SAN FRANCISCO – Now that erenumab has won approval as the first-in-class calcitonin gene-related peptide inhibitor for prevention of episodic and chronic migraine, a flurry of new studies shedding light on how the drug might best be used in clinical practice emerged as a highlight of the annual meeting of the American Headache Society.
Erenumab (Aimovig) is a fully human monoclonal antibody targeting the calcitonin gene-related peptide (CGRP) receptor. It was approved by the Food and Drug Administration at 140 and 70 mg monthly by subcutaneous injection on the strength of the required 12-week, double-blind, placebo-controlled clinical trial data. Among the fresh data presented at the headache meeting was reassuring evidence of the monoclonal antibody’s continued high degree of safety and tolerability for episodic migraine after more than 3 years of therapy, as well as a suggestion that the biologic’s efficacy for chronic migraine was not only sustained but actually increased over the course of a 1-year study.
Also, erenumab appears to be a novel treatment option for patients who have previously failed adequate trials of two to four standard preventive therapies. In addition, it has now demonstrated efficacy in reducing overuse of acute migraine drugs such as triptans, ergots, and opioids.
Here are the highlights:
One-year safety and efficacy for chronic migraine
Stewart J. Tepper, MD, presented results of a 1-year, open-label extension study that began after participants completed a pivotal 12-week, placebo-controlled, double-blind, randomized trial whose findings have been published (Lancet Neurol. 2017 Jun;16[6]:425-34). At the end of the 12-week, double-blind period, the mean number of monthly migraine days (MMD) in the erenumab group had dropped by 6.6 days from 18.1 at baseline. Subsequently, after 52 weeks of open-label erenumab at 140 mg monthly, that figure had further improved to 10.5 fewer MMDs than at baseline.
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Dr. Stewart J. Tepper
“That’s encouraging for our patients in that we will be able to tell them that if you’re a responder, you’re likely to show some continued improvement over time,” observed Dr. Tepper, professor of neurology and director of the headache clinic at Dartmouth University in Hanover, N.H.
During 527 patient-years of open-label therapy, at least a 50% reduction in MMDs was achieved by 67% of patients in the 140-mg group and 53% in the 70-mg group.
“I think it’s also important to look at the rate of 75% or greater reduction in MMDs, which is the responder rate most closely linked to a drop in disability. That rate at 52 weeks was 42% at 140 mg and 27% at 70 mg,” the neurologist continued.
At week 52, 12.7% of patients on erenumab at 140 mg monthly had no migraines at all during the previous month.
The mean number of acute migraine-specific medication days per month decreased by about 4 days in the erenumab group during the 12-week, double-blind trial and continued to fall during the open-label extension study, with a mean reduction from baseline of 6.7 days at week 52.
“That’s clearly sustained efficacy, and it looks like some accumulating efficacy,” Dr. Tepper said.
Safety and tolerability continued to be excellent, as in the parent 12-week study.
“One of the very interesting findings we saw which differentiates erenumab from, say, onabotulinumtoxinA, is that if you looked at the patients who were on placebo during the 12 weeks of the double-blind study and then looked at the first month they went on erenumab, they caught up immediately to the patients who’d been receiving the monoclonal antibody from the beginning. That’s unlike onabotulinumtoxinA in the regulatory trials, where the patients who initially received placebo never quite caught up to those who received active therapy from the beginning,” he said.
Dr. Tepper emphasized that a clear-eyed view of an open-label study needs to recognize that only responders would have stayed in the erenumab study for a full 52 weeks, so the results paint an overly rosy picture of overall efficacy. Even so, he found the results impressive. Of 609 patients who enrolled in the study, 74% completed it.
“It’s a very encouraging 1-year study for erenumab,” he concluded.