BRIAN APATOFF, MD, PhD: Because multiple sclerosis is a chronic condition where patients need to treated over decades, it's important to generate clinical trial data of some duration. So brief studies, 12, 24 months aren't going to convey as much meaningful therapeutic data as longer term trial data. So recognizing that patients are in it for the long haul, we need to feel confident that any sort of clinical trial results are going to apply for long-term therapy, long-term benefits of treatment.

There are patients that have been on glatiramer acetate now in an open-label trial for six, now up to eight years. It does show that there appears to be sustained benefits of therapy for those patients remaining on drug. Now this group of patients is a very small subset of the patients that originally entered into the double-blinded placebo-controlled study.

The concern with any open-label data is that you are selecting for a group of patients that are either going to do well, just by nature of their relatively benign course, or people that are super responders to that particular therapy. So while I think it's helpful to have this long-term data to address issues of safety and it's good to know that there is no long-term toxicity of treatment, I think you have to be very guarded as far as making any strong conclusions about efficacy.

FREDERICK MUNSCHAUER, MD: We have a number of studies now that are extensions of original phase III clinical trials. They are open-label trials. They are no longer placebo-controlled groups. When we have these extension studies, they can give us substantial information about the long-term safety of using immunomodulatory drugs in multiple sclerosis, as well as hints, at least, about whether or not the effectiveness of these drugs is preserved over time.

The take-home message from these four year studies, these observational extension studies, some cases lasting now up to eight years, is that the immunomodulatory agents used in treating multiple sclerosis are safe. That's important for the average neurologist.

In the United States now, approximately 45% of all people with relapsing multiple sclerosis are not on any therapies. Neurologists make the decision to treat based on the balance between effectiveness and safety. These extension studies now are firmly establishing that interferons and Copaxone are safe in the long-term. I think that should translate into clinical practice, where we treat people with the relapsing forms of multiple sclerosis with these agents, knowing that they are effective, and knowing that at least in the long-term they appear to be safe. It's the way to go in treating relapsing MS now.