Glioblastoma and Immune Checkpoint Inhibitors: A Glance at Available Treatment Options and Future Directions

Abstract

Glioblastoma is known to be one of the most aggressive and fatal human cancers, with a poor prognosis and resistance to standard treatments. In the last few years, many solid tumor treatments have been revolutionized with the help of immunotherapy. However, this type of treatment has failed to improve the results in glioblastoma patients. Effective immunotherapeutic strategies may be developed after understanding how glioblastoma achieves tumor-mediated immune suppression in both local and systemic landscapes. Biomarkers may help identify patients most likely to benefit from this type of treatment. In this review, we discuss the use of immunotherapy in glioblastoma, with an emphasis on immune checkpoint inhibitors and the factors that influence clinical response. A Pubmed data search was performed for all existing information regarding immune checkpoint inhibitors used for the treatment of glioblastoma. All data evaluating the ongoing clinical trials involving the use of ICIs either as monotherapy or in combination with other drugs was compiled and analyzed.

Keywords: blood-brain barrier; glioblastoma; immune checkpoint inhibitors; immunosuppression; tumor microenvironment.

Figure 1

The interaction between PD-1 expressed on the surface of T cells, and PD-L1 expressed on the surface of tumor cells. The immunological checkpoint prevents T-cell activation.

Figure 2

Immune checkpoint inhibitors (ICIs) target T cell exhaustion by blocking immune checkpoints PD-1 and PD-L1, restoring T cell function and antitumor activity.