Athenex Announces US FDA Allowance of IND Application

Athenex, Inc. recently announced that the US FDA has allowed the company’s Investigational New Drug (IND) application for the clinical investigation of PT01 (Pegtomarginase) for the treatment of patients with advanced malignancies. The allowance is contingent upon formal submission of agreed upon updates to the IND. Pegtomarginase is a biologic product candidate in Athenex’s pipeline that is designed to provide a metabolic approach to the treatment of cancer through arginine deprivation therapy.

Pegtomarginase is a PEGylated genetically modified human arginase that targets cancer growth and survival by removing the supply of an amino acid, arginine. A significant proportion of cancer types lack the ability to synthesize arginine due to deficient expression of certain metabolic enzymes of the urea cycle, including argininosuccinate synthetase 1 (ASS1), argininosuccinate lyase (ASL) or ornithine transcarbamylase (OTC). By depleting circulating arginine, growth of cancers with a disrupted urea cycle can be halted and cell death can be induced. Healthy cells capable of producing sufficient arginine would be largely unaffected. Previous arginine depleting therapies employed enzymes that were derived from non-human origin, which can trigger the development of neutralizing antibodies, or had multiple PEGylation sites with multiple positional isomers in the product. Athenex believes that its therapeutic

Pegtomarginase, initially developed by The Hong Kong Polytechnic University (PolyU) and Avalon Biomedical (Management) Limited (Avalon Biomedical), possesses many promising attributes, notably the human-derived origin and recombinant modification that has enabled site-specific PEGylation. The resulting single isomer has a predictable and extended duration of action as demonstrated by durable arginine depletion in preclinical studies.

“We are excited to further explore this innovative approach to treating a broad range of cancers using this biologic product,” stated Dr. Michael Smolinski, Senior Director, Preclinical Operations of Athenex. “We were encouraged by Pegtomarginase’s compelling profile, specifically the defined site-directed PEGylation and the resulting high activity at well-tolerated doses observed in preclinical studies. We are pleased to advance this program into the clinic and believe it offers a step forward for metabolic therapies in oncology.”

Dr. Johnson Lau, Chairman and Chief Executive Officer of Athenex, added, “This will be the Company’s ninth IND candidate allowed by the FDA, demonstrating the strong execution capabilities of our research and development team. Advancing this program is in line with our strategy to expand the types of therapeutic options for cancer patients. We believe Pegtomarginase has significant potential not only as a monotherapy, but also in combination with other oncology therapeutics, including those in Athenex’s pipeline. In addition, we believe this paves the way for the use of metabolic therapeutics to condition the tumor microenvironment in order to enhance the anti-tumor activity of different therapies in combination.”

Ir Professor Alexander Wai, Vice President (Research Development) of PolyU, commented, “We are delighted by this significant milestone achieved for Pegtomarginase, which was initially developed by the research team led by Professors Thomas Leung and Thomas Lo in the Department of Applied Biology and Chemical Technology and Lo Ka Chung Research Center for Natural Anti-Cancer Drug Development at PolyU. We have learned a lot through the collaboration with Avalon Biomedical and Athenex, which has also been extremely rewarding. We are deeply impressed by the strong execution capabilities at Athenex and the team’s commitment to commercializing novel technologies for the treatment of a wide range of cancers.”

Athenex recently presented preclinical study results of Pegtomarginase in a poster session at the 2019 American Society of Clinical Oncology Annual Meeting. The biologic agent demonstrated high enzymatic activity, predictable pharmacokinetic-pharmacodynamic profiles, and cytotoxicity in vitro. Mouse xenograft models showed good tumor growth inhibition activity at tolerable doses with only transient weight loss during therapy.

Athenex licensed the worldwide rights to develop and commercialize Pegtomarginase from Avalon PolyTom (HK) Limited, a subsidiary of Avalon Biomedical. Pegtomarginase was initially developed by PolyU and subsequently licensed to Avalon PolyTom during the initial phase of preclinical development.

Arginine Deprivation Therapy
Arginine is an essential amino acid to many tumor types for survival and growth. Many cancers have deficient expression of certain metabolic enzymes such as argininosuccinate synthetase 1 (ASS1), argininosuccinate lyase (ASL) or ornithine transcarbamylase (OTC), which are needed to synthesize arginine. Such cancers, also known as arginine-auxotrophic cancers, depend on external sources of arginine, making arginine deprivation therapy a potentially viable strategy for tumor treatment.

About Athenex, Inc.
Founded in 2003, Athenex, Inc. is a global clinical stage biopharmaceutical company dedicated to becoming a leader in the discovery, development and commercialization of next generation drugs for the treatment of cancer. Athenex is organized around three platforms, including an Oncology Innovation Platform, a Commercial Platform and a Global Supply Chain Platform. The Company’s current clinical pipeline is derived from four different platform technologies: (1) Orascovery, based on non-absorbed P-glycoprotein inhibitor, (2) Src kinase inhibition, (3) T-cell receptor-engineered T-cells (TCR-T), and (4) Arginine deprivation therapy. Athenex’s employees worldwide are dedicated to improving the lives of cancer patients by creating more active and tolerable treatments.  Athenex has offices in Buffalo and Clarence, New York; Cranford, New Jersey; Houston, Texas; Chicago, Illinois; Hong Kong; Taipei, Taiwan; and multiple locations in Chongqing, China. For more information, visit www.athenex.com.