BeOne's Phase 3 HERIZON-GEA Study Published in NEJM, Slated for Oral Presentation at 2026 ASCO Annual Meeting

SAN CARLOS, May 28, 2026 — Patients living with advanced HER2-positive gastroesophageal adenocarcinoma now have a promising new treatment option. A landmark late-stage clinical trial led by BeOne has yielded impressive survival outcomes across diverse patient groups, with findings formally published in The New England Journal of Medicine (NEJM). The full data will also be showcased via a rapid oral presentation at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago on June 1.

BeOne Medicines Ltd., a global innovative oncology company, conducted the pivotal HERIZON-GEA-01 study. The trial evaluated zanidatamab (Ziihera®) used alone or combined with tislelizumab (Tevimbra®) plus chemotherapy, comparing it against trastuzumab combined with chemotherapy as first-line therapy for patients with advanced or metastatic HER2-positive gastric, gastroesophageal junction and esophageal adenocarcinoma (GEA).

The three-drug regimen consisting of zanidatamab, tislelizumab and chemotherapy brought statistically significant and clinically meaningful overall survival gains. It extended patients'median survival by seven months relative to the control group. Updated analyses for the upcoming ASCO meeting confirmed treatment benefits existed across all subgroups, including patients with PD-L1 expression below 1%.

“The publication of the HERIZON-GEA trial in NEJM underscores the transformative clinical value of zanidatamab-based regimens, which are poised to redefine the first-line standard of care for HER2-positive gastroesophageal adenocarcinoma,” said Dr. Lin Shen, Senior Author and Co-Corresponding Author of the NEJM paper, and Director of the Department of Gastrointestinal Oncology at Peking University Cancer Hospital, as well as a global principal investigator of the HERIZON-GEA-01 trial.

"The robust survival benefits and durable disease control observed with the combination of zanidatamab, tislelizumab and chemotherapy suggest a synergistic anti-tumor effect when adding PD-1 immune checkpoint inhibition to HER2-targeted therapy and chemotherapy," Dr. Shen added. "This breakthrough will bring new treatment hope for HER2-positive GEA patients across China and worldwide."

Primary endpoint and key secondary endpoint results from the Phase 3 trial validated superior clinical outcomes for zanidatamab-containing regimens versus the trastuzumab control regimen:

Overall Survival (OS): The triple combination of zanidatamab, tislelizumab and chemotherapy achieved a median OS of 26.4 months. The dual regimen of zanidatamab plus chemotherapy yielded a median OS of 24.4 months, compared with 19.2 months in the control group.

Progression-Free Survival (PFS): Both zanidatamab treatment arms delivered statistically significant and clinically meaningful PFS improvements, with a consistent median PFS of 12.4 months across both combination regimens.

Duration of Response (DoR): The triple combination arm demonstrated a median DoR of 20.7 months, while the zanidatamab-plus-chemotherapy arm posted a median DoR of 14.3 months, compared with just 8.3 months in the control group.

Dr. Sun Young Rha, Senior Author of the NEJM publication and First Author of the ASCO abstract, from the Division of Medical Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, emphasized the trial’s broad clinical applicability.

"These NEJM-published findings and upcoming ASCO oral presentation data validate that adding tislelizumab to zanidatamab and chemotherapy substantially improves clinical outcomes for HER2-positive GEA patients," Dr. Rha said. "Critically, survival benefits were observed regardless of patients' PD-L1 status, including those with PD-L1 expression <1%. This novel combination represents a promising new treatment option for an area with significant unmet medical need."

Updated subgroup data to be presented at ASCO further confirmed that the zanidatamab-tislelizumab-chemotherapy regimen delivered meaningful PFS and OS improvements for all patients after 26 months of follow-up, with consistent results measured by both Tumor Area Positivity (TAP) and Combined Positive Score (CPS) PD-L1 assessment methodologies.

For patients with PD-L1 TAP <1%, the triple combination regimen achieved an 18-month PFS rate of 50.3% and a 24-month OS rate of 63.7%. For patients with PD-L1 TAP ≥1%, the corresponding 18-month PFS rate was 42.6% and the 24-month OS rate was 53.5%.

The survival advantage was particularly pronounced in PD-L1-negative patients: the triple combination arm delivered a striking median OS of 29.7 months, more than double the control arm's 15.8 months. For PD-L1-positive (TAP ≥1%) patients, the regimen improved median OS to 26.4 months, versus 21.2 months in the control group.

In terms of disease progression control, patients with PD-L1 TAP <1% attained a median PFS of 18.5 months with the triple regimen, compared with 7.9 months for controls. For PD-L1 TAP ≥1% patients, median PFS reached 11.3 months, versus 8.3 months in the control arm.

"With a median OS exceeding 26 months for the triple combination cohort, the HERIZON-GEA-01 trial delivers practice-changing clinical evidence for frontline GEA treatment," a senior BeOne clinical research leader commented. "The comprehensive subgroup data solidifies the survival contribution of tislelizumab, verifying the regimen’s broad efficacy across diverse patient populations."

Safety findings from the triple combination trial aligned with the established safety profiles of HER2-targeted therapy and PD-1 immune checkpoint therapy, with no novel adverse safety signals identified across treatment arms.

Diarrhea was the most common Grade ≥3 treatment-related adverse event (TRAE), occurring in 24.5% of patients in the zanidatamab-tislelizumab-chemotherapy arm, 20.0% of those in the zanidatamab-chemotherapy arm, and 12.9% of patients in the control arm.

Notably, the triple combination arm supported the longest median treatment duration at 43.1 weeks, compared with 31.0 weeks for the dual zanidatamab arm and 30.0 weeks for the control group. Mandatory diarrhea prophylaxis administered during the first treatment cycle effectively mitigated risks, resulting in low treatment discontinuation rates due to drug-related diarrhea: 4.1% in the triple combination arm, 1.3% in the dual therapy arm, and 0% in the control group. The majority of diarrhea events occurred in the early treatment phase and were manageable.

BeOne has secured key regulatory milestones for the novel combination regimen globally. The U.S. Food and Drug Administration (FDA) has accepted the supplemental Biologics License Application (sBLA) for tislelizumab and granted Priority Review status for the new indication in HER2-positive GEA.

In China, the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) has accepted dual sBLAs for both zanidatamab and tislelizumab for the frontline treatment of advanced or metastatic HER2-positive gastroesophageal adenocarcinoma.

BeOne holds exclusive commercial rights to zanidatamab across Asia excluding India and Japan, Australia and New Zealand. The company is advancing regulatory submissions in these regional markets to accelerate patient access to this groundbreaking therapy.