Zymeworks announced that its partner, BeiGene has dosed the first patient in a two-arm Phase 1b/2 trial evaluating the former's HER2-targeted bispecific antibody ZW25 in combination with chemotherapy as a first-line treatment for patients with metastatic HER2-positive breast cancer and in combination with chemotherapy and BeiGene’s PD-1-targeted antibody tislelizumab as a first-line treatment for patients with metastatic HER2-positive gastroesophageal adenocarcinoma (GEA).
Zymeworks will receive a payment under its collaboration with BeiGene as a result of the achievement of this development milestone.
“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,” said Diana Hausman, M.D., Chief Medical Officer at Zymeworks. “In addition, the GEA arm of this trial complements our ongoing Phase 2 trial of ZW25 plus chemotherapy in first-line GEA, and we are excited to examine possible synergies between ZW25 and BeiGene’s PD-1 inhibitor tislelizumab. We look forward to the results of these trials, which have the potential to further expand the population of patients who may benefit from ZW25.”
“Through this collaboration with Zymeworks, our broad development program for tislelizumab is expanding into HER2-expressing tumors as a potential first-line treatment,” said Lai Wang, Ph.D., Senior Vice President, Head of Global Research and APAC Clinical Development at BeiGene. “ZW25 has demonstrated appealing clinical activity against HER2-positive tumors, and we are excited to gain additional understanding of its use as a monotherapy and in combinations as well.”
This Phase 1b/2 clinical trial is a multicenter, open-label, two-arm study (NCT04276493). Arm one of the trial will evaluate the safety, tolerability, and preliminary antitumor activity of ZW25 in combination with docetaxel in patients with metastatic HER2‑positive breast cancer. The second arm of the trial will evaluate the safety, tolerability, and preliminary antitumor activity of ZW25 in combination with tislelizumab and chemotherapy in patients with HER2-positive GEA, including gastric and gastroesophageal junction (GEJ) adenocarcinomas.
An ongoing Phase 1 trial is evaluating the safety and antitumor activity of ZW25 as a single agent and in combination with chemotherapy in HER2‑expressing cancers that have progressed after prior standard of care treatments, including HER2-targeted agents (Phase 1: NCT02892123). ZW25 is also being evaluated in a Phase 2 trial in first-line HER2-positive GEA in combination with standard of care chemotherapy (Phase 2: NCT03929666) as well as in combination with the oral CDK4/6 inhibitor palbociclib (Ibrance, Pfizer) and fulvestrant in advanced HER2‑positive, HR‑positive breast cancer (Phase 2: NCT04224272). Zymeworks, in collaboration with BeiGene, also plans 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.
