Low-dose apatinib combined with camrelizumab and the SOX regimen in the neoadjuvant treatment of locally advanced gastric/gastroesophageal junction adenocarcinoma (SPACE-neo): a protocol for an open-label, single-arm, clinical trial.

Background: Neoadjuvant chemotherapy with S-1 plus oxaliplatin (SOX regimen) has shown promising results in pathological response rate and survival rate in patients with locally advanced resectable gastric cancer (LAGC). We previously carried out the SPACE study to assess efficacy and safety of low-dose apatinib combined with camrelizumab and the SOX regimen as a first-line treatment of advanced gastric/gastroesophageal junction adenocarcinoma (AGC/GEJC). The preliminary results demonstrated a high objective response rate. However, the SPACE study was conducted in patients with AGC, but the efficacy of LAGC patients is not yet known. The SPACE-neo study is designed to investigate whether this combination could improve outcomes in patients with locally advanced gastric/gastroesophageal junction cancer (LAGC/GEJC) as neoadjuvant therapy. Methods: SPACE-neo is a prospective, open-label, single-arm study conducted in China at the First Affiliated Hospital of Nanjing Medical University (Jiangsu Province Hospital). Thirty-two patients with human epidermal growth factor receptor 2 (HER2)-negative or HER2-unknown LAGC/GEJC confirmed by histopathology or cytology will be recruited. Included patients shall be clinically staged as M0 and either T3 to T4 or N+ assessed by ultrasound endoscopy and thoracoabdominal-enhanced computed tomography or magnetic resonance imaging. The patients will receive three cycles of this combined regimen as a neoadjuvant treatment. Each patient will receive screening visits within 2 weeks before the first cycle and planned visits before every cycle of treatment. Key monitoring data include imaging data, pathological findings, and adverse events associated with neoadjuvant and surgical treatment. The primary endpoints are major pathological response (MPR) and safety. MPR is the proportion of patients whose residual tumor cells make up less than 10% of the primary tumor from among the total cohort. Clopper-Pearson method will be used to estimate the 95% confidence interval of MPR and safety data will be reported as descriptive statistical analysis. Discussion: The SPACE-neo trial aims to evaluate the safety and preliminary efficacy of this regimen in the neoadjuvant treatment of LAGC/GEJC. It is hoped that the study can achieve a higher pathological response rate and longer survival rate. Trial Registration: ChiCTR.gov.cn: ChiCTR2100049305.