Eligible patients were randomized into two groups: the sodium propionate group and the control group. In the control group, patients received placebo combined with anti-PD-1 therapy plus chemotherapy without additional sodium propionate intervention. In the sodium propionate group, on the basis of anti-PD-1 therapy combined with chemotherapy, patients were additionally administered oral sodium propionate capsules at a dose of 500 mg (1 capsule) twice weekly, with a total intervention duration of 12 weeks. The primary and secondary outcome indicators will be collected for subsequent analysis.