Oral Tysabri-like drug in development
A large study has found that a new drug in development for relapsing-remitting multiple sclerosis (MS) appears to reduce inflammatory activity in the brain (Miller and colleagues. Lancet Neurol 2012; epublished January 5, 2012). The drug, firategrast, acts in a way that is similar to how natalizumab (Tysabri) works, but is given orally.
The phase II study gave one of four different doses of firategrast or a placebo to 343 people with MS over a period of 24 weeks. Only the two highest doses had a significant effect on the number of new inflammatory lesions in the brain, as seen on magnetic resonance imaging (MRI). The reduction in new enhancing lesions was 49% with the higher dosing. The most notable side effect was a higher rate of urinary tract infections in people taking firategrast.
Like natalizumab, firategrast targets a molecule called alpha4-integrin, blocking activated immune cells from crossing into the central nervous system (the brain and spinal cord). While natalizumab is administered by infusion once a month, firategrast is taken as a pill twice a day.
Because of the similarities of firategrast and natalizumab, investigators were concerned about the emergence of PML (progressive multifocal leukoencephalopathy). PML, a potentially fatal brain disorder, is caused by reactivation of the JC virus. Fortunately there were no cases of PML or evidence of JC virus activation during this study.
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