Two cancer patients who experienced severe colitis as a result of immunotherapy have been successfully treated with faecal transplants.

Reporting in Nature Medicine Yinghong Wang from The University of Texas MD Anderson Cancer Center in Houston said colitis was one of the most common toxicities experienced by patients taking immune checkpoint inhibitors (ICI). Disease was often severe, closely resembling colitis associated with autoimmune pathophysiology.

“Recommendations regarding optimal management of ICI-induced colitis continue to evolve… Interestingly, recent randomized clinical studies suggest that other types of colitis, including Clostridium difficile-associated colitis and IBD, can be successfully treated by modulation of the gut microbiome with fecal microbiota transplantation (FMT),” they noted.

In the current case series an endoscopy revealed significant mucosal inflammation and ulceration in both patients near the time of diagnosis of ICI-associated colitis, without substantial improvement after systemic corticosteroids, anti-TNF, and anti-integrin agents.

However after receiving a FMT both patients had a complete resolution of their colitis. The first patient’s colitis resolved within two weeks following a single FMT treatment; the second patient experienced a partial recovery after the first treatment, followed by complete recovery after a second FMT.

Following treatment the researchers observed marked improvement on endoscopic evaluation, with reduced inflammation and resolution of ulcerations.

Pre- and post-treatment stool analyses revealed patients’ gut microbiomes to be most similar to the donor immediately after treatment, with less resemblance to the donor over time. Post-treatment gut bacteria remained distinct from their own pre-treatment microbiome.

Additionally, distinct new populations of bacterial species were evident in these patients following FMT compared to pre-treatment samples, including several species the researchers said were known to be protective or reduce inflammation.

According to the researchers the cases provided “provocative and novel evidence” that modulation of the gut microbiome via FMT was linked to significant and rapid improvement of refractory ICI-associated colitis.

“The resolution of colitis in these patients can be confirmed clinically and endoscopically after FMT treatment,” Professor Wang said. “Based on these results, this should be evaluated even as a first-line therapy for ICI-associated colitis because it’s safe, quick, and the effect is durable – from one treatment,” she added.

The research team noted that their findings now needed to be confirmed in larger patient populations and a clinical trial setting.