On June 30, 2025 Zai Lab Limited (NASDAQ: ZLAB; HKEX: 9688) reported the Phase 3 FORTITUDE-101 clinical trial evaluating first-line bemarituzumab plus chemotherapy (mFOLFOX6) met its primary endpoint of overall survival (OS) at a pre-specified interim analysis (Press release, Zai Laboratory, JUN 30, 2025, View Source [SID1234654181]).
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Bemarituzumab plus chemotherapy demonstrated a statistically significant and clinically meaningful improvement in OS as compared to placebo plus chemotherapy in people living with unresectable locally advanced or metastatic gastric or gastroesophageal junction (G/GEJ) cancer with FGFR2b overexpression and who are non-HER2 positive. FGFR2b overexpression was defined as 2+/3+ staining in ≥10% of tumor cells by centrally performed immunohistochemistry (IHC) testing.
Gastric cancer is the fifth leading cause of cancer-related death worldwide, with nearly one million new cases and over 650,000 deaths globally each year 1, highlighting a critical unmet medical need. In China, there are over 350,000 new cases each year. The disease is associated with a poor prognosis, particularly in advanced stages where the five-year survival rate is less than 10%. There are currently no approved therapies specifically targeting FGFR2b overexpression in gastric cancer in China.
"Bemarituzumab is the first FGFR2b inhibitor to demonstrate a statistically and clinically significant overall survival benefit in a randomized Phase 3 trial for the first-line treatment of FGFR2b-positive gastric cancer," said Dr. Rafael Amado, M.D., President, Head of Global Research and Development at Zai Lab. "The success of the global Phase 3 FORTITUDE-101 study highlights the potential of bemarituzumab to redefine the standard of care for a patient population that has faced poor outcomes with existing therapies. We are proud to have contributed meaningfully to this pivotal trial, including a substantial number of patients enrolled in China. Based on these results, and the regulatory Breakthrough Designation, we plan to move rapidly toward regulatory submission in China to bring this transformative therapy to patients as quickly as possible."
The most common treatment-emergent adverse events (>25%) in patients treated with bemarituzumab plus chemotherapy were reduced visual acuity, punctate keratitis, anaemia, neutropenia, nausea, corneal epithelium defect and dry eye. While ocular events were consistent with the Phase 2 experience and observed in both arms, they occurred with greater frequency and severity in the Phase 3 bemarituzumab arm.
Detailed results from the trial will be shared at a future medical meeting.
Zai Lab holds the development and commercialization rights for bemarituzumab for mainland China, Hong Kong, Macau, and Taiwan. Bemarituzumab has been granted Breakthrough Therapy designation by the China Center for Drug Evaluation of the National Medical Products Administration for the treatment of FGFR2b-positive gastric and gastroesophageal junction adenocarcinoma.
A Phase 3 study of bemarituzumab plus chemotherapy and nivolumab is also ongoing in patients with first-line gastric cancer, with data readout anticipated in H2 2025.
About FGFR2b
The FGFR2b protein (also known as fibroblast growth factor receptor 2b) is an emerging biomarker which, when overexpressed, promotes aberrant signaling leading to tumor cell proliferation.2
The FGFR2b protein is overexpressed by G/GEJ tumor cells in approximately 38% of patients with advanced G/GEJ cancer. FGFR2b protein overexpression is defined as 2+/3+ staining intensity on tumor cell membrane, as detected by immunohistochemistry (IHC) testing. In approximately 16% of patients with advanced G/GEJ cancer, FGFR2b protein overexpression is observed on ≥10% of tumor cells by IHC.3
About FORTITUDE-101
FORTITUDE-101 is a randomized, multi-center, double-blind, placebo-controlled Phase 3 study of bemarituzumab plus mFOLFOX6 versus placebo plus mFOLFOX6 as first-line therapy in advanced G/GEJ cancer with FGFR2b overexpression. The FORTITUDE-101 trial spanned 300 sites across 37 countries, with 547 patients enrolled.
The primary outcome measure of the trial is overall survival in patients with FGFR2b ≥10% 2+/3+ tumor cell staining. Key secondary outcome measures include progression-free survival and overall response rate. Candidates were excluded from the trial if they were known to be human epidermal growth factor receptor 2 (HER2) positive. FORTITUDE-101 included more comprehensive ocular-related monitoring than previous studies of bemarituzumab.
About Gastric Cancer in China
Gastric cancer is the fifth most common cancer worldwide, while China bears one of the highest gastric cancer burdens in the world with an estimated 358,700 new cases and 260,400 deaths annually.4 In China, approximately 80% of gastric cancer patients are diagnosed at an advanced or metastatic stage5. For those diagnosed with Stage IV gastric cancer, the overall 5-year survival rate is less than 10%6. Patients with advanced gastric and GEJ cancer that overexpress the FGFR2b protein may be associated with poor prognosis.