Long-term efficacy and safety of erenumab in Japanese patients with episodic and chronic migraine: results from a 28-week open-label treatment period of a randomised trial.

Objectives: To evaluate the 1-year efficacy and safety of once-monthly erenumab 70 mg following a 24-week double-blind treatment period (DBTP) of a phase III randomised study of Japanese patients with episodic migraine (EM) or chronic migraine (CM).

Design: Multicentre open-label study.

Setting: A total of 41 centres in Japan.

Participants: Patients completing the DBTP continued into the 28-week open-label treatment period (OLTP). 254 of 261 (97.3%) randomised patients continued into the OLTP; 244 (93.5%) completed treatment.

Interventions: Once-monthly subcutaneous erenumab 70 mg.

Main Outcome Measures: Changes from baseline in monthly migraine days (MMD) and monthly acute migraine-specific medication treatment days (MSMD) reported via patient eDiary; proportion of ≥50% and ≥75% responders in MMD reduction from baseline; incidence and exposure-adjusted incidence of treatment-emergent adverse events (TEAEs).

Results: At week 24 of the DBTP, the mean (SE) change from baseline in MMD for the erenumab group was -3.8 (0.4) days (EM, -3.0 (0.4); CM, -5.2 (0.8)); in MSMD, -2.6 (0.4) days (EM, -2.1 (0.4); CM, -3.4 (0.7)). At the end of the OLTP (52 weeks postbaseline), the mean (SE) change from baseline in MMD was -4.7 (0.3) days (EM, -3.4 (0.3); CM, -6.9 (0.6)); in MSMD, -3.3 (0.3) days (EM, -2.4 (0.3); CM, -4.6 (0.5)). The proportion of ≥50% responders for MMD reduction in the erenumab group was 34.1% at week 24; 44.4% at week 52. The exposure-adjusted incidence of TEAEs was 219.7 per 100 patient-years during the OLTP (DBTP, 251.0 for the erenumab group). The most common TEAEs during the OLTP were nasopharyngitis, constipation and influenza. No new safety concerns were identified.

Conclusions: Erenumab treatment was associated with reduced migraine frequency in Japanese patients with EM or CM for up to 1 year. Overall safety results from the OLTP were consistent with DBTP results.

Trial Registration Number: NCT03812224.