Efficacy and safety of S-1 plus oxaliplatin combined with apatinib and camrelizumab as neoadjuvant therapy for patients with locally advanced gastric or gastroesophageal junction adenocarcinoma: a protocol for a single-arm phase II trial

Gastric cancer, as the fifth most diagnosed malignancy and the fourth leading cause of cancer-related death globally, remains a significant health concern. The potential effect of the programmed death-1 (PD-1) inhibitor, when used alongside chemotherapy and antiangiogenic agents in neoadjuvant therapy for gastric cancer, has yet to be explored in the published literature. This study aims to evaluate the efficacy and safety of the S-1 plus oxaliplatin (SOX) regimen when combined with apatinib and camrelizumab (SOXAC) as neoadjuvant therapy for patients with locally advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma. A single-arm, open-label, single-center phase II clinical trial has been designed to evaluate the safety and efficacy of the SOXAC regimen as neoadjuvant therapy for patients diagnosed with locally advanced gastric or GEJ adenocarcinoma (cT2-3N + M0 or T4NxM0). Eligible patients are to receive 2 cycles of SOXAC and 1 cycle of SOX regimen with camrelizumab (SOXC) as neoadjuvant therapy prior to radical surgery, and 3 cycles of SOXC as postoperative adjuvant therapy. The primary endpoint is major pathological remission (MPR), while secondary endpoints include pathological complete response (pCR) rate, R0 resection rate, objective response rate (ORR), operation-related outcomes, and safety. The SOX regimen remains a leading choice for neoadjuvant chemotherapy in Eastern countries. Recent studies suggest that combining chemotherapy, targeted agents, and immune checkpoint inhibitors can enhance the antitumor immune response. This phase II clinical trial seeks to assess the safety and efficacy of the SOXAC regimen as neoadjuvant therapy for patients with locally advanced resectable gastric or GEJ adenocarcinoma, while also exploring the correlation between biomarkers and efficacy.Trial Registration Chinese Clinical Trial Registry (ChiCTR): ChiCTR2200062285 ( https://www.chictr.org.cn/ ).