Interferon Works Best in Early Stages of MS
Patients in the European study experienced a significant delay in the progression of their disease, says McFarland. In the North American study, interferon did not slow the progress of the disease, although it did diminish almost every secondary feature studied.
"From that standpoint, the [North American] trial might be considered a failure," says Goodkin. But these findings, he points out, led the investigators to wonder: "Were the North American patients too far advanced to respond to treatment?"
The European patients were younger and at an earlier stage in their disease, says McFarland. Their relapse rates were twice as high as those of their North American counterparts, and they were most likely still in the inflammatory phase of their MS. According to McFarland, this suggests that, to delay disease progression, interferon must be given during the earlier, R/R phase of MS, when inflammation is still active.
However, says Goodkin, "The treatment effect on the secondary outcomes should not be dismissed. I think we can learn a tremendous amount about who the most appropriate patients are for this therapy. I think all of our current treatments work best in the early stages of the disease because they work on the inflammation. If we treat the patient after the inflammatory component of the disease is [no longer] active, interferon will not work."
Unfortunately, other than the suggestion that interferon is best used on patients whose MS it still relatively new, McFarland says his research team has not been able to find a single feature that identifies which patients are most likely to respond. He believes this reflects the complex nature of MS.
"Interferon definitely has an impact on this disease," says Mark S. Freedman, MD, who participated in yet another trial looking at the effects of interferon on patients in the early stages of MS. That study compared two different doses of interferon in 560 patients at 22 centers around the world and showed that the higher doses could slow the progression of MS. However, he says, these studies, which lasted 2-4 years, "are short-term studies in the life of a very chronic disease. Early treatment with the right dose is important. But it's not enough to have a drug that has an effect -- you have to be able to max out that effect."