To understand whether switching from galcanezumab to fremanezumab has a continued effect

Three anti-CGRP monoclonal antibodies, galcanezumab, fremanezumab, and erenumab became available in Japan in 2021, galcanezumab was launched about four months before the other two drugs. The three drugs are administered monthly, but only fremanezumab can be administered quarterly.

We retrospectively reviewed patients who switched to fremanezumab while receiving galcanezumab at Keio University Hospital until August 2022. We focused on changes in monthly migraine days (MMD) in patients who had received fremanezumab for at least four months.

Twenty patients switched from galcanezumab to fremanezumab. The mean patient age was 47.9 years, 90% were female, and the EM:CM ratio was 9:11. Fifteen patients could be followed up on fremanezumab for more than four months. Three patients returned to galcanezumab, one patient did not reach a four-month duration within the period, and one patient was transferred to another hospital. Fifteen patients changed to fremanezumab after three to four months of treatment with galcanezumab. The reason for the changes included a side effect of alopecia during the use of galcanezumab in one patient and the desire for quarterly treatment in the other patients. Notably, thirteen of the 15 patients chose to receive quarterly dosing. The MMD was 12.3 at baseline. Mean decreases in MMD from baseline right before switching (3-4 months after galcanezumab treatment), 1 month after switching, and 4 months later are 6.9 (p = 0.002), 7.9 (p < 0.001), and 6.2 (p = 0.008), respectively. The 50% Responder Rate (RR) at four months after the switch was 67%, the 75% RR was 47%, and the 100% RR was 13% (baseline MMD was set to the baseline before galcanezumab administration).