This is a humanized IgG1 monoclonal antibody using the same sequences as the therapeutic antibody teplizumab. It specifically binds to CD3 molecules expressed on the surface of both CD4+ and CD8+ T cells, which are involved in the destruction of pancreatic beta cells. One hypothesis suggests that teplizumab acts as a partial agonist at the T cell receptor (TCR), leading to an increased population of exhausted T cells positive for KLRG1, TIGIT and CD8. These exhausted T cells persist but exhibit impaired effector functions, thereby unlikely to contribute to further β cell destruction. The design incorporates an Fc-non-binding feature aiming to minimize the incidence of cytokine release syndrome (CRS). Teplizumab is indicated to delay the onset of Stage3 type 1 diabetes (T1D) in adults and pediatric patients aged 8 years and older with Stage 2 T1D.