Zymeworks Announces Decision to Discontinue Clinical Development of ZW171, a Mesothelin-directed T cell Engager

Core Viewpoint - Zymeworks Inc. has decided to voluntarily discontinue the clinical development of ZW171, a T cell engager targeting specific cancers, after evaluating the results from the Phase 1 trial, which indicated that further development would not support a favorable benefit-risk profile [1][3][4]. Company Overview - Zymeworks Inc. is a clinical-stage biotechnology company focused on developing novel biotherapeutics for difficult-to-treat diseases, including cancer, inflammation, and autoimmune diseases [1][5]. - The company utilizes proprietary technologies, such as Azymetric™, to engineer and develop differentiated antibody-based therapeutic candidates [5]. Clinical Development Update - The decision to halt ZW171's development was based on the completion of planned cohorts in the Phase 1 trial, where a maximum tolerated dose was established, but dose-limiting toxicities were observed [3]. - Ongoing participants in the trial will continue treatment at the discretion of their investigators, while those who have discontinued will undergo safety follow-up as per the study protocol [3]. Future Pipeline - Despite the setback with ZW171, Zymeworks is advancing its broader product pipeline, including the ongoing Phase 1 trial of ZW191 and the expected initiation of a Phase 1 study for ZW251 in 2025 [4]. - The company is also preparing an IND filing for ZW209, a DLL3-directed trispecific T cell engager, planned for the first half of 2026 [4]. Product Achievements - Zymeworks has developed zanidatamab, a HER2-targeted bispecific antibody, which has received accelerated approval from the U.S. FDA and conditional approvals in China and Europe for treating specific cancer types [5]. - Zanidatamab is being evaluated in multiple global clinical trials as a potential best-in-class treatment for various HER2-expressing cancers [5]. Strategic Partnerships - The company has entered into agreements with BeOne Medicines Ltd. and Jazz Pharmaceuticals, granting them exclusive rights to develop and commercialize zanidatamab in different territories [5].