Jazz Pharmaceuticals Plc ( JAZZ ) shares are popping on Monday following the company’s positive results of its Phase 3 HERIZON-GEA-01 trial, which assessed Ziihera in combination with chemotherapy, with or without the PD-1 inhibitor Tevimbra, as a first-line treatment for HER2-positive locally advanced or metastatic gastroesophageal adenocarcinoma (GEA).

What Happened: When compared to the control group that received trastuzumab and chemotherapy, Jazz Pharmaceuticals ( JAZZ ) found that both treatment combinations, Ziihera with chemotherapy alone and Ziihera with tislelizumab and chemotherapy, exhibited statistically and clinically significant improvements in progression-free survival. The trial focuses on esophageal, stomach and gastroesophageal junction cancers.

Furthermore, overall survival increased in a statistically significant and clinically meaningful way when Ziihera, tislelizumab, and chemotherapy were combined. At this initial analysis, the Ziihera plus chemotherapy arm showed a clinically significant effect with a strong trend toward statistical significance for overall survival. A follow-up interim analysis is planned for mid-2026.

According to Dr. Kohei Shitara, director of the Department of Gastrointestinal Oncology at the National Cancer Center Hospital East in Kashiwa, Japan, "zanidatamab plus chemotherapy combination, with and without tislelizumab, has the potential to become the new standard of care for patients in HER2+ first-line locally advanced unresectable or metastatic GEA.”

“We believe these results will be practice changing, and highlight the potential impact of Ziihera for patients who are facing a devastating diagnosis and limited options in locally advanced or metastatic GEA,” said Rob Iannone, executive vice president and chief medical officer of Jazz Pharmaceuticals ( JAZZ ). “We expect Ziihera to become the new standard of care anti-HER2 therapy for patients with HER2+ first-line metastatic GEA regardless of PD-L1 status.”

JAZZ Price Action: Jazz Pharmaceuticals ( JAZZ ) shares were up 20.49% at $170.11 at the time of publication on Monday. The stock is trading at a new 52-week high, according to Benzinga Pro.

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