[Clinical characteristics and microbiome analysis in patients with anti-programmed cell death protein 1 related...

Objective: To analyze clinical characteristics and monitor microbiome changes in patients with anti-PD-1 associated colitis. Methods: Two patients with non-small cell lung cancer who developed colitis after treated with anti-PD-1 antibodies were retrospectively analyzed in Peking Union Medical College Hospital from January 2019 to January 2020. The clinical symptoms, endoscopic and pathological manifestations, as well microbiome changes were analyzed and compared during pre-treatment, post-treatment and relapse. Results: The main clinical manifestations included diarrhea, elevated inflammatory indicators, colonic mucosal diffuse hyperemic edema with erosion by endoscopy. Changes in the structure of crypts were common pathological characteristics. Glucocorticoids were effective agents, which achieved clinical remission and mucosal healing. The microbiome composition of OTUs was different. After glucocorticoid treatment, the alpha diversity Observed species, Shannon, Simpson, Chao1, ACE indexes all decreased. The Firmicutes decreased with Bacteroidetes increasing in phylum level; while the Bacteroides increased with Ruminococcaceae decreasing in genus level. Lactobacillus was the potentially beneficial genus. Conclusion: Patients developing anti-PD-1 associated colitis have characteristic clinical and pathological manifestations. Glucocorticoids are effective treatment. The fecal microbiome diversity, relative abundance of major phylum and genus have changed after treatment.