KMT2A and acute myeloid leukemia: However, a 6.7 kb MLL cleavage fragment, identical to that detected when we incubated the haemopoietic cell line BV173 in vitro with 10 μM etoposide for 6 h, was detected in the bone marrow (morphologically <5% blasts and no circulating blast seen) obtained 3 months after HLH diagnosis, 1 month after the last dose of etoposide (cumulative dose: 1.35 g m−2) and 3 months prior to the diagnosis of overt t-AML.