Immunotherapy for brain cancer: recent progress and future promise

Immunotherapy is emerging as the newest pillar of cancer treatment, with the potential to assume a place alongside surgical debulking, radiotherapy, and chemotherapy. Early experiences with antitumor vaccines demonstrated the feasibility and potential efficacy of this approach, and newer agents, such as immune checkpoint blocking antibodies and modern vaccine platforms, have ushered in a new era. These efforts are headlined by work in melanoma, prostate cancer, and renal cell carcinoma; however, substantial progress has been achieved in a variety of other cancers, including high-grade gliomas. A recurrent theme of this work is that immunotherapy is not a one-size-fits-all solution. Rather, dynamic, tumor-specific interactions within the tumor microenvironment continually shape the immunologic balance between tumor elimination and escape. High-grade gliomas are a particularly fascinating example. These aggressive, universally fatal tumors are highly resistant to radiotherapy and chemotherapy and inevitably recur after surgical resection. Located in the immune-privileged central nervous system, high-grade gliomas also use an array of defenses that serve as direct impediments to immune attack. Despite these challenges, vaccines have shown activity against high-grade gliomas, and anecdotal, preclinical, and early clinical data bolster the notion that durable remission is possible with immunotherapy. Realizing this potential, however, will require an approach tailored to the unique aspects of glioma biology.