Identification of Small-Molecule Positive Modulators of Calcitonin-like Receptor-Based Receptors

Abstract

Class B G protein-coupled receptors are highly therapeutically relevant but challenges remain in identifying suitable small-molecule drugs. The calcitonin-like receptor (CLR) in particular is linked to conditions such as migraine, cardiovascular disease, and inflammatory bowel disease. The CLR cannot act as a cell-surface receptor alone but rather must couple to one of three receptor activity-modifying proteins (RAMPs), forming heterodimeric receptors for the peptides adrenomedullin and calcitonin gene-related peptide. These peptides have extended binding sites across their receptors. This is one reason why there are few small-molecule ligands that can modulate these receptors. Here we describe small molecules that are able to positively modulate the signaling of the CLR with all three RAMPs but are not active at the related calcitonin receptor. These compounds were selected from a β-arrestin recruitment screen, coupled with rounds of medicinal chemistry to improve their activity. Translational potential is shown as the compounds can positively modulate cAMP signaling in a vascular cell line model. Binding experiments do not support an extracellular domain binding site; however, molecular modeling reveals potential allosteric binding sites in multiple receptor regions. These are the first small-molecule positive modulators described for the CLR:RAMP complexes.

Pharmacological characterisation of mouse calcitonin and calcitonin receptor‐like receptors reveals differences compared with human receptors

“…This presentation approach was taken because absolute agonist potency is system dependent, and studies are more easily compared when using relative potency. Data for mouse receptors are from this paper, Husmann et al (2003) and Koller et al (2004); data for human receptors are collated from Hay et al (2018) and Garelja et al (2020) and updated to include Gingell et al (2020), and Hendrikse et al (2020). Receptor figures created with BioRender.com.…”

CGRP, adrenomedullin and adrenomedullin 2 display endogenous GPCR agonist bias in primary human cardiovascular cells

“…Additional complexity is added to the pharmacology of the CLR since it has an absolute requirement for the formation of a heterodimer with a RAMP 15,16 . In overexpression studies, each of the three RAMPs has been shown to differentially influence the affinity and agonist bias of the CGRP family of peptides at the CLR 17,18 .…”

Discovery of a First-In-Class Small Molecule Antagonist against the Adrenomedullin-2 Receptor: Structure–Activity Relationships and Optimization

“…Regardless, a number of compounds have been reported in the past decade, including synthetic modulators of glucagon, glucagon-like peptide-1, corticotropin-releasing factor 1, and calcitonin receptor-like receptors. 11 − 13 The most successful target of class B GPCRs for small molecule modulators has been the CGRP receptor (comprising CLR and RAMP1) for which several antagonists and antibodies have been developed in recent years for the treatment of migraine. 14 − 18 Some of these have reached the market including the two oral small molecule antagonists, rimegepant 19 (Nurtec ODT) and ubrogepant 20 (Ubrelvy), as well as the three injectable signal blocking monoclonal antibodies, erenumab 21 (Aimovig), eptinezumab 22 (Vyepti), and galcanezumab 23 (Emgality).…”