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MS drug called effective, with checks for side effect

Genzyme Corp said yesterday 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 to avoid a potentially deadly side effect.

Results from a Phase II trial of 334 patients with multiple sclerosis showed the drug significantly reduced the risk of relapse compared to Rebif, a drug made by Merck KGaA. The data, presented at the Congress of the European Committee for Treatment and Research in Multiple Sclerosis, showed patients who had not been treated and took Genzyme's drug alemtuzumab had a 73 percent reduction in the risk of relapse.

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, Cambridge-based 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 in the trial were diagnosed with idiopathic thrombocytopenic purpura, characterized by a decline in platelet counts that can lead to potentially catastrophic internal bleeding. One patient died, four were successfully treated, and one recovered without treatment.

To protect against this possible side effect, Genzyme's monitoring program requires patients to have their blood drawn once a month.

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