Popular MS Drug Raises Leukemia Risk

The risk of developing leukemia as a side effect of a drug for multiple sclerosis (MS) is higher than previously reported. Mitoxantrone is an immunosuppressant drug approved by the FDA for treatment of several forms of advancing MS. It is one of only two drugs that has been shown to benefit people with secondary progressive MS who are having attacks. However, the drug can cause heart damage at high total doses. Due to this, the lifetime cumulative dose is equal to about eight to 12 doses over two to three years.

Previous studies have also shown that the people with MS treated with the drug have an increased risk of developing leukemia. Those studies showed that acute leukemia occurred in .07 percent to .25 percent of MS patients taking mitoxantrone. Today's retrospective study of 2,854 Italian people with MS receiving the drug found that leukemia occurred in .74 percent.

"This rate is significantly higher than what has been previously reported," said study author Vittorio Martinelli, MD, of University Vita-Salute in Milan, Italy. "The potential risk of leukemia should be carefully considered against the potential benefits of mitoxantrone treatment on every single patient."