Nature of Operations	6 Months Ended
Jun. 30, 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 developing its clinical stage immuno-oncology and immunology portfolio of monoclonal antibodies. The Company is currently focused on developing its novel human granulocyte-macrophage colony-stimulating factor (“GM-CSF”) neutralization and gene-knockout platforms and its portfolio of antibodies based on its proprietary Humaneered® monoclonal antibody technology and has initiated research in next-generation cell and gene therapies. 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 cytokines and chemokines, including IL-6, TNFa, IL-1, MCP-1, MIP-1a, and IP-10 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 “cytokine storm” as the production of cytokines and 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 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, ZUMA-19, is underway to measure the effect of lenzilumab in reducing CRS and neurotoxicity (NT), with a secondary endpoint of increased efficacy of Yescarta. The first patient was dosed with lenzilumab in ZUMA-19 on June 29, 2020. The 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 and critical, progressive viral pneumonia that can progress to acute respiratory distress syndrome (“ARDS”), respiratory failure and death. Publications have indicated 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 patients with COVID-19 in a Phase III study. Given the severity of the pandemic and the lack of approved therapies for COVID-19, the Company believes that this single Phase III study may be suitable for registration and depending on the results of this study may file for approval with the FDA. The Company has commenced enrollment in a multicenter randomized, placebo-controlled, double-blind clinical trial to assess whether lenzilumab can reduce the time to recovery in hospitalized subjects with severe or critical COVID-19 pneumonia. The first patient was dosed with lenzilumab on May 5, 2020. Lenzilumab was granted emergency single use Investigational New Drug Application (IND) authorization from the FDA (often referred to as compassionate use) to treat patients with COVID-19. On June 15, 2020, the Company announced that Mayo Clinic published (www.medrxiv.org/content/10.1101/2020.06.08.20125369v1) data derived from the compassionate use of lenzilumab in treatment of 12 patients hospitalized in the Mayo Clinic system. Under applicable FDA rules, a patient cannot receive a compassionate use drug unless FDA has issued an individual patient emergency IND authorization, which the Mayo Clinic requested from FDA prior to each individual patient dosing of lenzilumab. Accordingly, there was no randomized control group in the Mayo Clinic program. The Company did not pre-select patients to receive lenzilumab through the compassionate use program and did not deny any requests for compassionate use. Mayo Clinic clinicians solely determined the patients for which they would request emergency IND authorization from the FDA. 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 six months ended June 30, 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. 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. As described in more detail in Note 7, on June 1, 2020, the Company entered into a securities purchase agreement with certain accredited investors to complete a private placement of our common stock (the “Private Placement”). At the closing, the Company issued and sold 82,528,718 shares of its common stock at a purchase price of $0.87 per share, for aggregate gross proceeds of approximately $71.8 million. The Company used a portion of the proceeds to retire certain indebtedness, as further described in Note 4 - Debt. The Company expects to use the remaining proceeds from the Private Placement to fund its Phase III study of lenzilumab in COVID-19, its collaboration with Kite, initiate manufacturing activities in anticipation of potential receipt of an Emergency Use Authorization (“EUA”) from FDA and subsequent commercialization, and other development programs, as well as for working capital and other general corporate purposes. As of June 30, 2020, the Company had cash and cash equivalents of $41.8 million. 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 equity offerings, debt financings, and/or payments under new or existing licensing or collaboration agreements. While management believes this plan to raise additional funds will alleviate the conditions that raise substantial doubt, these plans are not entirely within its control and cannot be assessed as being probable of occurring. 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. If any of these events occur, the Company’s ability to achieve the development and commercialization goals would be adversely affected. 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’ equity (deficit).

Nature of Operations

6 Months Ended

Jun. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

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 developing its clinical stage immuno-oncology and immunology portfolio of monoclonal antibodies. The Company is currently focused on developing its novel human granulocyte-macrophage colony-stimulating factor (“GM-CSF”) neutralization and gene-knockout platforms and its portfolio of antibodies based on its proprietary Humaneered® monoclonal antibody technology and has initiated research in next-generation cell and gene therapies.

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 cytokines and chemokines, including IL-6, TNFa, IL-1, MCP-1, MIP-1a, and IP-10 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 “cytokine storm” as the production of cytokines and 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 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, ZUMA-19, is underway to measure the effect of lenzilumab in reducing CRS and neurotoxicity (NT), with a secondary endpoint of increased efficacy of Yescarta. The first patient was dosed with lenzilumab in ZUMA-19 on June 29, 2020.

The 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 and critical, progressive viral pneumonia that can progress to acute respiratory distress syndrome (“ARDS”), respiratory failure and death. Publications have indicated 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 patients with COVID-19 in a Phase III study. Given the severity of the pandemic and the lack of approved therapies for COVID-19, the Company believes that this single Phase III study may be suitable for registration and depending on the results of this study may file for approval with the FDA. The Company has commenced enrollment in a multicenter randomized, placebo-controlled, double-blind clinical trial to assess whether lenzilumab can reduce the time to recovery in hospitalized subjects with severe or critical COVID-19 pneumonia. The first patient was dosed with lenzilumab on May 5, 2020.

Lenzilumab was granted emergency single use Investigational New Drug Application (IND) authorization from the FDA (often referred to as compassionate use) to treat patients with COVID-19. On June 15, 2020, the Company announced that Mayo Clinic published (www.medrxiv.org/content/10.1101/2020.06.08.20125369v1) data derived from the compassionate use of lenzilumab in treatment of 12 patients hospitalized in the Mayo Clinic system. Under applicable FDA rules, a patient cannot receive a compassionate use drug unless FDA has issued an individual patient emergency IND authorization, which the Mayo Clinic requested from FDA prior to each individual patient dosing of lenzilumab. Accordingly, there was no randomized control group in the Mayo Clinic program. The Company did not pre-select patients to receive lenzilumab through the compassionate use program and did not deny any requests for compassionate use. Mayo Clinic clinicians solely determined the patients for which they would request emergency IND authorization from the FDA.

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 six months ended June 30, 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. 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.

As described in more detail in Note 7, on June 1, 2020, the Company entered into a securities purchase agreement with certain accredited investors to complete a private placement of our common stock (the “Private Placement”). At the closing, the Company issued and sold 82,528,718 shares of its common stock at a purchase price of $0.87 per share, for aggregate gross proceeds of approximately $71.8 million. The Company used a portion of the proceeds to retire certain indebtedness, as further described in Note 4 - Debt. The Company expects to use the remaining proceeds from the Private Placement to fund its Phase III study of lenzilumab in COVID-19, its collaboration with Kite, initiate manufacturing activities in anticipation of potential receipt of an Emergency Use Authorization (“EUA”) from FDA and subsequent commercialization, and other development programs, as well as for working capital and other general corporate purposes.

As of June 30, 2020, the Company had cash and cash equivalents of $41.8 million. 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 equity offerings, debt financings, and/or payments under new or existing licensing or collaboration agreements. While management believes this plan to raise additional funds will alleviate the conditions that raise substantial doubt, these plans are not entirely within its control and cannot be assessed as being probable of occurring. 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. If any of these events occur, the Company’s ability to achieve the development and commercialization goals would be adversely affected.

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’ equity (deficit).