Zymeworks/BeiGeneZymeworks (NYSE:ZYME) and its collaborator BeiGene have announced the dosing of the first patient with zanidatamab (ZW25) in South Korea–based HERIZON-GEA-01 study. The study will focus on patients with advanced or metastatic HER2-positive gastroesophageal adenocarcinomas.

As a result of the development, Zymeworks will receive an $8 million development milestone payment from BeiGene.

Zymeworks and BeiGene plan to open roughly 300 clinical trial sites in 38 countries for the global HERIZON-GEA-01 pivotal trial. The companies anticipate approximately 700 patients to enroll in the study.

The Phase 3 trial will evaluate zanidatamab with a physician’s choice of chemotherapy (capecitabine/oxaliplatin or 5FU/cisplatin) with or without the PD-1 inhibitor tislelizumab. The study will pit that cohort against a group receiving trastuzumab and a physician’s choice chemotherapy.

Zanidatamab, a bispecific antibody, is one of Zymeworks’ lead drug candidates.

The drug has been the subject of a dozen clinical trials, according to AdisInsight.