Tuberculosis reactivation at ileum following immune checkpoint inhibition with pembrolizumab for metastatic nasopharyngeal carcinoma: a case report

BACKGROUND: Tuberculosis (TB) reactivation has been increasingly identified following immune checkpoint inhibitor (ICI) therapy for cancer patients. However there has been no report on TB reactivation in the gastrointestinal tract. In the report, we describe a patient who developed TB ileitis after pembrolizumab for her metastatic nasopharyngeal carcinoma (NPC). Rechallenge with pembrolizumab after its temporary interruption together with anti-TB therapy produced continuous tumor response but without further TB reactivation. CASE PRESENTATION: A 29-year-old lady with metastatic NPC involving the cervical nodes, lungs and bones started pembrolizumab after failure to multiple lines of chemotherapy. She complained of sudden onset of abdominal pain, vomiting and bloody diarrhea with mucus 21 months after pembrolizumab. Colonoscopy revealed terminal ileitis with multiple caseating granulomas with Langerhan cells. Serum interferon gamma release assay was strongly positive. She was treated with anti-TB medication and was later rechallenged with pembrolizumab for her progressive lung metastases without further TB relapse while her lung metastases were brought under control again. CONCLUSION: To date, this is the first gastrointestinal TB reactivation after ICI therapy for cancer. Guidelines to screen for TB before initiation of ICIs in endemic areas should be established.