A multicenter retrospective study of PD-1 blockade plus chemotherapy as first-line therapy in advanced hepatoid adenocarcinoma of the stomach.

Purpose: This study aims to evaluate the efficacy and safety of PD-1 blockade in combination with chemotherapy for patients with advanced hepatoid adenocarcinoma of the stomach (HAS).

Materials and methods: This study retrospectively collected data from 25 patients with advanced HAS who received first-line PD-1 blockade combined with chemotherapy across 6 centers between January 2018 and January 2024. Progression-Free Survival (PFS) and Overall Survival (OS) were assessed using Kaplan-Meier (KM) curves.

Results: This study included 25 patients with HAS, all of whom received a first-line treatment regimen combining PD-1 blockade and chemotherapy. The Objective Response Rate (ORR) and Disease Control Rate (DCR) were 76.0% and 88.0%, respectively. The median follow-up time was 13.1 months, with a median Progression-Free Survival (mPFS) of 10.2 months (95% CI: 6.3-14.1) and a median Overall Survival (mOS) of 20.3 months (95% CI: 11.3-29.4). A total of 20 patients (80.0%) experienced adverse reactions of varying degrees, with white blood cell (WBC) count decreased (12, 48.0%) being the most common adverse event. Two patients experienced fatal adverse events (grade 5),both of which were unrelated to the PD-1 blockade.

Conclusion: Patients with HAS can derive survival benefits from first-line treatment with PD-1 blockade combined with chemotherapy, and the treatment is well tolerated. Furthermore, this pathological subtype may serve as a predictive indicator of favorable efficacy for PD-1 blockade, regardless of the patients' PD-L1 combined positive score (CPS).