Long-Term Safety and Tolerability of Fremanezumab for Migraine Preventive Treatment in Japanese Outpatients: A Multicenter, Randomized, Open-Label Study

Introduction Early discontinuation and poor adherence are common limitations of conventional preventive migraine medications that limit their long-term efficacy. Therefore, a migraine preventive medication with favorable long-term safety is warranted. Objective This study aimed to evaluate the long-term safety and tolerability of fremanezumab for the preventive treatment of chronic or episodic migraine in Japanese patients. Methods In this 52-week, randomized, open-label, parallel-group study, fremanezumab monthly or quarterly was administered in newly enrolled Japanese patients with chronic migraine or episodic migraine. Safety was assessed by monitoring of treatment-emergent adverse events, including injection-site reactions, laboratory and vital sign assessments. Newly enrolled patients and rollover patients from previous phase IIb/III trials who did not receive fremanezumab in this study were included in the immunogenicity testing cohort (n = 587). Efficacy outcomes included changes from baseline in the average monthly migraine days and headache days of at least moderate severity. Other efficacy outcomes included changes in disability scores. Results A total of 50 patients were enrolled with chronic migraine (monthly, n = 17; quarterly, n = 17) or episodic migraine (monthly, n = 8; quarterly, n = 8). The most commonly reported treatment-emergent adverse events were nasopharyngitis (64.0%) and injection-site reactions (erythema, 24.0%; induration, 10.0%; pain, 8.0%; pruritus, 6.0%). The discontinuation rate was low (4.0% from adverse events, 2.0% from a lack of efficacy) and no deaths were reported. The incidence of anti-drug antibody development was low (2.4%). Fremanezumab reduced monthly migraine days and headache days of at least moderate severity from 1 month after initial administration, and this effect was maintained with no worsening throughout 12 months. Fremanezumab also led to sustained reductions in any acute headache medication use and headache-related disability at 12 months. Conclusions Fremanezumab administered monthly and quarterly was well tolerated in patients with chronic migraine and episodic migraine and led to sustained improvements in monthly migraine days and headache days of at least moderate severity throughout 12 months. Clinical Trial Registration ClinicalTrials.gov Identifier: NCT03303105.