LIBERTY: Erenumab shows sustained efficacy in refractory episodic migraine over 2 years
The CGRP* receptor blocker erenumab shows sustained efficacy in reducing migraine frequency over 2 years in a difficult-to-treat patient population with episodic migraine who had failed 2–4 prior preventive treatments, an interim analysis of the LIBERTY** open-label extension study shows.
The phase III LIBERTY trial comprised two phases: a double-blind phase, whereby patients were randomized 1:1 to once-monthly subcutaneous erenumab 140 mg or placebo for 12 weeks, followed by an open-label phase in which all patients who completed the double-blind phase received erenumab for 3 years. Participants were 246 patients with episodic migraine (4–14 migraine days/month) who had previously failed 2–4 preventive treatments. [AHS 2020, 1st Jul session]
Primary analysis for the double-blind phase has been reported previously, showing that erenumab was effective in this patient population compared with placebo. The current 2-year interim results represent an analysis of erenumab efficacy at week 112 of the 3-year open-label treatment phase.
“Efficacy of erenumab was sustained throughout 2 years of treatment with erenumab 140 mg in a difficult-to-treat patient population,” the researchers reported.
Changes in mean monthly migraine days (MMD) from baseline were sustained through 2 years during the open-label phase: -3.7 days at 1 year and -4.2 days at 2 years, compared with a baseline of 9.2 days in the double-blind phase.
Specifically, the proportion of patients who achieved ≥50 percent reductions in MMD with erenumab remained stable (57.2 percent) through the 2nd year of open-label treatment, similar to what was observed during the first year.
Similarly, the ≥75 percent and ≥100 percent responder rates were also sustained over 2 years, at 30.6 percent and 16.2 percent, respectively, across all treatment groups.
The improvements were seen in the overall patient population during the open-label phase, regardless of whether the patients were previously assigned to erenumab or placebo in the double-blind phase.
In addition, improvements in functional outcomes from baseline were consistent at week 112 during open-label treatment, as indicated by the Headache Impact Test (HIT-6; mean changes, -9.5) total score and Migraine Physical Function Impact Diary (MPFID; mean changes, -4.5 for physical impairment and -5.4 for everyday activities domains, respectively).
“Erenumab was well tolerated and no new safety signals were detected over the extended treatment period,” the researchers noted.
During the open-label phase, approximately 86.3 percent of the overall patient population experienced adverse events (AEs). Specifically, 82.2 percent occurred in patients continuing erenumab (ie, initially assigned to erenumab during the double-blind phase) and 90.2 percent in those initiating erenumab during open-label treatment (ie, previously on placebo).
After adjusting for exposure, the incidence rate of AEs was 198.0 per 100 patient-years in the overall population. The exposure-adjusted rate for serious AEs was 6.3 per 100 patient-years. AEs leading to discontinuation occurred in nine patients (3.8 percent). There were no deaths reported.
The most common AEs during open-label treatment were nasopharyngitis (33.9 per 100 patient-years), followed by influenza (10.3 per 100 patient-years) and back pain (6.6 per 100 patient-years).
“The 3-year open-label phase of the LIBERTY study is ongoing,” stated the researchers.