The role of immune checkpoint inhibitors for patients with advanced stage microsatellite stable colorectal cancer and high tumor mutation burden: quantity or quality?

Introduction: The US Food and Drug Administration (FDA) approved pembrolizumab for patients with unresectable or metastatic solid tumors with tumor mutational burden (TMB) of ≥ 10 mutations/megabase. However, the clinical implications of this universal cutoff of TMB ≥ 10 for patients with microsatellite stable (MSS) metastatic colorectal cancer (CRC) remain debatable.

Areas Covered: In this review, we discuss the tissue agnostic approval of pembrolizumab, its efficacy, and clinical relevance in the management of patients with MSS CRC patients with high TMB (defined as TMB ≥ 10).