Humanigen (HGENQ) S-1/A 9 Jul 20 IPO registration (amended) Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2020
Document and Entity Information
Entity Registrant Name	HUMANIGEN, INC
Entity Central Index Key	0001293310
Document Type	S-1/A
Amendment Flag	true
Amendment Description	The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until this Registration Statement shall become effective on such date as the Commission acting pursuant to said Section 8(a) may determine.
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 68	$ 143	$ 814
Prepaid expenses and other current assets	293	309	485
Total current assets	361	452	1,299
Restricted cash	71	71	71
Total assets	432	523	1,370
Current liabilities:
Accounts payable	5,906	5,046	2,856
Accrued expenses	3,500	3,308	3,129
Advance notes	2,149	2,113	807
Convertible notes - current	2,756	2,033
Notes payable to vendors	1,122	1,094	1,471
Total current liabilities	15,433	13,594	8,263
Convertible notes - non current	1,288	1,247	1,217
Total liabilities	16,721	14,841	9,480
Stockholders' deficit:
Common stock, $0.001 par value: 225,000,000 shares authorized at March 31, 2020, December 31, 2019 and December 31, 2018; 114,311,790, 114,034,451 and 109,897,526 shares issued and outstanding at March 31, 2020, December 31, 2019 and December 31, 2018, respectively	114	114	110
Additional paid-in capital	270,959	270,463	266,381
Accumulated deficit	(287,362)	(284,895)	(274,601)
Total stockholders' deficit	(16,289)	(14,318)	(8,110)
Total liabilities and stockholders' deficit	$ 432	$ 523	$ 1,370

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized	225,000,000	225,000,000	225,000,000
Common stock, shares issued	114,311,790	114,034,451	109,897,526
Common stock, shares outstanding	114,311,790	114,034,451	109,897,526

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 659	$ 359	$ 2,616	$ 2,219
General and administrative	1,398	1,879	6,328	9,112
Total operating expenses	2,057	2,238	8,944	11,331
Loss from operations	(2,057)	(2,238)	(8,944)	(11,331)
Other expense:
Interest expense	(410)	(302)	(1,349)	(852)
Other income (expense), net		(1)	(1)	324
Reorganization items, net				(145)
Net loss	$ (2,467)	$ (2,541)	(10,294)	(12,004)
Other comprehensive income
Comprehensive loss			$ (10,294)	$ (12,004)
Basic and diluted net loss per common share	$ (0.02)	$ (0.02)	$ (0.09)	$ (0.13)
Weighted average common shares outstanding used to calculate basic and diluted net loss per common share	114,270,532	110,033,098	111,806,251	94,756,375

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Deficit - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Total
Balances at Dec. 31, 2017	$ 15	$ 238,246	$ (262,597)	$ (24,336)
Balances (in shares) at Dec. 31, 2017	14,946,712
Conversion of notes payable and related accrued interest and fees to common stock	$ 76	18,356		18,432
Conversion of notes payable and related accrued interest and fees to common stock (in shares)	76,007,754
Issuance of common stock	$ 19	2,762		2,781
Issuance of common stock (in shares)	18,653,320
Issuance of common stock in connection with financing agreement
Issuance of common stock in connection with financing agreement (in shares)	30,000
Beneficial conversion feature of Advance Notes		271		271
Beneficial conversion feature of Convertible Notes		1,465		1,465
Issuance of stock options for payment of accrued compensation		303		303
Issuance of common stock in lieu of cash compensation		85		85
Issuance of common stock in lieu of cash compensation (in shares)	151,407
Issuance of common stock in exchange for services		81		81
Issuance of common stock in exchange for services (in shares)	108,333
Issuance of common stock upon note conversions				18,432
Issuance of warrant for services
Stock-based compensation expense		4,812		4,812
Comprehensive loss			(12,004)	(12,004)
Balances at Dec. 31, 2018	$ 110	266,381	(274,601)	(8,110)
Balances (in shares) at Dec. 31, 2018	109,897,526
Issuance of stock options for payment of accrued compensation				195
Issuance of common stock in exchange for services	$ 82,432	68		68
Issuance of stock options for payment of compensation		195		195
Issuance of stock options for payment of compensation, shares
Exercise of common stock options/Issuance of common stock for payment of compensation		90		90
Exercise of common stock options/Issuance of common stock for payment of compensation (in shares)	93,358
Exercise of stock options		50		50
Exercise of stock options, shares	75,000
Issuance of warrant for services
Stock-based compensation expense		697		697
Comprehensive loss			(2,541)
Balances at Mar. 31, 2019	$ 110	267,481	(277,142)	(9,551)
Balances (in shares) at Mar. 31, 2019	110,148,316
Balances at Dec. 31, 2018	$ 110	266,381	(274,601)	(8,110)
Balances (in shares) at Dec. 31, 2018	109,897,526
Issuance of common stock	$ 1	185		186
Issuance of common stock (in shares)	500,000
Issuance of common stock in connection with financing agreement	$ 1	(1)
Issuance of common stock in connection with financing agreement (in shares)	706,592
Beneficial conversion feature of Advance Notes
Beneficial conversion feature of Convertible Notes				143
Issuance of stock options for payment of accrued compensation		207		207
Issuance of common stock for payment of accrued compensation		137		137
Issuance of common stock for payment of accrued compensation (in shares)	152,223
Issuance of common stock in exchange for services		83		83
Issuance of common stock in exchange for services (in shares)	109,863
Issuance of common stock upon note conversions	$ 2	979		981
Issuance of common stock upon note conversions (in shares)	2,179,622
Convertible note beneficial conversion feature		143		143
Exercise of common stock options/Issuance of common stock for payment of compensation		324		$ 324
Exercise of common stock options/Issuance of common stock for payment of compensation (in shares)	488,625
Exercise of stock options, shares				488,625
Issuance of warrant for services
Stock-based compensation expense		2,025		2,025
Comprehensive loss			(10,294)	(10,294)
Balances at Dec. 31, 2019	$ 114	270,463	(284,895)	(14,318)
Balances (in shares) at Dec. 31, 2019	114,034,451
Issuance of common stock		65		65
Issuance of common stock (in shares)	200,000
Issuance of stock options for payment of accrued compensation				133
Issuance of common stock in lieu of cash compensation				19
Issuance of common stock in exchange for services		13		13
Issuance of common stock in exchange for services (in shares)	29,342
Issuance of stock options for payment of compensation		133		133
Exercise of common stock options/Issuance of common stock for payment of compensation		19		$ 19
Exercise of common stock options/Issuance of common stock for payment of compensation (in shares)	47,997
Exercise of stock options, shares
Issuance of warrant for services		1		$ 1
Stock-based compensation expense		265		265
Comprehensive loss			(2,467)
Balances at Mar. 31, 2020	$ 114	$ 270,959	$ (287,362)	$ (16,289)
Balances (in shares) at Mar. 31, 2020	114,311,790

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (2,467)	$ (2,541)	$ (10,294)	$ (12,004)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization				19
Noncash interest expense			1,295	819
Stock based compensation expense	265	697	2,025	4,812
Issuance of common stock for payment of accrued compensation	19	48	137	85
Gain on disposal of assets				(276)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	16	5	176	328
Accounts payable	860	592	2,190	(198)
Accrued expenses	687	447	387	125
Net cash used in operating activities	(607)	(684)	(4,001)	(6,209)
Financing activities:
Net proceeds from issuance of common stock	65		185	2,781
Net proceeds from term loan		50		50
Proceeds from exercise of stock options			325
Net proceeds from issuance of Convertible notes	467		1,275	2,500
Net proceeds from issuance of Advance notes			2,050	925
Payments on notes payable to vendors			(505)
Net cash provided by financing activities	532	50	3,330	6,256
Net increase (decrease) in cash, cash equivalents and restricted cash	(75)	(634)	(671)	47
Cash, cash equivalents and restricted cash, beginning of period	214	885	885	838
Cash, cash equivalents and restricted cash, end of period	139	251	214	885
Supplemental cash flow disclosure:
Cash paid for interest	2	1	13	8
Supplemental disclosure of non-cash investing and financing activities:
Conversion of notes payable and related accrued interest and fees to common stock			981	18,432
Beneficial conversion feature of Advance notes				271
Beneficial conversion feature of Convertible notes			143	1,465
Issuance of stock options in lieu of cash compensation	133	195	207	303
Issuance of common stock for payment of accrued compensation			137	85
Issuance of common stock in exchange for services			83	81
Issuance of warrant for services	$ 1

Nature of Operations

Nature of Operations	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Description of the Business The Company was incorporated on March 15, 2000 in California and reincorporated as a Delaware corporation in September 2001 under the name KaloBios Pharmaceuticals, Inc. Effective August 7, 2017, the Company changed its legal name to Humanigen, Inc. During February 2018, the Company completed the restructuring transactions announced in December 2017 and continued its transformation into a clinical-stage biopharmaceutical company by further The Company’s lead product candidate is lenzilumab, a proprietary Humaneered® monoclonal antibody (a biologic) that has been demonstrated to neutralize a naturally occurring inflammatory factor (GM-CSF). GM-CSF is a cytokine which acts directly on myeloid cells to cause expansion, activation, and to initiate and promote the production of other chemokines, including MCP-1, MIP-1a, and IP-10, and cytokines, including TNFa, IL-6 and IL-1 as part of the body’s immune response. GM-CSF is thought of as a communication conduit between the innate and adaptive immune systems. Once initiated, the inflammatory cascade in certain cases may quickly evolve into a self-perpetuating “storm” as the production of chemokines increases expansion and trafficking of myeloid cells. This, in turn, leads to abnormally high levels of inflammatory cytokines, endothelial activation, vascular permeability, disseminated intravascular coagulation, and neurologic inflammation. This “cytokine storm” is frequently referred to as cytokine release syndrome, or CRS. The neutralization of GM-CSF has been shown to prevent and potentially treat cytokine storm through a decrease in levels of IL-6, MCP-1, MIP1a, IP-10, VEGF, TNFα and other factors and reduce levels of inflammatory myeloid cells. Reduction of these factors demonstrates that GM-CSF is a critical upstream and early regulator of many inflammatory cytokines known to be important in the pathophysiology of CRS (Sterner RM et al. Blood 2019. 133(7): 697–709). During 2019 and throughout the early portion of the first quarter of 2020, the Company continued to pursue its anti-GM-CSF programs to prevent or reduce the serious and potentially life-threatening side effects associated with chimeric antigen receptor T-cell (“CAR-T”) therapy and to prevent or treat graft-versus-host disease (“GvHD”) in patients undergoing allogeneic hematopoietic stem cell transplantation (“HSCT”). In collaboration with Kite Pharmaceuticals, Inc., a Gilead company (“Kite or the “Kite Collaboration”), the Company seeks to study the effect of lenzilumab on the safety of Yescarta®, axicabtagene ciloleucel (“Yescarta”), Kite’s FDA-approved CAR-T therapy. A clinical trial is underway to measure the effect of lenzilumab in reducing CRS and neurotoxicity (NT), with a secondary endpoint of increased efficacy of Yescarta. The recent coronavirus pandemic, which is due to the SARS-CoV-2 virus and leads to the condition referred to as COVID-19, is frequently characterized in the later and sometimes fatal stages by severe, progressive viral pneumonia that can progress to acute respiratory distress syndrome (“ARDS”), respiratory failure and death. Recent publications indicate that ARDS in this setting is caused by the body’s autoimmune response to CRS. Published data point to GM-CSF being a key triggering cytokine, with elevated levels especially in those patients who transition to the Intensive Care Unit (“ICU”). In response to this published data indicating that GM-CSF inhibition may play a role in treating patients with COVID-19, the Company is developing lenzilumab in COVID-19 in a Phase III potential registration study. The Company has commenced enrollment in a multicenter randomized, placebo-controlled, double-blind clinical trial with lenzilumab for the prevention of respiratory failure and/or death in hospitalized patients with severe pneumonia associated with SARS-CoV-2 infection (Clinicaltrials.gov # NCT04351152). The Company has generated compassionate use data with lenzilumab in patients hospitalized with severe pneumonia associated with COVID-19 and is working with stakeholders to share these data. See Management’s Discussion and Analysis of Financial Condition and Results of Operations in Item 2 of this Quarterly Report on Form 10-Q for additional information regarding the business. Liquidity and Going Concern The Company has incurred significant losses since its inception in March 2000 and had an accumulated deficit of $287.4 million as of March 31, 2020. At March 31, 2020, the Company had a working capital deficit of $15.1 million. To date, none of the Company’s product candidates has been approved for sale and therefore the Company has not generated any revenue from product sales. Management expects operating losses to continue for the foreseeable future. The Company will require additional financing in order to meet its anticipated cash flow needs, which are expected to increase as the Company’s clinical trial activities accelerate during the next twelve months. As a result, the Company will continue to require additional capital through equity offerings, debt financing and/or payments under new or existing licensing or collaboration agreements. If sufficient funds are not available on acceptable terms when needed, the Company could be required to significantly reduce its operating expenses and delay, reduce the scope of, or eliminate one or more of its development programs. The Company’s ability to access capital when needed is not assured and, if not achieved on a timely basis, could materially harm its business, financial condition and results of operations. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. The Condensed Consolidated Financial Statements for the three months ended March 31, 2020 were prepared on the basis of a going concern, which contemplates that the Company will be able to realize assets and discharge liabilities in the normal course of business. The ability of the Company to meet its total liabilities of $16.7 million at March 31, 2020 and to continue as a going concern is dependent upon the availability of future funding. The financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern. Basis of Presentation The accompanying interim unaudited Condensed Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and on a basis consistent with the annual consolidated financial statements and include all adjustments necessary for the presentation of the Company’s condensed consolidated financial position, results of operations and cash flows for the periods presented. The Condensed Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries. These financial statements have been prepared on a basis that assumes that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. The December 31, 2019 Condensed Consolidated Balance Sheet was derived from the audited financial statements but does not include all disclosures required by U.S. GAAP. These interim financial results are not necessarily indicative of the results to be expected for the year ending December 31, 2020, or for any other future annual or interim period. The accompanying unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited consolidated financial statements and the related notes thereto included in the Company’s 2019 Form 10-K. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the Condensed Consolidated Financial Statements and accompanying notes. Actual results could differ materially from those estimates. The Company believes judgment is involved in determining the valuation of the fair value-based measurement of stock-based compensation and warrant valuations. The Company evaluates its estimates and assumptions as facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ from these estimates and assumptions, and those differences could be material to the Condensed Consolidated Financial Statements. Certain prior year amounts have been reclassified to conform to the current year presentation. Such reclassifications had no effect on prior years’ Net loss or Stockholders’ deficit.

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business Description of the Business Humanigen, Inc. (the “Company”) was incorporated on March 15, 2000 in California and reincorporated as a Delaware corporation in September 2001 under the name KaloBios Pharmaceuticals, Inc. Effective August 7, 2017, the Company changed its legal name to Humanigen, Inc. During February 2018, the Company completed the restructuring transactions announced in December 2017 and furthered its transformation into a clinical-stage biopharmaceutical company. During 2019, the Company completed its transformation into a clinical stage biopharmaceutical company, Yescarta®” Kymriah® (“Kymriah” or “Kymriah®”) The Company is also exploring the effectiveness of its GM-CSF neutralization technologies (either through the use of lenzilumab as a neutralizing antibody or through GM-CSF gene knockout) in combination with other CAR-T, T-cell engaging, and immunotherapy treatments to break the efficacy/toxicity linkage, including the prevention and/or treatment of graft-versus-host disease (“GvHD”) while preserving graft-versus-leukemia (“GvL”) benefits in patients undergoing allogeneic HSCT. In this context, GvHD is akin to CRS, or cytokine storm and the Company believe the mechanism to be driven by GM-CSF levels. The recent coronavirus pandemic which is due to the SARS-CoV-2 virus and leads to the condition referred to as COVID-19, is characterized in the later and sometimes fatal stages by lung dysfunction which is triggered by CRS, or cytokine storm. Recent publications point to GM-CSF being a key cytokine, with elevated levels especially in those patients who transition to the Intensive Care Unit (ICU).The Company has established several partnerships with leading institutions to advance its innovative pipeline and is in active discussion with several government and commercial organizations. The Company believes that it has a dominant intellectual property position in the area of GM-CSF neutralization through multiple approaches and mechanisms, as they pertain to CAR-T, GvHD and multiple other oncology/transplantation, inflammation, fibrosis and autoimmune conditions which may be driven by GM-CSF. The Company has also advanced its preclinical next-generation cell and gene therapies for the treatment of cancers via its novel human granulocyte-macrophage colony-stimulating factor (“GM-CSF”) neutralization and gene-knockout platforms. As a leader in GM-CSF pathway science, the Company believes that it has the ability to transform prevention of CRS in SARS-CoV-2 infection. The virus associated with the current COVID-19 pandemic, SARS-Cov-2, is one of a group of several betacoronaviruses, which includes the viruses responsible for Severe Acute Respiratory Syndrome (SARS-CoV) and Middle East Respiratory Syndrome (MERS-CoV). These viruses infect predominantly the lower lung and cause fatal pneumonia. Other coronaviruses infect the upper respiratory tract and cause some cases of the common cold. The clinical course of COVID-19 can be mistaken for influenza infection – patients in both cases often suffer from aches and pains throughout the body, fever, cough and general malaise. COVID-19 is not typically associated with a productive cough – rather it tends to be a dry cough – and sneezing is less common. A nasal or throat swab can be used to test for SARS-CoV-2 infection, and blood tests can be run to check for viral titers. Travel to areas where COVID-19 appears to have a large number of cases and exposure to people who are known to have suffered from the condition or carriers of SARS-CoV-2 also increases the clinical suspicion of possible infection. Data generated during the SARS and MERS outbreaks point to cytokine storm as a phase of the illness which is characterized by an immune hyperactive phase, which then can progress to lung dysfunction and death. The natural history of SARS infection shows viral load actually decreases as patients enter the second phase. Recent data from China and the subject of a pre-publication titled “Aberrant pathogenic GM-CSF+ T cells and inflammatory CD14+CD16+ monocytes in severe pulmonary syndrome patients of a new coronavirus”, supports the hypothesis that cytokine storm-induced immune mechanisms have contributed to patient mortality with the current pandemic strain of coronavirus. The severe clinical features associated with some COVID-19 infections result from an inflammation-induced lung injury requiring Intensive Care Unit (ICU) care and mechanical ventilation. This lung injury is a result of a cytokine storm resulting from a hyper-reactive immune response. The lung injury that leads to death is not directly related to the virus, but appears to be a result of a hyper-reactive immune response to the virus triggering a cytokine storm that can continue even after viral titers begin to fall. The authors of the study assessed samples from patients with severe pneumonia resulting from COVID-19 infection to identify whether inflammatory factors such as GM-CSF, G-CSF, IL-6, MCP-1, MIP 1 alpha, IFN-gamma and TNF-alpha were implicated. The authors noted that steroid treatment in such cases has been disappointing in terms of outcome, but suggested that a monoclonal antibody that targets GM-CSF may prevent or curb the hyper-active immune response caused by COVID-19 in this setting. The Company believes that the authors’ findings are worthy of further investigation, suggesting that to reduce or eradicate ICU care and prevent deaths from COVID-19 infection, an intervention may be needed to prevent cytokine storm. Separate publications confirm that cytokine storm is characterized by surge of high levels of circulating inflammatory cytokines, and is an overreaction of the immune system under the conditions, such as CAR-T therapy and patients infected with SARS-CoV-2. These recent studies revealed that high levels of GM-CSF, along with a few other cytokines, are critically associated with severe clinical complications in COVID-19 patients. High concentration of GM-CSF was found in the plasma of severe and critically ill patients, which account for approximately 20% of all patients, especially in those requiring intensive care. Lenzilumab has been shown to prevent cytokine storm in animal models and this work has been published in peer reviewed journals. Patients are expected to be enrolled soon in a clinical study to determine lenzilumab’s effect on cytokine storm associated with the hyper-active immune response associated with CAR-T therapy in collaboration with Kite Pharma. The Company believes these new data suggest that GM-CSF may be a critical triggering cytokine in the increased mortality in the current coronavirus pandemic. A potential program in COVID-19 to prevent cytokine storm is complementary to the programs in CAR-T and GvHD, which are also focused on preventing or reducing cytokine storm in those disease states. As a leader in GM-CSF pathway science, the Company believes that it has the ability to transform chimeric antigen receptor T-cell (“CAR-T”) therapy and a broad range of other T-cell engaging therapies, including both autologous and allogeneic cell transplantation. There is a direct correlation between the efficacy of CAR-T therapy and the incidence of life-threatening toxicities (referred to as the efficacy/toxicity linkage). The Company believes that its GM-CSF neutralization and gene-editing CAR-T platform technologies have the potential to reduce the inflammatory cascade associated with serious and potentially life-threatening CAR-T therapy-related side-effects while preserving and potentially improving the efficacy of the CAR-T therapy itself, thereby breaking the efficacy/toxicity linkage. Clinical correlative analysis and preclinical in-vivo The Company believes that its GM-CSF pathway science, assets and expertise create two technology platforms to assist in the development of next-generation CAR-T therapies. Lenzilumab, the Company’s proprietary Humaneered anti-GM-CSF immunotherapy, has the potential to be used in combination with any U.S. FDA-approved or development stage T-cell therapies, including CAR-T therapy, as well as in combination with other cell therapies such as hematopoietic stem cell therapy (“HSCT”), to make these treatments safer and more effective. The Company has utilized a precision medicine approach and personalized the development of lenzilumab based on specific genetic mutations or biomarkers at baseline. The Company recently reported on a Phase I study of lenzilumab as monotherapy in refractory chronic myelomonocytic leukemia (CMML) and is now planning a potential Phase II study of lenzilumab in combination with azacitidine (current standard therapy) in newly diagnosed CMML patients with certain genetic mutations. The Company is also planning a potential Phase II/III study focused on early intervention with lenzilumab in patients at high risk for acute Graft versus Host Disease (GvHD) based on specific biomarkers. The Company has also reported on a Phase II study in severe asthma utilizing lenzilumab. In addition, the Company’s GM-CSF knockout gene-editing CAR-T platform has the potential to create next-generation CAR-T therapies that may inherently avoid any efficacy/toxicity linkage, thereby potentially preserving the benefits of the CAR-T therapy while reducing or altogether avoiding its serious and potentially life-threatening side-effects. The Company’s immediate focus is combining FDA-approved and development stage CAR-T therapies with lenzilumab, its lead product candidate. A clinical collaboration with Kite was recently announced to evaluate the use of lenzilumab with Yescarta in a multicenter clinical trial (ZUMA-19) in adults with relapsed or refractory large B-cell lymphoma. The Company is also creating next-generation combinatory gene-edited CAR-T therapies using strategies to improve efficacy while employing GM-CSF gene knockout technologies to control toxicity. This includes developing its own portfolio of proprietary first-in-class EphA3-CAR-Ts for various solid cancers and EMR1-CAR-Ts for various eosinophilic disorders. Lenzilumab Lenzilumab neutralizes human GM-CSF and has the potential to prevent or reduce certain serious side-effects associated with CAR-T therapy (CRS and neurotoxicity) and improve upon the efficacy of CAR-T therapy. ® There are currently no products approved by the FDA for the prevention of CRS/cytokine storm associated with COVID-19. Also there are currently no products approved by the FDA for the prevention of CAR-T therapy-related side effects, nor are there any approved therapies for the treatment of CAR-T therapty related NT. The Company is continuing to advance the development of lenzilumab in combination with CAR-T therapy through a non-exclusive clinical collaboration with Kite, pursuant to which we are conducting a multi-center Phase Ib/II study (the “Study”) of lenzilumab with Kite’s Yescarta in patients with relapsed or refractory B-cell lymphoma, including diffuse large B-cell lymphoma (“DLBCL”). The Study has been designated the nomenclature ‘ZUMA-19’, consistent with the other Kite CAR-T studies, which also receive a ‘ZUMA’ designation. The primary objective of ZUMA-19 is to determine the effect of lenzilumab on the safety and efficacy of Yescarta. Kite’s Yescarta is one of two CAR-T therapies that have been approved by the FDA and is the CAR-T therapy market leader, and our collaboration with Kite is currently the only clinical collaboration which is now enrolling patients with the potential to improve both the safety and efficacy of CAR-T therapy. The Company also plans to measure other potentially beneficial effects on efficacy and healthcare resource utilization. In addition, lenzilumab’s success in preventing serious and potentially life-threatening side-effects could offer economic benefits to medical system payers by making the CAR-T therapy capable of being administered, and follow-up care subsequently monitored and managed, potentially on an out-patient basis in certain patients and circumstances. In turn, the Company believes that delivering such provider and payer benefits might accelerate the use of the CAR-T therapy itself, and thereby permit us to generate further revenues from sales of lenzilumab. In addition to COVID-19 and CAR-T therapy, the Company is committed to advancing its diverse platform for GM-CSF axis suppression for a broad range of other T-cell engaging therapies, including both autologous and allogeneic next generation CAR-T therapies, bi-specific antibody therapies, as well as other cell-based immunotherapies in development, including allogeneic HSCT, with our current and future partners. In July 2019, the Company entered into the “Zurich Agreement” with the University of Zurich, Switzerland (“UZH”). Under the Zurich Agreement, the Company has in-licensed certain technologies that it believes may be used to prevent or treat GvHD, thereby expanding its development platform to include improving the safety and effectiveness of allogeneic HSCT, a potentially curative therapy for patients with hematological cancers. There are currently no FDA-approved agents for the prevention of GvHD nor treatment of GvHD in patients identified as high risk by certain biomarkers. the Company believes that GM-CSF neutralization with lenzilumab has the potential to prevent or treat GvHD without compromising, and potentially improving, the beneficial graft-versus-leukemia (“GvL”) effect in patients undergoing allogeneic HSCT, thereby making allogeneic HSCT safer. Several recent papers have been published which support this approach, including in Science Translational Medicine in November 2018 and in ‘blood advances’ in October 2019. The Company aims to position lenzilumab as a necessary companion product to any allogeneic HSCT and as a part of the standard pre-conditioning that all patients receiving allogeneic HSCT should receive or as an early treatment option in patients identified as high risk for GvHD. Given its interest in developing lenzilumab to prevent CRS/cytokine storm in COVID-19 as well as in the treatment of rare cancers and other orphan conditions such as GvHD, the Company believes that it has the opportunity to benefit from various regulatory incentives, such as orphan drug exclusivity, breakthrough therapy designation, fast track designation, priority review and accelerated approval. GM-CSF Gene Knockout The Company is advancing its GM-CSF knockout gene-editing CAR-T platform through the Mayo Agreement that it entered into in June 2019 with the Mayo Foundation. Under the Mayo Agreement, the Company has in-licensed certain technologies that it believes may be used to create CAR-T cells lacking GM-CSF Preclinical data indicates that GM-CSF gene knockout CAR-T cells show improved overall survival in animals compared to wild-type CAR-T cells in addition to the expected benefits of reduced serious side-effects associated with CAR-T therapy. The Company is establishing a platform of next-generation combinatorial gene knockout CAR-T cells that have potential to be applied across both autologous and allogeneic approaches and is also investigating multiple CAR-T cell designs using precise dual and triple gene editing to significantly enhance the anti-tumor activity while simultaneously preventing CAR-T therapy induced toxicities. Through targeted gene expression and modulating cytokine activation signaling, the Company may be able to increase the proportion of fitter T-cells produced during expansion, increase their proliferative potential, and inhibit activation-induced cell death, thereby improving the cancer killing activity of our engineered CAR-T cells thereby making them more effective and safer in the treatment of cancers. Initial data were published in an abstract that was presented at the December 2019 American Society of Hematology (ASH) meeting and also won an ASH Abstract Achievement award. The Company plans to continue development of this technology in combination approaches that could add to the observed efficacy benefits of current generation CAR-T products. In addition, the Company anticipates that its GM-CSF knockout gene-editing CAR-T platform may be a future backbone for controlling the serious side-effects that hamper CAR-T therapy that lead to serious and sometimes fatal outcomes for patients as a result of the CAR-T therapy itself. EphA3-CAR: Targeting Tumor Stroma and Tumor Vasculature The Company has begun to generate its own pipeline of CAR-T therapies including an EphA3-CAR-T based on the ifabotuzumab v-region and backbone. Ifabotuzumab is a Humaneered anti-EphA3 monoclonal antibody. Ifabotuzumab has the potential to kill tumor cells by targeting tumor stroma that protects them and the vasculature that feeds them. This unique combination of activities as a backbone of a CAR-T therapy may provide the potential to generate durable responses in a range of solid tumors by targeting the tissues that surround, protect, and nourish a growing cancer. By developing an EphA3-CAR-T using ifabotuzumab as the backbone, the Company may have the ability to target the tumor, tumor stroma, and tumor vasculature in a novel manner. The Company is collaborating with the Mayo Clinic and plans to move to clinical testing with an anti-EphA3 construct for a range of cancer types after completing IND-enabling work. The Company has published initial data from its Phase I study in an abstract that was accepted for the November 2019 Society of Neuro-Oncology (SNO) meeting, showing data in glioblastoma multiforme, a form of brain cancer. EMR1-CAR: Targeting Eosinophils The Company’s EMR1-CAR-T product is based on the HGEN005 (anti-EMR1 Humaneered monoclonal antibody) backbone and targets EMR1. Our EMR1-CAR-T based on the HGEN005 backbone is another approach in our growing platform of CAR-T therapies. The Company believes that because of its high selectivity, EMR1-CAR-T has significant potential to treat serious eosinophil diseases. In preclinical work, HGEN005’s anti-EMR1 activity resulted in dramatically enhanced killing of eosinophils from normal and eosinophilic donors and also induced a rapid and sustained depletion of eosinophils in a non-human primate model without any clinically significant adverse events. The Company has engaged with NIH to discuss expanding the initial work they have conducted utilizing HGEN005 and discussions are underway with a leading center in the U.S. to perform the IND-enabling testing in eosinophilic leukemia, an orphan condition with significant unmet need, as well as with several other potential partners, although there is no assurance that it will reach any agreements for these next steps. Liquidity and Going Concern The Company has incurred significant losses since its inception in March 2000 and had an accumulated deficit of $284.9 million as of December 31, 2019. At December 31, 2019, the Company had a working capital deficit of $13.1 million. During March, April and May of 2019, the Company received aggregate proceeds of $324,000 from the exercise of stock options by our Chairman and Chief Executive Officer and two other members of our Board of Directors. Commencing on April 23, 2019, the Company delivered a series of convertible promissory notes (the “2019 Convertible Notes”) evidencing an aggregate of $1.3 million of loans made to the Company by eleven different lenders. See Note 6 for further description of the 2019 Convertible Notes. On June 28, 2019, the Company received aggregate proceeds of $1.7 million from bridge loans made to the Company (the “June Bridge Notes”) by three different lenders including Dr. Cameron Durrant, the Company’s Chairman and Chief Executive Officer; Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder; and Nomis Bay LTD, our second largest shareholder. See Note 6 for further description of the June Bridge Notes. On November 12, 2019, the Company received aggregate proceeds of $350,000 from bridge loans made to the Company (the “November Bridge Notes”) by two parties, including Dr. Cameron Durrant, the Company’s Chairman and Chief Executive Officer and Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder. See Note 6 for further description of the November Bridge Notes. During the month of December 2019, the Company received aggregate proceeds of approximately $186,000 from the issuance of common stock to Lincoln Park Capital under the Purchase Agreement. See Note 9 for further description of the Purchase Agreement. To date, none of the Company’s product candidates has been approved for sale and therefore the Company has not generated any revenue from product sales. Management expects operating losses to continue for the foreseeable future. The Company will require additional financing in order to meet its anticipated cash flow needs during the next twelve months. As a result, the Company will continue to require additional capital through equity offerings, debt financing and/or payments under new or existing licensing or collaboration agreements. If sufficient funds are not available on acceptable terms when needed, the Company could be required to significantly reduce its operating expenses and delay, reduce the scope of, or eliminate one or more of its development programs. The Company’s ability to access capital when needed is not assured and, if not achieved on a timely basis, could materially harm its business, financial condition and results of operations. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. The Consolidated Financial Statements for the twelve months ended December 31, 2019 were prepared on the basis of a going concern, which contemplates that the Company will be able to realize assets and discharge liabilities in the normal course of business. The ability of the Company to meet its total liabilities of $14.8 million at December 31, 2019 and to continue as a going concern is dependent upon the availability of future funding. The financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern.

Chapter 11 Filing

Chapter 11 Filing	12 Months Ended
	Dec. 31, 2019
Financial Statement Presentation While in Chapter 11 [Abstract]
Chapter 11 Filing	2. Chapter 11 Filing On December 29, 2015, the Company filed a voluntary petition for bankruptcy protection under Chapter 11 of the U.S. Bankruptcy Code. The filing was made in the U.S. Bankruptcy Court for the District of Delaware (the “Bankruptcy Court”) (Case No. 15-12628 (LSS) (the “Bankruptcy Case”). Plan of Reorganization On May 9, 2016, the Company filed with the Bankruptcy Court a Plan of Reorganization and related amended disclosure statement (the “Plan”) pursuant to Chapter 11 of the Bankruptcy Code. On June 16, 2016, the Bankruptcy Court entered an order confirming the Plan. The Plan became effective on June 30, 2016 (the “Effective Date”) and the Company emerged from its Chapter 11 bankruptcy proceedings. Bankruptcy Claims Administration The reconciliation of certain proofs of claim filed against the Company in the Bankruptcy Case, including certain General Unsecured Claims, Convenience Class Claims and Other Subordinated Claims, is complete. As a result of its examination of the claims, the Company asked the Bankruptcy Court to disallow, reduce, reclassify, subordinate or otherwise adjudicate certain claims the Company believes are subject to objection or otherwise improper. On July 11, 2018, the Company filed an objection to the remaining claims. By objection, the Company sought to disallow in their entirety the remaining claims totaling approximately $0.5 million. On September 17, 2018 the Bankruptcy Court issued a Final Decree and Order to close the Bankruptcy Case and terminate the remaining claims and noticing services. Financial Reporting in Reorganization The Company applied Financial Accounting Standards Board (FASB) Accounting Standards Codification (“ASC”) 852, Reorganizations For the years ended December 31, 2019 and 2018, Reorganization items, net consisted of the following charges: Year Ended December 31, 2019 2018 Legal fees $ - $ 119 Professional fees - 26 Total reorganization items, net $ - $ 145 Cash payments for reorganization items totaled $0.2 million for the year ended December 31, 2018. There were no payments for reorganization items for the year ended December 31, 2019.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies There have been no material changes in the Company’s significant accounting policies since those previously disclosed in the 2019 Form 10-K. Derivative Financial Instruments The Company has equity conversion features within its 2020 Convertible Redeemable Notes that qualify as embedded derivatives under the guidance of FASB ASC Topic 815, Derivatives and Hedging	3. Summary of Significant Accounting Policies Basis of Presentation and Use of Estimates The accompanying Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include all adjustments necessary for the presentation of the Company’s consolidated financial position, results of operations and cash flows for the periods presented. The Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries. These financial statements have been prepared on a basis that assumes that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the Consolidated Financial Statements and accompanying notes. Actual results could differ materially from those estimates. The Company believes judgment is involved in accounting for the fair value-based measurement of stock-based compensation, accruals, convertible notes and warrants. The Company evaluates its estimates and assumptions as facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ from these estimates and assumptions, and those differences could be material to the Consolidated Financial Statements. Concentration of Credit Risk Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk in the event of a default by the related financial institution holding the securities, to the extent of the value recorded in the balance sheet. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments with lower credit risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk. Fair Value of Financial Instruments The fair value of financial instruments reflects the amounts that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The fair value hierarchy is based on three levels of inputs that may be used to measure fair value, of which the first two are considered observable, and the third is considered unobservable, as follows: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than those included in Level 1 that are directly or indirectly observable, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company measures the fair value of financial assets and liabilities using the highest level of inputs that are reasonably available as of the measurement date. The following tables summarize the fair value of financial assets (marketable securities) that are measured at fair value, and the classification by level of input within the fair value hierarchy: Fair Value Measurements as of December 31, 2019 Level 1 Level 2 Level 3 Total Investments: Money market funds $ 71 $ — $ — $ 71 Total assets measured at fair value $ 71 $ — — $ 71 Fair Value Measurements as of December 31, 2018 Level 1 Level 2 Level 3 Total Investments: Money market funds $ 71 $ — $ — $ 71 Total assets measured at fair value $ 71 $ — — $ 71 The estimated fair value of the Advance notes, Notes payable to vendors, Bridge notes and Convertible notes as of December 31, 2019 and 2018, based upon current market rates for similar borrowings, as measured using Level 3 inputs, approximate the carrying amounts as presented in the Consolidated Balance Sheets. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of deposits with commercial banks in checking, interest-bearing and demand money market accounts. Restricted Cash Restricted cash at December 31, 2019 of $0.07 million related to a standby letters of credit in the amount of $0.05 million issued in connection with certain insurance policy coverage maintained by the Company and restricted cash related to a credit card facility in the amount of $0.02 million. Restricted cash at December 31, 2018 of $0.07 million related to a standby letters of credit in the amount of $0.05 million issued in connection with certain insurance policy coverage maintained by the Company and restricted cash related to a credit card facility in the amount of $0.02 million. Debt Issue Costs Debt issuance costs related to a recognized debt liability are presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts and are amortized to interest expense over the term of the related debt on the effective interest method. Research and Development Expenses Development costs incurred in the research and development of new product candidates are expensed as incurred, including expenses that may or may not be reimbursed under research and development collaboration arrangements. Research and development costs include, but are not limited to, salaries, benefits, stock-based compensation, laboratory supplies, allocated overhead, fees for professional service providers and costs associated with product development efforts, including preclinical studies and clinical trials. The Company estimates preclinical study and clinical trial expenses based on the services performed, pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered. The Company records upfront and milestone payments made to third parties under licensing arrangements as an expense. Upfront payments are recorded when incurred and milestone payments are recorded when the specific milestone has been achieved. Research and Development Services Internal and external research and development costs incurred in connection with collaboration agreements are recognized as revenue in the same period as the costs are incurred and are presented on a gross basis when the Company acts as a principal, has the discretion to choose suppliers, bears credit risk, and performs at least part of the services. Revenue Recognition The Company’s revenue to date has been generated primarily through license agreements and research and development collaboration agreements. The Company had no revenues for the years ending December 31, 2019 and 2018. Commencing January 1, 2018, the Company recognizes revenue in accordance with ASC 606. The core principle of ASC 606 is that an entity should recognize revenue to depict the transfer of promised goods and/or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and/or services. To determine the appropriate amount of revenue to be recognized for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following steps: (i) identify the contract(s) with the customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) each performance obligation is satisfied. Revenue under technology licenses and collaborative agreements typically consists of nonrefundable and/or guaranteed license fees, collaborative research funding, and various milestone and future product royalty or profit-sharing payments. These agreements are generally referred to as “multiple element arrangements”. The Company applies the accounting standard on revenue recognition for multiple element arrangements. The fair value of deliverables under the arrangement may be derived using a best estimate of selling price if vendor specific objective evidence and third-party evidence is not available. Deliverables under the arrangement will be separate units of accounting if a delivered item has value to the customer on a standalone basis and if the arrangement includes a general right of return for the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the Company’s control. The Company recognizes upfront license payments as revenue upon delivery of the license only if the license has standalone value from any undelivered performance obligations and that value can be determined. The undelivered performance obligations typically include manufacturing or development services or research and/or steering committee services. If the fair value of the undelivered performance obligations can be determined, then these obligations would be accounted for separately. If the license is not considered to have standalone value, then the license and other undelivered performance obligations would be accounted for as a single unit of accounting. In this case, the license payments and payments for performance obligations are recognized as revenue over the estimated period of when the performance obligations are performed or deferred indefinitely until the undelivered performance obligation is determined. Whenever the Company determines that an arrangement should be accounted for as a single unit of accounting, the Company determines the period over which the performance obligations will be performed, and revenue will be recognized. Revenue is recognized using a proportional performance or straight-line method. The proportional performance method is used when the level of effort required to complete performance obligations under an arrangement can be reasonably estimated. The amount of revenue recognized under the proportional performance method is determined by multiplying the total payments under the contract, excluding royalties and payments contingent upon achievement of milestones, by the ratio of the level of effort performed to date to the estimated total level of effort required to complete performance obligations under the arrangement. If the Company cannot reasonably estimate the level of effort to complete performance obligations under an arrangement, the Company recognizes revenue under the arrangement on a straight-line basis over the period the Company is expected to complete its performance obligations. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete its performance obligations under an arrangement. The Company’s collaboration agreements typically entitle the Company to additional payments upon the achievement of development, regulatory and sales performance-based milestones. If the achievement of a milestone is considered probable at the inception of the collaboration, the related milestone payment is included with other collaboration consideration, such as upfront fees and research funding, in the Company’s revenue calculation. Typically, these milestones are not considered probable at the inception of the collaboration. As such, milestones will typically be recognized in one of two ways depending on the timing of when the milestone is achieved. If the milestone is achieved during the performance period, then the Company will only recognize revenue to the extent of the proportional performance achieved at that date, or the proportion of the straight-line basis achieved at that date, and the remainder will be recorded as deferred revenue to be amortized over the remaining performance period. If the milestone is achieved after the performance period has completed and all performance obligations have been delivered, then the Company will recognize the milestone payment as Revenue in its entirety in the period the milestone was achieved. Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. The FASB subsequently issued ASU No. 2018-10 and 2018-11 in July 2018, which provide clarifications and improvements to ASU 2016-02 (collectively, the “new lease standard”). ASU No. 2018-11 provides the optional transition method which allows companies to apply the new lease standard at the adoption date instead of at the earliest comparative period presented and continue to apply the provisions of the previous lease standard in its annual disclosures for the comparative periods. The new lease standard requires lessees to present a right-of-use asset and a corresponding lease liability on the balance sheet. Additional footnote disclosures related to leases is also required. On January 1, 2019, the Company adopted the new lease standard using the optional transition method and certain other practical expedients. Under the practical expedient package elected, the Company is not required to reassess whether expired or existing contracts are or contain a lease; and is not required to reassess the lease classifications or reassess the initial direct costs associated with expired or existing leases. The new lease standard also provides practical expedients for an entity’s ongoing accounting. The Company elected the short-term lease recognition exemption for all leases that qualify. This means, for those leases that qualify, we will not recognize right of use assets or lease liabilities, and this includes not recognizing right of use assets or lease liabilities for existing short-term leases of those assets in transition. The Company elected the practical expedient to not separate lease and non-lease components for certain classes of assets. The Company sub-leases office-space under a short-term lease for $300 per month. Management has determined the lease term to be less than 12 months, including renewals, and therefore has not recorded a right-of-use asset and corresponding liability under the short-term lease recognition exemption. Lease costs for the years ended December 31, 2019 and 2018 totaled approximately $10,700 and $204,800, respectively and are included in the Consolidated Statements of Operations and Comprehensive Loss. Because the Company has elected to adopt the transitional practical expedients, Management was not required to reassess whether any existing or expired contracts contained embedded leases. The Company has not entered into any contracts during the 2019 fiscal year that contain an embedded lease. Stock-Based Compensation Expense The Company measures stock-based compensation expense for stock awards at the grant date, based on the fair value-based measurement of the award, and the expense is recorded over the related service period, generally the vesting period, net of estimated forfeitures. The Company calculates the fair value-based measurement of stock options using the Black-Scholes valuation model and the single-option method and recognizes expense using the straight-line attribution approach. Income Taxes The Company accounts for income taxes under an asset-and-liability approach. Deferred income taxes reflect the impact of temporary differences between assets and liabilities recognized for tax and financial reporting purposes measured by applying enacted tax rates and laws that will be in effect when the differences are expected to reverse, net operating loss carryforwards and tax credits. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company’s policy is to include interest and penalties related to unrecognized tax benefits within the Company’s provision for income taxes. Comprehensive Loss Comprehensive loss represents net loss adjusted for the change during the periods presented in unrealized gains and losses on available-for-sale securities less reclassification adjustments for realized gains or losses included in net loss. The unrealized gains or losses are reported on the Consolidated Statements of Operations and Comprehensive Loss. Net Loss Per Common Share Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, stock options, restricted stock units and common stock warrants are considered to be potentially dilutive securities but are excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods presented. The Company’s potential dilutive securities, which include stock options, restricted stock units and warrants have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per common share and be antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in all periods presented. The following shares subject to outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share as the effect of including such securities would be antidilutive: Year Ended December 31, 2019 2018 Options to purchase common stock 15,881,721 15,409,357 Warrants to purchase common stock 331,193 331,193 16,212,914 15,740,550 Segment Reporting The Company determines its segment reporting based upon the way the business is organized for making operating decisions and assessing performance. The Company operates in only one segment, which is related to the development of pharmaceutical products. Recent Accounting Pronouncements Until December 31, 2018, the Company qualified as an “emerging growth company” (“EGC”) pursuant to the provisions of the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”) and elected to take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act which permits EGCs to defer compliance with new or revised accounting standards until non-issuers are required to comply with such standards. A registrant with EGC status loses its eligibility as an EGC five years after its common equity initial public offering, or December 31, 2018 for the Company. Accordingly, the Company was required to adopt new accounting standards on the same timeline as other public companies effective January 1, 2018. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash”. ASU 2016-18 requires the inclusion of restricted cash with cash and cash equivalents when reconciling the beginning-of-the period and end-of-period total amounts shown on the statement of cash flows. The Company adopted the standard effective January 1, 2018. As a result of the adoption, the Company will no longer present the change within restricted cash in the consolidated statements of cash flows. See below for the composition of cash, cash equivalents and restricted cash shown on the statements of cash flow: Year Ended December 31, 2019 2018 Cash and cash equivalents $ 143 $ 814 Restricted cash 71 71 Total cash, cash equivalents and restricted cash as shown on statement of $ 214 $ 885 In June 2018, the FASB issued ASU 2018-07, “Compensation – Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting”. This ASU expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees and is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted. The Company adopted the standard effective January 1, 2019. The adoption of this standard did not have a material impact on the Company’s Consolidated Financial Statements and related disclosures. In November 2018, the FASB issued ASU No. 2018-18, “Collaborative Arrangements (Topic 808)—Clarifying the Interaction between Topic 808 and Topic 606”. ASU 2018-18 makes targeted improvements for collaborative arrangements by clarifying that certain transactions between collaborative arrangement participants should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer in the context of a unit of account. In those situations, all the guidance in Topic 606 should be applied, including recognition, measurement, presentation, and disclosure requirements. In addition, unit-of-account guidance in Topic 808 was aligned with the guidance in Topic 606 (that is, a distinct good or service) when an entity is assessing whether the collaborative arrangement or a part of the arrangement is within the scope of Topic 606. ASU 2018-18 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. The amendments in this Update should be applied retrospectively to the date of initial application of Topic 606. The Company is currently evaluating the requirements of ASU 2018-18 and has not yet determined its impact on the Company’s Consolidated Financial Statements and related disclosures.

Potentially Dilutive Securities

Potentially Dilutive Securities	3 Months Ended
	Mar. 31, 2020
Potentially Dilutive Securities
Potentially Dilutive Securities	3. Potentially Dilutive Securities The Company’s potentially dilutive securities, which include stock options, restricted stock units and warrants, have been excluded from the computation of diluted net loss per common share as the effect of including those securities would be to reduce the net loss per common share and be antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in each period presented. The following outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share: As of March 31, 2020 2019 Options to purchase common stock 17,104,649 16,062,922 Warrants to purchase common stock 331,193 331,193 17,435,842 16,394,115

Investments

Investments	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Investments	4. Investments At December 31, 2019, the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows: Gross Gross Amortized Unrealized Unrealized Cost Gains Losses Fair Value Money market funds $ 71 $ — $ — $ 71 Total investments $ 71 $ — $ — $ 71 Reported as: Cash and cash equivalents $ — Restricted cash 71 Total investments $ 71 At December 31, 2018 the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows: Gross Gross Amortized Unrealized Unrealized Cost Gains Losses Fair Value Money market funds $ 71 $ — $ — $ 71 Total investments $ 71 $ — $ — $ 71 Reported as: Cash and cash equivalents $ - Restricted cash, long-term 71 Total investments $ 71

Savant Arrangements

Savant Arrangements	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Savant Arrangements
Savant Arrangements	9. Savant Arrangements On June 30, 2016 the Company and Savant Neglected Diseases, LLC (“Savant”) entered into an Agreement for the Manufacture, Development and Commercialization of Benznidazole for Human Use (the “MDC Agreement”), pursuant to which the Company acquired certain worldwide rights relating to benznidazole (the “Compound”). In addition, on the Effective Date the Company and Savant also entered into a Security Agreement (the “Security Agreement”), pursuant to which the Company granted Savant a continuing senior security interest in the assets and rights acquired by the Company pursuant to the MDC Agreement and certain future assets developed from those acquired assets. On the Effective Date, the Company issued to Savant a five year warrant (the “Warrant”) to purchase 200,000 shares of the Company’s Common Stock, at an exercise price of $2.25 per share, subject to adjustment. The Warrant is exercisable for 25% of the shares immediately and exercisable for the remaining shares upon reaching certain regulatory related milestones. As of March 31, 2020 the number of shares for which the Warrant is currently exercisable totals 100,000 shares at an exercise price of $2.25 per share. As a result of the FDA granting accelerated and conditional approval of a benznidazole therapy manufactured by a competitor for the treatment of Chagas disease and awarding such competitor a neglected tropical disease PRV in August 2017, the Company ceased development of benznidazole and re-evaluated the final two vesting milestones and concluded that the probability of achievement of these milestones had decreased to 0%. In July 2017, the Company commenced litigation against Savant alleging that Savant breached the MDC Agreement and seeking a declaratory judgement. Savant has asserted counterclaims for breaches of contract under the MDC Agreement and the Security Agreement. The dispute primarily concerns the Company’s right under the MDC Agreement to offset certain costs incurred by the Company in excess of the agreed upon budget against payments due Savant. See Note 10, below, for more information regarding the Savant litigation. The aggregate cost overages as of June 30, 2017 that the Company asserts are Savant’s responsibility total approximately $3.4 million, net of a $0.5 million deductible. The Company asserts that it is entitled to offset $2.0 million in milestone payments due Savant against the cost overages, such that as of June 30, 2017, Savant owed the Company approximately $1.4 million. As of June 30, 2019, the cost overages totaled $4.1 million such that Savant owed the Company approximately $2.1 million in cost overages. Such cost overages have been charged to Research and development expense as incurred. Recovery of such cost overages, if any, will be recorded as a reduction of Research and development expense in the period received. The $2.0 million in milestone payments due Savant are included in Accrued expenses in the accompanying Condensed Consolidated Balance Sheet as of March 31, 2020 and December 31, 2019.	5. Savant Arrangements On February 29, 2016, the Company entered into a binding letter of intent (the “LOI”) with Savant Neglected Diseases, LLC (“Savant”). The LOI provided that the Company would acquire certain worldwide rights relating to benznidazole from Savant. On June 30, 2016, the Company and Savant entered into an Agreement for the Manufacture, Development and Commercialization of Benznidazole for Human Use (the “MDC Agreement”), pursuant to which the Company acquired certain worldwide rights relating to benznidazole. The MDC Agreement consummates the transactions contemplated by the LOI. In addition, on June 30, 2016, the Company and Savant also entered into a Security Agreement (the “Security Agreement”), pursuant to which the Company granted Savant a continuing senior security interest in the assets and rights acquired by the Company pursuant to the MDC Agreement and certain future assets developed from those acquired assets. On June 30, 2016, in connection with the MDC Agreement, the Company issued to Savant a five year warrant to purchase 200,000 shares of the Company’s Common Stock, at an exercise price of $2.25 per share, subject to adjustment. See Note 7. On May 26, 2017, the Company submitted its benznidazole Investigational New Drug Application (“IND”) to the Food and Drug Administration (“FDA”) which became effective on June 26, 2017. The Company recorded expense of $1.0 million during the year ended December 31, 2017 as Research and development expense related to the milestone achievement associated with the IND being declared effective. On July 10, 2017, FDA notified the Company that it granted Orphan Drug Designation to benznidazole for the treatment of Chagas disease. The Company recorded expense of $1.0 million during the year ended December 31, 2017 as Research and development expense related to the milestone achievement associated with Orphan Drug Designation. The $2.0 million in milestone payments due Savant are included in Accrued expenses in the accompanying Condensed Consolidated Balance Sheet as of December 31, 2019 and 2018. In July 2017, the Company commenced litigation against Savant alleging that Savant breached the MDC Agreement and seeking a declaratory judgement. Savant has asserted counterclaims for breaches of contract under the MDC Agreement and the Security Agreement. See Note 12 below for more information regarding the Savant litigation.

Debt

Debt	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Disclosure Text Block [Abstract]
Debt	4. Debt Notes Payable to Vendors On June 30, 2016, the Company issued promissory notes in an aggregate principal amount of approximately $1.2 million to certain claimants in accordance with the Company’s Plan of Reorganization (the “Plan”) filed with the United States Bankruptcy Court for the District of Delaware (the “Bankruptcy Court”) (Case No. 15-12628 (LSS) (the “Bankruptcy Case”) which became effective June 30, 2016, at which time the Company emerged from its Chapter 11 bankruptcy proceedings. The notes are unsecured, bear interest at 10% per annum and became due and payable in full, including principal and accrued interest on June 30, 2019. In July and August, 2019, following the receipt of proceeds from the 2019 Bridge Notes, the Company used approximately $0.5 million of the proceeds to retire a portion of these notes, including accrued interest. After giving effect to these payments, the aggregate principal amount and accrued but unpaid interest on these notes approximates $1.1 million as of March 31, 2020. As of March 31, 2020 and December 31, 2019, the Company has accrued $0.3 million and $0.3 million in interest related to these promissory notes, respectively. The outstanding principal amount and accrued but unpaid interest on these notes is currently payable to the respective holders without demand, notice or declaration, and the holders, without demand or notice of any kind, may exercise any and all other rights and remedies available to them under the notes, the Plan, at law or in equity. We do not have sufficient funds to repay the principal and accrued but unpaid interest on these notes in their entirety. Advance Notes In June, July and August, 2018 the Company received an aggregate of $0.9 million of proceeds from advances made to the Company (the “Advance Notes”) by four different lenders including Dr. Cameron Durrant, the Company’s Chairman and Chief Executive Officer; Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder; and Ronald Barliant, a director of the Company (collectively the “Lenders”). The Advance Notes accrued interest at a rate of 7% per year, compounded annually. In accordance with their terms, on May 30, 2019, in connection with the Company’s announcement of the Collaboration Agreement with Kite, the lenders converted the amounts due under the Advance Notes into the Company’s common stock at the conversion price of $0.45 per share. The Company issued a total of 2,179,622 shares of common stock in connection with the conversion. 2018 Convertible Notes Commencing September 19, 2018, the Company delivered a series of convertible promissory notes (the “2018 Notes”) evidencing an aggregate of $2.5 million of loans made to the Company by six different lenders, including an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder. The 2018 Notes bear interest at a rate of 7% per annum and will mature on the earliest of (i) twenty-four months from the date the 2018 Notes were signed, (ii) the occurrence of any customary event of default, or (iii) the certain liquidation events including any dissolution or winding up of the Company or merger or sale by the Company of all or substantially all of its assets (in any case, a “Liquidation Event”). The Company used the proceeds from the 2018 Notes for working capital. Following the end of the quarter ended March 31, 2020, holders of the 2018 Notes notified us of their exercise of their conversion rights. Please see Note 11 – Subsequent Events for additional information. As of March 31, 2020 and December 31, 2019, the Company has accrued $0.3 million and $0.2 million in interest related to these promissory notes, respectively. 2019 Convertible Notes Commencing on April 23, 2019, the Company delivered a series of convertible promissory notes (the “2019 Notes”) evidencing an aggregate of $1.3 million of loans made to the Company. The 2019 Notes bear interest at a rate of 7.5% per annum and will mature on the earliest of (i) twenty-four months from the date the 2019 Notes are signed (the “Stated Maturity Date”), (ii) the occurrence of any customary event of default, or (iii) the certain liquidation events including any dissolution or winding up of the Company or merger or sale by the Company of all or substantially all of its assets (in any case, a “Liquidation Event”). The Company used the proceeds from the 2019 Notes for working capital. Following the end of the quarter ended March 31, 2020, holders of the 2019 Notes notified us of their exercise of their conversion rights. Please see Note 11 – Subsequent Events for additional information. As of March 31, 2020 and December 31, 2019, the Company had accrued $0.1 million and $0.1 million in interest related to these promissory notes, respectively. The Advance Notes, the 2018 Notes and the 2019 Notes have an optional voluntary conversion feature in which the holder could convert the notes in the Company’s common stock at maturity at a conversion rate of $0.45 per share for the Advance Notes and the 2018 Notes and at a conversion rate of $1.25 for the 2019 Notes. The intrinsic value of this beneficial conversion feature was $1.8 million upon the issuance of the Advance Notes, the 2018 Notes and the 2019 Notes and was recorded as additional paid-in capital and as a debt discount which is accreted to interest expense over the term of the Advance Notes and Notes. Interest expense includes debt discount amortization of $0.2 million for the three months ended March 31, 2020. The Company evaluated the embedded features within the Advance Notes, the 2018 Notes and the 2019 Notes to determine if the embedded features are required to be bifurcated and recognized as derivative instruments. The Company determined that the Advance Notes, the 2018 Notes and the 2019 Notes contain contingent beneficial conversion features (“CBCF”) that allow or require the holder to convert the Advance Notes, the 2018 Notes and the 2019 Notes, as applicable, to Company common stock at a conversion rate of $0.45 per share for the Advance Notes and the 2018 Notes and $1.25 for the 2019 Notes, but did not contain embedded features requiring bifurcation and recognition as derivative instruments. Upon the occurrence of a CBCF that results in conversion of the Advance Notes, the 2018 Notes or the 2019 Notes to Company common stock, the remaining unamortized discount will be charged to interest expense. Upon conversion of the Advance Notes on May 30, 2019, the remaining unamortized discount was charged to interest expense. The remaining debt discount for the 2018 and 2019 will be charged to interest expense in the second quarter of 2020 with their conversion in April 2020. 2020 Convertible Redeemable Notes On March 13, 2020 and March 19, 2020 (the “Issuance Dates”), the Company delivered two convertible redeemable promissory notes (the “2020 Notes”) evidencing loans with an aggregate principal amount of $518,333 made to the Company. The 2020 Notes bear interest at a rate of 7.0% per annum and will mature on March 13, 2021 and March 19, 2021, respectively. The 2020 Notes contain an original issue discount of $33,000 and $18,833, respectively. The Company used the proceeds from the 2020 Notes for working capital. Beginning on the six month anniversary of the Issuance Dates, unless earlier redeemed by the Company, the holders are entitled, at their option, to convert all or any amount of the principal amount of the 2020 Notes then outstanding, together with the accrued and unpaid interest on such portion of the 2020 Notes proposed to be converted, into shares of the Company’s common stock (the "Common Stock") at a conversion price equal to $0.25 per share (the “Fixed Price”). After the nine month anniversary of the Issuance Dates, the conversion price shall be equal to the lower of (i) the Fixed Price or (ii) 68% of the lowest of either the trading price or closing bid of the Common Stock, for the ten prior trading days including the day upon which a Notice of Conversion is received (the “Variable Conversion Price”). In the event our Common Stock has a closing price equal to $0.30 or less for 5 consecutive days prior to the 9 month anniversary of the Issuance Date, then, beginning on the 6 month anniversary of the Issuance Date, the holders may elect in their respective Notice of Conversion to use the lower of the Fixed Price or the Variable Conversion Price set forth above. Commencing on the 6 month anniversary of the Issuance Dates, the Company will have the right, but not the obligation, to elect to make fixed monthly amortizing payments to the holders in the amount of $25,000 and $14,250, respectively. If we elect to make such payments, the holders shall not be entitled to convert all or any amount of the principal amount of the 2020 Notes then outstanding if and for so long as we are current in respect of the amortizing payments. The 2020 Notes may be redeemed by us at any time before the 270 th As of March 31, 2020, the Company has accrued $1,600 in interest related to the 2020 Notes. The Company evaluated the embedded features within the 2020 Notes and determined that the embedded features are required to be bifurcated and recognized as stand-alone derivative instruments. The variable-share settlement features within the 2020 Notes qualify as redemption features and meet the net settlement criterion for qualification as a stand-alone derivative. In determining the fair value of the bifurcated derivative, the Company evaluated the likelihood of conversion of the 2020 Notes to Company stock. As the Company believes it will have adequate funding prior to the six month anniversary of the 2020 Notes, the first conversion option for the holders of the 2020 Notes, and it has the intent to either begin making amortizing payments or to pay off the 2020 Notes in their entirety prior to that date, the fair value was determined to be $0 as of March 31, 2020. The original issue discount is being accreted to interest expense over the term of the 2020 Notes. Interest expense includes the original issue discount amortization of approximately $4,000 for the three months ended March 31, 2020. 2019 Bridge Notes On June 28, 2019, the Company issued three short-term, secured bridge notes (the “June Bridge Notes”) evidencing an aggregate of $1.7 million of loans made to the Company by three parties: Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder, lent $750,000; Nomis Bay LTD, the Company’s second largest stockholder, lent $750,000; and Dr. Cameron Durrant, the Company’s Chief Executive Officer and Chairman of the Board of Directors, lent $200,000. The proceeds from the June Bridge Notes were used to satisfy a portion of the unsecured obligations incurred in connection with the Company’s emergence from bankruptcy in 2016 and for working capital and general corporate purposes. Of the $1.7 million in proceeds received, $950,000 was received on June 28, 2019 and was recorded as Advance notes in the Condensed Consolidated Balance Sheet as of June 30, 2019. The remaining proceeds of $750,000 were received July 1, 2019 and recorded accordingly. The June Bridge Notes bear interest at a rate of 7.0% per annum and had an original maturity date of October 1, 2019, which the Company and the lenders agreed to extend until December 31, 2020. No other changes to the terms of the June Bridge Notes were made in connection with the extension of the maturity date. The June Bridge Notes may become due and payable at such earlier time as the Company raises more than $3,000,000 in a bona fide financing transaction or upon a change in control. The June Bridge Notes are secured by liens on substantially all of the Company’s assets. On November 12, 2019, the Company issued two short-term, secured bridge notes (the “November Bridge Notes” and together with the June Bridge Notes, the “2019 Bridge Notes”) evidencing an aggregate of $350,000 of loans made to the Company by two parties: Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., our controlling stockholder, lent $250,000; and Dr. Cameron Durrant, our Chief Executive Officer and Chairman of our Board of Directors, lent $100,000 The November Bridge Notes rank on par with the June Bridge Notes, and possess other terms and conditions substantially consistent with those notes. The November Bridge Notes bear interest at a rate of 7.0% per annum and had an original maturity date of December 31, 2019, which the Company and the lenders agreed to extend until December 31, 2020. No other changes to the terms of the November Bridge Notes were made in connection with the extension of the maturity date. The November Bridge Notes may become due and payable at such earlier time as the Company raises more than $3,000,000 in a bona fide financing transaction or upon a change in control. The November Bridge Notes also are secured by a lien on substantially all of the Company’s assets. Upon an event of default, which events include, but are not limited to, (1) the Company’s failure to timely pay any monetary obligation under the 2019 Bridge Notes; (2) our failure to pay our debts generally as they become due and (3) our commencing any proceeding relating to the Company under any bankruptcy reorganization, arrangement, insolvency, readjustment of debt, dissolution or liquidation or similar laws of any jurisdiction now or hereafter in effect, the interest payable on the 2019 Bridge Notes increases to 10.0% per annum. Further, upon certain events of default, all payments and obligations due and owed under the 2019 Bridge Notes shall immediately become due and payable without demand and without notice to the Company. As of March 31, 2020 and December 31, 2019, the Company has accrued $0.1 million and $0.1 million in interest related to these promissory notes, respectively. As of March 31, 2020, the maturities of the debt of the Company by year is as follows: Total 2020 2021 Principal payments on Notes payable to vendors $ 774 $ 774 $ - Interest payments on Notes payable to vendors 348 348 - Principal payments on 2019 Bridge notes 2,050 2,050 - Interest payments on 2019 Bridge notes 99 99 - Principal payments on Convertible notes 4,293 3,018 1,275 Interest payments on Convertible notes 358 270 88 Gross debt before unamortized discount 7,922 6,559 1,363 Unamortized debt discount on convertible debt (607 ) (532 ) (75 ) Total Debt $ 7,315 $ 6,027 $ 1,288	6. Debt Notes Payable to Vendors On June 30, 2016, the Company issued promissory notes in an aggregate principal amount of approximately $1.2 million to certain claimants in accordance with the Plan. The notes are unsecured, bear interest at 10% per annum and became due and payable in full, including principal and accrued interest on June 30, 2019. In July and August, 2019, following the receipt of proceeds from the 2019 Bridge Notes, the Company used approximately $0.5 million of the proceeds to retire a portion of these notes, including accrued interest. After giving effect to these payments, the aggregate principal amount and accrued but unpaid interest on these notes approximates $1.1 million as of December 31, 2019. As of December 31, 2019 and December 31, 2018, the Company has accrued $0.3 million and $0.3 million in interest related to these promissory notes, respectively. The outstanding principal amount and accrued but unpaid interest on these notes is currently payable to the respective holders without demand, notice or declaration, and the holders, without demand or notice of any kind, may exercise any and all other rights and remedies available to them under the notes, the Plan, at law or in equity. The Company does not have sufficient funds to repay the principal and accrued but unpaid interest on these notes in their entirety. Advance Notes In June, July and August, 2018, the Company received an aggregate of $0.9 million of proceeds from advances made to the Company (the “Advance Notes”) by four different lenders including Dr. Cameron Durrant, the Company’s Chairman and Chief Executive Officer; Cheval, an affiliate of BHC, the Company’s controlling stockholder; Ronald Barliant, a director of the Company; and an unrelated third party (collectively the “Advance Note Lenders”). The Advance Notes accrue interest at a rate of 7% per annum, compounded annually. The intention of the parties was that the amounts due under the Advance Notes would be converted automatically into the same type and class of securities as may be sold by the Company in a future financing transaction with an aggregate sales price of at least $5 million (a “Qualifying Financing”). The Advance Notes generally were not convertible at the option of the Advance Note Lenders into the Company’s common stock until June 21, 2019 (the “Expiration Date”); however, if prior to completing a Qualifying Financing, the Company experienced a change of control or made a public announcement that it had entered into a collaboration arrangement with a strategic partner relating to clinical studies of lenzilumab in connection with certain CAR-T therapies in a transaction that would not otherwise constitute a Qualifying Financing, the Advance Note Lenders could elect to convert the amounts due under the Advance Notes into the Company’s common stock at a conversion price of $0.45 per share. Additionally, if neither a Qualifying Financing nor a change of control had occurred by the Expiration Date, then at any time from and after the Expiration Date the Advance Note Lenders could, at their option, convert the Advance Notes, plus any accrued and unpaid interest, into a number of shares of the Company’s common stock at the lesser of (i) the volume weighted average sales price per share over the 20 most recent trading days prior to the conversion or (ii) $0.45 per share. In accordance with their terms, on May 30, 2019, in connection with the Company’s announcement of the Kite Agreement, the lenders converted the amounts due under the Advance Notes into the Company’s common stock at the conversion price of $0.45 per share. The Company issued a total of 2,179,622 shares of common stock in connection with the conversion. Convertible Notes 2018 Convertible Notes Commencing September 19, 2018, the Company delivered a series of convertible promissory notes (the “2018 Notes”) evidencing an aggregate of $2.5 million of loans made to the Company by six different lenders, including an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder. The 2018 Notes bear interest at a rate of 7% per annum and will mature on the earliest of (i) twenty-four months from the date the 2018 Notes were signed, (ii) the occurrence of any customary event of default, or (iii) the certain liquidation events including any dissolution or winding up of the Company or merger or sale by the Company of all or substantially all of its assets (in any case, a “Liquidation Event”). The Company used the proceeds from the 2018 Notes for working capital. The 2018 Notes are convertible into equity securities in the Company in three different scenarios: If the Company sells its equity securities on or before the date of repayment of the 2018 Notes in any financing transaction that results in gross proceeds to the Company of at least $10 million (a “Qualified Financing”), the 2018 Notes will be converted into either (i) such equity securities as the noteholder would acquire if the principal and accrued but unpaid interest thereon (the “Conversion Amount”) were invested directly in the financing on the same terms and conditions as given to the financing investors in the Qualified Financing, or (ii) common stock at a conversion price equal to $0.45 per share (subject to ratable adjustment for any stock split, stock dividend, stock combination or other recapitalization occurring subsequent to the date of the Notes). If the Company sells its equity securities on or before the date of repayment of the 2018 Notes in any financing transaction that results in gross proceeds to the Company of less than $10 million (a “Non-Qualified Financing”), the noteholders may convert their remaining 2018 Notes into either (i) such equity securities as the noteholder would acquire if the Conversion Amount were invested directly in the financing on the same terms and conditions as given to the financing investors in the Non-Qualified Financing, or (ii) common stock at a conversion price equal to $0.45 per share (subject to ratable adjustment for any stock split, stock dividend, stock combination or other recapitalization occurring subsequent to the date of the Notes). The 2018 Notes may convert in the event the Company enters into or publicly announces its intention to consummate a Liquidation Event. Immediately prior to the completion of any such Liquidation Event, in lieu of receiving payment in cash, noteholders may convert the Conversion Amount into common stock at a conversion price equal to $0.45 per share (subject to ratable adjustment for any stock split, stock dividend, stock combination or other recapitalization occurring subsequent to the date of the Notes). 2019 Convertible Notes Commencing on April 23, 2019, the Company delivered a series of convertible promissory notes (the “2019 Notes”) evidencing an aggregate of $1.3 million of loans made to the Company. The 2019 Notes bear interest at a rate of 7.5% per annum and will mature on the earliest of (i) twenty-four months from the date the 2019 Notes are signed (the “Stated Maturity Date”), (ii) the occurrence of any customary event of default, or (iii) the certain liquidation events including any dissolution or winding up of the Company or merger or sale by the Company of all or substantially all of its assets (in any case, a “Liquidation Event”). The Company used the proceeds from the 2019 Notes for working capital. The 2019 Notes are convertible into equity securities in the Company in four different scenarios: If the Company sells its equity securities on or before the Stated Maturity Date in any financing transaction that results in gross proceeds to the Company of at least $10.0 million (a “Qualified Financing”) or the Company consummates a reverse merger or similar transaction, the 2019 Notes will be converted into either (i) (a) in the case of a Qualified Financing, such equity securities as the noteholder would acquire if the principal and accrued but unpaid interest thereon together with such additional amount of interest as would have been paid on the 2019 Notes if held to the Stated Maturity Date (the “Conversion Amount”) were invested directly in the financing on the same terms and conditions (including price) as given to the financing investors in the Qualified Financing or (b) in the case of a reverse merger, common stock at the same price per share paid by the buyer in such transaction (which in a stock for stock transaction, shall be based on the price per share used by the parties for purposes of setting the applicable exchange ration), or (ii) common stock at a conversion price equal to $1.25 per share (subject to ratable adjustment for any stock split, stock dividend, stock combination or other recapitalization occurring subsequent to the date of the 2019 Notes). If the Company sells its equity securities on or before the date of repayment of the 2019 Notes in any financing transaction that results in gross proceeds to the Company of less than $ 10.0 million (a “Non-Qualified Financing”), the noteholders may convert their remaining Convertible Notes into either (i) such equity securities as the noteholder would acquire if the Conversion Amount were invested directly in the financing on the same terms and conditions (including price) as given to the financing investors in the Non-Qualified Financing, or (ii) common stock at a conversion price equal to $1.25 per share (subject to ratable adjustment for any stock split, stock dividend, stock combination or other recapitalization occurring subsequent to the date of the 2019 Notes). The 2019 Notes may convert in the event the Company enters into or publicly announces its intention to consummate a Liquidation Event. Immediately prior to the completion of any such Liquidation Event, in lieu of receiving payment in cash, noteholders may convert the Conversion Amount into common stock at a conversion price equal to $1.25 per share (subject to ratable adjustment for any stock split, stock dividend, stock combination or other recapitalization occurring subsequent to the date of the 2019 Notes). In addition, upon the six-month anniversary of the date the 2019 Notes are signed or such earlier time as the Company publicly announces that it has entered into a definitive arrangement with an unaffiliated third party (a “Strategic Partner”) pursuant to which, among other things, such Strategic Partner may agree to collaborate with the Company in conducting a clinical study to assess the efficacy of the Company’s lenzilumab monoclonal antibody in reducing adverse effects from neurotoxicity and cytokine release syndrome when used as a companion therapy in certain CAR-T cell therapies, noteholders may convert any portion of the outstanding principal amount of the 2019 Notes, together with (a) any unpaid and accrued interest on such principal amount to the date the noteholder’s notice of the noteholder’s intention to convert is received by the Company (the “Notice Date”), and (b) such additional amount of interest as would have been paid on such principal amount from the Notice Date to the Stated Maturity Date, into common stock at a conversion price equal to $1.25 per share (subject to ratable adjustment for any stock split, stock dividend, stock combination or other recapitalization occurring subsequent to the date of the 2019 Notes). The Company’s announcement of the Kite Agreement satisfied this requirement and accordingly, the 2019 Notes are convertible into common stock on the above terms. The Advance Notes, the 2018 Notes and the 2019 Notes have an optional voluntary conversion feature in which the holder could convert the notes in the Company’s common stock at maturity at a conversion rate of $0.45 per share for the Advance Notes and the 2018 Notes and at a conversion rate of $1.25 for the 2019 Notes. The intrinsic value of this beneficial conversion feature was $1.9 million upon the issuance of the Advance Notes, the 2018 Notes and the 2019 Notes and was recorded as additional paid-in capital and as a debt discount which is accreted to interest expense over the term of the Advance Notes and Notes. Interest expense includes debt discount amortization of $0.8 million and $0.3 million for the years ended December 31, 2019 and 2018, respectively. Total interest expense for the Advance Notes, the 2018 Notes and the 2019 Notes for the years ended December 31, 2019 and 2018, excluding the debt discount amortization was $0.3 and $0.1 million, respectively. The Company evaluated the embedded features within the Advance Notes, the 2018 Notes and the 2019 Notes to determine if the embedded features are required to be bifurcated and recognized as derivative instruments. The Company determined that the Advance Notes, the 2018 Notes and the 2019 Notes contain contingent beneficial conversion features (“CBCF”) that allow or require the holder to convert the Advance Notes, the 2018 Notes and the 2019 Notes, as applicable, to Company common stock at a conversion rate of $0.45 per share for the Advance Notes and the 2018 Notes and $1.25 for the 2019 Notes, but did not contain embedded features requiring bifurcation and recognition as derivative instruments. Upon the occurrence of a CBCF that results in conversion of the Advance Notes, the 2018 Notes or the 2019 Notes to Company common stock, the remaining unamortized discount will be charged to interest expense. Upon conversion of the Advance Notes on May 30, 2019, the remaining unamortized discount was charged to interest expense. The remaining debt discount will be amortized over 9 and 16 months for the 2018 Notes and the 2019 Notes, respectively. 2019 Bridge Notes On June 28, 2019, the Company issued three short-term, secured bridge notes (the “June Bridge Notes”) evidencing an aggregate of $1.7 million of loans made to the Company by three parties: Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder, lent $750,000; Nomis Bay LTD, the Company’s second largest stockholder, lent $750,000; and Cameron Durrant, M.D., MBA, the Company’s Chief Executive Officer and Chairman of the Board of Directors, lent $200,000. The proceeds from the June Bridge Notes were used to satisfy a portion of the unsecured obligations incurred in connection with the Company’s emergence from bankruptcy in 2016 and for working capital and general corporate purposes. Of the $1.7 million in proceeds received, $950,000 was received on June 28, 2019 and was recorded as Advance notes in the Condensed Consolidated Balance Sheet as of June 30, 2019. The remaining proceeds of $750,000 were received July 1, 2019 and recorded accordingly. The June Bridge Notes bear interest at a rate of 7.0% per annum and had an original maturity date of October 1, 2019. On October 8, 2019, the Company and the lenders agreed to extend the maturity date of the June Bridge Notes from October 1, 2019 until December 31, 2019 and to waive any prior default up to and including the date of the amendment. On December 30, 2019, the Company and the lenders agreed to extend the maturity date of the June Bridge Notes from December 31, 2019 until March 31, 2020. No other changes to the terms of the June Bridge Notes were made in connection with the extension of the maturity date. The June Bridge Notes may become due and payable at such earlier time as the Company raises more than $3,000,000 in a bona fide financing transaction or upon a change in control. The June Bridge Notes are secured by liens of substantially all of the Company’s assets. On November 12, 2019, he Company issued two short-term, secured bridge notes (the “November Bridge Notes” and together with the June Bridge Notes, the “2019 Bridge Notes”) evidencing an aggregate of $350,000 of loans made to the Company by two parties: Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., our controlling stockholder, lent $250,000; and Cameron Durrant, M.D., MBA, our Chief Executive Officer and Chairman of our Board of Directors, lent $100,000 The November Bridge Notes rank on par with the June Bridge Notes, and possess other terms and conditions substantially consistent with those notes. The November Bridge Notes bear interest at a rate of 7.0% per annum and had an original maturity date of December 31, 2019. On December 30, 2019, the Company and the lenders agreed to extend the maturity date of the November Bridge Notes from December 31, 2019 until March 31, 2020. No other changes to the terms of the November Bridge Notes were made in connection with the extension of the maturity date. The November Bridge Notes may become due and payable at such earlier time as the Company raises more than $3,000,000 in a bona fide financing transaction or upon a change in control. The November Bridge Notes also are secured by a lien of substantially all of the Company’s assets. Upon an event of default, which events include, but are not limited to, (1) the Company’s failure to timely pay any monetary obligation under the 2019 Bridge Notes; (2) our failure to pay our debts generally as they become due and (3) our commencing any proceeding relating to the Company under any bankruptcy reorganization, arrangement, insolvency, readjustment of debt, dissolution or liquidation or similar laws of any jurisdiction now or hereafter in effect, the interest payable on the 2019 Bridge Notes increases to 10.0% per annum. Further, upon certain events of default, all payments and obligations due and owed under the 2019 Bridge Notes shall immediately become due and payable without demand and without notice to the Company. Total interest expense for the 2019 Bridge Notes for the year ended December 31, 2019 was $0.1 million. As of December 31, 2019, the maturities of the debt of the Company by year is as follows: Total 2020 2021 Principal payments on Notes payable to vendors $ 774 $ 774 $ - Interest payments on Notes payable to vendors 320 320 - Principal payments on 2019 Bridge notes 2,050 2,050 - Interest payments on 2019 Bridge notes 63 63 - Principal payments on Convertible notes 3,775 2,500 1,275 Interest payments on Convertible notes 290 224 66 Gross debt before unamortized discount 7,272 5,931 1,341 Unamortized debt discount on convertible debt (785 ) (691 ) (94 ) Total Debt $ 6,487 $ 5,240 $ 1,247

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	5. Derivative Instruments The Company has certain embedded equity conversion features within its 2020 Notes that require bifurcation and recognition as stand-alone derivatives. See Note 4 – Debt for additional information and discussion on the bifurcated derivatives.

Warrants to Purchase Common Sto

Warrants to Purchase Common Stock	12 Months Ended
	Dec. 31, 2019
Warrants to Purchase Common Stock
Warrants to Purchase Common Stock	7. Warrants to Purchase Common Stock On June 19, 2013, the Company issued a warrant to purchase up to an aggregate of 6,193 shares of common stock and an exercise price of $96.88 per share. The warrant expires on the tenth anniversary of its issuance date. As of December 31, 2019, these warrants were fully vested. On December 4, 2015, the Company issued a warrant to purchase up to an aggregate of 125,000 shares of common stock at an exercise price of $29.32 per share. The warrant expires on the fifth anniversary of its issuance. As of December 31, 2019, these warrants were fully vested. On June 30, 2016, in connection with the MDC Agreement described in Note 5, the Company issued to Savant a five year warrant (the “Savant Warrant”) to purchase 200,000 shares of the Company’s Common Stock, at an exercise price of $2.25 per share, subject to adjustment. The Savant Warrant is exercisable for 25% of the shares immediately and exercisable for the remaining shares upon reaching certain regulatory related milestones. In addition, pursuant to the MDC Agreement, the Company has granted Savant certain “piggyback” registration rights for the shares issuable under the Savant Warrant. The Company determined the initial fair value of the Savant Warrant to be approximately $0.7 million as of June 30, 2016. The Company reevaluated the performance conditions and expected vesting of the Warrant quarterly during 2017 and 2018 and recorded a reduction of expense of approximately $0.1 million during the year ended December 31, 2017. The expense reduction was due to a decline in the fair value, which reduction is included in Research and development expenses in the accompanying Condensed Consolidated Statement of Operations and Comprehensive Loss. Specifically, as a result of the FDA granting accelerated and conditional approval of a benznidazole therapy manufactured by the Chemo Group (“Chemo”) for the treatment of Chagas disease and awarding Chemo a neglected tropical disease PRV, the Company re-evaluated the final two vesting milestones and concluded that the probability of achievement of these milestones had decreased to 0%. As of December 31, 2019, 100,000 of these warrants were fully vested and 100,000 were not vested. The Company will continue to reevaluate the performance conditions and expected vesting of the Savant Warrant on a quarterly basis until all performance conditions have been met or the warrants expire.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Contractual Obligations and Commitments As of March 31, 2020, other than the debt issuances described in Note 4 and the license agreements described in Note 8, there were no material changes to the Company’s contractual obligations from those set forth in the 2019 Form 10-K. Guarantees and Indemnifications The Company has certain agreements with service providers with which it does business that contain indemnification provisions pursuant to which the Company typically agrees to indemnify the party against certain types of third-party claims. The Company accrues for known indemnification issues when a loss is probable and can be reasonably estimated. The Company would also accrue for estimated incurred but unidentified indemnification issues based on historical activity. As the Company has not incurred any indemnification losses to date, there were no accruals for or expenses related to indemnification issues for any period presented.	8. Commitments and Contingencies Operating Leases The Company leased office space in Brisbane, California under an operating lease agreement that expired in September 2018. In May 2018, the Company entered into a month-to-month lease for office space in Burlingame, California. The Company terminated the lease on November 19, 2019 and entered into a sub-lease agreement for space in the same building in Burlingame, California. The sub-lease initial term expires on March 31, 2020 and is renewable for additional terms by mutual agreement. As of December 31, 2019, the Company had no significant future minimum lease payments. Rent expense was $0.01 million and $0.2 million for the years ended December 31, 2019 and December 31, 2018, respectively. Indemnification The Company has certain agreements with service providers with which it does business that contain indemnification provisions pursuant to which the Company typically agrees to indemnify the party against certain types of third-party claims. The Company accrues for known indemnification issues when a loss is probable and can be reasonably estimated. The Company would also accrue for estimated incurred but unidentified indemnification issues based on historical activity. As the Company has not incurred any indemnification losses to date, there were no accruals for or expenses related to indemnification issues for any period presented.

Stockholders' Equity

Stockholders' Equity	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Lincoln Park Capital Purchase Agreement On November 8, 2019, the Company entered into a purchase agreement (the “Purchase Agreement”) and a registration rights agreement (the “Registration Rights Agreement”) with Lincoln Park Capital Fund, LLC (“LPC”), pursuant to which the Company has the right to sell to LPC up to $20,000,000 in shares of the Company’s common stock, $0.001 par value per share (the “Common Stock”), subject to certain limitations and conditions set forth in the Purchase Agreement. Under the Purchase Agreement, the Company has the right, from time to time at its sole discretion and subject to certain conditions, to direct LPC to purchase up to 100,000 shares of Common Stock, with such amounts increasing based on certain threshold prices but not to exceed $750,000 in total proceeds on any purchase date. The purchase price of shares of Common Stock pursuant to the Purchase Agreement will be based on the market prices of the Common Stock at the time of such purchases as set forth in the Purchase Agreement. Such sales of Common Stock by the Company, if any, may occur from time to time, at the Company’s option, over the 36-month period expiring in December 2022. In connection with the signing of the Purchase Agreement on November 8, 2019, the Company issued 706,592 shares of its common stock to LPC. The issuance of the shares were recorded as debt issuance costs in Common stock and Additional paid-in capital with no net effect on Stockholders’ deficit. In addition to regular purchases, as described above, the Company may also direct LPC to purchase additional amounts as accelerated purchases if the closing sale price of the Common Stock is not below certain threshold prices, as set forth in the Purchase Agreement. In all instances, the Company may not sell shares of its Common Stock to LPC under the Purchase Agreement if it would result in LPC beneficially owning more than 4.99% of the Common Stock then outstanding. LPC represented to the Company, among other things, that it was an “accredited investor” (as such term is defined in Rule 501(a) of Regulation D under the Securities Act of 1933, as amended (the “Securities Act”)), and the Company sold the securities to LPC pursuant to the exemption for transactions by an issuer not involving any public offering under Section 4(a)(2) of, and Regulation D under, the Securities Act. The Purchase Agreement and the Registration Rights Agreement contain customary representations, warranties, agreements and conditions to completing future sale transactions, indemnification rights and obligations of the parties. The Company has the right to terminate the Purchase Agreement at any time, at no cost or penalty. During any “event of default” under the Purchase Agreement, all of which are outside of LPC’s control, LPC does not have the right to terminate the Purchase Agreement; however, the Company may not initiate any regular or other sale of shares to LPC until such event of default is cured. Actual sales of shares of Common Stock to LPC under the Purchase Agreement will depend on a variety of factors to be determined by the Company from time to time, including, among others, market conditions, the trading price of the Common Stock and determinations by the Company as to the appropriate sources of funding for the Company and its operations. In consideration for entering in the Purchase Agreement, the Company paid LPC a commitment fee in shares of Common Stock. The Company did not receive any cash proceeds from the issuance of these shares. The net proceeds under the Purchase Agreement to the Company will depend on the frequency and prices at which the Company sells shares of its stock to LPC. The Company expects that any proceeds received by the Company from such sales to LPC will be used for working capital and general corporate purposes. During the months of December 2019 and January 2020, the Company issued a total of 700,000 shares for aggregate proceeds of $0.3 million under the Purchase Agreement. Equity Financings During the month of December 2019, the Company issued 500,000 shares of its common stock for aggregate proceeds of $0.2 million under the Purchase Agreement. During the month of January 2020, the Company issued 200,000 shares of its common stock for aggregate proceeds of $0.1 million under the Purchase Agreement. 2012 Equity Incentive Plan Under the Company’s 2012 Equity Incentive Plan, the Company may grant shares, stock units, stock appreciation rights, performance cash awards and/or options to employees, directors, consultants, and other service providers. For options, the per share exercise price may not be less than the fair market value of a Company common share on the date of grant. Awards generally vest and become exercisable over three to four years and expire 10 years from the date of grant. Options generally become exercisable as they vest following the date of grant. A summary of stock option activity for the three months ended March 31, 2020 under all of the Company’s options plans is as follows: Options Weighted Outstanding at January 1, 2020 15,881,721 $ 0.95 Granted 1,223,033 0.40 Exercised - - Cancelled (forfeited) - - Cancelled (expired) (105 ) 11.68 Outstanding at March 31, 2020 17,104,649 $ 0.91 The weighted average fair value of options granted during the three months ended March 31, 2020 was $0.40 per share. The Company valued the options granted using the Black-Scholes options pricing model and the following weighted-average assumption terms for the three months ended : Three months ended March 31, 2020 Exercise price $0.38 - $0.40 Market value $0.38 - $0.40 Expected term 5 years Expected volatility 95% Risk-free interest rate 1.47% - 1.57% Expected dividend yield 0% Stock-Based Compensation The Company recorded stock-based compensation expense in the Condensed Consolidated Statements of Operations as follows: Three months ended March 31, 2020 2019 General and administrative $ 211 $ 697 Research and development 54 - Total stock-based compensation $ 265 $ 697 At March 31, 2020, the Company had $0.7 million of total unrecognized stock-based compensation expense, net of estimated forfeitures, related to outstanding stock options that will be recognized over a weighted-average period of 1.6 years.	9. Stockholders’ Equity Restructuring Transactions On December 1, 2017, the Company’s obligations matured under the Credit and Security Agreement dated December 21, 2016, as amended on March 21, 2017 and on July 8, 2017 (the “Term Loan Credit Agreement”) with BHCMF, as administrative agent and lender, BHC, as a lender, Cheval, as a lender (collectively with BHCMF and BHC, the Black Horse Entities) and Nomis Bay LTD, as a lender (Nomis and, together with the Black Horse Entities, the Term Loan Lenders). On December 21, 2017, the Company entered into a Securities Purchase and Loan Satisfaction Agreement (the “Purchase Agreement”) and a Forbearance and Loan Modification Agreement (the “Forbearance Agreement” and, together with the Purchase Agreement, the “Restructuring Agreements”), each with the Term Loan Lenders, in connection with a series of transactions providing for, among other things, the satisfaction and extinguishment of the Company’s outstanding obligations under the Term Loan Credit Agreement and the infusion of $3.0 million of new capital. As of February 27, 2018, the date the Restructuring Transactions were completed, the aggregate amount of our obligations under the Term Loan Credit Agreement, including the Bridge Loan, the Claims Advances extended by Nomis Bay (each as discussed below) and all accrued interest and fees, approximated $18.4 million (the “Term Loans”). On February 27, 2018 (the “Restructuring Effective Date”), the Restructuring Transactions were completed in accordance with the Restructuring Agreements. As a result, on the Restructuring Effective Date, the Company: (i) in exchange for the satisfaction and extinguishment of the entire $18.4 million balance of the Term Loans, including the Bridge Loan, the Claims Advances extended by Nomis Bay (each as discussed below) and all accrued interest and fees, (a) issued to the Term Loan Lenders an aggregate of 59,786,848 shares of its common stock (the “New Lender Shares”), and (b) transferred and assigned to Madison Joint Venture LLC owned 70% by Nomis Bay and 30% by the Company (Madison), all of the Company’s assets related to benznidazole (the Benz Assets), the Company’s former drug candidate, capable of being so assigned; and (ii) issued to Cheval an aggregate of 32,028,669 shares of common stock (the “New Black Horse Shares” and, collectively with the New Lender Shares, the “New Common Shares”) for total consideration of $3.0 million (collectively, the “Restructuring Transactions”), $1.5 million of which the Company received on December 22, 2017 in the form of a bridge loan (the “Bridge Loan”). On the Restructuring Effective Date, the aggregate amount of the Term Loans that were deemed to be satisfied and extinguished (i) previously owed to the Black Horse Entities, including the Bridge Loan and all accrued interest and fees, approximated $9.9 million, and (ii) previously owed to Nomis Bay, including certain advances previously extended to the Company by Nomis Bay totaling $0.1 million (the “Claims Advances”) and all accrued interest and fees, approximated $8.5 million. In addition, on the Restructuring Effective Date, (i) each of the Term Loan Credit Agreement, all promissory notes issued thereunder and the Intellectual Property Security Agreement, dated as of December 21, 2016, by and between the Company and the Term Loan Lenders, were terminated and are of no further force or effect, and (ii) all security interests of the Black Horse Entities and Nomis Bay in the Company’s assets were released. Although the Term Loans were satisfied and extinguished, if Madison elected to keep the Benz Assets after the Restructuring Effective Date, Nomis Bay would be obligated to pay or cause Madison to pay $0.3 million in legal fees and expenses owed by the Company to its litigation counsel, which remained unpaid in Accounts payable at December 31, 2017. On August 23, 2018 Madison elected to keep the Benz Assets and these amounts were paid by Madison to the Company’s litigation counsel. Upon completion of the Restructuring Transactions, Nomis Bay held 33,573,530 of the Company’s common stock, or approximately 31.4% of its outstanding common stock, and the Black Horse Entities collectively held 66,870,851 shares of the Company’s common stock, or approximately 62.6% of its outstanding common stock. Accordingly, the completion of the Restructuring Transactions on the Restructuring Effective Date resulted in a change in control of the Company, as the Black Horse Entities and their affiliates owning more than a majority of its outstanding common stock. Dr. Dale Chappell, a member of the Company’s board of directors from June 30, 2016 until November 10, 2017, controls the Black Horse Entities and accordingly, will be able to exert control over matters of the Company and will be able to determine all matters of the Company requiring stockholder approval. Lincoln Park Capital Purchase Agreement On November 8, 2019, the Company entered into a purchase agreement (the “Purchase Agreement”) and a registration rights agreement (the “Registration Rights Agreement”) with Lincoln Park Capital Fund, LLC (“LPC”), pursuant to which the Company has the right to sell to LPC up to $20,000,000 in shares of the Company’s common stock, $0.001 par value per share (the “Common Stock”), subject to certain limitations and conditions set forth in the Purchase Agreement. Under the Purchase Agreement, the Company has the right, from time to time at its sole discretion and subject to certain conditions, to direct LPC to purchase up to 100,000 shares of Common Stock, with such amounts increasing based on certain threshold prices but not to exceed $750,000 in total proceeds on any purchase date. The purchase price of shares of Common Stock pursuant to the Purchase Agreement will be based on the market prices of the Common Stock at the time of such purchases as set forth in the Purchase Agreement. Such sales of Common Stock by the Company, if any, may occur from time to time, at the Company’s option, over the 36-month period expiring in December 2022. In connection with the signing of the Purchase Agreement on November 8, 2019, the Company issued 706,592 shares of its common stock to LPC. The issuance of the shares were recorded as debt issuance costs in Common stock and Additional paid-in capital with no net effect on Stockholders’ deficit. In addition to regular purchases, as described above, the Company may also direct LPC to purchase additional amounts as accelerated purchases if the closing sale price of the Common Stock is not below certain threshold prices, as set forth in the Purchase Agreement. In all instances, the Company may not sell shares of its Common Stock to LPC under the Purchase Agreement if it would result in LPC beneficially owning more than 4.99% of the Common Stock then outstanding. LPC represented to the Company, among other things, that it was an “accredited investor” (as such term is defined in Rule 501(a) of Regulation D under the Securities Act of 1933, as amended (the “Securities Act”)), and the Company sold the securities to LPC pursuant to the exemption for transactions by an issuer not involving any public offering under Section 4(a)(2) of, and Regulation D under, the Securities Act. The Purchase Agreement and the Registration Rights Agreement contain customary representations, warranties, agreements and conditions to completing future sale transactions, indemnification rights and obligations of the parties. The Company has the right to terminate the Purchase Agreement at any time, at no cost or penalty. During any “event of default” under the Purchase Agreement, all of which are outside of LPC’s control, LPC does not have the right to terminate the Purchase Agreement; however, the Company may not initiate any regular or other sale of shares to LPC until such event of default is cured. Actual sales of shares of Common Stock to LPC under the Purchase Agreement will depend on a variety of factors to be determined by the Company from time to time, including, among others, market conditions, the trading price of the Common Stock and determinations by the Company as to the appropriate sources of funding for the Company and its operations. In consideration for entering in the Purchase Agreement, the Company has agreed to pay to LPC a commitment fee in shares of Common Stock. The Company will not receive any cash proceeds from the issuance of these shares. The net proceeds under the Purchase Agreement to the Company will depend on the frequency and prices at which the Company sells shares of its stock to LPC. The Company expects that any proceeds received by the Company from such sales to LPC will be used for working capital and general corporate purposes. On November 20, 2019, the Company filed a registration statement on Form S-1. The registration statement was declared effective on December 2, 2019 and the Company filed a final prospectus on December 4, 2019. Other Common Stock Transactions Equity Financings On March 12, 2018, the Company issued 2,445,557 shares of its common stock for total proceeds of $1.1 million to accredited investors. On June 4, 2018, the Company issued 400,000 shares of its common stock for total proceeds of $0.2 million to an accredited investor. In February 2018, the Company amended and restated its certificate of incorporation to increase the authorized common stock to 225,000,000 shares and authorized 25,000,000 shares of preferred stock. During the month of December 2019, the Company issued 500,000 shares of its common stock for aggregate proceeds of $0.2 million under the Purchase Agreement. The Company has reserved the following shares of common stock for issuance as of December 31, 2019: Warrants to purchase common stock 331,193 Options: Outstanding under the 2012 Equity Incentive Plan 15,881,406 Outstanding under the 2001 Equity Incentive Plan 315 Available for future grants under the 2012 Equity Incentive Plan 3,050,799 Shares reserved under the 2019 LPC Purchase Agreement 14,500,000 Total common stock reserved for future issuance 33,763,713 2012 Equity Incentive Plan Under the Company’s 2012 Equity Incentive Plan, the Company may grant shares, stock units, stock appreciation rights, performance cash awards and/or options to employees, directors, consultants, and other service providers. For options, the per share exercise price may not be less than the fair market value of a Company common share on the date of grant. Awards generally vest and become exercisable over three to four years and expire 10 years from the date of grant. Options generally become exercisable as they vest following the date of grant. In general, to the extent that awards under the 2012 Plan are forfeited or lapse without the issuance of shares, those shares will again become available for awards. The 2012 Plan will continue in effect for 10 years from its adoption date, unless the Company’s board of directors decides to terminate the plan earlier. On September 13, 2016, the Board of Directors of the Company approved an amendment to the Company’s 2012 Equity Incentive Plan to increase the number of shares of the Company’s common stock available for issuance under the Plan by 3,000,000 shares and to increase the annual maximum aggregate number of shares subject to stock option awards that may be granted to any one person under the Plan from 125,000 to 1,100,000. On March 9, 2018, the Board of Directors of the Company approved an amendment to the Company’s 2012 Equity Incentive Plan (the “Equity Plan”) to increase the number of shares of the Company’s common stock authorized for issuance under the Equity Plan by 16,050,000 shares, and to increase the annual maximum aggregate number of shares subject to stock option awards that may be granted to any one person under the Equity Plan during a calendar year to 7,500,000. As of December 31, 2019, there were 3,050,799 shares available for grant under the 2012 Equity Incentive Plan. 2001 Equity Incentive Plan Under the Company’s 2001 Stock Plan (the “2001 Plan”), the Company was able to grant shares and/or options to purchase up to 426,030 shares of common stock to employees, directors, consultants, and other service providers. In connection with the 2012 Plan taking effect, the 2001 Plan was terminated in August 2012. However, the awards under the 2001 Plan outstanding as of the termination of the 2001 Plan continued to be governed by their existing terms. Stock Option Activity The following table summarizes stock option activity for the years ended December 31, 2019 and 2018: Number of Weighted Weighted- Aggregate Outstanding at January 1, 2018 2,448,383 $ 4.15 Granted 13,575,038 0.66 Cancelled (forfeited) (572,935 ) 3.20 Cancelled (expired) (41,129 ) 37.82 Outstanding at December 31, 2018 15,409,357 0.95 Granted 1,470,957 0.78 Exercised (488,625 ) 0.67 Cancelled (forfeited) (509,923 ) 0.62 Cancelled (expired) (45 ) 9.68 Outstanding at December 31, 2019 15,881,721 $ 0.95 8.2 $ 49 Options vested and expected to vest 15,827,723 $ 0.95 8.2 $ 49 Exercisable 13,661,670 $ 0.99 8.0 $ 22 (1) The weighted average price per share is determined using exercise price per share for stock options. (2) The aggregate intrinsic value is calculated as the difference between the exercise price of the option and the fair value of the Company’s common stock for in-the-money options at December 31, 2019. The stock options outstanding and exercisable by exercise price at December 31, 2019 are as follows: Stock Options Outstanding Stock Options Exercisable Range of Exercise Prices Number of Weighted- Weighted- Number of Weighted- $0.33 - $0.67 13,442,367 8.28 $ 0.65 11,533,358 $ 0.66 $0.84 - $1.30 755,080 9.15 $ 1.09 445,705 $ 0.94 $1.91 - $3.30 370,000 7.10 $ 2.97 368,333 $ 2.97 $3.38 - $3.38 1,263,022 6.71 $ 3.38 1,263,022 $ 3.38 $3.40 - $4.72 50,625 6.77 $ 3.40 50,625 $ 3.40 $8.24 - $17.36 315 1.02 $ 12.94 315 $ 12.94 $42.88 - $48.00 312 3.76 $ 45.17 312 $ 45.17 15,881,721 8.17 $ 0.95 13,661,670 $ 0.99 The total fair value of options vested for the years ended December 31, 2019 and 2018 was $2.0 million and $4.8 million, respectively. Stock-Based Compensation The Company’s stock-based compensation expense for stock options is estimated at the grant date based on the award’s fair value as calculated by the Black-Scholes option pricing model and is recognized as expense over the requisite service period. The Black-Scholes option pricing model requires various highly judgmental assumptions including expected volatility and expected term. The expected volatility is based on the historical stock volatilities of several of the Company’s publicly listed peers over a period equal to the expected terms of the options as the Company does not have a sufficient trading history to use the volatility of its own common stock. To estimate the expected term, the Company has opted to use the simplified method, which is the use of the midpoint of the vesting term and the contractual term. If any of the assumptions used in the Black-Scholes option pricing model changes significantly, stock-based compensation expense may differ materially in the future from that recorded in the current period. In addition, the Company is required to estimate the expected forfeiture rate and only recognize expense for those shares expected to vest. The Company estimates the forfeiture rate based on historical experience and its expectations regarding future pre-vesting termination behavior of employees. The Company reviews its estimate of the expected forfeiture rate annually, and stock-based compensation expense is adjusted accordingly. The weighted-average fair value-based measurement of stock options granted under the Company’s stock plans in the years ended December 31, 2019 and 2018 was $0.79 and $0.47 per share, respectively. The fair value- based measurement of stock options granted under the Company’s stock plans was estimated at the date of grant using the Black-Scholes model with the following assumptions: Year Ended December 31, 2019 2018 Expected term 5 - 6 years 5 - 6 years Expected volatility 96% - 99% 93% - 97% Risk-free interest rate 1.74% - 2.59% 2.7% - 2.8% Expected dividend yield 0% 0% Total expense for stock option grants recognized was as follows: Year ended December 31, 2019 2018 General and administrative $ 1,928 $ 4,611 Research and development 97 201 Total stock-based compensation $ 2,025 $ 4,812 At December 31, 2019, the Company had $1.0 million of total unrecognized compensation expense, net of estimated forfeitures, related to outstanding stock options that will be recognized over a weighted-average period of 1.4 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes No provision for federal income taxes has been recorded for the years ended December 31, 2019 and 2018 due to net losses and the valuation allowance established. Deferred tax assets and liabilities reflect the net tax effects of net operating loss and tax credit carryovers and the temporary differences between the carrying amounts of assets and liabilities for financial reporting and the amounts used for income tax purposes. Significant components of the Company's deferred tax assets are as follows: As of December 31, 2019 2018 Deferred tax assets: Net operating losses $ 50,144 $ 47,877 Research and other credits 2,178 2,178 Stock based compensation 3,001 2,682 In-Process research and development 1,253 1,314 Other 854 708 Total deferred tax assets 57,430 54,759 Valuation allowance (57,430 ) (54,759 ) Net deferred tax assets $ - $ - A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 2019 and 2018 is as follows: Year Ended December 31, 2019 2018 Statutory rate 21.0 % 21.0 % Valuation allowance (26.0 )% (26.4 )% Nondeductible stock compensation (0.3 )% 0.1 % Other 5.3 % 5.3 % Effective tax rate - % - % Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $2.7 million during 2019 and increased by $3.2 million during 2018. At December 31, 2019, the Company had federal net operating loss carryforwards of approximately $166.2 million, which expire in the years 2021 through 2037, and state net operating loss carryforwards of approximately $172 million, which expire in the years 2028 through 2039. The Company also has federal net operating loss carryforwards generated in 2018 and 2019 of $15.4 million that have no expiration date as a result of the December 22, 2017 Tax Cuts and Jobs Act tax reform legislation. At December 31, 2019, the Company had federal research and development credit carryforwards of approximately $1.3 million, which expire in the years 2022 through 2035 and state research and development credit carryforwards of approximately $2.2 million. The state research and development credit carryforwards can be carried forward indefinitely. During 2013, the Company completed a Section 382 study in accordance with the Internal Revenue Code of 1986, as amended, and similar state provisions. The study concluded that the Company has experienced several ownership changes since inception. This causes the Company's utilization of its net operating loss and tax credit carryforwards to be subject to substantial annual limitations. These results are reflected in the above carryforward amounts and deferred tax assets. The Company's ability to utilize its net operating loss and tax credit carryforwards are further limited as a result of subsequent ownership changes. All such limitations could result in the expiration of carryforwards before they are utilized. An ownership change may have occurred during 2015, 2016, 2017, 2018 and 2019, or all five years and in connection with the Restructuring Transactions described in Note 9. As a result, tax attributes such as net operating losses and research and development credits may be subject to further limitation. ASC 740 requires that the Company recognize the financial statement effects of a tax position when it is more likely than not, based on the technical merits, that the position will be sustained upon examination. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: Balance at December 31, 2017 $ 1,060 Additions based on tax positions related to prior year - Additions based on tax positions related to current year - Balance at December 31, 2018 1,060 Additions based on tax positions related to prior year - Additions based on tax positions related to current year - Balance at December 31, 2019 $ 1,060 There were no interest or penalties related to unrecognized tax benefits. Substantially all of the unrecognized tax benefit, if recognized to offset future taxable income would affect the Company’s tax rate. The Company does not anticipate that the amount of existing unrecognized tax benefits will significantly increase or decrease within the next 12 months. Because of net operating loss carryforwards, substantially all of the Company’s tax years remain open to federal tax and state tax examination. The Company files income tax returns in the U.S. federal jurisdiction, California and Florida. Federal and California corporation income tax returns beginning with the 2001 tax year remain subject to examination by the Internal Revenue Service and the California Franchise Tax Board, respectively.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Benefit Plan	11. Employee Benefit Plan The Company has established a 401(k) tax-deferred savings plan (the “401(k) Plan”), which permits participants to make contributions by salary deduction pursuant to Section 401(k) of the Internal Revenue Code. The Company is responsible for administrative costs of the 401(k) Plan. The Company may, at its discretion, make matching contributions to the 401(k) Plan. No employer contributions have been made to date.

Litigation

Litigation	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Litigation [Abstract]
Litigation	10. Litigation Savant Litigation On July 10, 2017, the Company filed a complaint against Savant in the Superior Court for the State of Delaware, New Castle County (the “Delaware Court”). KaloBios Pharmaceuticals, Inc. v. Savant Neglected Diseases, LLC On July 12, 2017, Savant removed the case to the Bankruptcy Court, claiming that the action is related to or arises under the Bankruptcy Case from which we emerged in July 2016. In re KaloBios Pharmaceuticals, Inc. On August 2, 2017, Savant sent a foreclosure notice to the Company, demanding that it provide the Collateral as defined in the Security Agreement for inspection and possession on August 9, 2017, with a public sale to be held on September 1, 2017. The Company moved for a Temporary Restraining Order (the “TRO”) and Preliminary Injunction in the Bankruptcy Court on August 4, 2017. Savant responded on August 7, 2017. On August 7, 2017, the Bankruptcy Court granted the Company’s motion for a TRO, entering an order prohibiting Savant from collecting on or selling the Collateral, entering our premises, issuing any default notices to us, or attempting to exercise any other remedies under the MDC Agreement or the Security Agreement. On August 9, 2017, the parties have stipulated to continue the provisions of the TRO in full force and effect until further order of the appropriate court, which the Bankruptcy Court signed that same day (the “Stipulated Order”). On January 22, 2018, Savant wrote to the Bankruptcy Court requesting dissolution of the TRO and the Stipulated Order. On January 29, 2018, the Bankruptcy Court granted the Motion to Remand and denied Savant’s request to dissolve the TRO and Stipulated Order, ordering that any request to dissolve the TRO and Stipulated Order be made to the Delaware Court. On February 13, 2018 Savant made a letter request to the Delaware Court to dissolve the TRO and Stipulated Order. Also on February 13, 2018, the Company filed its Answer and Affirmative defenses to Savant’s Counterclaims. On February 15, 2018 the Company filed a letter opposition to Savant’s request to dissolve the TRO and Stipulated Order and requesting a status conference. A hearing on Savant’s request to dissolve the TRO and Stipulated Order was held before the Delaware Court on March 19, 2018. The Delaware Court denied Savant’s request to dissolve the TRO and Stipulated order, which remain in effect. On April 11, 2018, the Company advised the Delaware Court that it would meet and confer with Savant regarding a proposed case management order and date for trial. On April 26, 2018 the Delaware Court so-ordered a proposed case management order submitted by the Company and Savant. The schedule in the case management order was modified by stipulation on August 24, 2018. On April 8, 2019, the Company moved to compel Savant to produce documents in response to the Company’s document requests. The parties thereafter agreed to a discovery schedule through June 30, 2019, which the Superior Court so-ordered, and the parties produced documents to each other. On June 4, 2019, Savant filed a complaint against the Company and Madison in the Delaware Court of Chancery (the “Chancery Action”) seeking to “recover as damages that amounts owed to it under the MDC Agreement, and to reclaim Savant’s intellectual property,” among other things. Savant also requested leave to move to dismiss the Company’s complaint on the grounds that the Company’s transfer of assets to Madison was champertous. On June 10, 2019, the Company requested by letter that the Superior Court hold a contempt hearing because the Chancery Action violated the TRO entered by the Bankruptcy Court, the terms of which have been extended by stipulation of the parties. On June 18, 2019, the Superior Court held a telephonic status conference. The parties agreed that the Chancery Action should be consolidated with the Superior Court action, after which the Superior Court would address the parties’ motions. On July 22, 2019, the Company moved for contempt against Savant. Savant filed its opposition on July 29, 2019. On August 12, 2019, the Superior Court denied the Company’s motion for contempt. On July 23, 2019, Savant moved for summary judgment on the issue of champerty. The Company filed its response and cross-motion for summary judgment on August 27, 2019. Savant filed its reply on September 10, 2019 and the Company filed its cross-reply on September 20, 2019. The motion is fully briefed, and was argued at a hearing on February 3, 2020. The court has not yet ruled on the motion. On July 26, 2019, the Company moved to modify the previously agreed-upon discovery schedule to extend discovery through December 31, 2019, which the Superior Court granted. In subsequent orders, the discovery schedule was further extended until the end of June 2020. On July 30, 2019, the Company filed a motion to dismiss Savant’s Chancery Action. Savant filed an amended complaint on September 4, 2019, and the Company filed its opening brief in support of its motion to dismiss on October 11, 2019. That motion is fully briefed and was argued at a hearing on February 3, 2020. The court has not yet ruled on the motion. On August 19, 2019, Savant moved to dismiss the Company’s amended Superior Court complaint. On September 27, 2019, the Company filed an opposition to Savant’s motion and, in the alternative, requested leave to file a second amended complaint against Savant. Savant consented to the filing of the second amended complaint and withdrew their motion to dismiss. Savant filed a partial motion to dismiss against a co-defendant on October 30, 2019. That motion is fully briefed and was argued at a hearing on February 3, 2020. At the February 3, 2020 hearing, the Court reserved judgment on the parties’ reciprocal motions. On November 18, 2019, the Court granted Savant’s Motion to Schedule a Preliminary Injunction hearing concerning the August 2017 TRO and Stipulated Order that are still in effect. At a hearing on April 28, 2020, the Court granted the application for a preliminary injunction to the Company, and the parties are preparing a proposed order to effectuate the Court’s rulings at the hearing. The Stipulated Order will no longer be in effect upon the entry of the preliminary injunction order. A trial is scheduled for October 2020.	12. Litigation Savant Litigation On July 10, 2017, the Company filed a complaint against Savant in the Superior Court for the State of Delaware, New Castle County (the “Delaware Court”). KaloBios Pharmaceuticals, Inc. v. Savant Neglected Diseases, LLC On July 12, 2017, Savant removed the case to the Bankruptcy Court, claiming that the action is related to or arises under the Bankruptcy Case from which we emerged in July 2016. In re KaloBios Pharmaceuticals, Inc. On August 2, 2017, Savant sent a foreclosure notice to the Company, demanding that it provide the Collateral as defined in the Security Agreement for inspection and possession on August 9, 2017, with a public sale to be held on September 1, 2017. The Company moved for a Temporary Restraining Order (the “TRO”) and Preliminary Injunction in the Bankruptcy Court on August 4, 2017. Savant responded on August 7, 2017. On August 7, 2017, the Bankruptcy Court granted the Company’s motion for a TRO, entering an order prohibiting Savant from collecting on or selling the Collateral, entering our premises, issuing any default notices to us, or attempting to exercise any other remedies under the MDC Agreement or the Security Agreement. On August 9, 2017, the parties have stipulated to continue the provisions of the TRO in full force and effect until further order of the appropriate court, which the Bankruptcy Court signed that same day (the “Stipulated Order”). On January 22, 2018, Savant wrote to the Bankruptcy Court requesting dissolution of the TRO and the Stipulated Order. On January 29, 2018, the Bankruptcy Court granted the Motion to Remand and denied Savant’s request to dissolve the TRO and Stipulated Order, ordering that any request to dissolve the TRO and Stipulated Order be made to the Delaware Court. On February 13, 2018 Savant made a letter request to the Delaware Court to dissolve the TRO and Stipulated Order. Also on February 13, 2018, the Company filed its Answer and Affirmative defenses to Savant’s Counterclaims. On February 15, 2018 the Company filed a letter opposition to Savant’s request to dissolve the TRO and Stipulated Order and requesting a status conference. A hearing on Savant’s request to dissolve the TRO and Stipulated Order was held before the Delaware Court on March 19, 2018. The Delaware Court denied Savant’s request to dissolve the TRO and Stipulated order, which remain in effect. On April 11, 2018, the Company advised the Delaware Court that it would meet and confer with Savant regarding a proposed case management order and date for trial. On April 26, 2018 the Delaware Court so-ordered a proposed case management order submitted by the Company and Savant. The schedule in the case management order was modified by stipulation on August 24, 2018. On April 8, 2019, the Company moved to compel Savant to produce documents in response to the Company’s document requests. The parties thereafter agreed to a discovery schedule through June 30, 2019, which the Superior Court so-ordered, and the parties produced documents to each other. On June 4, 2019, Savant filed a complaint against the Company and Madison in the Delaware Court of Chancery (the “Chancery Action”) seeking to “recover as damages that amounts owed to it under the MDC Agreement, and to reclaim Savant’s intellectual property,” among other things. Savant also requested leave to move to dismiss the Company’s complaint on the grounds that the Company’s transfer of assets to Madison was champertous. On June 10, 2019, the Company requested by letter that the Superior Court hold a contempt hearing because the Chancery Action violated the TRO entered by the Bankruptcy Court, the terms of which have been extended by stipulation of the parties. On June 18, 2019, the Superior Court held a telephonic status conference. The parties agreed that the Chancery Action should be consolidated with the Superior Court action, after which the Superior Court would address the parties’ motions. On July 22, 2019, the Company moved for contempt against Savant. Savant filed its opposition on July 29, 2019. On August 12, 2019, the Superior Court denied the Company’s motion for contempt. On July 23, 2019, Savant moved for summary judgment on the issue of champerty. The Company filed its response and cross-motion for summary judgment on August 27, 2019. Savant filed its reply on September 10, 2019 and the Company filed its cross-reply on September 20, 2019. The motion is fully briefed, and is scheduled for argument on February 3, 2020. On July 26, 2019, the Company moved to modify the previously agreed-upon discovery schedule to extend discovery through December 31, 2019, which the Superior Court granted. In a subsequent order, the discovery schedule was extended until the end of March 2020. On July 30, 2019, the Company filed a motion to dismiss Savant’s Chancery Action. Savant filed an amended complaint on September 4, 2019, and the Company filed its opening brief in support of its motion to dismiss on October 11, 2019. That motion is fully briefed and scheduled for argument on February 3, 2020. On August 19, 2019, Savant moved to dismiss the Company’s amended Superior Court complaint. On September 27, 2019, the Company filed an opposition to Savant’s motion and, in the alternative, requested leave to file a second amended complaint against Savant. Savant consented to the filing of the second amended complaint and withdrew their motion to dismiss. Savant filed a partial motion to dismiss against a co-defendant on October 30, 2019. That motion is fully briefed and is scheduled for argument on February 3, 2020. At the February 3, 2020 hearing, the Court reserved judgment on the parties’ reciprocal motions. On November 18, 2019, the Court granted Savant’s Motion to Schedule a Preliminary Injunction hearing concerning the August 2017 TRO and Stipulated Order that are still in effect. A briefing schedule has been set and the hearing is scheduled for March 25, 2020. The $2.0 million in milestone payments due Savant are included in Accrued expenses in the accompanying balance sheet as of December 31, 2019 and 2018. Recovery of the cost overages from Savant, if any, will be recorded in the period received.

License and Collaboration Agree

License and Collaboration Agreements	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
License and Collaboration Agreements	8. License and Collaboration Agreements Kite Agreement On May 30, 2019, the Company entered into a collaboration agreement (the “Kite Agreement”) with Kite Pharmaceuticals, Inc., pursuant to which the Company and Kite are conducting a multi-center Phase 1b/2 study of lenzilumab with Kite’s Yescarta in patients with relapsed or refractory B-cell lymphoma, including diffuse large B-cell lymphoma (“DLBCL”). The primary objective of the Study is to determine the effect of lenzilumab on the safety of Yescarta. Pursuant to the Kite Agreement, the Company shall supply lenzilumab to the collaboration for use in the study and will contribute up to approximately $8.0 million towards the out-of-pocket costs of the study, depending on the number of patients enrolled into the study. Mayo Agreement On June 19, 2019 the Company entered into an exclusive worldwide license agreement (the “Mayo Agreement”) with the Mayo Foundation for Medical Education and Research (“Mayo”) for certain technologies used to create CAR-T cells lacking GM-CSF expression through various gene-editing tools including CRISPR-Cas9 (GM-CSF knock-out). The license covers various patent applications and know-how developed by Mayo in collaboration with the Company. These licensed technologies complement and broaden the Company’s position in the GM-CSF neutralization space and expand the Company’s discovery platform aimed at improving CAR-T to include gene-edited CAR-T cells. Pursuant to the Mayo Agreement, the Company will pay $200,000 to Mayo within six months of the effective date, or upon completion of a qualified financing, whichever is earlier. The Mayo Agreement also requires the payment of milestones and royalties upon the achievement of certain regulatory and commercialization milestones. The Company accrued the initial payment and interest through March 31, 2020 in Accrued expenses in the accompanying Condensed Consolidated Balance Sheets as of December 31, 2019 and March 31, 2020. Zurich Agreement On July 19, 2019 the Company entered into an exclusive worldwide license agreement (the “Zurich Agreement”) with the University of Zurich (“UZH”) for technology used to prevent or treat Graft versus Host Disease (“GvHD”) through GM-CSF neutralization. The Zurich Agreement covers various patent applications filed by UZH which complement and broaden the Company’s position in the application of GM-CSF and expands the Company’s development platform to include improving allogeneic Hematopoietic Stem Cell Transplantation (“HSCT”). Pursuant to the Zurich Agreement, the Company paid $100,000 to UZH in July 2019. The Zurich Agreement also requires the payment of milestones and royalties upon the achievement of certain regulatory and commercialization milestones. The license payment of $100,000 was recorded as expense in Research and development in July 2019.	13. License and Collaboration Agreements Kite Agreement On May 30, 2019, the Company entered into the Kite Agreement, pursuant to which the Company and Kite will conduct a multi-center Phase Ib/II study of lenzilumab with Kite’s Yescarta in patients with relapsed or refractory B-cell lymphoma, including DLBCL. The primary objective of the Study is to determine the effect of lenzilumab on the safety of Yescarta. Pursuant to the Kite Agreement, the Company will supply lenzilumab to the collaboration for use in the study and will contribute up to approximately $8.0 million towards the out-of-pocket costs of the study. Mayo Agreement On June 19, 2019, the Company entered into an exclusive worldwide license agreement (the “Mayo Agreement”) with the Mayo Foundation for Medical Education and Research (“Mayo”) for certain technologies used to create CAR-T cells lacking GM-CSF expression through various gene-editing tools including CRISPR-Cas9 (“GM-CSF knock-out”). The license covers various patent applications and know-how developed by Mayo in collaboration with the Company. These licensed technologies complement and broaden the Company’s position in the GM-CSF neutralization space and expand the Company’s discovery platform aimed at improving CAR-T to include gene-edited CAR-T cells. Pursuant to the Mayo Agreement, the Company was required to pay $200,000 to Mayo within six months of the effective date, or upon completion of a qualified financing, whichever is earlier. The Company did not pay the initial payment as of the due date and will incur interest on the unpaid balance at the prime rate plus 2%. The Mayo Agreement also requires the payment of milestones and royalties upon the achievement of certain regulatory and commercialization milestones. The Company accrued the initial payment in Accrued expenses in the accompanying Consolidated Balance Sheet as of December 31, 2019. Zurich Agreement On July 19, 2019, the Company entered into an exclusive worldwide license agreement (the “Zurich Agreement”) with the University of Zurich (“UZH”) for technology used to prevent or treat Graft versus Host Disease (“GvHD”) through GM-CSF neutralization. The Zurich Agreement covers various patent applications filed by UZH which complement and broaden the Company’s position in the application of GM-CSF and expands the Company’s development platform to include improving allogeneic HSCT. Pursuant to the Zurich Agreement, the Company paid $100,000 to UZH in July 2019. The Zurich Agreement also requires the payment of milestones and royalties upon the achievement of certain regulatory and commercialization milestones. The license payment of $100,000 was recorded as expense in Research and development in the accompanying Consolidated Statements of Operations and Comprehensive Loss for the year ended December 31, 2019.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	14. Related Party Transactions The Restructuring Transactions were completed on February 27, 2018. See Note 9. In June, July and August, 2018 the Company received an aggregate of $0.9 million of proceeds from advance notes made to it by four different lenders including Dr. Cameron Durrant, our Chairman and Chief Executive Officer; Cheval, an affiliate of BHC, the Company’s controlling stockholder; and Ronald Barliant, a director of the Company. See Note 6 for a further discussion of the Advance Notes. Commencing September 19, 2018, the Company delivered a series of convertible promissory notes evidencing an aggregate of $2.5 million of loans made to the Company by six different lenders, including an affiliate of BHC, the Company’s controlling stockholder. See Note 6 for a further discussion of the 2018 Notes. On June 28, 2019, the Company issued three short-term, secured bridge notes evidencing an aggregate of $1.7 million of loans made to the Company by three parties including Dr. Cameron Durrant, our Chairman and Chief Executive Officer and Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., our controlling stockholder. See Note 6 for a further discussion of the 2019 Bridge Notes. On November 12, 2019, the Company issued two short-term, secured bridge notes (the “November Bridge Notes” and together with the June Bridge Notes, the “2019 Bridge Notes”) evidencing an aggregate of $350,000 of loans made to the Company by two parties, including Dr. Cameron Durrant, our Chairman and Chief Executive Officer and Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., our controlling stockholder. See Note 6 for a further discussion of the 2019 Bridge Notes.

Subsequent Events

Subsequent Events	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events Conversion of Outstanding 2018 and 2019 Convertible Notes As described in the Company’s 2019 Annual Report on Form 10-K, holders of the Company’s outstanding convertible notes issued in 2018 and 2019 are entitled to convert the principal and unpaid interest on such notes into shares of the Company’s common stock under various scenarios, including if the Company were to sell its equity securities on or before the date of repayment of the 2018 and 2019 Notes in any financing transaction that results in gross proceeds to the Company of less than $10 million (a “Non-Qualified Financing”). A Non-Qualified Financing occurred as a result of sales of our common stock to Lincoln Park Capital Fund, LLC starting on December 11, 2019 and concluding on January 7, 2020, pursuant to the Purchase Agreement described in Note 7, Stockholders’ Equity above. Commencing on April 2, 2020, the holders of such notes, including Cheval Holdings, Ltd. (“Cheval”), an affiliate of Black Horse Capital, L.P., our controlling stockholder, notified us of their exercise of such conversion rights. Pursuant to the exemption from registration afforded by Section 3(a)(9) under the Securities Act of 1933, we issued an aggregate of 11,989,578 shares of our common stock upon the conversion of $4.3 million in aggregate principal and interest on the notes converted, which obligations were retired. Of these, we issued 1,583,333 shares to Cheval. Dr. Dale Chappell, our ex-officio chief scientific officer, controls Black Horse Capital, L.P. and reports beneficial ownership of all shares held by it and its affiliates, including Cheval. After giving effect to the shares issued upon such conversions, as of May 14, 2020, no convertible notes issued in 2018 or 2019 were outstanding. April 2020 Bridge Notes On April 27, 2020, the Company issued two short-term, secured bridge notes (the “2020 Bridge Notes”) evidencing an aggregate of $350,000 of loans made to the Company by two parties: Cheval Holdings, Ltd., an affiliate of Black Horse Capital, L.P., the Company’s controlling stockholder, lent $100,000; and Nomis Bay LTD, the Company’s second largest stockholder, lent $250,000. The proceeds from the 2020 Bridge Notes were used for working capital and general corporate purposes. The 2020 Bridge Notes rank on par with the 2019 Bridge Notes, and possess other terms and conditions substantially consistent with those notes. The 2020 Bridge Notes bear interest at a rate of 7.0% per annum and have a maturity date of December 31, 2020. The 2020 Bridge Notes may become due and payable at such earlier time as the Company raises more than $10,000,000 in a bona fide financing transaction or upon a change in control. The 2020 Bridge Notes also are secured by a lien on substantially all of the Company’s assets. Upon an event of default, which events include, but are not limited to, (1) the Company’s failure to timely pay any monetary obligation under the 2020 Bridge Notes; (2) our failure to pay our debts generally as they become due and (3) our commencing any proceeding relating to the Company under any bankruptcy reorganization, arrangement, insolvency, readjustment of debt, dissolution or liquidation or similar laws of any jurisdiction now or hereafter in effect, the interest payable on the 2020 Bridge Notes increases to 10.0% per annum. Further, upon certain events of default, all payments and obligations due and owed under the 2020 Bridge Notes shall immediately become due and payable without demand and without notice to the Company. Paycheck Protection Plan Loan On May 5, 2020, the Company received a Paycheck Protection Plan loan under the 2020 CARES Act in the amount of $83 thousand (the “PPP Loan”), which the Company used for payroll costs. On June 26, 2020, the Company voluntarily repaid the PPP Loan in full, including applicable interest. 2020 Private Placement On June 1, 2020, the Company entered into a securities purchase agreement (the “Purchase Agreement”) with certain accredited investors to complete a private placement (the “Private Placement”) of common stock. The closing of the Private Placement occurred on June 2, 2020 (the “Closing Date”). At the closing, the Company issued and sold 82,528,718 shares of common stock at a purchase price of $0.87 per share, for aggregate gross proceeds of approximately $71.8 million. We used a portion of the proceeds to retire certain indebtedness, including all outstanding bridge notes. We expect to use the remaining proceeds from the Private Placement to retire other indebtedness, to fund our Phase III study of lenzilumab in COVID-19, our collaboration with Kite and other development programs, as well as for working capital and other general corporate purposes. Private Placement Litigation On June 15, 2020, a complaint was filed against Humanigen and Dr. Durrant in the Commercial Division of the Supreme Court of the State of New York. The plaintiffs comprise a group of 17 prospective investors introduced to Humanigen by Noble Capital Markets, Inc. (“Noble”), which had been engaged as a non-exclusive placement agent in connection with the Private Placement. The plaintiffs had indicated interest in purchasing shares of common stock in the Private Placement but, due to the strength of demand for shares from other prospective investors introduced to the company by J.P. Morgan Securities LLC, the lead placement agent for the Private Placement, the plaintiffs were not allocated any investment amount. The plaintiffs allege that the company and Dr. Durrant breached a contractual obligation to deliver shares of common stock to the plaintiffs. The plaintiffs seek to recover for losses due to alleged fraudulent misstatements and the company’s failure to deliver shares to them, and seek equitable relief in the form of specific performance. On June 19, 2020, Noble filed a separate complaint against Humanigen in the Circuit Court of the Fifteenth Judicial Circuit in and for Palm Beach County, Florida, also arising from the Private Placement. Noble’s complaint alleges that Humanigen breached the terms of its engagement letters with Noble by refusing to pay it the sales commissions it would have earned had its prospective investors received the entire allocation of shares sought in the Private Placement, as opposed to the $4 million of shares actually allocated to Noble and its clients. Noble is seeking payment in full of the commission, damages for Humanigen’s alleged tortious interference with Noble’s business relationship with the investors it introduced to Humanigen but which were not allocated shares in the Private Placement, and attorneys’ fees. Humanigen believes that the claims made in each complaint are without merit, and it is prepared to defend itself vigorously.	15. Subsequent Events Issuance of Convertible Notes in March 2020 In March 2020 (the “Issuance Date”), we delivered a series of convertible redeemable promissory notes (the “Notes”) evidencing loans with an aggregate principal amount of $448,333.33 made to us. The Notes bear interest at a rate of 7.0% per annum and will mature on March 13, 2021 and March 19, 2021, respectively. The Notes contain an original issue discount of $33,000 and $18,833.33, respectively. We plan to use the proceeds from the Notes for working capital. Beginning on the 6th month anniversary of the Issuance Date, unless earlier redeemed by us, the holder is entitled, at its option, to convert all or any amount of the principal amount of the Notes then outstanding, together with the accrued and unpaid interest on such portion of the Notes proposed to be converted, into shares of our common stock (the "Common Stock") at a conversion price equal to $.25 per share (the “Fixed Price”). After the 9 month anniversary of the Issuance Date, the conversion price shall be equal to the lower of (i) the Fixed Price or (ii) 68% of the lowest of either the trading price or closing bid of the Common Stock, for the ten prior trading days including the day upon which a Notice of Conversion is received (the “Variable Conversion Price”). In the event our Common Stock has a closing price equal to $0.30 or less for 5 consecutive days prior to the 9 month anniversary of the Issuance Date, then, beginning on the 6 month anniversary of the Issuance Date, the holder may elect in its Notice of Conversion to use the lower of the Fixed Price or the Variable Conversion Price set forth above. Commencing on the 6 month anniversary of the Issuance Date, we will have the right, but not the obligation, to elect to make fixed monthly amortizing payments to the holder in the amount of $25,000. If we elect to make such payments, the holder shall not be entitled to convert all or any amount of the principal amount of the Notes then outstanding if and for so long as we are current in respect of the amortizing payments. The Notes may be redeemed by us at any time before the 270 th The Notes contain customary default and remedies provisions for convertible note financings of this nature. The Notes were issued in reliance upon the exemption from registration afforded by Section 4(a)(2) of the Securities Act of 1933, as amended. Conversion of Certain Outstanding 2018 and 2019 Convertible Notes As previously reported, holders of the Company’s outstanding convertible notes issued in 2018 and 2019 are entitled to convert the principal and unpaid interest on such notes into shares of our common stock as a result of our completion on December 11, 2019 of a “Non-Qualified Financing”, as defined in such notes, through sales of our common stock to Lincoln Park Capital Fund, LLC pursuant to the Purchase Agreement described in Note 9 in the Notes to the Consolidated Financial Statements. Certain additional “Non-Qualified Financing” transactions occurred from December 11, 2019 until January 7, 2020. Commencing on April 2, 2020, certain holders of such notes, including Cheval Holdings, Ltd. (“Cheval”), an affiliate of Black Horse Capital, L.P., our controlling stockholder, notified us of their exercise of such conversion rights. Pursuant to the exemption from registration afforded by Section 3(a)(9) under the Securities Act of 1933, we issued an aggregate of 7,131,942 shares of our common stock upon the conversion of $2.6 million in aggregate principal and interest on the notes converted, which obligations were retired. Of these, we issued 1,583,333 shares to Cheval. Dr. Dale Chappell, our ex-officio chief scientific officer, controls Black Horse Capital, L.P. and reports beneficial ownership of all shares held by it and its affiliates, including Cheval. After giving effect to the shares issued upon such conversions, as of April 3, 2020, an aggregate of $0.6 million in principal amount of convertible notes issued in 2018, and an aggregate of $1.2 million in principal amount of convertible notes issued in 2019 were outstanding.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Use of Estimates		Basis of Presentation and Use of Estimates The accompanying Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and include all adjustments necessary for the presentation of the Company’s consolidated financial position, results of operations and cash flows for the periods presented. The Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries. These financial statements have been prepared on a basis that assumes that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the Consolidated Financial Statements and accompanying notes. Actual results could differ materially from those estimates. The Company believes judgment is involved in accounting for the fair value-based measurement of stock-based compensation, accruals, convertible notes and warrants. The Company evaluates its estimates and assumptions as facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ from these estimates and assumptions, and those differences could be material to the Consolidated Financial Statements.
Concentration of Credit Risk		Concentration of Credit Risk Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk in the event of a default by the related financial institution holding the securities, to the extent of the value recorded in the balance sheet. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments with lower credit risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk.
Fair Value of Financial Instruments		Fair Value of Financial Instruments The fair value of financial instruments reflects the amounts that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The fair value hierarchy is based on three levels of inputs that may be used to measure fair value, of which the first two are considered observable, and the third is considered unobservable, as follows: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than those included in Level 1 that are directly or indirectly observable, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company measures the fair value of financial assets and liabilities using the highest level of inputs that are reasonably available as of the measurement date. The following tables summarize the fair value of financial assets (marketable securities) that are measured at fair value, and the classification by level of input within the fair value hierarchy: Fair Value Measurements as of December 31, 2019 Level 1 Level 2 Level 3 Total Investments: Money market funds $ 71 $ — $ — $ 71 Total assets measured at fair value $ 71 $ — — $ 71 Fair Value Measurements as of December 31, 2018 Level 1 Level 2 Level 3 Total Investments: Money market funds $ 71 $ — $ — $ 71 Total assets measured at fair value $ 71 $ — — $ 71 The estimated fair value of the Advance notes, Notes payable to vendors, Bridge notes and Convertible notes as of December 31, 2019 and 2018, based upon current market rates for similar borrowings, as measured using Level 3 inputs, approximate the carrying amounts as presented in the Consolidated Balance Sheets.
Cash and Cash Equivalents		Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of deposits with commercial banks in checking, interest-bearing and demand money market accounts.
Restricted Cash		Restricted Cash Restricted cash at December 31, 2019 of $0.07 million related to a standby letters of credit in the amount of $0.05 million issued in connection with certain insurance policy coverage maintained by the Company and restricted cash related to a credit card facility in the amount of $0.02 million. Restricted cash at December 31, 2018 of $0.07 million related to a standby letters of credit in the amount of $0.05 million issued in connection with certain insurance policy coverage maintained by the Company and restricted cash related to a credit card facility in the amount of $0.02 million.
Debt Issue Costs		Debt Issue Costs Debt issuance costs related to a recognized debt liability are presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts and are amortized to interest expense over the term of the related debt on the effective interest method.
Research and Development Expenses		Research and Development Expenses Development costs incurred in the research and development of new product candidates are expensed as incurred, including expenses that may or may not be reimbursed under research and development collaboration arrangements. Research and development costs include, but are not limited to, salaries, benefits, stock-based compensation, laboratory supplies, allocated overhead, fees for professional service providers and costs associated with product development efforts, including preclinical studies and clinical trials. The Company estimates preclinical study and clinical trial expenses based on the services performed, pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered. The Company records upfront and milestone payments made to third parties under licensing arrangements as an expense. Upfront payments are recorded when incurred and milestone payments are recorded when the specific milestone has been achieved.
Research and Development Services		Research and Development Services Internal and external research and development costs incurred in connection with collaboration agreements are recognized as revenue in the same period as the costs are incurred and are presented on a gross basis when the Company acts as a principal, has the discretion to choose suppliers, bears credit risk, and performs at least part of the services.
Revenue Recognition		Revenue Recognition The Company’s revenue to date has been generated primarily through license agreements and research and development collaboration agreements. The Company had no revenues for the years ending December 31, 2019 and 2018. Commencing January 1, 2018, the Company recognizes revenue in accordance with ASC 606. The core principle of ASC 606 is that an entity should recognize revenue to depict the transfer of promised goods and/or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and/or services. To determine the appropriate amount of revenue to be recognized for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following steps: (i) identify the contract(s) with the customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) each performance obligation is satisfied. Revenue under technology licenses and collaborative agreements typically consists of nonrefundable and/or guaranteed license fees, collaborative research funding, and various milestone and future product royalty or profit-sharing payments. These agreements are generally referred to as “multiple element arrangements”. The Company applies the accounting standard on revenue recognition for multiple element arrangements. The fair value of deliverables under the arrangement may be derived using a best estimate of selling price if vendor specific objective evidence and third-party evidence is not available. Deliverables under the arrangement will be separate units of accounting if a delivered item has value to the customer on a standalone basis and if the arrangement includes a general right of return for the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the Company’s control. The Company recognizes upfront license payments as revenue upon delivery of the license only if the license has standalone value from any undelivered performance obligations and that value can be determined. The undelivered performance obligations typically include manufacturing or development services or research and/or steering committee services. If the fair value of the undelivered performance obligations can be determined, then these obligations would be accounted for separately. If the license is not considered to have standalone value, then the license and other undelivered performance obligations would be accounted for as a single unit of accounting. In this case, the license payments and payments for performance obligations are recognized as revenue over the estimated period of when the performance obligations are performed or deferred indefinitely until the undelivered performance obligation is determined. Whenever the Company determines that an arrangement should be accounted for as a single unit of accounting, the Company determines the period over which the performance obligations will be performed, and revenue will be recognized. Revenue is recognized using a proportional performance or straight-line method. The proportional performance method is used when the level of effort required to complete performance obligations under an arrangement can be reasonably estimated. The amount of revenue recognized under the proportional performance method is determined by multiplying the total payments under the contract, excluding royalties and payments contingent upon achievement of milestones, by the ratio of the level of effort performed to date to the estimated total level of effort required to complete performance obligations under the arrangement. If the Company cannot reasonably estimate the level of effort to complete performance obligations under an arrangement, the Company recognizes revenue under the arrangement on a straight-line basis over the period the Company is expected to complete its performance obligations. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete its performance obligations under an arrangement. The Company’s collaboration agreements typically entitle the Company to additional payments upon the achievement of development, regulatory and sales performance-based milestones. If the achievement of a milestone is considered probable at the inception of the collaboration, the related milestone payment is included with other collaboration consideration, such as upfront fees and research funding, in the Company’s revenue calculation. Typically, these milestones are not considered probable at the inception of the collaboration. As such, milestones will typically be recognized in one of two ways depending on the timing of when the milestone is achieved. If the milestone is achieved during the performance period, then the Company will only recognize revenue to the extent of the proportional performance achieved at that date, or the proportion of the straight-line basis achieved at that date, and the remainder will be recorded as deferred revenue to be amortized over the remaining performance period. If the milestone is achieved after the performance period has completed and all performance obligations have been delivered, then the Company will recognize the milestone payment as Revenue in its entirety in the period the milestone was achieved.
Leases		Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. The FASB subsequently issued ASU No. 2018-10 and 2018-11 in July 2018, which provide clarifications and improvements to ASU 2016-02 (collectively, the “new lease standard”). ASU No. 2018-11 provides the optional transition method which allows companies to apply the new lease standard at the adoption date instead of at the earliest comparative period presented and continue to apply the provisions of the previous lease standard in its annual disclosures for the comparative periods. The new lease standard requires lessees to present a right-of-use asset and a corresponding lease liability on the balance sheet. Additional footnote disclosures related to leases is also required. On January 1, 2019, the Company adopted the new lease standard using the optional transition method and certain other practical expedients. Under the practical expedient package elected, the Company is not required to reassess whether expired or existing contracts are or contain a lease; and is not required to reassess the lease classifications or reassess the initial direct costs associated with expired or existing leases. The new lease standard also provides practical expedients for an entity’s ongoing accounting. The Company elected the short-term lease recognition exemption for all leases that qualify. This means, for those leases that qualify, we will not recognize right of use assets or lease liabilities, and this includes not recognizing right of use assets or lease liabilities for existing short-term leases of those assets in transition. The Company elected the practical expedient to not separate lease and non-lease components for certain classes of assets. The Company sub-leases office-space under a short-term lease for $300 per month. Management has determined the lease term to be less than 12 months, including renewals, and therefore has not recorded a right-of-use asset and corresponding liability under the short-term lease recognition exemption. Lease costs for the years ended December 31, 2019 and 2018 totaled approximately $10,700 and $204,800, respectively and are included in the Consolidated Statements of Operations and Comprehensive Loss. Because the Company has elected to adopt the transitional practical expedients, Management was not required to reassess whether any existing or expired contracts contained embedded leases. The Company has not entered into any contracts during the 2019 fiscal year that contain an embedded lease.
Stock-Based Compensation Expense		Stock-Based Compensation Expense The Company measures stock-based compensation expense for stock awards at the grant date, based on the fair value-based measurement of the award, and the expense is recorded over the related service period, generally the vesting period, net of estimated forfeitures. The Company calculates the fair value-based measurement of stock options using the Black-Scholes valuation model and the single-option method and recognizes expense using the straight-line attribution approach.
Income Taxes		Income Taxes The Company accounts for income taxes under an asset-and-liability approach. Deferred income taxes reflect the impact of temporary differences between assets and liabilities recognized for tax and financial reporting purposes measured by applying enacted tax rates and laws that will be in effect when the differences are expected to reverse, net operating loss carryforwards and tax credits. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company’s policy is to include interest and penalties related to unrecognized tax benefits within the Company’s provision for income taxes.
Comprehensive Loss		Comprehensive Loss Comprehensive loss represents net loss adjusted for the change during the periods presented in unrealized gains and losses on available-for-sale securities less reclassification adjustments for realized gains or losses included in net loss. The unrealized gains or losses are reported on the Consolidated Statements of Operations and Comprehensive Loss.
Net Loss Per Common Share		Net Loss Per Common Share Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, stock options, restricted stock units and common stock warrants are considered to be potentially dilutive securities but are excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods presented. The Company’s potential dilutive securities, which include stock options, restricted stock units and warrants have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per common share and be antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in all periods presented. The following shares subject to outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share as the effect of including such securities would be antidilutive: Year Ended December 31, 2019 2018 Options to purchase common stock 15,881,721 15,409,357 Warrants to purchase common stock 331,193 331,193 16,212,914 15,740,550
Segment Reporting		Segment Reporting The Company determines its segment reporting based upon the way the business is organized for making operating decisions and assessing performance. The Company operates in only one segment, which is related to the development of pharmaceutical products.
Recent Accounting Pronouncements		Recent Accounting Pronouncements Until December 31, 2018, the Company qualified as an “emerging growth company” (“EGC”) pursuant to the provisions of the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”) and elected to take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act which permits EGCs to defer compliance with new or revised accounting standards until non-issuers are required to comply with such standards. A registrant with EGC status loses its eligibility as an EGC five years after its common equity initial public offering, or December 31, 2018 for the Company. Accordingly, the Company was required to adopt new accounting standards on the same timeline as other public companies effective January 1, 2018. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash”. ASU 2016-18 requires the inclusion of restricted cash with cash and cash equivalents when reconciling the beginning-of-the period and end-of-period total amounts shown on the statement of cash flows. The Company adopted the standard effective January 1, 2018. As a result of the adoption, the Company will no longer present the change within restricted cash in the consolidated statements of cash flows. See below for the composition of cash, cash equivalents and restricted cash shown on the statements of cash flow: Year Ended December 31, 2019 2018 Cash and cash equivalents $ 143 $ 814 Restricted cash 71 71 Total cash, cash equivalents and restricted cash as shown on statement of $ 214 $ 885 In June 2018, the FASB issued ASU 2018-07, “Compensation – Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting”. This ASU expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees and is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted. The Company adopted the standard effective January 1, 2019. The adoption of this standard did not have a material impact on the Company’s Consolidated Financial Statements and related disclosures. In November 2018, the FASB issued ASU No. 2018-18, “Collaborative Arrangements (Topic 808)—Clarifying the Interaction between Topic 808 and Topic 606”. ASU 2018-18 makes targeted improvements for collaborative arrangements by clarifying that certain transactions between collaborative arrangement participants should be accounted for as revenue under Topic 606 when the collaborative arrangement participant is a customer in the context of a unit of account. In those situations, all the guidance in Topic 606 should be applied, including recognition, measurement, presentation, and disclosure requirements. In addition, unit-of-account guidance in Topic 808 was aligned with the guidance in Topic 606 (that is, a distinct good or service) when an entity is assessing whether the collaborative arrangement or a part of the arrangement is within the scope of Topic 606. ASU 2018-18 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. The amendments in this Update should be applied retrospectively to the date of initial application of Topic 606. The Company is currently evaluating the requirements of ASU 2018-18 and has not yet determined its impact on the Company’s Consolidated Financial Statements and related disclosures.
Derivative Financial Instruments	Derivative Financial Instruments The Company has equity conversion features within its 2020 Convertible Redeemable Notes that qualify as embedded derivatives under the guidance of FASB ASC Topic 815, Derivatives and Hedging

Chapter 11 Filing (Tables)

Chapter 11 Filing (Tables)	12 Months Ended
	Dec. 31, 2019
Chapter 11Filing Tables Abstract
Schedule of Reorganization Items, Net	For the years ended December 31, 2019 and 2018, Reorganization items, net consisted of the following charges: Year Ended December 31, 2019 2018 Legal fees $ - $ 119 Professional fees - 26 Total reorganization items, net $ - $ 145

Potentially Dilutive Securiti_2

Potentially Dilutive Securities (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Potentially Dilutive Securities Tables
Potentially Dilutive Securities Excluded From Computation of Diluted Net Loss Per Common Share	The following outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share: As of March 31, 2020 2019 Options to purchase common stock 17,104,649 16,062,922 Warrants to purchase common stock 331,193 331,193 17,435,842 16,394,115	The following shares subject to outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share as the effect of including such securities would be antidilutive: Year Ended December 31, 2019 2018 Options to purchase common stock 15,881,721 15,409,357 Warrants to purchase common stock 331,193 331,193 16,212,914 15,740,550

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Schedule of fair value of financial assets and liabilities measured at fair value and classification by level of input		The following tables summarize the fair value of financial assets (marketable securities) that are measured at fair value, and the classification by level of input within the fair value hierarchy: Fair Value Measurements as of December 31, 2019 Level 1 Level 2 Level 3 Total Investments: Money market funds $ 71 $ — $ — $ 71 Total assets measured at fair value $ 71 $ — — $ 71 Fair Value Measurements as of December 31, 2018 Level 1 Level 2 Level 3 Total Investments: Money market funds $ 71 $ — $ — $ 71 Total assets measured at fair value $ 71 $ — — $ 71
Schedule of antidilutive securities excluded from computations of diluted net loss per common share	The following outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share: As of March 31, 2020 2019 Options to purchase common stock 17,104,649 16,062,922 Warrants to purchase common stock 331,193 331,193 17,435,842 16,394,115	The following shares subject to outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share as the effect of including such securities would be antidilutive: Year Ended December 31, 2019 2018 Options to purchase common stock 15,881,721 15,409,357 Warrants to purchase common stock 331,193 331,193 16,212,914 15,740,550
Schedule of composition of cash, cash equivalents and restricted cash		See below for the composition of cash, cash equivalents and restricted cash shown on the statements of cash flow: Year Ended December 31, 2019 2018 Cash and cash equivalents $ 143 $ 814 Restricted cash 71 71 Total cash, cash equivalents and restricted cash as shown on statement of $ 214 $ 885

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Schedule of amortized cost and fair value of investments, with gross unrealized gains and losses	At December 31, 2019, the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows: Gross Gross Amortized Unrealized Unrealized Cost Gains Losses Fair Value Money market funds $ 71 $ — $ — $ 71 Total investments $ 71 $ — $ — $ 71 Reported as: Cash and cash equivalents $ — Restricted cash 71 Total investments $ 71 At December 31, 2018 the amortized cost and fair value of investments, with gross unrealized gains and losses, were as follows: Gross Gross Amortized Unrealized Unrealized Cost Gains Losses Fair Value Money market funds $ 71 $ — $ — $ 71 Total investments $ 71 $ — $ — $ 71 Reported as: Cash and cash equivalents $ - Restricted cash, long-term 71 Total investments $ 71

Debt (Tables)

Debt (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Disclosure Text Block [Abstract]
Schedule of Maturities of Debt	As of March 31, 2020, the maturities of the debt of the Company by year is as follows: Total 2020 2021 Principal payments on Notes payable to vendors $ 774 $ 774 $ - Interest payments on Notes payable to vendors 348 348 - Principal payments on 2019 Bridge notes 2,050 2,050 - Interest payments on 2019 Bridge notes 99 99 - Principal payments on Convertible notes 4,293 3,018 1,275 Interest payments on Convertible notes 358 270 88 Gross debt before unamortized discount 7,922 6,559 1,363 Unamortized debt discount on convertible debt (607 ) (532 ) (75 ) Total Debt $ 7,315 $ 6,027 $ 1,288	As of December 31, 2019, the maturities of the debt of the Company by year is as follows: Total 2020 2021 Principal payments on Notes payable to vendors $ 774 $ 774 $ - Interest payments on Notes payable to vendors 320 320 - Principal payments on 2019 Bridge notes 2,050 2,050 - Interest payments on 2019 Bridge notes 63 63 - Principal payments on Convertible notes 3,775 2,500 1,275 Interest payments on Convertible notes 290 224 66 Gross debt before unamortized discount 7,272 5,931 1,341 Unamortized debt discount on convertible debt (785 ) (691 ) (94 ) Total Debt $ 6,487 $ 5,240 $ 1,247

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Schedule of shares of common stock reserved for issuance		The Company has reserved the following shares of common stock for issuance as of December 31, 2019: Warrants to purchase common stock 331,193 Options: Outstanding under the 2012 Equity Incentive Plan 15,881,406 Outstanding under the 2001 Equity Incentive Plan 315 Available for future grants under the 2012 Equity Incentive Plan 3,050,799 Shares reserved under the 2019 LPC Purchase Agreement 14,500,000 Total common stock reserved for future issuance 33,763,713
Summary of stock option activity	A summary of stock option activity for the three months ended March 31, 2020 under all of the Company’s options plans is as follows: Options Weighted Outstanding at January 1, 2020 15,881,721 $ 0.95 Granted 1,223,033 0.40 Exercised - - Cancelled (forfeited) - - Cancelled (expired) (105 ) 11.68 Outstanding at March 31, 2020 17,104,649 $ 0.91	The following table summarizes stock option activity for the years ended December 31, 2019 and 2018: Number of Weighted Weighted- Aggregate Outstanding at January 1, 2018 2,448,383 $ 4.15 Granted 13,575,038 0.66 Cancelled (forfeited) (572,935 ) 3.20 Cancelled (expired) (41,129 ) 37.82 Outstanding at December 31, 2018 15,409,357 0.95 Granted 1,470,957 0.78 Exercised (488,625 ) 0.67 Cancelled (forfeited) (509,923 ) 0.62 Cancelled (expired) (45 ) 9.68 Outstanding at December 31, 2019 15,881,721 $ 0.95 8.2 $ 49 Options vested and expected to vest 15,827,723 $ 0.95 8.2 $ 49 Exercisable 13,661,670 $ 0.99 8.0 $ 22 (1) The weighted average price per share is determined using exercise price per share for stock options. (2) The aggregate intrinsic value is calculated as the difference between the exercise price of the option and the fair value of the Company’s common stock for in-the-money options at December 31, 2019.
Schedule of stock options outstanding and exercisable by exercise price		The stock options outstanding and exercisable by exercise price at December 31, 2019 are as follows: Stock Options Outstanding Stock Options Exercisable Range of Exercise Prices Number of Weighted- Weighted- Number of Weighted- $0.33 - $0.67 13,442,367 8.28 $ 0.65 11,533,358 $ 0.66 $0.84 - $1.30 755,080 9.15 $ 1.09 445,705 $ 0.94 $1.91 - $3.30 370,000 7.10 $ 2.97 368,333 $ 2.97 $3.38 - $3.38 1,263,022 6.71 $ 3.38 1,263,022 $ 3.38 $3.40 - $4.72 50,625 6.77 $ 3.40 50,625 $ 3.40 $8.24 - $17.36 315 1.02 $ 12.94 315 $ 12.94 $42.88 - $48.00 312 3.76 $ 45.17 312 $ 45.17 15,881,721 8.17 $ 0.95 13,661,670 $ 0.99
Schedule of fair value-based measurement of stock options granted under the entity's stock plans estimated using Black-Scholes model	The Company valued the options granted using the Black-Scholes options pricing model and the following weighted-average assumption terms for the three months ended : Three months ended March 31, 2020 Exercise price $0.38 - $0.40 Market value $0.38 - $0.40 Expected term 5 years Expected volatility 95% Risk-free interest rate 1.47% - 1.57% Expected dividend yield 0%	The fair value- based measurement of stock options granted under the Company’s stock plans was estimated at the date of grant using the Black-Scholes model with the following assumptions: Year Ended December 31, 2019 2018 Expected term 5 - 6 years 5 - 6 years Expected volatility 96% - 99% 93% - 97% Risk-free interest rate 1.74% - 2.59% 2.7% - 2.8% Expected dividend yield 0% 0%
Schedule of total stock-based compensation expense recognized	The Company recorded stock-based compensation expense in the Condensed Consolidated Statements of Operations as follows: Three months ended March 31, 2020 2019 General and administrative $ 211 $ 697 Research and development 54 - Total stock-based compensation $ 265 $ 697	Total expense for stock option grants recognized was as follows: Year ended December 31, 2019 2018 General and administrative $ 1,928 $ 4,611 Research and development 97 201 Total stock-based compensation $ 2,025 $ 4,812

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of significant components of deferred tax assets	Significant components of the Company's deferred tax assets are as follows: As of December 31, 2019 2018 Deferred tax assets: Net operating losses $ 50,144 $ 47,877 Research and other credits 2,178 2,178 Stock based compensation 3,001 2,682 In-Process research and development 1,253 1,314 Other 854 708 Total deferred tax assets 57,430 54,759 Valuation allowance (57,430 ) (54,759 ) Net deferred tax assets $ - $ -
Schedule of reconciliation of the statutory tax rates and the effective tax rates	A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 2019 and 2018 is as follows: Year Ended December 31, 2019 2018 Statutory rate 21.0 % 21.0 % Valuation allowance (26.0 )% (26.4 )% Nondeductible stock compensation (0.3 )% 0.1 % Other 5.3 % 5.3 % Effective tax rate - % - %

Nature of Operations (Details)

Nature of Operations (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)item	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 287,362	$ 284,895	$ 274,601
Number of product candidates approved for sale | item	0
Total liabilities	$ 16,721	14,841	$ 9,480
Working capital deficit	$ 15,100	$ 13,100

Organization and Description _2

Organization and Description of Business (Details) $ in Thousands	Nov. 12, 2019USD ($)	Jun. 04, 2018USD ($)	Mar. 12, 2018USD ($)	Jan. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jun. 28, 2019USD ($)	Apr. 23, 2019USD ($)	Mar. 31, 2020USD ($)item	May 31, 2019USD ($)	Mar. 31, 2019USD ($)	Aug. 31, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Accumulated deficit					$ 284,895			$ 287,362				$ 284,895	$ 274,601
Number of product candidates approved for sale | item								0
Total liabilities					14,841			$ 16,721				14,841	9,480
Working capital deficit					13,100			15,100				13,100
Proceeds from issuance of exercise of stock options												325
Proceeds from issuance of common stock		$ 200	$ 1,100	$ 100	200			$ 65				185	2,781
Proceeds from advance notes											$ 900	$ 2,050	$ 925
Percentage of high concentration in patients												20.00%
Lincoln Park Capital Purchase Agreement [Member]
Proceeds from issuance of common stock				$ 300	$ 186
2019 Convertible Notes Payable [Member]
Proceeds from advance notes							$ 1,300
June Bridge Notes [Member]
Proceeds from advance notes						$ 1,700
Bridge Loan [Member]
Proceeds from advance notes	$ 350
Chairman and Chief Executive Officer and two other members of our Board of Directors [Member]
Proceeds from issuance of exercise of stock options									$ 324

Chapter 11 Filing (Narrative) (

Chapter 11 Filing (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jul. 11, 2018
Cash payment for reorganization items	$ 0	$ 200
Subject To Review By Bankruptcy Court [Member]
Disallowed bankruptcy claims, amount			$ 500

Chapter 11 Filing (Reorganizati

Chapter 11 Filing (Reorganization Items, Net) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Chapter 11 Filing Reorganization Items Net
Legal fees		$ 119
Professional fees		26
Total reorganization items, net		$ 145

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Accounting Policies [Abstract]
Restricted cash current, standby letters of credit	$ 70,000	$ 70,000
Issuance of letters of credit for insurance policy coverage	50,000	50,000
Restricted cash related credit card facility	$ 20,000	20,000
Number of operating segments	1
Short-term lease amount per month	$ 300
Lease costs	$ 10,700	$ 204,800

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Fair Value of Financial Instruments) (Details) - Fair Value Measurements Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Estimate Of Fair Value Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value	$ 71	$ 71
Estimate Of Fair Value Fair Value Disclosure [Member] | Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value	71	71
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value	71	71
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value	71	71
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets measured at fair value

Summary of Significant Accoun_6

Summary of Significant Accounting Policies (Potentially Dilutive Securities) (Details) - shares	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	17,435,842	16,394,115	16,212,914	15,740,550
Warrants to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	331,193	331,193	331,193	331,193
Options to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	17,104,649	16,062,922	15,881,721	15,409,357

Summary of Significant Accoun_7

Summary of Significant Accounting Policies (composition of cash, cash equivalents and restricted cash) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 68	$ 143	$ 814
Restricted cash	$ 71	71	71
Total cash, cash equivalents and restricted cash as shown on statement of cash flows		$ 214	$ 885

Potentially Dilutive Securiti_3

Potentially Dilutive Securities (Details) - shares	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	17,435,842	16,394,115	16,212,914	15,740,550
Options to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	17,104,649	16,062,922	15,881,721	15,409,357
Warrants to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	331,193	331,193	331,193	331,193

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 71	$ 71
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	71	71
Cash And Cash Equivalents [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value
Restricted Cash [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value	71	71
Money Market Funds [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	71	71
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	$ 71	$ 71

Savant Arrangements (Details)

Savant Arrangements (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 10, 2017	May 26, 2017	Jun. 30, 2016	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2019	Jun. 30, 2017
Number of shares called by warrant						331,193	331,193
Research and development	$ 1,000	$ 1,000		$ 659	$ 359	$ 2,616	$ 2,219
Aggregate cost overages								$ 4,100	$ 3,400
Net of duductible									500
Due to Savant				$ 2,000		$ 2,000	$ 2,000	$ 2,100	2,000
Savant Neglected Diseases, LLC [Member]
Number of shares called by warrant			200,000	100,000
Exercise price of warrant			$ 2.25	$ 2.25
Exercise period of warrant			5 years
Due from Savant									$ 1,400
Savant Neglected Diseases, LLC [Member] | Exercisable Immediately [Member]
Percentage of warrants exercisable			25.00%

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($)

Nov. 12, 2019

Jul. 02, 2019

Dec. 30, 2019

May 30, 2019

Apr. 23, 2019

Sep. 19, 2018

Mar. 31, 2020

Mar. 31, 2019

Aug. 31, 2018

Jun. 28, 2019

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2020

Jun. 30, 2016

Debt Instrument [Line Items]

Debt instrument amount

$ 5,000,000

Proceeds from advance notes

$ 900,000

$ 2,050,000

$ 925,000

Percentage of accrued interest

7.00%

Common stock conversion price

$ 0.45

$ 0.45

Intrinsic value of this beneficial conversion feature

143,000

1,465,000

Proceeds from convertible debt

$ 467,000

1,275,000

2,500,000

Issuance of common stock upon note conversions shares

2,179,622

Interest expense

410,000

302,000

1,349,000

852,000

Non Qualified Financing [Member]

Debt Instrument [Line Items]

Proceeds from convertible debt

10,000,000

Advance Notes [Member]

Debt Instrument [Line Items]

Proceeds from advance notes

1,700,000

$ 1,700,000

2019 Bridge Notes [Member]

Debt Instrument [Line Items]

Interest rate

10.00%

10.00%

Accrued interest

$ 100,000

$ 100,000

Term loan interest rate

7.00%

7.00%

Debt instrument amount

$ 1,700,000

Proceeds from advance notes

$ 750,000

Interest expense debt

$ 100,000

Maturity Date

Oct. 1, 2019

Oct. 1, 2019

2019 Bridge Notes [Member] | Bona fide financing [Member]

Debt Instrument [Line Items]

Proceeds from advance notes

$ 3,000,000

2019 Bridge Notes [Member] | November Bridge Notes [Member]

Debt Instrument [Line Items]

Interest rate

7.00%

Debt instrument amount

$ 350,000

Proceeds from advance notes

$ 3,000,000

Maturity Date

Dec. 31, 2019

Mar. 31, 2020

Dec. 31, 2020

2019 Bridge Notes [Member] | November Bridge Notes [Member] | Cheval Holdings [Member]

Debt Instrument [Line Items]

Debt instrument amount

$ 250,000

2019 Bridge Notes [Member] | November Bridge Notes [Member] | Cameron Durrant [Member]

Debt Instrument [Line Items]

Debt instrument amount

$ 100,000

2019 Bridge Notes [Member] | Advance Notes [Member]

Debt Instrument [Line Items]

Proceeds from advance notes

950,000

2019 Bridge Notes [Member] | Nomis Bay LTD [Member]

Debt Instrument [Line Items]

Debt instrument amount

750,000

2019 Bridge Notes [Member] | Cameron Durrant [Member]

Debt Instrument [Line Items]

Debt instrument amount

750,000

2019 Bridge Notes [Member] | Chief Executive Officer [Member]

Debt Instrument [Line Items]

Debt instrument amount

$ 200,000

2019 Bridge Notes [Member] | Bona Fide Financing Transaction [Member]

Debt Instrument [Line Items]

Proceeds from advance notes

$ 3,000,000

3,000,000

Black Horse Capital LP [Member] | Convertible Promissory Note [Member]

Debt Instrument [Line Items]

Term loan interest rate

7.00%

Debt instrument amount

$ 2,500,000

2018 Convertible Notes Payable [Member] | Convertible Promissory Note [Member]

Debt Instrument [Line Items]

Accrued interest

$ 300,000

200,000

2018 Convertible Notes Payable [Member] | Qualified Financing [Member]

Debt Instrument [Line Items]

Proceeds from convertible debt

$ 10,000,000

Conversion price

$ 0.45

2018 Convertible Notes Payable [Member] | Non Qualified Financing [Member]

Debt Instrument [Line Items]

Proceeds from convertible debt

$ 10,000,000

Conversion price

$ 0.45

2018 Convertible Notes Payable [Member] | Advance Notes [Member]

Debt Instrument [Line Items]

Common stock conversion price

$ 0.45

$ 0.45

Intrinsic value of this beneficial conversion feature

$ 1,800,000

$ 1,900,000

Debt discount amortization

$ 200,000

800,000

800,000

Interest expense debt

$ 300,000

100,000

Remaining Discount Amortization Period

9 months

2019 Convertible Notes Payable [Member]

Debt Instrument [Line Items]

Term loan interest rate

7.50%

7.50%

Debt instrument amount

$ 1,300,000

Proceeds from advance notes

$ 1,300,000

2019 Convertible Notes Payable [Member] | Convertible Promissory Note [Member]

Debt Instrument [Line Items]

Accrued interest

$ 100,000

$ 100,000

2019 Convertible Notes Payable [Member] | Qualified Financing [Member]

Debt Instrument [Line Items]

Proceeds from convertible debt

$ 10,000,000

Conversion price

$ 1.25

2019 Convertible Notes Payable [Member] | Non Qualified Financing [Member]

Debt Instrument [Line Items]

Proceeds from convertible debt

$ 10,000,000

Conversion price

$ 1.25

2019 Convertible Notes Payable [Member] | Advance Notes [Member]

Debt Instrument [Line Items]

Common stock conversion price

$ 1.25

$ 1.25

Intrinsic value of this beneficial conversion feature

$ 1,800,000

$ 1,900,000

Debt discount amortization

300,000

300,000

Interest expense debt

$ 300,000

100,000

Remaining Discount Amortization Period

16 months

2020 Convertible Redeemable Notes [Member]

Debt Instrument [Line Items]

Interest rate

7.00%

Accrued interest

$ 1,600

Common stock conversion price

$ 0.25

Proceeds from convertible debt

$ 518,333

Percentage of conversion price

68.00%

Common stock closing price

$ 0.30

Interest expense

$ 4,000

Fair value of convertible notes

0

2020 Convertible Redeemable Notes [Member] | One Convertible Redeemable Promissory notes [Member]

Debt Instrument [Line Items]

Debt discount amortization

$ 33,000

Maturity Date

Mar. 13, 2021

Amount of Fixed monthly amortizing payments

$ 25,000

2020 Convertible Redeemable Notes [Member] | Two Convertible Redeemable Promissory notes [Member]

Debt Instrument [Line Items]

Debt discount amortization

$ 18,833

Maturity Date

Mar. 19, 2021

Amount of Fixed monthly amortizing payments

$ 14,250

2020 Convertible Notes Payable [Member] | Advance Notes [Member]

Debt Instrument [Line Items]

Remaining Discount Amortization Period

11 months

Notes Payable To Vendors [Member]

Debt Instrument [Line Items]

Interest rate

10.00%

Notes payable to vendors

$ 1,200,000

Accrued interest

$ 300,000

$ 300,000

$ 300,000

Notes Payable To Vendors [Member] | 2019 Bridge Notes [Member]

Debt Instrument [Line Items]

Accrued interest

$ 1,100,000

$ 1,100,000

Debt instrument amount

$ 500,000

Debt (Schedule of Maturities of

Debt (Schedule of Maturities of Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total	$ 7,315	$ 6,487
2020	6,027	5,240
2021	1,288	1,247
Principal payments on Notes payable to vendors [Member]
Debt Instrument [Line Items]
Total	774	774
2020	774	774
2021
Interest payments on Notes payable to vendors [Member]
Debt Instrument [Line Items]
Total	348	320
2020	348	320
2021
Principal payments on 2019 Bridge notes [Member]
Debt Instrument [Line Items]
Total	2,050	2,050
2020	2,050	2,050
2021
Interest payments on 2019 Bridge notes [Member]
Debt Instrument [Line Items]
Total	99	63
2020	99	63
2021
Principal payments on Convertible notes [Member]
Debt Instrument [Line Items]
Total	4,293	3,775
2020	3,018	2,500
2021	1,275	1,275
Interest payments on Convertible notes [Member]
Debt Instrument [Line Items]
Total	358	290
2020	270	224
2021	88	66
Gross debt before unamortized discount [Member]
Debt Instrument [Line Items]
Total	7,922	7,272
2020	6,559	5,931
2021	1,363	1,341
Unamortized debt discount on convertible debt [Member]
Debt Instrument [Line Items]
Total	607	785
2020	532	691
2021	$ 75	$ 94

Warrants to Purchase Common S_2

Warrants to Purchase Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 04, 2015	Jun. 19, 2013
Class of Warrant or Right [Line Items]
Issuance of warrant to purchase shares of common stock			331,193	331,193
Reduction of expense warrant		$ 100
Warrant [Member]
Class of Warrant or Right [Line Items]
Issuance of warrant to purchase shares of common stock					125,000	6,193
Exercise price of warrants issued (in dollars per share)					$ 29.32	$ 96.88
Options vested			100,000
Options not vested			100,000
Savant Warrant [Member]
Class of Warrant or Right [Line Items]
Issuance of warrant to purchase shares of common stock	200,000
Exercise price of warrants issued (in dollars per share)	$ 2.25
Warrants initial fair value	$ 700
Term of issuance of warrant	5 years
Percentage of warrant exercisable	25.00%

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Other Commitments [Line Items]
Rent expense	$ 10	$ 200
Brisbane, California Lease [Member]
Other Commitments [Line Items]
Expiration date	Sep. 30, 2018
Burlingame, California Lease [Member]
Other Commitments [Line Items]
Expiration date	Mar. 31, 2020

Stockholders' Equity (Narrative

Stockholders' Equity (Narrative) (Details) - USD ($)	Jun. 04, 2018	Mar. 12, 2018	Jan. 31, 2020	Dec. 31, 2019	Feb. 27, 2018	Dec. 22, 2017	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Nov. 08, 2019	Feb. 28, 2018	Dec. 21, 2017
Class of Stock [Line Items]
Common Stock, shares authorized upon the completion of the IPO				225,000,000			225,000,000		225,000,000	225,000,000
Stock issued			200,000	500,000					500,000
Common stock, par value				$ 0.001			$ 0.001		$ 0.001	$ 0.001
Common share issued	400,000	2,445,557		114,034,451			114,311,790		114,034,451	109,897,526
Total proceeds	$ 200,000	$ 1,100,000	$ 100,000	$ 200,000			$ 65,000		$ 185,000	$ 2,781,000
Equity Incentive Plan Twenty Twelve [Member]
Class of Stock [Line Items]
Vesting period expiration							10 years		10 years
Equity Incentive Plan Twenty Twelve [Member] | Minimum [Member]
Class of Stock [Line Items]
Vesting period							3 years		3 years
Equity Incentive Plan Twenty Twelve [Member] | Maximum [Member]
Class of Stock [Line Items]
Vesting period							4 years		4 years
Lincoln Park Capital Purchase Agreement [Member]
Class of Stock [Line Items]
Stock issued			700,000
Common stock, par value											$ 0.001
Value of right to sell number of shares											$ 20,000,000
Right to sell number of shares											100,000
Threshold prices but not to exceed in total proceeds											$ 750,000
Percentage of beneficially owning more than common stock outstanding											4.99%
Common share issued											706,592
Total proceeds			$ 300,000	$ 186,000
Common Stock [Member]
Class of Stock [Line Items]
Common Stock, shares authorized upon the completion of the IPO												225,000,000
Preferred Stock [Member]
Class of Stock [Line Items]
Common Stock, shares authorized upon the completion of the IPO												25,000,000
Nomis Bay [Member]
Class of Stock [Line Items]
Term loan					$ 18,400,000								$ 3,000,000
Percentage owned					70.00%
Claims advances					$ 100,000
Accrued interest and fees					8,500,000
Legal fees and expenses					300,000
Common stock held					$ 33,573,530
Percentage of outstanding common stock					31.40%
New Lender Shares [Member]
Class of Stock [Line Items]
Stock issued					59,786,848
Madison [Member]
Class of Stock [Line Items]
Percentage owned					30.00%
New Black Horse Shares [Member]
Class of Stock [Line Items]
Term loan					$ 9,900,000
Stock issued					32,028,669
Total consideration					$ 3,000,000
Common stock held					$ 66,870,851
Percentage of outstanding common stock					62.60%
Bridge Loan [Member]
Class of Stock [Line Items]
Total consideration						$ 1,500,000

Stockholders' Equity (Schedule

Stockholders' Equity (Schedule of Shares of Common Stock Reserved for Issuance) (Details) - USD ($)	Mar. 09, 2018	Sep. 13, 2016	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants to purchase common stock				331,193	331,193
Total common stock reserved for future issuance				33,763,713
Total fair value of options vested				$ 2,000,000	$ 4,800,000
Weighted-average fair value of options granted during the period				$ 0.79	$ 0.47
Weighted-average period			1 year 7 months 6 days	1 year 4 months 24 days
Unrecognized compensation expense			$ 700,000	$ 1,000,000
2019 LPC Purchase Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total common stock reserved for future issuance				14,500,000
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding				15,881,406
Available for future grants	7,500,000	3,000,000		3,050,799
Vesting period expiration			10 years	10 years
Number of shares authorized to be issued under the plan	16,050,000
2012 Equity Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total common stock reserved for future issuance		125,000				1,100,000
Vesting period			4 years	4 years
2012 Equity Incentive Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years	3 years
2001 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option outstanding				315
2001 Stock Option Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to be issued under the plan				426,030

Stockholders' Equity (Stock Opt

Stockholders' Equity (Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Number of Shares
Balance at the beginning of the period (in shares)		15,881,721	15,409,357		2,448,383
Options granted (in shares)		1,223,033	1,470,957		13,575,038
Options exercised (in shares)			(488,625)
Options cancelled (forfeited) (in shares)			(509,923)		(572,935)
Options cancelled (expired) (in shares)		(105)	(45)		(41,129)
Balance at the end of the period (in shares)		17,104,649	15,881,721		15,409,357
Options vested and expected to vest at the end of the period (in shares)			15,827,723
Options exercisable (in shares)			13,661,670
Weighted-Average Exercise Price (per share)
Balance at the beginning of the period (in dollars per share)	[1]	$ 0.95	$ 0.95		$ 4.15
Options granted (in dollars per share)		0.40	0.78	[1]	0.66	[1]
Options exercised (in dollars per share)			0.67	[1]
Options cancelled (forfeited) (in dollars per share)			0.62	[1]	3.20	[1]
Options cancelled (expired) (in dollars per share)		11.68	9.68	[1]	37.82	[1]
Balance at the ending of the period (in dollars per share)		$ 0.91	0.95	[1]	$ 0.95	[1]
Options vested and expected to vest at the end of the period (in dollars per share)	[1]		0.95
Options exercisable (in dollars per share)	[1]		$ 0.99
Weighted-Average Remaining Contractual Term (in years)
Balance at the end of the period			8 years 2 months 12 days
Options vested and expected to vest at the end of the period			8 years 2 months 12 days
Options exercisable			8 years
Aggregate Intrinsic Value (in thousands)
Balance at the end of the period	[2]		$ 49
Options vested and expected to vest at the end of the period	[2]		49
Options exercisable	[2]		$ 22
[1]	The weighted average price per share is determined using exercise price per share for stock options.
[2]	The aggregate intrinsic value is calculated as the difference between the exercise price of the option and the fair value of the Company's common stock for in-the-money options at December 31, 2019.

Stockholders' Equity (Options O

Stockholders' Equity (Options Outstanding and Exercisable By Price Range) (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Stock Options Outstanding
Number of Shares | shares	15,881,721
Weighted Average Remaining Contractual Life	8 years 2 months 1 day
Weighted Average Exercise Price (in dollars per share)	$ 0.95
Stock Options Exercisable
Number of Shares | shares	13,661,670
Weighted Average Exercise Price Per Share (in dollars per share)	$ 0.99
Exercise Price Range From $0.33 - $0.67 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price, low end of range (in dollars per share)	0.33
Exercise Price, high end of range (in dollars per share)	$ 0.67
Stock Options Outstanding
Number of Shares | shares	13,442,367
Weighted Average Remaining Contractual Life	8 years 3 months 11 days
Weighted Average Exercise Price (in dollars per share)	$ 0.65
Stock Options Exercisable
Number of Shares | shares	11,533,358
Weighted Average Exercise Price Per Share (in dollars per share)	$ 0.66
Exercise Price Range From $0.84 - $0.1.30 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price, low end of range (in dollars per share)	0.84
Exercise Price, high end of range (in dollars per share)	$ 1.30
Stock Options Outstanding
Number of Shares | shares	755,080
Weighted Average Remaining Contractual Life	9 years 1 month 24 days
Weighted Average Exercise Price (in dollars per share)	$ 1.09
Stock Options Exercisable
Number of Shares | shares	445,705
Weighted Average Exercise Price Per Share (in dollars per share)	$ 0.94
Exercise Price Range From $1.91 To $3.30 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price, low end of range (in dollars per share)	1.91
Exercise Price, high end of range (in dollars per share)	$ 3.30
Stock Options Outstanding
Number of Shares | shares	370,000
Weighted Average Remaining Contractual Life	7 years 1 month 6 days
Weighted Average Exercise Price (in dollars per share)	$ 2.97
Stock Options Exercisable
Number of Shares | shares	368,333
Weighted Average Exercise Price Per Share (in dollars per share)	$ 2.97
Exercise Price Range From $3.38 To $3.38 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price, low end of range (in dollars per share)	3.38
Exercise Price, high end of range (in dollars per share)	$ 3.38
Stock Options Outstanding
Number of Shares | shares	1,263,022
Weighted Average Remaining Contractual Life	6 years 8 months 16 days
Weighted Average Exercise Price (in dollars per share)	$ 3.38
Stock Options Exercisable
Number of Shares | shares	1,263,022
Weighted Average Exercise Price Per Share (in dollars per share)	$ 3.38
Exercise Price Range From $3.40 To $4.72 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price, low end of range (in dollars per share)	3.40
Exercise Price, high end of range (in dollars per share)	$ 4.72
Stock Options Outstanding
Number of Shares | shares	50,625
Weighted Average Remaining Contractual Life	6 years 9 months 7 days
Weighted Average Exercise Price (in dollars per share)	$ 3.40
Stock Options Exercisable
Number of Shares | shares	50,625
Weighted Average Exercise Price Per Share (in dollars per share)	$ 3.40
Exercise Price Range From $8.24 To $17.36 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price, low end of range (in dollars per share)	8.24
Exercise Price, high end of range (in dollars per share)	$ 17.36
Stock Options Outstanding
Number of Shares | shares	315
Weighted Average Remaining Contractual Life	1 year 7 days
Weighted Average Exercise Price (in dollars per share)	$ 12.94
Stock Options Exercisable
Number of Shares | shares	315
Weighted Average Exercise Price Per Share (in dollars per share)	$ 12.94
Exercise Price Range From $42.88 To $48.00 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise Price, low end of range (in dollars per share)	42.88
Exercise Price, high end of range (in dollars per share)	$ 48
Stock Options Outstanding
Number of Shares | shares	312
Weighted Average Remaining Contractual Life	3 years 9 months 3 days
Weighted Average Exercise Price (in dollars per share)	$ 45.17
Stock Options Exercisable
Number of Shares | shares	312
Weighted Average Exercise Price Per Share (in dollars per share)	$ 45.17

Stockholders' Equity (Fair Valu

Stockholders' Equity (Fair Value Assumptions) (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Expected term	5 years
Expected volatility	95.00%
Expected volatility, minimum (as a percent)		96.00%	93.00%
Expected volatility, maximum (as a percent)		99.00%	97.00%
Risk-free interest rate, minimum (as a percent)	1.47%	1.74%	2.70%
Risk-free interest rate, maximum (as a percent)	1.57%	2.59%	2.80%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Minimum [Member]
Expected term		5 years	5 years
Exercise price	$ 0.38
Market value	0.38
Maximum [Member]
Expected term		6 years	6 years
Exercise price	0.40
Market value	$ 0.40

Stockholders' Equity (Stock-Bas

Stockholders' Equity (Stock-Based Compensation Expense Recognized) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 265,000	$ 697,000	$ 2,025,000	$ 4,812,000
Unrecognized compensation expense	$ 700,000		$ 1,000,000
Weighted average period for recognition	1 year 7 months 6 days		1 year 4 months 24 days
General And Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 211,000	697,000	$ 1,928,000	4,611,000
Research And Development Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 54,000		$ 97,000	$ 201,000

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Increase (decrease) in valuation allowance	$ 2.7	$ 3.2
Internal Revenue Service I R S [Member]
Net operating loss carryforwards	166.2	$ 15.4
Internal Revenue Service I R S [Member] | Research [Member]
Tax credit carryforwards	$ 1.3
Internal Revenue Service I R S [Member] | Minimum [Member]
Expiration year	Dec. 31, 2021
Internal Revenue Service I R S [Member] | Minimum [Member] | Research [Member]
Expiration year	Dec. 31, 2022
Internal Revenue Service I R S [Member] | Maximum [Member]
Expiration year	Dec. 31, 2037
Internal Revenue Service I R S [Member] | Maximum [Member] | Research [Member]
Expiration year	Dec. 31, 2035
State And Local Jurisdiction [Member]
Net operating loss carryforwards	$ 172
State And Local Jurisdiction [Member] | Research [Member]
Tax credit carryforwards	$ 2.2
State And Local Jurisdiction [Member] | Minimum [Member]
Expiration year	Dec. 31, 2028
State And Local Jurisdiction [Member] | Maximum [Member]
Expiration year	Dec. 31, 2039

Income Taxes (Significant Compo

Income Taxes (Significant Components of Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating losses	$ 50,144	$ 47,877
Research and other credits	2,178	2,178
Stock based compensation	3,001	2,682
In-Process research and development	1,253	1,314
Other	854	708
Total deferred tax assets	57,430	54,759
Valuation allowance	(57,430)	(54,759)
Net deferred tax assets

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of the Statutory Tax Rates and Effective Tax Rates) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the statutory tax rates and the effective tax rates
Statutory rate	21.00%	21.00%
Valuation allowance	(26.00%)	(26.40%)
Nondeductible stock compensation	(0.30%)	0.10%
Other	5.30%	5.30%
Effective tax rate

Income Taxes (Reconciliation _2

Income Taxes (Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at the beginning of the period	$ 1,060	$ 1,060
Additions based on tax positions related to prior year
Additions based on tax positions related to current year
Balance at the end of the period	$ 1,060	$ 1,060

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Retirement Benefits [Abstract]
Employer contributions	$ 0

Litigation (Details)

Litigation (Details) - Savant [Member] - USD ($) $ in Thousands	1 Months Ended
	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018
Aggregate cost	$ 3,400
Deductible	500
Offset payment due	2,000
Amount owed	$ 1,400
Accrued expenses		$ 2,000	$ 2,000

License and Collaboration Agr_2

License and Collaboration Agreements (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Jul. 19, 2019	May 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Mayo Agreement [Member]
Amount paid in license agreement			$ 200	$ 200
Interest rate				2.00%
Kite Agreement [Member]
Amount paid in license agreement		$ 8,000
Zurich Agreement [Member]
Amount paid in license agreement	$ 100
Zurich Agreement [Member] | Research And Development Expense [Member]
Amount paid in license agreement			$ 100	$ 100

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	3 Months Ended	12 Months Ended
	Aug. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Nov. 12, 2019	Jun. 28, 2019	Sep. 19, 2018
Proceeds from advance notes	$ 900,000	$ 2,050,000	$ 925,000
Debt instrument amount	$ 5,000,000
Convertible Promissory Note [Member] | Black Horse Capital LP [Member]
Debt instrument amount						$ 2,500,000
Issued three short-term, secured bridge notes [Member]
Short term debt					$ 1,700,000
Issued two short-term, secured bridge notes [Member]
Short term debt				$ 350,000

Subsequent Events (Details)

Subsequent Events (Details)

Jun. 02, 2020USD ($)$ / sharesshares

Apr. 03, 2020USD ($)

Apr. 02, 2020USD ($)shares

Mar. 13, 2020USD ($)$ / shares

Jun. 15, 2020

Apr. 27, 2020USD ($)

Mar. 31, 2020USD ($)shares

Mar. 30, 2020USD ($)

Mar. 19, 2020USD ($)

May 30, 2019shares

Mar. 31, 2020USD ($)

Mar. 31, 2019USD ($)

Aug. 31, 2018USD ($)

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Jun. 19, 2020USD ($)

May 05, 2020USD ($)

Subsequent Event [Line Items]

Proceeds from convertible debt

$ 467,000

$ 1,275,000

$ 2,500,000

Issuance of common stock upon note conversions shares | shares

2,179,622

Debt instrument amount

$ 5,000,000

Proceeds from advance notes

$ 900,000

$ 2,050,000

$ 925,000

Non Qualified Financing [Member]

Subsequent Event [Line Items]

Proceeds from convertible debt

$ 10,000,000

Subsequent Event [Member]

Subsequent Event [Line Items]

Number of prospective investor

17

Shares sought in private placement

$ 4,000,000

Subsequent Event [Member] | 2020 Private Placement [Member]

Subsequent Event [Line Items]

Issuance and sold common stock | shares

82,528,718

Purchase Price per share | $ / shares

$ 0.87

Aggregate gross Proceeds

$ 71,800,000

Subsequent Event [Member] | 2020 Bridge Notes [Member]

Subsequent Event [Line Items]

Interest rate

7.00%

Debt instrument amount

$ 350,000

Maturity Date

Dec. 31, 2020

Subsequent Event [Member] | 2020 CARES Act [Member]

Subsequent Event [Line Items]

Amount received under paycheck Protection Plan loan

$ 83,000

Subsequent Event [Member] | 2018 convertible notes [Member]

Subsequent Event [Line Items]

Proceeds from convertible debt

$ 600,000

Subsequent Event [Member] | 2019 convertible notes [Member]

Subsequent Event [Line Items]

Proceeds from convertible debt

$ 1,200,000

Subsequent Event [Member] | Cheval Holdings [Member] | 2020 Bridge Notes [Member]

Subsequent Event [Line Items]

Debt instrument amount

$ 100,000

Subsequent Event [Member] | Nomis Bay LTD [Member] | 2020 Bridge Notes [Member]

Subsequent Event [Line Items]

Debt instrument amount

$ 250,000

Subsequent Event [Member] | Convertible Promissory Note [Member]

Subsequent Event [Line Items]

Proceeds from convertible debt

$ 4,300,000

$ 2,600,000

Issuance of common stock upon note conversions shares | shares

11,989,578

7,131,942

Subsequent Event [Member] | Convertible Promissory Note [Member] | Cheval Holdings [Member]

Subsequent Event [Line Items]

Issuance of common stock upon note conversions shares | shares

1,583,333

1,583,333

Subsequent Event [Member] | Bona Fide Financing Transaction [Member] | 2020 Bridge Notes [Member]

Subsequent Event [Line Items]

Interest rate

10.00%

Proceeds from advance notes

$ 10,000,000

Subsequent Event [Member] | Convertible redeemable promissory note [Member]

Subsequent Event [Line Items]

Proceeds from convertible debt

$ 448,333.33

Interest rate

7.00%

7.00%

Maturity Date

Mar. 13, 2021

Mar. 19, 2021

Debt discount

$ 33,000

$ 18,833.33

Common stock conversion price | $ / shares

$ 0.25

Percentage of conversion price

68.00%

Common stock closing price | $ / shares

$ 0.30

Amount of Fixed monthly amortizing payments

$ 25,000