A novel CGRP-neutralizing Spiegelmer attenuates neurogenic plasma protein extravasation.

BACKGROUND AND PURPOSE: Calcitonin gene-related peptide (CGRP) plays an important role in the pathology of migraine, and recent clinical trials suggest the inhibition of CGRP-mediated processes as a new therapeutic option in migraine. In this study, we describe the generation of NOX-L41, a CGRP-neutralizing mirror-image (L-)aptamer (Spiegelmer) and investigate its in vitro and in vivo function. EXPERIMENTAL APPROACH: A CGRP-binding Spiegelmer was identified by in vitro selection. Binding studies were performed using surface plasmon resonance (SPR), and the inhibitory activity was determined in cell-based assays. The pharmacokinetic profile comparing i.v. and s.c. dosing was analysed in rats. Intravital two-photon microscopy was employed to follow extravasation from meningeal vessels. Finally, in vivo efficacy was tested in a model of electrically evoked meningeal plasma protein extravasation (PPE) in rats. KEY RESULTS: We identified NOX-L41, a novel CGRP-neutralizing Spiegelmer. SPR studies showed that NOX-L41 binds to human and rat/mouse CGRP with sub-nanomolar affinities and is highly selective against related peptides such as amylin. In vitro, NOX-L41 effectively inhibited CGRP-induced cAMP formation in SK-N-MC cells. In rats, NOX-L41 had a plasma half-life of 8 h. Pharmacodynamic studies showed that NOX-L41 extravasates from blood vessels in the dura mater and inhibits neurogenic meningeal PPE for at least 18 h after single dosing. CONCLUSIONS AND IMPLICATIONS: This is the first description of the CGRP-neutralizing Spiegelmer NOX-L41. Preclinical studies confirmed a role for CGRP in neurogenic PPE and provided proof-of-concept for the potential use of this new drug candidate for the treatment or prevention of migraine.

The anti-ghrelin Spiegelmer NOX-B11-3 blocks ghrelin- but not fasting-induced neuronal activation in the hypothalamic arcuate nucleus.

The hypothalamic arcuate nucleus (Arc) is the presumed target site for the orexigenic hormone ghrelin, which is secreted from the stomach during fasting. Ghrelin directly activates Arc neurones. Similar to exogenous ghrelin, overnight food deprivation also induces c-Fos expression in the Arc of mice. In the present study, we tested the role of endogenous ghrelin in the fasting-induced c-Fos expression in the Arc of mice. We used NOX-B11-3, the latest generation of the recently developed ghrelin-binding compounds, so-called RNA Spiegelmers (SPM) to block endogenous ghrelin action during food deprivation. The specificity and potency of this compound was also tested in electrophysiological and immunohistological experiments. In electrophysiological in vitro single cell recordings, NOX-B11-3 effectively blocked the excitatory effect of ghrelin in the medial Arc (ArcM) of rats whereas the biologically inactive control SPM had no effect. Furthermore, NOX-B11-3 (15 mg/kg i.p.) potently suppressed ghrelin-induced (25 microg/kg s.c., 12 h after SPM injection) c-Fos expression in the Arc. However, when injected at the beginning of a 14-h fasting period, the same dose of NOX-B11-3 had no effect on the c-Fos expression in the Arc of mice. These results demonstrate that NOX-B11-3 is a long-acting compound, which effectively blocks the effect of exogenous ghrelin on neuronal activity in the Arc under in vitro and in vivo conditions. Furthermore, increased ghrelin signalling does not appear to be a necessary factor for the activation of Arc neurones during food deprivation or other fasting-related signals might have masked or compensated for the loss of the ghrelin effect.