Paracrine Wnt-Beta-Catenin Signaling Inhibition As A Strategy To Enhance The Efficacy Of Anti-Pd-1 Antibody (Ab) Therapy In A Transgenic Model Of Melanoma.

3053Background: Activation of the Wnt-β-catenin signaling pathway is associated with poor T cell infiltration of tumors. We have previously demonstrated that paracrine Wnt5a-β-catenin signaling is a critical trigger of dendritic cell (DC) tolerization and regulatory T cell (Treg) differentiation in the melanoma microenvironment. In a transgenic BRAFV600EPTEN-/- model, the genetic silencing of melanoma-derived Wnt5a potently enhances infiltrating CD8+T cell effector function and promotes responses to anti-PD-1 Ab therapy. Ipafricept (IPA) is a recombinant Wnt decoy receptor and Vantictumab (VAN) is a Fzd receptor monoclonal Ab. Both molecules inhibit Wnt-β-catenin signaling and have been well-tolerated in ongoing phase I/Ib clinical trials. We explored the ability of IPA/VAN to reverse tumor-mediated immune tolerance and enhance the efficacy of anti-PD-1 Ab immunotherapy in a pre-clinical model that closely recapitulates human melanoma. Methods: Both IPA and VAN were utilized to investigate Wnt-β-catenin i...