Angiopoietin-2–Dependent Spatial Vascular Destabilization Promotes T-cell Exclusion and Limits Immunotherapy in Melanoma

Abstract

T cell position in the tumor microenvironment determines the probability of target encounter and tumor killing. CD8+ T cell exclusion from the tumor parenchyma is associated with poor response to immunotherapy, and yet the biology that underpins this distinct pattern remains unclear. Here we show that the vascular destabilizing factor angiopoietin-2 (ANGPT2) causes compromised vascular integrity in the tumor periphery, leading to impaired T cell infiltration to the tumor core. The spatial regulation of ANGPT2 in whole tumor cross-sections was analyzed in conjunction with T cell distribution, vascular integrity, and response to immunotherapy in syngeneic murine melanoma models. T cell exclusion was associated with ANGPT2 upregulation and elevated vascular leakage at the periphery of human and murine melanomas. Both pharmacological and genetic blockade of ANGPT2 promoted CD8+ T cell infiltration into the tumor core, exerting antitumor effects. Importantly, the reversal of T cell exclusion following ANGPT2 blockade not only enhanced response to anti-PD-1 immune checkpoint blockade therapy in immunogenic, therapy responsive mouse melanomas, but it also rendered non-responsive tumors susceptible to immunotherapy. Therapeutic response after ANGPT2 blockade, driven by improved CD8+ T cell infiltration to the tumor core, coincided with spatial TIE2 signaling activation and increased vascular integrity at the tumor periphery where endothelial expression of adhesion molecules was reduced. These data highlight ANGPT2/TIE2 signaling as a key mediator of T cell exclusion and a promising target to potentiate immune checkpoint blockade efficacy in melanoma.

Quantitative multiplex immunohistochemistry reveals inter-patient lymphovascular and immune heterogeneity in primary cutaneous melanoma

“…Here, a high density of intratumoral AQP1 + CD34 + αSMA - activated capillaries and postcapillary venules, in particular, indicated a TME favorable for intratumoral T cell infiltration. These observations are consistent with preclinical work that demonstrates that vascular phenotype regulates T cell infiltration ( 14 , 42 ), together suggesting that careful histological analysis of the endothelium in human tumors may be predictive of response to therapy or indicate synergistic therapeutic opportunities ( 11 , 17 ).…”

Tumor Angiocrine Signaling: Novel Targeting Opportunity in Cancer

“…In human and murine melanomas, ANGPT2 upregulation was associated with cytotoxic T-cell exclusion and immune evasion, a phenotype reversed upon pharmacological inhibition of this factor. Interestingly, the blockade of ANGPT2 signaling increased cytotoxic CD8 + T-cell infiltration into the tumor and improved the response to immunotherapy in melanoma mouse models [80]. Similar roles of ANGPT2 in tumor immunosuppression have been reported for non-small cell lung cancer and glioblastoma [81,82].…”

“…The pharmacological inhibition of ETBR promoted T-cell homing to tumors and augmented the effectiveness of cancer vaccines in mouse models [76]. The angiocrine factor angiopoietin-2 (ANGPT2) is secreted by endothelial cells following angiogenic or inflammatory stimuli and has been implicated in immunosuppression [79,80]. ANGPT2 inhibits the cytotoxic role of monocytes by blocking the secretion of TNF-α.…”

Status of alternative angiogenic pathways in glioblastoma resected under and after bevacizumab treatment

“…It is also known that ANGPT2 compensates for VEGF inhibition by recruiting perivascular myeloid-derived suppressive cells and M2 macrophages [ 39 , 40 ]. Upregulation of ANGPT2 is associated with T-cell exclusion, and blocking it promotes CD8+ T-cell infiltration, resulting in anti-tumor effects [ 41 ]. These evidences might support results of a clinical trial for bispecific antibodies targeting VEGF and ANGPT2 [ 42 , 43 ], potentially supporting ANGPT2-targeted therapy combined with anti-VEGF therapy as a second-line therapy for patients with refractoriness of Bev.…”