A novel myeloid cell line, Marimo, derived from therapy-related acute myeloid leukemia during treatment of essential thrombocythemia: Consistent chromosomal abnormalities and temporary C-MYC gene amplification

A novel myeloid leukemia cell line, Marimo, was established from bone marrow cells of a patient with secondary acute myeloid leukemia (AML) that had developed during the treatment of essential thrombocythemia (ET) with busulfan. Karyotype at the ET phase was 46,XX,der(15)t(1;15) (q23;p12–13), but at the blastic phase changed to 44,XX,−5,de1(8)(q22),add(17)(p11),+18, psu dic(18;9) (q23;p21)x2 lacking t(1;15). In Marimo cells, C-MYCgene was temporarily amplified by double-minutes (dmin) but disappeared at 33 months, whereas t(10;14;11)(q22;q32;q13) and t(10;14)(q22;q32) were added in vitro psu dic(18;9)×2 and add(17)(p11) were consistently found throughout the culture. These results suggest that this AML clone is not derived from ET but rather is therapy-related.