Genentech ( DNA) and Biogen Idec ( BIIB) on Friday announced positive results from a late-stage study on Rituxan in patients with rheumatoid arthritis (RA). Rituxan is already approved as a second-line therapy when drugs called TNF inhibitors, which include Enbrel, Humira and Remicade, have already been tried. The so-called Serene study involved patients not yet treated with a TNF inhibitor who were given two infusions of Rituxan (at a 500-mg or 1,000-mg dose) in combination with Methotrexate. The companies' hope is that this study will help support approval for the drug as a first-line treatment for RA, tapping the wider, non-TNF treated population. "This much larger market opportunity could lead to nearly $300
million in upside to our 2010 estimates (or +$0.03 and +$0.10 in EPS for Genentech and Biogen), with likely more upside to consensus estimates," wrote JP Morgan analyst Geoffrey Meacham in a note to investors Friday. About the study: The effectiveness of RA drugs is measured through ACR (American College of Rheumatology) scores. Each score indicates that patients had the corresponding percentage of improvement in an identified set of symptoms -- ACR20 means that patients had a 20% improvement. In the Serene study, Rituxan met its primary endpoint of improvement in ACR20 scores at 24 weeks. The company said the incidence of adverse events was similar between the two arms of the study. "While use of Rituxan with MTX is well-established in RA patients who have had an inadequate response to anti-TNF therapy, this is the first phase III study demonstrating that Rituxan improved symptoms of RA in patients who had not previously been treated with a biologic therapy," said Hal Barron, Genentech's chief medical officer. "These findings support the potential use of Rituxan earlier in the course of treatment for this debilitating disease." More data on Rituxan could emerge in the first half of 2008 from the Olympus study in PPMS and the Explorer study in lupus. "Today's trial announcement for Rituxan is the first of three expected in 1H08 that could lead to over $1 billion in upside to our Rituxan sales estimates by 2010," wrote JP Morgan's Meacham. Genentech recently was trading up 14 cents, or 0.2%, at $68.56, while Biogen was up 88 cents, or 1.5%, at $59.01.