It has previously been shown that a fraction of patients treated with anti-PD-1 are prone to develop immune-related adverse events (irAEs) such as colitis and particularly when anti-PD-1 is combined with other immune checkpoint inhibitors such as anti-CTLA-4.50 However, no signs of irAEs including gut inflammation were observed in any of our treatment groups. The gene discussed is CTLA4; the disease is colitis.