Cladribine: An Investigational immunomodulatory agent for multiple sclerosis

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and safety of cladribine, a purine analog undergoing Phase III trials for approval of its use in the treatment of multiple sclerosis (MS). DATA SOURCES: A MEDLINE search (1966-September 2006) was conducted using the key words cladribine and multiple sclerosis. No limits were placed on the search. STUDY SELECTION AND DATA EXTRACTION: Studies and review articles related to cladribine and MS were reviewed. The trials examining the role of cladribine in MS were analyzed. DATA SYNTHESIS: Cladribine is a purine analog that demonstrates lymphocytotoxic activity. Recent data suggest that cladribine may have a role in the treatment of relapsing-remitting and the progressive forms of MS. In these studies, cladribine has shown mixed results in decreasing neurologic disability, as measured by various rating scales, but has consistently shown positive results in reducing the number of enhancing lesions, which reflects a measure of disease activity. To date, there is one ongoing study examining the role of oral cladribine in the treatment of relapsing-remitting MS. The incidence of adverse effects with cladribine has been significantly greater than with placebo, with the most common being myelosuppression. CONCLUSIONS: While data do not support its use as a first-line MS treatment, cladribine may be a promising agent for refractory patients with secondary progressive MS. Further studies are warranted.