Translational Pharmacodynamics of Calcitonin Gene-Related Peptide Monoclonal Antibody LY2951742 in a Capsaicin-Induced Dermal Blood Flow Model

IUPHAR review: Navigating the role of preclinical models in pain research

Chronic pain is a complex and challenging medical condition that affects millions of people worldwide. Understanding the underlying mechanisms of chronic pain is a key goal of preclinical pain research so that more effective treatment strategies can be developed. In this review, we explore nociception, pain, and the multifaceted factors that lead to chronic pain by focusing on preclinical models. We provide a detailed look into inflammatory and neuropathic pain models and discuss the most used animal models for studying the mechanisms behind these conditions. Additionally, we emphasize the vital role of these preclinical models in developing new pain-relief drugs, focusing on biologics and the therapeutic potential of NMDA and cannabinoid receptor antagonists. We also discuss the challenges of TRPV1 modulation for pain treatment, the clinical failures of neurokinin (NK)- 1 receptor antagonists, and the partial success story of Ziconotide to provide valuable lessons for preclinical pain models. Finally, we highlight the overall success and limitations of current treatments for chronic pain while providing critical insights into the development of more effective therapies to alleviate the burden of chronic pain.

Baseline demographics and disease characteristics of patients with episodic or chronic cluster headache: data from two phase 3 randomized clinical trials in Europe and North America

Objective

Two phase 3 galcanezumab trials were conducted in Europe and North America to analyze the reduction of weekly cluster headache (CH) attack frequency in populations with episodic and chronic CH. The current study aims to illustrate prospectively recorded baseline clinical data from these trials and to identify possible predictors of response.

Methods

Patients (aged 18-65 years) met The International Classification of Headache Disorders 3rd edition-beta criteria for CH. Attacks were evaluated using an electronic headache diary for 7-day (episodic) or 14-day (chronic) eligibility assessments before patients were randomized 1:1 to monthly subcutaneous galcanezumab 300 mg or placebo.

Results

Data were collected from 106 patients with episodic and 237 with chronic CH. Overall, the mean age [standard deviation] was 45.4 [11.0] years; patients were predominantly White (84.5%), male (75.8%), and European (77.6%). Patients with episodic CH reported 17.5 [10.0] attacks/week; patients with chronic CH reported 18.8 [10.2] attacks/week. The average pain severity score (range 0-4) was 2.5 [0.7] for episodic CH and 2.7 [0.7] for chronic CH. Higher attack frequency was a possible predictor of response to galcanezumab; potential negative predictors of response were greater attack severity and duration.

Conclusion

This large dataset of patients with CH provides reliable systematically and prospectively collected information on disease characteristics. The analysis in episodic CH underscores potential predictors of response worth considering for future CH trial design.

Clinical Trial Registration

ClinicalTrials.gov, identifiers: NCT02397473 and NCT02438826.

Revisiting Migraine: The Evolving Pathophysiology and the Expanding Management Armamentarium

Migraine affects about one billion people worldwide yearly and is one of the most common neurologic illnesses, with a high prevalence and morbidity, particularly among young adults and females. Migraine is associated with many comorbidities, including stress, sleep difficulties, and suicidal ideation. Migraine, despite its widespread occurrence, is underdiagnosed and undertreated. Because of the complicated and primarily unknown mechanisms of migraine formation, several social and biological risk factors, such as hormone imbalances, genetic and epigenetic impacts, and cardiovascular, neurological, and autoimmune illnesses, have been proposed. Through the mid-20th century diversion of the now-defunct vascular theory, the pathophysiology of migraine has developed from a historical study of the "humours" to a distinct entity as a neurological disorder. The range of therapeutic targets has broadened significantly, increasing the number of specialized clinical trials. Understanding the biology of migraine through careful research has resulted in the identification of major therapeutic classes: (i) triptans, serotonin 5-HT1B/1D receptor agonists, (ii) gepants, calcitonin gene-related peptide (CGRP) receptor antagonists, (iii) ditans, 5-HT1F receptor agonists, (iv) CGRP monoclonal antibodies, and (v) glurants, mGlu5 modulators, with further targets being explored. This review provides a comprehensive overview of the most recent literature on epidemiology and risk factors and exposes knowledge gaps.

Galcanezumab modulates Capsaicin-induced C-fiber reactivity

Background

The vasodilatory calcitonin-gene related peptide (CGRP) is understood as pivotal mediator in migraine pathophysiology. Blocking CGRP with small molecules or monoclonal antibodies (CGRP-mAb) reduces migraine frequency. However, prescription of CGRP-mAbs is still regulated and possible predictive measures of therapeutic success would be useful.

Methods

Using standardized capsaicin-induced dermal blood flow model, 29 migraine patients underwent a laser speckle imaging measurement before and after administration of galcanezumab. At both sessions dermal blood flow before and after capsaicin stimulation as well as flare size were analyzed over all three trigeminal branches and the volar forearm for extracranial control. Long-term measures were repeated in 14 patients after continuous treatment ranging from 6 to 12 months.

Results

Resting dermal blood flow remained unchanged after administration of galcanezumab. Capsaicin-induced dermal blood flow decreased significantly after CGRP-mAb in all tested areas compared to baseline and this was consistent even after 12 months of treatment. However, following galcanezumab administration, the flare size decreased only in the three trigeminal dermatomes, not the arm and was therefore specific for the trigemino-vascular system. None of these two markers distinguished between responders and non-responders.

Conclusion

CGRP-mAb changed blood flow response to capsaicin stimulation profoundly and this effect did not change over a 12-month application. Neither capsaicin-induced flare nor dermal blood flow can be used as a predictor for treatment efficacy. These data suggest that the mechanism of headache development in migraine is not entirely CGRP-mediated.

Real-world efficacy of galcanezumab for the treatment of migraine in Korean patients

BACKGROUND AND OBJECTIVE

We aimed to provide real-world data on the effectiveness of an anti-calcitonin gene-related peptide monoclonal antibody administered for treating migraine in Korean patients.

METHODS

We prospectively recruited patients with migraine who received galcanezumab treatment at a single university hospital from June 2020 to April 2021. The treatment response was assessed after three consecutive monthly injections. A 50% responder rate was evaluated based on ≥50% reduction in the number of moderate/severe headache days.

RESULTS

Overall, 87 patients were included in the analysis. Most patients were women (83.9%). They had a mean age of 41.7 ± 12.3 years (range 17-72). Sixty-five patients (74.7%) had chronic migraine, 35 patients (40.2%) had a history of medication-overuse headache, and 32 patients (36.8%) were previously unresponsive to or found intolerable five classes of preventive medication. After three months of treatment, mean changes in numbers of monthly headache days, moderate/severe headache days, crystal clear days, and days of acute medication use were -7.2 ± 8.43, -4.3 ± 9.76, 7.3 ± 8.50, and -4.1 ± 7.93, respectively. The 50% responder rates were 58.3%, 44.2%, and 40.6% for patients with unsuccessful previous use of 0-1, 2-4, and 5 preventive medication classes, respectively. Headache Impact Test-6 and Migraine Disability Assessment Test scores also decreased (-4.4 ± 8.09 and -32.9 ± 77.04, respectively).

CONCLUSION

In our cohort, the effectiveness and safety of galcanezumab were comparable with those reported in clinical trials, whereas a higher response rate was observed in the difficult-to-treat patient subset than that reported in trials. We provide real-world evidence of galcanezumab treatment benefits in Asian patients with migraine.

Optimization of capsaicin-induced dermal blood flow measurement by laser Doppler imaging in cynomolgus macaque

BACKGROUND

Capsaicin is used in several areas of non-human primate research including allodynia and dermal blood flow (DBF). The capsaicin-induced DBF increase was measured using laser Doppler imaging (LDI), but this response is known to diminish upon repeated topical applications. Refinement of the experimental procedures could improve the rigor and reproducibility of the DBF migraine model.

METHODS

Optimal anatomical site in cynomolgus was determined, and conditions and experimental settings for DBF measurement using LDI were established. Then, two study design trial structures were compared.

RESULTS

Medial thigh was the preferrable site, and an ethanol-Tween 20 formulation of capsaicin was desirable. A 1-week washout for contralateral side or 2-week washout for ipsilateral side was necessary to eradicate capsaicin desensitization.

CONCLUSIONS

With the established technicality in DBF measurements in cynomolgus macaques, the capsaicin-induced DBF model may be utilized in translational medical research in developing migraine therapeutics.

Monoclonal Antibodies Targeting CGRP: From Clinical Studies to Real-World Evidence-What Do We Know So Far?

Now more than ever is the time of monoclonal antibody use in neurology. In headaches, disease-specific and mechanism-based treatments existed only for symptomatic management of migraines (i.e., triptans), while the standard prophylactic anti-migraine treatments consist of non-specific and repurposed drugs that share limited safety profiles and high risk for interactions with other medications, resulting in rundown adherence rates. Recent advances in headache science have increased our understanding of the role of calcitonin gene relate peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) pathways in cephalic pain neurotransmission and peripheral or central sensitization, leading to the development of monoclonal antibodies (mAbs) or small molecules targeting these neuropeptides or their receptors. Large scale randomized clinical trials confirmed that inhibition of the CGRP system attenuates migraine, while the PACAP mediated nociception is still under scientific and clinical investigation. In this review, we provide the latest clinical evidence for the use of anti-CGRP in migraine prevention with emphasis on efficacy and safety outcomes from Phase III and real-world studies.

Current advances in the management of cluster headaches

Introduction: Cluster headache (CH) is probably the most severe idiopathic pain condition, yet its current medical management remains poor.Areas covered: Only repurpose medicines are currently in use for the prevention of CH, partially because the pathophysiology of the condition is still elusive. In this article we performed a systematic review to evaluate the evidence for efficacy of the currently available or emerging treatments for CH.Expert opinion: We found several ongoing randomized clinical trials testing prophylactic treatments for CH and only few for the standard ones. Recent data from randomized trials with monoclonal antibodies targeting the calcitonin gene related peptide pathway (anti-CGRP mAbs) are controversial, although its role in the pathogenesis of the condition is well documented. This inconsistency may depict inadequacies in clinical trial designing. Anti-CGRP mAbs and antagonists of pituitary adenylate cyclase-activating polypeptide (PACAP) along with neuromodulation techniques, are curing the necessary valuable evidence that could illuminate the therapeutical future for cluster headache. Orexin pathway is another attractive target for CH treatment. To improve the evidence for efficacy, we further propose that the design of the clinical trials for CH needs to be radically reviewed to allow more patients to participate.

Relationship of the Calcitonin Gene-Related Peptide Monoclonal Antibody Galcanezumab Pharmacokinetics and Capsaicin-Induced Dermal Blood Flow in Healthy Subjects

Galcanezumab, a humanized monoclonal antibody targeting calcitonin gene-related peptide, was recently approved for migraine prophylaxis. The pharmacokinetic/pharmacodynamic (PK/PD) relationship between galcanezumab concentration and inhibition of capsaicin-induced dermal blood flow (CIDBF) was evaluated using first-in-human data following 6 single subcutaneous doses (1 to 600 mg) or multiple (4) 150-mg doses every 2 weeks in 7 cohorts (7 actively treated subjects and 2 placebo-treated healthy subjects). Galcanezumab pharmacokinetics were best described by a 1-compartment model with delayed first-order absorption/linear elimination. Apparent estimates (between-subject variability) of clearance, volume of distribution, absorption rate constant, and lag time were 0.0106 L/h (27%CV), 11.2 L (21%CV), 0.0192 h^-1 (89%CV), and 0.202 hours, respectively. Estimated elimination half-life was about 30 days. An effect compartment link model described the concentration-effect relationship; estimated maximum inhibitory effect was 70.5%, and 50% maximum inhibitory effect concentration (IC₅₀ ) was 1060 ng/mL. Galcanezumab showed dose- and concentration-dependent potent and durable inhibition of CIDBF. Simulated effect compartment concentrations were maintained above IC₅₀ after 12 weeks of dosing. Near-maximal CIDBF inhibition occurred with 150 mg biweekly for 12 weeks lasting ≥24 weeks or with ≥30 mg every 2 weeks or 195 mg every 13 weeks. Quantitative modeling of galcanezumab PK/PD supported dose selection for the phase 2 proof-of-concept study.

The Role of Galcanezumab in Migraine Prevention: Existing Data and Future Directions

Galcanezumab is a humanized monoclonal antibody blocking the calcitonin gene-related peptide (CGRP) pathway by targeting the CGRP. Data from four phase-3 randomized placebo-controlled clinical trials showed that galcanezumab is superior to placebo in reducing migraine headaches, migraine-specific quality of life, and headache-related disability. Most of the adverse events (AEs) were mild to moderate and did not affect trial completion rates significantly. Along with erenumab, fremanezumab, and eptinezumab, galcanezumab forms a novel class of anti-migraine preventative treatments that is disease-specific and mechanism-based, unlike the standard ones. In addition, galcanezumab has also been shown to be effective in cluster headache, though more clinical trials are required. Overall, galcanezumab is a promising emerging treatment in migraine prophylaxis. However, it needs to be tested in larger clinical trials focused on treatment-resistant migraine. Furthermore, its safety profile, especially its potential association with an increased cardiovascular risk, needs to be established through long-term, real-world data. This review aims to give an overview of its pharmacological properties as well as to report and discuss data from clinical trials and its potential place in headache therapeutics.

Galcanezumab: A Review in the Prevention of Migraine and Treatment of Episodic Cluster Headache

Galcanezumab (Emgality^®) is a humanized monoclonal antibody targeting the calcitonin gene-related peptide (CGRP), thereby inhibiting its physiological activity, with CGRP playing a key role in the pathophysiology of migraine and headache disorders. In pivotal phase 3 trials, recommended dosages of subcutaneous galcanezumab once monthly were significantly more effective than placebo as preventive therapy in adults with episodic (EVOLVE-1 and -2; over 6 months) or chronic (REGAIN; over 3 months) migraine (±  aura), including in patients who had failed several prior preventive migraine drugs (CONQUER; over 3 months). The beneficial effects of galcanezumab preventive treatment in reducing the number of monthly migraine headache days (MHDs) and improving health-related quality of life (HR-QOL) were sustained during up to 1 year of treatment. In adults with episodic cluster headache, galcanezumab treatment was associated with a significant reduction in the weekly frequency of cluster headache attacks across weeks 1-3 compared with placebo (primary endpoint), albeit during weeks 4-8, there was a convergence of results between these treatment groups. Although further evidence from the clinical setting is required to determine its long-term safety profile, given its convenient administration regimen, efficacy and short-term tolerability profile, monthly galcanezumab represents an important emerging option for the prevention of episodic and chronic migraine (±  aura) and the treatment of episodic cluster headache.

Galcanezumab for the prevention of migraine

Migraine is a common and disabling disorder affecting approximately 1.02 billion people worldwide. Calcitonin gene-related peptide (CGRP) has been identified as playing an important role in the pathophysiology of migraine and several migraine-specific therapies targeting the CGRP ligand or its receptor have been approved since 2018 for the acute and preventive treatment of migraine. This review focuses on the pharmacology, clinical efficacy and safety/tolerability of galcanezumab, an anti-CGRP monoclonal antibody approved for the prevention of migraine.

Drug profile: galcanezumab for prevention of cluster headache

Introduction: Cluster headache [CH] is a severely disabling trigeminal autonomic cephalalgia [TAC]. Approximately 1 in 1,000 adults are affected by CH. Calcitonin gene-related peptide [CGRP] is an important mediator in the pathophysiology of CH. Galcanezumab is a monoclonal antibody with an affinity for the CGRP peptide, FDA approved for the prevention of episodic CH. Areas covered: Search words queried were 'cluster headache,' 'cluster headache, and CGRP,' 'cluster headache, and galcanezumab.' Over 99 articles in Pubmed and prescribing information for galcanezumab were reviewed. Some of the data pertaining to CH trials with fremanezumab were reviewed using clinical trials.org. Expert opinion: Galcanezumab has shown benefit in decreasing the weekly frequency of CH attacks across week 1 through week 3 in patients with CH; 8.7 attacks in the galcanezumab group, as compared with 5.2 in the placebo group (95% confidence interval, 0.2 to 6.7; P = 0.04). It has a favorable risk-benefit ratio. The prevention of CH with CGRP inhibition represents a novel advance for a condition with a significant unmet need. The negative trial results of galcanezumab for chronic cluster headache [CCH] may be due to the refractory nature and sheds light on the critical need to investigate the underlying biology and therapeutic options.

An Evidence-Based Review of Galcanezumab for the Treatment of Migraine

PURPOSE OF REVIEW

This is a comprehensive review of the current literature on the usage of galcanezumab for migraine treatment. It reviews the biology, pathophysiology, epidemiology, diagnosis, and conventional treatment of migraines, then compares the literature available for galcanezumab with historical treatment options.

RECENT FINDINGS

Migraine is a common headache disorder and constitutes a significant source of distress from both a personal and societal perspective. Conventional treatment includes abortive and preventive treatment. Treatment options are limited and may be only partially or minimally effective in some of the population. Recent evidence points to metabolic changes in the brain as possible causes of migraine, via reduced available energy or a spiking need for it, resulting in a relative insufficiency. This leads to trigeminocervical complex (TCC) activation and a headache episode, modulated by calcitonin gene-related peptide (CGRP). Galcanezumab (Emgality) is a monoclonal antibody targeting CGRP that is given in a monthly injection for the prevention of migraines. Its safety was previously shown in phase 1 and 2 trials, and recent phase 3 trials showed efficacy, with up to 50% reduction in monthly migraine days and improved functional capacity in migraineurs. Studies show that the drug is well tolerated and safe. Migraine headache is a common neurological syndrome that causes great pain and suffering. Treatment options today are limited. Galcanezumab does not prevent migraines, but it is effective in decreasing their frequency and length. It is also much better tolerated than the currently existing therapies. While it is unlikely to provide monotherapy for migraines, it is a novel therapy that may be added for cases of severe or frequent migraines.

Efficacy of Galcanezumab for Migraine Prevention in Patients With a Medical History of Anxiety and/or Depression: A Post Hoc Analysis of the Phase 3, Randomized, Double-Blind, Placebo-Controlled REGAIN, and Pooled EVOLVE-1 and EVOLVE-2 Studies

OBJECTIVE

This post hoc analysis evaluated the efficacy of galcanezumab for the prevention of migraine in patients with and without comorbid anxiety and/or depression.

BACKGROUND

Patients with migraine have a higher risk of anxiety and/or depression. Given the high prevalence of psychiatric symptoms and their potential negative prognostic impact, determining the efficacy of migraine treatments in patients with these comorbidities is important.

METHODS

The results of 2 phase 3 episodic migraine studies of patients with 4-14 migraine headache days (MHD) per month were pooled. A third chronic migraine study, which was evaluated separately, enrolled patients with ≥15 headache days per month, of which ≥8 had migraine-like features. Patients in all 3 studies were randomized 2:1:1 to placebo, galcanezumab 120 mg, or galcanezumab 240 mg. The efficacy of galcanezumab on migraine was measured in subgroups of patients with anxiety and/or depression (current or past) and patients without. A repeated measures model was used to compare treatment groups within each subgroup and to test for consistency of treatment effect across the anxiety/depression subgroups (subgroup-by-treatment interaction) during the double-blind treatment phases.

RESULTS

Among 1773 intent-to-treat patients with episodic migraine, both doses of galcanezumab demonstrated statistically significant improvements relative to placebo in overall number of MHD for the subgroups of patients with anxiety and/or depression (mean change difference from placebo [95% CI]: -2.07 [-2.81, -1.33] for galcanezumab 120 mg [P < .001], -1.91 [-2.78, -1.04] for 240 mg [P < .001]) and without anxiety and/or depression (mean change difference from placebo [95% CI]: -1.92 [-2.36, -1.47] for 120 mg [P < .001], -1.77 [-2.20, -1.33] for 240 mg [P < .001]), as was observed for the secondary outcomes of MHD with acute medication use and functional impairment. Among 1113 intent-to-treat patients with chronic migraine, those with anxiety and/or depression had significant reductions in overall MHD frequency with the 240-mg dose (mean change difference from placebo [95% CI]: -1.92 [-3.52, -0.33]; P = .018), whereas significant reductions were observed at both the 120-mg (mean change difference from placebo [95% CI]: -2.29 [-3.26, -1.31]; P < .001) and 240-mg (-1.85 [-2.83, -0.87]; P < .001) doses in patients without anxiety and/or depressions. Significant reductions (P < .01) in MHD with acute medication use were observed at both doses within both anxiety/depression subgroups and for overall functional impairment for patients without anxiety and/or depression, though neither dose significantly reduced overall functional impairment beyond placebo in the subgroup with anxiety and/or depression. In the episodic and chronic migraine studies, the subgroup-by-treatment interaction was not statistically significant for MHD, MHD with acute medication use, or functional impairment (chronic study only), suggesting a lack of evidence of differential effect between subgroups. Furthermore, differences between subgroups in the mean change differences from placebo, as well as overlapping 95% confidence intervals for the subgroups, indicated lack of a clinical or statistical difference between subgroups for these outcome variables. There was a significantly higher percentage of patients with episodic migraine attaining ≥50%, ≥75%, and 100% reductions, and a higher percentage of patients with chronic migraine attaining ≥50% and ≥75% reductions from baseline with galcanezumab compared with placebo, regardless of medical history of anxiety and/or depression.

CONCLUSIONS

A medical history of anxiety and/or depression does not seem to interfere with response to galcanezumab among patients with episodic migraine, and both doses of galcanezumab appear efficacious for these individuals regardless of this psychiatric history. Among patients with chronic migraine and comorbid anxiety and/or depression, the 240-mg dose, but not the 120-mg dose, significantly decreased overall MHD, but neither dose resulted in significantly greater functional improvement. Patients with migraine and comorbid anxiety and/or depression often require additional interventions, and this may be more important in chronic migraine.

Safety, tolerability, and efficacy of orally administered atogepant for the prevention of episodic migraine in adults: a double-blind, randomised phase 2b/3 trial

BACKGROUND

Atogepant is an orally administered, small-molecule, calcitonin gene-related peptide (CGRP) receptor antagonist under investigation for treatment of migraine. We aimed to examine a range of oral doses for safety, tolerability, and efficacy for the preventive treatment of migraine.

METHODS

In this double-blind, phase 2b/3 trial, adults (aged 18-75 years), with a history (≥1 year) of migraine and 4-14 migraine days per month, were randomly assigned 2:1:2:2:1:1 (by means of a sequence generated by the statistical programming department of the sponsor, and operationalised through an automated interactive web-based response system) to receive placebo or atogepant 10 mg once daily, 30 mg once daily, 60 mg once daily, 30 mg twice daily, or 60 mg twice daily, in matching capsules. Participants, site personnel, and all study sponsor personnel were masked to treatment allocations. The study was done in 78 academic and private practice settings in the USA. The primary outcome was change from baseline in monthly migraine days across 12 weeks of treatment using a modified intention-to-treat approach. The overall type I error rate for multiple comparisons across active treatment doses was controlled at the 0·05 level by means of a graphic approach. The main outcomes to assess safety and tolerability were adverse event recordings. The trial is registered with ClinicalTrials.gov, NCT02848326 and is completed.

FINDINGS

Between Sept 6, 2016, and April 23, 2018, of 1772 individuals screened, 834 were randomly assigned and 825 received one dose or more of study medication: 186 received placebo, 93 atogepant 10 mg once daily, 183 atogepant 30 mg once daily, 186 atogepant 60 mg once daily, 86 atogepant 30 mg twice daily, and 91 atogepant 60 mg twice daily. Overall, 714 (87%) of 825 participants were female, 628 (76%) were white, median migraine duration was 17·5 years (IQR 10·0-28·0), and 232 (28%) had previously used preventive treatment. The primary efficacy analysis included 795 patients: 178 received placebo, 92 atogepant 10 mg once daily, 182 atogepant 30 mg once daily, 177 atogepant 60 mg once daily, 79 atogepant 30 mg twice daily, and 87 atogepant 60 mg twice daily. Across the 12-week treatment period, all five atogepant groups showed significant least-squares mean (SE) change from baseline in mean monthly migraine days versus placebo: atogepant 10 mg once daily -4·0 (0·3; p=0·024), 30 mg once daily -3·8 (0·2; p=0·039), 60 mg once daily -3·6 (0·2; p=0·039), 30 mg twice daily -4·2 (0·4; p=0·0034), and 60 mg twice daily -4·1 (0·3; p=0·0031); placebo -2·9 (0·2). The most common treatment-emergent adverse events (TEAEs) across all groups were nausea (range 5% [5/93] for 10 mg once daily to 12% [22/186] for 60 mg once daily vs 5% [9/186] for placebo) and fatigue (1% [1/93] for 10 mg once daily to 10% [9/91] for 60 mg twice daily vs 3% [6/186] for placebo). Treatment-related TEAE frequency ranged from 18% (17/93) for 10 mg once daily to 26% (24/91) for 60 mg twice daily, versus 16% (30/186) for placebo. Seven participants reported a total of eight serious TEAEs (two participants each in the placebo, 30 mg once-daily, and 60 mg once-daily groups, and one participant in the 10 mg once-daily group). TEAEs leading to discontinuation were reported in 33 (5%) of 639 atogepant participants and 5 (3%) of 186 of those randomised to placebo. All serious TEAEs were unrelated to treatment.

INTERPRETATION

All doses of oral atogepant were associated with a significant decrease in monthly migraine days over 12 weeks compared with placebo. Atogepant was safe and well tolerated over 12 weeks, supporting its phase 3 development for the preventive treatment of migraine.

FUNDING

Allergan (before its acquisition by AbbVie).

Galcanezumab for the prevention of cluster headache

INTRODUCTION

Cluster headache (CH) is among the worst painful conditions. The available therapies are scarce and not specific, leaving many patients unsatisfied because of poor efficacy and/or tolerability. Patients not responding to common treatments are offered semi-invasive and invasive procedures with uncertain results. Based on the current understanding of CH pathophysiology, new possible therapeutic approaches come from drugs interfering with Calcitonin Gene Related Peptide (CGRP).

AREAS COVERED

After summarizing the evidence for CGRP involvement in CH pathophysiology, we review the published literature (PubMed) and information (clinicaltrials.gov, EudraCT, EMA and FDA websites) regarding a novel anti-CGRP monoclonal antibody, Galcanezumab, its pharmacological properties, development, and evidence for the treatment of CH. Publications regarding other indications (migraine) are considered for completeness and safety/tolerability profile.

EXPERT OPINION

In one randomized clinical trial, Galcanezumab has proven to be effective and safe as a preventive treatment in episodic CH, with a favorable tolerability profile offering a potential new option in the therapeutic arsenal. Inefficacy of galcanezumab in chronic CH as well as the inefficacy of another monoclonal antibody against CGRP (fremanezumab) in both episodic and chronic CH question the scalability of the drug in CH management. Further, studies comparing galcanezumab to the current standard treatments are highly desirable.

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.

Once-monthly galcanezumab for the prevention of migraine in adults: an evidence-based descriptive review and potential place in therapy

In the last 15 years relevant efforts have been made to demonstrate that calcitonin gene-related peptide (CGRP) antagonism is a valuable and druggable mechanism for treatment or prevention of migraine. Galcanezumab is one of the antibodies developed and studied to prevent migraine by targeting CGRP. The scope of this review is to report data currently available on galcanezumab. According to available data, galcanezumab is safe and efficacious in preventing migraine in episodic migraine patients, also reducing disability and functional impairment due to the disorder. In September 2018, galcanezumab was approved in the USA for the prevention of migraine in adults. The placement of galcanezumab into the current therapeutic scenario will be a revolution for migraine patients, and probably in a less near future also for patients affected by other primary headaches.

Dural Calcitonin Gene-Related Peptide Produces Female-Specific Responses in Rodent Migraine Models

Migraine is the second leading cause for disability worldwide and the most common neurological disorder. It is also three times more common in women; reasons for this sex difference are not known. Using preclinical behavioral models of migraine, we show that application of calcitonin gene-related peptide (CGRP) to the rat dura mater produces cutaneous periorbital hypersensitivity. Surprisingly, this response was observed only in females; dural CGRP at doses from 1 pg to 3.8 μg produce no responses in males. In females, dural CGRP causes priming to a pH 7.0 solution after animals recover from the initial CGRP-induced allodynia. Dural application of interleukin-6 causes acute responses in males and females but only causes priming to subthreshold dural CGRP (0.1 pg) in females. Intracisternal application of BDNF also causes similar acute hypersensitivity responses in males and females but only priming to subthreshold dural CGRP (0.1 pg) in females. Females were additionally primed to a subthreshold dose of the NO-donor sodium nitroprusside (0.1 mg/kg) following dural CGRP. Finally, the sexually dimorphic responses to dural CGRP were not specific to rats as similar female-specific hypersensitivity responses were seen in mice, where increased grimace responses were also observed. These data are the first to demonstrate that CGRP-induced headache-like behavioral responses at doses up to 3.8 μg are female-specific both acutely and following central and peripheral priming. These data further implicate dural CGRP signaling in the pathophysiology of migraine and propose a model where dural CGRP-based mechanisms contribute to the sexual disparity of this female-biased disorder.SIGNIFICANCE STATEMENT Calcitonin gene-related peptide (CGRP) has long been implicated in the pathophysiology of migraine, and CGRP-based therapeutics are efficacious for the treatment of migraine in humans. However, the location of action for CGRP in migraine remains unclear. We show here that application of CGRP to the cranial meninges causes behavioral responses consistent with headache in preclinical rodent models. Surprisingly, however, these responses are only observed in females. Acute responses to meningeal CGRP are female-specific and sensitization to CGRP after two distinct stimuli are also female-specific. These data implicate the dura mater as a primary location of action for CGRP in migraine and suggest that female-specific mechanisms downstream of CGRP receptor activation contribute to the higher prevalence of migraine in women.

CGRP blockade by galcanezumab was not associated with reductions in signs and symptoms of knee osteoarthritis in a randomized clinical trial

OBJECTIVE

This study tested whether galcanezumab, a humanized monoclonal antibody with efficacy against migraine, was superior to placebo for the treatment of mild or moderate osteoarthritis (OA) knee pain.

METHOD

In a multicenter, double-blind, placebo- and celecoxib-controlled trial, patients with moderate to severe OA pain were randomized to placebo; celecoxib 200 mg daily for 16 weeks; or galcanezumab 5, 50, 120, and 300 mg subcutaneously every 4 weeks, twice. The primary outcome was change from baseline at Week 8 in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscore measured by 100 mm visual analog scale (VAS). The trial was considered positive if ≥1 dose of galcanezumab demonstrated ≥95% Bayesian posterior probability of superiority to placebo and ≥50% posterior probability of superiority to placebo by ≥9 mm. A planned interim analysis allowed termination of the study if posterior probability of superiority to placebo by ≥9 mm was ≤5%. Secondary endpoints included WOMAC function subscore and Patient Global Assessment (PGA) of OA. Safety and tolerability were also assessed.

RESULTS

The study was terminated after interim analysis suggested inadequate efficacy. Celecoxib significantly reduced WOMAC pain subscore compared with placebo [-12.0 mm; 95% confidence interval (CI) -23 to -2 mm]. None of the galcanezumab arms demonstrated clinically meaningful improvement (range: 1.5 to -5.0 mm) or met the prespecified success criteria. No improvement in any secondary objective was observed. Galcanezumab was well tolerated by OA patients.

CONCLUSIONS

This study failed to demonstrate sufficient statistical evidence that galcanezumab was efficacious for treating OA knee pain.

STUDY IDENTIFICATION

NCT02192190.

Galcanezumab in chronic migraine: The randomized, double-blind, placebo-controlled REGAIN study

Objective

To evaluate the efficacy and safety of galcanezumab, a humanized monoclonal antibody that selectively binds to calcitonin gene-related peptide, in the preventive treatment of chronic migraine.

Methods

A phase 3, randomized, double-blind, placebo-controlled study of LY2951742 in patients with chronic migraine (Evaluation of Galcanezumab in the Prevention of Chronic Migraine [REGAIN]) was a phase 3 study with a 3-month double-blind, placebo-controlled treatment phase and a 9-month open-label extension. Eligible patients 18 to 65 years of age with chronic migraine were randomized 2:1:1 to monthly subcutaneous injections of placebo (n = 558), galcanezumab 120 mg (with a 240-mg loading dose, n = 278), or galcanezumab 240 mg (n = 277). The primary endpoint was the overall mean change from baseline in the number of monthly migraine headache days (MHDs) during the 3-month double-blind treatment phase.

Results

Mean number of monthly MHDs at baseline was 19.4 for the total sample. Both galcanezumab dose groups demonstrated greater overall mean reduction in the number of monthly MHDs compared to placebo (placebo −2.7, galcanezumab 120 mg −4.8, galcanezumab 240 mg −4.6) (p < 0.001 for each dose compared to placebo). There were no clinically meaningful differences between galcanezumab doses and placebo on any safety or tolerability outcome except for a higher incidence of treatment-emergent injection-site reaction (p < 0.01), injection-site erythema (p < 0.001), injection-site pruritus (p < 0.01), and sinusitis (p < 0.05) in the galcanezumab 240-mg group relative to placebo.

Conclusions

Both doses of galcanezumab were superior to placebo in reducing the number of monthly MHDs. Galcanezumab appears efficacious, safe, and well tolerated for the preventive treatment of chronic migraine.

ClinicalTrials.gov identifier

NCT02614261.

Classification of evidence

This interventional study provides Class I evidence that galcanezumab is superior to placebo in the reduction of the number of monthly MHDs.

A phase 3, long-term, open-label safety study of Galcanezumab in patients with migraine

BACKGROUND

Galcanezumab, a humanized monoclonal antibody that selectively binds to the calcitonin gene-related peptide, has demonstrated in previous Phase 2 and Phase 3 clinical studies (≤6-month of treatment) a reduction in the number of migraine headache days and improved patients' functioning. This study evaluated the safety and tolerability, as well as the effectiveness of galcanezumab for up to 12 months of treatment in patients with migraine.

METHODS

Patients diagnosed with episodic or chronic migraine, 18 to 65 years old, that were not exposed previously to galcanezumab, were randomized to receive galcanezumab 120 mg or 240 mg, administered subcutaneously once monthly for a year. Safety and tolerability were evaluated by frequency of treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), and adverse events (AEs) leading to study discontinuation. Laboratory values, vital signs, electrocardiograms, and suicidality were also analyzed. Additionally, overall change from baseline in the number of monthly migraine headache days, functioning, and disability were assessed.

RESULTS

One hundred thirty five patients were randomized to each galcanezumab dose group. The majority of patients were female (> 80%) and on average were 42 years old with 10.6 migraine headache days per month at baseline. 77.8% of the patients completed the open-label treatment phase, 3.7% of patients experienced an SAE, and 4.8% discontinued due to AEs. TEAEs with a frequency ≥ 10% of patients in either dose group were injection site pain, nasopharyngitis, upper respiratory tract infection, injection site reaction, back pain, and sinusitis. Laboratory values, vital signs, or electrocardiograms did not show anyclinically meaningful differences between galcanezumab dosesOverall mean reduction in monthly migraine headache days over 12 months for the galcanezumab dose groups were 5.6 (120 mg) and 6.5 (240 mg). Level of functioning was improved and headache-related disability was reduced in both dose groups.

CONCLUSION

Twelve months of treatment with self-administered injections of galcanezumab was safe and associated with a reduction in the number of monthly migraine headache days. Safety and tolerability of the 2 galcanezumab dosing regimens were comparable.

TRIAL REGISTRATION

ClinicalTrials.gov as NCT02614287 , posted November 15, 2015. These data were previously presented as a poster at the International Headache Congress 2017: PO-01-184, Late-Breaking Abstracts of the 2017 International Headache Congress. (2017). Cephalalgia, 37(1_suppl), 319-374.

Comparison between prefilled syringe and autoinjector devices on patient-reported experiences and pharmacokinetics in galcanezumab studies

PURPOSE

The aim of this study was to compare the usability and patient-rated experiences of an autoinjector with a prefilled syringe in patients with migraine, who self-administered galcanezumab, and to compare pharmacokinetic parameters between these devices.

MATERIALS AND METHODS

Patient-rated experiences with an investigational autoinjector and a prefilled syringe were compared in an open-label, 12-month study of once-monthly injections of galcanezumab 120 or 240 mg (NCT02614287). Patient-rated ease of usability was assessed with the Subcutaneous Administration Assessment Questionnaire (SQAAQ) and compared between devices. Positive responses on the SQAAQ were rated as "agree or strongly agree" to 12 statements. Tolerability was assessed by the frequency of injection-site-related adverse events (AEs) by device and injection location. In a separate study, galcanezumab pharmacokinetics in healthy subjects was compared between the devices (NCT02836613).

RESULTS

In the open-label clinical trial, 179 patients used both the prefilled syringe and autoinjector at least once. The majority of patients (91%-97%) had positive responses on the SQAAQ to the use of autoinjector across the items assessed. There were 23 injection-site-related AEs with the first self-administered injection with the prefilled syringe (N=7) or autoinjector (N=16; P=0.061), with the most common AE for either device being injection-site pain. There were no significant between-device differences in injection-site-related AEs. For pharmacokinetics, the 90% CI for the ratio (autoinjector/prefilled syringe) of geometric least-square means for the galcanezumab area under the curve (AUC) concentration and maximum concentration (Cmax) was between 0.8 and 1.25, indicating no statistically significant difference in the galcanezumab concentrations regardless of the device used.

CONCLUSION

The ease of usability with either device was comparable, and there were no significant differences in tolerability between the prefilled syringe and autoinjector with the first self-administration; however, the analysis was not powered to detect a clinically significant difference. Galcanezumab pharmacokinetics were comparable between devices.

Calcitonin gene-related peptide and pain: a systematic review

BACKGROUND

Calcitonin gene-related peptide (CGRP) is widely distributed in nociceptive pathways in human peripheral and central nervous system and its receptors are also expressed in pain pathways. CGRP is involved in migraine pathophysiology but its role in non-headache pain has not been clarified.

METHODS

We performed a systematic literature search on PubMed, Embase and ClinicalTrials.gov for articles on CGRP and non-headache pain covering human studies including experimental studies and randomized clinical trials.

RESULTS

The literature search identified 375 citations of which 50 contained relevant original data. An association between measured CGRP levels and somatic, visceral, neuropathic and inflammatory pain was found. In 13 out of 20 studies in somatic pain conditions, CGRP levels had a positive correlation with pain. Increased CGRP levels were reported in plasma, synovial and cerebrospinal fluid in subjects with musculoskeletal pain. A randomized clinical trial on monoclonal antibody, which selectively binds to and inhibits the activity of CGRP (galcanezumab) in patients with osteoarthritis knee pain, failed to demonstrate improvement of pain compared with placebo. No studies to date have investigated the efficacy of monoclonal antibodies against CGRP receptor in non-headache pain conditions.

CONCLUSION

The present review revealed the association between measured CGRP levels and somatic, visceral, neuropathic and inflammatory pain. These data suggest that CGRP may act as a neuromodulator in non-headache pain conditions. However, more studies are needed to fully understand the role of CGRP in nociceptive processing and therapy of chronic pain.

Gender aspects of CGRP in migraine

Background

Migraine is two to three times more prevalent in women than in men, but the mechanisms involved in this gender disparity are still poorly understood. In this respect, calcitonin gene-related peptide (CGRP) plays a key role in migraine pathophysiology and, more recently, the functional interactions between ovarian steroid hormones, CGRP and the trigeminovascular system have been recognized and studied in more detail.

Aims

To provide an overview of CGRP studies that have addressed gender differences utilizing animal and human migraine preclinical research models to highlight how the female trigeminovascular system responds differently in the presence of varying ovarian steroid hormones.

Conclusions

Gender differences are evident in migraine. Several studies indicate that fluctuations of ovarian steroid hormone (mainly estrogen) levels modulate CGRP in the trigeminovascular system during different reproductive milestones. Such interactions need to be considered when conducting future animal and human experiments, since these differences may contribute to the development of gender-specific therapies.

Phase I, Randomized, Double-blind, Placebo-controlled, Single-dose, and Multiple-dose Studies of Erenumab in Healthy Subjects and Patients With Migraine

Monoclonal antibodies (mAbs) targeting calcitonin gene-related peptide (CGRP) signaling are being explored as prophylactic treatments for migraine. Erenumab (AMG 334) is the first potent, selective, and competitive human mAb antagonist of the CGRP receptor. We report the data from two phase I studies assessing the safety, pharmacokinetics (PK), and pharmacodynamics of single and multiple administrations of erenumab in healthy subjects and patients with migraine. The results indicate that the PK profile of erenumab is nonlinear from 1 mg to 70 mg and the linear portion of the clearance from 70 mg to 210 mg is consistent with other human immunoglobulin G2 antibodies. Single doses of erenumab resulted in >75% inhibition of capsaicin-induced dermal blood flow, with no apparent dose-dependency for erenumab ≥21 mg. Erenumab was generally well tolerated, with an acceptable safety profile, supporting further clinical development of erenumab for migraine prevention.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of the CGRP Binding Monoclonal Antibody LY2951742 (Galcanezumab) in Healthy Volunteers

Background: Calcitonin gene-related peptide (CGRP) is pivotal in the pathophysiology of migraine headaches and represents a promising target for migraine treatment. The humanized monoclonal antibody galcanezumab (LY2951742) binds to CGRP and may be effective in migraine prophylaxis.

Objectives: The primary objective was to evaluate the safety and tolerability of single and multiple doses of galcanezumab in humans. Secondary objectives included assessing the pharmacokinetics and evaluating target engagement.

Methods: A double-blind, randomized, placebo-controlled study (NCT 01337596) with single escalating and multiple subcutaneous (SC) doses of galcanezumab was performed in healthy male volunteers. Single doses of 1, 5, 25, 75, 200, and 600 mg of galcanezumab (n = 7/dose) or placebo (n = 2/dose) were injected SC in six consecutive cohorts of nine subjects each. One cohort of nine subjects received multiple (4) 150 mg doses of galcanezumab or placebo every other week. Target engagement was evaluated by measuring inhibition of capsaicin-induced increase in dermal blood flow (DBF).

Findings: Sixty-three subjects were randomized and included in the safety analyses. Galcanezumab was well tolerated in single doses (1–600 mg SC) and consecutive doses (150 mg SC). There was no dose-dependent difference in type or frequency of treatment-emergent adverse events, and no clinically meaningful difference when compared with placebo. Pharmacokinetics were linear. Galcanezumab induced a robust, dose-dependent, and durable inhibition of capsaicin-induced increase in DBF, supporting the continued clinical development of galcanezumab for prophylaxis in migraine patients.

Pharmacokinetic-Pharmacodynamic Relationship of Erenumab (AMG 334) and Capsaicin-Induced Dermal Blood Flow in Healthy and Migraine Subjects

Purpose

Capsaicin-induced dermal blood flow (CIDBF) is a validated biomarker used to evaluate the target engagement of potential calcitonin gene-related peptide-blocking therapeutics for migraine. To characterize the pharmacokinetics (PK) and quantify the inhibitory effects of erenumab (AMG 334) on CIDBF, CIDBF data were pooled from a single- and a multiple-dose study in healthy and migraine subjects.

Methods

Repeated capsaicin challenges and DBF measurements were performed and serum erenumab concentrations determined. A population analysis was conducted using a nonlinear mixed-effects modeling approach. Effects of body weight, gender, and age on model parameters were evaluated.

Results

Two-compartment target-mediated drug disposition (TMDD) model assuming binding of erenumab in the central compartment best described the nonlinear PK of erenumab. Subcutaneous absorption half-life was 1.6 days and bioavailability was 74%. Erenumab produced a maximum inhibition of 89% (95% confidence interval: 87–91%). Erenumab concentrations required for 50% and 99% of maximum inhibition were 255 ng/mL and 1134 ng/mL, respectively. Increased body weight was associated with increased erenumab clearance but had no effect on the inhibitory effect on CIDBF.

Conclusions

Our results show that erenumab pharmacokinetics was best characterized by a TMDD model and resulted in potent inhibition of CIDBF.

Electronic supplementary material

The online version of this article (doi:10.1007/s11095-017-2183-6) contains supplementary material, which is available to authorized users.

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.

Heteroreceptors Modulating CGRP Release at Neurovascular Junction: Potential Therapeutic Implications on Some Vascular-Related Diseases

Calcitonin gene-related peptide (CGRP) is a 37-amino-acid neuropeptide belonging to the calcitonin gene peptide superfamily. CGRP is a potent vasodilator with potential therapeutic usefulness for treating vascular-related disease. This peptide is primarily located on C- and Aδ-fibers, which have extensive perivascular presence and a dual sensory-efferent function. Although CGRP has two major isoforms (α-CGRP and β-CGRP), the α-CGRP is the isoform related to vascular actions. Release of CGRP from afferent perivascular nerve terminals has been shown to result in vasodilatation, an effect mediated by at least one receptor (the CGRP receptor). This receptor is an atypical G-protein coupled receptor (GPCR) composed of three functional proteins: (i) the calcitonin receptor-like receptor (CRLR; a seven-transmembrane protein), (ii) the activity-modifying protein type 1 (RAMP1), and (iii) a receptor component protein (RCP). Although under physiological conditions, CGRP seems not to play an important role in vascular tone regulation, this peptide has been strongly related as a key player in migraine and other vascular-related disorders (e.g., hypertension and preeclampsia). The present review aims at providing an overview on the role of sensory fibers and CGRP release on the modulation of vascular tone.

Anti-CGRP monoclonal antibodies in migraine: current perspectives

Migraine is a highly disabling neurological pain disorder in which management is frequently problematic. Most abortive and preventative treatments employed are classically non-specific, and their efficacy and safety and tolerability are often unsatisfactory. Mechanism-based therapies are, therefore, needed. Calcitonin gene-related peptide (CGRP) is recognized as crucial in the pathophysiology of migraine, and new compounds that target the peptide have been increasingly explored in recent years. First tested were CGRP receptor antagonists; they proved effective in acute migraine treatment in several trials, but were discontinued due to liver toxicity in long-term administration. Monoclonal antibodies against CGRP (LY2951742, ALD-403, and LBR-101/TEV-48125) or its receptor (AMG334) were subsequently developed. As reviewed in this study, numerous phase 1 and 2 trials and preliminary results of phase 3 trials have shown a good safety/tolerability profile and efficacy in migraine prevention, especially in high frequent episodic and chronic forms. Being macromolecules, these mAbs are not suitable for oral administration; however, their intravenous or subcutaneous delivery can be performed at relatively low frequency-every month or even quarterly-which enhances patients' compliance. Although not all migraineurs respond to this treatment, and longer administration periods will be needed to assess long-term effects, the results so far obtained are extraordinarily promising. The future introduction of mAbs on the market will probably represent a turning point for prevention similar to that represented by triptans for abortive treatment in migraine.

The influence of migraine and female hormones on capsaicin-induced dermal blood flow

Background Migraine is much more common in females than in males, and occurrence is associated with changes in female sex hormones. Calcitonin gene-related peptide (CGRP) plays a key role in migraine, and variations in female sex hormones may affect CGRP sensitivity and/or production. Objectives Investigate repeatability, gender differences, influence of the menstrual cycle and of migraine on CGRP-dependent changes in dermal blood flow (DBF). Methods CGRP-dependent increases in DBF were assessed using laser Doppler perfusion imaging after topical application of 300 or 1000 µg capsaicin on the forearm of healthy subjects and migraine patients. Results In healthy males, DBF response did not vary over time and was comparable with DBF in male migraineurs. In healthy females, capsaicin-induced DBF responses to both doses of capsaicin were higher during menstruation compared to the late-secretory phase (p < 0.05); this menstrual cycle dependence was absent in female migraine patients. Compared to healthy subjects, female migraineurs displayed a higher DBF response both during menstruation and during the late-secretory phase (p < 0.05). Conclusions An increased capsaicin-induced, CGRP-mediated DBF response was observed during menstruation in healthy women, but in female migraine patients this increased response was not affected by the menstrual cycle.