Efficacy and safety of erenumab (AMG334) in chronic migraine patients with prior preventive treatment failure: A subgroup analysis of a randomized, double-blind, placebo-controlled study

Background Erenumab was effective and well tolerated in a pivotal clinical trial of chronic migraine. Here, we evaluated efficacy and safety of monthly erenumab (70mg or 140mg) versus placebo in the subgroup of patients who had previously failed preventive treatment(s) ( 1,2 prior failed medication categories) and in patients who had never failed. Methods Subgroup analyses evaluated change from baseline in monthly migraine days; achievement of 50% and 75% reduction in monthly migraine days; and change in monthly acute migraine-specific medication days. Adverse events were evaluated for each subgroup. Results Treatment with both doses of erenumab resulted in greater reductions in monthly migraine days (primary endpoint) at Month 3 (treatment difference [95% CI], never failed subgroup: -2.2 [-4.1, -0.3] for 70mg and -0.5 [-2.4, 1.5] for 140mg; 1 prior failed medication categories subgroup: -2.5 [-3.8, -1.2], for 70mg and -3.3 [-4.6, -2.1] for 140mg;2 prior failed medication categories subgroup: -2.7 [-4.2, -1.2], for 70mg and -4.3 [-5.8, -2.8] for 140mg). Similar results were observed in the monthly acute migraine-specific medication days endpoint, and in the achievement of 50% and 75% reduction in monthly migraine days. There were no new or unexpected safety issues. Conclusion Erenumab showed consistent efficacy in chronic migraine patients who had failed prior preventive treatments and was well tolerated across subgroups.