Sequential use of OnabotulinumtoxinA and Erenumab in Chronic Migraine: Retrospective Real-World Report on Bidirectional Switching

In clinical practice, switching between preventive treatments is common in patients with chronic migraine when efficacy is insufficient or tolerability is poor. With the advent of more targeted therapies, such as onabotulinumtoxinA and calcitonin gene-related peptide (CGRP) monoclonal antibodies, treatment options have expanded, yet evidence to guide sequencing decisions remains limited. The aim of this study was to investigate the real-world effectiveness of switching between onabotulinumtoxinA and erenumab and vice versa in patients with chronic migraine who showed inadequate response to their initial preventive treatment. This retrospective real-world study included patients with chronic migraine treated at the Headache Center, Charité-Universitätsmedizin Berlin between October 2022 and December 2024. Eligible patients had received both onabotulinumtoxinA and erenumab in sequence, switching as a result of insufficient efficacy or tolerability. A very good response was defined as a ≥ 50% reduction in monthly headache days in the third month after the switch. Out of 632 screened patients, 78 met the inclusion criteria (84.6% female; mean age 43 ± 14 years). Of these, 54 switched from onabotulinumtoxinA to erenumab, and 24 from erenumab to onabotulinumtoxinA. A very good response was observed in 14 patients (17.9%): 10/54 (18.5%) after switching to erenumab and 4/24 (16.7%) after switching to onabotulinumtoxinA. Sequential preventive treatment with onabotulinumtoxinA and erenumab resulted in a very good response in about one-fifth of patients. Although both treatments target the CGRP pathway, their distinct mechanisms of action may still provide benefit when switching therapies after initial failure.