Severe weight loss during PD-1 treatment is a risk sign of poor prognosis for advanced GC patients.

Objective: To verify whether severe weight loss is a reasonable risk sign for the effect of PD-1 treatment in advanced gastric cancer (GC) patients.

Methods: 127 metastatic or recurrent GC patients treated with PD-1 inhibitors in Xuzhou Central Hospital were involved in this study. Two cohorts with different variables were built; one was used to reveal the relationship between body weight loss and overall survival (OS), and the other was used to find which body composition contributed to the weight loss. Variables were collected at PD-1 inhibitor initiation (baseline) and week 6 of treatment. Patients were followed up from the end of therapy to November 2022. Overall survival (OS) and disease-free survival (DFS) were recorded.

Results: 127 patients with metastatic/recurrent gastric cancer received PD-1 treatment, among whom 117 had complete weight data. After screening, data from 69 patients were used for body composition assessment. The study found that 33 patients who lost more than 2% of their body weight within six weeks had poorer OS and DFS, with medians of 9.5 months and 6 months, respectively. Cox regression analysis showed that weight loss of more than 2% and treatment methods was an independent risk for poor OS and DFS. Further analysis revealed that weight loss was mainly caused by a reduction in adipose tissue, rather than muscle mass.

Conclusion: Severe weight loss is a potential monitor for the treatment effect of PD-1 inhibitor in advanced GC patients.