Zanidatamab Plus Chemotherapy Prolongs PFS Over Trastuzumab Plus Chemotherapy in Patients with HER2-positive Advanced Gastro-Oesophageal Adenocarcinoma

Headline: Phase 3 HERIZON‑GEA‑01 — zanidatamab chemo improves PFS vs trastuzumab chemo in HER2‑positive advanced gastro‑oesophageal adenocarcinoma Summary: The phase 3 HERIZON‑GEA‑01 readout, published in NEJM ahead of ASCO 2026 and covered by ESMO and company communications, shows zanidatamab plus chemotherapy prolongs progression‑free survival compared with the long‑standing comparator trastuzumab plus chemotherapy in HER2‑positive advanced gastro‑oesophageal adenocarcinoma. The trial also tested adding the anti‑PD‑1 tislelizumab, but clinicians (including Kohei Shitara and Nikhil Vasudeva) are debating whether that addition meaningfully changes outcomes. Overall, the data are an encouraging, if incremental, advance for a difficult‑to‑treat disease (sources: Jazz Pharmaceuticals/press coverage, NEJM/ASCO posts, ESMO summary, OncoDaily discussion).