Humanigen Announces Lenzilumab Study Results Accepted as Oral Presentation at the 2018 Annual Meeting of the American Society of Hematology (ASH)

Study Demonstrates that GM-CSF Neutralization with Lenzilumab in Combination with Chimeric Antigen Receptor T (CAR-T) Cell Therapy Prevents the Onset of Cytokine Release Syndrome, Significantly Reduces the Severity of Neurotoxicity and Improves CAR-T Proliferation and Effector Functions

BURLINGAME, Calif., Nov. 02, 2018 (GLOBE NEWSWIRE) -- Humanigen, Inc., (OTCQB: HGEN) ("Humanigen"), a biopharmaceutical company developing its portfolio of Humaneered^® monoclonal antibodies to address cutting-edge CAR-T optimization and oncology treatments, today announced that final results from a preclinical study demonstrating that use of the Company's proprietary, anti-GM-CSF monoclonal antibody, lenzilumab, in combination with CD19 targeted chimeric antigen receptor T (CART19) cell therapy prevents cytokine release syndrome (CRS), significantly reduces neurotoxicity (NT) and enhances CART19 proliferation and effector functions have been accepted as an oral presentation at the 2018 Annual Meeting of the American Society of Hematology (ASH).  

The study, led by Rosalie M. Sterner and Saad S. Kenderian at Mayo Clinic in Rochester, MN, utilized a novel xenograft model derived from patients with high risk, relapsed acute lymphoblastic leukemia (ALL) treated with patient-derived CART19.  This xenograft model was designed to recapitulate the findings that have been reported in CART19 clinical trials in patients with severe CRS and NT.  In this model, five days after CART19 treatment, animals began to develop progressive motor weakness, hunched bodies, and weight loss that correlated with massive elevation of circulating human cytokine levels. Magnetic Resonance Imaging (MRI) of the brain during this syndrome showed diffuse enhancement and edema, associated with central nervous system (CNS) infiltration of CART cells and murine activated myeloid cells similar to findings seen in patients with severe NT. MRI with volumetric analysis was used to characterize and quantify the neuro-inflammation associated with CART19 therapy with and without lenzilumab. 

The proprietary xenograft model was designed using:

• Human tumor blasts (ALL)
• Human CD19 CAR-T
• Human Peripheral Blood Mononuclear Cells (PBMCs)

Compared to CART19 plus control antibody, the combination of lenzilumab plus CART19 resulted in:

• a significant reduction in neuro-inflammation and cerebral edema as measured by quantitative MRI
• prevention of CRS-induced emaciation, weakness, and weight loss
• a significant reduction in GM-CSF and other downstream pro-inflammatory cytokines and chemokines associated with and predictive of NT and CRS including MCP-1/CCL2
• an exponential increase in CAR-T cell proliferation
• a reduction in myeloid cell infiltration into the CNS
• enhanced central nervous system (CNS) leukemic disease control

The full abstract with corresponding figures is available for review at https://ash.confex.com/ash/2018/webprogram/Paper111766.html

The oral presentation will include updated data not available in the abstract and the complete data set will be presented in the oral plenary session at the 2018 Annual Meeting of the American Society of Hematology, at 4:30pm PT on Monday, December 3^rd, 2018 at the Marriott Marquis San Diego Marina, San Diego Ballroom B.  "This is the only clinical stage asset that has been demonstrated in vivo to improve both the safety and efficacy of CART19," said Dr. Cameron Durrant, chief executive officer of Humanigen.  "CRS and NT are associated with extended hospitalization and ICU admissions, which creates an added pharmaco-economic burden that limits the utility and uptake of CAR-T cell therapy.  We are committed to developing lenzilumab to help CAR-T cell therapy realize its full potential."

About Humanigen, Inc. 

Humanigen, Inc. is developing its portfolio of Humaneered^® monoclonal antibodies to address cutting-edge CAR-T optimization and oncology treatments advancing safer, better, and more effective cancer therapies. 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 biologic therapy 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 the Eph type-A receptor 3 (EphA3), is being explored as a potential treatment for glioblastoma multiforme (GBM) and other deadly cancers, both as naked antibody and as part of an antibody-drug conjugate, as well as a backbone for a novel CAR-T construct, and a 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 future development of lenzilumab to help CAR-T therapy reach its full potential. 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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