019 Reverse Stock Split. No fractional shares were issued in connection with the August 2019 Reverse Stock Split. Any fractional shares of common Stock that would have otherwise resulted from the August 2019 Reverse Stock Split were rounded up to the nearest whole share. Outstanding equity awards and the shares available for future grant under the Company’s 2014 Amended and Restated Equity Incentive Plan and 2015 New Employee Incentive Plan were proportionately reduced (rounded down to the nearest whole share), and the exercise prices of outstanding equity awards were proportionately increased (rounded up to the nearest whole cent) to give effect to the August 2019 Reverse Stock Split.

Certain Risks and Uncertainties

The Company’s prospects are subject to the risks and uncertainties frequently encountered by companies in the early stages of development and commercialization, especially those companies in rapidly evolving and technologically advanced industries such as the biotech/medical device field. The Company’s future viability largely depends on its ability to complete development of new products and receive regulatory approvals for those products. No assurance can be given that the Company’s new products will be successfully developed, regulatory approvals will be granted, or acceptance of these products will be achieved.

Liquidity and Going Concern

The Company incurred net losses of $10.9 million for the year ended December 31, 2019, and it had an accumulated deficit of $425.3 million as of December 31, 2019. Additionally, the Company used net cash of $5.9 million to fund its operating activities for the year ended December 31, 2019. In addition, as discussed in Note 13, the full magnitude of the coronavirus pandemic on the Company’s financial condition, liquidity and future results of operations is uncertain. These factors raise substantial doubt about the Company’s ability to continue as a going concern.

In September 2019, the Company finalized the indirect cost rate under the BARDA Agreement for indirect costs incurred during the years 2012 through 2019, which resulted in approximately $4.6 million of revenue recognized during the year ended December 31, 2019.

In September 2019, the Company entered into an underwriting agreement with H.C. Wainwright & Co., LLC (the “Representative”), as representative of the underwriters (the “Underwriters”), pursuant to which the Company sold in an underwritten public offering an aggregate of (i) 289,000 Class A Units, each consisting of one share of common stock, par value $0.001 per share, of the Company and one Series U warrant to purchase one share of common stock, and (ii) 2,711,000 Class B Units, each consisting of one pre-funded Series V warrant to purchase one share of common stock and one Series U Warrant to purchase one share of common stock at a public offering price of $5.00 per Class A Unit and $4.9999 per Class B Unit (“September 2019 Offering”). In addition, the Company granted the Underwriters a 45-day option to purchase up to an additional 450,000 shares of the Company’s common stock and/or Series U Warrants at the public offering price, less the underwriting discounts and commissions. The Underwriters exercised their option to purchase an additional 450,000 Series U warrants. The Company also issued to the Representative warrants (in the form of the Series U warrants) to purchase 75,000 shares of common stock with an exercise price of $6.25 per share of common stock (“Representative Warrants”).

On April 24, 2019, the Company received $3.3 million of net cash proceeds related to the sale of the UK Subsidiary and the Cell Therapy assets (excluding such assets used in Japan or relating to the Company’s contract with BARDA), of which $1.7 million was used to pay down principal, interest and fees on the Loan and Security Agreement, and on April 25, 2019 the Company received $2.4 million of net cash proceeds related to the sale of the Japanese Subsidiary, and substantially all of the Company’s Cell Therapy assets used in Japan, of which $1.4 million was used to pay down principal, interests and fees on the Loan and Security Agreement.

On September 21, 2018, the Company entered into a purchase agreement and a registration rights agreement (“Lincoln Park Purchase Agreement”), with Lincoln Park, pursuant to which the Company has the right to sell to Lincoln Park and Lincoln Park is obligated to purchase up to $5.0 million of shares of the Company’s common stock over the 24-month period following October 15, 2018, subject to the satisfaction of certain conditions. Through December 31, 2018, the Company sold a total of 12,802 shares for proceeds of approximately $0.3 million through the Lincoln Park Purchase Agreement. During the year ended December 31, 2019, the Company sold 32,170 shares of through the Lincoln Park Purchase Agreement for proceeds of approximately $0.3 million. The Company believes there an insignificant amount remaining available under this financing facility.

On June 1, 2018, the Company entered into a Sales Agreement with B. Riley FBR, Inc. (“B. Riley FBR”) to sell shares of its common stock having an aggregate offering price of up to $6.5 million from time to time, through an “at the market” equity offering program (the “ATM program”) under which B. Riley FBR will act as sales agent. The ATM Program financing facility has been exhausted and there is no availability remaining under this financing facility.

On July 25, 2018, the Company closed a rights offering originally filed under a Form S-1 registration statement in April 2018 (“2018 Rights Offering”). Pursuant to the 2018 Rights Offering, the Company sold an aggregate of 6,723 units consisting of a total of 6,723 shares of Series C Convertible Preferred Stock, resulting in total net proceeds to the Company of approximately $5.7 million. Refer to Note 11 for additional details on the 2018 Rights Offering.

On August 28, 2018, the Company received a written notice from Nasdaq indicating that, based upon the closing bid price of our common stock for the prior 30 consecutive business days, the Company no longer meet the requirement to maintain a minimum bid price of $1.00 per share, as set forth in Nasdaq Listing Rule 5550(a)(2). In accordance with Nasdaq Listing Rule 5810(c)(3)(A), we were provided an initial period of 180 calendar days, or until February 25, 2019, in which to regain compliance. The Company was granted an additional compliance period of 180 calendar days, or until August 26, 2019, in which to regain compliance after meeting the continued listing requirement for market value of publicly held shares and all other initial listing standards for the Nasdaq Capital Market, with the exception of the bid price requirement, and providing notice to Nasdaq staff of our intent to cure the deficiency during this second compliance period, by effecting a reverse stock split, if necessary. In order to regain compliance with the minimum bid price requirement, the closing bid price of the Company’s common stock must have been at least $1.00 per share for a minimum of ten consecutive business days during the 180-day period.

In August 2019, the Company consummated a 1-for-50 reverse stock split pursuant to which the minimum bid price of our common stock rose above $1.00. On August 29, 2019, the Company received written notice from Nasdaq staff that the Company had regained compliance with the Nasdaq Stock Market Listing Rule 5550(a)(2) concerning our minimum bid price per share of its common stock.

On August 16, 2019, the Company received written notice from the Nasdaq indicating that the Company no longer meets the requirements for continued listing under Nasdaq Listing Rule 5550(a)(4) due to the Company’s failure to meet the minimum 500,000 publicly held shares requirement for continued listing. On September 11, 2019, we received written notice from Nasdaq staff that, based on having 786,807 publicly held shares outstanding as of August 31, 2019, we had regained compliance with Nasdaq Listing Rule 5550(a)(4).

On August 19, 2019, the Company received written notice from Nasdaq indicating that, based on the Company’s stockholders’ deficit of $6.3 million as of June 30, 2019, as reported in the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2019, it is no longer in compliance with the minimum stockholders’ equity requirement for continued listing on the Nasdaq Capital Market under Nasdaq Listing Rule 5550(b)(1), which requires listed companies to maintain stockholders’ equity of at least $2.5 million.

Based on the Company’s stockholders’ equity of $1.2 million as of December 31, 2019, the Company does not meet the minimum stockholders’ equity requirement for continued listing on the Nasdaq Capital Market under Nasdaq Listing Rule 5550(b)(1). The Company expects to receive written notice from Nasdaq staff to that effect following the filing of this Annual Report on Form 10-K.

The Company continues to seek additional capital through strategic transactions and from other financing alternatives. Without additional capital, current working capital and cash generated from sales will not provide adequate funding to make debt repayments, for research, sales and marketing efforts and product development activities at their current levels. If sufficient capital is not raised, the Company will at a minimum need to significantly reduce or curtail its research and development and other operations, and this would negatively affect its ability to achieve corporate growth goals.

Should the Company fail to raise additional cash from outside sources, this would have a material adverse impact on its operations.

The accompanying consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from uncertainty related to its ability to continue as a going concern.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions affecting the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting period. The most significant estimates and critical accounting policies involve recognizing revenue, reviewing assets for impairment, determining the assumptions used in measuring share-based compensation expense, valuing warrants and valuing allowances for doubtful accounts.

Actual results could differ from these estimates. Management’s estimates and assumptions are reviewed regularly, and the effects of revisions are reflected in the consolidated financial statements in the periods they are determined to be necessary.

Cash and cash equivalents

The Company considers all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents.

Cash and cash equivalents includes cash in readily available checking and savings accounts. The Company held no investments as of December 31, 2019 and 2018. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institution in which those deposits are held.

Restricted Cash

Restricted cash consists of cash invested in certificate of deposits used as collateral for the issuance of letters of credit pursuant to lease agreements for leasing of property at 3020 and 3030 Callan Road, San Diego, CA, which requires us to execute a letter of credit for $40,000 and $40,000 naming the landlord as a beneficiary as of December 31, 2019 and 2018, respectively.

Accounts Receivable

Accounts receivable are recorded at the invoiced amount and do not bear interest. As of December 31, 2019, accounts receivable represents outstanding invoices under the contract BARDA for work performed prior to the BARDA contract termination.

Property and Equipment

Property and equipment are stated at cost, net of accumulated depreciation. Depreciation expense, which includes the amortization of capitalized leasehold improvements, is provided for on a straight-line basis over the estimated useful lives of the assets, or the life of the lease, whichever is shorter, and range from three to five years. When assets are sold or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and the resulting gain or loss, if any, is included in operations. Maintenance and repairs are charged to operations as incurred.

Impairment

The Company assesses its property and equipment for potential impairment when there is a change in circumstances that indicates carrying values of assets may not be recoverable. Such long-lived assets are deemed to be impaired when the undiscounted cash flows expected to be generated by the asset (or asset group) are less than the asset’s carrying amount. Any required impairment loss would be measured as the amount by which the asset’s carrying value exceeds its fair value, and would be recorded as a reduction in the carrying value of the related asset and a charge to operating expense. The Company recognized no impairment losses during any of the periods presented in these financial statements.

Goodwill

The Company’s goodwill represents the excess of the cost over the fair value of net assets acquired from its business combinations. The determination of the value of goodwill arising from business combinations requires extensive use of accounting estimates and judgments to allocate the purchase price to the fair value of the net tangible and intangible assets acquired.

Goodwill is not amortized; however, it is assessed for impairment using fair value measurement techniques on an annual basis or more frequently if facts and circumstance warrant such a review. Goodwill considered to be impaired if the Company determines that the carrying value of the reporting unit exceeds its fair value.

The Company performs its impairment test annually during the fourth quarter by comparing the Company’s estimated fair value, calculated from the Company’s market capitalization, to its carrying amount. The Company’s annual evaluation for impairment of goodwill consists of one reporting unit. The Company completed its most recent annual evaluation for impairment as of December 31, 2019, and determined that no impairment existed and, consequently, no impairment charge has been recorded during the year.

Warrant Liability

Warrants are accounted for in accordance with the applicable authoritative accounting guidance as either derivative liabilities or as equity instruments depending on the specific terms of the agreements. Liability-classified instruments are recorded at fair value at each reporting period with any change in fair value recognized as a component of change in fair value of derivative liabilities in the consolidated statements of operations and comprehensive loss.

	As of December 31, 2019			As of December 31, 2018
Expected term	1.1 years			2.1 years
Common stock market price	$	2.40		$	14.50
Risk-free interest rate		1.59	%		2.48	%
Expected volatility		168	%		125	%
Resulting fair value (per warrant)	$	1.47		$	6.50

Expected volatility was computed using daily pricing observations of traded shares of the Company for recent periods that correspond to the expected term of the warrants. The Company believes this method produces an estimate that is representative of our expectations of future volatility over the expected term of these warrants. The Company currently has no reason to believe future volatility over the expected remaining life of these warrants is likely to differ materially from historical volatility. The expected life is based on the remaining contractual term of the warrants. The risk-free interest rate is the U.S. Treasury bond rate as of the valuation date.

Fluctuations in the fair value of the warrants are impacted by unobservable inputs. Significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.

Refer to Note 3 for a discussion of the change in the Level 3 warrant liability value.

Revenue Recognition

Development Revenues

The Company earns revenue for performing tasks under research and development agreements with governmental agencies like BARDA. Revenues derived from reimbursement of direct out-of-pocket expenses for research costs associated with government contracts are recorded as government contract and other within development revenues. Government contract revenue is recorded at the gross amount of the reimbursement. The costs associated with these reimbursements are reflected as a component of research and development expense in our statements of operations. The Company recognized $7.0 million and $3.0 million in BARDA revenue for the years ended December 31, 2019 and 2018, respectively.

Concentration of Significant Customers & Geographical Sales

After the Company sold its Cell Therapy business, BARDA accounted for 100% of our revenue from continuing operations which are recognized for year ended December 31, 2019 and 2018 and accounted for 100% of total outstanding accounts receivable presented in the accompanying consolidated financial statements.

Research and Development

Research and development expenditures, which are charged to operations in the period incurred, include costs associated with the design, development, testing and enhancement of the Company’s products, regulatory fees, the purchase of laboratory supplies, and pre-clinical and clinical studies as well as salaries and benefits for our research and development employees.

Also included in research and development expenditures are costs incurred to support the government reimbursement contract, including $1.5 million and $2.7 million of qualified expenses that were incurred for the years ended December 31, 2019 and 2018, related to our government contract with BARDA.

Deferred Financing Costs and Other Debt-Related Costs

Deferred financing costs are capitalized, recorded as an offset to debt balances and amortized to interest expense over the term of the associated debt instrument using the effective interest method. If the maturity of the debt is accelerated because of default or early debt repayment, then the amortization would be accelerated.

Income Taxes

Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income (loss) in the years in which those temporary differences are expected to be recovered or settled. Due to our history of losses, a full valuation allowance has been recognized against our deferred tax assets.

The Company’s policy is to recognize interest and penalties related to income tax matters in income tax expense. For the years ended December 31, 2019 and 2018, the Company has not recorded any interest or penalties related to income tax matters. The Company does not foresee any material changes to unrecognized tax benefits within the next twelve months.

Share-Based Compensation

The Company recognizes the fair value of all share-based payment awards in our statements of operations over the requisite vesting period of each award, which approximates the period during which the employee and non-employee director is required to provide service in exchange for the award. The Company estimates the fair value of these options using the Black-Scholes option pricing model using assumptions for expected volatility, expected term, and risk-free interest rate. Expected volatility is based primarily on historical volatility and is computed using daily pricing observations for recent periods that correspond to the expected term of the options. The expected term is calculated based on historical data for and applied to all employee awards as a single group as the Company does not expect (nor does historical data suggest) substantially different exercise or post-vesting termination behavior amongst our employee population. The risk-free interest rate is the interest rate for treasury instruments with maturities that approximate the expected term.

Segment Information

For the years ended December 31, 2019 and 2018, the Company is managed as a single operating segment, therefore we report our results in one operating segment.

Loss Per Share

Basic per share data is computed by dividing net income or loss applicable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted per share data is computed by dividing net income or loss applicable to common stockholders by the weighted average number of common shares outstanding during the period increased to include, if dilutive, the number of additional common shares that would have been outstanding as calculated using the treasury stock method. Potential common shares were related entirely to outstanding but unexercised options, warrants and convertible preferred stocks for all periods presented.

The Company excluded all potentially dilutive securities from the calculation of diluted loss per share attributable to common stockholders for the years ended December 31, 2019 and 2018, as their inclusion would be antidilutive.

Recently Issued and Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. The standard amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses for most financial assets and certain other instruments that aren’t measured at fair value through net income. For available-for-sale debt securities, entities will be required to recognize an allowance for credit losses rather than a reduction in carrying value of the asset. Entities will no longer be permitted to consider the length of time that fair value has been less than amortized cost when evaluating when credit losses should be recognized. This new guidance is effective in the first quarter of 2023 for calendar-year SEC filers that are smaller reporting companies as of the one-time determination date. Early adoption is permitted beginning in 2019. The Company plans to adopt the new guidance on January 1, 2023, and it does not expect that adoption of this standard will have an impact on its consolidated financial statements and related disclosures.

Recently Adopted Accounting Pronouncements

In February 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment, to simplify how all entities assess goodwill for impairment by eliminating Step 2 from the goodwill impairment test. As amended, the goodwill impairment test will consist of one step comparing the fair value of a reporting unit with its carrying amount. An entity should recognize a goodwill impairment charge for the amount by which the reporting unit's carrying amount exceeds its fair value. This update is effective for annual periods beginning after December 15, 2019, and interim periods within those periods. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company adopted this ASU as of January 1, 2019 and the adopted did not have a material impact on the consolidated financial statements and related disclosures.

In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-02, Leases. Under this new guidance, at the commencement date, lessees will be required to recognize (i) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis and (ii) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. This guidance is not applicable for leases with a term of 12 months or less. The Company adopted ASC 842 as of January 1, 2019, electing the optional transition method that allows for a cumulative-effect adjustment in the period of adoption and did not restate prior periods. The Company elected the package of practical expedients permitted under the transition guidance. As a result of the adoption, the Company recorded right-of-use assets and liabilities. As of December 31, 2019, the Company’s right-of-use assets and liabilities were $0.8 million associated with its operating leases.

In June 2018, the FASB issued ASU No. 2018‑07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, which amends the FASB Accounting Standards Codification in order to simplify the accounting for share-based payments granted to nonemployees for goods and services. Under the ASU, most of the guidance on such payments to nonemployees will be aligned with the requirements for share-based payments granted to employees. The guidance mandates the modified retrospective approach and is effective for annual and interim reporting periods beginning after December 31, 2018, with early adoption permitted. The Company adopted this ASU as of January 1, 2019 and the adoption did not have an impact on the Company’s consolidated financial statements.

Fair Value

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value

3.	Fair Value

Measurements

Fair value measurements are market-based measurements, not entity-specific measurements. Therefore, fair value measurements are determined based on the assumptions that market participants would use in pricing the asset or liability. We follow a three-level hierarchy to prioritize the inputs used in the valuation techniques to derive fair values. The basis for fair value measurements for each level within the hierarchy is described below:

•

Level 1: Quoted prices in active markets for identical assets or liabilities.

•

Level 2: Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs are observable in active markets.

•

Level 3: Valuations derived from valuation techniques in which one or more significant inputs are unobservable in active markets.

Warrants issued by the Company in connection with the 2018 Rights Offering in July 2018 (“Series T Warrants”) and in September 2019 Offering (“Series U Warrants”) are classified as liabilities instruments. Because some of the inputs to our valuation model are either not observable or are not derived principally from or corroborated by observable market data by correlation or other means, the warrant liability is classified as Level 3 in the fair value hierarchy.

The Series T Warrants are not traded in an active securities market, and as such the estimated the fair value as of December 31, 2019 and 2018 was determined by using an option pricing model with the following assumptions:

	As of December 31, 2019			As of December 31, 2018
Expected term	1.1 years			2.1 years
Common stock market price	$	2.40		$	14.50
Risk-free interest rate		1.59	%		2.48	%
Expected volatility		168	%		125	%
Resulting fair value (per warrant)	$	1.47		$	6.50

The warrants issued in connection with the 2018 Rights Offering may be redeemed by the Company at $0.01 per warrant prior to their expiration if the Company’s common stock closes above $3.63 per share, subject to adjustment, for 20 consecutive trading days. The initial fair value of the liability associated with these warrants was $3.1 million, and the fair value decreased to $0.1 million as of December 31, 2019. The main driver for the change in the fair value of warrants at December 31, 2019 and 2018, was related to the change in our stock price.

The Company estimated the fair value of the Series U Warrants on the issuance date as well as at December 31, 2019 with the Black Scholes model. The Series U warrants will be marked to market as of each balance sheet date until they are exercised or upon expiration, with the changes in fair value recorded as non-operating income or loss in the statement of operations and comprehensive income (loss).

	As of December 31, 2019			As of September 25, 2019
Expected term	4.75 years			5 years
Common stock market price	$	2.40		$	3.42
Risk-free interest rate		1.68	%		1.60	%
Expected volatility		134.5	%		134.9	%
Resulting fair value (per warrant)	$	1.94		$	2.90

The following table summarizes the change in our Level 3 warrant liability value (in thousands):

	Years ended December 31,
Warrant liability	2019			2018
Beginning balance	$	916		$	3,148
Issuance of warrants		10,214			—
Exercises		(794	)		—
Change in fair value		(3,407	)		(2,233	)
Ending balance	$	6,929		$	916

Financial Instruments

Fair value information is disclosed about all financial instruments, whether or not recognized in the balance sheets, for which it is practicable to estimate fair value. The disclosures of estimated fair value of financial instruments at December 31, 2019 and 2018, were determined using available market information and appropriate valuation methods. Considerable judgment is necessary to interpret market data and develop estimated fair value. The use of different market assumptions or estimation methods may have a material effect on the estimated fair value amounts.

The carrying amounts for cash and cash equivalents, accounts receivable, other current assets, accounts payable, accrued expenses and other liabilities approximate fair value due to the short-term nature of these instruments.

At December 31, 2019 and 2018, the aggregate fair value and the carrying value of the Company’s term loan were as follows (in thousands):

	December 31, 2019				December 31, 2018
	Fair Value		Carrying Value		Fair Value		Carrying Value
Debt	$	10,761	$	11,060	$	14,043	$	14,202

Carrying value is net of debt discount of $0.4 million and $0.6 million as of December 31, 2019 and 2018, respectively.

The fair value of debt is classified as Level 3 in the fair value hierarchy as some of the inputs, primarily the effective interest rate, to the valuation model are either not observable quoted prices or are not derived principally from or corroborated by observable market data by correlation or other means.

Nonfinancial Assets and Liabilities

The Company applies fair value techniques on a non-recurring basis, if and when necessary, associated with: (1) valuing potential impairment losses related to goodwill which are accounted for pursuant to the authoritative guidance for intangibles—goodwill and other; and (2) valuing potential impairment losses related to long-lived assets which are accounted for pursuant to the authoritative guidance for property, plant and equipment.

Discontinued Operations

12 Months Ended

Dec. 31, 2019

Discontinued Operations And Disposal Groups [Abstract]

Discontinued Operations

4.	Discontinued Operations

As explained in Note 1, on April 24, 2019 and April 25, 2019, the Company completed the sale of its Cell Therapy business to Lorem and Mr. Shirahama. The following table summarizes the calculation of the loss on sale of the Cell Therapy business, which was finalized during the fourth quarter of 2019 (in thousands):

Consideration received	$	7,000
Transaction costs		(1,363	)
Net cash proceeds		5,637
Less:
Carrying value of business and assets sold		12,145
Net loss on sale of business	$	(6,508	)

There were no assets or liabilities related to discontinued operations as of December 31, 2019. Assets and liabilities related to discontinued operations or held for sale as of December 31, 2018 consisted of the following:

	December 31, 2018
Assets
Current assets held for sale:
Accounts receivable, net	$	108
Inventory, net		2,841
Other current assets		328
	$	3,277
Long-term assets held for sale:
Property and equipment, net		260
Other noncurrent assets		1,866
Goodwill		3,550
Intangible assets, net		5,957
		11,633
Total assets	$	14,910

Liabilities
Current liabilities held for sale:
Accounts payable and accrued liabilities	$	580
Long-term liabilities held for sale:
Other noncurrent liabilities		78
Deferred revenues		167
Noncurrent liabilities	$	245
Total liabilities	$	825

The following table summarizes the results of discontinued operations for the periods presented (in thousands).

	Year ended December 31,
	2019			2018
Product revenue	$	901		$	2,671
License revenue		—			1,000
Total revenues		901			3,671
Cost of revenue		857			2,373
Gross profit		44			1,298
Operating expenses:
Research and development		656			3,099
Sales and marketing		411			1,375
General and administrative		185			760
Total operating expenses		1,252			5,234
Operating loss		(1,208	)		(3,936	)
Other income (expense)		112			180
Loss from discontinued operations	$	(1,096	)	$	(3,756	)
Loss from sale of business		(6,508	)		—
Net loss from discontinued operations	$	(7,604	)	$	(3,756	)

During the year ended December 31, 2019, revenues from discontinued operations were related to the Cell Therapy business. Because of the sale of the Cell Therapy business to Lorem and Mr. Shirahama, all product revenues and costs of product revenues for these periods have been recorded in loss from discontinued operations in the consolidated statements of operations.

Included in the statement of cash flows are the following non-cash adjustments related to the discontinued operations (in thousands):

	For the year ended December 31,
	2019		2018
Depreciation and amortization	$	467	$	1,625
Provision for excess inventory	$	—	$	463
Loss on asset disposal	$	—	$	(36	)

Loss per Share

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Loss per Share

Net loss per share for year ended December 31, 2019 included a deemed dividend of $554,000 due to beneficial conversion feature recorded as a result of the adjustment of the conversion price of Series C Preferred Stock from $39.93 to $7.50 per share in August 2019. Net loss per share for year ended December 31, 2018 included a deemed dividend of $2.5 million to account for the beneficial conversion feature in connection with issuance of Series C Preferred Stock.

The following were excluded from the diluted loss per share calculation for the periods presented because their effect would be anti-dilutive:

	For the Year Ended December 31,
	2019		2018
Outstanding stock options		1,865		3,000
Preferred stock		298,000		95,000
Outstanding warrants		3,637,000		178,000
Total		3,936,865		276,000

Composition of Certain Financial Statement Captions

12 Months Ended

Dec. 31, 2019

Composition Of Certain Financial Statement Captions [Abstract]

Composition of Certain Financial Statement Captions

6.	Composition of Certain Financial Statement Captions

Other Current Assets

As of December 31, 2019 and 2018, other current assets were comprised of the following (in thousands):

	December 31,
	2019		2018
Prepaid services	$	277	$	166
Prepaid insurance		536		564
Other receivables		144		55
	$	957	$	785

Property and Equipment, net

As of December 31, 2019 and 2018, property and equipment, net, were comprised of the following (in thousands):

	December 31,
	2019			2018
Office and computer equipment	$	1,518		$	1,279
Leasehold improvements		1,682			1,682
		3,200			2,961
Less accumulated depreciation		(1,021	)		(662	)
	$	2,179		$	2,299

Depreciation expense totaled $0.4 million and $0.3 million for the years ended December 31, 2019 and 2018, respectively.

Accounts Payable and Accrued Expenses

As of December 31, 2019 and 2018, accounts payable and accrued expenses were comprised of the following (in thousands):

	December 31,
	2019		2018
Accrued expenses	$	791	$	824
Accounts payable		327		721
Accrued payroll and bonus		679		423
Accrued professional fees		332		186
Accrued vacation and compensation		166		192
Accrued R&D studies		858		230
Finance lease obligation - current		120		—
Other current liabilities		6		201
	$	3,279	$	2,777

Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

7.	Commitments and Contingencies

Leases

At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, the Company calculates the associated lease liability and corresponding right-of-use asset upon lease commencement using a discount rate based on the rate implicit in the lease or an incremental borrowing rate commensurate with the term of the lease.

The Company records lease liabilities within current liabilities or long-term liabilities based upon the length of time associated with the lease payments. The Company records its operating lease right-of-use assets as long-term assets. Right-of-use assets for financing leases are recorded within property and equipment, net in the Balance Sheet. Leases with an initial term of 12 months or less are not recorded on the Balance Sheet. Instead, the Company recognizes lease expense for these leases on a straight-line basis over the lease term. In connection with certain operating leases, the Company has security deposits recorded and maintained as restricted cash totaling $40 thousand as of December 31, 2019.

The Company leases laboratory, office and storage facilities in San Antonio, Texas, under operating lease agreements that expire in 2028. The Company also leases certain office space in Austin, Texas under a month-to-month operating lease agreement. In addition, the Company leases certain equipment under various operating and finance leases. The lease agreements generally provide for periodic rent increases, and renewal and termination options. The Company’s lease agreements do not contain any material variable lease payments, residual value guarantees or material restrictive covenants.

Certain leases require the Company to pay taxes, insurance, and maintenance. Payments for the transfer of goods or services such as common area maintenance and utilities represent non-lease components. The Company elected the package of practical expedients and therefore does not separate non-lease components from lease components.

The table below summarizes the Company’s lease liabilities and corresponding right-of-use assets (in thousands, except years and rates):

	December 31, 2019
Assets
Operating	$	781
Financing		134
Total leased assets	$	915

Liabilities
Current:
Operating	$	147
Financing		120
Noncurrent:
Operating	$	646
Financing		8
Total lease liabilities	$	921
Weighted-average remaining lease term (years) - operating leases		6.89
Weighted-average remaining lease term (years) - finance leases		1.08
Weighted-average discount rate - operating leases		7.93	%
Weighted-average discount rate - finance leases		5.00	%

The table below summarizes the Company’s lease costs from its consolidated statements of operations, and cash payments from its consolidated statements of cash flows during year ended December 31, 2019.

	Year ended December 31, 2019
Lease expense:
Operating lease expense	$	225
Finance lease expense:
Depreciation of right-of-use assets		116
Interest expense on lease liabilities		9
Total lease expense	$	350

Cash payment information:
Operating cash used for operating leases	$	213
Financing cash used for financing leases		131
Total cash paid for amounts included in the measurement of lease liabilities	$	344

Total rent expenses for the year ended December 31, 2019 was $0.7 million, which includes leases in the table above, month-to-month operating leases, and common area maintenance charges.

The Company’s future minimum annual lease payments under operating and financing leases at December 31, 2019 are as follows (in thousands):

	Financing Leases			Operating Leases
2020		123			211
2021		7			183
2022		—			123
2023		—			100
Thereafter		—			447
Total minimum lease payments	$	130		$	1,064
Less: amount representing interest		(2	)		(271	)
Present value of obligations under leases		128			793
Less: current portion		(120	)		(147	)
Noncurrent lease obligations	$	8		$	646

Prior to December 2019, the Company also maintained office space for its former corporate headquarters in San Diego, California (the “Lease”). The initial term of the Lease is 63 months and may be extended upon mutual agreement. In connection with a restructuring announced in September 2017, the Company began negotiations with the landlord and in February 2018, announced a buy-out of its obligations with the Lease of approximately $0.6 million, included in the general and administrative expenses.

As of December 31, 2018, future minimum lease payments under the Company’s lease obligations under ASC 840 were as follows:

Years Ending December 31,	Obligation
2019	$	1,282
2020		638
2021		638
2022		192
Total	$	2,750

Rent expenses, which includes common area maintenance, for the year ended December 31, 2018 was $1.9 million.

Other commitments

We have entered into agreements with various research organizations for pre-clinical and clinical development studies, which have provisions for cancellation. Under the terms of these agreements, the vendors provide a variety of services including conducting research, recruiting and enrolling patients, monitoring studies and data analysis. Payments under these agreements typically include fees for services and reimbursement of expenses. The timing of payments due under these agreements is estimated based on current study progress. As of December 31, 2019, we have clinical research study obligations of $0.9 million, which is expected to be paid within a year.

We are subject to various claims and contingencies related to legal proceedings. Due to their nature, such legal proceedings involve inherent uncertainties including, but not limited to, court rulings, negotiations between affected parties and governmental actions. Management assesses the probability of loss for such contingencies and accrues a liability and/or discloses the relevant circumstances, as appropriate.

On July 25, 2019, Tap Advisors LLC (“Tap”) filed suit against the Company in the Supreme Court of the State of New York, County of New York, alleging the Company breached an agreement made in 2017, whereby Tap would provide certain financial advisory services to the Company. Tap sought to recover fees of approximately $3.7 million (plus attorneys’ fees) that allegedly had not been paid by the Company related to the sale of its Cell Therapy business in April 2019. In December 2019, the Company settled the Tap litigation with cash payment of $0.7 million, which is included in the loss from discontinued operations for the year ended December 31, 2019.

Term Loan Obligations

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Term Loan Obligations

8.	Term Loan Obligations

On May 29, 2015, the Company entered into the Loan and Security Agreement, with Oxford (the “Loan and Security Agreement”), pursuant to which it funded an aggregate principal amount of $17.7 million (“Term Loan”), subject to the terms and conditions set forth in the Loan and Security Agreement. The Term Loan accrues interest at a floating rate of at least 8.95% per annum, comprised of three-month LIBOR rate with a floor of 1.00% plus 7.95%. Pursuant to the Loan and Security Agreement, we were previously required to make interest only payments through June 1, 2016 and thereafter we were required to make payments of principal and accrued interest in equal monthly installments sufficient to amortize the Term Loan through June 1, 2019, the maturity date. On February 23, 2016, we received an acknowledgement and agreement from Oxford related to the positive data on our U.S. ACT-OA clinical trial. As a result, pursuant to the Loan and Security Agreement, the period for which we are required to make interest-only payments was extended from July 1, 2016 to January 1, 2017. All unpaid principal and interest with respect to the Term Loan was originally due and payable in full on June 1, 2019. The interest-only payment period and maturity date of the Term Loan were further amended as described in more details below. At maturity of the Term Loan, or earlier repayment in full following voluntary prepayment or upon acceleration, we are required to make a final payment in an aggregate amount equal to approximately $1.1 million. In connection with the Term Loan, on May 29, 2015, we issued to Oxford warrants to purchase an aggregate of 188 shares of our common stock at an exercise price of $5,175 per share. These warrants became exercisable as of November 30, 2015 and will expire on May 29, 2025 and, following the authoritative accounting guidance, are equity classified and its respective fair value was recorded as a discount to the debt.

In September 2017 and June 2018, the Company entered into two amendments to the Term Loan which extended the interest-only period, and the Company agreed to pay Oxford an amendment fee of $250,000 at the earlier of maturity or acceleration of the loan.

On August 31, 2018, the Company entered into a third amendment (the “Third Amendment”) to the Term Loan with Oxford. The Third Amendment extends the interest-only period under the Term Loan to December 31, 2018 and also requires that the Company pay to Oxford, in accordance with its pro rata share of the loans, 75% of all proceeds received (i) from the issuance and sale of unsecured subordinated convertible debt, (ii) in connection with a joint venture, collaboration or other partnering transaction, (iii) in connection with any licenses, (iv) from dividends (other than non-cash dividends from wholly owned subsidiaries) and (v) from the sale of any assets (such requirement, the “Prepayment Requirement”). The Prepayment Requirement does not apply to proceeds from the sale and issuance of the Company’s equity securities, other than convertible debt. The Prepayment Requirement shall apply until an aggregate principle amount of $7.0 million has been paid pursuant to the Prepayment Requirement. However, if less than $7.0 million has been paid pursuant to the Prepayment Requirement on December 31, 2018 then the Company is required to promptly make additional payments until an aggregate principal amount of $7.0 million has been paid. The Company agreed to pay Oxford an amendment fee of $50,000 at the earlier of maturity or acceleration of the loan.

On December 31, 2018, the Company entered into a fourth amendment (the “Fourth Amendment”) to the Term Loan with Oxford. Oxford agreed to extend the maturity date from June 1, 2019 to June 1, 2020. The Amendment increases the minimum liquidity covenant level from $1.5 million to $2.0 million and extends the interest-only period under the Loan Agreement to March 1, 2019. The Amendment also requires that the Company achieve one of the following by January 31, 2019: enter into an asset sale agreement with a minimum unrestricted net cash proceeds to the Company of $4.0 million; enter into a binding agreement for the issuance and sale of its equity securities or unsecured convertible subordinated debt which would result in unrestricted gross cash proceeds of not less than $7.5 million; or enter into a merger agreement pursuant to which the obligations under the Loan Agreement would be paid down to a level satisfactory to Oxford. The Company agreed to pay Oxford an amendment fee of $350,000 at the earlier of maturity or acceleration of the loan.

On February 13, 2019, the Company entered into a fifth amendment of the loan agreement to primarily extend the January 31, 2019 obligations under the Fourth Amendment to February 28, 2019. On March 4, 2019, the Company entered into a sixth amendment of the loan agreement to primarily extend the February 13, 2019 obligations under the fifth amendment to March 29, 2019.

On April 29, 2019, the Company entered into a seventh amendment (the “Seventh Amendment”) to the Term Loan, pursuant to which, among other things, Oxford agreed to interest only payments starting May 1, 2019, with amortization payments resuming on May 1, 2020. On July 15, 2019, the Company entered into an eighth amendment (the “Eighth Amendment”) to the Term Loan primarily to obtain the consent from Oxford for its name change to Plus Therapeutics, Inc.

As described in more detail in Note 13, on March 29, 2020 the Company entered into a ninth amendment to the Loan and Security Agreement (the “Ninth Amendment”).

The Term Loan, as amended, is collateralized by a security interest in substantially all of the Company’s existing and subsequently acquired assets, including its intellectual property assets, subject to certain exceptions set forth in the Loan and Security Agreement, as amended. The intellectual property asset collateral will be released upon the Company achieving certain liquidity levels when the total principal outstanding under the Loan Agreement is less than $3 million. As of December 31, 2019, we were in compliance with all of the debt covenants under the Loan and Security Agreement.

The Term Loan Agreement contains customary indemnification obligations and customary events of default, including, among other things, our failure to fulfill certain obligations under the Term Loan, as amended, and the occurrence of a material adverse change, which is defined as a material adverse change in our business, operations, or condition (financial or otherwise), a material impairment of the prospect of repayment of any portion of the loan. In the event of default by us or a declaration of material adverse change by our lender, under the Term Loan, the lender would be entitled to exercise its remedies thereunder, including the right to accelerate the debt, upon which we may be required to repay all amounts then outstanding under the Term Loan, which could materially harm our financial condition. As of December 31, 2019, we were in compliance with all covenants under the Term Loan and have not received any notification or indication from Oxford to invoke the material adverse change clause. However, due to our current cash flow position and the substantial doubt about our ability to continue as a going concern, the entire principal amount of the Term Loan has been reclassified to short-term. We will continue to evaluate the debt classification on a quarterly basis and evaluate for reclassification in the future should our financial condition improve.

Additional details relating to the outstanding Term Loan as of December 31, 2019 and 2018 are presented in the following table (in thousands):

Year ended December 31, 2019

Origination Date

Original

Loan

Amount

Interest

Rate**

Current

Monthly

Payment***

Original

Term

Remaining

Principal

(Face Value)

May 2015

17,700

8.95

48 Months

9,288

Year ended December 31, 2018

Origination Date

Original

Loan

Amount

Interest

Rate**

Current

Monthly

Payment*

Original

Term

Remaining

Principal

(Face Value)

May 2015

17,700

8.95

100

48 Months

12,980

*	Monthly payment as of December 2018, which reflects interest only

**	3 month LIBOR rate with a floor of 1% plus 7.95%

***	Monthly payment as of December 2019, which reflects interest only

As of December 31, 2019, the future contractual principal and final fee payments on all of our debt obligations are as follows (as thousands):

Years Ending December 31,
2020	$	5,308
2021		6,180
Total	$	11,488

Reconciliation of Face Value to Book Value as of December 31, 2019
Total debt obligations, including final payment fee (Face Value)	$	11,488
Less: Debt discount		(428	)
Total obligation	$	11,060

Our interest expense for the years ended December 31, 2019 and 2018 was $1.9 million and $1.9 million, respectively. Interest expense is calculated using the effective interest method, therefore it is inclusive of non-cash amortization in the amount of $0.5 million and $0.6 million, respectively, related to the amortization of the debt discount, capitalized loan costs, and accretion of final payment.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

9.	Income Taxes

The Company has recorded a full valuation allowance against deferred tax assets and due to our net losses for the years ended December 31, 2019 and 2018, there was no provision or benefit for income taxes recorded.

The components of income/(loss) from continuing operations before income tax provision (benefit) as of December 31, 2019 and 2018 are as follows (in thousands):

	2019			2018
U.S.	$	(3,439	)	$	(8,346	)
Foreign		403			(507	)
	$	(3,036	)	$	(8,853	)

A reconciliation of the total income tax provision tax rate to the statutory federal income tax rates of 21% for the years ended December 31, 2019 and 2018, respectively, is as follows:

	2019			2018
Income tax expense (benefit) at federal statutory rate		(21.0	)%		(21.0	)%
Income tax expense (benefit) at state statutory rate		(12.2	)%		(6.1	)%
Change in valuation allowance		23.0	%		34.8	%
Change in state rate		(1.3	)%		(0.1	)%
Permanent interest adjustments		1.1	%		0.7	%
Stock compensation		13.7	%		1.8	%
Research credit		(1.8	)%		(1.4	)%
Return to provision		3.1	%		(3.4	)%
NOLs expiring and adjustments to NOL		19.2	%		—
Mark to market adjustment		(24.0	)%		(5.3	)%
Other, net		0.2	%		—
		0.0	%		(0.0	)%

The tax effects of temporary differences that give rise to significant portions of our deferred tax assets and deferred tax liabilities as of December 31, 2019 and 2018 are as follows (in thousands):

	2019			2018
Deferred tax assets:
Allowances and reserves	$	6		$	270
Accrued expenses		283			122
Stock based compensation		657			996
Net operating loss carryforwards		92,659			91,197
Income tax credit carryforwards		8,749			8,671
Property and equipment, principally due to differences in depreciation		95			548
Intangible assets		370
Other, net		217			38
		103,036			101,842
Valuation allowance		(102,822	)		(101,091	)
Total deferred tax assets, net of allowance		214			751
Deferred tax liabilities:
Other		(214	)		(751	)
Total deferred tax liability		(214	)		(751	)
Net deferred tax assets (liability)	$	—		$	—

The Company has established a valuation allowance against its net deferred tax assets due to the uncertainty surrounding the realization of such assets. The Company periodically evaluates the recoverability of the deferred tax assets. At such time as it is determined that it is more likely than not that deferred assets are realizable, the valuation allowance will be reduced. The Company has recorded a full valuation allowance of $102.8 million as of December 31, 2019 as it does not believe it is more likely than not our net deferred tax assets will be realized. The Company increased its valuation allowance by approximately $1.7 million during the year ended December 31, 2019.

At December 31, 2019, we had federal, and state tax loss carry forwards of approximately $386.8 million, and $161.9 million, respectively. The federal and state net operating loss carry forwards begin to expire in 2020 and 2028, respectively, if unused. The federal net operating loss carryover includes $21.9 million of net operating losses generated in 2018. Federal net operating losses generated from 2018 onwards carryover indefinitely and may generally be used to offset up to 80% of future taxable income. At December 31, 2019, we had federal and state tax credit carry forwards of approximately $6.4 million and $5.5 million, respectively, after reduction for uncertain tax positions. The Company has not performed a formal research and development credit study with respect to these credits. The federal credits will begin to expire in 2020, if unused, and the state credits carry forward indefinitely.

Pursuant to the Internal Revenue Code (“IRC”) of 1986, as amended, specifically IRC §382 and IRC §383, The Company’s ability to use net operating loss and R&D tax credit carry forwards (“tax attribute carry forwards”) to offset future taxable income is limited if we experience a cumulative change in ownership of more than 50% within a three-year testing period. The Company has not completed an ownership change analysis pursuant to IRC Section 382 for taxable years ended after December 31, 2007. If ownership changes within the meaning of IRC Section 382 are identified as having occurred subsequent to 2007, the amount of remaining tax attribute carry forwards available to offset future taxable income and income tax expense in future years may be significantly restricted or eliminated. Further, the Company’s deferred tax assets associated with such tax attributes could be significantly reduced upon realization of an ownership change within the meaning of IRC §382.

The Company follows the provisions of income tax guidance which provides recognition criteria and a related measurement model for uncertain tax positions taken or expected to be taken in income tax returns. The guidance requires that a position taken or expected to be taken in a tax return be recognized in the financial statements when it is more likely than not that the position would be sustained upon examination by tax authorities. Tax positions that meet the more likely than not threshold are then measured using a probability weighted approach recognizing the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate settlement. The Company has not recognized any liability for uncertain tax positions as of December 31, 2019 and 2018.

Following is a tabular reconciliation of the unrecognized tax benefits activity during the years ended December 31, 2019 and 2018 (in thousands):

	2019			2018
Unrecognized Tax Benefits – Beginning	$	2,216		$	2,157
Gross increases – tax positions in prior period		—			1
Gross decreases – tax positions in prior period		(18	)		(3	)
Gross increase – current-period tax positions		36			61
Unrecognized Tax Benefits – Ending	$	2,234		$	2,216

The unrecognized tax benefit amounts are reflected in the determination of the Company’s deferred tax assets. If recognized, none of these amounts would affect the Company’s effective tax rate, since it would be offset by an equal reduction in the deferred tax asset valuation allowance. The Company does not foresee material changes to its liability for uncertain tax benefits within the next twelve months.

The Company did not recognize interest related to unrecognized tax benefits in interest expense and penalties in operating expenses as of December 31, 2019.

The Company’s material tax jurisdictions are the United States and California. To its knowledge, the Company is currently not under examination by the Internal Revenue Service or any other taxing authority.

The Company’s tax years for 2016 (federal) and 2015 (CA) remain open to examination by the taxing authority. While not open to examination, the tax attributes generated in tax years 1998 (federal) and 1997 (CA) and forward are subject to adjustment by the taxing authorities if utilized in tax years which are still open to examination.

Employee Benefit Plan

12 Months Ended

Dec. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Employee Benefit Plan

10.	Employee Benefit Plan

We implemented a 401(k) retirement savings and profit sharing plan (the “Plan”) effective January 1, 1999. We may make discretionary annual contributions to the Plan, which is allocated to the profit sharing accounts based on the number of years of employee service and compensation. At the sole discretion of the Board of Directors, we may also match the participants’ contributions to the Plan. We made no discretionary or matching contributions to the Plan in 2019 or 2018.

Stockholders' Equity

12 Months Ended

Dec. 31, 2019

Stockholders Equity Note [Abstract]

Stockholders' Equity

11.	Stockholders’ Equity

Preferred Stock

The Company has authorized 5,000,000 shares of preferred stock, par value $0.001 per share. The Company’s Board of Directors is authorized to designate the terms and conditions of any preferred stock we issue without further action by the common stockholders. There were no shares of Series A 3.6% Convertible Preferred Stock outstanding as of December 31, 2019 and 2018. There were 1,021 and 1,112 shares of Series B Convertible Preferred Stock outstanding as of December 31, 2019 and December 31, 2018, respectively. There were 938 and 3,494 shares of Series C Preferred Stock outstanding as of December 31, 2019 and December 31, 2018, respectively.

On July 25, 2018, the Company filed a Certificate of Designation of Preferences, Rights and Limitations of Series C Convertible Preferred Stock (the “Certificate of Designation”) with the Delaware Secretary of State creating a new series of its authorized preferred stock, par value $0.001 per share, designated as the Series C Convertible Preferred Stock (the “Series C Preferred Stock”). The number of shares initially constituting the Series C Preferred Stock was set at 7,000 shares. Pursuant to a registration statement on Form S-1 originally filed on April 27, 2018, as amended, and became effective on July 17, 2018, and related prospectus (as supplemented), the Company registered and distributed to holders of its common stock and Series B Convertible Preferred Stock, at no charge, non-transferable subscription rights to purchase up to an aggregate of 20,000 units each consisting of one share of Series C Preferred Stock and 1,050 warrants for $1,000 per unit. Pursuant to the 2018 Rights Offering, which closed on July 25, 2018, the Company sold an aggregate of 6,723 units, resulting in total net proceeds to the Company of approximately $5.7 million. On August 2, 2019, in connection with a sale of common stock, the Company notified holders of the Company’s Series C Preferred Stock that the conversion price of such stock was reduced from $39.93 to $7.50. The reduction of the effective conversion price of the Series C Preferred Stock resulted in a beneficial conversion feature recorded as a deemed dividend to the Series C Preferred Stock holders in the amount of $554,000. The deemed dividend is recorded as a reduction to loss available for common stockholder for basic and diluted loss per share calculation (Note 5). In addition, on August 2, 2019, the Company notified holders of the Company’s Series T Warrants that the exercise price of such warrants was reduced from $0.7986 to $0.15, so that every 50 Series T warrants can be exercised into one share of common stock at $7.50. On September 25, 2019, in connection with the September 2019 Offering, the exercise price of the Series T Warrants was further adjusted such that every 50 warrants can be exercised into one share of common stock for $3.2132, and the conversion price of the Series C Preferred Stock was reduced from $7.50 to $3.2132.

As of December 31, 2019, there were 3,788,400 outstanding Series T Warrants which can be exercised into in aggregate 75,768 shares of common stock. In addition, there were 938 shares of Series C Preferred Stock that can be exercised into 291,920 shares of common stock.

The fair value of the common stock into which the Series C Preferred Stock was convertible on the date of issuance exceeded the proceeds allocated to the preferred stock, resulting in the beneficial conversion feature that we recognized as a deemed dividend to the preferred stockholders and, accordingly, an adjustment to net loss to arrive at net loss allocable to common stockholders. The Company recorded a deemed dividend within additional paid-in capital of $2.5 million for the year ended December 31, 2018, related to a beneficial conversion feature included in the issuance of our Series C Convertible Preferred Stock.

Common Stock

As mentioned in Note 1, the Company completed the September 2019 Offering. The Company issued 289,000 shares of its common stock, along with pre-funded warrants to purchase 2,711,000 shares of its common stock and Series U Warrants to purchase 3,450,000 shares of its common stock at $5.00 per share. By December 31, 2019, all pre-funded warrants have been exercised. The Series U Warrants remained outstanding as of December 31, 2019 and have a term of five years from the issuance date. In addition, the Company issued warrants to the Representatives to purchase 75,000 shares of its common stock at $6.25 per share with a term of 5.0 years from the issuance date, in the form of Series U Warrants.

In accordance with authoritative guidance, the pre-funded warrants are classified as equity. The Series U Warrants and the Representative Warrants are classified as liabilities due to a contingent obligation for the Company to settle the Series U Warrants with cash upon certain change in control events.

In accordance with authoritative guidance, the proceeds from the September 2019 Offering was allocated using the residual method, first to the Series U Warrants at the full fair value and the remainder to equity. The Series U Warrants and the Representative Warrants are revalued at each balance sheet date with change in fair value recorded as other income or loss in the statement of operations and comprehensive income (loss).

On June 1, 2018, the Company entered into a Sales Agreement with B. Riley FBR to sell shares of its common stock having an aggregate offering price of up to $6.5 million through its ATM program. Through December 31, 2018, the Company sold a total of 79,234 shares for proceeds of approximately $1.7 million through the ATM program.

On September 21, 2018, the Company entered into the Lincoln Park Purchase Agreement with Lincoln Park pursuant to which the Company has the right to sell to Lincoln Park and Lincoln Park is obligated to purchase up to $5.0 million of shares, of the Company’s common stock, over the 24-month period following October 15, 2018. Through December 31, 2018, the Company sold a total of 12,802 shares for proceeds of approximately $0.3 million through the Lincoln Park Purchase Agreement. During the year ended December 31, 2019, 32,170 shares for proceeds of approximately $0.3 million were sold. The Company believes there is an insignificant amount remaining available under this financing facility as of December 31, 2019.

Stock-based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based Compensation

12.	Stock-based Compensation

In August 2014, the Company adopted the 2014 Equity Incentive Plan (the “2014 Plan”), which provides its employees, directors and consultants the opportunity to purchase the Company’s common stock in the form of options (incentive or non-qualified), stock appreciation rights, restricted stock purchase rights, restricted stock bonuses, restricted stock units, performance shares, performance units, cash-based awards other stock-based awards, and deferred compensation awards. The 2014 Plan initially provides for issuance of 530 shares of its common stock. In August 2015, the Company amended the 2014 Plan to add 603 shares to its share pool. In addition, the amendment increased the number of “incentive stock options” which may be issued under the 2014 Plan by an identical amount. In May 2016, May 2017 and May 2018, the Company amended the 2014 Plan to add 666, 4,000, and 15,000 shares, respectively, to its share pool. During 2019, the Company amended the 2014 Plan to add 80,000 shares to its share pool.

On December 29, 2015, the Company adopted the 2015 New Employee Incentive Plan (the “2015 Plan”). Awards under the 2015 Plan may only be made to an employee who has not previously been an employee or member of the Board of any parent or subsidiary, or following a bona fide period of non-employment by the Company or a parent or subsidiary, if he or she is granted such award in connection with his or her commencement of employment with the Company or a subsidiary and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary. The 2015 Plan provides for issuance of 133 shares. In January 2017, the Company amended the 2015 Plan to add 500 shares to its share pool.

As of December 31, 2019, there are 30 shares and 99,699 shares of common stock remaining and available for future issuances under the 2015 and 2014 Plans, respectively, which are exclusive of securities to be issued upon an exercise of outstanding options, warrants, and rights.

In February 2020, the Company amended the 2015 Plan to increase the total number of shares of common stock reserved for issuance under the plan by 250,000 shares.

Stock Options

Generally, options issued under the 2014 Plan, are subject to four-year vesting, and have a contractual term of 10 years. Most options contain one of the following two vesting provisions:

•

12/48 of a granted award will vest after one year of service, while an additional 1/48 of the award will vest at the end of each month thereafter for 36 months, or

•

1/48 of the award will vest at the end of each month over a four-year period.

A summary of activity for the year ended December 31, 2019 and December 31, 2018 is as follows:

	Options			Weighted Average Exercise Price
Balance as of December 31, 2018		2,752		$	4,003.50
Granted		2,800		$	15.69
Expired		(37	)	$	41,692.00
Cancelled/forfeited		(3,650	)	$	1,089.35
Balance as of December 31, 2019		1,865		$	2,968.22

	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Balance as of December 31, 2019		1,865	$	2,968.22		7.20	$	-
Vested and expected to vest at December 31, 2019		1,658	$	3,286.28		7.10	$	-
Exercisable at December 31, 2019		1,133	$	4,729.07		6.50	$	-

There were no stock options exercised in 2019 or 2018.

The fair value of each option awarded during the year ended December 31, 2019 and 2018 was estimated on the date of grant using the Black-Scholes-Merton option valuation model based on the following weighted-average assumptions:

	Years ended December 31,
	2019			2018
Expected term	7.0 years			7.1 years
Risk-free interest rate		2.41	%		2.94	%
Volatility		96.52	%		92.87	%
Dividends		—			—
Resulting weighted average grant date fair value	$	0.26		$	1.74

The weighted average risk-free interest rate represents the interest rate for treasury constant maturity instruments published by the Federal Reserve Board. If the term of available treasury constant maturity instruments is not equal to the expected term of an employee option, we use the weighted average of the two Federal Reserve securities closest to the expected term of the employee option.

The dividend yield has been assumed to be zero as the Company (a) has never declared or paid any dividends and (b) does not currently anticipate paying any cash dividends on its outstanding shares of common stock in the foreseeable future.

Years ended December 31,

2019

2018

Total compensation cost for share-based payment

arrangements recognized in the statement of

operations (net of tax of $0)

127

355

As of December 31, 2019, the total compensation cost related to non-vested stock options and stock awards not yet recognized for all our plans is approximately $58,000, which is expected to be recognized as a result of vesting under service conditions over a weighted average period of 1.39 years.

To settle stock options, the Company issue new shares of our common stock. At December 31, 2019, the Company had an aggregate of 97,866 shares authorized and available to satisfy option exercises under its plans.

Subsequent Events

12 Months Ended

Dec. 31, 2019

Subsequent Events [Abstract]

Subsequent Events

13.Subsequent Events

Term Loan Amendment

On March 29, 2020 the Company entered into the Ninth Amendment of the Loan and Security Agreement, pursuant to which, among other things, Oxford agreed to defer the start date of principal repayment from May 1, 2020 to May 1, 2021. In addition, the Company made a $5.0 million paydown of principal upon execution of the Ninth Amendment. As a result of this Ninth Amendment, the term of the Term Loan has been extended from June 1, 2021 to June 1, 2024, with all other major terms remaining consistent.

License Agreement

On March 29, 2020 the Company entered into an exclusive license agreement with NanoTx, Corp (“NanoTx”) for global development and commercialization of its glioblastoma treatment. Once certain post transaction requirements are met, the Company will make an initial license fee payment of $400,000 in cash and $300,000 in the Company’s common stock, based on a mutually agreed upon price consisting of the Company’s weighted average closing stock prices prior to the issuance of such shares of common stock. This license agreement commits the Company to certain milestone payments to NanoTx for successful completion of various milestones, together with royalty and sales payments based on the successful commercialization of the treatment.

Impact of Coronavirus Outbreak

On January 30, 2020, the World Health Organization (“WHO”) announced a global health emergency because of a new strain of coronavirus originating in Wuhan, China (the “COVID-19 outbreak”) and the risks to the international community as the virus spreads globally beyond its point of origin. In March 2020, the WHO classified the COVID-19 outbreak as a pandemic, based on the rapid increase in exposure globally.

The full impact of the COVID-19 outbreak continues to evolve as of the date of this report. As such, it is uncertain as to the full magnitude that the pandemic will have on the Company’s financial condition, liquidity, and future results of operations. Management is actively monitoring the impact of the global situation on its financial condition, liquidity, operations, suppliers, industry, and workforce. Given the daily evolution of the COVID-19 outbreak and the global responses to curb its spread, the Company is not able to estimate the effects of the COVID-19 outbreak on its results of operations, financial condition, or liquidity for fiscal year 2020.

Financial Statement Schedules

12 Months Ended

Dec. 31, 2019

Valuation And Qualifying Accounts [Abstract]

Financial Statement Schedules

(a) (2)

Financial Statement Schedules.

None.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Use of Estimates

Cash and cash equivalents

The Company considers all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents.

Restricted Cash

Accounts Receivable

Property and Equipment

Impairment

Goodwill

Warrant Liability

	As of December 31, 2019			As of December 31, 2018
Expected term	1.1 years			2.1 years
Common stock market price	$	2.40		$	14.50
Risk-free interest rate		1.59	%		2.48	%
Expected volatility		168	%		125	%
Resulting fair value (per warrant)	$	1.47		$	6.50

Refer to Note 3 for a discussion of the change in the Level 3 warrant liability value.

Revenue Recognition

Development Revenues

Concentration of Significant Customers & Geographical Sales

Research and Development

Deferred Financing Costs and Other Debt-Related Costs

Income Taxes

Share-Based Compensation

Segment Information

For the years ended December 31, 2019 and 2018, the Company is managed as a single operating segment, therefore we report our results in one operating segment.

Loss Per Share

Recently Issued and Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions

	As of December 31, 2019			As of December 31, 2018
Expected term	1.1 years			2.1 years
Common stock market price	$	2.40		$	14.50
Risk-free interest rate		1.59	%		2.48	%
Expected volatility		168	%		125	%
Resulting fair value (per warrant)	$	1.47		$	6.50

Fair Value (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]

Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions

	As of December 31, 2019			As of December 31, 2018
Expected term	1.1 years			2.1 years
Common stock market price	$	2.40		$	14.50
Risk-free interest rate		1.59	%		2.48	%
Expected volatility		168	%		125	%
Resulting fair value (per warrant)	$	1.47		$	6.50

Summary of Change in Level 3 Warrant Liability Value

The following table summarizes the change in our Level 3 warrant liability value (in thousands):

	Years ended December 31,
Warrant liability	2019			2018
Beginning balance	$	916		$	3,148
Issuance of warrants		10,214			—
Exercises		(794	)		—
Change in fair value		(3,407	)		(2,233	)
Ending balance	$	6,929		$	916

Fair Value and Carrying Value of Term Loan

At December 31, 2019 and 2018, the aggregate fair value and the carrying value of the Company’s term loan were as follows (in thousands):

	December 31, 2019				December 31, 2018
	Fair Value		Carrying Value		Fair Value		Carrying Value
Debt	$	10,761	$	11,060	$	14,043	$	14,202

Series T Warrants [Member]

Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]

Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions

	As of December 31, 2019			As of December 31, 2018
Expected term	1.1 years			2.1 years
Common stock market price	$	2.40		$	14.50
Risk-free interest rate		1.59	%		2.48	%
Expected volatility		168	%		125	%
Resulting fair value (per warrant)	$	1.47		$	6.50

Series U Warrants [Member]

Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]

Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions

The Series U warrants will be marked to market as of each balance sheet date until they are exercised or upon expiration, with the changes in fair value recorded as non-operating income or loss in the statement of operations and comprehensive income (loss).

	As of December 31, 2019			As of September 25, 2019
Expected term	4.75 years			5 years
Common stock market price	$	2.40		$	3.42
Risk-free interest rate		1.68	%		1.60	%
Expected volatility		134.5	%		134.9	%
Resulting fair value (per warrant)	$	1.94		$	2.90

Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2019

Summary of Assets and Liabilities Held for Sale and Operating Results Related to Discontinued Operations

Assets and liabilities related to discontinued operations or held for sale as of December 31, 2018 consisted of the following:

	December 31, 2018
Assets
Current assets held for sale:
Accounts receivable, net	$	108
Inventory, net		2,841
Other current assets		328
	$	3,277
Long-term assets held for sale:
Property and equipment, net		260
Other noncurrent assets		1,866
Goodwill		3,550
Intangible assets, net		5,957
		11,633
Total assets	$	14,910

Liabilities
Current liabilities held for sale:
Accounts payable and accrued liabilities	$	580
Long-term liabilities held for sale:
Other noncurrent liabilities		78
Deferred revenues		167
Noncurrent liabilities	$	245
Total liabilities	$	825

The following table summarizes the results of discontinued operations for the periods presented (in thousands).

	Year ended December 31,
	2019			2018
Product revenue	$	901		$	2,671
License revenue		—			1,000
Total revenues		901			3,671
Cost of revenue		857			2,373
Gross profit		44			1,298
Operating expenses:
Research and development		656			3,099
Sales and marketing		411			1,375
General and administrative		185			760
Total operating expenses		1,252			5,234
Operating loss		(1,208	)		(3,936	)
Other income (expense)		112			180
Loss from discontinued operations	$	(1,096	)	$	(3,756	)
Loss from sale of business		(6,508	)		—
Net loss from discontinued operations	$	(7,604	)	$	(3,756	)

Included in the statement of cash flows are the following non-cash adjustments related to the discontinued operations (in thousands):

	For the year ended December 31,
	2019		2018
Depreciation and amortization	$	467	$	1,625
Provision for excess inventory	$	—	$	463
Loss on asset disposal	$	—	$	(36	)

Discontinued Operations Disposed of By Sale [Member]

Summary of Business Consideration to Calculation of the Loss on Sale

The following table summarizes the calculation of the loss on sale of the Cell Therapy business, which was finalized during the fourth quarter of 2019 (in thousands):

Consideration received	$	7,000
Transaction costs		(1,363	)
Net cash proceeds		5,637
Less:
Carrying value of business and assets sold		12,145
Net loss on sale of business	$	(6,508	)

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230

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+ Details

Loss per Share (Tables)

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Schedule of Antidilutive Securities Excluded from Diluted Income (Loss) per Share

The following were excluded from the diluted loss per share calculation for the periods presented because their effect would be anti-dilutive:

	For the Year Ended December 31,
	2019		2018
Outstanding stock options		1,865		3,000
Preferred stock		298,000		95,000
Outstanding warrants		3,637,000		178,000
Total		3,936,865		276,000

Composition of Certain Financial Statement Captions (Tables)

12 Months Ended

Dec. 31, 2019

Composition Of Certain Financial Statement Captions [Abstract]

Other Current Assets

As of December 31, 2019 and 2018, other current assets were comprised of the following (in thousands):

	December 31,
	2019		2018
Prepaid services	$	277	$	166
Prepaid insurance		536		564
Other receivables		144		55
	$	957	$	785

Property and Equipment, net

As of December 31, 2019 and 2018, property and equipment, net, were comprised of the following (in thousands):

	December 31,
	2019			2018
Office and computer equipment	$	1,518		$	1,279
Leasehold improvements		1,682			1,682
		3,200			2,961
Less accumulated depreciation		(1,021	)		(662	)
	$	2,179		$	2,299

Accounts Payable and Accrued Expenses

As of December 31, 2019 and 2018, accounts payable and accrued expenses were comprised of the following (in thousands):

	December 31,
	2019		2018
Accrued expenses	$	791	$	824
Accounts payable		327		721
Accrued payroll and bonus		679		423
Accrued professional fees		332		186
Accrued vacation and compensation		166		192
Accrued R&D studies		858		230
Finance lease obligation - current		120		—
Other current liabilities		6		201
	$	3,279	$	2,777

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Summary of Lease Liabilities and Right-of-Use Assets

The table below summarizes the Company’s lease liabilities and corresponding right-of-use assets (in thousands, except years and rates):

	December 31, 2019
Assets
Operating	$	781
Financing		134
Total leased assets	$	915

Liabilities
Current:
Operating	$	147
Financing		120
Noncurrent:
Operating	$	646
Financing		8
Total lease liabilities	$	921
Weighted-average remaining lease term (years) - operating leases		6.89
Weighted-average remaining lease term (years) - finance leases		1.08
Weighted-average discount rate - operating leases		7.93	%
Weighted-average discount rate - finance leases		5.00	%

Summary of Lease Costs

	Year ended December 31, 2019
Lease expense:
Operating lease expense	$	225
Finance lease expense:
Depreciation of right-of-use assets		116
Interest expense on lease liabilities		9
Total lease expense	$	350

Cash payment information:
Operating cash used for operating leases	$	213
Financing cash used for financing leases		131
Total cash paid for amounts included in the measurement of lease liabilities	$	344

Summary of Future Minimum Annual Lease Payments under Operating and Financing Leases

Total rent expenses for the year ended December 31, 2019 was $0.7 million, which includes leases in the table above, month-to-month operating leases, and common area maintenance charges.

The Company’s future minimum annual lease payments under operating and financing leases at December 31, 2019 are as follows (in thousands):

	Financing Leases			Operating Leases
2020		123			211
2021		7			183
2022		—			123
2023		—			100
Thereafter		—			447
Total minimum lease payments	$	130		$	1,064
Less: amount representing interest		(2	)		(271	)
Present value of obligations under leases		128			793
Less: current portion		(120	)		(147	)
Noncurrent lease obligations	$	8		$	646

Future Payments under Obligation

As of December 31, 2018, future minimum lease payments under the Company’s lease obligations under ASC 840 were as follows:

Years Ending December 31,	Obligation
2019	$	1,282
2020		638
2021		638
2022		192
Total	$	2,750

As of December 31, 2019, the future contractual principal and final fee payments on all of our debt obligations are as follows (as thousands):

Years Ending December 31,
2020	$	5,308
2021		6,180
Total	$	11,488

Term Loan Obligations (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Term Loan Outstanding

Additional details relating to the outstanding Term Loan as of December 31, 2019 and 2018 are presented in the following table (in thousands):

Year ended December 31, 2019

Origination Date

Original

Loan

Amount

Interest

Rate**

Current

Monthly

Payment***

Original

Term

Remaining

Principal

(Face Value)

May 2015

17,700

8.95

48 Months

9,288

Year ended December 31, 2018

Origination Date

Original

Loan

Amount

Interest

Rate**

Current

Monthly

Payment*

Original

Term

Remaining

Principal

(Face Value)

May 2015

17,700

8.95

100

48 Months

12,980

*	Monthly payment as of December 2018, which reflects interest only

**	3 month LIBOR rate with a floor of 1% plus 7.95%

***	Monthly payment as of December 2019, which reflects interest only

Future Payments under Obligation

As of December 31, 2018, future minimum lease payments under the Company’s lease obligations under ASC 840 were as follows:

Years Ending December 31,	Obligation
2019	$	1,282
2020		638
2021		638
2022		192
Total	$	2,750

As of December 31, 2019, the future contractual principal and final fee payments on all of our debt obligations are as follows (as thousands):

Years Ending December 31,
2020	$	5,308
2021		6,180
Total	$	11,488

Face Value to Book Value Reconciliation

Reconciliation of Face Value to Book Value as of December 31, 2019
Total debt obligations, including final payment fee (Face Value)	$	11,488
Less: Debt discount		(428	)
Total obligation	$	11,060

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 835
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Components of Income/(Loss) Before Income Tax Provision (Benefit)

The components of income/(loss) from continuing operations before income tax provision (benefit) as of December 31, 2019 and 2018 are as follows (in thousands):

	2019			2018
U.S.	$	(3,439	)	$	(8,346	)
Foreign		403			(507	)
	$	(3,036	)	$	(8,853	)

Reconciliation of Total Income Tax Provision

A reconciliation of the total income tax provision tax rate to the statutory federal income tax rates of 21% for the years ended December 31, 2019 and 2018, respectively, is as follows:

	2019			2018
Income tax expense (benefit) at federal statutory rate		(21.0	)%		(21.0	)%
Income tax expense (benefit) at state statutory rate		(12.2	)%		(6.1	)%
Change in valuation allowance		23.0	%		34.8	%
Change in state rate		(1.3	)%		(0.1	)%
Permanent interest adjustments		1.1	%		0.7	%
Stock compensation		13.7	%		1.8	%
Research credit		(1.8	)%		(1.4	)%
Return to provision		3.1	%		(3.4	)%
NOLs expiring and adjustments to NOL		19.2	%		—
Mark to market adjustment		(24.0	)%		(5.3	)%
Other, net		0.2	%		—
		0.0	%		(0.0	)%

Deferred Tax Assets and Liabilities

The tax effects of temporary differences that give rise to significant portions of our deferred tax assets and deferred tax liabilities as of December 31, 2019 and 2018 are as follows (in thousands):

	2019			2018
Deferred tax assets:
Allowances and reserves	$	6		$	270
Accrued expenses		283			122
Stock based compensation		657			996
Net operating loss carryforwards		92,659			91,197
Income tax credit carryforwards		8,749			8,671
Property and equipment, principally due to differences in depreciation		95			548
Intangible assets		370
Other, net		217			38
		103,036			101,842
Valuation allowance		(102,822	)		(101,091	)
Total deferred tax assets, net of allowance		214			751
Deferred tax liabilities:
Other		(214	)		(751	)
Total deferred tax liability		(214	)		(751	)
Net deferred tax assets (liability)	$	—		$	—

Unrecognized Tax Benefits Activity

Following is a tabular reconciliation of the unrecognized tax benefits activity during the years ended December 31, 2019 and 2018 (in thousands):

	2019			2018
Unrecognized Tax Benefits – Beginning	$	2,216		$	2,157
Gross increases – tax positions in prior period		—			1
Gross decreases – tax positions in prior period		(18	)		(3	)
Gross increase – current-period tax positions		36			61
Unrecognized Tax Benefits – Ending	$	2,234		$	2,216

Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Activity

A summary of activity for the year ended December 31, 2019 and December 31, 2018 is as follows:

	Options			Weighted Average Exercise Price
Balance as of December 31, 2018		2,752		$	4,003.50
Granted		2,800		$	15.69
Expired		(37	)	$	41,692.00
Cancelled/forfeited		(3,650	)	$	1,089.35
Balance as of December 31, 2019		1,865		$	2,968.22

Stock Options Vested and Expected to Vest

	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Balance as of December 31, 2019		1,865	$	2,968.22		7.20	$	-
Vested and expected to vest at December 31, 2019		1,658	$	3,286.28		7.10	$	-
Exercisable at December 31, 2019		1,133	$	4,729.07		6.50	$	-

Weighted-average Assumptions

	Years ended December 31,
	2019			2018
Expected term	7.0 years			7.1 years
Risk-free interest rate		2.41	%		2.94	%
Volatility		96.52	%		92.87	%
Dividends		—			—
Resulting weighted average grant date fair value	$	0.26		$	1.74

Compensation Cost Recognized for Stock Options

Years ended December 31,

2019

2018

Total compensation cost for share-based payment

arrangements recognized in the statement of

operations (net of tax of $0)

127

355

Organization and Operations - Additional Information (Details)									1 Months Ended		3 Months Ended	12 Months Ended
	Aug. 05, 2019 $ / shares shares	Apr. 25, 2019 USD ($)	Apr. 24, 2019 USD ($)	Sep. 21, 2018 USD ($)	Aug. 28, 2018 $ / shares	Jul. 25, 2018 USD ($) shares	Jun. 01, 2018 USD ($)	May 23, 2018 $ / shares shares	Sep. 30, 2019 $ / shares shares	Aug. 31, 2019 $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) Subsidiary $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Aug. 16, 2019 shares	Aug. 06, 2019 shares	Jun. 30, 2019 USD ($)	May 24, 2018 shares	Dec. 31, 2017 USD ($) shares
Basis Of Presentation And New Accounting Standards [Line Items]
Number of wholly-owned subsidiaries \| Subsidiary												5
Proceeds from sale of business \| $												$ 5,637,000	$ 0
Reverse stock split of common stock	0.02							0.1
Common stock, par value (in dollars per share) \| $ / shares	$ 0.001							$ 0.001			$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)								75,000,000			100,000,000	100,000,000	100,000,000				100,000,000
Common stock, shares issued (in shares)								61,600,000			296,609	3,880,588	296,609				6,200,000
Common stock, shares outstanding (in shares)								61,600,000			296,609	3,880,588	296,609				6,200,000
Number of shares callable by warrants (in shares)								23,400,000									2,300,000
Preferred stock, shares authorized (in shares)	5,000,000							5,000,000			5,000,000	5,000,000	5,000,000		5,000,000		5,000,000
Common stock, reverse stock split, fractional shares issued	0							0
Reverse stock split effective date for trading purposes	Aug. 06, 2019
Reverse stock split of common stock description												Upon effectiveness, each 50 shares of issued and outstanding common stock were converted into one newly issued and outstanding share of common stock.
Net loss \| $												$ 10,887,000	$ 12,634,000
Accumulated deficit \| $											$ (414,383,000)	(425,270,000)	(414,383,000)
Net cash used in operating activities \| $												$ (5,906,000)	(11,975,000)
Substantial doubt about going concern, description												These factors raise substantial doubt about the Company’s ability to continue as a going concern
Reimbursement revenue recognized \| $												$ 4,600,000
Option vesting period												4 years
Option granted												2,800
Common stock issued, value \| $												$ 2,208,000	1,624,000
Proceeds from sale of common stock, net \| $												15,964,000	0
Proceeds from issuance warrants \| $						$ 5,700,000
Stockholders' equity (deficit) \| $											$ 5,225,000	$ 1,160,000	$ 5,225,000					$ 13,000,000
Nasdaq Stock Market LLC [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Reverse stock split of common stock										0.02
Number of consecutive business days no longer able to meet the required closing bid price of common stock					30 days
Minimum bid price of common stock required for Nasdaq listing rule \| $ / shares					$ 1.00					$ 1.00
Grace period provided with minimum bid price for Nasdaq listing rule					180 days
Grace date for minimum bid price requirement for Nasdaq listing					Feb. 25, 2019
Common stock minimum bid price required to regain compliance \| $ / shares					$ 1.00
Number of consecutive business days required to regain compliance					10 days
Date to regain compliance after meeting continued listing requirement					Aug. 26, 2019
Additional grace period provided with minimum bid price to regain compliance					180 days
Description of compliance with minimum bid price requirement												The Company was granted an additional compliance period of 180 calendar days, or until August 26, 2019, in which to regain compliance after meeting the continued listing requirement for market value of publicly held shares and all other initial listing standards for the Nasdaq Capital Market, with the exception of the bid price requirement, and providing notice to Nasdaq staff of our intent to cure the deficiency during this second compliance period, by effecting a reverse stock split, if necessary.
Shares, Outstanding										786,807
Stockholders' equity (deficit) \| $												$ (1,200,000)				$ 6,300,000
Minimum stockholders equity requirement \| $												$ 2,500,000
Minimum shares requirement for continued listing														500,000
Series U Warrants [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock issued (in shares)												3,450,000
Sale of Stock, Price Per Share \| $ / shares												$ 5.00
Representative Warrants [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of shares callable by warrants (in shares)												75,000
Warrant exercise price (in dollars per share) \| $ / shares												$ 6.25
Common Stock [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock, shares outstanding (in shares)											296,609	3,880,588	296,609					115,651
Common stock issued (in shares)						6,723						184,666	92,169
Warrant exercised												65,114
Stockholders' equity (deficit) \| $												$ 4,000
Common Stock [Member] \| Lincoln Park [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock issued (in shares)											12,802	32,170
Common stock issued, value \| $				$ 5,000,000
Period exercisable from the date of issuance				24 months
Proceeds from sale of common stock, net \| $											$ 300,000	$ 300,000
Common Stock [Member] \| B. Riley FBR [Member] \| Sales Agreement [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Remaining availability under financing facility \| $							$ 0
Common Stock [Member] \| Maximum [Member] \| B. Riley FBR [Member] \| Sales Agreement [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Proceeds from sale of common stock, net \| $							$ 6,500,000
Common Class A [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock issued (in shares)												289,000
Common Class B [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of shares callable by warrants (in shares)												2,711,000
Series C Convertible Preferred Stock [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Preferred stock, shares authorized (in shares)						7,000
Common stock issued (in shares)						6,723
Common stock issued, value \| $													$ 3,041,000
Underwriter [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Underwritten public offering description									pursuant to which the Company sold in an underwritten public offering an aggregate of (i) 289,000 Class A Units, each consisting of one share of common stock, par value $0.001 per share, of the Company and one Series U warrant to purchase one share of common stock, and (ii) 2,711,000 Class B Units, each consisting of one pre-funded Series V warrant to purchase one share of common stock and one Series U Warrant to purchase one share of common stock at a public offering price of $5.00 per Class A Unit and $4.9999 per Class B Unit (“September 2019 Offering”). In addition, the Company granted the Underwriters a 45-day option to purchase up to an additional 450,000 shares of the Company’s common stock and/or Series U Warrants at the public offering price, less the underwriting discounts and commissions. The Underwriters exercised their option to purchase an additional 450,000 Series U warrants. The Company also issued to the Representative warrants (in the form of the Series U warrants) to purchase 75,000 shares of common stock with an exercise price of $6.25 per share of common stock (“Representative Warrants”).
Option vesting period									45 days
Warrant granted									450,000
Underwriter [Member] \| Maximum [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Option granted									450,000
Underwriter [Member] \| Series U Warrants [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Warrant exercised									450,000
Underwriter [Member] \| Representative Warrants [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of shares callable by warrants (in shares)									75,000
Warrant exercise price (in dollars per share) \| $ / shares									$ 6.25
Underwriter [Member] \| Common Class A [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock, par value (in dollars per share) \| $ / shares									$ 0.001
Common stock issued (in shares)									289,000
Underwriter [Member] \| Common Class A [Member] \| Series U Warrants [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Sale of Stock, Price Per Share \| $ / shares									$ 5.00
Underwriter [Member] \| Common Class B [Member] \| Series V Warrants
Basis Of Presentation And New Accounting Standards [Line Items]
Number of shares callable by warrants (in shares)									2,711,000
Underwriter [Member] \| Common Class B [Member] \| Series U Warrants [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Sale of Stock, Price Per Share \| $ / shares									$ 4.9999
2014 Equity Incentive Plan [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of shares callable by warrants (in shares)								9,100,000									900,000
Sale of UK Subsidiary and Certain Assets [Member] \| Loan and Security Agreement [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Proceeds from sale of business \| $			$ 4,000,000
Payments for principal, interest and fees \| $			1,700,000
Sale of the Japanese Subsidiary and Certain Assets [Member] \| Loan and Security Agreement [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Proceeds from sale of business \| $		$ 3,000,000
Payments for principal, interest and fees \| $		1,400,000
UK Subsidiary and Cell Therapy Assets [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Proceeds from sale of business \| $			3,300,000
UK Subsidiary and Cell Therapy Assets [Member] \| Amendment To Loan And Security Agreement
Basis Of Presentation And New Accounting Standards [Line Items]
Payments for principal, interest and fees \| $			$ 1,700,000
Japanese Subsidiary and Cell Therapy Assets [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Proceeds from sale of business \| $		2,400,000
Japanese Subsidiary and Cell Therapy Assets [Member] \| Amendment To Loan And Security Agreement
Basis Of Presentation And New Accounting Standards [Line Items]
Payments for principal, interest and fees \| $		$ 1,400,000

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) ReportableUnit Segment	Dec. 31, 2018 USD ($) Segment
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents investments with original maturities	$ 0	$ 0
Impairment loss	0	0
Impairment charges	$ 0
Number of reporting units \| ReportableUnit	1
Qualifying expenditures related to research	$ 1,500,000	2,700,000
Interest or penalties related to income tax matters	$ 0	$ 0
Number of operating segment \| Segment	1	1
Operating lease right-use-of assets	$ 781,000
Operating lease, liability	793,000
BARDA Contract [Member] \| Development [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized	$ 7,000,000	$ 3,000,000
Customer Concentration Risk [Member] \| Revenue Recognized [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	100.00%
Customer Concentration Risk [Member] \| Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	100.00%	100.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives of the assets	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful lives of the assets	5 years
Letter of Credit [Member]
Summary Of Significant Accounting Policies [Line Items]
Letters of credit amount pursuant to lease agreement	$ 40,000	$ 40,000

Summary of Significant Accounting Policies - Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions (Details)	Dec. 31, 2019 $ / shares	Dec. 31, 2018 $ / shares
Expected Term [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants expected term	1 year 1 month 6 days	2 years 1 month 6 days
Common Stock Market Price [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	2.40	14.50
Risk-free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	0.0159	0.0248
Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	1.68	1.25
Resulting Fair Value (Per Warrant) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	1.47	6.50

Fair Value - Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions (Details)	Dec. 31, 2019 $ / shares	Sep. 25, 2019 $ / shares	Dec. 31, 2018 $ / shares
Series U Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants expected term	5 years
Expected Term [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants expected term	1 year 1 month 6 days		2 years 1 month 6 days
Common Stock Market Price [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	2.40		14.50
Risk-free Interest Rate [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	0.0159		0.0248
Expected Volatility [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	1.68		1.25
Resulting Fair Value (Per Warrant) [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	1.47		6.50
Level 3 [Member] \| Expected Term [Member] \| Series T Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants expected term	1 year 1 month 6 days		2 years 1 month 6 days
Level 3 [Member] \| Expected Term [Member] \| Series U Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants expected term	4 years 9 months	5 years
Level 3 [Member] \| Common Stock Market Price [Member] \| Series T Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	2.40		14.50
Level 3 [Member] \| Common Stock Market Price [Member] \| Series U Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	2.40	3.42
Level 3 [Member] \| Risk-free Interest Rate [Member] \| Series T Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	0.0159		0.0248
Level 3 [Member] \| Risk-free Interest Rate [Member] \| Series U Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	0.0168	0.0160
Level 3 [Member] \| Expected Volatility [Member] \| Series T Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	1.68		1.25
Level 3 [Member] \| Expected Volatility [Member] \| Series U Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	1.345	1.349
Level 3 [Member] \| Resulting Fair Value (Per Warrant) [Member] \| Series T Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	1.47		6.50
Level 3 [Member] \| Resulting Fair Value (Per Warrant) [Member] \| Series U Warrants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants measurement input	1.94	2.90

Fair Value - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt discount	$ 0.4	$ 0.6
2018 Rights Offering [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Redemption price of warrant prior to expiration	$ 0.01
Common stock price per share for warrant redemption	$ 3.63
Number of consecutive trading days for warrant redemption	20 years
Warrants liability fair value	$ 0.1	$ 3.1

Fair Value - Summary of Change in Level 3 Warrant Liability Value (Details) - Warrant Liability [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Warrant liability
Beginning balance	$ 916	$ 3,148
Issuance of warrants	10,214
Exercises	(794)
Change in fair value	(3,407)	(2,233)
Ending balance	$ 6,929	$ 916

Fair Value - Fair Value and Carrying Value of Term Loan (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt	$ 10,761	$ 14,043
Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt	$ 11,060	$ 14,202

Discontinued Operations - Summary of Business Consideration to Calculation of the Loss on Sale (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 25, 2019	Dec. 31, 2019	Dec. 31, 2018
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net cash proceeds		$ 5,637	$ 0
Net loss on sale of business		$ (6,508)	$ (36)
Discontinued Operations Disposed of By Sale [Member] \| Cell Therapy Business [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Consideration received	$ 7,000
Transaction costs	(1,363)
Net cash proceeds	5,637
Carrying value of business and assets sold	12,145
Net loss on sale of business	$ (6,508)

Discontinued Operations - Additional Information (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Discontinued Operations And Disposal Groups [Abstract]
Assets Related to Discontinued Operation	$ 0
Liabilities Related to Discontinued Operation	$ 0

Discontinued Operations - Summary of Assets and Liabilities Related to Discontinued Operation Held for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets held for sale:
Total current assets		$ 3,277
Long-term assets held for sale:
Total non current assets		11,633
Total assets	$ 0
Long-term liabilities held for sale:
Noncurrent liabilities		245
Total liabilities	$ 0
Held for Sale [Member]
Current assets held for sale:
Accounts receivable, net		108
Inventory, net		2,841
Other current assets		328
Total current assets		3,277
Long-term assets held for sale:
Property and equipment, net		260
Other noncurrent assets		1,866
Goodwill		3,550
Intangible assets, net		5,957
Total non current assets		11,633
Total assets		14,910
Current liabilities held for sale:
Accounts payable and accrued liabilities		580
Long-term liabilities held for sale:
Other noncurrent liabilities		78
Deferred revenues		167
Noncurrent liabilities		245
Total liabilities		$ 825

Discontinued Operations - Summary of Operating Results Related to Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total revenues	$ 901	$ 3,671
Cost of revenue	857	2,373
Gross profit	44	1,298
Operating expenses:
Research and development	656	3,099
Sales and marketing	411	1,375
General and administrative	185	760
Total operating expenses	1,252	5,234
Operating loss	(1,208)	(3,936)
Other income (expense)	112	180
Loss from discontinued operations	(1,096)	(3,756)
Loss from sale of business	(6,508)	(36)
Net loss from discontinued operations	(7,604)	(3,756)
Product revenue [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total revenues	$ 901	2,671
License revenue [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Total revenues		$ 1,000

Discontinued Operations - Summary of Non-Cash Adjustments Related to Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Noncash Investing and Financing Items [Abstract]
Depreciation and amortization	$ 467	$ 1,625
Provision for excess inventory	0	463
Loss on asset disposal	$ (6,508)	$ (36)

Loss per Share (Details) - Series C Convertible Preferred Stock [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Aug. 02, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Preferred stock conversion price (in dollars per share)	$ 39.93
Preferred stock conversion price reduced (in dollars per share)	$ 7.50
Dividend Paid [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Dividends payable	$ 554,000	$ 554,000	$ 2,500,000

Loss per Share - Schedule of Antidilutive Securities Excluded from Diluted Income (Loss) per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Dilutive common shares excluded from the calculations of diluted loss per share (in shares)	3,936,865	276,000
Outstanding Stock Options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Dilutive common shares excluded from the calculations of diluted loss per share (in shares)	1,865	3,000
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Dilutive common shares excluded from the calculations of diluted loss per share (in shares)	298,000	95,000
Outstanding Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Dilutive common shares excluded from the calculations of diluted loss per share (in shares)	3,637,000	178,000

Composition of Certain Financial Statement Captions - Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Other Current Assets [Abstract]
Prepaid services	$ 277	$ 166
Prepaid insurance	536	564
Other receivables	144	55
Total other current assets	$ 957	$ 785

Composition of Certain Financial Statement Captions - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property and Equipment, net [Abstract]
Office and computer equipment	$ 1,518	$ 1,279
Leasehold improvements	1,682	1,682
Property and equipment, gross	3,200	2,961
Less accumulated depreciation	(1,021)	(662)
Property and equipment, net	$ 2,179	$ 2,299

Composition of Certain Financial Statement Captions - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Composition Of Certain Financial Statement Captions [Abstract]
Depreciation expense	$ 0.4	$ 0.3

Composition of Certain Financial Statement Captions - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts Payable and Accrued Expenses [Abstract]
Accrued expenses	$ 791	$ 824
Accounts payable	327	721
Accrued payroll and bonus	679	423
Accrued professional fees	332	186
Accrued vacation and compensation	166	192
Accrued R&D studies	858	230
Finance lease obligation - current	120
Other current liabilities	6	201
Accounts payable and accrued expenses, Total	$ 3,279	$ 2,777

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands			12 Months Ended
	Jul. 25, 2019	Feb. 27, 2018	Dec. 31, 2019	Dec. 31, 2018
Recorded Unconditional Purchase Obligation [Line Items]
Restricted cash			$ 40
Initial term of lease			63 months
Buy-out of obligations lease		$ 600
Contractual obligation			$ 11,488	$ 2,750
Cell Therapy Business [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Sale of business month and year	2019-04
Cell Therapy Business [Member] \| Tap Advisors LLC [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Payments for legal settlements			700
Cell Therapy Business [Member] \| Tap Advisors LLC [Member] \| Pending Litigation [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Loss contingency damages sought value	$ 3,700
Operating Lease Obligations [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Rent expense				$ 1,900
Pre-clinical Research Study Obligations [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Contractual obligation			$ 900
San Antonio, Texas [Member] \| Office Laboratory and Storage Space [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating leases expiry year			2028

Commitments and Contingencies - Summary of Lease Liabilities and Right-of-Use Assets (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Assets
Operating	$ 781
Financing	134
Total leased assets	915
Liabilities
Operating lease liabilities, current	147
Financing lease liabilities, current	120
Operating lease liabilities. noncurrent	646
Financing lease liabilities, noncurrent	8
Total lease liabilities	$ 921
Weighted-average remaining lease term (years) - operating leases	6 years 10 months 20 days
Weighted-average remaining lease term (years) - finance leases	1 year 29 days
Weighted-average discount rate - operating leases	7.93%
Weighted-average discount rate - finance leases	5.00%

Commitments and Contingencies - Summary of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Lease expense:
Operating lease expense	$ 225
Finance lease expense:
Depreciation of right-of-use assets	116
Interest expense on lease liabilities	9
Total lease expense	350
Cash payment information:
Operating cash used for operating leases	213
Financing cash used for financing leases	131	$ 0
Total cash paid for amounts included in the measurement of lease liabilities	$ 344

Commitments and Contingencies - Summary of Future Minimum Annual Lease Payments under Operating and Financing Leases (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Financing Leases
2020	$ 123
2021	7
Total minimum lease payments	130
Less: amount representing interest	(2)
Present value of obligations under leases	128
Less: current portion	(120)
Financing lease liabilities, noncurrent	8
Operating Leases
2020	211
2021	183
2022	123
2023	100
Thereafter	447
Total minimum lease payments	1,064
Less: amount representing interest	(271)
Present value of obligations under leases	793
Less: current portion	(147)
Noncurrent operating lease liability	$ 646

Commitments and Contingencies - Future Payments under Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
2019	$ 5,308	$ 1,282
2020	6,180	638
2021		638
2022		192
Total	$ 11,488	$ 2,750

Term Loan Obligations (Details) - USD ($)				1 Months Ended		12 Months Ended
Term Loan Obligations (Details) - USD ($)	Dec. 31, 2018	Aug. 31, 2018	May 29, 2015	Jun. 30, 2018	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	May 24, 2018	May 23, 2018	Sep. 20, 2017
Debt Instrument [Line Items]
Number of shares callable by warrants (in shares)								2,300,000	23,400,000
Interest expense						$ 1,855,000	$ 1,922,000
Non-cash amortization						$ 500,000	$ 600,000
LIBOR [Member] \| Interest Rate Floor [Member]
Debt Instrument [Line Items]
Basis variable rate			1.00%
Term Loan [Member]
Debt Instrument [Line Items]
Origination Date						May 29, 2015	May 29, 2015
Original Loan Amount	$ 17,700,000		$ 17,700,000			$ 17,700,000	$ 17,700,000
Basis variable rate			7.95%
Maturity date	Jun. 01, 2020		Jun. 01, 2019			Jun. 01, 2021
Fees amount associated with loan			$ 1,100,000
Number of shares callable by warrants (in shares)			188
Warrant exercise price (in dollars per share)			$ 5,175
Date from which warrants are exercisable						Nov. 30, 2015
Warrant expiration date						May 29, 2025
Amendment fee	$ 350,000	$ 50,000		$ 250,000	$ 250,000
Extended interest-only period		Dec. 31, 2018
Percentage of proceeds received		75.00%
Debt instrument, interest-only period	The Amendment also requires that the Company achieve one of the following by January 31, 2019: enter into an asset sale agreement with a minimum unrestricted net cash proceeds to the Company of $4.0 million; enter into a binding agreement for the issuance and sale of its equity securities or unsecured convertible subordinated debt which would result in unrestricted gross cash proceeds of not less than $7.5 million; or enter into a merger agreement pursuant to which the obligations under the Loan Agreement would be paid down to a level satisfactory to Oxford.	The Third Amendment extends the interest-only period under the Term Loan to December 31, 2018 and also requires that the Company pay to Oxford, in accordance with its pro rata share of the loans, 75% of all proceeds received (i) from the issuance and sale of unsecured subordinated convertible debt, (ii) in connection with a joint venture, collaboration or other partnering transaction, (iii) in connection with any licenses, (iv) from dividends (other than non-cash dividends from wholly owned subsidiaries) and (v) from the sale of any assets (such requirement, the “Prepayment Requirement”).
Minimum amount to be paid pursuant prepayment requirement		$ 7,000,000
Debt instrument prepayment, description		The Prepayment Requirement does not apply to proceeds from the sale and issuance of the Company’s equity securities, other than convertible debt. The Prepayment Requirement shall apply until an aggregate principle amount of $7.0 million has been paid pursuant to the Prepayment Requirement. However, if less than $7.0 million has been paid pursuant to the Prepayment Requirement on December 31, 2018 then the Company is required to promptly make additional payments until an aggregate principal amount of $7.0 million has been paid.
Minimum liquidity covenant	$ 2,000,000						$ 2,000,000			$ 1,500,000
Debt instrument, covenant compliance						we were in compliance with all of the debt covenants under the Loan and Security Agreement
Minimum [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Interest rate			8.95%
Net proceeds excess receives from unrestricted cash	4,000,000
Unrestricted gross cash proceeds required to extend interest-only period	$ 7,500,000
Maximum [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Original Loan Amount						$ 3,000,000

Term Loan Obligations - Term Loan Outstanding (Details) - Term Loan [Member] - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

May 29, 2015

Additional details relating term loan that is outstanding [Abstract]

Origination Date

May 29, 2015

Original Loan Amount

$ 17,700

Interest Rate

^[1]

8.95%

Current Monthly Payment

$ 72

^[2]

$ 100

^[3]

Original Term

48 months

Remaining Principal (Face Value)

$ 9,288

$ 12,980

[1]	3 month LIBOR rate with a floor of 1% plus 7.95%
[2]	Monthly payment as of December 2019, which reflects interest only
[3]	Monthly payment as of December 2018, which reflects interest only

Term Loan Obligations - Future Payments under Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Future contractual principal and final fee payments on all debt [Abstract]
2020	$ 5,308	$ 1,282
2021	6,180	638
Total	$ 11,488	$ 2,750

Term Loan Obligations - Face Value to Book Value Reconciliation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Face Value to Book Value [Abstract]
Total debt obligations, including final payment fee (Face Value)	$ 11,488	$ 2,750
Less: Debt discount	(428)
Total obligation	$ 11,060

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Provision or benefit for income taxes	$ 0	$ 0
Income Tax Contingency [Abstract]
Valuation allowance	102,822,000	101,091,000
Increase (decrease) in valuation allowance	$ 1,700,000
Net operating loss carryforwards, Expire date	begin to expire in 2020 and 2028
State tax credit carryforwards	$ 5,500,000
Cumulative change in ownership	50.00%
Period of net operating loss and R&D tax credit carry forwards to offset future taxable income	3 years
Liability for uncertain tax positions	$ 0	$ 0
Period for material changes of liability for uncertain tax benefits	12 months
Interest related to unrecognized tax benefits in interest expense and penalties	$ 0
Federal [Member]
Income Tax Contingency [Abstract]
Tax loss carryforwards	386,800,000
Federal tax carry forward	$ 6,400,000
Federal tax credit carryforward, Expiration date	begin to expire in 2020
Net operating losses	$ 21,900,000
Federal [Member] \| Maximum [Member]
Income Tax Contingency [Abstract]
Percentage of federal net operating losses used to offset of future taxable income	80.00%
State [Member]
Income Tax Contingency [Abstract]
Tax loss carryforwards	$ 161,900,000

Income Taxes - Components of Income/(Loss) Before Income Tax Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S.	$ (3,439)	$ (8,346)
Foreign	403	(507)
Income/(loss) before income tax provision (benefit)	$ (3,036)	$ (8,853)

Income Taxes - Reconciliation of Total Income Tax Provision (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the total income tax provision tax rate [Abstract]
Income tax expense (benefit) at federal statutory rate	(21.00%)	(21.00%)
Income tax expense (benefit) at state statutory rate	(12.20%)	(6.10%)
Change in valuation allowance	23.00%	34.80%
Change in state rate	(1.30%)	(0.10%)
Permanent interest adjustments	1.10%	0.70%
Stock compensation	13.70%	1.80%
Research credit	(1.80%)	(1.40%)
Return to provision	3.10%	(3.40%)
NOLs expiring and adjustments to NOL	19.20%
Mark to market adjustment	(24.00%)	(5.30%)
Other, net	0.20%
Total income tax provision	0.00%	0.00%

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets [Abstract]
Allowances and reserves	$ 6	$ 270
Accrued expenses	283	122
Stock based compensation	657	996
Net operating loss carryforwards	92,659	91,197
Income tax credit carryforwards	8,749	8,671
Property and equipment, principally due to differences in depreciation	95	548
Intangible assets	370
Other, net	217	38
Deferred tax assets (Total)	103,036	101,842
Valuation allowance	(102,822)	(101,091)
Total deferred tax assets, net of allowance	214	751
Deferred tax liabilities [Abstract]
Other	(214)	(751)
Total deferred tax liability	(214)	(751)
Net deferred tax assets (liability)	$ 0	$ 0

Income Taxes - Unrecognized Tax Benefits Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule of reconciliation of unrecognized tax benefits activity [Roll Forward]
Unrecognized Tax Benefits – Beginning	$ 2,216	$ 2,157
Gross increases – tax positions in prior period	0	1
Gross decreases – tax positions in prior period	(18)	(3)
Gross increase – current-period tax positions	36	61
Unrecognized Tax Benefits – Ending	$ 2,234	$ 2,216

Employee Benefit Plan (Details) - USD ($)	12 Months Ended
Employee Benefit Plan (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Discretionary or matching contributions	$ 0	$ 0

Stockholders' Equity - Preferred Stock (Details) - USD ($)					12 Months Ended
	Sep. 25, 2019	Aug. 02, 2019	Jul. 25, 2018	Jul. 17, 2018	Dec. 31, 2019	Dec. 31, 2018	Aug. 06, 2019	Aug. 05, 2019	May 24, 2018	May 23, 2018
Preferred Stock [Abstract]
Preferred stock, shares authorized (in shares)					5,000,000	5,000,000	5,000,000	5,000,000	5,000,000	5,000,000
Preferred stock, par value (in dollars per share)					$ 0.001	$ 0.001
Preferred stock, shares outstanding (in shares)					1,959	4,606
Number of shares callable by warrants (in shares)									2,300,000	23,400,000
2018 Rights Offering [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)	1			1
Common stock issued (in shares)			6,723
Gross proceeds from private placement of stock			$ 5,700,000
2018 Rights Offering [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)				1,050
Warrant exercise price (in dollars per share)				$ 1,000
Series A Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares outstanding (in shares)					0	0
Convertible preferred stock					3.60%	3.60%
Series B Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares outstanding (in shares)					1,021	1,112
Series C Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares authorized (in shares)			7,000
Preferred stock, par value (in dollars per share)			$ 0.001
Preferred stock, shares outstanding (in shares)					938	3,494
Common stock issued (in shares)			6,723
Preferred stock conversion price (in dollars per share)					$ 39.93
Preferred stock conversion price reduced (in dollars per share)					$ 7.50
Series C Convertible Preferred Stock [Member] \| Dividend Paid [Member]
Preferred Stock [Abstract]
Dividends payable		$ 554,000			$ 554,000	$ 2,500,000
Series C Convertible Preferred Stock [Member] \| 2018 Rights Offering [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)				20,000
Preferred stock conversion price (in dollars per share)	$ 7.50	$ 39.93
Preferred stock conversion price reduced (in dollars per share)	3.2132	$ 7.50
Common Stock and Series B Convertible Preferred Stock [Member] \| 2018 Rights Offering [Member]
Preferred Stock [Abstract]
Charge on Non Transferable Subscription Rights				$ 0
Series T Warrants [Member] \| 2018 Rights Offering [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)		1
Warrant exercise price (in dollars per share)		$ 0.7986
Warrant exercise price reduced (in dollars per share)		$ 0.15
Series T Warrants [Member] \| 2018 Rights Offering [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)		50
Warrant exercise price (in dollars per share)	$ 3.2132
50 Series T Warrants [Member] \| 2018 Rights Offering [Member]
Preferred Stock [Abstract]
Warrant exercise price (in dollars per share)		$ 7.50
2018 Rights Offering [Member] \| Series T Warrants [Member] \| Outstanding Warrants [Member]
Preferred Stock [Abstract]
Class of warrant outstanding					3,788,400
Number of warrants exercised					75,768
2018 Rights Offering [Member] \| Series C Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares outstanding (in shares)					938
Number of preferred stock, shares exercised					291,920

Stockholders' Equity - Common Stock (Details) - USD ($)				3 Months Ended	7 Months Ended	12 Months Ended
Stockholders' Equity - Common Stock (Details) - USD ($)	Sep. 21, 2018	Jul. 25, 2018	Jun. 01, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	May 24, 2018	May 23, 2018
Common Stock [Abstract]
Number of shares callable by warrants (in shares)								2,300,000	23,400,000
Proceeds from sale of common stock, net						$ 15,964,000	$ 0
Common stock issued, value						$ 2,208,000	$ 1,624,000
Series U Warrants [Member]
Common Stock [Abstract]
Common stock issued (in shares)						3,450,000
Sale of Stock, Price Per Share						$ 5.00
Warrants expected term						5 years
Representative Warrants [Member]
Common Stock [Abstract]
Number of shares callable by warrants (in shares)						75,000
Warrant exercise price (in dollars per share)						$ 6.25
Common Stock [Member]
Common Stock [Abstract]
Common stock issued (in shares)		6,723				184,666	92,169
Warrants expected term						5 years
Common Stock [Member] \| B. Riley FBR [Member] \| Sales Agreement [Member] \| Maximum [Member]
Common Stock [Abstract]
Proceeds from sale of common stock, net			$ 6,500,000
Common Stock [Member] \| B. Riley FBR [Member] \| ATM Program [Member] \| Sales Agreement [Member]
Common Stock [Abstract]
Common stock issued (in shares)					79,234
Proceeds from sale of common stock, net					$ 1,700,000
Common Stock [Member] \| B. Riley FBR [Member] \| ATM Program [Member] \| Sales Agreement [Member] \| Maximum [Member]
Common Stock [Abstract]
Proceeds from sale of common stock, net			$ 6,500,000
Common Stock [Member] \| Lincoln Park Capital Fund, LLC [Member]
Common Stock [Abstract]
Common stock issued (in shares)						32,170
Proceeds from sale of common stock, net						$ 300,000
Common stock issued, value	$ 5,000,000
Period exercisable from the date of issuance	24 months
Common Stock [Member] \| Lincoln Park Capital Fund, LLC [Member] \| Purchase Agreement [Member]
Common Stock [Abstract]
Common stock issued (in shares)				12,802
Proceeds from sale of common stock, net				$ 300,000
Common Class A [Member]
Common Stock [Abstract]
Common stock issued (in shares)						289,000
Common Class B [Member]
Common Stock [Abstract]
Number of shares callable by warrants (in shares)						2,711,000

Stock-based Compensation - Additional Information (Details) - USD ($)		1 Months Ended						12 Months Ended
	Dec. 29, 2015	May 31, 2018	May 31, 2017	Jan. 31, 2017	May 31, 2016	Aug. 31, 2015	Aug. 31, 2014	Dec. 31, 2019	Dec. 31, 2018	Feb. 29, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Securities remaining and available for future issuances (in shares)								97,866
Stock Option Activity [Abstract]
Stock option vesting period								4 years
Stock option contractual term								10 years
Stock option vesting provisions								12/48 of a granted award will vest after one year of service, while an additional 1/48 of the award will vest at the end of each month thereafter for 36 months, or 1/48 of the award will vest at the end of each month over a four-year period.
Weighted Average Remaining Contractual Terms [Abstract]
Stock options exercised								$ 0	$ 0
Dividend yield assumed								0
Total unamortized compensation cost related to outstanding unvested stock options and restricted stock awards								$ 58,000
Weighted average period for recognition of cost								1 year 4 months 20 days
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares to be issued (in shares)		15,000	4,000		666	603	530	80,000
Securities remaining and available for future issuances (in shares)								99,699
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares to be issued (in shares)	133			500
Securities remaining and available for future issuances (in shares)								30
2015 Plan [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increased in the total number of shares of common stock reserved for issuance										250,000

Stock-based Compensation - Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Options [Roll Forward]
Balance as of December 31, 2018 (in shares) \| shares	2,752
Granted (in shares) \| shares	2,800
Expired (in shares) \| shares	(37)
Cancelled/forfeited (in shares) \| shares	(3,650)
Balance as of December 31, 2019 (in shares) \| shares	1,865
Weighted Average Exercise Price [Roll Forward]
Balance as of December 31, 2018 (in dollars per share) \| $ / shares	$ 4,003.50
Granted (in dollars per share) \| $ / shares	15.69
Expired (in dollars per share) \| $ / shares	41,692.00
Cancelled/forfeited (in dollars per share) \| $ / shares	1,089.35
Balance as of December 31, 2019 (in dollars per share) \| $ / shares	$ 2,968.22

Stock-based Compensation - Stock Options Vested and Expected to Vest (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Options [Roll Forward]
Balance as of December 31, 2019	1,865	2,752
Vested and expected to vest at December 31, 2019	1,658
Exercisable at December 31, 2019	1,133
Weighted Average Exercise Price [Roll Forward]
Balance as of December 31, 2019 (in dollars per share)	$ 2,968.22
Vested and expected to vest at December 31, 2019	3,286.28
Exercisable at December 31, 2019	$ 4,729.07
Weighted Average Remaining Contractual Term [Roll Forward]
Balance as of December 31, 2019	7 years 2 months 12 days
Vested and expected to vest at December 31, 2019	7 years 1 month 6 days
Exercisable at December 31, 2019	6 years 6 months

Stock-based Compensation - Weighted-average Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Black-Scholes-Merton option valuation model based on weighted-average assumptions [Abstract]
Expected term	7 years	7 years 1 month 6 days
Risk-free interest rate	2.41%	2.94%
Volatility	96.52%	92.87%
Resulting weighted average grant date fair value (in dollars per share)	$ 0.26	$ 1.74

Stock-based Compensation - Compensation Cost Recognized for Stock Options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Compensation cost recognized for the stock options and restricted stock awards [Abstract]
Total compensation cost for share-based payment arrangements recognized in the statement of operations (net of tax of $0)	$ 127	$ 355

Stock-based Compensation - Compensation Cost Recognized for Stock Options (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Total compensation cost for share-based payment arrangement, net of tax	$ 0	$ 0

Subsequent Events - Additional Information (Details) - USD ($)				12 Months Ended
	Mar. 29, 2020	Dec. 31, 2018	May 29, 2015	Dec. 31, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Repayment of debt				$ 3,692,000	$ 0
Subsequent Event [Member]
Subsequent Event [Line Items]
License fee payment in cash	$ 400,000
License fee payment in common stock	$ 300,000
Term Loan [Member]
Subsequent Event [Line Items]
Debt principal repayment start date				May 01, 2020
Maturity date		Jun. 01, 2020	Jun. 01, 2019	Jun. 01, 2021
Term Loan [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Debt principal repayment start date	May 01, 2021
Repayment of debt	$ 5,000,000
Maturity date	Jun. 01, 2024