Does Natalizumab Benefit Patients With Secondary Progressive MS?

VANCOUVER—Among patients with secondary progressive multiple sclerosis (MS), natalizumab does not delay progression of ambulatory disability, according to phase III trial results presented at the 68th Annual Meeting of the American Academy of Neurology. The drug may slow progression of upper-extremity disability, however, researchers said.

Natalizumab, a recombinant humanized monoclonal antibody against alpha-4 beta-1 integrin, reduces inflammation by inhibiting the transmigration of leukocytes into the brain. It is FDA-approved to treat relapsing-remitting MS, and data have suggested that the drug also may benefit patients with progressive forms of MS.

To investigate whether natalizumab slows disability progression unrelated to relapses in patients with secondary progressive MS, Deborah Steiner, MD, Medical Director at Biogen, and colleagues conducted ASCEND, a multicenter, double-blind, placebo-controlled, randomized trial.

Deborah Steiner, MD

The primary end point was the proportion of participants with confirmed disability progression on the EDSS, Nine-Hole Peg Test, or Timed 25-Foot Walk at six months and at the end of the trial. On the EDSS, progression was defined as an increase of at least 1.0 from a baseline EDSS score of 5.5 or less, or an increase of at least 0.5 from a baseline EDSS score of 6 or more. On the Timed 25-Foot Walk, progression was defined as an increase of 20% or more from baseline. On the Nine-Hole Peg Test, progression was defined as an increase of 20% or more on either hand.

ASCEND did not meet its primary end point. The proportion of progressors was higher in the placebo-treated group (48%) than in the natalizumab-treated group (44%), but the difference was not statistically significant.

Natalizumab treatment was, how­ever, associated with a statistically significant reduction of upper-extremity disability progression, as measured by the Nine-Hole Peg Test. Fifteen percent of participants who received natalizumab had confirmed disability progression on the Nine-Hole Peg Test, compared with 23% of participants who received placebo (odds ratio, 0.56). Dr. Steiner noted that ABILHAND, a patient-reported upper-extremity outcome, clearly differentiated Nine-Hole Peg Test progressors from nonprogressors. This finding “confirms the meaningfulness” of the treatment’s effect on upper extremity disability, the researchers said.

On the Nine-Hole Peg Test, estimated probabilities of confirmed progression over two years showed increased separation over time between the natalizumab and placebo arms. “In contrast, no significant separation over time was observed between natalizumab- and placebo-treated patients on the Timed 25-Foot Walk (38.3% vs 39.2%) or EDSS (17.4% vs 16.7%) components of the primary end point,” the researchers said.

“There’s a striking contrast between the lack of effect on ambulatory function … and the effect on upper-extremity function,” Dr. Steiner said.

Natalizumab was generally well tolerated, with adverse events consistent with its known safety profile.

The study was supported by Biogen in Cambridge, Massachusetts.

—Jake Remaly