We have noted the great potential of the Multiple Sclerosis Drug Alemtuzumab in a previous posts 
Note that current research see it prescribed for the Relapsing Remitting (RRMS) form, which is indeed what the clinical trials mentioned in  were about, even though their title was much more general.
Rate of success is impressive, quoting :
“…The study showed that after 2 years, almost a quarter of patients had achieved a disease activity–free state compared with none of those treated with interferon…”
Also the drug’s injection is grouped in 5 consecutive days, the first year and 3 consecutive days the second year, which much better than the year-long administration of many interferons.
The risks are substantial, though:
“…that side effects of the drug have encompassed potentially serious autoimmune diseases, including thyroid disorders and immune thrombocytopenia, both of which require careful monitoring and management…”
This is why the drug is considered only for difficult MS cases
Alemtuzumab binds to the surface of a protein (CD-52) present on the surface of certain lymphocytes, marking them for destruction.
Large granular lymphocytes include natural killer cells (NK cells). Small lymphocytes consist of T cells and B cells. (Wikipedia)
This remarkable MS success story has a murky marketing aspect: The drug existed as a Leukemia medication under the name of Campath , but was put on a restricted market path through patient access programs”
- medinewsdigest ; “IN BRIEF: STATUS March 2012: Emerging Disease-Modifying Therapies (DMT) in Multiple Sclerosis.” ; March 2012
- MedScape ; “Alemtuzumab Benefits Hard-to-Treat MS Patients” ; June 2013
- FiercePharma ; “Genzyme mulls Campath giveaway for cancer patients” ; No 2010
- FiercePharma ; “Sanofi pulls Campath to clear way for higher-priced Lemtrada” ; Aug 2012