Humanigen Announces Preclinical Findings Presented on Lenzilumab’s Potential to Optimize CAR-T Therapy

Lenzilumab effectively neutralizes GM-CSF

CAR-T cells maintained robust anti-tumor activity in combination with lenzilumab

GM-CSF depletion by lenzilumab may increase CAR-T expansion

BRISBANE, Calif., May 02, 2018 --  Humanigen, Inc. (OTCQB:HGEN), a biopharmaceutical company developing cutting-edge CAR-T optimization and oncology treatments, today announced that preclinical findings on lenzilumab’s potential as a new strategy to increase the safety and efficacy of chimeric antigen receptor T-cell (CAR-T) therapy were presented at The Essential Protein Engineering Summit (PEGS) Dr. Saad Kenderian, director, T cell engineering program at Mayo Clinic.

Lenzilumab is a first-in-class Humaneered^® recombinant monoclonal antibody that targets and is an antagonist of soluble granulocyte-macrophage colony-stimulating factor (GM-CSF). Neutralization of circulating GM-CSF has the potential to blunt or prevent an inflammatory cascade that can result in serious and life-threatening CAR-T-induced side effects – neurotoxicity and Cytokine Release Syndrome – and possibly boost efficacy of CAR-T therapy. Improved treatment response could come through increased expansion of CAR-T, as seen in the ZUMA-1 pivotal trial.

The PEGS presentation on May 1 highlighted findings from preclinical studies using validated animal models. The key findings included:

• Lenzilumab effectively neutralizes GM-CSF.
• Lenzilumab does not inhibit CAR-T efficacy in vivo, as CAR-T plus lenzilumab exhibited an improved rate of survival compared to a control in the same mouse xenograft model.
• GM-CSF depletion by lenzilumab may increase CAR-T expansion in vivo, as a more robust proliferation was observed after adding lenzilumab.

“There’s significant need for new science to find therapeutic combinations to improve the safety and efficacy of CAR-T therapy. These encouraging findings reinforce our belief that lenzilumab has the potential to make CAR-T safer, better and more routine in the treatment of cancer,” said Cameron Durrant, M.D., chairman and chief executive officer of Humanigen. “We look forward to starting clinical work soon with the goal of improving this groundbreaking treatment for patients.”

The company anticipates commencing a potentially pivotal phase I/II trial of lenzilumab as a prophylactic therapy prior to CAR-T infusion to optimize treatment and minimize or prevent neurotoxicity associated with CAR-T cancer therapy in the summer of 2018.

About Lenzilumab

Lenzilumab is a first-in-class, novel Humaneered^® recombinant monoclonal antibody designed to target and neutralize circulating granulocyte-macrophage colony-stimulating factor (GM-CSF), the myeloid inflammation factor involved in the recruitment of myeloid cells to a tumor and a central actor in leukocyte differentiation, autoimmunity and inflammation. There is also extensive evidence linking GM-CSF expression to serious and potentially life-threatening side effects in chimeric antigen receptor T-cell (CAR-T) therapy, such as neurotoxicity and Cytokine Release Syndrome (CRS). Humanigen is working with leading CAR-T experts to develop lenzilumab as a potential prophylactic therapy to optimize treatment and minimize or prevent neurotoxicity associated with CAR-T cancer therapy. In addition, lenzilumab is currently being evaluated as a potential treatment for rare leukemias in a phase I trial (NCT02546284) in patients with chronic myelomonocytic leukemia (CMML), with additional potential in juvenile myelomonocytic leukemia (JMML), a rare pediatric cancer. In previous clinical trials, lenzilumab has shown to be safe and well tolerated in more than 100 patients, including those with rheumatoid arthritis, asthma and healthy volunteers. It is a potent inhibitor of GM-CSF in vivo.

About Humanigen 

Humanigen, Inc. is a biopharmaceutical company developing cutting-edge CAR-T optimization and oncology treatments. Derived from the company’s Humaneered^® platform, lenzilumab and ifabotuzumab are monoclonal antibodies with first-in-class mechanisms. Lenzilumab, which targets GM-CSF, is in development as a potential medicine to make CAR-T therapy safer and more effective, as well as a potential treatment for rare hematologic cancers such as CMML and JMML. Ifabotuzumab, which targets Ephrin type-A receptor 3 (EphA3), is being explored as a potential treatment for glioblastoma multiforme (GBM) and other deadly cancers, as well as a backbone for a novel CAR-T construct and bispecific antibody platform. For more information, visit www.humanigen.com.

Forward-Looking Statements

This release contains forward-looking statements that are intended to be subject to protection afforded by the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. 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," "expect," "intend," "plan," "potential," "possible," "goals," "accelerate," "continue," and similar expressions identify forward-looking statements, including, without limitation, statements regarding our expectations for timing of, and executing on, the key priorities and anticipated milestones described above in regard to the phase I/II trial of lenzilumab as a prophylactic therapy prior to CAR-T infusion to optimize treatment and minimize or prevent neurotoxicity associated with CAR-T therapy and the phase I study as a potential treatment for CMML, and the investigator-sponsored phase 0/1 radio-labeled imaging trial of ifabotuzumab as a potential treatment of GBM. Forward-looking statements are subject to a number of risks and uncertainties including, but not limited to, the risks inherent in Black Horse Capital and its affiliates owning more than 50% of our outstanding common stock, including their ability to control the company; our lack of profitability and the need for additional capital to operate our business as a going concern; the uncertainties inherent in the development 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 Company's periodic and other filings with the Securities and Exchange Commission.

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