Humanigen Announces Positive Results From Phase 1 Study of Ifabotuzumab in Glioblastoma Multiforme

• Phase 1 dose escalation and bioimaging study shows that ifabotuzumab demonstrates highly specific tumor targeting in patients with recurrent glioblastoma multiforme
• Results to be presented as a virtual poster at American Association for Cancer Research (AACR) 2021 Annual Meeting

Humanigen, Inc. (Nasdaq:HGEN), a clinical-stage biopharmaceutical company focused on preventing and treating an immune hyper-response called ‘cytokine storm’ with its lead drug candidate, lenzilumab™, today announced positive results from the Phase 1 safety and bioimaging trial of its second Humaneered® antibody, ifabotuzumab, in patients with glioblastoma multiforme (GBM). In the study, ifabotuzumab demonstrated highly sensitive, specific, and reproducible targeting of the tumor and tumor microenvironment in all patients. The results will be presented as a poster at the AACR Annual Meeting 2021, held virtually from April 10-15, 2021, and remain available until June 21, 2021.

The Phase 1 study primarily sought to determine the safety and recommended Phase 2 dose of ifabotuzumab in patients with GBM, the most frequent and lethal primary brain neoplasm, with 5-year survival rates of 10%. It is estimated there are more than 18,000 deaths from brain cancer annually in the United States.¹ Ifabotuzumab is a non-fucosylated IgG1κ antibody targeting the EphA3 receptor. EphA3 is a tumor-restricted antigen expressed in the tumor vasculature and tumor stroma of various solid tumors including breast, colon, lung, prostate, melanoma, and GBM. The study showed that, at both doses, ifabotuzumab demonstrated highly sensitive, specific, and reproducible targeting of the tumor and tumor microenvironment in all patients. There were no dose-limiting toxicities observed and all adverse events were readily manageable. Additional studies are planned to evaluate ifabotuzumab as an antibody-drug conjugate in solid tumor patients.

“GBM represents an extremely aggressive form of cancer that has historically eluded effective treatment, and we remain committed to investigating ifabotuzumab as a potential new approach to treat this devastating disease as well as other solid tumors,” said Prof. Andrew Scott, Head, Tumor Targeting Laboratory, Olivia Newton-John Cancer Research Institute, Professor, School of Cancer Medicine, La Trobe University, member of the Australian Brain Cancer Mission Strategic Advisory Group, and Principal Investigator of the Phase 1 study. “The positive results of the Phase 1 study, which show ifabotuzumab to be well-tolerated and effective at targeting the EphA3 receptor, support further investigation into ifabotuzumab’s effect on other solid tumors in a Phase 2 study.”

The poster, titled “A phase 1 safety and bioimaging trial of ifabotuzumab (KB004) in patients with glioblastoma,” will be presented virtually at the AACR Annual Meeting during the Phase 1 Clinical Trials Session on Saturday, April 10, 2021. The study was led by Principal Investigator Andrew Scott from the Olivia Newton-John Cancer Research Institute in Australia. Funding was provided by Cure Brain Cancer Foundation, the Queensland Government, Austin Health, and Humanigen.

“We are pleased to announce the positive Phase 1 results of ifabotuzumab in patients with gliobastoma multiforme,” said Cameron Durrant, MD, MBA, Chief Executive Officer of Humanigen. “There is a tremendous need to advance new therapies for solid tumors, and this trial shows that ifabotuzumab demonstrates great potential. Ifabotuzumab represents an important part of Humanigen’s immuno-oncology arsenal as we advance our pipeline to target a wide-range of cancers, and we are proud to present our findings at this year’s AACR Annual Meeting.”

Details for the upcoming event are below:

AACR Annual Meeting 2021

Virtual abstract presentation viewable starting on Friday, April 9, 2021

Register here: https://www.aacr.org/meeting/aacr-annual-meeting-2021/registration/

E-poster presentation

Date: Saturday, April 10, 2021

Link: https://www.aacr.org/meeting/aacr-annual-meeting-2021/

About Humanigen, Inc.

Humanigen, Inc. is developing its portfolio of clinical and pre-clinical therapies for the treatment of cancers and infectious diseases via its novel, cutting-edge GM-CSF neutralization and gene-knockout platforms. Humanigen believes that its GM-CSF neutralization and gene-editing platform technologies have the potential to reduce the inflammatory cascade associated with coronavirus infection. Humanigen’s immediate focus is to prevent or minimize the cytokine release syndrome that precedes severe lung dysfunction and ARDS in serious cases of SARS-CoV-2 infection. Humanigen is also focused on creating next-generation combinatory gene-edited CAR-T therapies using strategies to improve efficacy while employing GM-CSF gene knockout technologies to control toxicity. In addition, Humanigen is developing its own portfolio of proprietary first-in-class EphA3-CAR-T for various solid cancers and EMR1-CAR-T for various eosinophilic disorders. Humanigen is also exploring the effectiveness of its GM-CSF neutralization technologies (either through the use of lenzilumab as a neutralizing antibody or through GM-CSF gene knockout) in combination with other CAR-T, bispecific or natural killer (NK) T cell engaging immunotherapy treatments to break the efficacy/toxicity linkage, including to prevent and/or treat graft-versus-host disease (GvHD) in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Additionally, Humanigen and Kite, a Gilead Company, are evaluating lenzilumab in combination with Yescarta® (axicabtagene ciloleucel) in patients with relapsed or refractory large B-cell lymphoma in a clinical collaboration. For more information, visit www.humanigen.com and follow Humanigen on LinkedIn, Twitter and Facebook.

Humanigen Forward-Looking Statements

This press release contains forward-looking statements. Forward-looking statements reflect management's current knowledge, assumptions, judgment and expectations regarding future performance or events. Although Humanigen 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," "expect," "intend," "plan," "potential," "possible," "goals," "accelerate," "continue," and similar expressions identify forward-looking statements, including, without limitation, statements regarding the use of lenzilumab to treat patients hospitalized with COVID-19, Humanigen’s expectations regarding the timeline to file for and obtain EUA, statements regarding Humanigen’s ability to attain necessary manufacturing support from contract development and manufacturing organizations, the potential for an expanded manufacturing services relationship with Aji-BioPharma, and statements regarding Humanigen’s beliefs relating to any of the other technologies in Humanigen’s current pipeline. These forward-looking statements are subject to a number of risks and uncertainties including, but not limited to, the risks inherent in Humanigen’s lack of profitability and need for additional capital to grow Humanigen’s business; Humanigen’s dependence on partners to further the development of Humanigen’s product candidates; the uncertainties inherent in the development, attainment of the requisite regulatory approvals or authorization for emergency or broader patient use for the product candidate 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 and elsewhere in the Humanigen's periodic and other filings with the Securities and Exchange Commission.

1. https://seer.cancer.gov/statfacts/html/brain.html

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