Therapy-related acute leukemia in two patients with multiple sclerosis treated with Mitoxantrone

Two cases of therapy-related acute leukemia (TRAL) after the use of Mitoxantrone for the treatment of secondary progressive multiple sclerosis (MS) are reported. They were extracted from the group of 42 consecutive patients with TRAL diagnosed and treated in single centre between 2000–2010. They were the only two with MS and the only two treated with Mitoxantrone. The first patient was a 43-year-old male with a previous history of MS of 15-year-duration, who developed acute promyelocytic leukemia 9 months following Mitoxantrone therapy (cumulative dose 120 mg). The second patient was a 55-year-old female suffering from MS for 16 years, who developed acute mixed-phenotype leukemia, T/myeloid type, with 46,XX,del(7)(p13)[12]/47,XX,idem,+3/[6]/46,XX[2], 15 months after completion of Mitoxantrone therapy (cumulative dose 100 mg). Acute mixed-phenotype leukemia, T/myeloid type is for the first time described in the context of prior Mitoxantrone therapy. Although the incidence of TRAL in relation to Mitoxantrone pretreatment is rare, we should be vigilant for the prompt identification of this adverse event.