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BeiGene, Zymeworks Dose First Patient in Phase IB/II Trial for HER2-Positive Cancers

NEW YORK – On Wednesday, BeiGene said that it has dosed the first patient in its two-arm Phase IB/II trial of a drug combination to treat metastatic breast cancer and metastatic gastroesophageal adenocarcinoma (GEA) patients.

One arm of the study is evaluating Zymeworks' HER2-targeted bispecific antibody ZW25 in combination with the chemotherapy docetaxel as a first-line treatment for HER2-positive metastatic breast cancer patients, and the other arm is evaluating ZW25 in combination with chemotherapy and BeiGene's PD-1-targeted antibody tislelizumab as a first-line treatment for HER2-positive metastatic GEA. 

The trial will enroll up to 50 participants and track efficacy, safety, tolerability, and objective response rate as the primary endpoints.

Under a 2018 agreement between BeiGene and Zymeworks, BeiGene has an exclusive license for the research, development and commercialization of ZW25 and HER2-targeted antibody drug conjugate ZW49 in Asia (excluding Japan), Australia, and New Zealand. Zymeworks will receive a milestone payment from BeiGene as a result of the achievement of this new development milestone of the study starting enrollment.

The companies also plan to initiate registration-enabling studies of ZW25 in patients with previously treated HER2-positive biliary tract cancer and develop ZW25 as a potential first-line treatment for patients with HER2-positive GEA.

Zymeworks is developing ZW25 as a targeted treatment option for patients with HER2-expressing solid tumors. The US Food and Drug Administration has granted two fast track designations to ZW25, one as a single agent for refractory biliary tract cancer and one in combination with standard of care chemotherapy for first-line GEA.

"To date, ZW25 has demonstrated promising activity in late-stage, treatment-refractory HER2‑expressing tumors. This new clinical trial provides a unique opportunity to evaluate the additional potential benefit of ZW25 in first-line metastatic breast tumors, which have not developed resistance to multiple HER2-targeted therapeutics," Zymeworks CMO Diana Hausman said in a statement.

ZW25 is also being studied in a number of other trials, including in combination with the oral CDK4/6 inhibitor palbociclib (Pfizer's Ibrance) and fulvestrant in advanced HER2‑positive, hormone receptor‑positive breast cancer.