US firm Biogen Idec and its Irish partner Elan have enrolled the first patient in a new Phase IIIb clinical trial to test Tysabri as a treatment for relapsing remitting multiple sclerosis (RRMS).

The randomised, rater-blinded, active-controlled trial, called SURPASS, will directly compare the drug’s effect with Copaxone or Rebif.

The trial, expected to enrol 1,800 patients in 27 countries, will also check the effectiveness of the drug’s early use in the treatment algorithm.

RRMS is a chronic inflammatory disease that affects the central nervous system and, if progressed, can cause permanent damage.