Abstract
BACKGROUND: Alpha-fetoprotein elevated gastric cancer (AFPGC) got growing interests for its aggressive nature and unfavorable prognosis. Here, a phase 1 dose escalation study was conducted to evaluate safety and efficacy of zimberelimab (GLS-010, anti-PD-1) plus lenvatinib and chemotherapy (XELOX) as the first-line treatment for AFPGC. METHODS: Histologically confirmed HER2-negative, advanced GC patients with elevated serum AFP level (≥ 20 ng/ml) were screened. Using a 3 + 3 dose escalation design, patients were administered varying doses of lenvatinib (12, 16, 20 mg) with GLS-010 and XELOX. The primary endpoints were safety and determination of recommended phase II dose (RP2D). Secondary endpoints included overall response rate (ORR), progression-free survival (PFS) and disease control rate. RESULTS: Nine patients were enrolled with no dose-limiting toxicities observed. Most frequent treatment-related AEs were fatigue (55.6%), hand-foot syndrome (55.6%) and rash (55.6%), and no grade ≥ 4 AEs were reported. All patients exhibited disease control with ORR reaching 33.3%. The median PFS and OS reached 7.67 months (95% CI 4.07-11.27) and 13.17 months (95% CI 2.78-23.56), respectively. Serum AFP level was found correlated with therapeutic responses. Further 16s rRNA sequencing analysis demonstrated altered gut microbiota with elevated abundance of Lachnospiraceae bacterium-GAM79 and Roseburia hominis A2-183. CONCLUSIONS: GLS-010 plus lenvatinib and XELOX demonstrated a manageable safety profile with promising efficacy for AFPGC. With RP2D of lenvatinib determined as 16 mg, further expansion cohort is now ongoing. Translational investigation suggested that serum AFP can be indictive for therapeutic responses and certain microbiota species indicating favorable responses to immunotherapy was elevated after the combinational treatment.