Tysabri Trial Shows Impact on Disability Progression, Relapse Rate in MS

Biogen Idec and Elan have announced that the Phase III Tysabri AFFIRM monotherapy trial achieved the two-year primary endpoint of slowing the progression of disability in patients with relapsing forms of multiple sclerosis (MS).

Tysabri (natalizumab) treatment led to a 42 percent reduction in the risk of disability progression relative to placebo. These data also demonstrated a 67 percent reduction in the rate of clinical relapses over two years, which was sustained and consistent with the previously reported one-year results.

Other data from AFFIRM at two years, including magnetic resonance imaging measures and immunogenicity were similar to previously reported results. The adverse event profile at two years was also consistent with previously reported results. Common events included headache, fatigue, urinary tract infection, depression, lower respiratory tract infection, limb and joint pain, and pharyngitis.

The incidence of infections in Tysabri-treated and placebo-treated patients was similar. Serious infections occurred in 3.2 percent and 2.6 percent of patients, respectively. These included bacterial infections, such as pneumonia and urinary tract infections, which responded appropriately to antibiotics. Tysabri has also been associated with hypersensitivity reactions, including serious systemic reactions that occurred at an incidence of less than 1 percent of patients.