Results and challenges of immune checkpoint inhibitors in colorectal cancer.

As of now, dMMR and POLE mutations (DNA polymerase ε) with ultramutator phenotype are the most powerful predictive biomarkers of CPI efficacy. The most challenging issue is pMMR mCRC and determination of how to convert a 'nonimmunogenic' neoplasm into an 'immunogenic' neoplasm, a combination of CPIs with radiation or MEK inhibitor probably being the most relevant strategy. Next-generation sequencing (NGS) assays to quantify mutational load could be more reliable predictive biomarkers of CPIs efficacy than PD-L1 expression or immune scores.