Humanigen’s Budget Impact Model Demonstrates Lenzilumab’s Potential Positive Economic Value in Hospitalized COVID-19 Patients

• Overall analysis demonstrates treatment with lenzilumab may result in both clinical and economic benefits in the majority of hospitalized patients
• Potential clinical and economic benefits are greater in certain patient populations

BURLINGAME, Calif.--(BUSINESS WIRE)-- Humanigen, Inc. (Nasdaq: HGEN) (“Humanigen”), a clinical-stage biopharmaceutical company focused on preventing and treating an immune hyper-response called ‘cytokine storm,’ announced that a manuscript describing its budget impact model for the treatment of patients hospitalized with COVID-19 is available on medRxiv (link). These results highlight the value of selecting the right treatment for the right hospitalized patients during this time of unprecedented pressure on health systems.

The cost to care for a COVID-19 patient in the ICU can significantly exceed $100,000 and average costs for patients on invasive mechanical ventilation in ICU amount to $78,245 per patient.¹ Lenzilumab is an investigational product and is not currently authorized or approved in any country.

About Humanigen

Humanigen, Inc. (Nasdaq: HGEN) (“Humanigen”), is a clinical-stage biopharmaceutical company focused on preventing and treating an immune hyper-response called ‘cytokine storm’. Lenzilumab is a first-in class antibody that binds to and neutralizes granulocyte-macrophage colony-stimulating factor (GM-CSF). Results from preclinical models indicate GM-CSF is an upstream regulator of many inflammatory cytokines and chemokines involved in the cytokine storm. Early in the COVID-19 pandemic, investigation showed high levels of GM-CSF secreting T cells were associated with disease severity and intensive care unit admission. Humanigen’s Phase 3 LIVE-AIR study suggests early intervention with lenzilumab may prevent consequences of a full-blown cytokine storm in hospitalized patients with COVID-19. Humanigen is developing lenzilumab as a treatment for cytokine storm associated with COVID-19 and CD19-targeted CAR-T cell therapies and is also exploring the effectiveness of lenzilumab in other inflammatory conditions such as acute Graft versus Host Disease in patients undergoing allogeneic hematopoietic stem cell transplantation, eosinophilic asthma, and rheumatoid arthritis. For more information, visit www.humanigen.com and follow Humanigen on LinkedIn, Twitter, and Facebook.

Forward-Looking Statements

All statements other than statements of historical facts contained in this press release are forward-looking statements. Forward-looking statements reflect management's current knowledge, assumptions, judgment, and expectations regarding future performance or events. Although management believes that the expectations reflected in such statements are reasonable, they give no assurance that such expectations will prove to be correct, and you should be aware that actual events or results may differ materially from those contained in the forward- looking statements. Words such as "will," “may,” "expect," "intend," "plan," "potential," "possible," "goals," "accelerate," "continue," and similar expressions identify forward-looking statements, including, without limitation, statements regarding potential clinical and economic benefits resulting from treatment with lenzilumab; our plans relating to further development of lenzilumab for indications other than COVID-19.

Forward-looking statements are subject to a number of risks and uncertainties including, but not limited to, the risks inherent in our lack of profitability and need for additional capital to grow our business; our dependence on partners to further the development of our product candidates; the uncertainties inherent in the development, attainment of the requisite regulatory authorizations and approvals and launch of any new pharmaceutical product; the outcome of pending or future litigation; and the various risks and uncertainties described in the "Risk Factors" sections of our latest annual and quarterly reports and other filings with the SEC.

All forward-looking statements are expressly qualified in their entirety by this cautionary notice. You should not rely upon any forward-looking statements as predictions of future events. We undertake no obligation to revise or update any forward-looking statements made in this presentation to reflect events or circumstances after the date hereof, to reflect new information or the occurrence of unanticipated events, to update the reasons why actual results could differ materially from those anticipated in the forward-looking statements, in each case, except as required by law.

References

1. Di Fusco, M., Shea, K. M., Lin, J., Nguyen, J. L., Angulo, F. J., Benigno, M., Malhotra, D., Emir, B., Sung, A. H., Hammond, J. L., Stoychev, S., & Charos, A. (2021). Health Outcomes and economic burden of hospitalized COVID-19 patients in the United States. Journal of Medical Economics, 24(1), 308–317. https://doi.org/10.1080/13696998.2021.1886109

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Humanigen Investor Relations

Ken Trbovich

Humanigen

trbo@humanigen.com

650-410-3206

Source: Humanigen, Inc.