A study of therapy-related acute leukaemia after mitoxantrone therapy for multiple sclerosis

To evaluate the incidence of therapy-related acute leukaemia (t-AL) after single-agent mitoxantrone (MITO) treatment we reviewed medical records of patients in three studies of single-agent MITO therapy for multiple sclerosis (MS) and existing literature on MITO therapy in MS, leukaemia, and solid tumors. Of 1378 MITO recipients in the three MS studies (mean cumulative dose of 60 mg/m(2) and mean follow-up of 36 months), one patient had t-AL, an observed incidence proportion of 0.07% [95% confidence interval (0)=0.00-0.40%]. There were no cases of t-AL in published reports of nine additional studies of single-agent MITO therapy for MS. There was one published case report of acute promyelocytic leukaemia detected five years after initiating MITO therapy for MS. The observed incidence proportion of t-AL is very low in patients who received MITO as single-agent therapy for MS. Although these observations provide preliminary reassurance, extended follow-up of these patients and those who receive higher cumulative doses of MITO is required to define the long-term risk of t-AL after MITO therapy for MS.