Amgen Reports Reduced OS Benefit for FGFR2b Antibody Bemarituzumab in Phase 3 FORTITUDE-101 Trial

▎Armstrong

On September 3, 2025, Amgen announced at the Wells Fargo Healthcare conference that the final analysis of the Phase III clinical trial FORTITUDE-101 for FGFR2b antibody Bemarituzumab in combination with chemotherapy as a first-line treatment for gastric cancer was completed. In the earlier interim analysis, OS showed a statistically significant and clinically meaningful improvement, but the magnitude of OS benefit diminished in the final analysis.

In June this year, Amgen announcedFORTITUDE-101 Phase III Clinical Trial Interim Analysis Meets Primary OS Endpoint, Demonstrating Statistically Significant and Clinically Meaningful Improvement.

Yesterday, Amgen's stock price fell by 1%, and Zai Lab's stock price fell by 6%.

Bemarituzumab is currently undergoing multiple clinical trials, and topline data from another Phase III trial of the triplet therapy, FORTITUDE-102, is expected to be released in the second half of 2025 or the first half of 2026.

Summary

In China, Zai Lab has acquired the rights to Bemarituzumab in the Greater China region. Several other domestic pharmaceutical companies are also developing FGFR2b ADC drugs, including BeiGene, Anlicure, Simcere Pharmaceutical, Huadong Medicine, and Transcenta Holding. Among them, BeiGeneBG-C137 is an FGFR2b ADC with a TOPOI inhibitor as the payload, a DAR value of 8, and utilizes a stable linker to avoid corneal toxicity.