Begelomab is a murine (mouse) monoclonal antibody (typically IgG2b isotype) that specifically targets the Dipeptidyl Peptidase 4 (DPP4) receptor. It acts as an antagonist by binding to its target on the surface of T cells. This binding inhibits T-cell activation, proliferation, and most importantly, T-cell migration into tissues. Begelomab has been primarily investigated as an immunomodulatory agent for the treatment of severe, steroid-refractory acute Graft-versus-Host Disease (GvHD), a life-threatening complication following allogeneic hematopoietic stem cell transplantation (HSCT). By preventing the trafficking of pathogenic T cells, Begelomab aims to reduce GvHD-related tissue damage in the gut and skin.