Leukemia Therapy Offers Hope to Multiple Sclerosis Patients

Multiple sclerosis (MS) is an autoimmune disorder that damages the central nervous system. The most common form of MS, known as relapsing-remitting, afflicts approximately 85% of MS patients (1). This type of MS involves a "flare-up" of symptoms followed by recovery, or remission. Common symptoms are vision problems, numbness, and difficulties with coordination and balance.

A new study published in The New England Journal of Medicine assessed the use of cladribine, an immunosuppressive drug approved for use in leukemia therapy, for treating relapsing-remitting MS (2). Interestingly, this is one of three studies published back-to-back addressing oral therapies for MS (2, 3, 4). The other two phase III trials characterized the immunomodulatory drug fingolimod. This is significant because there are no current oral therapies approved for use in MS, only injectables.

The cladribine study was a double blind and placebo controlled phase III clinical trial. The goal of the work was to evaluate the effect cladribine on the relapse rate in relapsing-remitting MS patients after 96 weeks under the author's treatment scheme. 1,326 patients were enrolled in the study and randomized based upon demographic information, severity of MS, and previous therapy into in a placebo group or into high or low dose cladribine treatment group. After the first 48 weeks of the trial, both treated groups received the same dose of cladribine up to week 96.

Cladribine treatment groups had a relapse rate of 0.14 and 0.15 for the low and high treatment groups respectively. The relapse rate in the placebo group was 0.33, approximately double the rate in either treatment group. While 60% of the placebo treatment group did remain relapse free throughout the study, nearly 80% of those in the treatment groups were relapse free. Cladribine treatment also delayed the time to the first relapse for patients who did experience them and decreased the total number of relapses experienced. The data presented by the authors suggests that cladribine is effective in both preventing relapses and keeping patients relapse free for an extended period of time.

The most common adverse event reported in the cladribine treatment group was lymphocytopenia, which is a reduction in white blood cells. This may leave some individuals prone to infection when treated with the drug. However, benefits may outweigh risks in preventing MS relapses with cladbridine. As stated earlier, this work is significant in that it demonstrates an oral therapy for MS is effective. The study was published back-to-back with two other phase III clinical trials characterizing fingolimod, another potential oral therapy for MS.

References:

National Multiple Sclerosis Society. For people with relapsing MS. http://www.nationalmssociety.org/about-multiple-sclerosis/relapsing-ms/index.aspx. Accessed 1/26/2010.
Giovannoni, G. A Placebo-Controlled Trial of Oral Cladribine for Relapsing Multiple Sclerosis N Engl J Med. 2010 Jan 20. [Epub ahead of print].
Kappos, L. A Placebo-Controlled Trial of Oral Fingolimod in Relapsing Multiple Sclerosis. N Engl J Med. 2010 Jan 20. [Epub ahead of print].

Cohen, JA. Oral Fingolimod or Intramuscular Interferon for Relapsing Multiple Sclerosis. N Engl J Med. 2010 Jan 20. [Epub ahead of print].