About one in five patients on Rituxan relapsed, while twice as many on a placebo had a recurrence during a 48-week clinical trial, researchers said in this week's New England Journal of Medicine. The drug significantly reduced the number of brain lesions on MRI scans after 12 weeks, and the benefit was sustained during the rest of the study, researchers said.

Rituxan, a blood-cancer drug that's also approved for arthritis, had $2.29 billion in U.S. sales in 2007. It kills inflammatory B cells, a different type of cell than approved MS drugs. The B cells may attack the fatty myelin coating around nerve fibers linked with the disorder, or work with the T cells attacked by existing MS medicines, researchers said.

``This is wonderful news for people with MS,'' Stephen Hauser, chair of the neurology department at the University of California, San Francisco and the study's lead author, said in a telephone interview. ``It raises the possibility that B-cell targeted treatments could signal a new era of therapy.''

Genentech, based in South San Francisco, California, rose $1.27, or 1.8 percent, to $72.12 at 4 p.m. New York time today. Cambridge, Massachusetts-based Biogen, a co-promoter of the drug, fell 37 cents, or less than 1 percent, to $62.87.

Rituxan, Genentech's second-biggest product, may be an option for 400,000 patients in the U.S. with the neurodegenerative disease if the finding is confirmed in further studies. The drug's benefit is among the best seen in trials, and opens a new path of research, scientists said.

$5.5 Billion Market

The market for MS drugs exceeded $5.5 billion in 2006 and is expected to double by 2013, according to market-research firm Frost & Sullivan in New York. Rituxan costs $19,964 a year for two infusions for patients with rheumatoid arthritis, said company spokeswoman Nikki Levy in an e-mail.

Rituxan wasn't compared in the trial to existing drugs, although it was about twice as effective as products for newly diagnosed patients, such as Biogen's Avonex, Bayer AG's Betaseron, Merck KGaA's Rebif and Teva Pharmaceutical Industries Ltd.'s Copaxone, Hauser said.

Most analysts are not counting on future Rituxan sales from multiple sclerosis, until it is confirmed, said Christopher Raymond, an analyst with Robert W. Baird in Chicago.

The study, called Hermes, was from the second of three phases of clinical trials normally required for U.S. approval. It was sponsored by Genentech and Biogen. Partial results were presented last year at the American Academy of Neurology.

104 Patients

The trial enrolled 104 patients with the relapsing, remitting form of MS found in about 85 percent of newly diagnosed patients. People in the study took two intravenous infusions of Rituxan or a placebo 15 days apart.

As soon as four weeks after taking Rituxan, patients showed fewer brain lesions on MRI scans, researchers said. By 12 weeks, the drug helped people achieve a statistically significant improvement, and the effect was sustained the full 48 weeks, researchers said.

``The magnitude and rapidity of the effect is a paradigm change in how we look at MS,'' Craig Smith, neurology lead clinical scientist in the immunology department at Genentech, said in a telephone interview.

Side Effects

Side effects included fever, chills and nausea that were consistent with previous studies of Rituxan. The study wasn't designed to spot rare side effects, such as dangerous infections, and didn't follow patients long enough to see the effect of repeat dosing.

The results make Rituxan appear comparable to Biogen's Tysabri, the most effective marketed drug for MS, said John Richert, executive vice president for research at the National MS Society in New York, who wasn't involved in the study. Genzyme Corp.'s Campath has shown a similar effect in clinical trials, he said.

``The real strength is the magnitude of effect on the MRI, the relapse rate, and the duration of the response,'' Richert said of the new Rituxan finding. ``There's always the lingering concern about opportunistic infections. We'll continue to sit on pins and needles with Rituxan until we see long-term data.''

Genentech and Biogen hope to confirm the findings in a larger trial of Rituxan against primary progressive MS, a condition in which the disease worsens over time and for which there is no effective treatment. About 10 percent of MS patients have the primary progressive form, according to the National MS Society.

Tougher Issue

The larger study, called Olympus, has enrolled 439 patients taking Rituxan every six months. It was designed to answer a tougher question, whether the drug can slow the progression of disability from the disease, Smith said.

Results from that study are expected before the end of June. If the trial succeeds, Genentech may apply for U.S. approval to market Rituxan for MS patients, Smith said.

Rituxan was approved in 1997 for patients with non-Hodgkin's lymphoma, and for rheumatoid arthritis in 2006.

http://www.bloomberg.com/apps/news?pid=20601103&sid=a0G5lyXhuPJQ