Jazz’s Ziihera and BeOne’s Tevimbra plus chemotherapy led to what Truist Securities dubbed one of the strongest overall survival signals ever reported in a type of gastroesophageal cancer.
After notching a high-profile cancer approval a few months ago, Jazz Pharmaceuticals is back with new data showing that its HER2 antibody Ziihera significantly improves survival when used as part of a first-line regimen in patients with locally advanced or metastatic gastroesophageal adenocarcinoma.
These findings come from the Phase III HERIZON-GEA-01 study, which tested two Ziihera combinations: one with chemotherapy, the other with both chemotherapy and BeOne’s Tevimbra. As an active control, the trial used a regimen of Herceptin with chemotherapy. More than 900 patients were enrolled.
Results, presented in a Tuesday news release, showed a 35% drop in the risk of disease progression or death in patients treated with Ziihera and chemotherapy. Add-on Tevimbra slightly improved this progression-free survival (PFS) benefit, raising it to 37%. Median PFS for both combinations was more than four months longer than in the Herceptin-based control group.
Writing to investors on Tuesday, analysts at Truist Securities called the Ziihera readout “practice-changing,” pointing specifically to “the strongest OS signals ever reported” across randomized studies of first-line HER2-positive gastroesophageal adenocarcinoma. “The triplet’s >7-mo [median OS] improvement is practice-changing in any GI setting,” the analysts added.
Truist also pointed to Ziihera’s median duration of response, which reached 14.3 months and 20.7 months for its doublet and triplet regimens, respectively. As for safety, Jazz reported adverse events that were largely consistent with Ziihera’s known profile, with no new signals of concern. Grade 3 or higher treatment-related adverse events hit 59.6% for the doublet regimen and 71.8% for the triplet.
“Beating a high-performing trastuzumab [Herceptin] control,” the analysts said, “strongly supports HER2 backbone replacement, not niche use.”
With these data, Jazz plans to “move rapidly toward FDA submission,” Chief Medical Officer Rob Iannone said in the company’s statement on Tuesday. The biotech is also set to present these findings at the upcoming 2026 ASCO Gastrointestinal Cancers Symposium.
Given intravenously, Ziihera is a bispecific antibody that binds to two sites on the HER2 protein, in turn disrupting the receptor’s downstream signaling. Through this mechanism, Ziihera triggers the destruction of cancer cells and prevents the growth of the tumor. The FDA granted Ziihera accelerated approval in November 2024 for unresectable or metastatic HER2-positive biliary tract cancer. Jazz is also developing Ziihera for other solid tumors, including breast cancer and colorectal carcinoma.
Jazz had a positive run of data in 2025 coming off its purchase of Chimerix in March. The company picked up the glioma drug dordaviprone, presented new findings for it in May, and won FDA approval for it— to be marketed as Modeyso—in August.
