What is alemtuzumab?

I thought I better give a little information about alemtuzumab so instead of giving you what I (probably inaccurately) think it is, here is the MS Trust info on it (and I've copied a bit below if you can't be bothered opening the fact sheet!)

1.  What is alemtuzumab? 
Alemtuzumab is an experimental drug treatment that is currently being tested in clinical trials for people with relapsing remitting MS. Although alemtuzumab is not currently licensed for use in MS, it is licensed for use in B-cell chronic lymphocytic leukaemia, a type of cancer. 

2.  How does alemtuzumab work? 
Alemtuzumab is a humanised monoclonal antibody. Antibodies are proteins produced by the immune system to fight foreign substances, such as
infections. Monoclonal antibodies can be produced in large quantities in cell culture in a laboratory and can be designed to bind to proteins on the body’s
normal cells, altering the immune response.
Alemtuzumab acts by killing T-cells which form part of the immune system.  In multiple sclerosis T-cells mistakenly attack myelin and cause the inflammation
seen on MRI scans. It is thought that the T-cells that regenerate following treatment with alemtuzumab do not include the subset which destroys myelin.

I will be getting one course of treatment (over five days) in 24 days time. I will then get my next dose a year later over three days and I may have a third dose 12 months after that.
From what I can gather, the treatment can make you feel tired, you get a rash and you can see a temporary re-emergence of MS symptoms you may have already suffered. And because the treatment destroys your T-cells, for the six to eight weeks it takes your body to regrow better behaved T-cells, your immunity is weak so you are advised to stay away from people with colds, flu and any other contagious illnesses.