>>Is there a big difference in the underlying biology? To my knowledge, the answer is probably not. Rather, the main difference is one of terminology—SPMS patients are sicker (they don’t relapse) and hence more difficult to treat.
If there is no difference, then why do some with RRMS progress to SPMS and others do not? Why do some progress quickly and others slowly? Is it just severity? Is something causing the immune attack to shift [fail to shift] targets to [away from] the nerve?
It seems to me that whatever factor[s] accounts for the difference in result MAY allow for an alternate therapeutic.
Unfortunately, I know next to nothing about science.
ij