title: Cladribine  tablets for the treatment of relapsing-remitting multiple sclerosis.
abstract: BACKGROUND
  Multiple sclerosis (MS) is a chronic immune-mediated disorder of the central nervous system leading to progressive neurodegeneration and disability. Until 2010, all approved disease-modifying drugs for MS required parenteral administration, which is associated with suboptimal adherence. It was anticipated that new approaches to treatment, including oral agents such as cladribine tablets, may improve adherence. In 2011, the development of cladribine tablets was stopped following negative feedback from the EMA and FDA.
  
  
  METHODS
  This article provides an overview of the chemistry, mechanism of action and pharmacological properties of cladribine tablets therapy, and highlights the rationale for its development as an oral treatment for MS. Key efficacy and safety data from the pivotal Phase III CLARITY study are presented, providing context for the opinion received from the regulatory agencies.
  
  
  CONCLUSIONS
  Despite the promising efficacy data observed in the cladribine tablets clinical trial program, regulatory agencies identified a potential risk of increased malignancies, and raised concerns about the implications of sustained lymphocyte depletion. Following the feedback received from the regulatory agencies, Merck Serono made the decision to withdraw the agent from the regulatory approval process. The experience gained will benefit other research efforts to address the outstanding unmet treatment needs of patients with relapsing MS.
authors.affiliation: University Vita-Salute San Raffaele, Department of Neurology and Institute of Experimental Neurology, Via Olgettina 60, 20132 Milan, Italy. g.comi@hsr.it
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Hartung
authors.forename: Nuwan C
authors.initials: NC
authors.lastname: Kurukulasuriya
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Greenberg
authors.forename: Matthew
authors.initials: M
authors.lastname: Scaramozza
mesh_terms: D000284:Administration, Oral; D017338:Cladribine / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D017326:Clinical Trials, Phase III as Topic; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000188:drug therapy*; D056737:Safety-Based Drug Withdrawals; D013607:Tablets
chemical_list: D007166:Immunosuppressive Agents; D013607:Tablets; D017338:Cladribine