Roas et al. [53] identified the anti-FLT3 antibody 20D9 from hybridoma cells of immunized rats and mice as the most specific and active against mutated FLT3 leukemic cell lines (Ba/F3 and MOLM-13) and subsequently conjugated it with the inhibitor of tubulin polymerization, monomethyl auristatine F. The corresponding antibody drug conjugate (ADC) 20D9, thus obtained, confirmed selective efficacy both in murine and human FLT3mut cell lines and in AML-PDX murine model, with irrelevant activity in cultures of normal CD34+ progenitor cells. Here, CD34 is linked to acute myeloid leukemia.