Novantrone (mitoxantrone) is a powerful medication given in the vein generally every 3 months for up to 2 years.  The medication has been shown to reduce relapses by 68%, prevent new MRI activity by 85%, and reduce the risk of disability progression by 62%. Although very effective, Novantrone has serious risks including leukemia, heart injury, serious infection and permanent loss of menstrual cycle.   The risk of leukemia varies in studies but may be as much as 1 person in 135 treated patients.