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Ampyra (Dalfampridine) Fails Main Goal of Post-Marketing Study in Patients With Multiple Sclerosis
Acorda Therapeutics Inc. announced on August 13 that a post-marketing study of its multiple sclerosis (MS) drug Ampyra (dalfampridine) failed to meet the main trial goal of an improvement in patients' walking speed.
The study randomly assigned 430 patients to receive 5 mg of dalfampridine-ER twice daily, the currently marketed dose of 10 mg of dalfampridine-ER twice daily, or placebo. Treatments were administered for 4 weeks. Participants returned after 2 weeks on study drug for interim measurements (Visit 2), and again at 4 weeks (Visit 3).
The primary outcome was the change in walking speed (feet/second) on the Timed 25-Foot Walk (T25FW) test at Visit 3, measured at the time of peak plasma drug concentration, versus baseline.
Improvements in the primary outcome for the 5-mg dose (0.423 ft/sec; P = 0.457) and the 10-mg dose (0.478 ft/sec; P = 0.107) at Visit 3 were not statistically significant compared with placebo (0.363 ft/sec).
In a post hoc analysis of the T25FW data, all measures were combined prior to treatment as the baseline, and all measures were combined during treatment as the on-drug value. Using this method, the average change from baseline in walking speed was significantly greater for the 10-mg group compared with placebo (0.443 vs. 0.303 ft/sec, respectively; P = 0.014) but not for the 5-mg group (0.366 vs. 0.303 ft/sec, respectively; P = 0.292).
In addition, using a responder definition of average improvement in walking speed of at least 20% from baseline, the 10-mg group had significantly more responders than the placebo group (44% vs. 27%, respectively; P = 0.004). The 5-mg group did not show a significant increase in response compared with placebo (32% vs. 27%, respectively; P = 0.366).
Ampyra is approved by the FDA as a treatment to improve walking ability in patients with MS.
For more information, visit the Acorda Therapeutics Web site.