Current Series: Multiple Sclerosis: A Disease of an Immune System Gone Awry

Patricia K. Coyle, MD: Pediatric multiple sclerosis refers to the development of MS at age 18 or earlier. That’s a little bit young. It accounts for about 3% to 5% of MS. However, other than the age of onset, I believe there are no fundamental differences, no major differences, between a pediatric onset and an early adult or midlife onset. What we do know is that the younger you are, the higher the attack rate and relapse rate. Pediatric-onset MS is going to have a higher attack rate because of their younger age. They’re also going to be enriched for relapsing MS. It would be very unusual to see primary-progressive MS in a pediatric-onset setting.

In addition, you have a developing brain. The assault on the central nervous system [CNS] in a young person can have somewhat more devastating consequences in the short term, and even in the long-term, with regard to cognition. But I don’t think that, fundamentally, we’ve seen any differences between pediatric-onset MS and later-onset MS. I think that’s very important when we come to talking about the therapy of pediatric MS.

The PARADIGMS trial is a landmark trial because it’s the first completed phase III trial in pediatric MS. This study was a 2-year study to be followed by a 5-year open label. They took patients with pediatric MS onset from the ages of 10 to 18. They had 215 children and adolescents with relapsing MS who were randomized to an oral disease-modifying therapy [DMT] called fingolimod—either the adult dose of 0.5 mg or if the child was smaller, a half-dose of 0.25 mg—or intramuscular interferon beta-1a at 30 mcg injected weekly.

What this study showed was that fingolimod was superior to the interferon beta. The primary outcome was annualized relapsed rate, and that was 0.12 versus 0.67. That was an 82% decrease in relapses with the oral agent over the injectable agent. In addition, there was benefit on confirmed disability, which was significantly less in the oral arm. There was better suppression of new MRI [magnetic resonance imaging] lesion activity. There was improvement regarding new t2 lesions and contrast lesions, and a better impact on atrophy. So, it was a landmark trial because it was the first successful phase III trial, but it also showed that the oral treatment was much superior to the intramuscular weekly interferon beta, which had been a favorite therapy for pediatric MS. I think it really changed the landscape and emphasizes, quite frankly, that when you’re evaluating a pediatric MS patient who has no substantive differences from an adult-onset MS patient, you should be using the best disease-modifying therapy for them. I don’t care if you don’t have a phase III trial. You should be using the best therapy to minimize damage to their CNS.