Switching anti-CGRP monoclonal antibodies in chronic migraine: real-world observations of erenumab, fremanezumab and galcanezumab

The anti-calcitonin gene-related peptide monoclonal antibodies (anti-CGRP-mAb) are effective in migraine; however, few studies have examined the benefit of switching from one anti-CGRP-mAb to another. In order to better inform clinical practice in this situation, we present our real-world findings of switching anti-CGRP-mAb in chronic migraine.Individuals with chronic migraine that switched anti-CGRP-mAb treatment (erenumab, fremanezumab or galcanezumab) due to ineffectiveness or adverse effects were retrospectively identified. Headache diary data before and up to 6 months after anti-CGRP-mAb switch were analysed. Main outcome measures were monthly red days (days with headaches limiting activity or requiring triptans), headache days (days with any kind of headache), triptan use, other analgesic use and headache disability (Headache Impact Test-6 (HIT-6) score) at 3 months.The analysis included 66 instances of switching among 54 individuals. There were non-significant reductions of -1.2 (-2.7, 0.3) red days from baseline at 3 months, with 10 individuals (15%) showing ≥50% improvement and 22 (33%) experiencing a ≥30% improvement. Improvements in headache days, triptan days, other painkiller use and HIT-6 score were non-significant. When individuals that switched due to side effects were excluded from the analysis, significant reductions in headache (Friedman p=0.044) and a trend for improvement in red days (Friedman p=0.083) were observed. With regard to side effects, on 12 occasions these improved or resolved on switching to a different anti-CGRP-mAb, while new symptoms were reported on eight occasions following a switch.We recorded modest improvements in headache outcomes, although significant results were only observed in those that switched anti-CGRP-mAb due to ineffectiveness. Switching may therefore be a viable option for these individuals.