Background: Erenumab is a monoclonal antibody (mAb) against the calcitonin gene related peptide (CGRP) receptor and is commonly used in migraine prophylaxis. Pivotal and open-label studies show a good safety and tolerability. However, little is known about possible predictors, dose dependence and time course of development of adverse events (AEs) during the treatment under real-world conditions.

Methods: Clinical routine data of 128 patients with migraine treated in the West German Headache Center Essen were analyzed regarding AEs during a treatment interval of up to 12 months (3mo n = 128, 6mo n = 105, 9mo n = 74, 12mo n = 54). Patients obtained subcutaneous erenumab injections with either 70 mg or 140 mg per month. The occurrence and alterations of AEs were evaluated. All reported AEs, regardless of their severity, were included. AEs were graded using the common terminology criteria for adverse events (CTCAE). Possible parameters that could influence the occurrence of AEs (sex, episodic or chronic migraine, medication overuse headache, aura and the dosage of erenumab) were analyzed using the Chi-squared test, alpha adjustment was done using the Bonferroni’s correction (6 tests, adjusted alpha = 0.0083).

Results: The proportion of patients who reported at least one AE were stable over the course of 12 months (after 3mo = 37%, 6mo = 36%, 9mo = 32%, 12mo = 35%). All reported AEs were grade 1 according to CTCAE with one exception (grade 2). Throughout the interval, five AEs were mostly reported: constipation, skin reactions, fatigue, sleep disturbances and nausea/emesis. Discontinuation of erenumab therapy was rarely caused by AEs (5/49). Increasing the dosage from 70 mg to 140 mg per month caused no higher frequency of AEs (Chi-squared test, p = 0.57). Significant more AEs were reported by females and by patients with aura (Chi-squared test, p < 0.001, respectively).

Conclusion: In general, erenumab is well tolerated up to a treatment interval of 12 months and reported AEs rarely lead to discontinuation of therapy. A higher dosage does not increase the patient reported AEs. Furthermore, no habituation of AEs is observed. Nevertheless, females and patients with aura seem to be more prone to have AEs.