A new case series reports the successful treatment of immune checkpoint inhibitor (ICI)-associated colitis with faecal microbiota transplantation (FMT).

ICIs have emerged as effective agents to treat a number of cancer types. However, these drugs can cause immune-related adverse effects, including ICI-associated colitis. Immunosuppressive therapies, such as corticosteroids or anti-TNF agents, are used to manage ICI toxicity, yet these drugs also carry risks of adverse effects and many patients receive no benefit.

On the basis that other forms of colitis, including IBD, might be improved by FMT, Wang and colleagues investigated the potential of this microbial therapy to treat ICI-associated colitis. Two patients treated with ICIs who were experiencing severe colitis refractory to immunosuppressive agents were recruited and received FMT via colonoscopy from one healthy donor.

FMT completely resolved clinical symptoms of colitis in both patients, although one individual required a second FMT treatment. This resolution was accompanied by marked endoscopic symptom improvement and reduced inflammatory infiltrate.

Analysis of the gut microbial taxa before and after FMT revealed that recipient microbiota became similar to the donor microbiota, yet this change was not maintained. Notably, the gut microbiota of the two patients had different long-term responses to FMT: one patient showed expansion of Clostridia and Bifidobacterium taxa, whereas the other patient experienced increased abundance of Escherichia and decreased abundance of Bacteroides.

Although small, this study indicates that FMT might be a promising approach to mitigate ICI-associated colitis. Larger-scale trials are anticipated.