Both doses of cladribine significantly reduced the relapse rate by 55%–58%. In addition, the drug lengthened the time to relapse and decreased the rate of disability progression by approximately one-third.
Cladribine also reduced measures of MS inflammatory activity on MRI brain imaging.
The rate of serious adverse events was 8% with low-dose cladribine and 9% with high-dose cladribine, compared with 6% with placebo. The types of adverse events were similar to those with other immunomodulatory agents: lymphocytopenia, infection, and neoplasms.
Twenty patients had reactivation of latent herpes infections, and 1 had a reactivation of latent tuberculosis that proved fatal. “Cancers were isolated cases across different organ systems, and given the small number, it is not possible to establish a risk for the use of cladribine,” Dr. Giovannoni and his colleagues wrote (N. Engl. J. Med. 2010 Jan. 20 [doi:10.1056/NEJMoa0902533
As with fingolimod, the risks of treatment with cladribine must be carefully weighed against the benefits, and longer follow-up is essential, the investigators added.
All three clinical trials were well conducted and “provide a new horizon for patients with relapsing-remitting MS and a welcome increase in the range of treatment options,” Dr. Carroll noted.
All three first authors and many of their coauthors reported receiving consulting or lecture fees or research support from many manufacturers of drugs for MS, including Biogen Idec, Merck Serono, EMD Serono, and Novartis.