| Checkpoint inhibitor induced colitis | |
|---|---|
| Specialty | Gastroenterology |
| Symptoms | Diarrhea, abdominal pain, rectal bleeding |
| Complications | Perforation, toxic megacolon |
| Usual onset | ~6-7 weeks after starting checkpoint inhibitor[1] |
| Causes | Cancer immunotherapy treatment |
| Risk factors | Caucasian, NSAID use, anti-CTLA4 treatment, melanoma, history of prior checkpoint inhibitor induced colitis, Faecalibacterium in fecal microbiota |
| Diagnostic method | Colonoscopy, stool tests for infection |
| Differential diagnosis | Infectious colitis, gastrointestinal metastases (rare) |
| Prevention | None |
| Treatment | Corticosteroids, infliximab, vedolizumab |
| Prognosis | Associated with improved overall survival |
| Frequency | 0.7 – 1.6% (anti-PD1) 5.7 – 9.1% (anti-CTLA-4) 13.6% (combination therapy) |
Checkpoint inhibitor induced colitis is an inflammatory condition affecting the colon (colitis), which is caused by cancer immunotherapy (checkpoint inhibitor therapy). Symptoms typically consist of diarrhea, abdominal pain and rectal bleeding. Less commonly, nausea and vomiting may occur, which may suggest the present of gastroenteritis. The severity of diarrhea and colitis are graded based on the frequency of bowel movements and symptoms of colitis, respectively.
The gold standard for the diagnosis of checkpoint inhibitor induced colitis is colonoscopy with evaluation of the terminal ileum. However, in most cases, a flexible sigmoidoscopy is sufficient. Infection should be ruled out with stool studies, including Clostridioides difficile, bacterial culture, ova and parasites. Symptoms of upper abdominal pain, nausea or vomiting warrant evaluation with upper endoscopy.
Treatment of immune checkpoint inhibitor colitis is based on severity, as defined by the grade of diarrhea and colitis. Mild cases by managed with temporary interruption of immune checkpoint inhibitor therapy, dietary modification (low residue), and/or loperamide. More severe cases require immune suppression with corticosteroid therapy. If steroids are ineffective, infliximab may be considered. If colitis fails to improve with infliximab, then vedolizumab may be effective.