Ziihera (zanidatamab-hrii) - (HERIZON-GEA-01)

August 6, 2026: Zymeworks (NASDAQ: ZYME) highlighted multiple 2H 2026 catalysts. For zanidatamab (Ziihera), the U.S. PDUFA target action date is August 25, 2026 for first-line HER2-positive locally advanced or metastatic gastroesophageal adenocarcinoma; approval could trigger a $250 million U.S. milestone and is the first of up to $440 million in global regulatory milestones. The company said top-line results from the second interim overall survival analysis of the HERIZON-GEA-01 doublet regimen are expected in Q3 2026. FDA also granted Breakthrough Therapy Designation for zanidatamab in previously treated unresectable/metastatic HER2-positive colorectal cancer. EmpowHER-303 enrollment is expected to complete in mid-2027, with top-line data by end-2027 or early 2028.

For pasritamig, Johnson & Johnson plans to present Phase 1b combination data in advanced prostate cancer in 2H 2026. Its Phase 3 trial in late-line mCRPC increased planned enrollment from about 663 to 1,203 patients; primary completion is now estimated for December 2027.

For ZW191, Phase 1 dose-escalation data presented in June 2026 showed cORR of 78.6% in FRα-positive and 47.4% in FRα-negative platinum-resistant ovarian cancer patients. ZW251 Phase 1b enrollment is ongoing.

Separately, Zymeworks expects its Theravance Biopharma acquisition to close in 2H 2026.