Jazz Pharmaceuticals, Zymeworks report 84% survival for zanidatamab in mGEA

Jazz Pharmaceuticals (JAZZ) and Zymeworks (ZYME) today announced tolerability and efficacy results, including the first overall survival (OS) data, from a Phase 2 trial examining zanidatamab, an investigational HER2-targeted bispecific antibody, in combination with chemotherapy, in first-line patients with HER2-expressing metastatic gastroesophageal adenocarcinoma, or mGEA. Preliminary results showed that median OS had not yet been reached with a median duration of study follow-up of 26.5 months. The 18-month overall survival rate was 84%. The data demonstrated zanidatamab combined with standard chemotherapy is a highly active treatment regimen for first-line therapy of HER2-positive mGEA. 18-month OS rate was 84%, 12-month OS rate was 88%, and the median overall survival had not yet been reached. Treatment with zanidatamab resulted in a confirmed objective response rate of 79%, a disease control rate of 92%, with three patients achieving complete response among 38 response-evaluable patients. The median duration of response was 20.4 months with a median progression-free survival of 12.5 months. The regimen was manageable, tolerable and consistent with the observed safety profiles reported for other standard combination regimens for patients with HER2-positive GEA. Zymeworks continues to enroll patients in the Phase 3 randomized clinical trial evaluating zanidatamab in combination with chemotherapy plus or minus tislelizumab as a first-line treatment for HER2-expressing mGEA.