Faecal microbiota transplantation for immune checkpoint inhibitor-induced colitis is safe and contributes to recovery: two case reports

Immune checkpoint inhibitors (ICIs) have improved the prognosis in multiple cancer types. However, ICIs can induce immune-related adverse events such as immune-mediated enterocolitis (IMC). The gut microbiota may be implicated in IMC development. Therefore, we investigated faecal microbiota transplantation (FMT) as treatment option for two patients with metastatic cancer suffering from refractory IMC. The patients were treated with respectively one and three FMTs after vancomycin pre-treatment. We monitored defaecation frequency, faecal calprotectin, and microbiota composition. After FMT, both patients improved in defaecation frequency, were discharged from the hospital, and received lower dosage of immunosuppressive therapy. Patient one developed an invasive pulmonary aspergillosis deemed to be related to prolonged steroid exposure. Patient two suffered from a Campylobacter jejuni infection after the first FMT and was treated with meropenem, resulting in a low-diversity microbiota profile and increased calprotectin levels and defaecation frequency. After a second and third FMT, bacterial diversity increased and defaecation frequency and calprotectin levels decreased. Pre-FMT, both patients showed low bacterial richness, but varying bacterial diversity. After FMT, diversity and richness were similar to healthy donor levels. In conclusion, FMT resulted in improvement of IMC symptoms and corresponding microbial changes in two cancer patients with refractory IMC. While more research is warranted, microbiome-modulation could be a promising new therapeutic option for IMC.