Abstract
The immune system plays an essential role in the surveillance and eradication of neoplastic cells. This interaction is modulated via immunologic regulators (checkpoints). Antibodies that block the checkpoints cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and the programmed cell death protein 1 pathway (PD1/PD-L1) have demonstrated efficacy in a number of malignancies. However, response rates are variable, and administration of these antibodies can be associated with immune-related adverse events. Therefore, researchers are engaged in an effort to discover biomarkers that may predict response to these agents. This review focuses on potential blood and tumor-based biomarkers that have been assessed in patients treated with these checkpoint-blocking antibodies.