Combined blockade of VEGF, Angiopoietin-2, and PD1 reprograms glioblastoma endothelial cells into quasi-antigen-presenting cells

Glioblastoma (GBM) remains a highly aggressive and uniformly fatal primary tumor, which resists cytotoxic, targeted, antiangiogenic, and immune therapies, even when used in combination. Here we report that tumor endothelial cell dysfunction confers resistance to immunotherapy in preclinical GBM models. Anti-VEGF-therapy-induced vascular normalization is insufficient to fully restore the endothelial cell function. Strikingly, concomitant blockade of Ang2, VEGF, and PD1 reprograms dysfunctional endothelial cells to quasi-antigen presenting cells and upregulates receptors required for cytotoxic T lymphocyte entry into the tumor. Blocking VEGF, Ang2, and PD1 induces durable anti-tumor T cell responses. Upregulation of the transcription factor T-bet is both necessary and sufficient for generating resident memory T cells elicited by this combination therapy. In summary, our study reveals the role of Ang2 in resistance to PD1-blockade and provides a compelling rationale for clinical evaluation of blocking Ang2 along with VEGF and PD1 in GBM patients. Statement of Significance Our study is the first to demonstrate Ang2 as a resistance pathway for both αVEGF and αPD1 in GBM. Concomitant blockade of Ang2 reprograms endothelial cells to recruit, activate and retain CD8 T cells, overcomes resistance to αVEGF and αPD1, and imparts T cell memory formation via T-bet in GBM.