Zymeworks announces updated data for HER2-Targeted Bispecific Antibody ZW25
Zymeworks announced updated data from the ongoing multi-center Phase 1 clinical trial evaluating ZW25 in patients with HER2-expressing solid tumors, including biliary tract cancer, colorectal cancer, gynecological cancers, and gastroesophageal adenocarcinoma, in a poster discussion presentation at the ESMO 2019 Congress. Based on the data from the ongoing Phase 1 study, Zymeworks has initiated a broad clinical development program for ZW25 in multiple HER2-expressing cancers. In addition to the Phase 2 BTC trial announced, Zymeworks is continuing to evaluate ZW25 as a potential treatment for patients with other HER2-expressing cancers, including CRC and gynecological cancers. For patients with HER2-expressing GEA, ZW25 is being developed as a first-line treatment in combination with standard of care chemotherapy. Zymeworks also plans to initiate a Phase 2 study of ZW25 in combination with a CDK4/6 inhibitor and hormone therapy in third-line HER2-expressing, HR-positive breast cancer. Data were reported from 58 patients diagnosed with HER2-expressing solid tumors other than breast cancer who received ZW25 at the recommended dose of either 10 mg/kg weekly or 20 mg/kg every other week. Patients had a median age of 61 years and received a median of four prior therapies. 32 patients received prior HER2-targeted therapies including 87% of GEA patients. Of all patients, 23 were diagnosed with GEA, 13 with CRC, nine with BTC, and 13 with other HER2-expressing cancers, including endometrial, ovarian, pancreatic, and salivary gland. At the time of data cut-off, 46 of 58 patients were response evaluable. Overall, the majority of patients experienced a decrease in their target lesions with a disease control rate of 72%, comprising 16 patients with partial responses and 17 with stable disease. The objective response rate in the six evaluable biliary tract cancer patients was 67%, with the majority of patients experiencing disease control greater than six months. In the 11 CRC and 19 GEA patients, the objective response rates were 36% and 32%, respectively. The overall median progression-free survival was 5.2 months, with 27 of the 58 total patients still on study at the time of data cut-off. Among all patients, ZW25 was well tolerated as an outpatient therapy. All treatment-related adverse events occurring in 10% or more of patients were Grade 1 or 2.