Abstract text (incl. figure legends and references)

Question: Is it worth switching monoclonal antibodies for migraine prevention when there are side effects or efficacy failure?

Methods: Prospective study of patients that changed monoclonal antibody for migraine prevention due to lack of efficacy or side effects, in a one-year period, from a single headache centre. Data regarding demographic and clinical features, comorbid diseases, and monoclonal therapy (first and second monoclonal used, length of therapy, reason for change, profile of side effects and clinical response) were prospectively collected. Response to therapy was evaluated through headache diaries, patient interview and clinical validated scales.

Results: From a total of 82 patients treated at our centre, 16 changed monoclonal therapy (15 women, one male, median age of 45 years, median duration of migraine 23.3 years), 12 of them due to ineffectiveness (initial or latter loss of efficacy after initial response) in 4 of these also because of adverse events) and in 4 exclusively to adverse events. All except two patients changed from erenumab to anti-ligand antibodies (fremanezumab or galcanezumab). First monoclonal therapy lasted from 4 to 24 months (median 12 months) and the second one 1 to 8 months (median 4,6). All the patients that suffered adverse events (high blood pressure, constipation, and local reactions) with the first treatment didn´t experience them with the second one. In the case of lack of efficiency of the first monoclonal 66% responded to the second one; the remaining 33% were mostly cases of chronic migraine with analgesic overuse.

Conclusions: In the case of adverse events switching monoclonal seems to be worthwhile as happened in our patients (no longer having unwanted secondary effects), pointing to a real different meaningful effect in the individual patient. On what concerns efficacy it may be advantageous as 66% improved but the short time of follow-up doesn´t allow to exclude latter loss of effect in the long run.