Jazz Pharmaceuticals (NASDAQ:JAZZ) saw its stock soar 25% after unveiling encouraging Phase 3 results for its investigational cancer treatment Ziihera, which is being studied for gastroesophageal cancer.
The Ireland-based biotech said the late-stage HERIZON-GEA-01 study showed that Ziihera combined with chemotherapy—and a second regimen pairing Ziihera with Tevimbra plus chemotherapy—both delivered statistically significant gains in progression-free survival versus the current benchmark regimen of trastuzumab and chemotherapy.
The trial assessed Ziihera (zanidatamab-hrii) as a frontline option for patients with HER2-positive locally advanced or metastatic gastroesophageal adenocarcinoma. The group receiving Ziihera, Tevimbra, and chemotherapy also achieved a statistically significant overall survival benefit, while Ziihera paired solely with chemotherapy produced “a clinically meaningful effect with a strong trend toward statistical significance” for overall survival.
Dr. Kohei Shitara, the study’s lead investigator from Japan’s National Cancer Center Hospital East, said the findings indicate Ziihera-based regimens could have “the potential to become the new standard of care” for first-line HER2-positive gastroesophageal cancer.
The global study enrolled 914 participants across roughly 300 clinical sites in more than 30 countries. Jazz plans to file a supplemental Biologics License Application with the FDA in the first half of 2026 seeking approval for Ziihera in this setting.
Jazz will share full results at a medical congress in the first quarter of 2026 and submit the data to a peer-reviewed journal. Safety outcomes aligned with the known profiles of the individual agents, and no new safety concerns emerged.
This marks the first Phase 3 readout for Ziihera, which is also under evaluation for several additional tumor types, including biliary tract and breast cancers.