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Ziihera® Combinations Show Promise for HER2+ Advanced Gastroesophageal Adenocarcinoma at ESMO 2026

In an exciting update from the ESMO Congress 2026 held in Madrid, Spain, Jazz Pharmaceuticals reported groundbreaking findings regarding Ziihera® (zanidatamab-hrii) in treating HER2-positive (HER2+) advanced gastroesophageal adenocarcinoma (GEA). The Phase 3 HERIZON-GEA-01 trial revealed compelling results regarding overall survival (OS) for patients receiving Ziihera in combination with chemotherapy, with or without Tevimbra® (tislelizumab-jsgr).

Key Results of the HERIZON-GEA-01 Trial

The trial's results were presented as a late-breaking rapid oral presentation during the congress, showcasing that nearly 40% of participants who received Ziihera, in conjunction with tislelizumab and chemotherapy, were alive after three years. This was particularly significant given the difficulty many patients have achieving long-term survival in advanced GEA. Dr. Kohei Shitara, the principal trial investigator, noted that these findings strongly endorse Ziihera-containing regimens as a potential new standard of care for patients with HER2+ advanced GEA.

The median OS for those treated with the Ziihera combination reached an impressive 27 months, surpassing the 19.6 months seen with trastuzumab plus chemotherapy. This represents a substantial reduction in the risk of death, affirming the efficacy of the Ziihera regimen.

Detailed Findings

A deeper dive into the data shows that the Ziihera plus tislelizumab and chemotherapy combination maintained a significant survival advantage over trastuzumab with chemotherapy. The trial's established metrics show:

• - Median OS: 27.0 months (95% CI 23.7-32.2) for Ziihera plus tislelizumab and chemotherapy, compared to 19.6 months for trastuzumab plus chemotherapy.
• - Risk Reduction: Ziihera plus tislelizumab reduced the risk of death by a remarkable 35% compared to trastuzumab alternatives.
• - Long-Term Survival: The estimates reveal that approximately 39.8% of patients treated with the combination were still alive at three years, indicating substantial advancements in managing this challenging cancer.

Significance of the Results

These findings are pivotal as GEA is known for its poor prognosis. The overall five-year survival rate for metastatic GEA is less than 10%, emphasizing the desperate need for effective treatment options. The efficacy of Ziihera, a bispecific HER2-directed antibody, signals a hopeful turn in patient care for those afflicted with HER2+ cancers.

Furthermore, the favorable safety profiles of Ziihera's combinations, consistent with prior trials, suggest that patients may tolerate extended treatment periods. This durability of effect underpins the potential role of Ziihera as a front-line therapeutic option.

Recent Regulatory Recognition

Following these promising trial outcomes, Ziihera-containing combinations have recently been designated as preferred therapies in the NCCN Clinical Practice Guidelines for Gastric Cancer. Notably, Ziihera plus tislelizumab and chemotherapy has been recognized as the only preferred regimen for HER2+ patients, irrespective of PD-L1 status, showing a shift in clinical practice standards based on updated evidence.

Forward-Looking Statements

The breakthrough findings underscore a robust commitment to improving patient outcomes in GEA. Jazz Pharmaceuticals, together with BeOne Medicines, is continuing to research and develop Ziihera for broader therapeutic uses, aspiring to change the landscape for solid tumors expressing HER2. Regulatory approvals and ongoing studies will further shape the clinical pipeline as these therapies become integral to oncology practices worldwide.

As the study progresses, it is crucial for stakeholders to keep abreast of emerging evidence and advancements in HER2-targeted therapies like Ziihera, which could significantly benefit patients grappling with the severe implications of advanced gastroesophageal malignancies.