Plus Therapeutics (PSTV) 8-K 10 Sep 19 Other Events Financial data

Document And Entity Information

Document And Entity Information	3 Months Ended
	Mar. 31, 2019
Document And Entity Information [Line Items]
Entity Registrant Name	PLUS THERAPEUTICS, INC.
Document Type	8-K
Amendment Flag	false
Entity Central Index Key	0001095981
Document Period End Date	Mar. 31, 2019
Entity Incorporation, State or Country Code	DE
Entity File Number	001-34375
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
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Entity Emerging Growth Company	false
Common Stock, par value $0.001 [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.001
Trading Symbol	PSTV
Security Exchange Name	NASDAQ
Series S Warrant [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	Series S Warrant
Trading Symbol	PSTVZ
Security Exchange Name	NASDAQ

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 3,872	$ 5,261	$ 9,550
Accounts receivable	253	178	130
Restricted cash	40	40	675
Inventories, net	107	107	107
Other current assets	736	785	780
Current assets held for sale	3,454	3,277	3,622
Total current assets	8,462	9,648	14,864
Property and equipment, net	2,384	2,299	2,325
Operating lease right-of-use assets	1,123
Other assets	40	39	42
Noncurrent assets held for sale	12,235	11,633	14,012
Goodwill	372	372	372
Total assets	24,616	23,991	31,615
Current liabilities:
Accounts payable and accrued expenses	2,729	2,777	4,206
Operating lease liability	345
Term obligations, net of discount	14,371	14,202	13,624
Current liabilities held for sale	850	580	584
Total current liabilities	18,295	17,559	18,414
Other noncurrent liabilities	28	46
Noncurrent operating lease liability	778
Warrant liability	706	916
Noncurrent liabilities held for sale	952	245	201
Total liabilities	20,759	18,766	18,615
Commitments and contingencies
Stockholders’ equity:
Preferred stock
Common stock	0	0	0
Additional paid-in capital	420,312	418,390	413,362
Accumulated other comprehensive income	1,078	1,218	1,387
Accumulated deficit	(417,533)	(414,383)	(401,749)
Total stockholders’ equity	3,857	5,225	13,000
Total liabilities and stockholders’ equity	$ 24,616	$ 23,991	$ 31,615

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018	May 24, 2018	May 23, 2018	Dec. 31, 2017
Stockholders’ equity:
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001			$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	30,223	30,223			30,223
Preferred stock, shares outstanding (in shares)	4,540	4,606			2,431
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001		$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000	100,000,000	75,000,000	100,000,000
Common stock, shares issued (in shares)	438,116	296,609	6,200,000	61,600,000	115,651
Common stock, shares outstanding (in shares)	438,116	296,609	6,200,000	61,600,000	115,651

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Development revenues:
Government contracts and other	$ 737	$ 917	$ 2,983	$ 3,722
Total development revenues	737	917	2,983	3,722
Operating expenses:
Research and development	1,426	1,395	5,523	5,073
Sales and marketing	114	294	643	1,341
General and administrative	1,363	2,098	5,579	6,700
In process research and development acquired from Azaya			0	1,686
Total operating expenses	2,903	3,787	11,745	14,800
Operating loss	(2,166)	(2,870)	(8,762)	(11,078)
Other income (expense):
Interest income	7	14	43	33
Interest expense	(515)	(423)	(1,922)	(2,049)
Change in fair value of warrants	210	0	2,233	0
Issuance cost of warrants			(470)	0
Total other expense	(298)	(409)	(116)	(2,016)
Loss from continuing operations	(2,464)	(3,279)	(8,878)	(13,094)
Loss from discontinued operations	(686)	(1,130)	(3,756)	(9,592)
Net loss	(3,150)	(4,409)	(12,634)	(22,686)
Net loss from continuing operations	$ (2,464)	$ (3,279)	(8,878)	(13,094)
Beneficial conversion feature for convertible preferred stock			2,487	3,977
Net loss from continuing operations allocable to common stockholders			(11,365)	(17,071)
Net loss from discontinued operations allocable to common stockholders			(3,756)	(9,592)
Net loss allocable to common stockholders			$ (15,121)	$ (26,663)
Basic and diluted net loss per share allocable to common stockholders – continuing operations	$ (6.98)	$ (27.24)	$ (65.37)	$ (263.53)
Basic and diluted net loss per share allocable to common stockholders – discontinued operations	(1.94)	(9.39)	(21.61)	(148.07)
Basic and diluted net loss per share allocable to common stockholders	$ (8.92)	$ (36.63)	$ (86.98)	$ (411.60)
Basic and diluted weighted average shares used in calculating net loss per share allocable to common stockholders	353,142	120,356	173,851	64,780
Comprehensive loss:
Net loss	$ (3,150)	$ (4,409)	$ (12,634)	$ (22,686)
Other comprehensive income – foreign currency translation adjustments	(140)	(281)	(169)	129
Comprehensive loss	$ (3,290)	$ (4,690)	$ (12,803)	$ (22,557)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Series B Convertible Preferred Stock [Member]	Series C Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member]	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 Convertible Preferred Stock [Member]	Common Stock [Member]Series C Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Series B Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]Series C Convertible Preferred Stock [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2016	$ 10,986									$ 388,791			$ 1,258	$ (379,063)
Balance (in shares) at Dec. 31, 2016							43,416
Share-based compensation	753									753
Issuance of common stock under employee stock purchase plan	1									1
Issuance of common stock under employee stock purchase plan (in shares)							2
Sale/Issuance of common stock	12,716	$ 8,767								12,716	$ 8,767
Sale/Issuance of common stock (in shares)					10,000		24,474
Conversion of Convertible Preferred Stock into common stock		23									23
Conversion of Convertible Preferred Stock into common stock (share)					(7,569)			45,413
Issuance of common stock as part of Azaya Therapeutics acquisition, net	2,311									2,311
Issuance of common stock as part of Azaya Therapeutics acquisition, net (shares)							2,346
Beneficial conversion feature related to Series B Convertible Preferred Stock		3,977									3,977
Accretion of beneficial conversion feature related to Series B Convertible Preferred Stock		$ (3,977)									$ (3,977)
Foreign currency translation adjustment and accumulated other comprehensive income	129												129
Net loss	(22,686)													(22,686)
Balance at Dec. 31, 2017	$ 13,000									413,362			1,387	(401,749)
Balance (in shares) at Dec. 31, 2017	115,651			2,431			115,651
Share-based compensation	$ 143									143
Sale/Issuance of common stock	27									27
Sale/Issuance of common stock (in shares)							201
Conversion of Convertible Preferred Stock into common stock (share)					(1,228)			7,375
Foreign currency translation adjustment and accumulated other comprehensive income	(281)												(281)
Net loss	(4,409)													(4,409)
Balance at Mar. 31, 2018	8,480									413,532			1,106	(406,158)
Balance (in shares) at Mar. 31, 2018				1,203			123,227
Balance at Dec. 31, 2017	$ 13,000									413,362			1,387	(401,749)
Balance (in shares) at Dec. 31, 2017	115,651			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 B Convertible Preferred Stock			2,487									2,487
Accretion of beneficial conversion feature related to Series B 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	$ 49									49
Sale/Issuance of common stock	1,873									1,873
Sale/Issuance of common stock (in shares)							139,855
Conversion of Convertible Preferred Stock into common stock (share)						(66)			1,652
Foreign currency translation adjustment and accumulated other comprehensive income	(140)												(140)
Net loss	(3,150)													(3,150)
Balance at Mar. 31, 2019	$ 3,857									$ 420,312			$ 1,078	$ (417,533)
Balance (in shares) at Mar. 31, 2019	438,116			4,540			438,116

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (3,150)	$ (4,409)	$ (12,634)	$ (22,686)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	443	497	2,004	2,151
Amortization of deferred financing costs and debt discount	168	105	578	707
In process research and development acquired from Azaya Therapeutics			0	1,686
Change in fair value of warrants	(210)	0	(2,233)	0
Allocation of issuance cost associated with warrants			470	0
Provision for doubtful accounts			18	0
Provision for excess inventory	0	326	463	340
Share-based compensation expense	49	143	355	753
Loss (gain) on asset disposal	0	22	36	(42)
Increases (decreases) in cash caused by changes in operating assets and liabilities:
Accounts receivable	(212)	(747)	(173)	1,129
Inventories	16	141	475	251
Other current assets	16	301	85	(593)
Other assets	1	(24)	23	(94)
Accounts payable and accrued expenses	(405)	(556)	(1,532)	(1,817)
Deferred revenues	(25)	84	73	(3)
Long-term deferred rent and other			17	90
Other long-term liabilities	39	(2)
Net cash used in operating activities	(3,270)	(4,119)	(11,975)	(18,128)
Cash flows from investing activities:
Purchases of property and equipment /long-lived assets	(6)	(53)
Proceeds from sale of assets			0	113
Net cash used in investing activities	(6)	(53)	(133)	(1,383)
Cash flows from financing activities:
Principal payments on long-term obligations			0	(4,720)
Financed capital expenditures			(66)	0
Proceeds from sale of common stock, net	1,919	(150)	0	0
Proceeds from sale of common and preferred stock			8,766	23,613
Costs from sale of common and preferred stock			(1,532)	(2,078)
Net cash provided by financing activities	1,891	(150)	7,168	16,815
Payment of financing lease liability	(28)
Effect of exchange rate changes on cash and cash equivalents	(4)	39	16	11
Net decrease in cash and cash equivalents	(1,389)	(4,283)	(4,924)	(2,685)
Cash, cash equivalents, and restricted cash at beginning of period	5,301	10,225	10,225	12,910
Cash, cash equivalents, and restricted cash at end of period	3,912	5,942	5,301	10,225
Cash paid during period for:
Interest	347	311	1,331	1,364
Supplemental schedule of non-cash investing and financing activities:
Conversion of preferred stock into common stock	$ 0	$ 4	8	23
Fair value of Series C and Series B Convertible Preferred Stock beneficial conversion feature			2,487	3,977
Property Plant And Equipment Excluding Research Lab Equipment And Leasehold Improvements [Member]
Cash flows from investing activities:
Purchases of property and equipment /long-lived assets			(133)	(295)
Assets Purchased from Azaya Therapeutics, Inc. [Member]
Cash flows from investing activities:
Purchases of property and equipment /long-lived assets			0	(1,201)
Supplemental schedule of non-cash investing and financing activities:
Common stock issued in payment for the assets acquired			$ 0	$ 2,311

Organization and Operations

Organization and Operations	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Operations	1. Organization and Operations The Company Plus Therapeutics, Inc. (“we”, “our” or the “Company”) 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 and Basis of Presentation The accompanying consolidated financial statements include our accounts and those of our subsidiaries. All significant intercompany transactions and balances have been eliminated in consolidation. During 2018 and 2017, 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. Accordingly, financial conditions and results of operations of the Cell Therapy business are presented as discontinued operations in the consolidated financial statements. Amendments to Certificate of Incorporation and Reverse Stock Split 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 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”. Additionally, the Company changed its trading symbol for its Series S warrants to “PSTVZ”. 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. There was no change in the Company’s Nasdaq ticker symbol, “PSTV,” as a result of the August 2019 Reverse Stock Split. 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 Amended and Restated 2004 Equity Incentive Plan, 2011 Employee Stock Purchase Plan, 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. All share and per share amounts have been adjusted retroactively to reflect the August 2019 Reverse Stock Split for all periods presented. Certain Risks and Uncertainties Our 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. Our future viability largely depends on our ability to complete development of new products and receive regulatory approvals for those products. No assurance can be given that our new products will be successfully developed, regulatory approvals will be granted, or acceptance of these products will be achieved. The development of medical devices for specific therapeutic applications is subject to a number of risks, including research, regulatory and marketing risks. There can be no assurance that our development stage products will overcome these hurdles and become commercially viable and/or gain commercial acceptance. Liquidity and Going Concern On a consolidated basis, we incurred net losses of $12.6 million for the twelve months ended December 31, 2018, including $3.8 million of net loss from discontinued operations. We have an accumulated deficit of $414.4 million as of December 31, 2018. Additionally, we used net cash of $12.0 million to fund our operating activities for the twelve months ended December 31, 2018. These factors raise substantial doubt about the Company’s ability to continue as a going concern. Further, the Loan and Security Agreement with Oxford, as further described in Note 8, requires the Company to maintain a minimum of $2.0 million in unrestricted cash and cash equivalents on hand to avoid an event of default under the Loan and Security Agreement and requires the Company to achieve one of the following by March 29, 2019: (i) enter into an asset sale agreement with a minimum unrestricted net cash proceeds to the Company of $4.0 million; or (ii) 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. Based on our cash and cash equivalents on hand of approximately $5.3 million at December 31, 2018, the Company estimates that it will need to raise additional capital and/or obtain a waiver or restructure the Loan and Security Agreement in the near term to avoid defaulting under its $2.0 million minimum cash/cash equivalents covenant. To date, these operating losses have been funded primarily from outside sources of invested capital including our recently completed 2018 Rights Offering (defined in Note 11), our Lincoln Park Purchase Agreement (defined in Note 11) with Lincoln Park Capital Fund, LLC (“Lincoln Park”), the ATM program (further defined below) initiated in June 2018, the 2017 Rights Offering (defined in Note 11), the Loan and Security Agreement and gross profits. We have had, and we will continue to have, an ongoing need to raise additional cash from outside sources to fund our future clinical development programs and other operations. Our inability to raise additional cash would have a material adverse impact on operations and would cause us to default on our loan. On April 11, 2017, we entered into an underwriting agreement (the “Underwriting Agreement”) with Maxim Group LLC “Maxim”) relating to the issuance and sale of 17,881 shares of our common stock. The price to the public in this offering was $550.00 per share. Maxim purchased the shares from us pursuant to the Underwriting Agreement at a price of $520.00 per share. The net proceeds to us from the offering were approximately $8.7 million, after deducting underwriting discounts and commissions and offering expenses payable by us. The offering closed on April 17, 2017. In addition, under the terms of the Underwriting Agreement, we granted Maxim a 45-day option to purchase up to 1,888 additional shares of common stock. On May 31, 2017, Maxim exercised their overallotment option and purchased 1,698 shares at $550.00 per share. The net proceeds to us were $0.8 million, after deducting underwriting costs and offering expenses payable by us. On September 5, 2017, we received a written notice from The Nasdaq Stock Market LLC (“Nasdaq”) indicating that, based upon the closing bid price of our common stock for the last 30 consecutive business days, we no longer met 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 a period of 180 calendar days, or until March 5, 2018, in which to regain compliance. We were granted an additional compliance period of 180 calendar days, or until September 4, 2018, 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 of our intent to cure the deficiency during the 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 our common stock must have been at least $1.00 per share for a minimum of ten consecutive business days during the second 180-day period. On June 8, 2018, we received written notice from Nasdaq that we had regained compliance with the Nasdaq Stock Market Listing Rule 5500(a)(2) concerning our minimum bid price per share of our common stock. On November 28, 2017, we closed a rights offering originally filed under a Form S-1 registration statement in August 2017 (“2017 Rights Offering”). Pursuant to the 2017 Rights Offering, the Company sold an aggregate of 10,000 units consisting of a total of 10,000 shares of Series B Convertible Preferred Stock, immediately convertible into approximately 60,000 shares of common stock and 360,000 warrants, exercisable for an aggregate of 36,000 shares of common stock at an exercise price of $166.65 per share of common stock, resulting in total net proceeds to the Company of $8.8 million. These warrants became exercisable on May 18, 2018. On June 1, 2018, we entered into a Sales Agreement with B. Riley FBR, Inc. (“B. Riley FBR”) to sell shares of our 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. Through December 31, 2018, we have sold a total of 1,584 shares for proceeds of approximately $1.7 million through the ATM program. See Note 11 for further discussion on the ATM program. On July 25, 2018, we 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, immediately convertible into approximately 168,478 shares of common stock and 7,059,150 warrants, with 50 warrants exercisable for one share of common stock at an exercise price of $39.93 per share, resulting in total net proceeds to the Company of approximately $5.7 million. On August 28, 2018, we 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, we 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. We were 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 our common stock must have been at least $1.00 per share for a minimum of ten consecutive business days during the 180-day period. On September 21, 2018, Plus entered into a purchase agreement and a registration rights 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. See Note 11 for further discussion on the Lincoln Park Agreement. We continue to seek additional capital through product revenues, strategic transactions, including extension opportunities under our awarded U.S. Department of Health and Human Service’s Biomedical Advanced Research and Development Authority (“BARDA”) contract Should we be unable to raise additional cash from outside sources, this would have a material adverse impact on our 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 Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
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. Our most significant estimates and critical accounting policies involve recognizing revenue, reviewing goodwill and intangible assets for impairment, determining the assumptions used in measuring share-based compensation expense, valuing warrants, measuring expense related to our in-process research and development acquisition, and valuing allowances for doubtful accounts and inventory reserves. 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 We consider 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. We held no investments as of December 31, 2018 and 2017. We maintain our cash at insured financial institutions. 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 $0.7 million naming the landlord as a beneficiary as of December 31, 2018 and 2017, respectively. Accounts Receivable Accounts receivable are recorded at the invoiced amount and do not bear interest. The Company periodically assesses the collectability of accounts receivable on a specific customer basis considering factors such as evaluation of collectability, historical collection experience, the age of accounts receivable and other currently available evidence of the collectability, and records an allowance for doubtful accounts for the estimated uncollectible amount. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. Inventories We periodically evaluate all inventories on hand and make appropriate provisions for any stock deemed excess or obsolete. Inventories related to our discontinued operations include the cost of material, labor, and overhead, and are stated at the lower of cost, determined on the first-in, first-out (FIFO) method, or net realizable value. Manufacturing costs resulting from lower than “normal” production levels are expensed as incurred. 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 We assess certain of our long-lived assets, such as property and equipment and intangible assets other than goodwill, 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. We recognized no impairment losses during any of the periods presented in these financial statements. Goodwill and Intangibles Goodwill is reviewed for impairment annually or more frequently if indicators of impairment exist. We perform our impairment test annually during the fourth quarter. As the Company operates in a single operating segment and reporting unit, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test. If, after assessing qualitative factors, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. If deemed necessary, a two-step test is used to identify the potential impairment and to measure the amount of goodwill impairment, if any. The first step is to compare the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill is considered not impaired; otherwise, there is an indication that goodwill may be impaired and the amount of the loss, if any, is measured by performing step two. Under step two, the impairment loss, if any, is measured by comparing the implied fair value of the reporting unit goodwill with the carrying amount of goodwill. We experienced significant volatility in our share price during the year. During Q3 2018 and Q4 2018, our stock price significantly declined in comparison to the corresponding previous quarters. We performed a valuation of our single reporting unit as of September 30, 2018 (and as updated for the annual test during the fourth quarter in 2018). Based upon the results of our valuation, management concluded that the fair value of the reporting unit exceeded its carrying value. We determined that a blending of the income approach and an option pricing model back-solve was a reasonable approximation of the fair value of the reporting unit. Additionally, a further reduction in our market capitalization could be an indicator of impairment. Given the volatility of our stock price a continued decline in market capitalization could result in an impairment of our goodwill. There was no change in our goodwill balance from December 31, 2017 to December 31, 2018. Separable intangible assets related to our discontinued operations that have finite useful lives are amortized over their respective useful lives. Warrant Liability Warrants with exercise price reset features (down-round protection) are accounted for as liabilities, with changes in the fair value included in net loss until they are either exercised or expire. In connection with the 2018 Rights Offering, in July 2018, the Company issued Series C Convertible Preferred Stock, immediately convertible into common stocks and warrants. The warrants may be redeemed by the Company at $0.50 per warrant prior to their expiration if the Company’s common stock closes above $181.50 per share, The warrants are not traded in an active securities market, and as such the estimated the fair value as of December 31, 2018 was determined by using an option pricing model with the following assumptions: As of December 31, 2018 As of July 25, 2018 (inception date) Common stock market price $ 14.50 $ 36.00 Risk-free interest rate 2.48 % 2.70 % Expected volatility 125 % 112 % Resulting fair value (per warrant) $ 6.50 $ 22.50 Expected term 2.1 years 2.5 years Expected volatility was computed using daily pricing observations of traded shares of Plus for recent periods that correspond to the expected term of the warrants. We believe this method produces an estimate that is representative of our expectations of future volatility over the expected term of these warrants. We currently have 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, most significantly the assumption with regards to future equity issuances and its impact to the down-round protection feature. Significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement. Refer to Note 4 for a discussion of the change in our 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. We recognized $3.0 million and $3.7 million in BARDA revenue for the years ended December 31, 2018 and 2017, respectively. Concentration of Significant Customers After the sale of our Cell Therapy business, BARDA accounted for 100% of our revenue from continuing operations which are recognized for the year ended December 31, 2018 and 2017. BARDA also 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 design, development, testing and enhancement of our product candidates, 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 $2.7 million and $3.5 million of qualified expenses that were incurred for the years ended December 31, 2018 and 2017, 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, 2018 and 2017, 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 We recognize 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. We estimate 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 we do 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, 2018 and 2017, 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 and warrants for all periods presented. We have excluded all potentially dilutive securities, including unvested performance-based restricted stock, from the calculation of diluted loss per share attributable to common stockholders for the years ended December 31, 2018 and 2017, as their inclusion would be antidilutive. Potentially dilutive securities excluded from the calculations of diluted loss per share were 0.3 million as of December 31, 2018, which includes 0.2 million outstanding warrants and 2,753 options, 94,589 of preferred stocks, and restricted stock awards. Potentially dilutive securities excluded from the calculations of diluted loss per share were 9,458 as of December 31, 2017. Recently Issued and Recently Adopted Accounting Pronouncements Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases 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. We are currently evaluating the impact that this standard will have on our consolidated financial statements. Recently Adopted Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers In November 2016, the FASB issued ASU 2016-18, Restricted Cash

Discontinued Operations

Discontinued Operations	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
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 will be finalized during the fourth quarter of 2019 (in thousands): Consideration received $ 7,000 Transaction costs (1,161 ) Net cash proceeds 5,839 Less: Carrying value of business and assets sold 12,145 Net loss on sale of business $ 6,306 Assets and liabilities related to discontinued operations or held for sale consisted of the following: March 31, 2019 December 31, 2018 Assets Current assets held for sale: Accounts receivable, net $ 202 $ 108 Inventory, net 2,896 2,841 Other current assets 356 328 Long-term assets held for sale: Property and equipment, net 223 260 Operating lease right-of-use assets 1,030 — Other noncurrent assets 1,787 1,866 Goodwill 3,550 3,550 Intangible assets, net 5,645 5,957 Total assets $ 15,689 $ 14,910 Liabilities Current liabilities held for sale: Accounts payable and accrued liabilities $ 495 $ 580 Operating lease liabilities 355 — Noncurrent liabilities held for sale: Other noncurrent liabilities 70 78 Operating lease liabilities 740 — Deferred revenues 142 167 Total liabilities held for sale $ 1,802 $ 825 The following table summarizes the results of discontinued operations for the periods presented (in thousands): Three months ended March 31, 2019 2018 Product revenue $ 703 $ 731 Cost of revenues 659 579 Gross profit 44 152 Operating expenses: Research and development 420 1,104 Sales and marketing 314 384 General and administrative 145 146 Total operating expenses 879 1,634 Operating loss (835 ) (1,482 ) Other income (expense) 149 352 Loss from discontinued operations $ (686 ) $ (1,130 ) During the three and six months ended June 30, 2019 and 2018, 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 removed from 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 three months ended March 31, 2019 2018 Depreciation and amortization $ 344 $ 393 Provision for excess inventory $ — $ 326 Loss on asset disposal $ — $ 22	3. 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 will be finalized during the fourth quarter of 2019 (in thousands): Consideration received $ 7,000 Transaction costs (1,161 ) Net cash proceeds 5,839 Less: Carrying value of business and assets sold 12,145 Net loss on sale of business $ 6,306 Assets and liabilities related to discontinued operations or held for sale consisted of the following: December 31, 2018 December 31, 2017 Assets Current assets held for sale: Accounts receivable, net $ 108 $ 15 Inventory, net 2,841 3,076 Other current assets 328 531 Long-term assets held for sale: Property and equipment, net 260 727 Other noncurrent assets 1,866 2,528 Goodwill 3,550 3,550 Intangible assets, net 5,957 7,207 Total assets $ 14,910 $ 17,634 Liabilities Current liabilities held for sale: Accounts payable and accrued liabilities $ 580 $ 584 Noncurrent liabilities held for sale: Other noncurrent liabilities 78 107 Deferred revenues 167 94 Total liabilities held for sale $ 825 $ 785 The following table summarizes the results of discontinued operations for the periods presented (in thousands): Year ended December 31, 2018 2017 Product revenue $ 2,671 $ 2,689 License revenue 1,000 — Total revenues 3,671 2,689 Cost of revenues 2,373 2,543 Gross profit 1,298 146 Operating expenses: Research and development 3,099 6,605 Sales and marketing 1,375 2,252 General and administrative 760 894 Total operating expenses 5,234 9,751 Operating loss (3,936 ) (9,605 ) Other income (expense) 180 13 Loss from discontinued operations $ (3,756 ) $ (9,592 ) During year ended December 31, 2018 and 2017, 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 removed from 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, 2018 2017 Depreciation and amortization $ 1,625 $ 1,630 Provision for excess inventory $ 463 $ 340 (Loss) gain $ (36 ) $ 40 The changes in the carrying amounts of finite-life intangible assets related to our discontinued operations for the years ended December 31, 2018 and 2017 are as follows (in thousands): December 31, 2018 December 31, 2017 Intangibles, net: Beginning balance $ 7,207 $ 8,447 Increase — — Amortization (1,250 ) (1,240 ) Ending balance $ 5,957 $ 7,207

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value	4. 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. As of December 31, 2017, we did not have any asset or liability measured at fair value presented on our balance sheet. Warrants with exercise price reset features (down-round protection) are accounted for as liabilities, with changes in the fair value included in net loss for the respective periods. 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 following table summarizes the change in our Level 3 warrant liability value (in thousands): Years ended December 31, Warrant liability 2018 2017 Beginning balance $ 3,149 $ — Change in fair value (2,233 ) — Ending balance $ 916 $ — Financial Instruments We disclose fair value information 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, 2018 and 2017, 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. Further, based on the borrowing rates currently available for loans with similar terms, we believe the fair value of long-term debt approximates its carrying value. At December 31, 2018 and 2017, the aggregate fair value and the carrying value of the Company’s long-term debt were as follows (in thousands): December 31, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value Debt $ 14,043 $ 14,202 $ 13,427 $ 13,624 Carrying value is net of debt discount of $0.6 million and $0.4 million as of December 31, 2018 and 2017, 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 our 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 We apply fair value techniques on a non-recurring basis 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.

Asset Purchase Agreement with A

Asset Purchase Agreement with Azaya Therapeutics	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
Asset Purchase Agreement with Azaya Therapeutics	5. Asset Purchase Agreement with Azaya Therapeutics On February 15, 2017 (the “Closing Date”), we completed the acquisition from Azaya Therapeutics, Inc. (“Azaya”) of certain tangible assets which consisted of a research lab, equipment and leasehold improvements and the assumption of certain of liabilities of Azaya, pursuant to an Asset Purchase Agreement (the “Agreement”). The book value of the tangible assets acquired was approximately $3.0 million at the acquisition date. The assets acquired are located in a facility rented in San Antonio, TX, by Plus. In addition, pursuant to the Agreement, we acquired intangible assets comprised of two drug candidates in process research and development (IPR&D) stage (i) ATI-0918, a generic bioequivalent formulation of Doxil ® ® At the closing of the acquisition, we (i) issued 117,325 of shares of our common stock in Azaya’s name, (A) 87,994 of which were delivered to Azaya promptly after the Closing, and (B) 29,331 of which were deposited into a 15-month escrow pursuant to a standard escrow agreement; and (ii) assumed the obligation to pay approximately $1.8 million of Azaya’s existing payables, all of which were paid prior December 31, 2017. At the Closing Date, Azaya had no employees and therefore no Azaya employees were transitioned to us. In addition, as of the Closing Date, the Company committed to certain contingent consideration to: (i) pay Azaya fixed commercialization milestone payments based upon achievement of certain net sales milestones for ATI-0918; (ii) make certain earn-out payments to Azaya equal to a mid-single-digit percentage of net sales of ATI-0918; and (iii) make certain earn-out payments to Azaya equal to a low single-digit percentage of net sales of any product (ATI-0918 is the “Generic Product” and ATI-1123 is the “Patented Product”), including ATI-1123, that practices a claim in the related patent assigned by Azaya to the Company (the “ATI-1123 Patent”). Our aggregate earn-out payment obligations to Azaya from global net sales of both ATI-0918 and any Patented Product will not exceed $100.0 million (the “Earn-Out Cap”). Further, the Agreement provides that if we enter into certain assignments, licenses or other transfers of rights to a Patented Product or the ATI-1123 Patent, we will pay Azaya a percentage in the low to mid-teens of the consideration received by us, provided, that our aggregate payment obligation to Azaya for any such assignment, license or other transfer of rights will not exceed $50.0 million. If the Company or its successors, sublicenses or transferees sells a competing product to ATI-0918 at any time prior to satisfaction of the Earn-Out Cap, other than because ATI-0918 fails to receive marketing authorization from the European Medicines Agency within a certain period of time or fails to generate a minimum threshold of net sales within a pre-determined amount of time, then 50% of the net sales of such competing product would be deemed to be net sales of ATI-0918 under the Agreement for purposes of calculating commercialization milestone payments and earn-out payments. We accounted for the acquisition as an asset acquisition because the acquired set of assets did not meet the definition of a business. The total consideration of $4.3 million, which consists of $2.3 million related to the fair value of the common stock issued to Azaya at the acquisition date, $1.8 million in assumed liabilities and $0.2 million in acquisition costs, was allocated to the assets acquired based on their relative fair values at the time of acquisition. All other future payments were deemed contingent consideration which will be accounted for when the contingency is resolved and the consideration is paid or becomes payable. When determining the fair value of tangible assets acquired, the Company estimated the cost to replace the tangible asset with a new asset, taking into consideration such factors as age, condition and the economic useful life of the asset. When determining the fair value of intangible assets acquired, the Company used a discounted cash flow model with key inputs being the applicable discount rate, market growth rates and the timing and amount of future cash flows. The acquired IPR&D is in the early stage of development. Additional research, pre-clinical studies, and regulatory approvals must be successfully completed prior to selling any product. Because there is no current alternative use for the IPR&D, following the authoritative accounting guidance, the Company has expensed it in full on the Closing Date. The Company measured the fair value of the shares issued as consideration in the acquisition of the assets based on the stock price at the acquisition date. Transaction costs directly related to the acquisition of the assets have been capitalized. The total consideration was allocated on a relative fair value basis to the assets acquired, as follows (in thousands): February 15, 2017 Tangible assets $ 2,586 Intangible assets 1,686 Total assets $ 4,272 Accounts payable $ 1,796 Fair value of the common stock issued 2,311 Transaction costs 165 Total consideration $ 4,272

Composition of Certain Financia

Composition of Certain Financial Statement Captions	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017, other current assets were comprised of the following (in thousands): December 31, 2018 2017 Prepaid services, current $ 166 $ 121 Prepaid insurance 564 556 Other receivables 55 103 $ 785 $ 780 Property and Equipment, net As of December 31, 2018 and 2017, property and equipment, net, were comprised of the following (in thousands): December 31, 2018 2017 Office and computer equipment $ 1,279 $ 1,041 Leasehold improvements 1,682 1,686 Property and equipment – gross 2,961 2,727 Less accumulated depreciation (662 ) (402 ) Property and equipment – net $ 2,299 $ 2,325 Depreciation expense totaled $0.3 million and $0.4 million for the years ended December 31, 2018 and 2017, respectively. Other Assets As of December 31, 2018 and 2017, other assets were comprised of the following (in thousands December 31, 2018 2017 Deposits $ 39 $ 42 $ 39 $ 42 Accounts Payable and Accrued Expenses As of December 31, 2018 and 2017, accounts payable and accrued expenses were comprised of the following (in thousands): December 31, 2018 2017 Accrued expenses $ 824 $ 1,182 Accounts payable 721 1,297 Accrued payroll and bonus 423 750 Accrued legal fees 186 509 Accrued vacation 192 64 Accrued R&D studies 230 285 Other current liabilities 201 119 $ 2,777 $ 4,206

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies 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, 2018, we have clinical research study obligations of $3.0 million, $1.8 million of which is expected to be paid within a year. Should the timing of the clinical trials change, the timing of the payment of these obligations would also change. We lease facilities for our headquarters office location as well as satellite office locations. As of December 31, 2018, we have contractual lease obligations to make payments on leases of office and manufacturing space as follows: Years Ending December 31, Obligation 2019 $ 1,282 2020 638 2021 638 2022 192 Total $ 2,750 Rent expense, which includes common area maintenance, for the years ended December 31, 2018 and 2017 was $1.4 million and $1.6 million, respectively. On February 27, 2017, we entered into a Lease Agreement of office space for our corporate headquarters in San Diego, California (the “Lease”). The initial term of the Lease is 63 months and may be extended upon mutual agreement. The commencement date was originally expected to take place in November 2017 and subsequently amended to January 1, 2018. In connection with our restructuring announced in September 2017, we began negotiations with the landlord and in February 2018, announced a buy-out of our obligations with the Lease of approximately $0.6 million, included in the general and administrative expenses. 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. Management believes that any liability to us that may arise as a result of currently pending legal proceedings will not have a material adverse effect on our financial condition, liquidity, or results of operations as a whole. On April 27, 2018, Lorem Vascular (“Lorem”) filed suit against the Company in the U.S. District Court for the Southern District of California alleging the Company breached an oral agreement made in 2013 to purchase 5% of Lorem’s common stock for an aggregate amount of $5.0 million, and seeking specific performance of the alleged oral agreement and damages in an amount to be determined at trial. The Company filed a motion to dismiss all of Lorem’s claims, and on July 11, 2018 the Court granted the Company’s motion to dismiss. Lorem filed an amended complaint on August 3, 2018, advancing similar causes of action and seeking similar relief. Plus filed a renewed motion to dismiss on August 27, 2018, and on October 1, 2018, Lorem voluntarily dismissed its amended complaint in its entirety. On August 31, 2018, we filed a Demand for Arbitration with the American Arbitration Association in San Diego, California, against Bimini Technologies LLC (“Bimini”) for fraud and breach of a Sale and Exclusive License/Supply Agreement made in 2013 under which Bimini licensed rights to the Company’s Standalone Fat Transplantation, including the Puregraft Product Line and associated trademarks. Our arbitration demand alleged that Bimini failed to make a $1.0 million milestone payment due to the Company after Bimini achieved $10.0 million in gross profits from the sale of the Company’s Puregraft product line, and Bimini deceived the Company about Bimini’s true gross profits figures. Our arbitration demand sought that $1.0 million milestone payment, as well prejudgment interest and attorneys’ fees. On October 29, 2018 Bimini made the $1.0 million milestone payment. The parties subsequently entered into a settlement agreement resolving the claims in the Demand for Arbitration.

Term Loan Obligations

Term Loan Obligations	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Term Loan Obligations	5. Term Loan Obligations On May 29, 2015, the Company entered into the Loan and Security Agreement, dated May 29, 2015, 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 is due and payable in full on June 1, 2019. 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. On September 20, 2017, the Company entered into an amendment to the Term Loan, pursuant to which, among other things, Oxford agreed to reduce the minimum liquidity covenant level originally at $5 million to $1.5 million. The amendment also extended the interest-only period under the Loan and Security Agreement through August 1, 2018, as the Company successfully closed on a financing and received unrestricted net cash proceeds in excess of $5 million on or before December 29, 2017. On June 19, 2018, the Company entered into a second amendment (the “Second Amendment”) to the Term Loan with Oxford. The Second Amendment extends the interest-only period under the Term Loan to December 1, 2018 if the Company receives unrestricted gross cash proceeds of at least $15 million from the sale and issuance of the Company’s equity securities on or before August 31, 2018. 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 Fourth Amendment increased the minimum liquidity covenant level from $1.5 million to $2.0 million and extended the interest-only period under the Loan and Security Agreement to March 1, 2019. The Fourth Amendment also required 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 and Security 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 (the “Fifth Amendment”) to the Term Loan primarily to 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 to the Term Loan primarily to extend the Fifth Amendment obligations 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. See Note 13 for further discussion on the Seventh 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 level when the total principal outstanding under the Loan and Security Agreement is less than $3 million. As of March 31, 2019, we were in compliance with all of the debt covenants under the Loan and Security Agreement. Our interest expense for the three months ended March 31, 2019 and 2018 was $0.5 million and $0.4 million, respectively. Interest expense is calculated using the effective interest method, therefore it is inclusive of non-cash amortization in the amount of $0.2 million for the three months ended March 31, 2019 and $0.1 million for the three months ended March 31, 2018 , related to the amortization of the debt discount, capitalized loan costs, and accretion of final payment. The Loan and Security Agreement, as amended, 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 March 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 is presented as 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.	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 is due and payable in full on June 1, 2019. 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. On September 20, 2017, the Company entered into an amendment to the Term Loan, pursuant to which, among other things, Oxford agreed to reduce the minimum liquidity covenant level originally at $5 million to $1.5 million. The amendment also extended the interest-only period under the Loan Agreement through August 1, 2018, as the Company successfully closed on a financing and received unrestricted net cash proceeds in excess of $5 million on or before December 29, 2017. On June 19, 2018, the Company entered into a second amendment (the “Second Amendment”) to the Term Loan with Oxford. The Second Amendment extends the interest-only period under the Term Loan to December 1, 2018 if the Company receives unrestricted gross cash proceeds of at least $15 million from the sale and issuance of the Company’s equity securities on or before August 31, 2018. 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. 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, 2018, 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, 2018, 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, 2018 and 2017 are presented in the following table (in thousands): 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 Year ended December 31, 2017 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 2017, which reflects interest only ** 3 month LIBOR rate with a floor of 1% plus 7.95% *** Monthly payment as of December 2018, which reflects interest only As of December 31, 2018, the future contractual principal and final fee payments on all of our debt and capital lease obligations are as follows (as thousands): Years Ending December 31, 2019 $ 8,653 2020 6,090 Total $ 14,743 Reconciliation of Face Value to Book Value as of December 31, 2018 Total debt and lease obligations, including final payment fee (Face Value) $ 14,743 Less: Debt discount (541 ) Total obligation $ 14,202 Our interest expense for the years ended December 31, 2018 and 2017 was $1.9 million and $2.0 million, respectively. Interest expense is calculated using the effective interest method, therefore it is inclusive of non-cash amortization in the amount of $0.6 million and $0.7 million, respectively, related to the amortization of the debt discount, capitalized loan costs, and accretion of final payment.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes Due to our net losses from continuing operations for the years ended December 31, 2018 and 2017, and since the Company has recorded a full valuation allowance against deferred tax assets, there was no provision or benefit for income taxes recorded. The components of income/(loss) before income tax provision (benefit) from continuing operations as of December 31, 2018 and 2017 are as follows (in thousands): 2018 2017 U.S. $ (8,346 ) $ (12,230 ) Foreign (507 ) (843 ) $ (8,853 ) $ (13,073 ) A reconciliation of the total income tax provision tax rate from continuing operations to the statutory federal income tax rates of 21% and 34% for the years ended December 31, 2018 and 2017, respectively, is as follows: 2018 2017 Income tax expense (benefit) at federal statutory rate (21.0 )% (34.0 )% Income tax expense (benefit) at state statutory rate (8.2 )% (6.7 )% Change in valuation allowance 35.8 % (324.5 )% Change in state rate (0.1 )% (1.5 )% Permanent interest adjustments 0.7 % 0.4 % Stock compensation 1.8 % 5.2 % Research credit (1.4 )% (1.9 )% Foreign rate differential — 350.4 % NOLs expiring and adjustments to NOL — 12.1 % Mark to market adjustment (5.3 )% — Other, net (2.3 )% 0.5 % 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, 2018 and 2017 are as follows (in thousands): 2018 2017 Deferred tax assets: Allowances and reserves $ 270 $ 140 Accrued expenses 122 154 Stock based compensation 996 1,065 Net operating loss carryforwards 91,197 87,426 Income tax credit carryforwards 8,671 8,587 Property and equipment, principally due to differences in depreciation 548 514 Other, net 38 45 101,842 97,931 Valuation allowance (101,091 ) (97,089 ) Total deferred tax assets, net of allowance 751 842 Deferred tax liabilities: Intangibles assets (751 ) (842 ) Total deferred tax liability (751 ) (842 ) 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 evaluate 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 $101.1 million as of December 31, 2018 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 $4.0 million during the year ended December 31, 2018. At December 31, 2018, we had federal, and state tax loss carry forwards of approximately $380.6 million, and $156.8 million, respectively. The federal and state net operating loss carry forwards begin to expire in 2019 and 2028, respectively, if unused. The federal net operating loss carryover includes $13.1 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, 2018, we had federal and state tax credit carry forwards of approximately $5.2 million and $4.5 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 2019, 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. In December 2017, the Tax Cuts and Jobs Act (the "2017 Act) was enacted. The 2017 Tax Act includes a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. corporate income tax rate from 35 percent to 21 percent for tax years beginning after December 31, 2017. In 2017 and in the first nine months of 2018, the Company recorded provisional amounts for certain enactment-date effects of the act by applying the guidance in Staff Accounting Bulletin No. 118 ("SAB 118") because we had not completed our accounting for these effects. In 2018 and 2017, the Company recorded $0 net tax expense related to the enactment-date effects of the Act related to the remeasurement of deferred tax assets and liabilities. There were no changes made in 2018 to our 2017 enactment-date provisional amounts. The Company applied the guidance in SAB 118 when accounting for the enactment-date effects of the Act in 2017 and throughout 2018. At December 31, 2017, the Company had not completed its accounting for all of the enactment-date income tax effects of the Act under ASC 740, Income Taxes, related to the remeasurement of deferred tax assets and liabilities. At December 31, 2018, the Company has now completed our accounting for all of the enactment-date income tax effects of the Act and no adjustments were made to the provisional amounts recorded at December 31, 2017. As of December 31, 2017, the Company remeasured certain deferred tax assets and liabilities based on the rates at which they were expected to reverse in the future (which was generally 21%), by recording a provisional amount of $45.8 million, which was fully offset by valuation allowance. Upon further analysis of certain aspects of the Act and refinement of our calculations during the 12 months ended December 31, 2018, the Company determined that no adjustment was necessary to our provisional amount. 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, 2018 and 2017. Following is a tabular reconciliation of the unrecognized tax benefits activity during the years ended December 31, 2018 and 2017 (in thousands): 2018 2017 Unrecognized Tax Benefits – Beginning $ 2,157 $ 2,062 Gross increases – tax positions in prior period 1 — Gross decreases – tax positions in prior period (3 ) — Gross increase – current-period tax positions 61 95 Unrecognized Tax Benefits – Ending $ 2,216 $ 2,157 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, 2018. The Company’s material tax jurisdictions are 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 1998 (federal) and 1997 (CA) and forward can be subject to examination by the United States and California tax authorities due to the carry forward of net operating losses and research development credits.

Employee Benefit Plan

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 2018 or 2017.

Stockholders' Equity

Stockholders' Equity	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Stockholders Equity Note [Abstract]
Stockholders' Equity	12. 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 13,500 shares of Series A 3.6% Convertible Preferred Stock, 10,000 Series B Convertible Preferred Stock and 6,723 Series C Convertible Preferred Stock that had been issued at March 31, 2019 and December 31, 2018, respectively. There were no shares of Series A 3.6% Convertible Preferred Stock outstanding as of either date. There were 1,112 of Series B Convertible Preferred Stock outstanding as of March 31, 2019 and December 31, 2018. There were 3,428 and 3,494 shares of Series C Preferred Stock outstanding as of March 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. The warrants are exercisable for an aggregate of 141,183 shares of the Company’s common stock at an exercise price of $39.93 per share for 30 months from the date of issuance and each share of Series C Preferred Stock is convertible into 25 shares of the Company's common stock. 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. 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. We recorded a deemed dividend within additional paid-in capital of $2.5 million for the quarter ended December 31, 2018, related to a beneficial conversion feature included in the issuance of our Series C Convertible Preferred Stock. Based on the relevant authoritative accounting guidance, the warrants were liability classified at the issuance date. The warrants may be redeemed by the Company at $0.50 per warrant prior to their expiration if the Company’s common stock closes above $181.50 per share, As of March 31, 2019 As of December31, 2018 Expected term 1.8 years 2.1 years Common stock market price $ 13.00 $ 14.50 Risk-free interest rate 2.38 % 2.48 % Expected volatility 128 % 125 % Resulting fair value (per warrant) $ 5.00 $ 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. We believe this method produces an estimate that is representative of our expectations of future volatility over the expected term of these warrants. We currently have 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. The following table summarizes the change in our Level 3 warrant liability value (in thousands): Warrant liability March 31, 2019 December 31, 2018 Beginning balance $ 916 $ 3,149 Change in fair value (210 ) (2,233 ) Ending balance $ 706 $ 916 Common Stock 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 March 31, 2019, the Company sold a total of 0.2 million shares for proceeds of approximately $3.8 million through the ATM program. On September 21, 2018, the Company entered into a Purchase Agreement (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. The Company may direct Lincoln Park, at its sole discretion and subject to certain conditions, to purchase up to 5,000 shares of common stock on any business day but in no event will the amount of a single Regular Purchase (as defined in the Lincoln Park Purchase Agreement) exceed $1.0 million. The purchase price of shares of common stock related to the Regular Purchases will be based on the prevailing market prices of such shares at the time of sales. The Company’s sales of shares of common stock to Lincoln Park under the Lincoln Park Purchase Agreement are limited to the number of shares that would result in the beneficial ownership by Lincoln Park and its affiliates, at any single point in time, of no more than 4.99% of the then outstanding shares of the common stock. There are no trading volume requirements or restrictions under the Lincoln Park Purchase Agreement. There is no upper limit on the price per share that Lincoln Park must pay for common stock under a Regular Purchase or an accelerated purchase and in no event under an accelerated purchase will shares be sold to Lincoln Park on a day the closing price of the Company’s common stock is less than the floor price of $12.50 per share as set forth in the Lincoln Park Purchase Agreement. 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 and no shares were sold during the three months ended March 31, 2019.	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 13,500 shares of Series A 3.6% Convertible Preferred Stock and 10,000 Series B Convertible Preferred Stock that had been issued at December 31, 2018 and December 31, 2017, respectively. There were no shares of Series A 3.6% Convertible Preferred Stock outstanding as of either date. There were 1,112 and 2,431 shares of Series B Convertible Preferred Stock outstanding as of December 31, 2018 and December 31, 2017, respectively. There were 3,494 and 0 shares of Series C Preferred Stock outstanding as of December 31, 2018 and December 31, 2017, respectively. On November 27, 2017, the Company filed a Certificate of Designation of Preferences, Rights and Limitations of Series B Convertible Preferred Stock 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 B Convertible Preferred Stock”. The number of shares initially constituting the Series B Convertible Preferred Stock was set at 10,000 shares. Pursuant to a registration statement on Form S-1, originally filed on August 14, 2017, as amended, and declared effective by the U.S. Securities and Exchange Commission (“SEC”) on November 2, 2017, and related prospectus (as supplemented), the Company registered and distributed to holders of its common stock, at no charge, non-transferable subscription rights to purchase up to an aggregate of 10,000 units consisting of 10,000 shares of Series B Convertible Preferred Stock and 18 million warrants, with every 10 warrants exercisable for one common stock at an exercise price of $3.333 per share for 30 months from the date of issuance at any time after the date the stockholder approval to increase our authorized common stock share count. Pursuant to the 2017 Rights Offering, which closed on November 28, 2017, the Company sold an aggregate of 10,000 units, resulting in total net proceeds to the Company of approximately $8.8 million. Based on the relevant authoritative accounting guidance, the warrants were equity classified at the issuance date. The warrants may be redeemed by the Company at $0.01 per warrant prior to their expiration if the Company’s common stock closes above $8.33 per share for 10 consecutive trading days. 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. The warrants are exercisable for an aggregate of 141,183 shares of the Company’s common stock at an exercise price of $39.93 per share for 30 months from the date of issuance and each share of Series C Preferred Stock is convertible into 25 shares of the Company's common stock. 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. 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. We recorded a deemed dividend within additional paid-in capital of $2.5 million for the quarter ended December 31, 2018, related to a beneficial conversion feature included in the issuance of our Series C Convertible Preferred Stock. Common Stock On April 11, 2017, we entered into the Underwriting Agreement with Maxim relating to the issuance and sale of 17,881 shares of our common stock. The price to the public in the offering was $550.00 per share. Maxim purchased the shares from us pursuant to the Underwriting Agreement at a price of $520.00 per share. The net proceeds to us from the offering were approximately $8.7 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by us. The offering closed on April 17, 2017. In addition, under the terms of the Underwriting Agreement, we granted Maxim a 45-day overallotment option to purchase up to 1,888 additional shares of common stock. On May 31, 2017, Maxim exercised their overallotment option and purchased 1,698 shares at $550.00 per share. The net proceeds to us were $0.8 million, after deducting underwriting costs and offering expenses payable by us. 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 a Purchase Agreement (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. The Company may direct Lincoln Park, at its sole discretion and subject to certain conditions, to purchase up to 5,000 shares of common stock on any business day but in no event will the amount of a single Regular Purchase (as defined in the Lincoln Park Purchase Agreement) exceed $1.0 million. The purchase price of shares of common stock related to the Regular Purchases will be based on the prevailing market prices of such shares at the time of sales. The Company’s sales of shares of common stock to Lincoln Park under the Lincoln Park Purchase Agreement are limited to the number of shares that would result in the beneficial ownership by Lincoln Park and its affiliates, at any single point in time, of no more than 4.99% of the then outstanding shares of the common stock. There are no trading volume requirements or restrictions under the Lincoln Park Purchase Agreement. There is no upper limit on the price per share that Lincoln Park must pay for common stock under a Regular Purchase or an accelerated purchase and in no event under an accelerated purchase will shares be sold to Lincoln Park on a day the closing price of the Company’s common stock is less than the floor price of $12.50 per share as set forth in the Lincoln Park Purchase Agreement. 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.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based Compensation	12. Stock-based Compensation In August 2014, we adopted the 2014 Equity Incentive Plan (the “2014 Plan”), which provides our employees, directors and consultants the opportunity to purchase our 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 our 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. On December 29, 2015, we 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, 2018, there are 3 shares and 18,957 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. 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, 2018 is as follows: Options Weighted Average Exercise Price Balance as of January 1, 2018 2,017 $ 5,962.50 Granted 2,346 $ 108.00 Expired (20 ) $ 38,553.50 Cancelled/forfeited (1,591 ) $ 296.50 Balance as of December 31, 2018 2,752 $ 4,003.50 Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Balance as of December 31, 2018 2,752 $ 4,003.50 7.90 $ — Vested and expected to vest at December 31, 2018 2,452 $ 4,447.00 7.78 $ — Exercisable at December 31, 2018 1,296 $ 8,099.50 6.59 $ — There were no stock options exercised in 2018 or 2017. The fair value of each option awarded during the year ended December 31, 2018 and 2017 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, 2018 2017 Expected term 7.1 years 6.6 years Risk-free interest rate 2.94 % 2.20 % Volatility 92.87 % 78.84 % Dividends — — Resulting weighted average grant date fair value $ 1.74 $ 1.05 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 we (a) have never declared or paid any dividends and (b) do not currently anticipate paying any cash dividends on our outstanding shares of common stock in the foreseeable future. Restricted Stock Awards Generally, restricted stock awards issued under the 2014 Plan are subject to a vesting period that coincides with the fulfillment of service requirements for each award and have a contractual term of 10 years. These awards are amortized to compensation expense over the estimated vesting period based upon the fair value of our common stock on the award date. The following summarizes the total compensation cost recognized for the stock options and restricted stock awards in the accompanying financial statements (in thousands): Years ended December 31, 2018 2017 Total compensation cost for share-based payment arrangements recognized in the statement of operations (net of tax of $0) $ 355 $ 753 As of December 31, 2018, the total compensation cost related to non-vested stock options and stock awards not yet recognized for all our plans is approximately $0.2 million, which is expected to be recognized as a result of vesting under service conditions over a weighted average period of 1.5 years. To settle stock options and restricted stock awards, we will issue new shares of our common stock. At December 31, 2018, we have an aggregate of 20,114 shares authorized and available to satisfy option exercises under our plans.

SCHEDULE II - VALUATION AND QUA

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2018
Valuation And Qualifying Accounts [Abstract]
SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS	For the years ended December 31, 2018 and 2017 (in thousands) Balance at beginning of year Additions (A) Deductions (B) Other (C) Balance at end of year Allowance for doubtful accounts Year ended December 31, 2018 $ — $ — $ — $ — $ — Year ended December 31, 2017 $ — $ — $ — $ — $ — (A) Includes charges to costs and expenses. (B) Deductions for uncollectible accounts receivable includes payments collected and devices recovered from customers. (C) Miscellaneous activity.

Basis of Presentation and New A

Basis of Presentation and New Accounting Standards	3 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation and New Accounting Standards	1. Basis of Presentation and New Accounting Standards Our accompanying unaudited consolidated condensed financial statements as of March 31, 2019 and for the three months ended March 31, 2019 and 2018 have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for annual financial statements. Our consolidated condensed balance sheet at December 31, 2018 has been derived from the audited financial statements at December 31, 2018, but does not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the financial position and results of operations of Plus Therapeutics, Inc., and our subsidiaries (collectively, the “Company”) have been included. Operating results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. These financial statements should be read in conjunction with the consolidated financial statements and notes therein included in our Annual Report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission (“SEC”) on March 29, 2019 as amended in our Form 8-K, filed with the SEC on September 10, 2019. Amendments to Certificate of Incorporation and Reverse Stock Split 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 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”. Additionally, the Company changed its trading symbol for its Series S warrants to “PSTVZ”. 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. There was no change in the Company’s Nasdaq ticker symbol, “PSTV,” as a result of the August 2019 Reverse Stock Split. 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 Amended and Restated 2004 Equity Incentive Plan, 2011 Employee Stock Purchase Plan, 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. All share and per share amounts have been adjusted retroactively to reflect the Reverse Stock Split and the August 2019 Reverse Stock Split for all periods presented. Recently Issued and Recently Adopted Accounting Pronouncements Recently Issued Accounting Pronouncements In February 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment Recently Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases

Use of Estimates

Use of Estimates	3 Months Ended
	Mar. 31, 2019
Use Of Estimates [Abstract]
Use of Estimates	2. 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. Our most significant estimates and critical accounting policies involve recognizing revenue, reviewing goodwill and intangible assets for impairment, determining the assumptions used in measuring share-based compensation expense, valuing warrants, measuring expense related to our in-process research and development acquisition, and valuing allowances for doubtful accounts and inventory reserves. 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.

Liquidity

Liquidity	3 Months Ended
	Mar. 31, 2019
Liquidity [Abstract]
Liquidity	3. Liquidity We incurred net losses of $3.2 million for the three months ended March 31, 2019, including $0.7 million from discontinued operations. We have an accumulated deficit of $417.5 million as of March 31, 2019. Additionally, we used net cash of $3.3 million to fund our operating activities for the three months ended March 31, 2019. These factors raise substantial doubt about the Company’s ability to continue as a going concern. Further, the Loan and Security Agreement (defined in Note 4), with Oxford Finance, LCC (“Oxford”), as further described in Note 4, requires maintenance of a minimum of $2.0 million in unrestricted cash and cash equivalents on hand to avoid an event of default under the Loan and Security Agreement. Based on our cash and cash equivalents on hand of approximately $3.9 million at March 31, 2019, the Company estimates that it will need to raise additional capital and/or obtain a waiver or restructure the Loan and Security Agreement in the near term to avoid defaulting under its $2.0 million minimum cash/cash equivalents covenant. To date, these operating losses have been funded primarily from outside sources of invested capital including our recently completed 2018 Rights Offering (defined in Note 3 below), our Lincoln Park Purchase Agreement (defined in Note 12) with Lincoln Park Capital Fund, LLC (“Lincoln Park”), the Loan and Security Agreement and gross profits. We have had, and we will continue to have, an ongoing need to raise additional cash from outside sources to fund our future clinical development programs and other operations. Our inability to raise additional cash would have a material and adverse impact on operations and would cause us to default on our loan. On June 1, 2018, we entered into a Sales Agreement with B. Riley FBR, Inc. (“B. Riley FBR”) to sell shares of our 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. Through March 31, 2019, we have sold a total of 0.2 million shares for proceeds of approximately $3.8 million through the ATM program. See Note 12 for further discussion on the ATM program. On July 25, 2018, we 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, immediately convertible into 168,478 shares of common stock and 7,059,150 warrants, with 50 warrants exercisable for one share of common stock at an exercise price of $39.93 per share, resulting in total net proceeds to the Company of approximately $5.7 million. On August 28, 2018, we received a written notice from The Nasdaq Stock Market LLC (“Nasdaq”) indicating that, based upon the closing bid price of our common stock for the prior 30 consecutive business days, we 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. We were 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 our common stock must have been at least $1.00 per share for a minimum of ten consecutive business days during the 180-day period. On September 21, 2018, we entered into a purchase agreement and a registration rights 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 and no shares were sold during the three months ended March 31, 2019. See Note 12 for further discussion on the Lincoln Park Agreement. We continue to seek additional capital through product revenues, strategic transactions, including extension opportunities under our awarded U.S. Department of Health and Human Service’s Biomedical Advanced Research and Development Authority (“BARDA”) contract, and from other financing alternatives. Without additional capital, current working capital and cash generated from sales will not provide adequate funding for research, sales and marketing efforts and product development activities at their current levels. If sufficient capital is not raised, we will at a minimum need to significantly reduce or curtail our research and development and other operations, and this would negatively affect our ability to achieve corporate growth goals. On April 24, 2019 the Company received $3.4 million of net cash proceeds related to the sale of the Company’s UK subsidiary, Cytori Ltd., and the Company’s 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 $2.5 million of net cash proceeds related to the sale of the Plus Therapeutics, K.K., 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 (See Note 13). Should we be unable to raise additional cash from outside sources, this would have a material adverse impact on our operations. The accompanying consolidated condensed 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.

Revenue Recognition

Revenue Recognition	3 Months Ended
	Mar. 31, 2019
Revenue Recognition [Abstract]
Revenue Recognition	6. Revenue Recognition Development Revenue We earn revenue for performing tasks under research and development agreements with governmental agencies like BARDA which is outside of the scope of the new revenue recognition guidance. Revenues derived from reimbursement of direct out-of-pocket expenses for research costs associated with government contracts are recorded as government contracts 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. We recognized $0.7 million in development revenue for the three months ended March 31, 2019, as compared to $0.9 million for the three months ended March 31, 2018. Concentration of Significant Customers After the sale of our Cell Therapy business, BARDA accounted for 100% of our revenue from continuing operations which are recognized for the three months ended March 31, 2019 and March 31, 2018 and accounted for 100% of total outstanding accounts receivable presented in the accompanying consolidated financial statements.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Inventories	7. Inventories Inventories consist primarily of research devices and supplies, and are carried at the lower of cost or net realizable value. Inventories had a net book value of approximately $107,000 as of December 31, 2018 and 2017.

Loss per Share

Loss per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Loss per Share	8. 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 to outstanding but unexercised options, multiple series of preferred stock, and warrants for all periods presented. We have excluded all potentially dilutive securities from the calculation of diluted loss per share attributable to common stockholders as of March 31, 2019 and 2018, as their inclusion would be antidilutive. Potentially dilutive common shares excluded from the calculations of diluted loss per share were 0.3 million as of March 31, 2019, which includes 0.2 million outstanding warrants and 2,676 options, 92,523 shares of preferred stock, and restricted stock awards. Potentially dilutive common shares excluded from the calculation of diluted loss per share were 46,858 as of March 31, 2018.

Commitments

Commitments	3 Months Ended
	Mar. 31, 2019
Commitments [Abstract]
Commitments	9. Commitments 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 March 31, 2019. The Company leases office and storage facilities and equipment under various operating and financing lease agreements. The initial terms of these leases range from 2 to 11 years and 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): March 31, 2019 Assets Operating $ 908 Financing 215 Total leased assets $ 1,123 Liabilities Current: Operating $ 215 Financing 130 Noncurrent: Operating 693 Financing 85 Total lease liabilities $ 1,123 The table below summarizes the Company’s lease costs from its Unaudited Consolidated Statement of Operations, and cash payments from its Unaudited Consolidated Statement of Cash Flows during the three months ended March 31, 2019 (in thousands, except years and rates): March 31, 2019 Lease expense: Operating lease expense $ 55 Finance lease expense: Depreciation of right-of-use assets 33 Interest expense on lease liabilities — Total lease expense $ 88 Cash payment information: Operating cash used for operating leases $ 55 Financing cash used for financing leases 28 Total cash paid for amounts included in the measurement of lease liabilities $ 83 Weighted-average remaining lease term (years) - operating leases 7.9 Weighted-average remaining lease term (years) - finance leases 1.8 Weighted-average discount rate - operating leases 8.0 % Weighted-average discount rate - finance leases 5.0 % The Company’s future minimum annual lease payments under operating and financing leases at March 31, 2019 are as follows in (thousands): Financing Operating Leases Leases Remaining 2019 $ 100 $ 527 2020 120 690 2021 7 668 2022 — 281 2023 — 100 Thereafter — 447 Total minimum lease payments $ 227 $ 2,713 Less: amount representing interest (13 ) ( 495 ) Present value of obligations under leases 214 2,218 Less: current portion (130 ) ( 700 ) Noncurrent lease obligations $ 84 $ 1,518 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 March 31, 2019, we have clinical research study obligations of $2.5 million, $1.8 million of which is expected to be paid within a year. Should the timing of the clinical trials change, the timing of the payment of these obligations would also change.

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2019
Loss Contingency [Abstract]
Contingencies	10. Contingencies 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. Management believes that any liability to us that may arise as a result of currently pending legal proceedings will not have a material adverse effect on our financial condition, liquidity, or results of operations as a whole. On August 31, 2018, we filed a Demand for Arbitration with the American Arbitration Association in San Diego, California, against Bimini Technologies LLC (“Bimini”) for fraud and breach of a Sale and Exclusive License/Supply Agreement made in 2013 under which Bimini licensed rights to the Company’s Standalone Fat Transplantation, including the Puregraft Product Line and associated trademarks. Our arbitration demand alleges that Bimini failed to make a $1.0 million milestone payment due to the Company after Bimini achieved $10.0 million in gross profits from the sale of the Company’s Puregraft product line, and Bimini deceived the Company about Bimini’s true gross profits figures. Our arbitration demand seeks that $1.0 million milestone payment, as well prejudgment interest and attorneys’ fees. On October 29, 2018 Bimini made the $1.0 million milestone payment. The parties subsequently entered into a settlement agreement resolving the claims in the Demand for Arbitration.

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2019
Investments All Other Investments [Abstract]
Financial Instruments	11. Financial Instruments We disclose fair value information about all financial instruments, whether or not recognized in the balance sheet, for which it is practicable to estimate fair value. The disclosures of estimated fair value of financial instruments at March 31, 2019, and as of December 31, 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. Further, based on the borrowing rates currently available for loans with similar terms, we believe the fair value of long-term debt approximates its carrying value. 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. The changes in the fair value of liability classified warrants are included in net income (loss) for the respective periods. 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.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events Sale of the UK Subsidiary and Certain Assets 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 BARDA. Both the Company and Lorem made customary representations, warranties and covenants in the Lorem Purchase Agreement, which is subject to termination by either the Company or Lorem upon the occurrence of specified events. 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. Sale of the Japanese Subsidiary and Certain Assets 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 have made customary representations, warranties and covenants in the Shirahama Purchase Agreement, which is subject to termination by either the Company or Mr. Shirahama upon the occurrence of specified events. 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. Accounting Assessment on the Sale of Assets The sale of the UK and Japanese Subsidiaries and related assets did not meet the criteria to be classified as held-for-sale as of March 31, 2019 as management did not have the authorization to commit to the sale until approval was obtained from the Board of Directors and Oxford in April 2019. The Company expects to recognize a loss on the disposal during the second quarter of 2019 however the amount has not yet been determined. The Company also performed a probability weighted undiscounted impairment assessment as of March 31, 2019 resulting in the conclusion that no impairment of the net assets included in the disposal group was required to be recognized as of March 31, 2019. Amendment to the Loan and Security Agreement On April 29, 2019, the Company entered into a seventh amendment, effective as of April 24, 2019 (the “Seventh Amendment”), to its existing Loan and Security Agreement with Oxford, pursuant to which, among other things, Oxford agreed to interest only payments starting May 1, 2019, with amortization payments resuming on May 1, 2020. The Seventh Amendment also requires that $1.7 million of the net proceeds received by the Company pursuant to the Lorem Purchase Agreement and $1.4 million of the net proceeds received by the Company pursuant to the Shirahama Purchase Agreement must be applied to prepay the loan. Additionally, the Seventh Amendment requires that the Company pay an amendment fee of $0.6 million at the earlier of the prepayment, maturity or acceleration of the loan.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Use of Estimates		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. Our most significant estimates and critical accounting policies involve recognizing revenue, reviewing goodwill and intangible assets for impairment, determining the assumptions used in measuring share-based compensation expense, valuing warrants, measuring expense related to our in-process research and development acquisition, and valuing allowances for doubtful accounts and inventory reserves. 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		Cash and cash equivalents We consider 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. We held no investments as of December 31, 2018 and 2017. We maintain our cash at insured financial institutions.
Restricted Cash		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 $0.7 million naming the landlord as a beneficiary as of December 31, 2018 and 2017, respectively.
Accounts Receivable		Accounts Receivable Accounts receivable are recorded at the invoiced amount and do not bear interest. The Company periodically assesses the collectability of accounts receivable on a specific customer basis considering factors such as evaluation of collectability, historical collection experience, the age of accounts receivable and other currently available evidence of the collectability, and records an allowance for doubtful accounts for the estimated uncollectible amount. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote.
Inventories		Inventories We periodically evaluate all inventories on hand and make appropriate provisions for any stock deemed excess or obsolete. Inventories related to our discontinued operations include the cost of material, labor, and overhead, and are stated at the lower of cost, determined on the first-in, first-out (FIFO) method, or net realizable value. Manufacturing costs resulting from lower than “normal” production levels are expensed as incurred.
Property and Equipment		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		Impairment We assess certain of our long-lived assets, such as property and equipment and intangible assets other than goodwill, 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. We recognized no impairment losses during any of the periods presented in these financial statements.
Goodwill and Intangibles		Goodwill and Intangibles Goodwill is reviewed for impairment annually or more frequently if indicators of impairment exist. We perform our impairment test annually during the fourth quarter. As the Company operates in a single operating segment and reporting unit, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test. If, after assessing qualitative factors, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. If deemed necessary, a two-step test is used to identify the potential impairment and to measure the amount of goodwill impairment, if any. The first step is to compare the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill is considered not impaired; otherwise, there is an indication that goodwill may be impaired and the amount of the loss, if any, is measured by performing step two. Under step two, the impairment loss, if any, is measured by comparing the implied fair value of the reporting unit goodwill with the carrying amount of goodwill. We experienced significant volatility in our share price during the year. During Q3 2018 and Q4 2018, our stock price significantly declined in comparison to the corresponding previous quarters. We performed a valuation of our single reporting unit as of September 30, 2018 (and as updated for the annual test during the fourth quarter in 2018). Based upon the results of our valuation, management concluded that the fair value of the reporting unit exceeded its carrying value. We determined that a blending of the income approach and an option pricing model back-solve was a reasonable approximation of the fair value of the reporting unit. Additionally, a further reduction in our market capitalization could be an indicator of impairment. Given the volatility of our stock price a continued decline in market capitalization could result in an impairment of our goodwill. There was no change in our goodwill balance from December 31, 2017 to December 31, 2018. Separable intangible assets related to our discontinued operations that have finite useful lives are amortized over their respective useful lives.
Warrant Liability		Warrant Liability Warrants with exercise price reset features (down-round protection) are accounted for as liabilities, with changes in the fair value included in net loss until they are either exercised or expire. In connection with the 2018 Rights Offering, in July 2018, the Company issued Series C Convertible Preferred Stock, immediately convertible into common stocks and warrants. The warrants may be redeemed by the Company at $0.50 per warrant prior to their expiration if the Company’s common stock closes above $181.50 per share, The warrants are not traded in an active securities market, and as such the estimated the fair value as of December 31, 2018 was determined by using an option pricing model with the following assumptions: As of December 31, 2018 As of July 25, 2018 (inception date) Common stock market price $ 14.50 $ 36.00 Risk-free interest rate 2.48 % 2.70 % Expected volatility 125 % 112 % Resulting fair value (per warrant) $ 6.50 $ 22.50 Expected term 2.1 years 2.5 years Expected volatility was computed using daily pricing observations of traded shares of Plus for recent periods that correspond to the expected term of the warrants. We believe this method produces an estimate that is representative of our expectations of future volatility over the expected term of these warrants. We currently have 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, most significantly the assumption with regards to future equity issuances and its impact to the down-round protection feature. Significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement. Refer to Note 4 for a discussion of the change in our Level 3 warrant liability value.
Revenue Recognition		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. We recognized $3.0 million and $3.7 million in BARDA revenue for the years ended December 31, 2018 and 2017, respectively. Concentration of Significant Customers After the sale of our Cell Therapy business, BARDA accounted for 100% of our revenue from continuing operations which are recognized for the year ended December 31, 2018 and 2017. BARDA also accounted for 100% of total outstanding accounts receivable presented in the accompanying consolidated financial statements.
Research and Development		Research and Development Research and development expenditures, which are charged to operations in the period incurred, include design, development, testing and enhancement of our product candidates, 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 $2.7 million and $3.5 million of qualified expenses that were incurred for the years ended December 31, 2018 and 2017, related to our government contract with BARDA.
Deferred Financing Costs and Other Debt-Related Costs		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 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, 2018 and 2017, 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		Share-Based Compensation We recognize 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. We estimate 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 we do 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		Segment Information For the years ended December 31, 2018 and 2017, the Company is managed as a single operating segment, therefore we report our results in one operating segment.
Loss Per Share		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 and warrants for all periods presented. We have excluded all potentially dilutive securities, including unvested performance-based restricted stock, from the calculation of diluted loss per share attributable to common stockholders for the years ended December 31, 2018 and 2017, as their inclusion would be antidilutive. Potentially dilutive securities excluded from the calculations of diluted loss per share were 0.3 million as of December 31, 2018, which includes 0.2 million outstanding warrants and 2,753 options, 94,589 of preferred stocks, and restricted stock awards. Potentially dilutive securities excluded from the calculations of diluted loss per share were 9,458 as of December 31, 2017.
Recently Issued and Recently Adopted Accounting Pronouncements	Recently Issued and Recently Adopted Accounting Pronouncements Recently Issued Accounting Pronouncements In February 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment Recently Adopted Accounting Pronouncements Leases	Recently Issued and Recently Adopted Accounting Pronouncements Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases 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. We are currently evaluating the impact that this standard will have on our consolidated financial statements. Recently Adopted Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers In November 2016, the FASB issued ASU 2016-18, Restricted Cash
Basis of Presentation and New Accounting Standards	Our accompanying unaudited consolidated condensed financial statements as of March 31, 2019 and for the three months ended March 31, 2019 and 2018 have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for annual financial statements. Our consolidated condensed balance sheet at December 31, 2018 has been derived from the audited financial statements at December 31, 2018, but does not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the financial position and results of operations of Plus Therapeutics, Inc., and our subsidiaries (collectively, the “Company”) have been included. Operating results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. These financial statements should be read in conjunction with the consolidated financial statements and notes therein included in our Annual Report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission (“SEC”) on March 29, 2019 as amended in our Form 8-K, filed with the SEC on September 10, 2019.

Basis of Presentation and New_2

Basis of Presentation and New Accounting Standards (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Recently Issued and Recently Adopted Accounting Pronouncements	Recently Issued and Recently Adopted Accounting Pronouncements Recently Issued Accounting Pronouncements In February 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment Recently Adopted Accounting Pronouncements Leases	Recently Issued and Recently Adopted Accounting Pronouncements Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases 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. We are currently evaluating the impact that this standard will have on our consolidated financial statements. Recently Adopted Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers In November 2016, the FASB issued ASU 2016-18, Restricted Cash

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions	The warrants are not traded in an active securities market, and as such the estimated the fair value as of March 31, 2019 was determined by using an option pricing model with the following assumptions: As of March 31, 2019 As of December31, 2018 Expected term 1.8 years 2.1 years Common stock market price $ 13.00 $ 14.50 Risk-free interest rate 2.38 % 2.48 % Expected volatility 128 % 125 % Resulting fair value (per warrant) $ 5.00 $ 6.50	The warrants are not traded in an active securities market, and as such the estimated the fair value as of December 31, 2018 was determined by using an option pricing model with the following assumptions: As of December 31, 2018 As of July 25, 2018 (inception date) Common stock market price $ 14.50 $ 36.00 Risk-free interest rate 2.48 % 2.70 % Expected volatility 125 % 112 % Resulting fair value (per warrant) $ 6.50 $ 22.50 Expected term 2.1 years 2.5 years

Discontinued Operations (Tables

Discontinued Operations (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Discontinued Operations And Disposal Groups [Abstract]
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 will be finalized during the fourth quarter of 2019 (in thousands): Consideration received $ 7,000 Transaction costs (1,161 ) Net cash proceeds 5,839 Less: Carrying value of business and assets sold 12,145 Net loss on sale of business $ 6,306	The following table summarizes the calculation of the loss on sale of the cell therapy business, which will be finalized during the fourth quarter of 2019 (in thousands): Consideration received $ 7,000 Transaction costs (1,161 ) Net cash proceeds 5,839 Less: Carrying value of business and assets sold 12,145 Net loss on sale of business $ 6,306
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 consisted of the following: March 31, 2019 December 31, 2018 Assets Current assets held for sale: Accounts receivable, net $ 202 $ 108 Inventory, net 2,896 2,841 Other current assets 356 328 Long-term assets held for sale: Property and equipment, net 223 260 Operating lease right-of-use assets 1,030 — Other noncurrent assets 1,787 1,866 Goodwill 3,550 3,550 Intangible assets, net 5,645 5,957 Total assets $ 15,689 $ 14,910 Liabilities Current liabilities held for sale: Accounts payable and accrued liabilities $ 495 $ 580 Operating lease liabilities 355 — Noncurrent liabilities held for sale: Other noncurrent liabilities 70 78 Operating lease liabilities 740 — Deferred revenues 142 167 Total liabilities held for sale $ 1,802 $ 825 The following table summarizes the results of discontinued operations for the periods presented (in thousands): Three months ended March 31, 2019 2018 Product revenue $ 703 $ 731 Cost of revenues 659 579 Gross profit 44 152 Operating expenses: Research and development 420 1,104 Sales and marketing 314 384 General and administrative 145 146 Total operating expenses 879 1,634 Operating loss (835 ) (1,482 ) Other income (expense) 149 352 Loss from discontinued operations $ (686 ) $ (1,130 ) Included in the statement of cash flows are the following non-cash adjustments related to the discontinued operations (in thousands): For the three months ended March 31, 2019 2018 Depreciation and amortization $ 344 $ 393 Provision for excess inventory $ — $ 326 Loss on asset disposal $ — $ 22	Assets and liabilities related to discontinued operations or held for sale consisted of the following: December 31, 2018 December 31, 2017 Assets Current assets held for sale: Accounts receivable, net $ 108 $ 15 Inventory, net 2,841 3,076 Other current assets 328 531 Long-term assets held for sale: Property and equipment, net 260 727 Other noncurrent assets 1,866 2,528 Goodwill 3,550 3,550 Intangible assets, net 5,957 7,207 Total assets $ 14,910 $ 17,634 Liabilities Current liabilities held for sale: Accounts payable and accrued liabilities $ 580 $ 584 Noncurrent liabilities held for sale: Other noncurrent liabilities 78 107 Deferred revenues 167 94 Total liabilities held for sale $ 825 $ 785 The following table summarizes the results of discontinued operations for the periods presented (in thousands): Year ended December 31, 2018 2017 Product revenue $ 2,671 $ 2,689 License revenue 1,000 — Total revenues 3,671 2,689 Cost of revenues 2,373 2,543 Gross profit 1,298 146 Operating expenses: Research and development 3,099 6,605 Sales and marketing 1,375 2,252 General and administrative 760 894 Total operating expenses 5,234 9,751 Operating loss (3,936 ) (9,605 ) Other income (expense) 180 13 Loss from discontinued operations $ (3,756 ) $ (9,592 ) 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, 2018 2017 Depreciation and amortization $ 1,625 $ 1,630 Provision for excess inventory $ 463 $ 340 (Loss) gain $ (36 ) $ 40 The changes in the carrying amounts of finite-life intangible assets related to our discontinued operations for the years ended December 31, 2018 and 2017 are as follows (in thousands): December 31, 2018 December 31, 2017 Intangibles, net: Beginning balance $ 7,207 $ 8,447 Increase — — Amortization (1,250 ) (1,240 ) Ending balance $ 5,957 $ 7,207

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Change in Level 3 Warrant Liability Value	The following table summarizes the change in our Level 3 warrant liability value (in thousands): Warrant liability March 31, 2019 December 31, 2018 Beginning balance $ 916 $ 3,149 Change in fair value (210 ) (2,233 ) Ending balance $ 706 $ 916	The following table summarizes the change in our Level 3 warrant liability value (in thousands): Years ended December 31, Warrant liability 2018 2017 Beginning balance $ 3,149 $ — Change in fair value (2,233 ) — Ending balance $ 916 $ —
Fair Value and Carrying Value of Long-term Debt		At December 31, 2018 and 2017, the aggregate fair value and the carrying value of the Company’s long-term debt were as follows (in thousands): December 31, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value Debt $ 14,043 $ 14,202 $ 13,427 $ 13,624

Asset Purchase Agreement with_2

Asset Purchase Agreement with Azaya Therapeutics (Tables)	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
Summery Of Purchase Price Allocation On Fair Value Basis To Identifiable Net Assets	The total consideration was allocated on a relative fair value basis to the assets acquired, as follows (in thousands): February 15, 2017 Tangible assets $ 2,586 Intangible assets 1,686 Total assets $ 4,272 Accounts payable $ 1,796 Fair value of the common stock issued 2,311 Transaction costs 165 Total consideration $ 4,272

Composition of Certain Financ_2

Composition of Certain Financial Statement Captions (Tables)	12 Months Ended
	Dec. 31, 2018
Composition Of Certain Financial Statement Captions [Abstract]
Other Current Assets	As of December 31, 2018 and 2017, other current assets were comprised of the following (in thousands): December 31, 2018 2017 Prepaid services, current $ 166 $ 121 Prepaid insurance 564 556 Other receivables 55 103 $ 785 $ 780
Property and Equipment, net	As of December 31, 2018 and 2017, property and equipment, net, were comprised of the following (in thousands): December 31, 2018 2017 Office and computer equipment $ 1,279 $ 1,041 Leasehold improvements 1,682 1,686 Property and equipment – gross 2,961 2,727 Less accumulated depreciation (662 ) (402 ) Property and equipment – net $ 2,299 $ 2,325
Other Assets	As of December 31, 2018 and 2017, other assets were comprised of the following (in thousands December 31, 2018 2017 Deposits $ 39 $ 42 $ 39 $ 42
Accounts Payable and Accrued Expenses	As of December 31, 2018 and 2017, accounts payable and accrued expenses were comprised of the following (in thousands): December 31, 2018 2017 Accrued expenses $ 824 $ 1,182 Accounts payable 721 1,297 Accrued payroll and bonus 423 750 Accrued legal fees 186 509 Accrued vacation 192 64 Accrued R&D studies 230 285 Other current liabilities 201 119 $ 2,777 $ 4,206

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Future Minimum Debt and Lease Payments	As of December 31, 2018, the future contractual principal and final fee payments on all of our debt and capital lease obligations are as follows (as thousands): Years Ending December 31, 2019 $ 8,653 2020 6,090 Total $ 14,743 Reconciliation of Face Value to Book Value as of December 31, 2018 Total debt and lease obligations, including final payment fee (Face Value) $ 14,743 Less: Debt discount (541 ) Total obligation $ 14,202
Payment on Lease Office and Manufacturing Space [Member]
Future Minimum Debt and Lease Payments	As of December 31, 2018, we have contractual lease obligations to make payments on leases of office and manufacturing space as follows: Years Ending December 31, Obligation 2019 $ 1,282 2020 638 2021 638 2022 192 Total $ 2,750

Term Loan Obligations (Tables)

Term Loan Obligations (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Term Loan Outstanding	Additional details relating to the outstanding Term Loan as of December 31, 2018 and 2017 are presented in the following table (in thousands): 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 Year ended December 31, 2017 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 2017, which reflects interest only ** 3 month LIBOR rate with a floor of 1% plus 7.95% *** Monthly payment as of December 2018, which reflects interest only
Future Minimum Debt and Lease Payments	As of December 31, 2018, the future contractual principal and final fee payments on all of our debt and capital lease obligations are as follows (as thousands): Years Ending December 31, 2019 $ 8,653 2020 6,090 Total $ 14,743 Reconciliation of Face Value to Book Value as of December 31, 2018 Total debt and lease obligations, including final payment fee (Face Value) $ 14,743 Less: Debt discount (541 ) Total obligation $ 14,202

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Components of Income/(Loss) Before Income Tax Provision (Benefit)	The components of income/(loss) before income tax provision (benefit) from continuing operations as of December 31, 2018 and 2017 are as follows (in thousands): 2018 2017 U.S. $ (8,346 ) $ (12,230 ) Foreign (507 ) (843 ) $ (8,853 ) $ (13,073 )
Reconciliation of Total Income Tax Provision	A reconciliation of the total income tax provision tax rate from continuing operations to the statutory federal income tax rates of 21% and 34% for the years ended December 31, 2018 and 2017, respectively, is as follows: 2018 2017 Income tax expense (benefit) at federal statutory rate (21.0 )% (34.0 )% Income tax expense (benefit) at state statutory rate (8.2 )% (6.7 )% Change in valuation allowance 35.8 % (324.5 )% Change in state rate (0.1 )% (1.5 )% Permanent interest adjustments 0.7 % 0.4 % Stock compensation 1.8 % 5.2 % Research credit (1.4 )% (1.9 )% Foreign rate differential — 350.4 % NOLs expiring and adjustments to NOL — 12.1 % Mark to market adjustment (5.3 )% — Other, net (2.3 )% 0.5 % 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, 2018 and 2017 are as follows (in thousands): 2018 2017 Deferred tax assets: Allowances and reserves $ 270 $ 140 Accrued expenses 122 154 Stock based compensation 996 1,065 Net operating loss carryforwards 91,197 87,426 Income tax credit carryforwards 8,671 8,587 Property and equipment, principally due to differences in depreciation 548 514 Other, net 38 45 101,842 97,931 Valuation allowance (101,091 ) (97,089 ) Total deferred tax assets, net of allowance 751 842 Deferred tax liabilities: Intangibles assets (751 ) (842 ) Total deferred tax liability (751 ) (842 ) 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, 2018 and 2017 (in thousands): 2018 2017 Unrecognized Tax Benefits – Beginning $ 2,157 $ 2,062 Gross increases – tax positions in prior period 1 — Gross decreases – tax positions in prior period (3 ) — Gross increase – current-period tax positions 61 95 Unrecognized Tax Benefits – Ending $ 2,216 $ 2,157

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Option Activity	A summary of activity for the year ended December 31, 2018 is as follows: Options Weighted Average Exercise Price Balance as of January 1, 2018 2,017 $ 5,962.50 Granted 2,346 $ 108.00 Expired (20 ) $ 38,553.50 Cancelled/forfeited (1,591 ) $ 296.50 Balance as of December 31, 2018 2,752 $ 4,003.50
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, 2018 2,752 $ 4,003.50 7.90 $ — Vested and expected to vest at December 31, 2018 2,452 $ 4,447.00 7.78 $ — Exercisable at December 31, 2018 1,296 $ 8,099.50 6.59 $ —
Weighted-average Assumptions	The fair value of each option awarded during the year ended December 31, 2018 and 2017 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, 2018 2017 Expected term 7.1 years 6.6 years Risk-free interest rate 2.94 % 2.20 % Volatility 92.87 % 78.84 % Dividends — — Resulting weighted average grant date fair value $ 1.74 $ 1.05
Compensation Cost Recognized for Stock Options and Restricted Stock Awards	The following summarizes the total compensation cost recognized for the stock options and restricted stock awards in the accompanying financial statements (in thousands): Years ended December 31, 2018 2017 Total compensation cost for share-based payment arrangements recognized in the statement of operations (net of tax of $0) $ 355 $ 753

Commitments (Tables)

Commitments (Tables)	3 Months Ended
	Mar. 31, 2019
Commitments [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): March 31, 2019 Assets Operating $ 908 Financing 215 Total leased assets $ 1,123 Liabilities Current: Operating $ 215 Financing 130 Noncurrent: Operating 693 Financing 85 Total lease liabilities $ 1,123
Summary of Lease Costs	The table below summarizes the Company’s lease costs from its Unaudited Consolidated Statement of Operations, and cash payments from its Unaudited Consolidated Statement of Cash Flows during the three months ended March 31, 2019 (in thousands, except years and rates): March 31, 2019 Lease expense: Operating lease expense $ 55 Finance lease expense: Depreciation of right-of-use assets 33 Interest expense on lease liabilities — Total lease expense $ 88 Cash payment information: Operating cash used for operating leases $ 55 Financing cash used for financing leases 28 Total cash paid for amounts included in the measurement of lease liabilities $ 83 Weighted-average remaining lease term (years) - operating leases 7.9 Weighted-average remaining lease term (years) - finance leases 1.8 Weighted-average discount rate - operating leases 8.0 % Weighted-average discount rate - finance leases 5.0 %
Summary of Future Minimum Annual Lease Payments under Operating and Financing Leases	The Company’s future minimum annual lease payments under operating and financing leases at March 31, 2019 are as follows in (thousands): Financing Operating Leases Leases Remaining 2019 $ 100 $ 527 2020 120 690 2021 7 668 2022 — 281 2023 — 100 Thereafter — 447 Total minimum lease payments $ 227 $ 2,713 Less: amount representing interest (13 ) ( 495 ) Present value of obligations under leases 214 2,218 Less: current portion (130 ) ( 700 ) Noncurrent lease obligations $ 84 $ 1,518

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Stockholders Equity Note [Abstract]
Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions	The warrants are not traded in an active securities market, and as such the estimated the fair value as of March 31, 2019 was determined by using an option pricing model with the following assumptions: As of March 31, 2019 As of December31, 2018 Expected term 1.8 years 2.1 years Common stock market price $ 13.00 $ 14.50 Risk-free interest rate 2.38 % 2.48 % Expected volatility 128 % 125 % Resulting fair value (per warrant) $ 5.00 $ 6.50	The warrants are not traded in an active securities market, and as such the estimated the fair value as of December 31, 2018 was determined by using an option pricing model with the following assumptions: As of December 31, 2018 As of July 25, 2018 (inception date) Common stock market price $ 14.50 $ 36.00 Risk-free interest rate 2.48 % 2.70 % Expected volatility 125 % 112 % Resulting fair value (per warrant) $ 6.50 $ 22.50 Expected term 2.1 years 2.5 years
Summary of Change in Level 3 Warrant Liability Value	The following table summarizes the change in our Level 3 warrant liability value (in thousands): Warrant liability March 31, 2019 December 31, 2018 Beginning balance $ 916 $ 3,149 Change in fair value (210 ) (2,233 ) Ending balance $ 706 $ 916	The following table summarizes the change in our Level 3 warrant liability value (in thousands): Years ended December 31, Warrant liability 2018 2017 Beginning balance $ 3,149 $ — Change in fair value (2,233 ) — Ending balance $ 916 $ —

Organization and Operations - A

Organization and Operations - Additional Information (Details)	Aug. 05, 2019$ / sharesshares	Apr. 25, 2019USD ($)	Apr. 24, 2019USD ($)	Sep. 21, 2018USD ($)	Aug. 28, 2018$ / shares	Jul. 25, 2018USD ($)$ / sharesshares	Jun. 01, 2018USD ($)	May 23, 2018$ / sharesshares	Nov. 28, 2017USD ($)$ / sharesshares	Sep. 05, 2017$ / shares	May 31, 2017USD ($)$ / sharesshares	Apr. 11, 2017USD ($)$ / sharesshares	Mar. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Mar. 31, 2018USD ($)shares	Dec. 31, 2018USD ($)$ / sharesshares	Mar. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)Subsidiary$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	May 24, 2018shares	Nov. 27, 2017shares	Dec. 31, 2016USD ($)shares
Basis Of Presentation And New Accounting Standards [Line Items]
Number of wholly-owned subsidiaries | Subsidiary																		5
Reverse stock split of common stock								0.1
Common stock, par value (in dollars per share) | $ / shares								$ 0.001					$ 0.001	$ 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	100,000,000	100,000,000	100,000,000
Common stock, shares issued (in shares)								61,600,000					438,116	296,609		296,609	438,116	296,609	115,651	6,200,000
Common stock, shares outstanding (in shares)								61,600,000					438,116	296,609		296,609	438,116	296,609	115,651	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	5,000,000
Common stock, reverse stock split, fractional shares issued								0
Net loss | $													$ 3,150,000		$ 4,409,000			$ 12,634,000	$ 22,686,000
Net loss from discountinued operations | $													686,000		1,130,000			3,756,000	9,592,000
Accumulated deficit | $													(417,533,000)	$ (414,383,000)		$ (414,383,000)	$ (417,533,000)	(414,383,000)	(401,749,000)
Net cash used in operating activities | $													$ (3,270,000)		(4,119,000)			$ (11,975,000)	(18,128,000)
Substantial doubt about going concern, description													These factors raise substantial doubt about the Company’s ability to continue as a going concern.					These factors raise substantial doubt about the Company’s ability to continue as a going concern
Net proceeds excess receives from unrestricted cash | $																		$ 4,000,000
Cash and cash equivalents | $													$ 3,872,000	5,261,000		5,261,000	3,872,000	5,261,000	9,550,000			$ 12,600,000
Minimum cash/cash equivalents covenant | $													2,000,000	$ 2,000,000		$ 2,000,000	$ 2,000,000	2,000,000
Common stock issued (in shares)						6,723			10,000
Proceeds from sale of common stock, net | $													1,919,000		(150,000)			0	0
Proceeds from issuance warrants | $						$ 5,700,000			$ 8,800,000
Date from which warrants are exercisable									May 18, 2018
Common stock issued, value | $													$ 1,873,000		$ 27,000			1,624,000	12,716,000
Series B Convertible Preferred Stock [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of shares callable by warrants (in shares)									360,000
Preferred stock, shares authorized (in shares)																					10,000
Common stock issued (in shares)									60,000
Common stock issued, value | $																			$ 8,767,000
Series C Convertible Preferred Stock [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of shares callable by warrants (in shares)						7,059,150
Preferred stock, shares authorized (in shares)						7,000
Number of convertible shares converted into common stock (in shares)						168,478
Common stock issued, value | $																		$ 3,041,000
Nasdaq Stock Market LLC [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of consecutive business days no longer able to meet the required closing bid price of common stock					30 days					30 days
Minimum bid price of common stock required for Nasdaq listing rule | $ / shares					$ 1					$ 1
Grace period provided with minimum bid price for Nasdaq listing rule					180 days					180 days
Grace date for minimum bid price requirement for Nasdaq listing					Feb. 25, 2019					Mar. 5, 2018
Common stock minimum bid price required to regain compliance | $ / shares					$ 1					$ 1
Number of consecutive business days required to regain compliance					10 days					10 days
Additional grace period provided with minimum bid price to regain compliance					180 days					180 days
Date to regain compliance after meeting continued listing requirement					Aug. 26, 2019					Sep. 4, 2018
Description of compliance with minimum bid price requirement					We were 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.													We were 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.
Common Stock [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock, shares outstanding (in shares)													438,116	296,609	123,227	296,609	438,116	296,609	115,651			43,416
Number of shares callable by warrants (in shares)						50			36,000
Common stock issued (in shares)						6,723			10,000				139,855		201			92,169	24,474
Share issued, price per share | $ / shares												$ 550
Warrant exercise price (in dollars per share) | $ / shares						$ 39.93			$ 166.65
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock issued (in shares)																1,584	200,000
Proceeds from sale of common stock, net | $																$ 1,700,000	$ 3,800,000
Common Stock [Member] | Lincoln Park [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock issued (in shares)													0	12,802
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] | Series B Convertible Preferred Stock [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of convertible shares converted into common stock (in shares)															7,375			7,921	45,413
Common Stock [Member] | Series C Convertible Preferred Stock [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Number of convertible shares converted into common stock (in shares)													1,652					80,868
Common Stock [Member] | Maxim Group LLC [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Common stock issued (in shares)											1,698	17,881
Share issued, price per share | $ / shares											$ 550	$ 520
Proceeds from sale of common stock, net | $											$ 800,000	$ 8,700,000
Closing of offering date												Apr. 17, 2017
Number of days granted as option to purchase additional shares of common stock to underwriter												45 days
Additional shares of common stock												1,888
Minimum [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Unrestricted cash and cash equivalents | $													$ 2,000,000	$ 2,000,000		$ 2,000,000	$ 2,000,000	$ 2,000,000
Maximum [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Unrestricted gross cash proceeds required to extend interest-only period | $																		$ 7,500,000
Maximum [Member] | Common Stock [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
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
Subsequent Event [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Reverse stock split of common stock	0.02
Common stock, par value (in dollars per share) | $ / shares	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000
Common stock, reverse stock split, fractional shares issued	0
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.
Reverse Stock Split Effective Date For Trading Purposes	Aug. 6, 2019
Sale of UK Subsidiary and Certain Assets [Member] | Loan and Security Agreement [Member] | Subsequent Event [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Cash proceeds from sale of subsidiary | $			$ 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] | Subsequent Event [Member]
Basis Of Presentation And New Accounting Standards [Line Items]
Cash proceeds from sale of subsidiary | $		$ 3,000,000
Payments for principal, interest and fees | $		$ 1,400,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)$ / sharesshares	Mar. 31, 2018shares	Dec. 31, 2018USD ($)Segment$ / sharesshares	Dec. 31, 2017USD ($)Segmentshares	Jul. 25, 2018USD ($)	Dec. 31, 2016USD ($)
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents investments with original maturities			$ 0	$ 0
Impairment loss			0	0
Goodwill	$ 372,000		372,000	372,000
Qualifying expenditures related to research			2,700,000	3,500,000
Interest or penalties related to income tax matters			$ 0	$ 0
Number of operating segment | Segment			1	1
Dilutive securities excluded from the calculations of diluted loss per share (in shares) | shares	300,000	46,858	300,000	9,458
Restricted cash	$ 40,000		$ 40,000	$ 675,000		$ 400,000
Cash, cash equivalents	$ 3,872,000		$ 5,261,000	9,550,000		$ 12,600,000
Outstanding Warrants [Member]
Summary Of Significant Accounting Policies [Line Items]
Dilutive securities excluded from the calculations of diluted loss per share (in shares) | shares	200,000		200,000
Options and Restricted Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Dilutive securities excluded from the calculations of diluted loss per share (in shares) | shares			2,753
Preferred Stock and Restricted Stock Awards [Member]
Summary Of Significant Accounting Policies [Line Items]
Dilutive securities excluded from the calculations of diluted loss per share (in shares) | shares	92,523		94,589
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	100.00%	100.00%
Barda Contract | Development
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized			$ 3,000,000	3,700,000
2018 Rights Offering [Member]
Summary Of Significant Accounting Policies [Line Items]
Redemption price of warrant prior to expiration | $ / shares	$ 0.50		$ 0.50
Common stock price per share for warrant redemption | $ / shares	$ 181.50		$ 181.50
Number of consecutive trading days for warrant redemption	20 days		20 days
Warrants liability fair value	$ 1,500,000		$ 900,000		$ 3,100,000
Barda Contract
Summary Of Significant Accounting Policies [Line Items]
Goodwill			$ 0	$ 0
Barda Contract | Customer Concentration Risk [Member] | Revenue, Product and Service Benchmark [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage			100.00%	100.00%
Barda Contract | 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	$ 700,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions (Details)	Mar. 31, 2019$ / shares	Dec. 31, 2018$ / shares	Jul. 25, 2018$ / shares
Measurement Input, Expected Term
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants expected term	1 year 9 months 18 days	2 years 1 month 6 days	2 years 6 months
Measurement Input, Share Price
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	13	14.50	36
Measurement Input, Risk Free Interest Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	0.0238	0.0248	0.0270
Measurement Input, Price Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	1.28	1.25	1.12
Measurement Input Resulting Fair Value Per Warrant
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants measurement input	5	6.50	22.50

Discontinued Operations - Summa

Discontinued Operations - Summary of Business Consideration to Calculation of the Loss on Sale (Details) - USD ($) $ in Thousands	Apr. 25, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net loss on sale of business		$ 22	$ (36)	$ 40
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	(1,161)
Net cash proceeds	5,839
Carrying value of business and assets sold	12,145
Net loss on sale of business	$ 6,306

Discontinued Operations - Sum_2

Discontinued Operations - Summary of Assets and Liabilities Related to Discontinued Operation Held for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noncurrent liabilities held for sale:
Total liabilities held for sale	$ 952	$ 245	$ 201
Held for Sale [Member]
Current assets held for sale:
Accounts receivable, net	202	108	15
Inventory, net	2,896	2,841	3,076
Other current assets	356	328	531
Long-term assets held for sale:
Property and equipment, net	223	260	727
Other noncurrent assets	1,787	1,866	2,528
Goodwill	3,550	3,550	3,550
Intangible assets, net	5,645	5,957	7,207
Operating lease right-of-use assets	1,030
Total assets	15,689	14,910	17,634
Current liabilities held for sale:
Accounts payable and accrued liabilities	495	580	584
Operating lease liabilities	355
Noncurrent liabilities held for sale:
Other noncurrent liabilities	70	78	107
Deferred revenues	142	167	94
Operating lease liabilities	740
Total liabilities held for sale	$ 1,802	825	$ 785
Held for Sale [Member] | Previously Reported
Current assets held for sale:
Inventory, net		$ 2,840

Discontinued Operations - Sum_3

Discontinued Operations - Summary of Operating Results Related to Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Discontinued Operations And Disposal Groups [Abstract]
Product revenue	$ 703	$ 731	$ 2,671	$ 2,689
License revenue			1,000
Total revenues			3,671	2,689
Cost of revenues	659	579	2,373	2,543
Gross profit	44	152	1,298	146
Operating expenses:
Research and development	420	1,104	3,099	6,605
Sales and marketing	314	384	1,375	2,252
General and administrative	145	146	760	894
Total operating expenses	879	1,634	5,234	9,751
Operating loss	(835)	(1,482)	(3,936)	(9,605)
Other income (expense)	149	352	180	13
Loss from discontinued operations	$ (686)	$ (1,130)	$ (3,756)	$ (9,592)

Discontinued Operations - Sum_4

Discontinued Operations - Summary of Non-Cash Adjustments Related to Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Discontinued Operations And Disposal Groups [Abstract]
Depreciation and amortization	$ 344	$ 393	$ 1,625	$ 1,630
Provision for excess inventory	$ 0	326	463	340
(Loss) gain on asset disposal		$ 22	$ (36)	$ 40

Discontinued Operations - Sum_5

Discontinued Operations - Summary of Significant Accounting Policies - Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Intangibles, net:
Intangibles, net, Beginning balance	$ 7,207	$ 8,447
Intangibles, net, Amortization	(1,250)	(1,240)
Intangibles, net, Ending balance	$ 5,957	$ 7,207

Fair Value - Summary of Change

Fair Value - Summary of Change in Level 3 Warrant Liability Value (Details) - Warrant Liability [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Warrant liability
Beginning balance	$ 916	$ 3,149
Change in fair value	(210)	(2,233)
Ending balance	$ 706	$ 916

Fair Value - Fair Value and Car

Fair Value - Fair Value and Carrying Value of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	$ 14,043	$ 13,427
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt	$ 14,202	$ 13,624

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt discount	$ 0.6	$ 0.4

Asset Purchase Agreement with_3

Asset Purchase Agreement with Azaya Therapeutics - Additional Information (Details) - Assets Purchased from Azaya Therapeutics, Inc. [Member]	Feb. 15, 2017USD ($)CandidateEmployeeshares	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Obligation to pay on existing payables assumed	$ 1,796,000
Total consideration	4,272,000
Fair value of the common stock issued	2,311,000
Assumed liabilities	1,800,000
Acquisition costs	200,000
Asset Purchase Agreement
Business Acquisition [Line Items]
Book value of tangible assets acquired	$ 3,000,000
Common stock, shares issued | shares	117,325
Common stock, shares issued after closing date | shares	87,994
Common stock deposited in escrow | shares	29,331
Obligation to pay on existing payables assumed	$ 1,800,000
Existing payables, paid during the period		$ 1,800,000
Number of employees | Employee	0
Maximum earn-out payment obligations	$ 100,000,000
Aggregate payment obligation threshold limit	$ 50,000,000
Percentage of net sales deemed for purposes of calculating payments	50.00%
Asset Purchase Agreement | IPR&D [Member]
Business Acquisition [Line Items]
Number of drug candidates acquired | Candidate	2

Asset Purchase Agreement with_4

Asset Purchase Agreement with Azaya Therapeutics - Summery of Purchase Price Allocation on Fair Value Basis to Identifiable Net Assets (Details) - Assets Purchased from Azaya Therapeutics, Inc. [Member] $ in Thousands	Feb. 15, 2017USD ($)
Business Acquisition [Line Items]
Tangible assets	$ 2,586
Intangible assets	1,686
Total assets	4,272
Accounts payable	1,796
Fair value of the common stock issued	2,311
Transaction costs	165
Total consideration	$ 4,272

Composition of Certain Financ_3

Composition of Certain Financial Statement Captions - Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Current Assets [Abstract]
Prepaid services, current		$ 166	$ 121
Prepaid insurance		564	556
Other receivables		55	103
Total other current assets	$ 736	$ 785	$ 780

Composition of Certain Financ_4

Composition of Certain Financial Statement Captions - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment, net [Abstract]
Office and computer equipment		$ 1,279	$ 1,041
Leasehold improvements		1,682	1,686
Property and equipment – gross		2,961	2,727
Less accumulated depreciation		(662)	(402)
Property and equipment – net	$ 2,384	$ 2,299	$ 2,325

Composition of Certain Financ_5

Composition of Certain Financial Statement Captions - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Composition Of Certain Financial Statement Captions [Abstract]
Depreciation expense	$ 0.3	$ 0.4

Composition of Certain Financ_6

Composition of Certain Financial Statement Captions - Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets [Abstract]
Deposits	$ 39	$ 42
Total other assets	$ 39	$ 42

Composition of Certain Financ_7

Composition of Certain Financial Statement Captions - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Payable and Accrued Expenses [Abstract]
Accrued expenses		$ 824	$ 1,182
Accounts payable		721	1,297
Accrued payroll and bonus		423	750
Accrued legal fees		186	509
Accrued vacation		192	64
Accrued R&D studies		230	285
Other current liabilities		201	119
Accounts payable and accrued expenses, Total	$ 2,729	$ 2,777	$ 4,206

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Thousands	Oct. 29, 2018	Aug. 31, 2018	Feb. 27, 2017	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Apr. 27, 2018
Recorded Unconditional Purchase Obligation [Line Items]
Contractual obligation, due in next twelve months				$ 8,653
Contractual obligation				14,743
Initial term of lease			63 months
Lease commencement date			Jan. 1, 2018
Buy-out of obligations lease			$ 600
Common stock, aggregate amount				$ 0	$ 0	$ 0
Lorem Vascular [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Percentage of common stock to be purchased							5.00%
Common stock, aggregate amount							$ 5,000
Amended complaint dismissal date				Oct. 1, 2018
Bimini Technologies LLC | Demand for Arbitration [Member] | Sale and Exclusive License/Supply Agreement [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Potential milestone payment due upon acheivement of gross profit		$ 1,000
Gross profit from sale of company’s puregraft product line		10,000
Potential milestone payment claimed		$ 1,000
Proceeds from milestone payment	$ 1,000
Pre-clinical Research Study Obligations [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Contractual obligation, due in next twelve months				$ 1,800		1,800
Contractual obligation				3,000		$ 2,500
Operating Lease Obligations [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Rent expense				$ 1,400	$ 1,600

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Debt and Lease Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Contractual Obligation Fiscal Year Maturity Schedule [Line Items]
2019	$ 8,653
2020	6,090
Total	14,743
Payment on Lease Office and Manufacturing Space [Member]
Contractual Obligation Fiscal Year Maturity Schedule [Line Items]
2019	1,282
2020	638
2021	638
2022	192
Total	$ 2,750

Term Loan Obligations (Details)

Term Loan Obligations (Details) - USD ($)

Dec. 31, 2018

Aug. 31, 2018

Jun. 19, 2018

Dec. 29, 2017

Nov. 28, 2017

May 29, 2015

Mar. 31, 2019

Mar. 31, 2018

Dec. 31, 2018

Dec. 31, 2017

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

Date from which warrants are exercisable

May 18, 2018

Minimum liquidity covenant

$ 2,000,000

$ 2,000,000

$ 2,000,000

Net proceeds excess receives from unrestricted cash

4,000,000

Interest expense

515,000

$ 423,000

1,922,000

$ 2,049,000

Non-cash amortization

$ 200,000

$ 100,000

$ 600,000

$ 700,000

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

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. 1, 2019

Jun. 1, 2019

Jun. 1, 2019

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

Nov. 30, 2015

Warrant expiration date

May 29, 2025

May 29, 2025

Minimum liquidity covenant

$ 2,000,000

$ 5,000,000

$ 2,000,000

$ 1,500,000

Extended interest-only period

Jun. 1, 2020

Dec. 31, 2018

Dec. 1, 2018

Aug. 1, 2018

Aug. 1, 2018

Debt instrument, interest-only period

The Fourth Amendment also required 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 and Security 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”).

The Second Amendment extends the interest-only period under the Term Loan to December 1, 2018 if the Company receives unrestricted gross cash proceeds of at least $15 million from the sale and issuance of the Company’s equity securities on or before August 31, 2018.

The amendment also extended the interest-only period under the Loan and Security Agreement through August 1, 2018, as the Company successfully closed on a financing and received unrestricted net cash proceeds in excess of $5 million on or before December 29, 2017.

Net proceeds excess receives from unrestricted cash

$ 5,000,000

Amendment fee

$ 350,000

$ 50,000

$ 250,000

Percentage of proceeds received

75.00%

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.

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

$ 15,000,000

Maximum [Member]

Debt Instrument [Line Items]

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

$ 3,000,000

$ 3,000,000

Term Loan Obligations - Term Lo

Term Loan Obligations - Term Loan Outstanding (Details) - Term Loan [Member] - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2019	Dec. 31, 2018		Dec. 31, 2017		May 29, 2015
Additional details relating term loan that is outstanding [Abstract]
Origination Date		May 29, 2015	May 29, 2015		May 29, 2015
Original Loan Amount			$ 17,700		$ 17,700		$ 17,700
Interest Rate	[1]		8.95%		8.95%
Current Monthly Payment			$ 100	[2]	$ 100	[3]
Original Term			48 months		48 months
Remaining Principal (Face Value)			$ 12,980		$ 12,980
[1]	3 month LIBOR rate with a floor of 1% plus 7.95%
[2]	Monthly payment as of December 2018, which reflects interest only
[3]	Monthly payment as of December 2017, which reflects interest only

Term Loan Obligations - Future

Term Loan Obligations - Future Minimum Debt and Lease Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Future contractual principal and final fee payments on all debt and capital lease obligations [Abstract]
2019	$ 8,653
2020	6,090
Total	$ 14,743

Term Loan Obligations - Face Va

Term Loan Obligations - Face Value to Book Value Reconciliation (Details) $ in Thousands	Dec. 31, 2018USD ($)
Reconciliation of Face Value to Book Value [Abstract]
Total debt and lease obligations, including final payment fee (Face Value)	$ 14,743
Less: Debt discount	(541)
Total obligation	$ 14,202

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Provision or benefit for income taxes	$ 0	$ 0
Income Tax Contingency [Abstract]
Valuation allowance	101,091,000	$ 97,089,000
Increase (decrease) in valuation allowance	$ 4,000,000
Corporate income tax rate	21.00%	34.00%
Net tax expense related to remeasurement of deferred tax assets and liabilities due to enactment-date effect of act	$ 0	$ 0
Net operating loss carryforwards, Expire date	begin to expire in 2019 and 2028
State tax credit carryforwards	$ 4,500,000
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
Provisional amount of remeasured deferred tax assets and liabilities due to change in tax rate fully offset by valuation allowance		45,800,000
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
Maximum [Member]
Income Tax Contingency [Abstract]
Corporate income tax rate		35.00%
Federal [Member]
Income Tax Contingency [Abstract]
Tax loss carryforwards	380,600,000
Federal tax carry forward	$ 5,200,000
Federal tax credit carryforward, Expiration date	begin to expire in 2019
Net operating losses	$ 13,100,000
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	$ 156,800,000

Income Taxes - Components of In

Income Taxes - Components of Income/(Loss) Before Income Tax Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S.	$ (8,346)	$ (12,230)
Foreign	(507)	(843)
Income/(loss) before income tax provision (benefit)	$ (8,853)	$ (13,073)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Total Income Tax Provision (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of the total income tax provision tax rate [Abstract]
Income tax expense (benefit) at federal statutory rate	(21.00%)	(34.00%)
Income tax expense (benefit) at state statutory rate	(8.20%)	(6.70%)
Change in valuation allowance	35.80%	(324.50%)
Change in state rate	(0.10%)	(1.50%)
Permanent interest adjustments	0.70%	0.40%
Stock compensation	1.80%	5.20%
Research credit	(1.40%)	(1.90%)
Foreign rate differential		350.40%
NOLs expiring and adjustments to NOL		12.10%
Mark to market adjustment	(5.30%)
Other, net	(2.30%)	0.50%
Total income tax provision	0.00%	0.00%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets [Abstract]
Allowances and reserves	$ 270	$ 140
Accrued expenses	122	154
Stock based compensation	996	1,065
Net operating loss carryforwards	91,197	87,426
Income tax credit carryforwards	8,671	8,587
Property and equipment, principally due to differences in depreciation	548	514
Other, net	38	45
Deferred tax assets (Total)	101,842	97,931
Valuation allowance	(101,091)	(97,089)
Total deferred tax assets, net of allowance	751	842
Deferred tax liabilities [Abstract]
Intangibles assets	(751)	(842)
Total deferred tax liability	(751)	(842)
Net deferred tax assets (liability)	$ 0	$ 0

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule of reconciliation of unrecognized tax benefits activity [Roll Forward]
Unrecognized Tax Benefits – Beginning	$ 2,157	$ 2,062
Gross increases – tax positions in prior period	1	0
Gross decreases – tax positions in prior period	(3)	0
Gross increase – current-period tax positions	61	95
Unrecognized Tax Benefits – Ending	$ 2,216	$ 2,157

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Discretionary or matching contributions	$ 0	$ 0

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock (Details) - USD ($)	Jul. 25, 2018	Jul. 17, 2018	Nov. 28, 2017	Nov. 02, 2017	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	May 24, 2018	May 23, 2018	Nov. 27, 2017
Preferred Stock [Abstract]
Preferred stock, shares authorized (in shares)					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	$ 0.001
Preferred stock, shares issued (in shares)					30,223		30,223	30,223
Preferred stock, shares outstanding (in shares)					4,540		4,606	2,431
Number of shares callable by warrants (in shares)									2,300,000	23,400,000
Common stock issued (in shares)	6,723		10,000
Common Stock [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)	50		36,000
Warrant exercise price (in dollars per share)	$ 39.93		$ 166.65
Common stock issued (in shares)	6,723		10,000		139,855	201	92,169	24,474
2017 Rights Offering [Member]
Preferred Stock [Abstract]
Charge on Non Transferable Subscription Rights				$ 0
Number of shares callable by warrants (in shares)				10,000
Warrant exercise price (in dollars per share)				$ 3.333
Period exercisable from the date of issuance							30 months
Common stock issued (in shares)			10,000
Gross proceeds from private placement of stock			$ 8,800,000
Redemption price of warrant prior to expiration							$ 0.01
Common stock price per share for warrant redemption							$ 8.33
Number of consecutive trading days for warrant redemption							10 days
2017 Rights Offering [Member] | Outstanding Warrants [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)				18,000,000
Number of warrants exercisable				10
2017 Rights Offering [Member] | Common Stock [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)				1
2018 Rights Offering [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)		1
Warrant exercise price (in dollars per share)		$ 39.93
Period exercisable from the date of issuance					30 months		30 months
Common stock issued (in shares)	6,723
Gross proceeds from private placement of stock	$ 5,700,000
Redemption price of warrant prior to expiration					$ 0.50		$ 0.50
Common stock price per share for warrant redemption					$ 181.50		$ 181.50
Number of consecutive trading days for warrant redemption					20 days		20 days
Warrants liability fair value	$ 3,100,000				$ 1,500,000		$ 900,000
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
2018 Rights Offering [Member] | Common Stock [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)	141,183	141,183
Series A Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares issued (in shares)					13,500		13,500	13,500
Convertible preferred stock					3.60%		3.60%	3.60%
Preferred stock, shares outstanding (in shares)					0		0	0
Series B Convertible Preferred Stock [Member]
Preferred Stock [Abstract]
Preferred stock, shares authorized (in shares)											10,000
Preferred stock, par value (in dollars per share)											$ 0.001
Preferred stock, shares issued (in shares)					10,000		10,000	10,000
Preferred stock, shares outstanding (in shares)					1,112		1,112	2,431
Number of shares callable by warrants (in shares)			360,000
Common stock issued (in shares)			60,000
Series B Convertible Preferred Stock [Member] | 2017 Rights Offering [Member]
Preferred Stock [Abstract]
Number of shares callable by warrants (in shares)				10,000
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 issued (in shares)					6,723		6,723
Preferred stock, shares outstanding (in shares)					3,428		3,494	0
Number of shares callable by warrants (in shares)	7,059,150
Number of share converted into common stock for each share (in shares)	25
Series C Convertible Preferred Stock [Member] | Dividend Paid [Member]
Preferred Stock [Abstract]
Dividends payable							$ 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
Common Stock and Series B Convertible Preferred Stock [Member] | 2018 Rights Offering [Member]
Preferred Stock [Abstract]
Charge on Non Transferable Subscription Rights		$ 0

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock (Details) - USD ($)

Sep. 21, 2018

Jul. 25, 2018

Jun. 01, 2018

Nov. 28, 2017

May 31, 2017

Apr. 11, 2017

Mar. 31, 2019

Dec. 31, 2018

Mar. 31, 2018

Dec. 31, 2018

Mar. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Common Stock [Abstract]

Common stock issued (in shares)

6,723

10,000

Proceeds from sale of common stock, net

$ 1,919,000

$ (150,000)

$ 0

$ 0

Common stock issued, value

$ 1,873,000

$ 27,000

$ 1,624,000

$ 12,716,000

Common Stock [Member]

Common Stock [Abstract]

Common stock issued (in shares)

6,723

10,000

139,855

201

92,169

24,474

Share issued, price per share

$ 550

Common Stock [Member] | Maxim Group LLC [Member]

Common Stock [Abstract]

Common stock issued (in shares)

1,698

17,881

Share issued, price per share

$ 550

$ 520

Proceeds from sale of common stock, net

$ 800,000

$ 8,700,000

Closing of offering date

Apr. 17, 2017

Number of days granted as option to purchase additional shares of common stock to underwriter

45 days

Additional shares of common stock

1,888

Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member]

Common Stock [Abstract]

Common stock issued (in shares)

1,584

200,000

Proceeds from sale of common stock, net

$ 1,700,000

$ 3,800,000

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

200,000

Proceeds from sale of common stock, net

$ 1,700,000

Proceeds from sale of common stock, net

$ 3,800,000

$ 3,800,000

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, value

$ 5,000,000

Period exercisable from the date of issuance

24 months

Common stock issued (in shares)

0

Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Securities Purchase Agreement [Member]

Common Stock [Abstract]

Trading Volume of Common Shares

0

Upper Limit on the Price Per Share

$ 0

Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Maximum [Member]

Common Stock [Abstract]

Beneficial ownership percentage of common stock outstanding

4.99%

Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Maximum [Member] | Single Regular Purchase [Member]

Common Stock [Abstract]

Common stock issued (in shares)

5,000

Common stock issued (in shares)

5,000

Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Minimum [Member] | Single Regular Purchase [Member]

Common Stock [Abstract]

Common stock issued, value

$ 1,000,000

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 stock issued (in shares)

12,802

Common Stock [Member] | Lincoln Park Capital Fund, LLC [Member] | Purchase Agreement [Member] | Maximum [Member]

Common Stock [Abstract]

Floor price of per share

$ 12.50

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($)	May 31, 2018	May 31, 2017	Jan. 31, 2017	May 31, 2016	Dec. 29, 2015	Aug. 31, 2015	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Securities remaining and available for future issuances (in shares)							20,114
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							$ 200,000
Weighted average period for recognition of cost							1 year 6 months
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
Securities remaining and available for future issuances (in shares)							18,957
2015 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares to be issued (in shares)			500		133
Securities remaining and available for future issuances (in shares)							3

Stock-based Compensation - Stoc

Stock-based Compensation - Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Options [Roll Forward]
Balance as of January 1, 2018 (in shares) | shares	2,017
Granted (in shares) | shares	2,346
Expired (in shares) | shares	(20)
Cancelled/forfeited (in shares) | shares	(1,591)
Balance as of December 31, 2018 (in shares) | shares	2,752
Weighted Average Exercise Price [Roll Forward]
Balance as of January 1, 2018 (in dollars per share) | $ / shares	$ 5,962.50
Granted (in dollars per share) | $ / shares	108
Expired (in dollars per share) | $ / shares	38,553.50
Cancelled/forfeited (in dollars per share) | $ / shares	296.50
Balance as of December 31, 2018 (in dollars per share) | $ / shares	$ 4,003.50

Stock-based Compensation - St_2

Stock-based Compensation - Stock Options Vested and Expected to Vest (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Options [Roll Forward]
Balance as of December 31, 2018	2,752	2,017
Vested and expected to vest at December 31, 2018	2,452
Exercisable at December 31, 2018	1,296
Weighted Average Exercise Price [Roll Forward]
Balance as of December 31, 2018 (in dollars per share)	$ 4,003.50
Vested and expected to vest at December 31, 2018	4,447
Exercisable at December 31, 2018	$ 8,099.50
Weighted Average Remaining Contractual Term [Roll Forward]
Balance as of December 31, 2018	7 years 10 months 24 days
Vested and expected to vest at December 31, 2018	7 years 9 months 10 days
Exercisable at December 31, 2018	6 years 7 months 2 days

Stock-based Compensation - Weig

Stock-based Compensation - Weighted-average Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Black-Scholes-Merton option valuation model based on weighted-average assumptions [Abstract]
Expected term	7 years 1 month 6 days	6 years 7 months 6 days
Risk-free interest rate	2.94%	2.20%
Volatility	92.87%	78.84%
Resulting weighted average grant date fair value (in dollars per share)	$ 1.74	$ 1.05

Stock-based Compensation - Comp

Stock-based Compensation - Compensation Cost Recognized for Stock Options and Restricted Stock Awards (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
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)	$ 49	$ 143	$ 355	$ 753

Stock-based Compensation - Co_2

Stock-based Compensation - Compensation Cost Recognized for Stock Options and Restricted Stock Awards (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Total compensation cost for share-based payment arrangement, Net of tax	$ 0	$ 0

SCHEDULE II - VALUATION AND Q_2

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year		$ 0	$ 0
Additions	[1]	0	0
Deductions	[2]	0	0
Other	[3]	0	0
Balance at end of year		$ 0	$ 0
[1]	Includes charges to costs and expenses.
[2]	Deductions for uncollectible accounts receivable includes payments collected and devices recovered from customers.
[3]	Miscellaneous activity.

Basis of Presentation and New_3

Basis of Presentation and New Accounting Standards (Details) $ / shares in Units, $ in Millions	May 23, 2018$ / sharesshares	Mar. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018$ / sharesshares	May 24, 2018shares	Dec. 31, 2017$ / sharesshares
Basis Of Presentation And New Accounting Standards [Line Items]
Reverse stock split of common stock	0.1
Common stock, par value (in dollars per share) | $ / shares	$ 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	438,116	296,609	6,200,000	115,651
Common stock, shares outstanding (in shares)	61,600,000	438,116	296,609	6,200,000	115,651
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
Common stock, reverse stock split, fractional shares issued	0
Operating lease, right-of-use asset | $		$ 2.2
Operating lease, liability | $		$ 2.2
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

Liquidity (Details)

Liquidity (Details) - USD ($)	Apr. 25, 2019	Apr. 24, 2019	Sep. 21, 2018	Aug. 28, 2018	Jul. 25, 2018	Jun. 01, 2018	Nov. 28, 2017	Sep. 05, 2017	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2018	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 24, 2018	May 23, 2018	Dec. 31, 2016
Liquidity [Line Items]
Net loss									$ 3,150,000		$ 4,409,000			$ 12,634,000	$ 22,686,000
Accumulated deficit									(417,533,000)	$ (414,383,000)		$ (414,383,000)	$ (417,533,000)	(414,383,000)	(401,749,000)
Net cash used in operating activities									$ (3,270,000)		(4,119,000)			$ (11,975,000)	(18,128,000)
Substantial doubt about going concern, description									These factors raise substantial doubt about the Company’s ability to continue as a going concern.					These factors raise substantial doubt about the Company’s ability to continue as a going concern
Cash and cash equivalents									$ 3,872,000	5,261,000		5,261,000	3,872,000	$ 5,261,000	9,550,000			$ 12,600,000
Minimum cash/cash equivalents covenant									2,000,000	2,000,000		2,000,000	2,000,000	2,000,000
Proceeds from sale of common stock, net									1,919,000		(150,000)			0	0
Common stock issued (in shares)					6,723		10,000
Number of shares callable by warrants (in shares)																2,300,000	23,400,000
Proceeds from issuance warrants					$ 5,700,000		$ 8,800,000
Common stock issued, value									$ 1,873,000		$ 27,000			$ 1,624,000	$ 12,716,000
Subsequent Event [Member] | Cytori Ltd. and Cell Therapy Assets [Member]
Liquidity [Line Items]
Cash proceeds from sale of subsidiary		$ 3,400,000
Subsequent Event [Member] | Cytori Ltd. and Cell Therapy Assets [Member] | Amendment to Loan and Security Agreement [Member]
Liquidity [Line Items]
Payments for principal, interest and fees		$ 1,700,000
Subsequent Event [Member] | Cytori Therapeutics, K.K. and Cell Therapy Assets used in Japan [Member]
Liquidity [Line Items]
Cash proceeds from sale of subsidiary	$ 2,500,000
Subsequent Event [Member] | Cytori Therapeutics, K.K. and Cell Therapy Assets used in Japan [Member] | Amendment to Loan and Security Agreement [Member]
Liquidity [Line Items]
Payments for principal, interest and fees	$ 1,400,000
Nasdaq Stock Market LLC [Member]
Liquidity [Line Items]
Number of consecutive business days no longer able to meet the required closing bid price of common stock				30 days				30 days
Minimum bid price of common stock required for Nasdaq listing rule				$ 1				$ 1
Grace period provided with minimum bid price for Nasdaq listing rule				180 days				180 days
Grace date for minimum bid price requirement for Nasdaq listing				Feb. 25, 2019				Mar. 5, 2018
Common stock minimum bid price required to regain compliance				$ 1				$ 1
Number of consecutive business days required to regain compliance				10 days				10 days
Date to regain compliance after meeting continued listing requirement				Aug. 26, 2019				Sep. 4, 2018
Additional grace period provided with minimum bid price to regain compliance				180 days				180 days
Description of compliance with minimum bid price requirement				We were 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.										We were 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.
Series C Convertible Preferred Stock [Member]
Liquidity [Line Items]
Number of convertible shares converted into common stock (in shares)					168,478
Number of shares callable by warrants (in shares)					7,059,150
Common stock issued, value														$ 3,041,000
Common Stock [Member]
Liquidity [Line Items]
Common stock issued (in shares)					6,723		10,000		139,855		201			92,169	24,474
Number of shares callable by warrants (in shares)					50		36,000
Warrant exercise price (in dollars per share)					$ 39.93		$ 166.65
Common Stock [Member] | Series C Convertible Preferred Stock [Member]
Liquidity [Line Items]
Number of convertible shares converted into common stock (in shares)									1,652					80,868
Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member]
Liquidity [Line Items]
Proceeds from sale of common stock, net												$ 1,700,000	$ 3,800,000
Common stock issued (in shares)												1,584	200,000
Common Stock [Member] | Lincoln Park [Member]
Liquidity [Line Items]
Proceeds from sale of common stock, net										$ 300,000
Common stock issued (in shares)									0	12,802
Common stock issued, value			$ 5,000,000
Period exercisable from the date of issuance			24 months
Minimum [Member]
Liquidity [Line Items]
Unrestricted cash and cash equivalents									$ 2,000,000	$ 2,000,000		$ 2,000,000	$ 2,000,000	$ 2,000,000
Maximum [Member] | Common Stock [Member] | B. Riley FBR [Member] | Sales Agreement [Member]
Liquidity [Line Items]
Proceeds from sale of common stock, net						$ 6,500,000

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Development revenue recognized	$ 737	$ 917	$ 2,983	$ 3,722
Customer Concentration Risk [Member] | Revenue Recognized [Member]
Concentration Risk [Line Items]
Concentration risk percentage	100.00%	100.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk percentage	100.00%	100.00%

Inventories - Additional Inform

Inventories - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventory, net	$ 107	$ 107	$ 107

Loss per Share (Details)

Loss per Share (Details) - shares	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
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)	300,000	46,858	300,000	9,458
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)	200,000		200,000
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)	2,676
Preferred Stock and Restricted Stock Awards [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)	92,523		94,589

Commitments - Additional Inform

Commitments - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Recorded Unconditional Purchase Obligation [Line Items]
Restricted cash	$ 40
Contractual obligation, due in next twelve months		$ 8,653
Contractual obligation		14,743
Pre-clinical Research Study Obligations [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Contractual obligation, due in next twelve months	1,800	1,800
Contractual obligation	$ 2,500	$ 3,000
Minimum [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating and financing lease, lease term	2 years
Maximum [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Operating and financing lease, lease term	11 years

Commitments - Summary of Lease

Commitments - Summary of Lease Liabilities and Right-of-Use Assets (Details) $ in Thousands	Mar. 31, 2019USD ($)
Assets
Operating	$ 908
Financing	215
Total leased assets	1,123
Liabilities
Operating lease liabilities, current	215
Financing lease liabilities, current	130
Operating lease liabilities. noncurrent	693
Financing lease liabilities, noncurrent	85
Total lease liabilities	$ 1,123

Commitments - Summary of Leas_2

Commitments - Summary of Lease Costs (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Lease expense:
Operating lease expense	$ 55
Finance lease expense:
Depreciation of right-of-use assets	33
Total lease expense	88
Cash payment information:
Operating cash used for operating leases	55
Financing cash used for financing leases	28
Total cash paid for amounts included in the measurement of lease liabilities	$ 83
Weighted-average remaining lease term (years) - operating leases	7 years 3 months 18 days
Weighted-average remaining lease term (years) - finance leases	1 year 9 months 18 days
Weighted-average discount rate - operating leases	8.00%
Weighted-average discount rate - finance leases	5.00%

Commitments - Summary of Future

Commitments - Summary of Future Minimum Annual Lease Payments under Operating and Financing Leases (Details) $ in Thousands	Mar. 31, 2019USD ($)
Financing Leases
Remaining 2019	$ 100
2020	120
2021	7
Total minimum lease payments	227
Less: amount representing interest	(13)
Present value of obligations under leases	214
Less: current portion	(130)
Noncurrent lease obligations	84
Operating Leases
Remaining 2019	527
2020	690
2021	668
2022	281
2023	100
Thereafter	447
Total minimum lease payments	2,713
Less: amount representing interest	(495)
Present value of obligations under leases	2,218
Less: current portion	(700)
Noncurrent lease obligations	$ 1,518

Contingencies (Details)

Contingencies (Details) - Demand for Arbitration [Member] - Bimini Technologies LLC - Sale and Exclusive License/Supply Agreement [Member] - USD ($) $ in Millions	Oct. 29, 2018	Aug. 31, 2018
Recorded Unconditional Purchase Obligation [Line Items]
Potential milestone payment due upon acheivement of gross profit		$ 1
Gross profit from sale of company’s puregraft product line		10
Potential milestone payment claimed		$ 1
Proceeds from milestone payment	$ 1

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Estimated Fair Value Determined Using Option Pricing Model Assumptions (Details)	Mar. 31, 2019$ / shares	Dec. 31, 2018$ / shares	Jul. 25, 2018$ / shares
Measurement Input, Expected Term
Class Of Stock [Line Items]
Warrants expected term	1 year 9 months 18 days	2 years 1 month 6 days	2 years 6 months
Measurement Input, Share Price
Class Of Stock [Line Items]
Warrants measurement input	13	14.50	36
Measurement Input, Risk Free Interest Rate
Class Of Stock [Line Items]
Warrants measurement input	0.0238	0.0248	0.0270
Measurement Input, Price Volatility
Class Of Stock [Line Items]
Warrants measurement input	1.28	1.25	1.12
Measurement Input Resulting Fair Value Per Warrant
Class Of Stock [Line Items]
Warrants measurement input	5	6.50	22.50

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Change in Level 3 Warrant Liability Value (Details) - Warrant Liability [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Warrant liability
Beginning balance	$ 916	$ 3,149
Change in fair value	(210)	(2,233)
Ending balance	$ 706	$ 916

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Apr. 29, 2019	Apr. 25, 2019	Apr. 24, 2019	Mar. 31, 2019
Subsequent Event [Line Items]
Impairment of intangible assets				$ 0
Amendment to Loan and Security Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Amendment fee	$ 600,000
Sale of UK Subsidiary and Certain Assets [Member] | Loan and Security Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Cash proceeds from sale of subsidiary			$ 4,000,000
Payments for principal, interest and fees			$ 1,700,000
Sale of UK Subsidiary and Certain Assets [Member] | Amendment to Loan and Security Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Payments for principal, interest and fees	1,700,000
Sale of the Japanese Subsidiary and Certain Assets [Member] | Loan and Security Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Cash proceeds from sale of subsidiary		$ 3,000,000
Payments for principal, interest and fees		$ 1,400,000
Sale of the Japanese Subsidiary and Certain Assets [Member] | Amendment to Loan and Security Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Payments for principal, interest and fees	$ 1,400,000