Novel Biomarkers for Predicting Response to Cancer Immunotherapy

Book excerpt: Immunotherapy has revolutionized the treatment of malignancies. Targeting of immune checkpoints cytotoxic T-lymphocyte-associated protein 4, programmed cell death protein 1 (PD-1) and its ligand (PD-L1) has led to improving survival in a subset of patients. Despite their remarkable success, clinical benefit remains limited to only a subset of patients. A significant limitation behind these current treatment modalities is an irregularity in clinical response, which is especially pronounced among checkpoint inhibition. Currently, relevant predictors of cancer immunotherapy response include microsatellite instability-high/deficient mismatch repair (MSI-H/dMMR), expression of PD-L1, tumor mutation burden (TMB), immune genomic characteristics, and tumor infiltrating lymphocytes (TILs). However, none of them have sufficient evidence to be a stratification factor. Moreover, as the combined strategies for effective cancer immunotherapy had been developed in multiple tumors, such as Immunotherapy combined with chemotherapy, radiotherapy, targeted therapy and anti-angiogenesis therapy. Therefore, the development of novel biomarkers endowed with high sensitivity, specificity and accuracy able to identify which patients may truly benefit from the treatment with cancer immunotherapy would allow to refine the therapeutic selection and to better tailor the treatment strategy.