A multi-faceted discovery strategy identifies functional Dickkopf-1 antibodies binding to cysteine-rich domain 1 of hDKK1 for cancer immunotherapy via Wnt non-canonical pathway 2061

Abstract Description Wnt signaling plays an important role in embryonic development and tumorigenesis. These biological effects can be exerted by activation of Wnt canonical or pathway or non-canonical pathway, and regulation of a set of downstream genes. DKK1 is a potent inhibitor of Wnt signaling via competing with Wnt binding to the LRP5/6 co-receptors. DKK1 is tumorigenic in multiple cancer types and immunosuppressive via MDSCs and NK cells. DKK1 has become a promising target for cancer immunotherapy. In this study, we created phage display libraries and machine learning models for optimal discovery. We discovered anti-DKK1 antibodies blocking the binding of DKK1 to the co-receptors. Binding of the antibodies to different cysteine-rich domains (CRDs) of hDKK1 leads to different activation effects. The in vitro functional assays showed the interaction of Wnt canonical pathway was restored in the presence of anti-DKK1 antibodies binding to DKK1 C-terminal CRD2, resulting in upregulating Wnt canonical TCF/LEF signaling and reactivating osteoblast differentiation. Moreover, anti-DKK1 antibodies binding to DKK1 N-terminal CRD1 induced Wnt non-canonical JNK phosphorylation, immune cell activation and led to tumor cell cytotoxicity. In vivo studies indicated that anti-DKK1 antibody leads are potent in tumor regression and may have promising efficacy as a cancer immunotherapy via activating Wnt non-canonical pathway. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)