Brain metastases account for considerable morbidity and mortality in patients with
cancer. Despite increasing prevalence, limited therapeutic options exist. Recent advances in our understanding of the molecular and cellular underpinnings of the
tumor immune microenvironment and the immune evasive mechanisms employed by
tumor cells have shed light on how
immunotherapies may provide therapeutic benefit to patients. The development and evolution of
immunotherapy continue to show promise for the treatment of
brain metastases. Positive outcomes have been observed in several studies evaluating the efficacy and safety of these treatments. However, many challenges persist in the application of
immunotherapies to
brain metastases. This review discusses the potential benefits and challenges in the development and use of checkpoint inhibitors,
chimeric antigen receptor T-cell
therapy, and oncolytic viruses for the treatment of
brain metastases. Future studies are necessary to further evaluate and assess the potential use of each of these
therapies in this setting. As we gain more knowledge regarding the role
immunotherapies may play in the treatment of
brain metastases, it is important to consider how these treatments may guide clinical decision making for clinicians and the impact they may have on patients. IMPLICATIONS FOR PRACTICE:
Immunotherapies have produced clinically significant outcomes in early clinical trials evaluating patients with
brain metastases or demonstrated promising results in preclinical models. Checkpoint inhibitors have been the most common
immunotherapy studied to date in the setting of
brain metastases, but novel approaches that can harness the immune system to contain and eliminate
cancer cells are currently under investigation and may soon become more common in the clinical setting. An understanding of these evolving
therapies may be useful in determining how the future management and treatment of
brain metastases among patients with
cancer will continue to advance.