PDCD1 and colitis: Patient specimens:A comparative analysis of fecal samples from patients receiving ICI treatment, with and without concomitant gastrointestinal toxicity, is to be performed using omics.Mice: Mice were administered 3% DSS and subsequently induced to form an immune checkpoint inhibitor-associated colitis model using dual anti-PD-1 and anti-CTLA-4 antibodies. Then, a quantity of mice is injected with Faecalibacterium prausnitzii.