Inhibition of the NKG2A immune checkpoint restores natural killer cell and T cell effector function in preclinical cancer models. In addition, NKG2A blockade in combination with other therapeutic antibodies is showing encouraging responses in a subset of patients with metastatic colorectal or head and neck cancer. However, established biomarkers of response are lacking, and larger trials are needed to enable firm conclusions to be drawn about whether NKG2A inhibition complements existing immunotherapies.