Tests of a new long-acting version of one of the oldest multiple sclerosis (MS) drugs on the market show it worked significantly better than placebo in reducing the number of patient relapses and developments of new or active lesions, researchers report. Most important, they add, the updated version was effective even though injections were given every two weeks instead of every other day, and it appears that fewer patients develop resistance to it.

The industry-funded, international clinical trial led by a Johns Hopkins scientist found that pegylated interferon beta worked far better than placebo for people with the most common form of MS. The beneficial effects seen in this study were comparable to what was found in previous studies in which the standard formulation of interferon beta (which must be taken more frequently) was compared to placebo.

In a report on the trial, published May 1 in The Lancet Neurology, the researchers say they also found that while roughly 20 percent of MSpatients typically develop antibodies against the drug that ultimately neutralize its effects, fewer than 1 percent in the new study did, suggesting far more patients could benefit from the new formulation.

"While this isn't a brand new blockbuster drug, I do think it will improve compliance and tolerability and therefore positively impact the quality of life of people with MS who take interferon beta," says study leader Peter A. Calabresi, M.D., a professor of neurology at the Johns Hopkins University School of Medicine.

"The data are very, very clear," Calabresi adds. "We can make things easier for our patients without dangerous side effects just by tweaking what we know to be a safe, 20-year-old drug."