Genomic Predictors of Response to Immune Checkpoint Inhibitors
Immune checkpoint inhibition therapy is now a mainstay of oncology, remarkably improving survival for some patients. Predicting which patients will benefit most remains an open challenge, however. Several biomarkers have been approved by the FDA for use as companion diagnostics to various ICI agents and in various clinical settings. These include immunohistochemistry for PD-L1, microsatellite instability (MSI), and tumor mutation burden (TMB). While the PD-L1 biomarker can be assessed by a variety of laboratory methods, MSI and TMB is deployed in the setting of comprehensive genomic profiling, made possible by next generation sequencing. The relationship between these biomarkers and the predictive value of each will be explored in this lecture, which will hopefully enable the practicing pathologist to help inform test selection when called upon by oncology colleagues.
