Serono announced has started recruiting US patients into its Phase III trial of oral cladribine for the treatment of multiple sclerosis, and says the study should complete before the end of the year. By Phil Taylor

The CLARITY study (CLAdRIbine Tablets in Treating MS OrallY Study) kicked off outside the USA last year, and is now being expanded to include 17 US clinical trial sites. It is designed to assess the effect of oral cladribine on clinical relapses, disability progression and MRI (magnetic resonance imaging) brain activity in around 1,200 patients with the relapsing-remitting form of MS.

Previous clinical trials using cladribine administered by injection in patients with MS showed positive effects in the reduction of new lesion development in the brain as seen on MRI scans, and reductions in relapses were also observed, notes Serono.

The Swiss firm is in a race to bring the first orally-active treatment for MS to market, with other players including: Novartis with its fingolimod (FTY720) in Phase III testing; Sanofi-Aventis with teriflunomide; Biogen Idec/Fumapharm with fumarate drug BG-12 in Phase II; and GlaxoSmithKline/Tanabe, whose 683699 drug is also in Phase II.

The first company to bring an oral MS drug to market is almost certain to have a billion dollar-plus product on its hands, according to Datamonitor, which has predicted that oral products will lead to a doubling of the market for MS treatments, reaching $6 billion a year in 2012.

Dr Paul Lammers, chief medical officer at Serono, said: “The formulation of oral cladribine, combined with the proposed short dosing regimen, should help patients to be more compliant with their MS therapy and lighten the patient's treatment burden associated with chronic MS."