Zymeworks Receives FDA Breakthrough Therapy Designation for HER2-Targeted Bispecific Antibody Zanidatamab in Patients with Biliary Tract Cancer

Zymeworks Inc. (NYSE: ZYME), a clinical-stage biopharmaceutical company developing multifunctional biotherapeutics, today announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation for zanidatamab in patients with previously-treated HER2 gene-amplified biliary tract cancer (BTC).

The FDA grants Breakthrough Therapy designation to new medicines that are intended to treat a serious condition and where clinical evidence indicates that the drug may demonstrate substantial improvement over available therapy on a clinically significant endpoint. Zanidatamab will now be eligible for Accelerated Approval, Priority Review and Rolling Review, as well as intensive FDA guidance on an efficient drug development program.

“This Breakthrough Therapy designation from the FDA, based on data generated in BTC patients treated in the initial Phase 1 trial, is recognition of the potential of zanidatamab to provide a new approach to cancer treatment,” said Diana Hausman, M.D., Chief Medical Officer at Zymeworks. “This milestone supports our strategy for accelerated approval and will help make zanidatamab available for patients as quickly as possible.”

“BTC is a rare and aggressive cancer,” said James Priour, Senior Vice President, Commercial, at Zymeworks. “Receiving this designation from the FDA is testament to the potential of zanidatamab to be the first HER2-targeting therapy approved for metastatic BTC patients.”

Earlier this year, Zymeworks initiated a global Phase 2b registration-enabling study of single agent zanidatamab in patients with previously treated HER2 gene-amplified BTC. This study, which is currently enrolling patients, is designed to support accelerated approval based on a primary endpoint of objective response rate, and secondary endpoints of duration of response and safety and may enable submission of a Biologics License Application (BLA) as early as 2022.

This Breakthrough Therapy designation was based on an ongoing clinical trial of zanidatamab in patients with locally advanced (unresectable) and/or metastatic HER2-expressing tumors including BTC. Updated clinical data for single agent zanidatamab patients with BTC has been accepted for presentation at the upcoming American Society of Clinical Oncology’s Virtual Gastrointestinal Cancers Symposium (ASCO GI) January 15-17, 2021.