September 2, 2025 — Leads & Copy — Zymeworks Inc. (Nasdaq: ZYME) has decided to discontinue clinical development of ZW171, a T cell engager targeting gynecological, thoracic, and digestive system cancers. The decision follows the completion of planned cohorts in a Phase 1 trial involving patients with ovarian cancer and non-small cell lung cancer.
The company determined that further dose evaluation wouldn’t likely support a benefit-risk profile consistent with its monotherapy target. Although cytokine release syndrome was managed, dose-limiting toxicities were consistent with mesothelin-related on-target off-tumor toxicity. Ongoing participants will continue treatment at the discretion of their investigator, while those who have discontinued will continue safety follow-up.
Kenneth Galbraith, Chair and CEO of Zymeworks, expressed gratitude to patients, providers, and caregivers involved in the ZW171 Phase 1 study. The company will advance its broader product pipeline, including trials for ZW191 and ZW251, and prepare an IND filing for ZW209.
Zymeworks is a clinical-stage biotechnology company focused on developing multifunctional biotherapeutics for conditions like cancer, inflammation, and autoimmune disease. Zanidatamab, a HER2-targeted bispecific antibody, has received approvals in the U.S., China, and Europe for treating HER2-positive biliary tract cancer.
Investor inquiries:
Shrinal Inamdar
Senior Director, Investor Relations
(604) 678-1388
ir@zymeworks.com
Media inquiries:
Diana Papove
Senior Director, Corporate Communications
(604) 678-1388
media@zymeworks.com
Source: Zymeworks Inc.
