A Major Setback for Amgen: Bemarituzumab's Gastric Cancer Ambitions Dim as Final Data Fails to Impress

Amgen, a biotechnology giant, is facing a significant challenge to one of its key pipeline assets, bemarituzumab, an investigational drug aimed at treating frontline gastric and gastroesophageal junction (GEJ) cancer. The final analysis from its pivotal Phase 2 FIGHT study has revealed a critical shortfall, casting a shadow over the drug’s future and the company’s strategic acquisition.

Bemarituzumab targets the Fibroblast Growth Factor Receptor 2b (FGF2b), a protein overexpressed in a subset of gastric cancers. Back in 2021, the initial data from the Phase 2 FIGHT study generated considerable excitement, demonstrating promising efficacy in tumors with high FGF2b expression. This early success was so compelling that it prompted Amgen to acquire Five Prime Therapeutics, the original developer of the drug, for a hefty $1.9 billion, largely based on the potential of bemarituzumab to transform gastric cancer treatment.

The initial analysis had indicated improvements in both progression-free survival (PFS) and overall survival (OS) for patients treated with bemarituzumab in combination with mFOLFOX6 chemotherapy. However, the recently unveiled final data tells a different story. While the progression-free survival benefit remains intact, the all-important overall survival benefit, which was previously trending positively, did not achieve statistical significance. This miss is a considerable blow, as overall survival is often considered the gold standard endpoint for oncology drug approvals, particularly for a potential accelerated approval pathway.

Industry analysts have quickly weighed in on the implications. Matt Phipps from William Blair, for instance, noted the lack of statistically significant OS benefit and expressed skepticism regarding the feasibility of a Phase 3 trial. Given the substantial cost associated with such a trial, the current data makes a compelling case for further investment much harder to justify. The original $1.9 billion acquisition was predicated on stronger evidence of a survival advantage, which now appears less robust.

In response, Amgen acknowledged that the overall survival benefit did not meet statistical significance. However, the company reiterated that the drug was well-tolerated and confirmed the previously observed progression-free survival benefit. Amgen stated that it is currently reviewing the complete dataset to determine the appropriate next steps for the bemarituzumab program, leaving open the possibility, albeit a more challenging one, for a Phase 3 study.

This development undoubtedly weakens the investment case for bemarituzumab and poses a significant hurdle for Amgen’s oncology pipeline. While the drug’s journey isn’t definitively over, the path forward for this once-promising gastric cancer therapy now appears considerably more arduous, reflecting the inherent risks and complexities of drug development in severe diseases.