Anti-Human KLRG1 Monoclonal Antibody (Ulviprubart)

Ulviprubart is a humanized, non-fucosylated monoclonal antibody that targets KLRG1 (killer cell lectin-like receptor G1). Its core mechanism involves specifically binding to and depleting terminally differentiated effector memory T cells (TEM/TEMRA) that highly express KLRG1, while preserving naïve T cells, regulatory T cells, and B cells, thereby precisely eliminating pathogenic autoreactive T cells. In clinical practice, Ulviprubart is primarily being developed for the treatment of inclusion body myositis (IBM) and T-cell large granular lymphocytic leukemia (T-LGLL). Although the Phase II/III MUSCLE trial in IBM did not meet its primary endpoint, a trend toward delayed disease progression was observed in the subgroup of patients with mild-to-moderate disease. In T-LGLL, a Phase I study demonstrated a response rate of 53% in those with neutropenia and 22% in those with anemia. The clinical significance of Ulviprubart lies in being the first agent to achieve selective targeting of highly differentiated cytotoxic T cells, offering a novel therapeutic strategy for T-cell-mediated diseases that are refractory to conventional immunosuppression, while further work is needed to identify the optimal patient population who would derive the greatest benefit.