Amgen's Bemarituzumab Improves Survival in Gastric Cancer Trial, Notes Ocular Side Effects

Amgen's gastric cancer drug, bemarituzumab, has shown improved survival rates in a Phase 3 trial, meeting its primary endpoint. However, the drug also caused ocular side effects, such as reduced visual acuity and punctate keratitis. Amgen is navigating challenges with its established product portfolio and biosimilar franchises, but upcoming clinical milestones are expected to generate investor enthusiasm. The company's stock is up 0.40% at $278.23.

Zai Lab Limited (NASDAQ: ZLAB; HKEX: 9688) has announced positive topline Phase 3 results for bemarituzumab in the treatment of FGFR2b-positive first-line gastric cancer. The Phase 3 FORTITUDE-101 clinical trial, evaluating bemarituzumab plus chemotherapy (mFOLFOX6) versus chemotherapy alone, met its primary endpoint of overall survival (OS) at a pre-specified interim analysis.

The trial demonstrated a statistically significant and clinically meaningful improvement in OS for patients with FGFR2b overexpression compared to chemotherapy alone. The drug showed a significant reduction in mortality rates, offering a potential breakthrough in the treatment of gastric cancer, particularly in advanced stages where the five-year survival rate is less than 10% [1].

Gastric cancer is a significant global health issue, with approximately 358,700 new cases and 260,400 deaths annually in China alone [2]. The disease is associated with a poor prognosis, particularly in advanced stages. Currently, there are no approved therapies specifically targeting FGFR2b overexpression in gastric cancer in China. Bemarituzumab's success in the Phase 3 trial highlights its potential to redefine the standard of care for this patient population.

Dr. Rafael Amado, M.D., President, Head of Global Research and Development at Zai Lab, commented, "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. The success of the global Phase 3 FORTITUDE-101 study underscores the potential of bemarituzumab to significantly improve patient outcomes."

The most common treatment-emergent adverse events (25%) in patients treated with bemarituzumab plus chemotherapy were reduced visual acuity, punctate keratitis, anemia, 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 [3].

Detailed results from the trial will be shared at a future medical meeting. Zai Lab holds the development and commercialization rights for bemarituzumab in mainland China, Hong Kong, Macau, and Taiwan. Bemarituzumab has been granted Breakthrough Therapy designation by the China Center for Drug Evaluation for the treatment of FGFR2b-positive gastric and gastroesophageal junction adenocarcinoma [4].

Zai Lab's stock price is up 0.40% at $278.23, reflecting investor enthusiasm for the positive trial results and the potential market opportunity for bemarituzumab. The company is navigating challenges with its established product portfolio and biosimilar franchises but is expected to generate investor interest with upcoming clinical milestones.

References:
[1] https://www.morningstar.com/news/business-wire/20250630980449/zai-lab-announces-positive-topline-phase-3-results-for-bemarituzumab-in-fibroblast-growth-factor-receptor-2b-fgfr2b-positive-first-line-gastric-cancer
[2] Bray F, et al. CA Cancer J Clin. 2024;74(3);229-263
[3] Health Commission of The People’s Republic Of China N. National guidelines for diagnosis and treatment of gastric cancer 2022 in China (English version). Chin J Cancer Res. 2022;34(3):207-237.
[4] Li HQ, Zhang H, Zhang HJ, Wang YX, Wang XB, Hou HF. Survival of gastric cancer in China from 2000 to 2022: A nationwide systematic review of hospital-based studies. J Glob Health 2022;12:11014.