[Speaker] Debbie L Hay:1
[Co-author] Aqfan Jamaluddin:1, Elyse Williams:2, Margaret Brimble:2, Paul Harris:2, Christopher Walker:1, Kerry Loomes:1
1:School of Biological Sciences, The University of Auckland, New Zealand, 2:School of Chemical Sciences, The University of Auckland, New Zealand

There is high interest in blocking the actions of the neuropeptide calcitonin gene-related peptide (CGRP) for the treatment of migraine, other headache disorders, and distinct classes of pain. Small molecule antagonists and antibodies that target either CGRP itself or a CGRP receptor have been developed for clinical use. However, there are also opportunities to develop CGRP peptide antagonists. Peptide-based drugs often face difficulties with rapid degradation and clearance in circulation. However, attachment of fatty acyl residues can be a successful strategy to extend peptide half-life in vivo. Here, we developed a small library of lipidated analogues of CGRP peptide fragments and determined their pharmacology in vitro.

We used solid phase peptide synthesis and a novel approach to site-specific peptide lipidation to obtain pure peptides. These were then tested for their ability to block CGRP-stimulated cAMP production in SK-N-MC cells that express endogenous CGRP receptors and in Cos-7 cells transfected with human CGRP, AMY1, Adrenomedullin 1 (AM1) or Adrenomedullin 2 (AM2) receptors. The cells were stimulated with different concentrations of agonist in the presence of antagonist. Control antagonists were unmodified CGRP8-37 or telcagepant, a small molecule antagonist of the CGRP receptor. Data were analysed in Graphpad Prism.

Comparison of resulting pA2 or pKB values showed that novel lipidated antagonists could be obtained that had either retained or enhanced antagonist potency, compared to CGRP8-37, in a receptor-dependent manner. Lipidated peptide antagonists were identified with equivalent potency to the small molecule telcagepant.

This work provides a path forward to investigate the utility of peptide-based antagonists for the treatment of migraine and other conditions.

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