Biomarkers of immunotherapy response in neuro-oncology.

While immunotherapy has shown significant promise for many cancers, its translation into the treatment of brain tumors has been limited. While several immunotherapy trials have been negative in brain cancer, these studies have identified a subset of responders which has generated considerable excitement for the future of the field. In this review, we summarize promising immunotherapy response biomarkers for CNS tumors with a focus on brain metastases, glioblastoma, and meningioma. The potential value of genomic, transcriptomic, cellular, proteomic, radiologic, and liquid biopsy approaches are discussed in a tumor-specific fashion. We emphasize the need to validate and expand upon each of these purported biomarkers. Disease-specific immunotherapy response biomarkers may potentially lead to more efficacious clinical trial designs, ultimately leading to new treatment options for a subset of patients.