On Tuesday, the U.S. Food and Drug Administration (FDA) approved Jazz Pharmaceuticals plc's Jazz Pharmaceuticals (JAZZ) two Ziihera-containing combination regimens as first-line treatments for adults with unresectable locally advanced or metastatic HER2-positive gastroesophageal adenocarcinoma.
Zanidatamab is being developed in multiple clinical trials as a targeted treatment option for patients with solid tumors that express HER2. Zanidatamab is being developed by Jazz and BeOne Medicines Ltd BeOne Medicines (ONC) under license agreements from Zymeworks Inc. Zymeworks (ZYME), which first developed the molecule.
FDA Approval Details and Trial Results
The regulatory decision covers Ziihera (zanidatamab-hrii) paired with fluoropyrimidine- and platinum-containing chemotherapy, both with and without BeOne Medicines' Tevimbra (tislelizumab-jsgr).
Gastroesophageal adenocarcinoma comprises gastric, gastroesophageal junction, and esophageal cancers, ranking as the fifth most common cancer globally. Approximately 20% of patients test positive for HER2, and the United States sees over 31,000 new stomach cancer diagnoses annually.
Improved Survival Outcomes
In clinical evaluations, both Ziihera combinations significantly improved progression-free survival across the overall HER2-positive population.
The regimens reduced the risk of disease progression or death by 35%, extending median progression-free survival to 12.4 months compared to 8.1 months for patients receiving trastuzumab plus chemotherapy.
Furthermore, the triplet combination of Ziihera, tislelizumab-jsgr, and chemotherapy delivered a statistically significant overall survival benefit. It reduced the risk of death by 28% compared to the trastuzumab control group.
Patients achieved a median overall survival of 26.4 months versus 19.2 months. This greater than seven-month extension represents the longest median overall survival recorded in a Phase 3 trial for advanced HER2-positive GEA.
These survival enhancements remained consistent across key prespecified patient subgroups, including geographic regions and PD-L1 statuses.
JAZZ/ZYME Stock Price Activity: Jazz Pharmaceuticals shares were up 3.82% at $264.19, and Zymeworks shares were down 8.98% at $26.18 at the time of publication on Tuesday, according to market data.
