Recovery from attacks is greater the earlier you are in the disease course; this may explain why subjects recovered more from disability in the phase 2 or earlier study compared to what has been reported in the press release yesterday.
The population of MS'ers from which these studies recruited are also different; the populations for more recent or later studies tend to have less active disease. This makes it more difficult to see differences between the treatment arms.
Finally, the
phase 2 study tested two doses of Alemtuzumab (low and a high dose), where as the
phase 3 study only tested the low dose. This is important as the high dose was more effective than the low dose; this will explain why the results in the
phase 3 study in relation to relapse reduction is not as good as that seen in the
phase 2 study.