BMS-927711 for the acute treatment of migraine: a double-blind, randomized, placebo controlled, dose-ranging trial

CGRP, a target for preventive therapy in migraine and cluster headache: Systematic review of clinical data

Introduction

Migraine and cluster headache are challenging to manage, with no tailored preventive medications available. Targeting the calcitonin gene-related peptide (CGRP) pathway to treat these headaches may be the first focused therapeutic option to date, with the potential for promising efficacy.

Methods

We systematically searched PubMed and clinicaltrials.gov for randomized controlled trials investigating the preventive potential of monoclonal antibodies against the CGRP pathway in the treatment of migraine and cluster headache.

Results

The literature search returned a total of 136 records, of which 32 were eligible for review.

Discussion

Clinical data from phase II and III trials of the four monoclonal antibodies targeting the CGRP pathway: Eptinezumab, erenumab, fremanezumab, and galcanezumab, collectively show a positive effect in the preventive treatment of episodic and chronic migraine. Multiple phase II and III trials are under way to further determine the efficacy and safety of this new drug class. It may be particularly important to assess the cardiovascular effects of long-term CGRP blockade. Phase III trials are also currently in progress for the preventive treatment of cluster headache.

Conclusion

Efficacy of anti-CGRP monoclonal antibodies spells a promising future for the many patients suffering from migraine, and possibly also for the smaller but severely-affected population with cluster headache.

Blocking CGRP in migraine patients - a review of pros and cons

Migraine is the most prevalent neurological disorder worldwide and it has immense socioeconomic impact. Currently, preventative treatment options for migraine include drugs developed for diseases other than migraine such as hypertension, depression and epilepsy. During the last decade, however, blocking calcitonin gene-related peptide (CGRP) has emerged as a possible mechanism for prevention of migraine attacks. CGRP has been shown to be released during migraine attacks and it may play a causative role in induction of migraine attacks. Here, we review the pros and cons of blocking CGRP in migraine patients. To date, two different classes of drugs blocking CGRP have been developed: small molecule CGRP receptor antagonists (gepants), and monoclonal antibodies, targeting either CGRP or the CGRP receptor. Several trials have been conducted to test the efficacy and safety of these drugs. In general, a superior efficacy compared to placebo has been shown, especially with regards to the antibodies. In addition, the efficacy is in line with other currently used prophylactic treatments. The drugs have also been well tolerated, except for some of the gepants, which induced a transient increase in transaminases. Thus, blocking CGRP in migraine patients is seemingly both efficient and well tolerated. However, CGRP and its receptor are abundantly present in both the vasculature, and in the peripheral and central nervous system, and are involved in several physiological processes. Therefore, blocking CGRP may pose a risk in subjects with comorbidities such as cardiovascular diseases. In addition, long-term effects are still unknown. Evidence from animal studies suggests that blocking CGRP may induce constipation, affect the homeostatic functions of the pituitary hormones or attenuate wound healing. However, these effects have so far not been reported in human studies. In conclusion, this review suggests that, based on current knowledge, the pros of blocking CGRP in migraine patients exceed the cons.

An update on migraine: current understanding and future directions

Migraine is a common brain disorder with high disability rates which involves a series of abnormal neuronal networks, interacting at different levels of the central and peripheral nervous system. An increase in the interest around migraine pathophysiology has allowed researchers to unravel certain neurophysiological mechanisms and neurotransmitter involvement culminating in the recent development of novel therapies, which might substantially change the clinical approach to migraine patients. The present review will highlight the current aspects of migraine pathophysiology, covering an understanding of the complex workings of the migraine state and the brain regions responsible for them. We will further discuss the therapeutic agents which have appeared in the most recent years for migraine care, from calcitonin gene-related peptide (CGRP) receptor antagonists, gepants; through serotonin 5-HT1F receptor agonists, ditans, and CGRP or CGRP receptor monoclonal antibodies to invasive and non-invasive neuromodulation techniques.

Practical characteristics of adaptive design in phase 2 and 3 clinical trials

WHAT IS KNOWN AND OBJECTIVE

Adaptive design methods are expected to be ethical, reflect real medical practice, increase the likelihood of research and development success and reduce the allocation of patients into ineffective treatment groups by the early termination of clinical trials. However, the comprehensive details regarding which types of clinical trials will include adaptive designs remain unclear. We examined the practical characteristics of adaptive design used in clinical trials.

METHODS

We conducted a literature search of adaptive design clinical trials published from 2012 to 2015 using PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials, with common search terms related to adaptive design. We systematically assessed the types and characteristics of adaptive designs and disease areas employed in the adaptive design trials.

RESULTS AND DISCUSSION

Our survey identified 245 adaptive design clinical trials. The number of trials by the publication year increased from 2012 to 2013 and did not greatly change afterwards. The most frequently used adaptive design was group sequential design (n = 222, 90.6%), especially for neoplasm or cardiovascular disease trials. Among the other types of adaptive design, adaptive dose/treatment group selection (n = 21, 8.6%) and adaptive sample-size adjustment (n = 19, 7.8%) were frequently used. The adaptive randomization (n = 8, 3.3%) and adaptive seamless design (n = 6, 2.4%) were less frequent. Adaptive dose/treatment group selection and adaptive sample-size adjustment were frequently used (up to 23%) in "certain infectious and parasitic diseases," "diseases of nervous system," and "mental and behavioural disorders" in comparison with "neoplasms" (<6.6%). For "mental and behavioural disorders," adaptive randomization was used in two trials of eight trials in total (25%). Group sequential design and adaptive sample-size adjustment were used frequently in phase 3 trials or in trials where study phase was not specified, whereas the other types of adaptive designs were used more in phase 2 trials. Approximately 82% (202 of 245 trials) resulted in early termination at the interim analysis. Among the 202 trials, 132 (54% of 245 trials) had fewer randomized patients than initially planned. This result supports the motive to use adaptive design to make study durations shorter and include a smaller number of subjects.

WHAT IS NEW AND CONCLUSION

We found that adaptive designs have been applied to clinical trials in various therapeutic areas and interventions. The applications were frequently reported in neoplasm or cardiovascular clinical trials. The adaptive dose/treatment group selection and sample-size adjustment are increasingly common, and these adaptations generally follow the Food and Drug Administration's (FDA's) recommendations.

Anti-CGRP Monoclonal Antibodies: the Next Era of Migraine Prevention?

OPINION STATEMENT

Migraine is a very disabling disorder with severe impact on patients' lives and substantive costs to society in terms of healthcare costs and lost productivity. Prevention is a key component of migraine therapy, and while numerous preventive options exist, each is burdened by either troublesome side effects or insufficient efficacy. All migraine preventives currently in clinical use were licensed for other purposes and, by chance, have efficacy against migraine. As our understanding of migraine has evolved, calcitonin gene-related peptide (CGRP) has moved to the forefront as a neuropeptide central to migraine pathophysiology. Six small molecule CGRP receptor antagonists were shown to be effective for acute treatment of migraine; two were stopped for hepatotoxicity or one for formulation concern issues and one is now in phase III. Monoclonal antibodies against CGRP or the CGRP receptor have a longer duration of action and have been investigated for migraine prevention. Four are in development and three have completed phase II and one phase III trials; every reported study has been positive. Furthermore, no safety issues have arisen to date, including hepatic or cardiovascular effects, and initial tolerability appears to be excellent. Monoclonal antibodies antagonizing the CGRP pathway represent a novel approach to prevention: a mechanism-specific migraine-targeted therapy. While we must await the results of all the phase III trials, cautious excitement seems warranted as we enter a new era of better tolerated, well-understood, bespoke migraine treatment for this common and disabling neurological disorder.

Spotlight on Anti-CGRP Monoclonal Antibodies in Migraine: The Clinical Evidence to Date

Migraine, a common neurovascular brain disorder, represents a severe and widespread health problem; along with medication‐induced (medication‐overuse) headache, it is the third‐leading cause of disability worldwide. Currently, its therapeutic management remains unsatisfactory for several reasons; up to 40% of migraineurs are eligible for prophylactic treatment, but there are issues of efficacy, safety, and adherence. In recent years the evidence on the role of calcitonin gene‐related peptide (CGRP) in migraine pathophysiology has been consolidated, so new and promising treatments for migraine pain and its possible prevention have been developed. The following review reports the results of the clinical trials conducted so far with each of the new monoclonal antibodies targeting CGRP or its receptor, with particular reference to safety, tolerance, and efficacy in migraine prevention. Moreover, the pharmacological characterization and further developments of each monoclonal antibody are reported, based on current knowledge.

Asymmetric Synthesis of the Major Metabolite of a Calcitonin Gene-Related Peptide Receptor Antagonist and Mechanism of Epoxide Hydrogenolysis

An asymmetric synthesis of the major metabolite of the calcitonin gene-related peptide recepotor antagonist BMS-846372 is presented. The variously substituted cyclohepta[b]pyridine ring system represents an underexplored ring system and showed some unexpected chemistry. Reactivities of epoxide and ketone functional groups on the cycloheptane ring were extensively controlled by a remote bulky TIPS group. The rate difference of the hydrogenolysis between two diastereomeric epoxide intermediates shed some light on the mechanism of epoxide hydrogenolysis, and further, deuterium labeling studies revealed more mechanistic details on this well-known chemical transformation for the first time.

The role of calcitonin gene-related peptide in peripheral and central pain mechanisms including migraine

Calcitonin gene-related peptide (CGRP) is a 37-amino acid peptide found primarily in the C and Aδ sensory fibers arising from the dorsal root and trigeminal ganglia, as well as the central nervous system. Calcitonin gene-related peptide was found to play important roles in cardiovascular, digestive, and sensory functions. Although the vasodilatory properties of CGRP are well documented, its somatosensory function regarding modulation of neuronal sensitization and of enhanced pain has received considerable attention recently. Growing evidence indicates that CGRP plays a key role in the development of peripheral sensitization and the associated enhanced pain. Calcitonin gene-related peptide is implicated in the development of neurogenic inflammation and it is upregulated in conditions of inflammatory and neuropathic pain. It is most likely that CGRP facilitates nociceptive transmission and contributes to the development and maintenance of a sensitized, hyperresponsive state not only of the primary afferent sensory neurons but also of the second-order pain transmission neurons within the central nervous system, thus contributing to central sensitization as well. The maintenance of a sensitized neuronal condition is believed to be an important factor underlying migraine. Recent successful clinical studies have shown that blocking the function of CGRP can alleviate migraine. However, the mechanisms through which CGRP may contribute to migraine are still not fully understood. We reviewed the role of CGRP in primary afferents, the dorsal root ganglion, and in the trigeminal system as well as its role in peripheral and central sensitization and its potential contribution to pain processing and to migraine.

Pathophysiology of Migraine: A Disorder of Sensory Processing

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.

Binding and functional pharmacological characteristics of gepant-type antagonists in rat brain and mesenteric arteries

AIM

The neuropeptide calcitonin gene-related peptide (CGRP) is found in afferent sensory nerve fibers innervating the resistance arteries and plays a pivotal role in a number of neurovascular diseases such as migraine and subarachnoid bleedings. The present study investigates the binding and antagonistic characteristics of small non-peptide CGRP receptor antagonists (i.e. gepants) in isolated rat brain and mesenteric resistance arteries.

METHODS

The antagonistic behavior of gepants was investigated in isolated rat mesenteric arteries using a wire myograph setup while binding of gepants to CGRP receptors was investigated in rat brain membranes using a radioligand competitive binding assay. Furthermore, the histological location of the key components of CGRP receptor (RAMP1 and CLR) was assessed by immunohistochemistry.

RESULTS

Our functional studies clearly show that all gepants are reversible competitive antagonists producing Schild plot slopes not significantly different from unity and thus suggesting presence of a uniform CGRP receptor population in the arteries. A uniform receptor population was also confirmed by radioligand competitive binding studies showing similar affinities for the gepants in rat brain and mesenteric arteries, the exception being rimegepant which had 50-fold lower affinity in brain than mesenteric arteries. CLR and RAMP1 were shown to be located in both vascular smooth muscle and endothelial cells of rat mesenteric arteries by immunohistochemistry.

CONCLUSION

The present results indicate that, despite species differences in the CGRP receptor affinity, the antagonistic nature of these gepants, the distribution pattern of CGRP receptor components and the mechanism behind CGRP-induced vasodilation seem to be similar in resistance-sized arteries of human and rats.

Minority Representation in Migraine Treatment Trials

BACKGROUND

Minorities have historically been underrepresented in clinical research trials despite having comparatively poor health indicators. Recognizing the dual inequalities of increased disease burden and decreased research participation, the National Institute of Health (NIH) Revitalization Act of 1993 mandated the inclusion and reporting of women and minorities in NIH-funded research. While progress has been made in the subsequent decades, this underrepresentation of minorities in research trials persists and has been documented in multiple disciplines. However, the extent of adequate representation and reporting of minority inclusion in clinical trials for migraine remains unknown.

OBJECTIVES

In this systematic review and study, we review the literature examining the representation of women and minorities in migraine clinical research trials METHODS: First we searched PubMed for pertinent articles examining the inclusion of women and minorities in migraine clinical research trials. Second, we identified controlled-trials for migraine published since 2011 in major neurology, headache, and general medicine journals using the terms "migraine randomized controlled trial." We then reviewed the results manually and excluded pilot studies and those with fewer than 50 participants. We next determined (a) how frequently representation of minorities and women were reported in these major trials; (b) what factors correlated with reporting; and (c) whether women and minority inclusion comprised their ratios in the general population.

RESULTS

We identified 128 relevant clinical trials, of which 36 met our inclusion criteria. All 36 trials (100%) reported gender frequency, and 25 of 36 (69.4%) reported ethnicity or race. Among all studies, women and Whites represented 84.2 and 82.9% of participants (mean), respectively. Studies conducted in the United States and funded by a private company were more likely to report race than studies conducted exclusively outside of the U.S. or with a public sponsor. No studies stratified efficacy or safety by ethnicity or gender. Men and non-Whites in the U.S. were statistically underrepresented.

CONCLUSIONS

Most recent headache studies comply with the NIH mandate to include women and minorities in research trials, particularly U.S.-based and industry-funded studies. Whites are overrepresented compared to both the general population and the population of migraineurs. Future studies should strive to increase minority participation and investigate race-based differences in migraine expression, treatment response, and medication toxicity.

Transmission pathways and mediators as the basis for clinical pharmacology of pain

INTRODUCTION

Mediators in pain transmission are the targets of a multitude of different analgesic pharmaceuticals. This review explores the most significant mediators of pain transmission as well as the pharmaceuticals that act on them. Areas covered: The review explores many of the key mediators of pain transmission. In doing so, this review uncovers important areas for further research. It also highlights agents with potential for producing novel analgesics, probes important interactions between pain transmission pathways that could contribute to synergistic analgesia, and emphasizes transmission factors that participate in transforming acute injury into chronic pain. Expert commentary: This review examines current pain research, particularly in the context of identifying novel analgesics, highlighting interactions between analgesic transmission pathways, and discussing factors that may contribute to the development of chronic pain after an acute injury.

A phase IIb randomized, double-blind, placebo-controlled trial of ubrogepant for the acute treatment of migraine

Aim

The aim of this trial was to evaluate the efficacy and tolerability of ubrogepant (MK-1602), a calcitonin gene-related peptide receptor antagonist (CGRP-RA), for the acute treatment of migraine.

Methods

This double-blind, placebo-controlled study randomized 834 participants to treat one migraine attack with ubrogepant 1 mg, 10 mg, 25 mg, 50 mg, 100 mg, or placebo in a 1:1 ratio. The co-primary endpoints were pain freedom and headache response at two hours. The first primary hypothesis tested the dose-response trend for two-hour pain freedom using a logistic regression model. Subsequent hypotheses tested the effects of each dose on the co-primary endpoints, using a closed sequential testing procedure to control for multiplicity.

Results

A total of 527 participants received ubrogepant and 113 received placebo. A positive response trend in the proportion of participants achieving two-hour pain freedom was demonstrated ( p < 0.001). Ubrogepant 100 mg was significantly superior to placebo for two-hour pain freedom (25.5% vs 8.9%) but not for two-hour headache response. Per the prespecified multiplicity strategy, this nonsignificant result precluded further formal hypothesis testing, although the 50 mg and 25 mg doses demonstrated nominal significance over placebo for two-hour pain freedom (unadjusted p < 0.05). Overall, adverse events were similar between ubrogepant and placebo.

Conclusion

This trial supports ubrogepant’s efficacy and provides further evidence that CGRP-RAs are viable options for the acute treatment of migraine.

Safety and efficacy of AMG 334 for prevention of episodic migraine: a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

The calcitonin gene-related peptide (CGRP) pathway is a promising target for preventive therapies in patients with migraine. We assessed the safety and efficacy of AMG 334, a fully human monoclonal antibody against the CGRP receptor, for migraine prevention.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled, phase 2 trial, patients aged 18-60 years with 4 to 14 migraine days per month were enrolled at 59 headache and clinical research centres in North America and Europe, and randomly assigned in a 3:2:2:2 ratio to monthly subcutaneous placebo, AMG 334 7 mg, AMG 334 21 mg, or AMG 334 70 mg using a sponsor-generated randomisation sequence centrally executed by an interactive voice response or interactive web response system. Study site personnel, patients, and the sponsor study personnel were masked to the treatment assignment. The primary endpoint was the change in monthly migraine days from baseline to the last 4 weeks of the 12-week double-blind treatment phase. The primary endpoint was calculated using the least squares mean at each timepoint from a generalised linear mixed-effect model for repeated measures. Safety endpoints were adverse events, clinical laboratory values, vital signs, and anti-AMG 334 antibodies. The study is registered with ClinicalTrials.gov, number NCT01952574. An open-label extension phase of up to 256 weeks is ongoing and will assess the long-term safety of AMG 334.

FINDINGS

From Aug 6, 2013, to June 30, 2014, 483 patients were randomly assigned to placebo (n=160), AMG 334 7 mg (n=108), AMG 334 21 mg (n=108), or AMG 334 70 mg (n=107). The mean change in monthly migraine days at week 12 was -3·4 (SE 0·4) days with AMG 334 70 mg versus -2·3 (0·3) days with placebo (difference -1·1 days [95% CI -2·1 to -0·2], p=0·021). The mean reductions in monthly migraine days with the 7 mg (-2·2 [SE 0·4]) and the 21 mg (-2·4 [0·4]) doses were not significantly different from that with placebo. Adverse events were recorded in 82 (54%) patients who received placebo, 54 (50%) patients in the AMG 334 7 mg group, 54 (51%) patients in the AMG 334 21 mg group, and 57 (54%) patients in the AMG 334 70 mg group. The most frequently reported adverse events were nasopharyngitis, fatigue, and headache. Serious adverse events were reported for one patient in the AMG 334 7 mg group (ruptured ovarian cyst) and one patient in the AMG 334 70 mg group (migraine and vertigo); these events were judged to be unrelated to AMG 334 treatment. Nine (3%) of 317 patients had neutralising antibodies. No apparent association was recorded between patients with positive anti-AMG 334 antibodies and adverse events. No clinically significant vital signs, laboratory, or electrocardiogram findings were recorded.

INTERPRETATION

These results suggest that AMG 334 70 mg might be a potential therapy for migraine prevention in patients with episodic migraine and support further investigation of AMG 334 in larger phase 3 trials.

FUNDING

Amgen.

CGRP mechanism antagonists and migraine management

Migraine is a complex disorder of the brain that is common and highly disabling. As understanding of the neural pathways has advanced, and it has become clear that the vascular hypothesis does not explain the disorder, new therapeutic avenues have arisen. One such target is calcitonin gene-related peptide (CGRP)-based mechanisms. CGRP is found within the trigeminovascular nociceptive system widely from the trigeminal ganglion to second-order and third-order neurons and in regulatory areas in the brainstem. Studies have shown CGRP is released during severe migraine attacks and the reversal of the attack with effective triptan treatment normalizes those levels. CGRP administration triggers migraine in patients, and CGRP receptor antagonists have been shown to abort migraine. Here, we review the current state of CGRP mechanism antagonist therapy as its research and development is increasing in migraine therapeutics. We discuss several recent trials, highlighting the evidence base behind these novel drugs, and their potential future contribution to migraine management.

Safety, tolerability, and efficacy of TEV-48125 for preventive treatment of chronic migraine: a multicentre, randomised, double-blind, placebo-controlled, phase 2b study

BACKGROUND

Benefits of calcitonin-gene related peptide (CGRP) inhibition have not been established in chronic migraine. Here we assess the safety, tolerability, and efficacy of two doses of TEV-48125, a monoclonal anti-CGRP antibody, in the preventive treatment of chronic migraine.

METHODS

In this multicentre, randomised, double-blind, double-dummy, placebo-controlled, parallel-group phase 2b study, we enrolled men and women (aged 18-65 years) from 62 sites in the USA who had chronic migraine. Using a randomisation list generated by a central computerised system and an interactive web response system, we randomly assigned patients (1:1:1, stratified by sex and use of concomitant preventive drugs) to three 28-day treatment cycles of subcutaneous TEV-48125 675/225 mg (675 mg in the first treatment cycle and 225 mg in the second and third treatment cycles), TEV-48125 900 mg (900 mg in all three treatment cycles), or placebo. Investigators, patients, and the funder were blinded to treatment allocation. Daily headache information was captured using an electronic diary. Primary endpoints were change from baseline in the number of headache-hours during the third treatment cycle (weeks 9-12) and safety and tolerability during the study. Secondary endpoint was change in the number of moderate or severe headache-days in weeks 9-12 relative to baseline. Efficacy endpoints were analysed for the intention-to-treat population. Safety and tolerability were analysed using descriptive statistics. This trial is registered with ClinicalTrials.gov, number, NCT02021773.

FINDINGS

Between Jan 8, 2014, and Aug 27, 2014, we enrolled 264 participants: 89 were randomly assigned to receive placebo, 88 to receive 675/225 mg TEV-48125, and 87 to receive 900 mg TEV-48125. The mean change from baseline in number of headache-hours during weeks 9-12 was -59.84 h (SD 80.38) in the 675/225 mg group and -67.51 h (79.37) in the 900 mg group, compared with -37.10 h (79.44) in the placebo group. The least square mean difference in the reduction of headache-hours between the placebo and 675/225 mg dose groups was -22.74 h (95% CI -44.28 to -1.21; p=0.0386), whereas the difference between placebo and 900 mg dose groups was -30.41 h (-51.88 to -8.95; p=0.0057). Adverse events were reported by 36 (40%) patients in the placebo group, 47 (53%) patients in the 675/225 mg dose group, and 41 (47%) patients in the 900 mg dose group, whereas treatment-related adverse events were recorded in 15 (17%) patients, 25 (29%) patients, and 28 (32%) patients, respectively. The most common adverse events were mild injection-site pain and pruritus. Four (1%) patients had serious non-treatment-related adverse events (one patient in the placebo group, one patient in the 675/225 mg group, and two patients in the 900 mg group); no treatment-related adverse events were serious and there were no relevant changes in blood pressure or other vital signs.

INTERPRETATION

TEV-48125 given by subcutaneous injection every 28 days seems to be tolerable and effective, thus supporting the further development of TEV-48125 for the preventive treatment of chronic migraine in a phase 3 trial.

FUNDING

Teva Pharmaceuticals.

Therapeutic Monoclonal Antibodies: What Headache Specialists Need to Know

BACKGROUND

Monoclonal antibodies (mAbs) are now an important part of the treatment armamentarium for a wide range of conditions including cancer, autoimmune diseases, inflammatory diseases of the joint and bowel, transplant rejection, and multiple sclerosis. Significant progress over the last 30 years in the development of therapeutic mAbs has resulted in improved efficacy and safety. Monoclonal antibodies approved for the treatment of neurological illnesses so far are limited to use in multiple sclerosis. Several therapeutic mAbs have completed phase 2 clinical trials for migraine prevention, and there are phase 3 trials underway for migraine prophylaxis and for cluster headache at the time of this writing.

AIM

The purpose of this review is to discuss the characteristics of mAbs, including their mechanism of action and safety profile, and briefly describe the mAbs being evaluated for the prevention of migraine and cluster headaches.

SUMMARY

Monoclonal antibodies have several features that distinguish them from small molecules, including very high selectivity, relatively long half-life that generally allows for once or twice monthly dosing, and significantly reduced potential for drug-drug interactions or other nontarget related toxicities. The clinical development of mAbs that target calcitonin gene-related peptide and its receptor is underway and will evaluate this promising new drug class for the prevention of migraine and cluster headache.

Episodic and chronic migraine headache: breaking down barriers to optimal treatment and prevention

Migraine is a common disabling primary headache disorder that affects an estimated 36 million Americans. Migraine headaches often occur over many years or over an individual's lifetime. By definition, episodic migraine is characterized by headaches that occur on fewer than 15 days per month. According to the recent International Classification of Headache Disorders (third revision) beta diagnostic criteria, chronic migraine is defined as "headaches on at least 15 days per month for at least 3 months, with the features of migraine on at least 8 days per month." However, diagnostic criteria distinguishing episodic from chronic migraine continue to evolve. Persons with episodic migraine can remit, not change, or progress to high-frequency episodic or chronic migraine over time. Chronic migraine is associated with a substantially greater personal and societal burden, more frequent comorbidities, and possibly with persistent and progressive brain abnormalities. Many patients are poorly responsive to, or noncompliant with, conventional preventive therapies. The primary goals of migraine treatment include relieving pain, restoring function, and reducing headache frequency; an additional goal may be preventing progression to chronic migraine. Although all migraineurs require abortive treatment, and all patients with chronic migraine require preventive treatment, there are no definitive guidelines delineating which persons with episodic migraine would benefit from preventive therapy. Five US Food and Drug Association strategies are approved for preventing episodic migraine, but only injections with onabotulinumtoxinA are approved for preventing chronic migraine. Identifying persons who require migraine prophylaxis and selecting and initiating the most appropriate treatment strategy may prevent progression from episodic to chronic migraine and alleviate the pain and suffering associated with frequent migraine.

Taking the headache out of migraine

Migraine is a disease that contributes to major disability. Perhaps because migraine attacks are not immediately life-threatening per se and individuals return to a "normal" state between attacks, it is not taken seriously. However, migraine is associated with a number of comorbidities, including psychiatric disease, stroke, and other chronic pain disorders. Current acute treatments for episodic migraine are relatively effective, but preventive treatments for episodic and chronic migraine are far less so. Recent functional imaging studies have shown that the disease affects brain function and structure (either as a result of its genetic predisposition or as a result of repeated attacks). The current evidence in the pain field is that changes observed in brain function and structure may be reversible, adding credence to the notion that treating the disease aggressively and early may be beneficial to patients. Here we suggest a change in our approach to a disease that is currently not treated with the urgency that it deserves given its global prevalence, disease burden, and effects on brain function.

Localization of CGRP receptor components and receptor binding sites in rhesus monkey brainstem: A detailed study using in situ hybridization, immunofluorescence, and autoradiography

Functional imaging studies have revealed that certain brainstem areas are activated during migraine attacks. The neuropeptide calcitonin gene-related peptide (CGRP) is associated with activation of the trigeminovascular system and transmission of nociceptive information and plays a key role in migraine pathophysiology. Therefore, to elucidate the role of CGRP, it is critical to identify the regions within the brainstem that process CGRP signaling. In situ hybridization and immunofluorescence were performed to detect mRNA expression and define cellular localization of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1), respectively. To define CGRP receptor binding sites, in vitro autoradiography was performed with [(3)H]MK-3207 (a CGRP receptor antagonist). CLR and RAMP1 mRNA and protein expression were detected in the pineal gland, medial mammillary nucleus, median eminence, infundibular stem, periaqueductal gray, area postrema, pontine raphe nucleus, gracile nucleus, spinal trigeminal nucleus, and spinal cord. RAMP1 mRNA expression was also detected in the posterior hypothalamic area, trochlear nucleus, dorsal raphe nucleus, medial lemniscus, pontine nuclei, vagus nerve, inferior olive, abducens nucleus, and motor trigeminal nucleus; protein coexpression of CLR and RAMP1 was observed in these areas via immunofluorescence. [(3)H]MK-3207 showed high binding densities concordant with mRNA and protein expression. The present study suggests that several regions in the brainstem may be involved in CGRP signaling. Interestingly, we found receptor expression and antagonist binding in some areas that are not protected by the blood-brain barrier, which suggests that drugs inhibiting CGRP signaling may not be able to penetrate the central nervous system to antagonize receptors in these brain regions.

CGRP as a neuropeptide in migraine: lessons from mice

Migraine is a neurological disorder that is far more than just a bad headache. A hallmark of migraine is altered sensory perception. A likely contributor to this altered perception is the neuropeptide calcitonin gene-related peptide (CGRP). Over the past decade, CGRP has become firmly established as a key player in migraine. Although the mechanisms and sites of action by which CGRP might trigger migraine remain speculative, recent advances with mouse models provide some hints. This brief review focuses on how CGRP might act as both a central and peripheral neuromodulator to contribute to the migraine-like symptom of light aversive behaviour in mice.

Review of dose-response curves for acute antimigraine drugs: triptans, 5-HT1F agonists and CGRP antagonists

INTRODUCTION

Dose-response curves for efficacy and tolerability are the important determinants for the choice of doses of acute migraine drugs.

AREAS COVERED

Dose-response curves for the efficacy of seven triptans (5-HT1B/1D receptor agonists), a 5-HT1F receptor agonist (lasmiditan) and four oral calcitonin-gene related peptide receptor antagonists (telcagepant, MK-3207, BI 44370 TA and BMS-927711) in placebo-controlled trials were reviewed. In addition, dose-response curves for adverse events (AEs) were reviewed.

EXPERT OPINION

For most triptans, the dose-response curve for efficacy is flat, whereas AEs often increase with increasing doses. The two other groups of drugs also have flat dose-response curves for efficacy. Overall, the triptans still have the most favorable efficacy-tolerability profile. Current acute antimigraine drugs do not fulfill the expectations of the patients, and thus, there are many unmet needs. Although upcoming drugs may not be superior to triptans, migraine patients will potentially benefit greatly from these, especially patients who are triptan non-responders and patients with cardiovascular disease.

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.

Practical implications of the migraine cardio- and cerebrovascular association: unmet needs of patients

BACKGROUND

Numerous studies have described a relationship between migraine and stroke, and there is emerging evidence that migraine is also associated with cardiovascular disease. The combination of migraine and both cerebrovascular and cardiovascular disease has implications for therapy.

METHODS

We conducted a review of the modifications in medical therapy in patients with comorbid migraine and cardio- and cerebrovascular disorders based on publications from the last 15 years.

RESULTS

Some drugs are contraindicated to treat migraine attacks (ergots, triptans) or for migraine prevention in patients after transient ischemic attack (TIA)/ischemic stroke. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) are contraindicated in patients with cerebral bleeding. Some drugs for the treatment of acute migraine attacks are contraindicated in patients with symptomatic coronary heart disease.

CONCLUSIONS

Given the large number of patients with comorbid migraine and cardiovascular as well as cerebrovascular disease, there is an unmet need to treat these patients.

New treatments for headache

Migraine and cluster headache are primary headache disorders commonly encountered in clinical practice. Despite the profound disability caused by these primary headache disorders, available acute and preventive treatment options are limited. Recent understanding of headache pathophysiology has led to the development of new drug formulations and novel drug targets that are extremely promising. This article will highlight several of the new treatments that are currently under investigation including novel delivery mechanisms of already existing medications, calcitonin gene-related peptide (CGRP) receptor antagonists, antibodies to CGRP and its receptor, serotonin receptor agonists, transient receptor potential vanilloid receptor modulators, orexin receptor antagonists, glial cell modulators, and neuromodulation. If data is supportive, these therapies will be welcome additions to the headache specialist's armamentarium.

Novel strategies for the treatment of migraine attacks via the CGRP, serotonin, dopamine, PAC1, and NMDA receptors

INTRODUCTION

Migraine is a common, paroxysmal, and disabling primary headache with a high personal and socioeconomic impact. It involves ∼ 16% of the general population. During the years, a number of hypotheses have been put forward concerning the exact pathomechanism, but the final solution is still undiscovered.

AREAS COVERED

Although the origin is enigmatic, parallel therapeutic efforts have been developed. Current attack therapy does not meet the expectations of the patients or the doctors. This article, based on a PubMed search, reviews the novel pharmacological possibilities that influence the peripheral and central sensitization involved in the disease.

EXPERT OPINION

In order to overcome the therapeutic insufficiency, a calcitonin gene-related peptide receptor antagonist without the side-effect of liver transaminase elevation is required. Another therapeutic option is to develop a neurally acting antimigraine agent, such as a serotonin-1F receptor agonist, with low adverse central nervous system events. Development of a potent dopamine receptor antagonist is necessary to diminish the premonitory symptoms of migraine. A further option is to decrease the headache intensity with a pituitary adenylate cyclase-activating polypeptide type 1 receptor blocker which can cross the blood-brain barrier. Finally, synthetic kynurenine analogues are required to block the pain transmission in the activated trigeminal system.

Calcitonin gene-related peptide (CGRP): a new target for migraine

Migraine is a neurological disorder that manifests as a debilitating headache associated with altered sensory perception. The neuropeptide calcitonin gene-related peptide (CGRP) is now firmly established as a key player in migraine. Clinical trials carried out during the past decade have proved that CGRP receptor antagonists are effective for treating migraine, and antibodies to the receptor and CGRP are currently under investigation. Despite this progress in the clinical arena, the mechanisms by which CGRP triggers migraine remain uncertain. This review discusses mechanisms whereby CGRP enhances sensitivity to sensory input at multiple levels in both the periphery and central nervous system. Future studies on epistatic and epigenetic regulators of CGRP actions are expected to shed further light on CGRP actions in migraine. In conclusion, targeting CGRP represents an approachable therapeutic strategy for migraine.

Calcitonin gene-related peptide: physiology and pathophysiology

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.

New targets for migraine therapy

OPINION STATEMENT

The shift in our understanding of migraine as a vascular disorder to a brain disorder has opened new avenues for the development of novel therapeutics with neural targets. The advent of 5-HT1B/1D receptor agonists, the triptans, in the 1990s was a crucial step in the modern evolution of treatment. The use of triptans, like their predecessors, is limited by their vasoconstrictor effects, and new development has been slowed by poor academic research funding to identify new targets. The development of agents without vascular effects, such as calcitonin gene-related peptide receptor antagonists and selective serotonin 5-HT1F receptor agonists, will bring more effective treatments to a population currently without migraine-specific options. In addition, advances in understanding migraine pathophysiology have identified new potential pharmacologic targets such as acid-sensing ion channels, glutamate and orexin receptors, nitric oxide synthase (NOS), and transient receptor potential (TRP) channels. Although previous attempts to block subtypes of glutamate receptors, NOS, and TRP channels have had mixed outcomes, new molecules for the same targets are currently under investigation. Finally, an entirely new approach to migraine treatment with noninvasive neuromodulation via transcutaneous neurostimulation or transcranial magnetic stimulation is just beginning. Hopefully in the coming years we will see a new era of migraine therapy, with multiple classes of better-tolerated, more effective agents targeting diverse yet specific migraine mechanisms.

Monoclonal antibodies for migraine: preventing calcitonin gene-related peptide activity

Calcitonin gene-related peptide (CGRP) is a well-studied neuropeptide of relevance for migraine pathophysiology. Jugular levels of CGRP are increased during migraine attacks, and intravenous CGRP administration induces migraine-like headache in most individuals with migraine. Several CGRP receptor antagonists (CGRP-RAs) were shown to be effective for the acute treatment of migraine, validating the target for the treatment of migraine. However, for a number of reasons, including issues of liver toxicity with chronic use, the development of CGRP-RAs has yet to produce a viable clinical therapeutic. Development of monoclonal antibodies (mAbs) targeting the CGRP pathway is an alternative approach that should avoid many of the issues seen with CGRP-RAs. The exquisite target specificity, prolonged half-lives, and reduced potential for hepatotoxicity and drug-drug interactions make mAbs suitable for the preventive treatment of migraine headaches. This manuscript provides an overview of the role of CGRP in the pathophysiology of migraine, followed by a review of the clinical development of CGRP-RAs. Some basic concepts on antibodies are then discussed along with the publicly disclosed information on the development of mAbs targeting the CGRP pathway.

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.

Mast cells: versatile gatekeepers of pain

Mast cells are important first responders in protective pain responses that provoke withdrawal from intense, noxious environmental stimuli, in part because of their sentinel location in tissue-environment interfaces. In chronic pain disorders, the proximity of mast cells to nerves potentiates critical molecular cross-talk between these two cell types that results in their synergistic contribution to the initiation and propagation of long-term changes in pain responses via intricate signal networks of neurotransmitters, cytokines and adhesion molecules. Both in rodent models of inflammatory pain and chronic pain disorders, as well as in increasing evidence from the clinic, it is abundantly clear that understanding the mast cell-mediated mechanisms underlying protective and maladaptive pain cascades will lead to improved understanding of mast cell biology as well as the development of novel, targeted therapies for the treatment and management of debilitating pain conditions.