Background Calcitonin gene–related peptide (CGRP) may have a causative role in migraine. We therefore hypothesized that a CGRP-receptor antagonist might be effective in the treatment of migraine attacks. Methods In an international, multicenter, double-blind, randomized clinical trial of BIBN 4096 BS, a highly specific and potent nonpeptide CGRP-receptor antagonist, 126 patients with migraine received one of the following: placebo or 0.25, 0.5, 1, 2.5, 5, or 10 mg of BIBN 4096 BS intravenously over a period of 10 minutes. A group-sequential adaptive treatment-assignment design was used to minimize the number of patients exposed. Results The 2.5-mg dose was selected, with a response rate of 66 percent, as compared with 27 percent for placebo (P=0.001). The BIBN 4096 BS group as a whole had a response rate of 60 percent. Significant superiority over placebo was also observed with respect to most secondary end points: the pain-free rate at 2 hours; the rate of sustained response over a period of 24 hours; th...

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Calcitonin gene-related peptide receptor antagonist BIBN 4096 BS for the acute treatment of migraine.

Plaguing humans for more than two millennia, manifest on every continent studied, and with more than one billion patients having an attack in any year, migraine stands as the sixth most common cause of disability on the planet. The pathophysiology of migraine has emerged from a historical consideration of the "humors" through mid-20th century distraction of the now defunct Vascular Theory to a clear place as a neurological disorder. It could be said there are three questions: why, how, and when? Why: migraine is largely accepted to be an inherited tendency for the brain to lose control of its inputs. How: the now classical trigeminal durovascular afferent pathway has been explored in laboratory and clinic; interrogated with immunohistochemistry to functional brain imaging to offer a roadmap of the attack. When: migraine attacks emerge due to a disorder of brain sensory processing that itself likely cycles, influenced by genetics and the environment. In the first, premonitory, phase that precedes headache, brain stem and diencephalic systems modulating afferent signals, light-photophobia or sound-phonophobia, begin to dysfunction and eventually to evolve to the pain phase and with time the resolution or postdromal phase. Understanding the biology of migraine through careful bench-based research has led to major classes of therapeutics being identified: triptans, serotonin 5-HT1B/1D receptor agonists; gepants, calcitonin gene-related peptide (CGRP) receptor antagonists; ditans, 5-HT1F receptor agonists, CGRP mechanisms monoclonal antibodies; and glurants, mGlu5 modulators; with the promise of more to come. Investment in understanding migraine has been very successful and leaves us at a new dawn, able to transform its impact on a global scale, as well as understand fundamental aspects of human biology.

Pathophysiology of Migraine: A Disorder of Sensory Processing

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide. Discovered 30 years ago, it is produced as a consequence of alternative RNA processing of the calcitonin gene. CGRP has two major forms (α and β). It belongs to a group of peptides that all act on an unusual receptor family. These receptors consist of calcitonin receptor-like receptor (CLR) linked to an essential receptor activity modifying protein (RAMP) that is necessary for full functionality. CGRP is a highly potent vasodilator and, partly as a consequence, possesses protective mechanisms that are important for physiological and pathological conditions involving the cardiovascular system and wound healing. CGRP is primarily released from sensory nerves and thus is implicated in pain pathways. The proven ability of CGRP antagonists to alleviate migraine has been of most interest in terms of drug development, and knowledge to date concerning this potential therapeutic area is discussed. Other areas covered, where there is less information known on CGRP, include arthritis, skin conditions, diabetes, and obesity. It is concluded that CGRP is an important peptide in mammalian biology, but it is too early at present to know if new medicines for disease treatment will emerge from our knowledge concerning this molecule.

Calcitonin Gene-Related Peptide: Physiology and Pathophysiology

This review summarizes the receptor-mediated vascular activities of calcitonin gene-related peptide (CGRP) and the structurally related peptide adrenomedullin (AM). CGRP is a 37-amino acid neuropeptide, primarily released from sensory nerves, whilst AM is produced by stimulated vascular cells, and amylin is secreted from the pancreas. They share vasodilator activity, albeit to varying extents depending on species and tissue. In particular, CGRP has potent activity in the cerebral circulation, which is possibly relevant to the pathology of migraine, whilst vascular sources of AM contribute to dysfunction in cardiovascular disease. Both peptides exhibit potent activity in microvascular beds. All three peptides can act on a family of CGRP receptors that consist of calcitonin receptor-like receptor (CL) linked to one of three receptor activity-modifying proteins (RAMPs) that are essential for functional activity. The association of CL with RAMP1 produces a CGRP receptor, with RAMP2 an AM receptor and with RAMP3 a CGRP/AM receptor. Evidence for the selective activity of the first nonpeptide CGRP antagonist BIBN4096BS for the CGRP receptor is presented. The cardiovascular activity of these peptides in a range of species and in human clinical conditions is detailed, and potential therapeutic applications based on use of antagonists and gene targeting of agonists are discussed.

https://www.physiology.org/doi/pdf/10.1152/physrev.00037.2003

Vascular Actions of Calcitonin Gene-Related Peptide and Adrenomedullin

BackgroundWe tested erenumab, a fully human monoclonal antibody that inhibits the calcitonin gene–related peptide receptor, for the prevention of episodic migraine. MethodsWe randomly assigned patients to receive a subcutaneous injection of either erenumab, at a dose of 70 mg or 140 mg, or placebo monthly for 6 months. The primary end point was the change from baseline to months 4 through 6 in the mean number of migraine days per month. Secondary end points were a 50% or greater reduction in mean migraine days per month, change in the number of days of use of acute migraine–specific medication, and change in scores on the physical-impairment and everyday-activities domains of the Migraine Physical Function Impact Diary (scale transformed to 0 to 100, with higher scores representing greater migraine burden on functioning). ResultsA total of 955 patients underwent randomization: 317 were assigned to the 70-mg erenumab group, 319 to the 140-mg erenumab group, and 319 to the placebo group. The mean number of ...

A Controlled Trial of Erenumab for Episodic Migraine.

Calcitonin gene-related peptide (CGRP) has been detected in increased amounts in external jugular venous blood during migraine attacks. However, it is unknown whether this is secondary to migraine or whether CGRP may cause headache. In a double-blind crossover study, the effect of human alphaCGRP (2 microg/min) or placebo infused intravenously for 20 min was studied in 12 patients suffering from migraine without aura. Headache intensity was scored on a scale from 0 to 10. Two patients were excluded due to severe hypotension and one because she had an infection. In the first hour median peak headache score was 1.0 in the halphaCGRP group vs. 0 in the placebo group (P < 0.01). During the following 11 h all patients experienced headaches after halphaCGRP vs. one patient after placebo (P = 0.0004). The median maximal headache score was 4 after CGRP and 0 after placebo (P = 0.006). In three patients after halphaCGRP, but in no patients after placebo, the delayed headache fulfilled the IHS criteria for migraine without aura. As intravenous administration of halphaCGRP causes headache and migraine in migraineurs, our study suggests that the increase in CGRP observed during spontaneous migraine attacks may play a causative role.

CGRP may play a causative role in migraine

Calcitonin gene-related peptide (CGRP)-containing nerves are closely associated with cranial blood vessels. CGRP is the most potent vasodilator known in isolated cerebral blood vessels. CGRP can induce migraine attacks, and two selective CGRP receptor antagonists are effective in the treatment of migraine attacks. It is therefore important to investigate its mechanism of action in patients with migraine. We here investigate the effects of intravenous human alpha-CGRP (hαCGRP) on intracranial hemodynamics. In a double-blind, cross-over study, the effect of intravenous infusion of hαCGRP (2 μg/min) or placebo for 20 min was studied in 12 patients with migraine without aura outside attacks. Xenon-133 inhalation SPECT-determined regional cerebral blood flow (rCBF) and transcranial Doppler (TCD)-determined blood velocity (Vmean) in the middle cerebral artery (MCA), as well as the heart rate and blood pressure, were the outcome parameters. No change of rCBF was observed at the end of infusion [1.2% ± 1.7 with hαCGRP, vs. −1.6% ± 3.1 with placebo (mean ± SD)] (P = 0.43). Vmean in MCA decreased to 13.5% ± 3.6 with hαCGRP versus 0.6% ± 1.8 with placebo (P < 0.005). Since rCBF was unchanged, this indicates a dilation of the MCA. hαCGRP induced a decrease in MAP (12%) (P < 0.005) and an increase in heart rate (58%) (P < 0.0001). CGRP dilates cerebral arteries, but the effect is so small that it is unlikely to be the only mechanism of CGRP-induced migraine.

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Involvement of calcitonin gene-related peptide in migraine: regional cerebral blood flow and blood flow velocity in migraine patients.

Patients with pheochromocytoma and paraganglioma (PPGL) are treated with α-adrenoceptor antagonists to improve peroperative hemodynamics. However, preoperative blood pressure targets differ between institutions. We retrospectively compared per- and postoperative hemodynamics in 30 patients with PPGL that were pretreated with phenoxybenzamine aiming at different blood pressure targets at two separate endocrine departments. All patients were subsequently undergoing laparoscopic surgery at Department of Urology, Herlev University hospital. Fourteen patients were treated targeting to symptomatic and significant orthostatic hypotension and 16 patients to a seated blood pressure below 130/80 mmHg. As a control group, we included 34 patients undergoing laparoscopic adrenalectomy for other reasons. The group titrated to orthostatic hypotension required a higher dose of phenoxybenzamine to achieve the blood pressure target. This group had less intraoperative systolic and diastolic blood pressure fluctuation (Mann–Whitney U test; P  < 0.05) and less periods with heart rate above 100 b.p.m. (Mann–Whitney U test; P = 0.04) as compared to the group with a preoperative blood pressure target below 130/80 mmHg. Peroperative use of intravenous fluids were similar between the two groups, but postoperatively more intravenous fluids were administered in the group with a target of ortostatism. Overall, the control group was more hemodynamic stable as compared to either group treated for PPGL. We conclude that phenoxybenzamine pretreatment targeting ortostatic hypotension may improve peroperative hemodynamic stability but causes a higher postoperative requirement for intravenous fluids. Overall, PPGL surgery is related to greater hemodynamic instability compared to adrenalectomy for other reasons.

P A Haderslev

Papers

CGRP may play a causative role in migraine

Involvement of calcitonin gene-related peptide in migraine: regional cerebral blood flow and blood flow velocity in migraine patients.

Preoperative blood pressure targets and effect on hemodynamics in pheochromocytoma and paraganglioma