Development and non-clinical characterization of Procizumab (invobenitug): a humanized antibody neutralizing circulating DPP3

Dipeptidyl peptidase 3 (DPP3) is an intracellular protein involved in cellular antioxidant responses. Upon acute stress and tissue damage, DPP3 is released into the circulation (circulating DPP3, cDPP3), where it induces vascular, cardiac, and immune dysregulation. Elevated cDPP3 levels have been implicated in multiple organ dysfunction during circulatory failure. Here, we describe the development and characterization of Procizumab (PCZ), a human immunoglobulin (Ig) G1 kappa monoclonal antibody targeting human cDPP3. The murine variant (mAb1967) was generated by immunizing BALB/c mice with a DPP3-derived peptide mimicking an exposed loop of human DPP3 and conjugated to bovine serum albumin. The humanized recombinant antibody was produced by complementarity-determining region grafting into a human framework, expressed in Chinese hamster ovary cells and purified. Binding kinetics and affinity of PCZ for human DPP3 were assessed by biolayer interferometry. The lack of Fc-mediated immune effector functions, including antibody-dependent cellular cytotoxicity, phagocytosis, and complement-dependent cytotoxicity, was demonstrated in human peripheral blood mononuclear cells. Potential cross-reactivity and specificity were evaluated using a human cell microarray assay. In vivo validation was performed in Dpp3 knock-out mice. Pharmacokinetics and tissue distribution of PCZ were assessed by quantitative whole-body autoradiography in male and female Wistar rats administered radio-labeled antibody. Finally, dose-range finding studies evaluating PCZ efficacy and safety were conducted in an acute cardiac dysfunction mouse model. Inhibition of circulating DPP3 activity represents a novel therapeutic approach for the treatment of shock, and PCZ is currently under investigation in clinical studies.