Cancer immunotherapy in patients with brain metastases.

The exclusion of "real-world" patients from registration clinical trials of cancer immunotherapy represents a significant emerging issue. For instance, a large fraction of cancer patients develops brain metastases during the course of the disease, but results from large prospective clinical trials investigating this considerable proportion of the cancer patient population are currently lacking. To provide a useful tool for the clinician in a "real-world" setting, we have reviewed the available literature regarding the safety and efficacy of immune check-point inhibitors in patients with cancer metastatic to the brain. Overall, these data provide encouraging evidence that these therapeutic agents can induce intracranial objective responses, particularly in patients with asymptomatic and previously untreated brain metastases. Larger prospective studies are needed to confirm these initial results.