If the drug is helping his wife, why would he take her off it? These days of personalized medicine, it very well may be helping and there could be a genetic component to why. A lot of people are still on actimmune, for whatever reason there's a small group of outliers where it appears to work very well.
For the bio ms phase 2 if rrms, 15 months should have been long enough, it's certainly not a competitive drug in rrms if it takes that long.
For the phase 3 in spms, i'm not sure how long the p3 is, but I would say more like 2-3 years. That's assuming it has an effect.