Genzyme MS drug effective but monitoring required

By Toni Clarke

BOSTON, Oct 14 (Reuters) - Genzyme Corp (GENZ.O) said on Sunday that three-year data from a mid-stage trial of its experimental multiple sclerosis drug showed it to be very effective, but patients must be monitored on a monthly basis to avoid a potentially deadly side effect.

Results from a mid-stage, or Phase II, trial of 334 patients with multiple sclerosis, a central nervous system disease that can cause severe disabilities, showed it significantly reduced the risk of relapse compared to patients taking Rebif, a drug made by Merck KGaA (MRCG.DE).

The data, presented at the Congress of the European Committee for Treatment and Research in Multiple Sclerosis in Prague, showed patients who had not previously been treated and took Genzyme's drug alemtuzumab, had a 73 percent reduction in the risk of relapse compared to those taking Rebif.

Patients had at least a 70 percent reduced risk of progression of disability after three years, compared to those taking Rebif, results consistent with data presented after two years, Genzyme said.

"These results demonstrate the durability of the previously reported effect of alemtuzumab for the treatment of multiple sclerosis that, by our analysis, exceeds any marketed products and anything that we can see in development," said Dr. Richard Moscicki, chief medical officer for Genzyme.

Still, the concern among investors with the drug has been with its safety.

Six patients over the course of the trial have been diagnosed with idiopathic thrombocytopenic purpura, or ITP, a condition characterized by a decline in platelet counts that can lead to potentially catastrophic internal bleeding. One patient in the trial died from a cerebral hemorrhage. Four were successfully treated, and one was identified but recovered without treatment.

To protect against this possible side effect, Genzyme's monitoring program requires patients to have their blood drawn once a month. As long as the platelet count is monitored, any decline can be reversed with treatment, the company said.

Genzyme said it has initiated two late-stage, or Phase III, studies also testing its drug against Rebif. One trial will study patients who have received no previous treatment, and one will study those who have failed another beta-interferon therapy.

"Our hope is to file for marketing approval at the end of 2010 or in early 2011," said Mark Enyedy, president of Genzyme Oncology, the business unit that is developing alemtuzumab in multiple sclerosis.

Alemtuzumab is sold as Campath in the United States for treatment of B-cell chronic lymphocytic leukemia in patients who have failed certain other therapies. Marketed by Bayer (BAYG.DE), Campath is sold in Europe under the name MabCampath.

Genzyme and Bayer are co-developing the drug in oncology, multiple sclerosis and other indications. Bayer has worldwide marketing rights.

Campath, if approved, would compete in an increasingly competitive market, dominated by Rebif and Biogen Idec Inc.'s (BIIB.O) Avonex. Physicians are also growing increasingly comfortable with Biogen's multiple sclerosis drug Tysabri, which it partners with Elan Corp (ELN.I) of Ireland.

Tysabri was taken off the market in 2005 after being linked with three cases of progressive multifocal leukoencephalopathy, or PML. It was allowed back last July under a strict risk monitoring program and since then there have been no new reported cases of the brain infection.