Real-World Patient Experience With Erenumab for the Preventive Treatment of Migraine

Background: Erenumab, a calcitonin gene-related peptide (CGRP) receptor monoclonal antibody, has been well tolerated with good efficacy for the preventive treatment of episodic and chronic migraine in phase 2 and phase 3 clinical trials. Limited post-market observations are available to validate these findings in a real-world tertiary headache clinic population with complex comorbidities and refractory migraine. Objective: The goal of this study is to demonstrate the real-world performance of erenumab among patients in a tertiary care headache clinic by describing patient selection, experience, and clinical characteristics after 6 months of erenumab therapy. Methods: A retrospective, exploratory, observational study was conducted on patients receiving at least 1 erenumab injection (70 or 140 mg). Baseline data obtained by chart review and telephone calls were compared to 6-month follow-up telephone calls. The primary outcome was the reduction in self-reported headache days per month at baseline compared to 6 months for those with complete 6-month data. The significance level was set at P <.05. Secondary analyses explored the distribution of headache severity, responder rates, Migraine Disability Assessment scores, adverse effects, ineffective preventives, comorbidities, wearing-off, and discontinuation. Results: Of the 101 patients who consented to participate, 89.1% (90/101) were women, and the mean age of all patients was 49 years (range, 19-80 years). At baseline, 94.1% (95/101) of patients had chronic migraine, 5.0% (5/101) had episodic migraine, and 18.8% (19/101) had medication overuse headache. The mean (SD) number of baseline headache and migraine days per month for the entire cohort were 24.3 (8.2) and 18.2 (9.3) days, respectively. Participants had numerous comorbidities and had tried a mean of 11.2 unique oral medications and 4.8 unique medication categories before receiving erenumab, including 83.2% (84/101) who had also received onabotulinumtoxinA. Six-month post-erenumab follow-up data were available for 42.6% (43/101) of participants. For these 43 participants, the number of headache days per month decreased significantly by 6.5 days from a baseline mean (SD) of 24.8 (6.47) days to 18.3 (12) days at 6-month follow-up (P <.001); similarly, the monthly migraine days decreased significantly by 8.4 days from a baseline mean of 19.1 (9.3) days to 10.7 days at 6-month follow-up (P <.001). The 50% responder rate was 34.9% (15/43) for monthly headache days and 54.8% (23/43) for monthly migraine days. Of all 101 participants, 28 (27.7%) discontinued erenumab, primarily because it was ineffective (39.3%, 11/28) or because of adverse effects (42.9%, 12/28). Conclusion: This post-market observational study of patient experience describes response to erenumab in a real-world tertiary headache clinic with a complex patient population. Overall, these complex patients had a significant positive clinical response to erenumab, but with high rates of discontinuation. This study also noted a 1-week wearing-off response and high rates of constipation. Further post-market studies are needed to better characterize patient selection and real-world response to erenumab.