Molecular characterization of response to rectal chemoradiation

Pre-operative chemoradiation (CRT) followed by resection is the standard of care option for patients with locally advanced rectal adenocarcinoma. Pathologic downstaging after CRT is associated with improved outcomes, but molecular predictors of response are poorly understood. We performed whole exome sequencing, gene expression profiling, and immune infiltrate analysis on rectal adenocarcinoma tumors prior to neoadjuvant CRT (pre-CRT) and at the time of resection (post-CRT) in 17 patients to identify somatic mutations and derive molecular biomarkers distinguishing complete and excellent partial responders versus non-responders.