The advent of immune checkpoint inhibition for the treatment of patients with primary advanced or recurrent dMMR/MSI high endometrial cancer in 2025.

Abstract

The Cancer Genome Atlas identified four distinct molecular subtypes of endometrial cancer (EC): POLE mutated, mismatch repair deficient (dMMR), copy number low, and copy number high. The goal of this review is to summarize the profound clinical implications of molecular subtyping, particularly in guiding treatment decisions for dMMR and microsatellite instability high (MSI-H) EC. Clinical trials have demonstrated the remarkable efficacy of immunotherapy in dMMR/MSI-H EC tumors. Trials including GARNET, KEYNOTE-158, NRG GY-018, and RUBY have shown significant improvements in clinical outcomes for patients with advanced and recurrent disease, leading to FDA approvals for immunotherapy in both frontline and recurrent EC treatment settings.Building on these successes, recent studies, including DUO-E, are exploring combination therapies to enhance the efficacy of immunotherapy in EC. Simultaneously, trials including NRG GY-020, are investigating the potential benefits of immunotherapy in early-stage disease. Immunotherapy therapy has revolutionized the treatment of endometrial cancer in both upfront and recurrent settings, with molecular subtyping identifying patients most likely to benefit, especially those with dMMR/MSI-H tumors.