Acute promyelocytic leukemia after mitoxantrone therapy for multiple sclerosis.

Mitoxantrone is a DNA-topoisomerase 2 inhibitor used as a single agent for treatment of relapsing-remitting or progressive multiple sclerosis (MS). We present here two patients treated with mitoxantrone for MS who subsequently developed acute promyelocytic leukemia (APL). These constitute, to our knowledge, the eighth and ninth reports of APL in patients treated with mitoxantrone for MS. Topoisomerase 2 inhibitors are associated with therapy-related acute myeloid leukemia (t-AML) with 11q23 abnormalities, but therapy-related APL (t-APL) is less common, and documentation of nine cases of t-APL after mitoxantrone therapy for MS suggests a specific association.