We describe the up-regulation of an adaptive immunosuppressive pathway during antiangiogenic therapy, by which PD-L1 (programmed cell death ligand 1), the ligand of the negative immune checkpoint regulator PD-1 (programmed cell death protein 1), is enhanced by interferon-γ-expressing T cells in distinct intratumoral cell types in refractory pancreatic, breast, and brain tumor mouse models.
The aims of this study were to assess the association of two single nucleotide polymorphisms in the PD-1 gene, PD-1.5 (+7785 C/T-rs2227981) and PD-1.3 (+7146 G/A- rs11568821), with benign and malignant brain tumors.
While PD-1 expression has been widely investigated, its role in CD4+ effector T cells in the setting of health and cancer remains unclear, particularly in the setting of glioblastoma multiforme (GBM), the most aggressive and common form of brain cancer.
These findings suggest that the neoadjuvant administration of PD-1 blockade enhances both the local and systemic antitumor immune response and may represent a more efficacious approach to the treatment of this uniformly lethal brain tumor.
Recent studies with immunomodulatory agents targeting both cytotoxic T-lymphocyte protein 4 (CTLA4) and programmed cell death 1 (PD1)/programmed cell death ligand 1 (PDL1) have shown to be very effective in several cancers revealing an unexpected great activity in patients with both primary and metastatic brain tumors.