Effect of Calcitonin Gene-Related Peptide Receptor Antagonism on the Systemic Blood Pressure Responses to Mechanistically Diverse Vasomodulators in Conscious Rats

Fremanezumab as a preventive treatment for episodic and chronic migraine

Introduction: The importance of calcitonin gene-related peptide (CGRP) in migraine pathogenesis is well established. Fremanezumab is a humanized IgG2a monoclonal antibody that binds to CGRP. Areas covered: In this paper, we review the development of fremanezumab, from early development into approval. The authors focus on the efficacy and safety of fremanezumab in both migraine stages. The authors highlight studies conducted in special populations and focus on unique aspects of its development, as well as on clinical pearls supported by the data. Expert opinion: Fremanezumab was shown to be effective in episodic and chronic migraine, with a monthly and quarterly dose of administration, as monotherapy and add-on therapy. As with other monoclonal antibodies, the anti-CGRP onset of action was remarkably quick, and the effect seems to be maintained over time. No overt safety concerns emerged from the clinical studies, although long-term surveillance is necessary.

Nonclinical safety evaluation of erenumab, a CGRP receptor inhibitor for the prevention of migraine

Calcitonin gene-related peptide (CGRP) and its receptor have been implicated as a key mediator in the pathophysiology of migraine. Thus, erenumab, a monoclonal antibody antagonist of the CGRP receptor, administered as a once monthly dose of 70 or 140 mg has been approved for the preventive treatment of migraine in adults. Due to the species specificity of erenumab, the cynomolgus monkey was used in the pharmacology, pharmacokinetics, and toxicology studies to support the clinical program. There were no effects of erenumab on platelets in vitro (by binding, activation or phagocytosis assays). Specific staining of human tissues with erenumab did not indicated any off-target binding. There were no erenumab-related findings in a cardiovascular safety pharmacology study in cynomolgus monkeys or in vitro in human isolated coronary arteries. Repeat-dose toxicology studies conducted in cynomolgus monkeys at dose levels up to 225 mg/kg (1 month) or up to 150 mg/kg (up to 6 months) with twice weekly subcutaneous (SC) doses showed no evidence of erenumab-mediated adverse toxicity. There were no effects on pregnancy, embryo-fetal or postnatal growth and development in an enhanced pre-postnatal development study in the cynomolgus monkey. There was evidence of placental transfer of erenumab based on measurable serum concentrations in the infants up to 3 months post birth. The maternal and developmental no-observed-effect level (NOEL) was the highest dose tested (50 mg/kg SC Q2W). These nonclinical data in total indicate no safety signal of concern to date and provide adequate margins of exposure between the observed safe doses in animals and clinical dose levels.

Calcitonin Gene-Related Peptide Modulators - The History and Renaissance of a New Migraine Drug Class

Several lines of evidence pointed to an important role for CGRP in migraine. These included the anatomic colocalization of CGRP and its receptor in sensory fibers innervating pain-producing meningeal blood vessels, its release by trigeminal stimulation, the observation of elevated CGRP in the cranial circulation during migraine with normalization concomitant with headache relief by sumatriptan, and translational studies with intravenous (IV) CGRP that evoked migraine only in migraineurs. The development of small molecule CGRP receptor antagonists (CGRP-RAs) that showed clinical antimigraine efficacy acutely and prophylactically in randomized placebo-controlled clinical trials subsequently gave definitive pharmacological proof of the importance of CGRP in migraine. More recently, CGRP target engagement imaging studies using a CGRP receptor PET ligand [¹¹ C]MK-4232 demonstrated that there was no brain CGRP receptor occupancy at clinically effective antimigraine doses of telcagepant, a prototypic CGRP-RA. Taken together, these data indicated that (1) the therapeutic site of action of the CGRP-RAs was peripheral not central; (2) that IV CGRP had most likely evoked migraine through an action at sites outside the blood-brain barrier; and (3) that migraine pain was therefore, at least in part, peripheral in origin. The evolution of CGRP migraine science gave impetus to the development of peripherally acting drugs that could modulate CGRP chronically to prevent frequent episodic and chronic migraine. Large molecule biologic antibody (mAb) approaches that are given subcutaneously to neutralize circulating CGRP peptide (fremanezumab, galcanezumab) or block CGRP receptors (erenumab) have shown consistent efficacy and tolerability in multicenter migraine prevention trials and are now approved for clinical use. Eptinezumab, a CGRP neutralizing antibody given IV, shows promise in late stage clinical development. Recently, orally administered next-generation small molecule CGRP-RAs have been shown to have safety and efficacy in acute treatment (ubrogepant and rimegepant) and prevention (atogepant) of migraine, giving additional CGRP-based therapeutic options for migraine patients.

From LBR-101 to Fremanezumab for Migraine

Calcitonin gene-related peptide (CGRP) is a neuropeptide of importance in migraine pathogenesis. Its central role in migraine was proven pharmacologically by the development of CGRP receptor antagonists. Monoclonal antibodies targeting CGRP or its receptor are effective in the preventive treatment of episodic and chronic migraine and are considered potential breakthroughs in their treatment. Fremanezumab (previously known as TEV-48125, LBR-101, or RN-307) is a humanized IgG2a monoclonal antibody that binds to CGRP. The development of this antibody validated the role of CGRP in chronic migraine and the drug has been recently approved in the US by the FDA, while it continues to be reviewed by other regulatory agencies. Herein we provide an in-depth review of its development. We start by summarizing its in vitro and in vivo pharmacology, and the phase I studies. We then review the late-stage clinical development, with a focus on its efficacy, safety, similarities, and uniqueness relative to other CGRP antibodies. We close by discussing lessons learned on the mechanisms of migraine and areas for future development and exploration.

Redox Mechanisms in Migraine: Novel Therapeutics and Dietary Interventions

SIGNIFICANCE

Migraine represents the third most prevalent and the seventh most disabling human disorder. Approximately 30% of migraine patients experience transient, fully reversible, focal neurological symptoms (aura) preceding the attack. Recent Advances: Awareness of the hypothesis that migraine actually embodies a spectrum of illnesses-ranging from episodic to chronic forms-is progressively increasing and poses novel challenges for clarifying the underlying pathophysiological mechanisms of migraine as well as for the development of novel therapeutic interventions. Several theories have evolved to the current concept that a combination of genetic, epigenetic, and environmental factors may play a role in migraine pathogenesis, although their relative importance is still being debated.

CRITICAL ISSUES

One critical issue that deserves a particular attention is the role of oxidative stress in migraine. Indeed, potentially harmful oxidative events occur during the migraine attack and long-lasting or frequent migraine episodes may increase brain exposure to oxidative events that can lead to chronic transformation. Moreover, a wide variety of dietary, environmental, physiological, behavioral, and pharmacological migraine triggers may act through oxidative stress, with clear implications for migraine treatment and prophylaxis. Interestingly, almost all current prophylactic migraine agents exert antioxidant effects.

FUTURE DIRECTIONS

Increasing awareness of the role of oxidative stress and/or decreased antioxidant defenses in migraine pathogenesis and progression to a chronic condition lays the foundations for the design of novel prophylactic approaches, which, by reducing brain oxidative phenomena, could favorably modify the clinical course of migraine. Antioxid. Redox Signal. 28, 1144-1183.

Evaluation of cardiovascular parameters in cynomolgus monkeys following IV administration of LBR-101, a monoclonal antibody against calcitonin gene-related peptide

Calcitonin gene-related peptide (CGRP) is a well-validated target for migraine therapy and a known potent systemic vasodilator. LBR-101 is a monoclonal antibody against CGRP in clinical development for the preventive treatment of episodic and chronic migraine. Understanding the hemodynamic and cardiovascular consequences of chronic CGRP inhibition is therefore warranted. Given the conservation in CGRP sequence between monkeys and humans, addressing this question in monkeys is ideal as it allows dosing at super-therapeutic levels. To this end, two independent studies were conducted in monkeys: a single dedicated cardiovascular safety study and a repeat-dose, chronic study, both with electrocardiogram and hemodynamic assessments. LBR-101 was very well tolerated in both studies, with no clinically significant changes noted in any hemodynamic parameter, nor any relevant changes noted in any ECG parameter. In cynomolgus monkeys, cardiovascular and hemodynamic parameters do not appear to be affected by long-term inhibition of CGRP with LBR-101.

Cardiovascular and hemodynamic parameters in women following prolonged CGRP inhibition using LBR-101, a monoclonal antibody against CGRP

BACKGROUND

The vascular effects of acute calcitonin gene-related peptide (CGRP) inhibition are well described, but the effects of sustained inhibition warrant further exploration in humans.

OBJECTIVES

The objective of this article is to assess the effects of sustained CGRP inhibition on blood pressure, heart rate, and ECGs in healthy women ≥ 40 years of age.

METHODS

In this double-blind, placebo-controlled study, 31 women (mean age = 56) were randomized to receive placebo or an anti-CGRP monoclonal antibody at doses up to 2000 mg. Participants were confined for seven days and followed for 168 days. Cardiac telemetry was conducted for eight hours after infusion completion. Hemodynamic assessments and ECGs were conducted six times during Day 1 and periodically for three months.

RESULTS

No clinically relevant changes in systolic or diastolic blood pressure, heart rate, or ECG parameters (RR, PR, QRS, or QTcF) were observed when comparing baseline vs. post-dose time-points or in-between groups. No significant changes were seen for adjusted QTcF (baseline subtracted and placebo and baseline subtracted). No significant differences or relevant abnormalities were seen when comparing parameters obtained at Tmax vs. any other time-point.

CONCLUSION

Sustained CGRP inhibition was not associated with hemodynamic or ECG changes in a population at an increased age risk for cardiovascular events.

Effect of telcagepant on spontaneous ischemia in cardiovascular patients in a randomized study

OBJECTIVE

The primary purpose of the study was to explore the safety and tolerability of telcagepant in patients with stable coronary artery disease.

BACKGROUND

Triptans are effective acute anti-migraine drugs whose vasoconstrictive effects limit their use in patients at risk for adverse cardiovascular events. Telcagepant, a calcitonin gene-related peptide receptor antagonist, is being developed for the acute treatment of migraine. Antagonism of calcitonin gene-related peptide, which does not appear to cause vasoconstriction, may allow for treatment of migraine in patients with coronary artery disease.

METHODS

In this randomized, double-blind, placebo-controlled, crossover study, patients with documented stable coronary artery disease were assigned to 1 of 2 treatment sequences: telcagepant then placebo, or placebo then telcagepant. In each treatment period, patients received 2 doses of telcagepant 300-mg or placebo 2 hours apart. They remained in the research center for 24 hours after receiving the first dose of each period, during which time continuous 12-lead ambulatory electrocardiographic (Holter) monitoring was performed.

RESULTS

Twenty-eight patients were enrolled; all patients completed the study and were included in all analyses. Telcagepant was generally well tolerated. No laboratory or serious adverse experiences were reported, and no patient discontinued due to an adverse experience. There were no consistent treatment-related changes in laboratory, vital signs or electrocardiogram safety parameters. Three patients (2 after receiving placebo and 1 after receiving telcagepant) experienced ST segment depression during the study; none of these patients reported chest pain.

CONCLUSIONS

Two doses of 300-mg telcagepant, administered 2 hours apart, did not appear to exacerbate spontaneous ischemia and were generally well tolerated in a small cohort of patients with stable coronary artery disease. Results of this study support further evaluation of telcagepant in patients with stable coronary artery disease.

A randomized, placebo-controlled study of the effects of telcagepant on exercise time in patients with stable angina

Telcagepant is a calcitonin gene-related peptide (CGRP) receptor antagonist being evaluated for acute migraine treatment. CGRP is a potent vasodilator that is elevated after myocardial infarction, and it delays ischemia during treadmill exercise. We tested the hypothesis that CGRP receptor antagonism does not reduce treadmill exercise time (TET). The effects of supratherapeutic doses of telcagepant on TET were assessed in a double-blind, randomized, placebo-controlled, two-period, crossover study in patients with stable angina and reproducible exercise-induced angina. Patients received telcagepant (600 mg, n = 46; and 900 mg, n = 14) or placebo and performed treadmill exercise at T(max) (2.5 h after the dose). The hypothesis that telcagepant does not reduce TET was supported if the lower bound of the two-sided 90% confidence interval (CI) for the mean treatment difference (telcagepant-placebo) in TET was more than -60 s. There were no significant between-treatment differences in TET (mean treatment difference: -6.90 (90% CI: -17.66, 3.86) seconds), maximum exercise heart rate, or time to 1-mm ST-segment depression using pooled data or with stratification for dose.

Randomized, controlled study of telcagepant in patients with migraine and coronary artery disease

OBJECTIVE

To evaluate the efficacy of telcagepant in patients with migraine and coronary artery disease.

BACKGROUND

Calcitonin gene-related peptide receptor antagonists, such as telcagepant, may be useful for acute migraine treatment in patients with cardiovascular disease, a population for whom triptans are contraindicated.

METHODS

Randomized, double-blind, two-period (6 weeks per period) crossover study in patients with stable coronary artery disease and migraine. Patients were randomized 1:1 to either: (1) Period 1: telcagepant (280-mg tablet/300-mg capsule), Period 2: acetaminophen (1000-mg); or (2) Period 1: placebo for attack 1 then acetaminophen for subsequent attacks, Period 2: telcagepant. Patients could treat up to 12 migraine attacks per period to assess the tolerability of telcagepant. The primary efficacy analysis evaluated telcagepant vs placebo on 2-hour pain freedom during the first attack of Period 1.

RESULTS

One hundred and sixty-five of the planned 400 patients were enrolled, and 114 took at least one dose of treatment. Telcagepant was not statistically different from placebo for 2-hour pain freedom (25.0% vs 18.9%, odds ratio = 1.62 [95% confidence interval: 0.62, 4.25]). The median number of attacks treated per period was 3. No cardiovascular thrombotic adverse events occurred within 14 days of dosing.

CONCLUSION

The study was underpowered due to enrollment difficulties and did not demonstrate a significant efficacy difference between telcagepant and placebo for the treatment of a migraine attack in patients with stable coronary artery disease. Telcagepant was generally well tolerated for acute intermittent migraine treatment in these patients.

Characterization of the calcitonin gene-related peptide receptor antagonist telcagepant (MK-0974) in human isolated coronary arteries

The sensory neuropeptide calcitonin gene-related peptide (CGRP) plays a role in primary headaches, and CGRP receptor antagonists are effective in migraine treatment. CGRP is a potent vasodilator, raising the possibility that antagonism of its receptor could have cardiovascular effects. We therefore investigated the effects of the antimigraine CGRP receptor antagonist telcagepant (MK-0974) [N-[(3R,6S)-6-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)azepan-3-yl]-4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridine-1-yl)piperidine-1-carboxamide] on human isolated coronary arteries. Arteries with different internal diameters were studied to assess the potential for differential effects across the coronary vascular bed. The concentration-dependent relaxation responses to human alphaCGRP were greater in distal coronary arteries (i.d. 600-1000 microm; E(max) = 83 +/- 7%) than proximal coronary arteries (i.d. 2-3 mm; E(max) = 23 +/- 9%), coronary arteries from explanted hearts (i.d. 3-5 mm; E(max) = 11 +/- 3%), and coronary arterioles (i.d. 200-300 microm; E(max) = 15 +/- 7%). Telcagepant alone did not induce contraction or relaxation of these coronary blood vessels. Pretreatment with telcagepant (10 nM to 1 microM) antagonized alphaCGRP-induced relaxation competitively in distal coronary arteries (pA(2) = 8.43 +/- 0.24) and proximal coronary arteries and coronary arterioles (1 microM telcagepant, giving pK(B) = 7.89 +/- 0.13 and 7.78 +/- 0.16, respectively). alphaCGRP significantly increased cAMP levels in distal, but not proximal, coronary arteries, and this was abolished by pretreatment with telcagepant. Immunohistochemistry revealed the expression and colocalization of the CGRP receptor elements calcitonin-like receptor and receptor activity-modifying protein 1 in the smooth muscle cells in the media layer of human coronary arteries. These findings in vitro support the cardiovascular safety of CGRP receptor antagonists and suggest that telcagepant is unlikely to induce coronary side effects under normal cardiovascular conditions.