On Tuesday, the U.S. Food and Drug Administration (FDA) approved Jazz Pharmaceuticals plc’s (NASDAQ: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 (NASDAQ:ONC) under license agreements from Zymeworks Inc. (NASDAQ: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 Benzinga Pro data.
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