Neoadjuvant immunotherapy for dMMR/MSI-H locally advanced rectal cancer: The future new standard approach?

This is a review of the evidence from studies of the efficacy and tolerability of neoadjuvant immunotherapy for mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI-H) Locally Advanced Rectal Cancer (LARC).For this review, we searched EMBASE and MEDLINE until 22 September 2022. The terms used in the search included mismatch repair-deficient, microsatellite instability, rectal cancer, neoadjuvant and immunotherapy.A total of 92 studies were obtained but only 9 were selected for the final analysis (one prospective and eight retrospective studies), including less than 20 patients per study. Neoadjuvant immunotherapy provides overall response rates of 100% (with and completed clinical response between 40 and 100%).Our review discusses completed prospective and retrospective studies, ongoing clinical trials, and the clinical practice of using neoadjuvant immunotherapy for MSI-H/dMMR LARC. The promising results obtained, would open the door to exploring other alternatives for these patients, offering the possibility of avoiding chemoradiation therapy and surgery in the future.