Clinical study of adebrelimab in combination with apatinib and irinotecan for PD-1 inhibitor-ineffective advanced-stage gastric cancer: study protocol for a single-arm, single-centre, exploratory trial.

INTRODUCTION

Immunotherapy has revolutionised cancer treatment. Immune checkpoint inhibitors have demonstrated significant efficacy across multiple tumour types, including gastric cancer, where several approved programmed cell death 1/programmed cell death-ligand 1 (PD-1/PD-L1) inhibitors show promising antitumour activity. While PD-L1 expression serves as a predictive biomarker for PD-1 inhibitor response, and PD-L1-positive patients generally show better outcomes, therapeutic resistance remains a challenge. Many initial responders eventually develop resistance, and surprisingly, some PD-L1-positive patients fail to achieve expected response rates, indicating emerging resistance mechanisms in potentially responsive populations. Adebrelimab, a PD-L1 inhibitor, demonstrates mechanistic advantages over PD-1 inhibitors, with clinical studies suggesting promising therapeutic potential. When combined with irinotecan, apatinib has shown efficacy in second-line gastric cancer treatment. This study aims to evaluate the efficacy and safety of combining adebrelimab with apatinib and irinotecan for advanced gastric cancer refractory to PD-1 inhibitors.

METHOD AND ANALYSIS

This single-arm, single-centre exploratory trial will be conducted at Renji Hospital, enrolling 32 patients aged 18-75 years. Eligible patients must have initially achieved partial response, complete response or stable disease with progression-free survival (PFS)≥3 months during prior immunotherapy but subsequently progressive disease on imaging. Treatment will continue until meeting discontinuation criteria. The primary endpoint is objective response rate with Clopper-Pearson 95% CI. Secondary endpoints include disease control rate (95% CI), PFS and overall survival (estimated by Kaplan-Meier method), along with safety assessments.

ETHICS AND DISSEMINATION

All participants will provide informed consent. The protocol has been approved by the Shanghai Jiaotong University School of Medicine, Renji Hospital Ethics Committee (LY2023-201-C). The results will be disseminated through peer-reviewed manuscripts, reports and presentations.

TRIAL REGISTRATION NUMBER

ChiCTR2300077329.