Bacteroidetes phylum may be protective for development of colitis in melanoma patients treated with ipilimumab (75).Faecalibacterium may be predictive of colitis in melanoma patients treated with ipilimumab (74).Bacteroides intestinalis is associated with ≥ grade 3 colitis in patients with melanoma treated with combined ipilimumab and PD-1 blockade (96). The gene discussed is PDCD1; the disease is melanoma.