BOSTON (Reuters) - Genzyme Corp 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 .
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.
