Definition

A T-cell-engaging, humanized, Fc-silenced immunoglobulin G1 (IgG1)-based bispecific antibody directed against both the tumor-associated antigen (TAA) FLT3 tyrosine kinase receptor (Fms-like tyrosine kinase 3; FLT3; FLT-3; CD135; fetal liver kinase-2; FLK2) and the CD3 antigen found on T lymphocytes, with potential immunostimulating and antineoplastic activities. Upon administration, anti-FLT3/CD3 bispecific antibody CLN-049 binds to both CD3 on cytotoxic T lymphocytes (CTLs) and FLT3 found on FLT3-expressing tumor cells. This activates and redirects CTLs to FLT3-expressing tumor cells, which results in the CTL-mediated cell death of FLT3-expressing tumor cells. FLT3, a cytokine receptor belonging to the class III tyrosine kinase receptors, is overexpressed or mutated in most B-lineage and acute myeloid leukemias (AMLs).