Predictive value of body mass index on the efficacy of Sintilimab combined with SOX regimen for the first-line treatment of advanced inoperable gastric cancer

Abstract

Purpose: This study aims to investigate the predictive role of body mass index (BMI) on the efficacy of sintilimab combined with oxaliplatin + tiglio (SOX) in the first-line treatment for patients with advanced inoperable gastric cancer. Materials and methods: A retrospective analysis was conducted on 137 patients with advanced inoperable gastric cancer treated with sintilimab in conjunction with the SOX regimen at the Affiliated Hospital of Xuzhou Medical University from September 2020 to December 2023. Patients were categorized into the wasting group (BMI <18.5 kg/m²) and the non-wasting group (BMI ≥18.5 kg/m²) according to their BMI. There were 68 cases in the wasting group and 69 cases in the non-wasting group. Parameters including progression-free survival time (PFS), overall survival time (OS), objective remission rate (ORR), disease control rate (DCR), and adverse reactions were analyzed and compared between the two groups. Survival curves were plotted using the Kaplan–Meier method, and differences between the groups were assessed using the Log-rank test. Univariate and multivariate Cox regression analyses were performed to identify independent risk factors affecting OS. A column-line diagram model was constructed based on the independent factors affecting patients' OS, and the model’s discriminative ability was evaluated using the C-index, ROC curve, and calibration curve. The clinical benefit of the column-line diagram was assessed using DCA curves. Results: Patients in the non-wasting group exhibited significantly longer median PFS compared to those in the wasting group (10.3 months vs 7.85 months, P=0.012) and significantly longer median OS(19.8 months vs 17.4 months, P<0.01). The ORR (29.0% vs 14.7%, P=0.043) and DCR (62.3% vs 44.9%, P=0.049) were significantly better in the non-wasting group compared to the wasting group. There was no significant difference in the overall incidence of adverse events between the two groups (73.5% vs 66.7%, P=0.381), and no grade >3 adverse reactions or adverse reaction-related deaths occurred in either group. Multifactorial analysis revealed distant metastasis (HR=0.24, 95% CI=0.11-0.52), tumor size (HR=2.17, 95% CI=1.04-4.53), and BMI (HR=0.39, 95% CI=0.17-0.87) as independent prognostic factors affecting OS (all P-values <0.05). Furthermore, the constructed column-line graphical model demonstrated good accuracy and discrimination (C-index for the training set: 0.790 (0.724–0.857), C-index for the validation set: 0.690 (0.579–0.801). Conclusion: BMI serves as a convenient, efficient, and clinically valuable predictor of the efficacy of sintilimab in combination with the SOX regimen for the first-line treatment of patients with advanced inoperable gastric cancer.