Genentech and Biogen Idec’s Phase II/III study of Rituxan (rituximab) on patients suffering from primary-progressive multiple sclerosis failed to meet its primary endpoint, which was the time to confirmed disease progression during the 96-week treatment period. The randomized, double-blind, placebo-controlled, multi-center study evaluated the efficacy, safety and tolerability of four courses of Rituxan in 439 patients. Most events in the Rituxan arm were mild to moderate and the overall adverse event rates for the drug were 16.4%, as compared to 13.6% for placebo.