Zymeworks Inc. presented preliminary results from the company's Phase 1 clinical trial evaluating zanidatamab zovodotin (ZW49) for the treatment of HER2-positive tumors. The presentation, entitled “Preliminary Results From a Phase 1 Study Using the Bispecific, Human Epidermal Growth Factor 2 (HER2)-targeting Antibody-drug Conjugate (ADC) zanidatamab zovodotin (ZW49) in Solid Cancers”, was presented by Komal Jhaveri, MD, FACP, medical oncologist, Memorial Sloan Kettering Cancer Center in NYC, in a mini-oral presentation during the European Society for Medical Oncology Annual Congress at the Paris Expo Porte de Versailles in Paris, France. A total of 77 patients were enrolled in this first-in-human trial, which was designed to determine the maximum tolerated dose of zanidatamab zovodotin, characterize its safety and tolerability, and evaluate anti-tumor activity in HER2-expressing cancers as monotherapy.

The patients represented a variety of HER2-expressing cancers including breast, gastroesophageal, ovarian, endometrial, bladder, biliary tract, anal, colorectal, pancreatic and lung. At the time of the analysis, the maximum tolerated dose had not yet been reached. In the trial, zanidatamab zovodotin was shown to have a manageable safety profile with the majority of adverse events being Grade 1 or 2 in severity.

In patients with HER2-positive cancers treated with zanidatamab zovodotin at 2.5 mg/kg Q3W (dose escalation + dose expansion), the confirmed objective response rate was 31% and the disease control rate was 72%. The Phase 1 clinical trial is ongoing and continues to enroll patients to study safety, tolerability and activity for an alternate qW dosing regimen. The Company expects to present results of this dosing regimen at a medical meeting in 2023.