Two-year effectiveness of erenumab in resistant chronic migraine: a prospective real-world analysis

Background Controlled and real-world evidence have demonstrated the efficacy of calcitonin gene related peptide (CGRP) monoclonal antibodies (MABs) in migraine. However, data on the over-one-year sustained effectiveness of CGRP MABs in resistant chronic migraine (CM) is sparse. Methods This is a two-year real-world prospective analysis of an ongoing single centre audit conducted in patients with resistant CM. Patients received monthly erenumab for six months before assessing its effectiveness. Responders were considered those who achieved at least 30% reduction in monthly migraine days (MMD) by month 6, compared to baseline. Secondary outcomes were also analysed, including changes of the Headache Impact Test version 6 (HIT-6). Results One hundred sixty-four patients [135 (82.3%) females; mean age 46 SD 14) years] were included in the audit and 160 patients analysed. Patients had failed a mean of 8.4 preventive treatments at baseline. At month 6, 76 patients (48%) were 30% responders to erenumab, 50 patients (31%) were 50% responders and 25 (15%) were 75% responders. The mean reduction in MMD at month 6 was 7.5 days compared to baseline (P < 0.001). At month 12 and month 18, 61 patients (38%) and 52 patients (33%) remained 30% responders respectively. At month 24, 36 patients (23%) remained 30% responders, 25 patients (16%) and 13 patients (8%) were respectively 50% and 75% responders. Compared to 95% of patients at baseline, at months 6, 12 and 24, 46%, 29% and 16% of responders respectively had severe disability. At least one adverse event at month 6, 12, 18 and 24 was reported by 49%, 19%, 11% and 3% of patients. By month 6, 13% of patients discontinued the treatment because of side effects, often constipation. Conclusions Long-term sustained effectiveness of erenumab was reported only by a minority of resistant CM patients. Although more research in resistant migraine is needed, Erenumab can provide long-term meaningful reduction in migraine load and migraine-related disability in some patients.