Immune checkpoint blockade (ICB) therapies, such as anti-PD-1, have transformed cancer treatment, but many patients do not respond due to a non-inflammatory tumor microenvironment (TME). Here, we investigated the impact of targeting Atypical Chemokine Receptor 2 (ACKR2), which scavenges key chemokines involved in immune cell recruitment, on the improvement of anti-PD-1-based therapy. In a melanoma mouse model, we demonstrated that Ackr2 inhibition increases the release of proinflammatory chemokines CCL5 and CXCL10 and enhances the infiltration of NK cells, activated CD8+ and CD4+ effector T cells while reducing regulatory T cells (Tregs) in the TME. Targeting Ackr2 led to tumor growth inhibition, improved survival, and enhanced response to anti-PD-1 therapy. In BRAF- and NRAS-mutant melanoma patients, low ACKR2 expression or high CCL5/CXCL10 levels correlated with improved survival and higher CD8+ T cell markers. Targeting ACKR2 represents a promising approach for developing combination therapies, particularly for 'cold' ICB resistant tumors.
Keywords: ACKR2; CCL5; Cancer immunotherapy; D6; anti-PD-1; combination immunotherapy; immune cell infiltration; immune checkpoint blockade; inflammatory chemokines; melanoma; scavenger receptor; tumor microenvironment.