ASCO

ASCO GI 2026: Zanidatamab combo sets new benchmark in HER2-positive gastroesophageal cancer

January 16, 2026

Results from the phase 3 HERIZON‑GEA‑01 trial (NCT05152147), presented at the 2026 ASCO GI Cancers Symposium, show that zanidatamab plus chemotherapy—with or without tislelizumab—slows disease progression and may improve survival for patients with HER2‑positive metastatic or unresectable gastroesophageal adenocarcinoma.

The study enrolled 914 previously untreated patients and randomized them to zanidatamab + chemotherapy ± tislelizumab or trastuzumab + chemotherapy. After a median 26‑month follow‑up, median progression‑free survival was 12.4 months with zanidatamab‑based therapy vs. 8.1 months with trastuzumab. Zanidatamab reduced the risk of progression or death by 35%. At 18 months, disease remained controlled in 44% of patients receiving the triple combination, 38% on zanidatamab + chemotherapy, and 21% on trastuzumab. Median overall survival (OS) reached 26.4 months with the triple regimen, with a positive trend seen for zanidatamab + chemotherapy.

Grade ≥3 adverse events occurred in 72% of patients on the triple regimen vs. 59% in the other groups. Diarrhea, anemia, and hypokalemia were the most common severe events in zanidatamab groups.

An additional OS analysis is planned for mid‑2026.

Source:

(2026, January 6). ASCO. Zanidatamab and Chemotherapy Can Slow Cancer Growth, Extend Survival in Some People With Gastroesophageal Adenocarcinoma [News release]. https://www.asco.org/about-asco/press-center/news-releases/zanidatamab-and-chemotherapy-can-slow-cancer-growth