Long-term immune-related adverse events after discontinuation of immunotherapy

Immune checkpoint inhibitors have revolutionized the treatment of various cancers but are notorious for their potential to cause severe side effects. While most side effects occur during ongoing therapy, an increasing number of reports of late onset have emerged. It is also not yet clear how long side effects can last. Resolution is achieved under symptomatic therapy, but the side effects may persist latently. We present a patient case with recurrence of colitis after closure of an ileostomy over 1 year after discontinuation of immune checkpoint inhibitor therapy with nivolumab and ipilimumab. To the best of our knowledge, no other case with severe colitis still lasting after more than a year of suspension of therapy has yet been reported.