FORMYXAN (Mitoxantrone) is a medication that works by suppressing the immune system to lessen its attack on the myelin sheath that surrounds the nerves. It can decrease the increase in disability and reduce the relapse rate in people with the possibility of relapsing-remitting, relapsing-progressive, and progressive-secondary Multiple Sclerosis. It can also treat prostate cancer and certain types of leukemia, such as acute non-lymphocytic leukemia.