Post hoc analysis of clinical trial data and pharmacokinetic data to assess wearing-off of erenumab within monthly treatment cycle.

BACKGROUND: Treatment wearing-off has been reported for calcitonin gene-related peptide-pathway monoclonal antibodies, including erenumab, specifically in the last week of the monthly dosing cycle. OBJECTIVE: We sought to determine the consistency of erenumab effect throughout the monthly treatment cycle. METHODS: In this post hoc analysis of four pivotal double-blind, randomized controlled studies of erenumab in episodic and chronic migraine, we assessed wearing-off based on change in weekly migraine days at week 4 versus average over weeks 1-3 in each monthly dosing cycle. Analyses were conducted at each monthly dosing cycle in all patients, in responders (≥50% reduction in weekly migraine days), and in consistent responders (response in ≥2monthly cycles). RESULTS: There was no evidence of wearing-off in the full study populations of two global studies (N = 946 and N = 656) and two Japan studies (N = 475 and N = 261). In the full study population, mean change in weekly migraine days at week 4 compared with the average over week 1-3 ranged from 0.15 days improvement to 0.19 days worsening in the placebo group and 0.08 days improvement to 0.20 days worsening in the erenumab groups. A subgroup of responders experienced wearing-off, but the extent of wearing-off did not differ between erenumab and placebo groups. The mean change in weekly migraine days at week 4 compared with the average over weeks 1-3 ranged from 0.34 to 0.61 days worsening in the placebo group and 0.27 to 0.78 days worsening in the erenumab groups. Few patients had persistent wearing-off in ≥2 consecutive monthly treatment cycles. For erenumab-treated responders, serum erenumab concentrations were similar among patients experiencing wearing-off and those maintaining response. CONCLUSION: No systematic wearing-off with erenumab was identified. Further research is needed to determine if wearing-off reported for some patients in clinical practice reflects a true treatment response pattern or normal fluctuations in migraine frequency.