CHICAGO, Illinois and SAN CARLOS, California — May 27, 2026
BeOne Medicines announced new clinical findings from the Phase 3 HERIZON-GEA-01 study published in The New England Journal of Medicine (NEJM) and presented during an oral session at the American Society of Clinical Oncology (ASCO) 2026 Annual Meeting. The study evaluated ZIIHERA® (zanidatamab) plus chemotherapy, with and without TEVIMBRA® (tislelizumab), as first-line treatment for patients with advanced or metastatic HER2-positive gastroesophageal adenocarcinoma (GEA). Results showed that the triplet combination of TEVIMBRA, ZIIHERA, and chemotherapy achieved statistically significant improvements in overall survival, progression-free survival, and duration of response compared with trastuzumab plus chemotherapy.
HERIZON-GEA-01 Demonstrates Significant Overall Survival Benefit
The Phase 3 HERIZON-GEA-01 trial enrolled 914 patients across more than 30 countries and compared three treatment regimens in previously untreated HER2-positive gastroesophageal adenocarcinoma. Patients receiving the combination of TEVIMBRA plus ZIIHERA and chemotherapy achieved a median overall survival of 26.4 months, compared with 19.2 months in the trastuzumab plus chemotherapy control arm. The ZIIHERA plus chemotherapy arm demonstrated a median overall survival of 24.4 months.
Investigators also reported a median progression-free survival of 12.4 months in both ZIIHERA-containing treatment arms. The triplet regimen delivered a median duration of response of 20.7 months, substantially longer than the 8.3 months observed in the control group. Researchers noted that the treatment benefit was observed regardless of PD-L1 expression status, including in patients with PD-L1-negative tumors.
Additional subgroup analyses presented at ASCO 2026 showed that patients with PD-L1 TAP <1% treated with the TEVIMBRA-containing regimen achieved a median overall survival of 29.7 months, compared with 15.8 months in the control arm. In PD-L1-positive patients, median overall survival reached 26.4 months versus 21.2 months with standard therapy.
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Safety Profile and Clinical Implications
Safety findings from the HERIZON-GEA-01 study were generally consistent with the known profiles of HER2-targeted therapy and immunotherapy. The most common Grade 3 or higher treatment-related adverse event was diarrhea, occurring in 24.5% of patients receiving TEVIMBRA plus ZIIHERA and chemotherapy, compared with 12.9% in the control arm. Most diarrhea events occurred early during treatment, and discontinuation rates due to diarrhea remained relatively low after the introduction of mandatory anti-diarrheal prophylaxis during the first cycle.
According to study investigators, the results position the combination of zanidatamab, tislelizumab, and chemotherapy as a potential new standard-of-care option for untreated HER2-positive gastroesophageal adenocarcinoma patients. Researchers emphasized that the survival improvements observed in both PD-L1-positive and PD-L1-negative populations address a significant unmet clinical need in this aggressive cancer type.
Regulatory Progress for TEVIMBRA and ZIIHERA
Following the positive Phase 3 results, the U.S. Food and Drug Administration (FDA) accepted a supplemental Biologics License Application (sBLA) for TEVIMBRA and granted the application priority review. Regulatory submissions for both TEVIMBRA and ZIIHERA have also been accepted by China’s National Medical Products Administration (NMPA) for first-line treatment of advanced or metastatic HER2-positive gastroesophageal adenocarcinoma.
HER2-positive gastroesophageal adenocarcinoma represents approximately 20% of gastroesophageal cancer cases worldwide and remains associated with poor long-term survival outcomes. Investigators believe the HERIZON-GEA-01 study provides strong evidence supporting dual HER2-targeted and PD-1-directed treatment approaches in frontline metastatic disease management.
Source: BeOne Medicines press release
