20D9-ADC

20D9-ADC is a **novel antibody-drug conjugate (ADC)** targeting FLT3 (Fms-like tyrosine kinase 3), a receptor frequently mutated or overexpressed in acute myeloid leukemia (AML)[1][5][7]. The antibody portion of 20D9-ADC recognizes FLT3, including the pathogenic FLT3-ITD mutation found in many AML patients[1][3][5][7]. The ADC is constructed by conjugating the 20D9 antibody (engineered on a human IgG1 backbone) with the cytotoxic payload MMAF, a tubulin inhibitor, via the P5 conjugation technology[1][5][7]. Mechanistically, 20D9-ADC **binds to FLT3-positive leukemic cells, is internalized, and releases MMAF**, leading to selective cytotoxicity against FLT3+ cancer cells with limited effect on healthy hematopoietic cells[1][5][7]. Preclinical studies showed strong in vitro and in vivo antileukemic activity, including in FLT3-ITD–positive cell lines, AML patient-derived xenograft models, and significant synergy when combined with the FLT3 inhibitor midostaurin without notable hematotoxicity[1][3][5][7][9]. The drug was developed by Ludwig-Maximilians-Universität München and collaborators[1][5][7].