Characterization of erenumab and rimegepant on calcitonin gene-related peptide induced responses in Xenopus Laevis oocytes expressing the calcitonin gene-related peptide receptor and the amylin-1 receptor

Background The clinical use of calcitonin gene-related peptide receptor (CGRP-R) antagonists and monoclonal antibodies against CGRP and CGRP-R has offered new treatment possibilities for migraine patients. CGRP activates both the CGRP-R and structurally related amylin 1 receptor (AMY 1 -R). The relative effect of erenumab and the small-molecule CGRP-R antagonist, rimegepant, towards the CGRP-R and AMY-R needs to be further characterized. Methods The effect of CGRP and two CGRP-R antagonists were examined in Xenopus laevis oocytes expressing human CGRP-R, human AMY 1 -R and their subunits. Results CGRP administered to receptor expressing oocytes induced a concentration-dependent increase in current with the order of potency CGRP-R> > AMY 1 -R > calcitonin receptor (CTR). There was no effect on single components of the CGRP-R; calcitonin receptor-like receptor and receptor activity-modifying protein 1. Amylin was only effective on AMY 1 -R and CTR. Inhibition potencies (pIC 50 values) for erenumab on CGRP induced currents were 10.86 and 9.35 for CGRP-R and AMY 1 -R, respectively. Rimegepant inhibited CGRP induced currents with pIC 50 values of 11.30 and 9.91 for CGRP-R and AMY 1 -R, respectively. Conclusion Our results demonstrate that erenumab and rimegepant are potent antagonists of CGRP-R and AMY 1 -R with 32- and 25-times preference for the CGRP-R over the AMY 1 -R, respectively. It is discussed if this difference in affinity between the two receptors is the likely reason why constipation is a common and serious adverse effect during CGRP-R antagonism but less so with CGRP binding antibodies.