Disruption of the structural maintenance of chromosomes 5/6 complex enables tumor mutagenesis.
Summary
The SMC5/6 complex is crucial for genome stability, with germline variants linked to genomic instability. This pan-cancer analysis demonstrates that deleterious somatic variants in SMC5/6 genes, but not copy number alterations, are associated with an elevated tumor mutational burden (TMB). This mutagenesis is largely attributed to polymerase epsilon dysfunction and mismatch repair deficiency. Patients with these SMC5/6 variants exhibit improved survival, partly due to a superior response to immunotherapy. These findings indicate that SMC5/6 gene status could serve as a prognostic and predictive biomarker for tailored therapeutic strategies.
Analysis
This study is significant as it identifies the SMC5/6 complex as a novel regulator of genomic stability, whose somatic disruption in cancers has major clinical implications. The correlation between deleterious SMC5/6 variants, elevated TMB, and improved response to immunotherapy provides a new avenue for patient stratification. This could enable better targeting of therapies and improved outcomes for patients with various cancer types, by using SMC5/6 status as a predictive biomarker for immunotherapy response.