Humanigen (HGENQ) 10-Q 12 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 09, 2021
Cover [Abstract]
Entity Central Index Key	0001293310
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Entity File Number	001-35798
Entity Registrant Name	Humanigen, Inc
Entity Incorporation State or Country Code	DE
Entity Tax Identification Number	77-0557236
Entity Address, Address Line One	533 Airport Boulevard
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Burlingame
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94010
City Area Code	650
Local Phone Number	243-3100
Title of 12(b) Security	Common Stock
Trading Symbol	HGEN
Name of Exchange on which Security is Registered	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Bankruptcy Proceedings, Reporting Current	true
Entity Common Stock, Shares Outstanding		63,818,233

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 76,500	$ 67,737
Prepaid expenses and other current assets	1,347	475
Total current assets	77,847	68,212
Other assets	90	90
Total assets	77,937	68,302
Current liabilities:
Accounts payable	45,962	15,366
Accrued expenses	18,602	3,175
Deferred revenue	4,145	1,874
Total current liabilities	68,709	20,415
Non-current liabilities:
Deferred revenue	2,054	2,342
Long-term debt	24,818
Total liabilities	95,581	22,757
Stockholders' equity (deficit):
Common stock, $0.001 par value: 225,000,000 shares authorized at September 30, 2021 and December 31, 2020; 60,017,333 and 51,626,508 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	60	52
Additional paid-in capital	559,835	419,923
Accumulated deficit	(577,539)	(374,430)
Total stockholders' equity (deficit)	(17,644)	45,545
Total liabilities and stockholders' equity (deficit)	$ 77,937	$ 68,302

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	60,017,333	51,626,508
Common stock, shares outstanding	60,017,333	51,626,508

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Total revenue	$ 1,036		$ 2,558
Operating expenses:
Research and development	60,811	22,416	183,757	44,218
General and administrative	6,204	8,331	19,228	11,685
Total operating expenses	67,015	30,747	202,985	55,903
Loss from operations	(65,979)	(30,747)	(200,427)	(55,903)
Other expense:
Interest expense	(751)	(3)	(1,516)	(1,336)
Other expense, net	(9)	(1)	(1,166)	(1)
Net loss	$ (66,739)	$ (30,751)	$ (203,109)	$ (57,240)
Basic and diluted net loss per common share	$ (1.12)	$ (0.71)	$ (3.56)	$ (1.79)
Weighted average common shares outstanding used to calculate basic and diluted net loss per common share	59,486,626	43,490,071	56,997,039	32,041,790
License [Member]
Revenue:
Total revenue	$ 1,036		$ 2,558

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Operating activities:
Net loss	$ (66,739)	$ (65,567)	$ (30,751)	$ (2,467)	$ (203,109)	$ (57,240)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock based compensation expense					3,815	1,634
Non-cash interest expense related to debt financing					374	706
Issuance of common stock for payment of compensation						78
Issuance of common stock in exchange for services						212
Changes in operating assets and liabilities:
Prepaid expenses and other assets					(872)	(309)
Accounts payable					30,596	3,697
Accrued expenses					15,427	5,065
Deferred revenue					1,983
Net cash used in operating activities					(151,786)	(46,157)
Investing activities:
Purchase of intangible assets						(20)
Net cash used in investing activities						(20)
Financing activities:
Net proceeds from issuance of common stock					134,140	139,760
Proceeds from exercise of stock options					1,965	572
Net proceeds from issuance of long-term debt					24,444	10
Net proceeds from issuance of convertible notes						467
Net proceeds from issuance of PPP loan						83
Net proceeds from issuance of bridge notes						350
Payments on PPP loan						(83)
Payments on bridge notes						(2,400)
Payments on convertible notes						(518)
Payments on notes payable to vendors						(776)
Net cash provided by financing activities					160,549	137,465
Net increase in cash and cash equivalents					8,763	91,288
Cash and cash equivalents, beginning of period		$ 67,737		143	67,737	143	$ 143
Cash and cash equivalents, end of period	$ 76,500		91,431		76,500	91,431	$ 67,737
Supplemental cash flow disclosure:
Cash paid for interest					961	671
Supplemental disclosure of non-cash investing and financing activities:
Issuance of stock options in lieu of cash compensation						180
Issuance of warrants for services			$ 1,948	$ 1		2,066
Conversion of notes payable and related accrued interest and fees to common stock						$ 4,316

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Total
Balances at Dec. 31, 2019	$ 22	$ 270,555	$ (284,895)	$ (14,318)
Balances (in shares) at Dec. 31, 2019	22,806,890
Issuance of common stock, net of expenses		65		65
Issuance of common stock, net of expenses, shares	40,000
Issuance of common stock in exchange for services		13		13
Issuance of common stock in exchange for services, shares	5,868
Issuance of stock options for payment of compensation		133		133
Issuance of common stock for payment of compensation		19		19
Issuance of common stock for payment of compensation, shares	9,599
Issuance of warrant for services		1		1
Stock-based compensation expense		265		265
Net loss			(2,467)	(2,467)
Balances at Mar. 31, 2020	$ 22	271,051	(287,362)	(16,289)
Balances (in shares) at Mar. 31, 2020	22,862,357
Balances at Dec. 31, 2019	$ 22	270,555	(284,895)	(14,318)
Balances (in shares) at Dec. 31, 2019	22,806,890
Issuance of warrant for services				2,066
Net loss				(57,240)
Balances at Sep. 30, 2020	$ 52	419,353	(342,135)	77,270
Balances (in shares) at Sep. 30, 2020	51,616,508
Balances at Mar. 31, 2020	$ 22	271,051	(287,362)	(16,289)
Balances (in shares) at Mar. 31, 2020	22,862,357
Issuance of common stock, net of expenses	$ 17	66,987		67,004
Issuance of common stock, net of expenses, shares	16,505,744
Issuance of common stock for conversion of debt	$ 3	4,313		4,316
Issuance of common stock for conversion of debt, shares	2,397,916
Issuance of common stock in exchange for services		57		57
Issuance of common stock in exchange for services, shares	15,463
Issuance of stock options for payment of compensation		32		32
Issuance of common stock for payment of compensation		29		29
Issuance of common stock for payment of compensation, shares	4,915
Issuance of warrant for services		117		117
Issuance of common stock upon option exercise
Issuance of common stock upon option exercise, shares	188,521
Stock-based compensation expense		357		357
Net loss			(24,022)	(24,022)
Balances at Jun. 30, 2020	$ 42	342,943	(311,384)	31,601
Balances (in shares) at Jun. 30, 2020	41,974,916
Issuance of common stock, net of expenses	$ 10	72,681		72,691
Issuance of common stock, net of expenses, shares	9,200,000
Issuance of common stock in exchange for services		142		142
Issuance of common stock in exchange for services, shares	13,733
Issuance of stock options for payment of compensation		15		15
Issuance of common stock for payment of compensation		30		30
Issuance of common stock for payment of compensation, shares	2,803
Issuance of warrant for services		1,948		1,948
Issuance of common stock upon option exercise		572		572
Issuance of common stock upon option exercise, shares	202,147
Issuance of common stock upon warrant exercise		10		10
Issuance of common stock upon warrant exercise, shares	222,909
Stock-based compensation expense		1,012		1,012
Net loss			(30,751)	(30,751)
Balances at Sep. 30, 2020	$ 52	419,353	(342,135)	77,270
Balances (in shares) at Sep. 30, 2020	51,616,508
Balances at Dec. 31, 2020	$ 52	419,923	(374,430)	45,545
Balances (in shares) at Dec. 31, 2020	51,626,508
Issuance of common stock, net of expenses	$ 2	36,104		36,106
Issuance of common stock, net of expenses, shares	1,796,858
Issuance of common stock upon option exercise		429		429
Issuance of common stock upon option exercise, shares	233,323
Stock-based compensation expense		510		510
Net loss			(65,567)	(65,567)
Balances at Mar. 31, 2021	$ 54	456,966	(439,997)	17,023
Balances (in shares) at Mar. 31, 2021	53,656,689
Balances at Dec. 31, 2020	$ 52	419,923	(374,430)	45,545
Balances (in shares) at Dec. 31, 2020	51,626,508
Issuance of warrant for services
Net loss				(203,109)
Balances at Sep. 30, 2021	$ 60	559,835	(577,539)	(17,644)
Balances (in shares) at Sep. 30, 2021	60,017,333
Balances at Mar. 31, 2021	$ 54	456,966	(439,997)	17,023
Balances (in shares) at Mar. 31, 2021	53,656,689
Issuance of common stock, net of expenses	$ 5	94,167		94,172
Issuance of common stock, net of expenses, shares	5,427,017
Issuance of common stock upon option exercise		1,432		1,432
Issuance of common stock upon option exercise, shares	319,153
Stock-based compensation expense		1,871		1,871
Net loss			(70,803)	(70,803)
Balances at Jun. 30, 2021	$ 59	554,436	(510,800)	43,695
Balances (in shares) at Jun. 30, 2021	59,402,859
Issuance of common stock, net of expenses	$ 1	3,861		3,862
Issuance of common stock, net of expenses, shares	600,933
Issuance of common stock upon option exercise		104		104
Issuance of common stock upon option exercise, shares	13,541
Stock-based compensation expense		1,434		1,434
Net loss			(66,739)	(66,739)
Balances at Sep. 30, 2021	$ 60	$ 559,835	$ (577,539)	$ (17,644)
Balances (in shares) at Sep. 30, 2021	60,017,333

Nature of Operations

Nature of Operations	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Description of the Business Humanigen, Inc. (the “Company”) was incorporated on March 15, 2000 in California, reincorporated as a Delaware corporation in September 2001 as KaloBios Pharmaceuticals, Inc., and in August 2017, the Company changed its name to Humanigen, Inc. The Company is a clinical stage biopharmaceutical company, developing its portfolio of anti-inflammatory immunology and immuno-oncology monoclonal antibodies. The Company is focusing its efforts on the development of its lead product candidate, lenzilumab, its proprietary Humaneered® anti-human granulocyte-macrophage colony-stimulating factor (“GM-CSF”) monoclonal antibody. Lenzilumab is a monoclonal antibody that has been demonstrated to neutralize GM-CSF, a cytokine that the Company believes is of critical importance in the hyperinflammatory cascade, sometimes referred to as cytokine release syndrome (“CRS”) or cytokine storm, associated with COVID-19, chimeric antigen receptor T-cell (“CAR-T”) therapy and acute Graft versus Host Disease (“aGvHD”) associated with bone marrow transplants. The Company believes the results from its Phase 3 study in COVID-19, its Phase 1b study in CAR-T, and four other clinical trials, support the mechanism of action of lenzilumab. On May 5, 2021, data from the Company’s Phase 3, multi-center, double-blind, placebo-controlled potential registrational trial of lenzilumab as a potential therapeutic for hospitalized, hypoxic patients with COVID-19 pneumonia was published on MedRxiv, a non-peer reviewed journal. The Company refers to this study as the “LIVE-AIR” study. Data from LIVE-AIR support the previously reported primary endpoint that demonstrated lenzilumab improved the likelihood of survival without ventilation, (“SWOV”), sometimes referred to as “ventilator-free survival”, by 54% in the modified intent-to-treat (“mITT”) population (Hazard Ratio, (“HR”): 1.54; 95%CI: 1.02-2.32, p=0.0403). SWOV also improved on a relative basis by 92% in subjects who received both corticosteroids and remdesivir (1.92; 1.20-3.07, nominal p=0.0067); by 3.04-fold in subjects with baseline C-reactive protein (“CRP”) levels <150 mg/L and age <85 years (3.04; 1.68–5.51, nominal p=0.0003). Survival was improved by 2.22-fold in subjects with baseline CRP<150 mg/L and age <85 years (nominal p=0.0337). Subjects in the LIVE-AIR study with baseline CRP<150 mg/L and age <85 years, 75% of all patients with an evaluable CRP at baseline, demonstrated an improvement in survival and appeared to derive the greatest benefit from lenzilumab. The Company submitted an application for Emergency Use Authorization (“EUA”) of lenzilumab to the U.S. Food and Drug Administration (“FDA”) at the end of May 2021. On September 8, 2021, FDA declined the Company’s EUA request. FDA committed to working with the Company in the development of lenzilumab and invited the Company to submit additional data as it becomes available. The Company requested and has been granted a Type B meeting with FDA. Included in the briefing materials for the meeting request were day 60 data as well as detailed CRP analysis from the Company’s LIVE-AIR Phase 3 study. The Company has submitted to the Medicines and Healthcare Products Regulatory Agency (“MHRA”), the pharmaceuticals and biologics regulatory agency in the United Kingdom (“UK”), all the required modules as well as a risk management plan and pediatric investigation plan for a Conditional Marketing Authorization (“CMA”) for the use of lenzilumab in hospitalized COVID-19 patients. The Company has also initiated the process for submission to the European Medicines Agency (“EMA”) of a Marketing Authorization Application (“MAA”) for the use of lenzilumab in the European Union and the EMA has appointed a rapporteur and co-rapporteur as part of the process related to this submission. Lenzilumab was selected to be part of the ongoing Accelerating COVID-19 Therapeutic Interventions and Vaccines (“ACTIV”)-5 and Big Effect Trial, in the “B” arm of the trial (“BET-B”), referred to as the ACTIV-5/BET-B trial, which is sponsored and funded by the National Institutes of Health (“NIH”). ACTIV-5/BET-B currently has over 53 active U.S. sites and two Korean sites enrolling and has recently expanded to a potential of 70 sites. The study is evaluating lenzilumab in combination with remdesivir, compared to placebo and remdesivir, in hospitalized COVID-19 patients with a 1:1 randomization. In July 2021, NIH advanced the ACTIV-5/BET-B study to a Phase 2/3 study and amended the protocol in a manner that aligns with the design of the LIVE-AIR study. The amended ACTIV-5/BET-B study protocol now includes target enrollment of up to 400 patients with a baseline CRP<150 mg/L, or up to 550 patients overall. Humanigen is providing lenzilumab and assisting the NIH to achieve the completion of the study. The Company intends to submit a Biologics License Application (“BLA”) to FDA for lenzilumab in the treatment of hospitalized COVID-19 patients. Since BLAs typically require more than one study, the Company plans to include the results of the expanded ACTIV-5/BET-B study as a basis for a BLA-confirmatory study for lenzilumab and believes data from ACTIV-5/BET-B, along with LIVE-AIR, should provide the sufficient size and statistical power typically required for a BLA to be submitted to FDA. 7 Table of Contents Lenzilumab also has been studied in a multi-center Phase 1b trial as a sequenced therapy with Yescarta® (axicabtagene ciloleucel) to prevent CRS and neurotoxicity in patients with relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”) (NCT04314843), for which the Company announced positive results. The Company intends to initiate a randomized, placebo-controlled, open-label, potentially registrational, Phase 3 study to evaluate the efficacy and safety of lenzilumab combined with commercially available CD19 CAR-T therapies in non-Hodgkin lymphoma in 2022 and has scheduled a meeting with FDA in December 2021 to discuss the study protocol. The Company currently plans to enroll approximately 250 patients in the study. The Company also expects that a Phase 2/3, potentially registrational, trial for lenzilumab to treat patients who have undergone allogeneic hematopoietic stem cell therapy (“HSCT”) who are at high and intermediate risk for acute GvHD (the “Risk Adapted Therapy in Acute GvHD” or the “RATinG” study) is expected to begin enrollment in the first half of 2022. The study will be conducted by the IMPACT Partnership, a collection of 22 stem cell transplant centers located in the UK. The Company will provide lenzilumab for the study including the cost of import, labeling and distribution of the study drug, and support certain laboratory tests related to the study, but the majority of the study costs will be borne by the IMPACT Partnership. In addition, the Company is in partnership with the South Australian Health & Medical Research Institute (“SAHMRI”) and the University of Adelaide to conduct a Phase 2 trial studying the efficacy of lenzilumab in combination with azacitadine in patients with chronic myelomonocytic leukemia (“CMML”). The study (“PREcision Approach to Chronic Myelomonocytic Leukemia” or “PREACH-M”) has begun enrollment at five sites in Australia and the first patient has been dosed. The Company will provide lenzilumab for this study and the majority of the study costs will be borne by the partner and funded by a grant from the Medical Research Futures Fund, a research fund set up by the Australian Government. The Company’s proprietary, patented Humaneered technology platform is a method for converting existing antibodies (typically murine) into engineered, high-affinity human antibodies designed for therapeutic use, particularly with acute and chronic conditions. The Company has developed or in-licensed targets or research antibodies, typically from academic institutions, and then applied its Humaneered technology to optimize them. Lenzilumab and the Company’s other two product candidates, ifabotuzumab and HGEN005, are Humaneered monoclonal antibodies. The Company’s Humaneered antibodies are closer to human antibodies than chimeric or conventionally humanized antibodies and have a high affinity for their target but low immunogenicity. In addition, the Company believes its Humaneered antibodies offer further important advantages, such as high potency, a slow off-rate and a lower likelihood to induce an inappropriate immune response or infusion related reactions. 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 Condensed Consolidated Financial Statements for the three and nine months ended September 30, 2021 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. However, the Company has incurred net losses since its inception and has negative operating cash flows. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. The financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern. The Company continues to advance its efforts in support of the development of lenzilumab as a therapy for hospitalized COVID-19 patients. As of September 30, 2021, the Company had cash and cash equivalents of $76.5 million. On September 8, 2021, FDA declined to approve the Company’s EUA for lenzilumab. As more fully described in our Annual Report on Form 10-K for the year ended December 31, 2020 under “Item 1. Business—Manufacturing and Raw Materials.”, the Company has entered into agreements with several contract manufacturing organizations (“CMOs”) to provide manufacturing, fill/finish and packaging services for lenzilumab. While the Company remains committed to its ongoing efforts seeking marketing authorization for lenzilumab to treat hospitalized COVID-19 patients in the U.S., UK and other territories, the Company has amended, and in some cases canceled, certain of these agreements, some of which were contingent on EUA, in an effort to reduce its future spending on lenzilumab production until and if authorization is received in the UK, European Union (“EU”), or U.S. (See Note 6 below). These changes will significantly limit future production of lenzilumab but, because most of the Company’s manufacturing agreements required payment of upfront fees upon execution and payments against performance of the services to be provided, often over a lengthy performance period, the changes will not have an immediate impact on the Company’s spending as the cancellations generally only impact production efforts that were not expected to commence until 2022. 8 Table of Contents Considering the Company’s current cash resources and its current and expected levels of operating expenses, management expects to need additional capital to fund the Company’s planned operations for the next twelve months. Management may seek to raise such additional capital through public or private equity offerings, including under the Controlled Equity Offering SM Reclassifications Certain prior year amounts in the Condensed Consolidated Financial Statements have been reclassified to conform to the current year's presentation. Such reclassifications had no effect on prior years’ Net loss or Stockholders’ equity (deficit). 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, 2020 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, 2021, 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 2020 Annual Report on 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 accounting for the determination of revenue recognition, fair value-based measurement of stock-based compensation, accruals 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 Condensed Consolidated Financial Statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The Company’s significant accounting policies are detailed in its Annual Report on Form 10-K for the year ended December 31, 2020. There have been no significant changes to the Company’s significant accounting policies during the three and nine months ended September 30, 2021 from those previously disclosed in its 2020 Annual Report on Form 10-K. Recent Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, Simplifying the Accounting for Income Taxes. ASU No. 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company adopted No. ASU 2019-12 on January 1, 2021, which did not have any impact to the Company’s Condensed Consolidated Financial Statements. In August 2020, the FASB issued ASU No. 2020-06, “Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity”, as part of its overall simplification initiative to reduce costs and complexity of applying accounting standards while maintaining or improving the usefulness of the information provided to users of financial statements. Among other changes, the new guidance removes from U.S. GAAP, separation models for convertible debt that require the convertible debt to be separated into a debt and equity component, unless the conversion feature is required to be bifurcated and accounted for as a derivative or the debt is issued at a substantial premium. As a result, after adopting the guidance, entities will no longer separately present such embedded conversion features in equity and will instead account for the convertible debt wholly as debt. The new guidance also requires use of the “if-converted” method when calculating the dilutive impact of convertible debt on earnings per share, which is consistent with the Company’s current accounting treatment under the current guidance. The guidance is effective for the Company’s financial statements issued for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years, with early adoption permitted, but only at the beginning of the fiscal year. The Company early adopted the new guidance on January 1, 2021, using the modified retrospective approach. The adoption did not have any impact to the Company’s Condensed Consolidated Financial Statements.

Potentially Dilutive Securities

Potentially Dilutive Securities	9 Months Ended
	Sep. 30, 2021
Potentially Dilutive Securities
Potentially Dilutive Securities	3. Potentially Dilutive Securities The Company’s potentially dilutive securities, which include stock options and warrants and shares of common stock issuable upon conversion of convertible debt, 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 September 30, 2021 2020 Options to purchase common stock 4,144,864 3,528,642 Warrants to purchase common stock 31,238 76,238 Convertible debt 510,986 - 4,687,088 3,604,880

License Revenue

License Revenue	9 Months Ended
	Sep. 30, 2021
License Revenue
License Revenue	4. License Revenue On November 3, 2020, the Company entered into a License Agreement (the “South Korea Agreement”) with KPM Tech Co., Ltd. (“KPM”) and its affiliate, Telcon RF Pharmaceutical, Inc. (together with KPM, the “Licensee”). Pursuant to the South Korea Agreement, among other things, the Company granted the Licensee a license under certain patents and other intellectual property to develop and commercialize lenzilumab for treatment of COVID-19 pneumonia, in South Korea and the Philippines (the “Territory”), subject to certain reservations and limitations. The Licensee will be responsible for gaining regulatory approval for, and subsequent commercialization of, lenzilumab in the Territory. As consideration for the license, the Licensee has agreed to pay the Company (i) an up-front license fee of $6.0 million (or $4.5 million net of withholding taxes and other fees and royalties), payable promptly following the execution of the License Agreement, which was received in the fourth quarter of 2020, (ii) up to an aggregate of $14.0 million in two payments based on achievement by the Company of two specified milestones in the U.S., of which the first milestone was met in the first quarter of 2021 and $6.0 million (or $4.5 million net of withholding taxes and other fees and royalties) was received in the second quarter of 2021, and (iii) subsequent to the receipt by the Licensee of the requisite regulatory approvals, double-digit royalties on the net sales of lenzilumab in South Korea and the Philippines. The Licensee has agreed to certain development and commercial performance obligations. It is expected that the Company will supply lenzilumab to the Licensee for a minimum of 7.5 years at a cost-plus basis from an existing or future manufacturer. The Licensee has agreed to certain minimum purchases of lenzilumab on an annual basis. The Company assessed the South Korea Agreement in accordance with Accounting Standards Codification (“ASC”) 606 – Revenue from Contracts with Customers Collaborative Arrangements The Company has concluded that the nature of its promise is to stand ready to provide Research and Development Services as needed during the Performance Period (as defined below). The Company has further concluded that for all of the increments of time during the Performance Period its promise of standing ready to provide the Services is substantially the same. While the specific tasks performed during each increment of time will vary, the nature of the overall promise to provide the Services remains the same throughout the Performance Period. 10 Table of Contents Since the provision of the license and the Services are considered a single performance obligation, the $6.0 million upfront payment (or $4.5 million net of withholding taxes and other fees and royalties) and the first milestone payment of $6.0 million (or $4.5 million net of withholding taxes and other fees and royalties) which was met in the first quarter of 2021 and received in the second quarter of 2021, are being recognized as revenue ratably over the performance period through March 2023 (the “Performance Period”), the expected period over which the Company conservatively expects the Services to be performed with approval in the Territory expected by the end of March 2023. Therefore, in the three and nine months ended September 30, 2021, the Company recognized license revenue totaling approximately $1.0 million and $2.6 million, respectively. Licensee’s purchases of lenzilumab for development purposes or for commercial requirements, represent options under the agreement and revenues will therefore be recognized when control of the product is transferred to Licensee.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Long-Term Debt	5. Long-Term Debt Secured Term Loan Facility On March 10, 2021, the Company executed a Loan and Security Agreement with Hercules Capital as agent for its affiliates serving as lenders thereunder (the “Term Loan”). The Term Loan provides a loan in the aggregate principal amount of up to $80 million, in three tranches. On March 29, 2021, the Company drew the initial $25.0 million tranche under the Term Loan. After giving effect to payment of fees and expenses associated with the draw, the Company received net proceeds of approximately $24.4 million. The Company is no longer entitled to draw the second tranche, which was to be in the amount of $35.0 million or $25.0 million, as it did not receive EUA for lenzilumab for the treatment of hospitalized patients with COVID-19 pneumonia by September 15, 2021. The Company may become entitled to draw another $20.0 million under the Term Loan through June 15, 2022, at the discretion of Hercules if the Company requests additional funding in support of the Company’s strategic initiatives, although there can be no assurances that Hercules would agree to provide such additional funding. The Company will be required to repay amounts borrowed by March 1, 2025, subject to a one-year extension option that it may exercise if it has received FDA approval of a BLA for the use of lenzilumab for the treatment of hospitalized patients with COVID-19 pneumonia, and the FDA-authorized label for lenzilumab is generally consistent with that sought in the Company’s BLA filing, and the Company has paid Hercules certain fees and expenses associated with the extension. Amounts drawn bear interest at a floating rate equal to the greater of either (i) 8.75% plus the prime rate as reported in The Wall Street Journal minus 3.25%, or (ii) 8.75% (such greater amount, the “Base Interest Rate”). Subject to there not having occurred any default or event of default under the loan agreement, the Base Interest Rate will be reduced by 25 basis points upon the occurrence of each of the first three of the four following events to occur: • if the Company achieves the protocol-specified primary efficacy endpoint for the pivotal Phase 3 study of lenzilumab for COVID-19, (clinicaltrials.gov identifier NCT04351152), and receives EUA for the use of lenzilumab for the treatment of hospitalized patients with COVID-19 pneumonia; • if the Company achieves product revenue from lenzilumab that is invoiced and/or recognized as revenue (as determined in accordance with GAAP) solely from the sale of lenzilumab (“Net Lenzilumab Product Revenue”) of at least $100.0 million; • if the Company achieves Net Lenzilumab Product Revenue of at least $250.0 million; and • if the Company achieves Net Lenzilumab Product Revenue of at least $350.0 million. No principal payments will be due during an interest-only period, commencing on the initial borrowing date and continuing to April 1, 2023, subject to extension to April 1, 2024, and potentially October 1, 2024, under certain conditions. Following the interest-only period, the outstanding balance of the loan will be required to be repaid monthly, continuing through the maturity date. The Company may prepay amounts drawn under the agreement in full prior to the maturity date then in effect, subject to payment of prepayment charges equal to: • 2.0% of the amounts borrowed, if the prepayment occurs on or prior to March 29, 2022; • 1.5% of the amounts borrowed, if the prepayment occurs after March 29, 2022 and before March 29, 2023; and • 1.0% of the amounts borrowed, if the prepayment occurs after March 29, 2023 and before March 29, 2024. In addition, on the earliest to occur of (i) the maturity date, (ii) the date the Company prepays the outstanding principal amount of the Term Loan, or (iii) the date the outstanding principal amount of the Term Loan otherwise becomes due, the Company will owe Hercules an end of term (“EOT”) charge equal to 6.75% of the aggregate amount of the Term Loan funded by Hercules. As a condition to obtaining the Term Loan, the Company granted Hercules a security interest in substantially all of its assets and personal property not otherwise subject to existing or permitted liens. In addition, the Term Loan contains customary representations and warranties and events of default for a term loan facility of this size and type. Under the Term Loan, the Company also agreed to comply with certain customary affirmative and negative covenants that become effective upon the initial draw of the first tranche, including covenants to: 11 Table of Contents • maintain $10.0 million unrestricted cash; • comply with certain requirements to provide Hercules with financial information and other rights to inspect the Company’s books and records and the collateral for the Term Loan; • refrain from incurring debt that is not expressly subordinated to the Term Loan; “Rule 144A-style” convertible notes in aggregate principal amount up to $250.0 million; and other permitted indebtedness; • refrain from granting (or permitting to exist) liens on the Company’s assets and properties, other than certain permitted liens, including in respect of its patents and other intellectual property; • refrain from making certain investments, other than permitted acquisitions and certain other permitted investments; • refrain from repurchasing the Company’s stock or paying dividends, subject to limited exceptions; • refrain from transferring any material portion of its assets; and • refrain from entering into any merger or consolidation in which the Company is not the surviving entity. All of these covenants will not apply upon repayment of any borrowings under the Term Loan. Certain of the baskets for permitted investments and other exceptions to the covenants described above have increased because the Company has raised more than $100.0 million in unrestricted net cash proceeds from one or more bona fide equity financings prior to March 31, 2022. (See Notes 7 and 11 below for information relating to the Company’s equity financings in 2021 in this regard.) Further, the covenants in the Term Loan will not prohibit the Company from pursuing its strategy of entering into out-bound license agreements for lenzilumab that may be exclusive as to specific geographic regions outside the U.S., nor will the covenants prohibit the Company from entering into co-development or co-promotion or commercialization agreements relating to lenzilumab, so long as such agreements generally are negotiated on arm’s length and commercially reasonable terms. While the Term Loan is outstanding, the lenders will have the right to convert a portion of the principal amount outstanding under the Term Loan (ranging from $5.0 million to $10.0 million in the aggregate) into shares of the Company’s common stock at a conversion price equal to $19.57 per share, subject to customary anti-dilution adjustments. The following table summarizes the outstanding future payments of principal and interest associated with the Company’s Term Loan as of September 30, 2021 (in thousands): 2021 $ 552 2022 2,218 2023 10,800 2024 13,671 2025 5,153 Total payments 32,394 Less amount representing interest (5,706 ) Notes payable, gross 26,688 Less: Unamortized portion of EOT charge (1,406 ) Less: Unamortized discount on notes payable (177 ) Less: Unamortized debt issuance costs (287 ) Long-term debt 24,818 Less current portion - Long-term debt, net of current portion $ 24,818 Interest expense related to the Term Loan, for the three and nine months ended September 30, 2021 was approximately $0.7 million and $1.5 million, respectively, and the effective interest rate was 9.0%.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Eversana Agreement On January 10, 2021, the Company announced that it had entered into a master services agreement (the “Eversana Agreement”) with Eversana Life Science Services, LLC (“Eversana”) pursuant to which Eversana will provide the Company multiple services from its integrated commercial platform in preparation for the potential commercialization of lenzilumab. Under the Eversana Agreement, Eversana will provide the Company with services in connection with the potential launch of lenzilumab. Eversana services during 2021 have comprised marketing, market access, consulting, field solutions, field operations, health economics and medical affairs. Additional services may be negotiated by the parties and set forth in statements of work delivered in accordance with the Eversana Agreement. The Company agreed to pay Eversana fees and reimburse it for expenses in performing the services as established in applicable statements of work. Eversana agreed to defer a portion of its fees for certain work performed which fees would only be payable upon the Company’s receipt of an EUA from FDA for lenzilumab for newly hospitalized and hypoxic COVID-19 patients.On September 21, 2021, the Company notified Eversana that due to the declination letter received from FDA on September 8, 2021, it was terminating the initial statement of work related to commercialization support of lenzilumab for the treatment of COVID-19 in the United States. Eversana is disputing the termination notice and has requested payment of approximately $4.0 million for services rendered from April 1, 2021 to September 30, 2021. The parties are working to resolve a dispute over the amount of fees the Company is obligated to pay Eversana as a result of FDA’s decision to decline to grant EUA for lenzilumab. The Eversana Agreement provides for a one-year term and will renew for subsequent one-year terms unless either party provides a notice of non-renewal. After the first year, the Company may terminate the Eversana Agreement upon advance written notice to Eversana. The Eversana Agreement contains customary provisions allowing either party to terminate the Eversana Agreement as a result of certain changes in law and material breaches and certain insolvency events by or relating to the other party. The Eversana Agreement imposes customary mutual obligations on the parties to protect and not disclose the confidential information and intellectual property of the other, and contains insurance, non-solicitation, indemnification and limitation of liability provisions customary for service contracts of this type. Manufacturing Agreements The Company has entered into agreements with several CMOs to manufacture bulk drug substance (“BDS”) and fill/finish/drug product (“DP”) for lenzilumab for a potential launch of lenzilumab in anticipation of an EUA or CMA in 2021. The Company has also entered into agreements for packaging of the drug. These agreements represent large commitments, including upfront amounts prior to commencement of manufacturing and progress payments through the course of the manufacturing process and include payments for technology transfer. Since September 9, 2021, the Company has amended, and in some cases canceled, certain of these agreements, some of which were contingent on EUA, in an effort to reduce its future spending on lenzilumab production until and if authorization is received in the UK, EU, or U.S. These changes will significantly limit future production of lenzilumab but because most of the Company’s manufacturing agreements required payment of upfront fees upon execution and payments against performance of the services to be provided, often over a lengthy performance period, the changes will not have an immediate impact on the Company’s spending as the cancellations generally only impact production efforts that were not expected to commence until 2022. In addition, certain of the Company’s CMOs have been unsuccessful in their efforts to manufacture some batches of lenzilumab to the Company’s specifications for various reasons. The Company is working with these CMOs to determine if batches of BDS manufactured by them will be usable in the future or, if not, whether other financial recompense will be offered to the Company. As of September 30, 2021, the Company estimates that its commitments remaining to be incurred under these agreements are approximately $50.5 million for the fourth quarter of 2021, $55.9 million for 2022 and $4.3 million thereafter. Certain of these commitments and amounts accrued at quarter-end are in dispute and the Company intends to defer these payments, negotiate lower amounts or seek legal recourse for the amounts in question.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Reverse Stock Split Effective September 11, 2020 (the “Effective Date”), the Company amended its charter to effect a reverse stock split at a ratio of 1-for-5 (the “Split Ratio”). No fractional shares were issued in connection with the reverse stock split. Stockholders of record otherwise entitled to receive fractional shares of common stock received cash (without interest or deduction) in lieu of such fractional share interests. 13 Table of Contents The reverse stock split reduced the total number of shares of the Company’s common stock outstanding as of the Effective Date from approximately 210.9 million shares to approximately 42.2 million shares. The par value per share and other terms of the Company’s common stock were not affected by the reverse stock split, and the number of authorized shares of the Company’s common stock remains at 225,000,000. The reverse stock split resulted in a proportionate adjustment in the number of shares reserved for issuance under the 2020 Equity Plan, such that a total of 7,000,000 shares of the Company’s common stock were reserved for issuance under the 2020 Equity Plan following the Effective Date. In addition, proportionate adjustments were made to the number of shares covered by, and the exercise price applicable to, each outstanding stock option award under the 2012 Equity Plan and outstanding warrants issued by the Company, in each case to give effect to the Split Ratio and the reverse stock split. The reverse stock split was accounted for retroactively and is reflected in our common stock, stock option and warrant activity as of and during the period ended December 31, 2020, and the periods ended September 30, 2021 and 2020. Unless stated otherwise, all share data in this Quarterly Report on Form 10-Q have been adjusted, as appropriate, to reflect the reverse stock split. Controlled Equity Offering On December 31, 2020, the Company entered into the Sales Agreement with Cantor, under which the Company could issue and sell from time-to-time shares of the Company’s common stock, having an aggregate gross sales price of up to $100 million through Cantor, as sales agent. During the nine months ended September 30, 2021, the Company issued and sold 2,397,791 shares of common stock pursuant to the Sales Agreement, and received net proceeds of approximately $40.0 million, after deducting fees and expenses. As of September 30, 2021, the Company had the ability to offer and sell shares of common stock having an aggregate offering price of up to $58.7 million under the prospectus supplement dated August 13, 2021 to the Company’s prospectus dated September 14, 2020 filed in respect of the Sales Agreement. See Note 11 below for additional information related to the Sales Agreement. 2021 Underwritten Public Offering On March 30, 2021, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC, Credit Suisse Securities (USA) LLC and Cantor, as representatives of the several` underwriters (the “Underwriters”), in connection with the public offering of 5,000,000 shares of the Company’s common stock. Pursuant to the Underwriting Agreement, the Company granted the underwriters a 30-day option to purchase an additional 750,000 shares of common stock. The initial sale of 5,000,000 shares closed on April 5, 2021. On May 3, 2021, the Company closed on the sale of an additional 427,017 shares of its common stock related to the exercise of the underwriters’ 30-day option. The net proceeds from this offering, after deducting underwriting discounts and offering costs were approximately $94.2 million.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation A summary of stock option activity for the nine months ended September 30, 2021 under all the Company’s options plans is as follows: Options Weighted Average Exercise Price Outstanding at January 1, 2021 3,732,149 $ 5.57 Granted 1,049,355 $ 15.66 Exercised (582,936 ) $ 3.98 Cancelled (forfeited) (53,600 ) $ 7.71 Cancelled (expired) (104 ) $ 162.09 Outstanding at September 30, 2021 4,144,864 $ 8.32 The weighted average fair value of options granted during the nine months ended September 30, 2021 was $12.87 per share. 14 Table of Contents The Company valued the options granted using the Black-Scholes options pricing model and the following weighted-average assumption terms for the nine months ended September 30, 2021: Nine Months Ended September 30, 2021 Exercise price $5.93 - $20.68 Market value $5.93 - $20.68 Expected term 5 - 6 years Expected volatility 105% - 109% Risk-free interest rate 0.98% - 1.09% Expected dividend yield -% The Company recorded stock-based compensation expense in the Condensed Consolidated Statements of Operations as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 General and administrative $ 1,077 $ 909 $ 2,848 $ 1,415 Research and development 357 103 967 219 Total stock-based compensation $ 1,434 $ 1,012 $ 3,815 $ 1,634 At September 30, 2021, the Company had $12.5 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 2.2 years.

License and Collaboration Agree

License and Collaboration Agreements	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
License and Collaboration Agreements	9. License and Collaboration Agreements Kite Agreement On May 30, 2019, the Company entered into a clinical collaboration agreement with Kite, providing in part for conduct of a multi-center Phase 1b study of lenzilumab with Kite’s Yescarta in patients with relapsed or refractory B-cell lymphoma, including DLBCL. On April 19, 2021, the Company announced positive preliminary data from this study. As a result of this positive preliminary data and the conclusion of the Phase 1b portion of the study, the Company elected to terminate the clinical collaboration agreement with Kite. Enrollment in the Phase 1b portion of the study is closed and the study itself shall be closed by the fourth quarter of 2021. The effective date of termination of the clinical collaboration with Kite shall be December 31, 2021. Until the Phase 1b portion of the study is terminated and the last subject transitioned onto the Kite long term follow up protocol, Humanigen and Kite will cooperate to ensure the orderly wind down of study activities. The Company is preparing to initiate a Company-sponsored Phase 3 study with commercially available CD19 CAR-T therapies in non-Hodgkin lymphoma in 2022 and has scheduled a meeting with FDA in December 2021 to discuss the study protocol. The Company currently plans to enroll approximately 250 patients in 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 KO Pursuant to the Mayo Agreement, the Company paid $0.2 million to Mayo in June 2020, which payment was accrued as Research and development expense in June 2019. The Mayo Agreement also requires the payment of milestones and royalties upon the achievement of certain regulatory and commercialization milestones. 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 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”). The Zurich Agreement also requires the payment of annual maintenance fees and milestones and royalties upon the achievement of certain regulatory and commercialization milestones. 15 Table of Contents Clinical Trial Agreement with the National Institute of Allergy and Infectious Diseases On July 24, 2020, the Company entered into a clinical trial agreement (the “ACTIV-5 Clinical Trial Agreement”) with the National Institute of Allergy and Infectious Diseases (“NIAID”), part of NIH, which is part of the U.S. Government Department of Health and Human Services, as represented by the Division of Microbiology and Infectious Diseases. Pursuant to the ACTIV-5 Clinical Trial Agreement, lenzilumab is being evaluated in the NIAID-sponsored ACTIV-5/BET-B in hospitalized patients with COVID-19. See Note 1 above for further information regarding ACTIV-5/BET-B. Pursuant to the ACTIV-5 Clinical Trial Agreement, NIAID will serve as sponsor and will be responsible for funding, supervising and overseeing ACTIV-5/BET-B. The Company will be responsible for providing lenzilumab to NIAID without charge and in quantities to ensure a sufficient supply of lenzilumab. The ACTIV-5 Clinical Trial Agreement imposes additional obligations on the Company that are reasonable and customary for clinical trial agreements of this nature, including in respect of compliance with data privacy laws and potential indemnification obligations. The Company will have access to data from ACTIV-5/BET-B once concluded. CRADA On November 5, 2020, the Company and the Department of Defense (“DoD”) Joint Program Executive Office for Chemical, Biological, Radiological and Nuclear Defense (“JPEO-CBRND” or “JPEO”) entered into a Cooperative Research and Development Agreement (“CRADA”) in collaboration with the Biomedical Advanced Research and Development Authority (“BARDA”), part of the Office of the Assistant Secretary for Preparedness and Response (“ASPR”) at the U.S. Department of Health and Human Services (“HHS”), in support of Operation Warp Speed (“OWS”), to assist in the development of lenzilumab, in connection with a potential EUA for COVID-19. On January 22, 2021, the Company announced an expansion of the CRADA that it had previously entered into with JPEO on November 5, 2020, was subsequently co-signed by BARDA and is set to expire on January 21, 2022. This provides the Company with access to manufacturing capacity reserved by BARDA for fill-finish product to accelerate the drug product manufacturing of lenzilumab. Pursuant to the CRADA, the Company has been provided access to a full-scale, integrated team of OWS manufacturing, and regulatory subject matter experts, leading decision makers and statistical support in its efforts to apply for EUA for lenzilumab as a potential treatment for COVID-19.

Litigation

Litigation	9 Months Ended
	Sep. 30, 2021
Litigation Settlement [Abstract]
Litigation	10. Litigation Savant Litigation The Company is currently involved in litigation with Savant Neglected Diseases, LLC (“Savant”) in an action captioned Humanigen, Inc. v. Savant Neglected Diseases, LLC Subsequently, Savant filed a complaint against the Company and Madison Joint Venture LLC (“Madison”) in the Delaware Court of Chancery (the “Chancery Action”) seeking to “recover as damages amounts owed to it under the MDC Agreement, and to reclaim Savant’s intellectual property,” among other things. This action was subsequently consolidated with the Superior Court action. On July 9, 2021, the Court issued a memorandum opinion resolving various summary judgment motions. In the opinion, the Court granted the Company’s motion for summary judgment on certain of Savant’s claims. Accordingly, Savant’s claims are now limited to breach of contract and fraudulent transfer claims. Savant’s summary judgment motion was denied in its entirety leaving Humanigen’s fraud and contract claims against Savant for trial. The action is not currently set for trial, but the Company is prepared to defend itself vigorously and pursue all remedies available against Savant for breach of contract and fraud. Private Placement Litigation On June 15, 2020, a complaint was filed against the Company and Dr. Durrant in the Commercial Division of the Supreme Court of the State of New York. The case caption is Alliance Texas Holdings, LLC et al. v. Humanigen, Inc. et al. 16 Table of Contents The Company believes that the claims made in the Alliance Texas Holdings Case are without merit, and it is prepared to defend itself vigorously. On April 19, 2021, the Company and Noble entered into a confidential settlement agreement in respect of a separate lawsuit brought by Noble related to the Private Placement (the “Noble Case”) captioned Noble Capital Markets, Inc. v. Humanigen, Inc., Case No. 9:20-CV-81131-WPD, pursuant to which the Noble Case was dismissed with prejudice.

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Event	11. Subsequent Event Subsequent to September 30, 2021 and through the date of this filing, the Company issued and sold 3,818,300 shares of common stock pursuant to the Sales Agreement and received net proceeds of approximately $24.5 million, after deducting fees and expenses. As of the date of this filing, the Company had the ability to offer and sell additional shares of common stock having an aggregate offering price of up to $33.5 million under the prospectus supplement dated August 13, 2021 to the Company’s prospectus dated September 14, 2020 filed in respect of the Sales Agreement.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, Simplifying the Accounting for Income Taxes. ASU No. 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company adopted No. ASU 2019-12 on January 1, 2021, which did not have any impact to the Company’s Condensed Consolidated Financial Statements. In August 2020, the FASB issued ASU No. 2020-06, “Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity”, as part of its overall simplification initiative to reduce costs and complexity of applying accounting standards while maintaining or improving the usefulness of the information provided to users of financial statements. Among other changes, the new guidance removes from U.S. GAAP, separation models for convertible debt that require the convertible debt to be separated into a debt and equity component, unless the conversion feature is required to be bifurcated and accounted for as a derivative or the debt is issued at a substantial premium. As a result, after adopting the guidance, entities will no longer separately present such embedded conversion features in equity and will instead account for the convertible debt wholly as debt. The new guidance also requires use of the “if-converted” method when calculating the dilutive impact of convertible debt on earnings per share, which is consistent with the Company’s current accounting treatment under the current guidance. The guidance is effective for the Company’s financial statements issued for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years, with early adoption permitted, but only at the beginning of the fiscal year. The Company early adopted the new guidance on January 1, 2021, using the modified retrospective approach. The adoption did not have any impact to the Company’s Condensed Consolidated Financial Statements.

Potentially Dilutive Securiti_2

Potentially Dilutive Securities (Tables)	9 Months Ended
	Sep. 30, 2021
Potentially Dilutive Securities
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 September 30, 2021 2020 Options to purchase common stock 4,144,864 3,528,642 Warrants to purchase common stock 31,238 76,238 Convertible debt 510,986 - 4,687,088 3,604,880

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2021
Disclosure Text Block [Abstract]
Schedule of Outstanding Future Payments Associated Company's Term Loan	The following table summarizes the outstanding future payments of principal and interest associated with the Company’s Term Loan as of September 30, 2021 (in thousands): 2021 $ 552 2022 2,218 2023 10,800 2024 13,671 2025 5,153 Total payments 32,394 Less amount representing interest (5,706 ) Notes payable, gross 26,688 Less: Unamortized portion of EOT charge (1,406 ) Less: Unamortized discount on notes payable (177 ) Less: Unamortized debt issuance costs (287 ) Long-term debt 24,818 Less current portion - Long-term debt, net of current portion $ 24,818

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Summary of Stock Option Activity	A summary of stock option activity for the nine months ended September 30, 2021 under all the Company’s options plans is as follows: Options Weighted Average Exercise Price Outstanding at January 1, 2021 3,732,149 $ 5.57 Granted 1,049,355 $ 15.66 Exercised (582,936 ) $ 3.98 Cancelled (forfeited) (53,600 ) $ 7.71 Cancelled (expired) (104 ) $ 162.09 Outstanding at September 30, 2021 4,144,864 $ 8.32
Schedule of Weighted-Average Assumption Terms	The Company valued the options granted using the Black-Scholes options pricing model and the following weighted-average assumption terms for the nine months ended September 30, 2021: Nine Months Ended September 30, 2021 Exercise price $5.93 - $20.68 Market value $5.93 - $20.68 Expected term 5 - 6 years Expected volatility 105% - 109% Risk-free interest rate 0.98% - 1.09% Expected dividend yield -%
Schedule of Stock-Based Compensation Expense	The Company recorded stock-based compensation expense in the Condensed Consolidated Statements of Operations as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 General and administrative $ 1,077 $ 909 $ 2,848 $ 1,415 Research and development 357 103 967 219 Total stock-based compensation $ 1,434 $ 1,012 $ 3,815 $ 1,634

Nature of Operations (Details)

Nature of Operations (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash and cash equivalents	$ 76,500		$ 67,737
Total proceeds	$ 134,140	$ 139,760
Controlled Equity Offering SM Sales Agreement [Member]
Company issued shares	3,818,300
Total proceeds	$ 24,500

Potentially Dilutive Securiti_3

Potentially Dilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	4,687,088	3,604,880
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	4,144,864	3,528,642
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	31,238	76,238
Convertible debt [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted net loss per common share	510,986

License Revenue (Details)

License Revenue (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
License Agreement Terms [Member]
Gross up-front license fee		$ 6
Aggregate licence payment received			$ 14
Description of licensing agreement		the Company will supply lenzilumab to the Licensee for a minimum of 7.5 years at a cost-plus basis from an existing or future manufacturer.
Revenue recognized performance obligation description of payment		over the performance period through March 2023 (the “Performance Period”), the expected period over which the Company conservatively expects the Services to be performed with approval in the Territory expected by the end of March 2023.
License revenue	$ 1	$ 2.6
Up-front Payment Arrangement [Member]
Upfront payment		$ 4.5

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 10, 2021	Mar. 29, 2024	Mar. 29, 2023	Mar. 29, 2022	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Mar. 29, 2021
Debt Instrument [Line Items]
Converted principal amount							$ 4,316
Secured Term Loan Facility [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 80,000
Drew amount								$ 25,000
Net proceeds	24,400
Net Lenzilumab Product Revenue	$ 100,000
Base interest rate	8.75%				9.00%	9.00%
Floating interest rate, deduction	3.25%
Base interest rate reduction, basis points	0.25%
Unrestricted cash	$ 10,000
Unrestricted net cash proceeds	$ 100,000
Conversion price	$ 19.57
Interest expense					$ 700	$ 1,500
End of term fee percentage	6.75%
Secured Term Loan Facility [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Percentage of amount borrowed if repayment occurs		1.00%	1.50%	2.00%
Secured Term Loan Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Net Lenzilumab Product Revenue	$ 250,000
Converted principal amount	5,000
Secured Term Loan Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Net Lenzilumab Product Revenue	350,000
Converted principal amount	10,000
Secured Term Loan Facility [Member] | Second tranche [Member] | Minimum [Member]
Debt Instrument [Line Items]
Drew amount	25,000
Secured Term Loan Facility [Member] | Second tranche [Member] | Maximum [Member]
Debt Instrument [Line Items]
Drew amount	35,000
Secured Term Loan Facility [Member] | Third tranche [Member]
Debt Instrument [Line Items]
Drew amount	$ 20,000

Long-Term Debt (Schedule of Out

Long-Term Debt (Schedule of Outstanding Future Payments Associated Company's Term Loan) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
2021	$ 552
2022	2,218
2023	10,800
2024	13,671
2025	5,153
Total payments	32,394
Less amount representing interest	(5,706)
Notes payable, gross	26,688
Less: Unamortized portion of EOT charge	(1,406)
Less: Unamortized discount on notes payable	(177)
Less: Unamortized debt issuance costs	(287)
Long-term debt	24,818
Less current portion
Long-term debt, net of current portion	$ 24,818

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	6 Months Ended
	Sep. 30, 2021USD ($)
Other Commitments [Line Items]
Commitments remaining, 2021	$ 50.5
Commitments remaining, 2022	55.9
Commitments remaining, thereafter	4.3
Eversana Agreement [Member]
Other Commitments [Line Items]
Payment requested for services rendered	$ 4

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ in Thousands	May 03, 2021	Apr. 05, 2021	Mar. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 11, 2020
Class of Stock [Line Items]
Reverse stock split				1-for-5
Common Stock, shares authorized upon the completion of the IPO				225,000,000		225,000,000	225,000,000
Total proceeds				$ 134,140	$ 139,760
Common stock, shares outstanding				60,017,333		51,626,508
Controlled Equity Offering SM Sales Agreement [Member]
Class of Stock [Line Items]
Total proceeds				$ 24,500
Company issued shares				3,818,300
Aggregate offering price of additional shares issued				$ 33,500
Controlled Equity Offering SM Sales Agreement [Member] | Cantor Fitzgerald & Co. [Member]
Class of Stock [Line Items]
Total proceeds				$ 40,000		$ 100,000
Company issued shares				2,397,791
Aggregate offering price of additional shares issued				$ 58,700
2021 Underwritten Public Offering [Member]
Class of Stock [Line Items]
Sale of additional shares of common stock	427,017
2021 Underwritten Public Offering [Member] | J.P. Morgan Securities LLC and Jefferies LLC [Member]
Class of Stock [Line Items]
Shares issued in public offering		5,000,000	5,000,000
Warrants to purchase common stock			750,000
Proceeds from sale of shares after offering costs			$ 94,200
2020 Equity Plan [Member]
Class of Stock [Line Items]
Shares available for future grant							7,000,000
Maximum [Member]
Class of Stock [Line Items]
Common stock, shares outstanding							210,900,000
Minimum [Member]
Class of Stock [Line Items]
Common stock, shares outstanding							42,200,000

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)$ / shares
Share-based Payment Arrangement [Abstract]
Weighted average fair value of options granted | $ / shares	$ 12.87
Unrecognized compensation expense | $	$ 12.5
Weighted average period for recognition	2 years 2 months 12 days

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule of Summary of Stock Option Activity) (Details)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Options
Outstanding at January 1, 2021 | shares	3,732,149
Granted | shares	1,049,355
Exercised | shares	(582,936)
Cancelled (forfeited) | shares	(53,600)
Cancelled (expired) | shares	(104)
Outstanding at September 30, 2021 | shares	4,144,864
Weighted Average Exercise Price
Outstanding at January 1, 2021 | $ / shares	$ 5.57
Granted | $ / shares	15.66
Exercised | $ / shares	3.98
Cancelled (forfeited) | $ / shares	7.71
Cancelled (expired) | $ / shares	162.09
Outstanding at September 30, 2021 | $ / shares	$ 8.32

Stock-Based Compensation (Sch_2

Stock-Based Compensation (Schedule of Weighted-Average Assumption Terms) (Details)	9 Months Ended
	Sep. 30, 2021$ / shares
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected dividend yield
Minimum [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Exercise price	$ 5.93
Market value	$ 5.93
Expected term	5 years
Expected volatility	105.00%
Risk-free interest rate	0.98%
Maximum [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Exercise price	$ 20.68
Market value	$ 20.68
Expected term	6 years
Expected volatility	109.00%
Risk-free interest rate	1.09%

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 1,434	$ 1,012	$ 3,815	$ 1,634
General And Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	1,077	909	2,848	1,415
Research And Development Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 357	$ 103	$ 967	$ 219

License and Collaboration Agr_2

License and Collaboration Agreements (Details) - USD ($) $ in Millions	6 Months Ended	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2021
Mayo Agreement [Member]
Amount paid in license agreement	$ 0.2
CRADA [Member]
License agreement expiry date		Jan. 21, 2022

Subsequent Event (Details)

Subsequent Event (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Subsequent Event [Line Items]
Total proceeds	$ 134,140	$ 139,760
Controlled Equity Offering SM Sales Agreement [Member]
Subsequent Event [Line Items]
Company issued shares	3,818,300
Total proceeds	$ 24,500
Aggregate offering price of additional shares issued	$ 33,500