* antibody that makes it difficult for immune system cells to
move into the brain and spinal cord
* for relapsing remitting MS that has not responded
to other treatment
* reduces relapse rate
* IV infusion once every four weeks
* 1/3 of patients improve in disability, suppresses 90% of MRI disease
* increases risk (1:1000) of viral infection of the brain
* infrequent side effects: headache, pain, fatigue, diarrhea, depression
* approved in 2006