The literature that I looked at states it is prescribed for RRMS patients who have failed at all of the CRAB's and have ms that is seriously progessing. The other group is SPMS. It did state it should not be prescribed to PPMS. I am not sure that I fit either of these groups other than the fact that I have proven to be allergic to all of the CRAB's and tysabri. My ms is not mild, but neither is it severe. At least that is my self assessment. I guess it is all in the eye of the beholder. On the other hand if I were to experience a significant drop in symptoms for several years, it may be worth it. He was suggesting one year -- just 4 treatments at this time.