Ambrx announced that the US Food and Drug Administration (FDA) granted ARX788 Fast Track Designation as monotherapy for the treatment of advanced or metastatic HER2-positive breast cancer patients who have received one or more prior anti-HER2 based regimens in the metastatic setting.

“This is an important milestone for ARX788 that underscores the strong unmet medical need to develop new and effective treatment options for breast cancer patients whose tumors progressed on currently approved HER2 directed regimens,” said Joy Yan, MD, PhD, Ambrx Chief Medical Officer. “It’s our mission to drive science forward to help bring innovative therapeutic options to cancer patients and we look forward to working closely with the FDA to optimize and expedite the development of ARX788.”  This designation was granted based on the phase 1 studies that assessed the safety, tolerability, pharmacokinetic (PK), and preliminary efficacy of ARX788.

ARX788 is a homogeneous and highly stable antibody drug conjugate (ADC) targeting the HER2 receptor. ARX788 is a Precision Biologic ADC that consists of two cytotoxic payloads site-specifically conjugated to a Herceptin? (trastuzumab) based antibody. ARX788 was designed for maximum performance in the preclinical setting by optimizing the number, position and chemical bonds that conjugate the cytotoxic AS269 payload to the antibody. AS269 is a proprietary tubulin inhibitor specifically designed to form a highly stable covalent bond with our synthetic amino acids, a fundamental step in the creation of a Precision ADC. Ambrx licensed the China rights of ARX788 to its partner NovoCodex.

Human epidermal growth factor receptor 2 (HER2) is a tyrosine kinase receptor growth-promoting protein found on the surface of some cancer cells. About 20% of breast cancers overexpress the HER2/neu gene, which causes these cancers to grow more aggressively.  Unmet medical needs remain today in HER2-positive metastatic breast cancer. Many tumors progressed after currently approved HER2-targeted regimens.

Ambrx is a clinical stage biopharmaceutical company using an expanded genetic code to create Precision Biologics, this includes next generation antibody drug conjugates (ADCs), bispecifics, and targeted immuno-oncology therapies for cancer as well as novel cytokines to modulate the immune system and long-acting therapeutic peptides for metabolic and cardiovascular disease, all designed to have improved pharmacologic properties and novel biological activity.