Pediatric Rectal Adenocarcinoma With Mismatch Repair Deficiency Responds to Immunotherapy

Case Study

Comprehensive genomic profiling (CGP), including germline testing for cancer predisposition genes (CPGs), can be used in cancer treatment and prevention. Herein, we report a 6-year-old boy with rectal adenocarcinoma presenting with molecular features of MMR deficiency, including MSI-high and TMB-high status. We describe the workup for a possible CPS and his response to combination therapy with nivolumab and ipilimumab.