CGRP as the target of new migraine therapies — successful translation from bench to clinic

Calcitonin gene-related peptide and intermedin induce phosphorylation of p44/42 MAPK in primary human lymphatic endothelial cells in vitro

Calcitonin gene-related peptide (CGRP) and adrenomedullin 2/intermedin (AM2/IMD) play important roles in several pathologies, including cardiovascular disease, migraine and cancer. The efficacy of drugs targeting CGRP signalling axis for the treatment of migraine patients is sometimes offset by side effects (e.g. inflammation and microvascular complications, including aberrant neovascularisation in the skin). Recent studies using animal models implicate CGRP in lymphangiogenesis and lymphatic vessel function. However, whether CGRP or AM2/IMD can act directly on lymphatic endothelial cells is unknown. Here, we found that CGRP and AM2/IMD induced p44/42 MAPK phosphorylation in a time- and dose-dependent manner in primary human dermal lymphatic endothelial cells (HDLEC) in vitro, and thus directly affected these cells. These new findings reveal CGRP and AM2/IMD as novel regulators of LEC biology and warrant further investigation of their roles in the context of pathologies associated with lymphatic function in the skin and other organs, and therapies targeting CGRP signalling axis.

Naringenin relieves paclitaxel-induced pain by suppressing calcitonin gene-related peptide signalling and enhances the anti-tumour action of paclitaxel

BACKGROUND AND PURPOSE

Chemotherapy-induced peripheral neuropathy (CIPN) commonly causes neuropathic pain, but its pathogenesis remains unclear, and effective therapies are lacking. Naringenin, a natural dihydroflavonoid compound, has anti-inflammatory, anti-nociceptive and anti-tumour activities. However, the effects of naringenin on chemotherapy-induced pain and chemotherapy effectiveness remain unexplored.

EXPERIMENTAL APPROACH

Female and male mouse models of chemotherapy-induced pain were established using paclitaxel. Effects of naringenin were assessed on pain induced by paclitaxel or calcitonin gene-related peptide (CGRP) and on CGRP expression in dorsal root ganglia (DRG) and spinal cord tissue. Additionally, we examined peripheral macrophage infiltration, glial activation, c-fos expression, DRG neuron excitability, microglial M1/M2 polarization, and phosphorylation of spinal NF-κB. Furthermore, we investigated the synergic effect and related mechanisms of naringenin and paclitaxel on cell survival of cancer cells in vitro.

KEY RESULTS

Systemic administration of naringenin attenuated paclitaxel-induced pain in both sexes. Naringenin reduced paclitaxel-enhanced CGRP expression in DRGs and the spinal cord, and alleviated CGRP-induced pain in naïve mice of both sexes. Naringenin mitigated macrophage infiltration and reversed paclitaxel-elevated c-fos expression and DRG neuron excitability. Naringenin decreased spinal glial activation and NF-κB phosphorylation in both sexes but influenced microglial M1/M2 polarization only in females. Co-administration of naringenin with paclitaxel enhanced paclitaxel's anti-tumour effect, impeded by an apoptosis inhibitor.

CONCLUSION AND IMPLICATIONS

Naringenin's anti-nociceptive mechanism involves CGRP signalling and neuroimmunoregulation. Furthermore, naringenin facilitates paclitaxel's anti-tumour action, possibly involving apoptosis. This study demonstrates naringenin's potential as a supplementary treatment in cancer therapy by mitigating side effects and potentiating efficacy of chemotherapy.

Real-world effectiveness and safety of erenumab for the treatment of migraine: A systematic review and meta-analysis

BACKGROUND

Migraine is a common and disabling primary headache disorder. Several drugs targeting calcitonin gene-related peptide (CGRP), such as erenumab (an anti-CGRP receptor mAb), have been developed recently. However, the real-world effects of erenumab are not well understood.

OBJECTIVE

To assess the clinical effectiveness and safety of erenumab for reducing migraine intensity and frequency in the real world.

METHODS

A systematic search of PubMed, Scopus, Web of Science and the Cochrane Library was conducted from inception to December 2023. Studies estimating the real-world effect of erenumab on monthly migraine days (MMD), monthly headache days (MHD), headache impact test (HIT-6), number of days in medication (NDM), acute monthly intake (AMI), pain intensity (PI) and safety outcomes were included. Meta-analyses of proportions or mean differences were performed.

RESULTS

Fifty-three studies were included. At 3-months, the effect was -7.18 days for MMD, -6.89 days for MHD, -6.97 for HIT-6, -6.22 days for NDM, -15.75 for AMI, and -1.71 for PI. Generally, the effect at 6- and 12-months increased slightly and gradually. The MMD/MHD response rates revealed that approximately one-third of patients exhibited a response greater than 30%, while one-sixth demonstrated a response exceeding 50%. Additionally, 3-4% of patients achieved a response rate of 100%. Adverse event rates were 0.34 and 0.43 at 6- and 12-months, respectively.

CONCLUSION

This study provides strong evidence of the effectiveness and safety of erenumab in the real world; to our knowledge, this is the first real-world meta-analysis specific to erenumab. Erenumab represents a solid therapeutic option for physicians.

Voltage-gated Calcium Channels as Potential Therapeutic Targets in Migraine

Migraine is a complex and highly incapacitating neurological disorder that affects around 15% of the general population with greater incidence in women, often at the most productive age of life. Migraine physiopathology is still not fully understood, but it involves multiple mediators and events in the trigeminovascular system and the central nervous system. The identification of calcitonin gene-related peptide as a key mediator in migraine physiopathology has led to the development of effective and highly selective antimigraine therapies. However, this treatment is neither accessible nor effective for all migraine sufferers. Thus, a better understanding of migraine mechanisms and the identification of potential targets are still clearly warranted. Voltage-gated calcium channels (VGCCs) are widely distributed in the trigeminovascular system, and there is accumulating evidence of their contribution to the mechanisms associated with headache pain. Several drugs used in migraine abortive or prophylactic treatment target VGCCs, which probably contributes to their analgesic effect. This review aims to summarize the current evidence of VGGC contribution to migraine physiopathology and to discuss how current pharmacological options for migraine treatment interfere with VGGC function. PERSPECTIVE: Calcitonin gene-related peptide (CGRP) represents a major migraine mediator, but few studies have investigated the relationship between CGRP and VGCCs. CGRP release is calcium channel-dependent and VGGCs are key players in familial migraine. Further studies are needed to determine whether VGCCs are suitable molecular targets for treating migraine.

An update on pharmacotherapy for trigeminal neuralgia

INTRODUCTION

Trigeminal neuralgia is a rare condition that can be effectively treated by carbamazepine or oxcarbazepine but these older drugs are associated with dose-dependent and potentially treatment-limiting adverse effects. Third-generation anticonvulsants, new calcitonin gene-related peptide blockers for migraine, and older drugs such as ketamine and cannabinoids may be promising adjuvants or monotherapeutic options.

AREAS COVERED

The new drugs, their presumed mechanisms of action, safety and efficacy are discussed herein. There is a paucity of robust clinical evidence in support of these drugs for trigeminal neuralgia. New migraine agents are considered as well although migraines and trigeminal neuralgia are distinct, albeit similar, conditions. No new drugs have been released to market in recent years with the specific indication of trigeminal neuralgia.

EXPERT OPINION

In real-world clinical practice, about half of trigeminal neuralgia patients take more than one agent for prevention and combination therapy may be the optimal approach. Combination therapy might allow for lower doses of carbamazepine or oxcarbazepine, thus reducing the number and severity of potential adverse events but the potential for pharmacokinetic drug-drug interactions must be considered. Drug therapy for trigeminal neuralgia involves acute or abortive treatments, often administered in hospital versus long-term preventive therapy, usually involving oral agents.

Molecular nociceptive mechanisms in migraine: The migraine cascade

OBJECTIVE

This review will explore the categorization of migraine-provoking molecules, their cellular actions, site of action and potential drug targets based on the migraine cascade model.

METHODS

Personal experience and literature.

RESULTS

Migraine impacts over 1 billion people worldwide but is underfunded in research. Recent progress, particularly through the human and animal provocation model, has deepened our understanding of its mechanisms. This model have identified endogenous neuropeptides such as calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide (PACAP) that induces controlled migraine-like attacks leading to significant discoveries of their role in migraine. This knowledge led to the development of CGRP-inhibiting drugs; a groundbreaking migraine treatment now accessible globally. Also a PACAP-inhibiting drug was effective in a recent phase II trial. Notably, rodent studies have shed light on pain pathways and the mechanisms of various migraine-inducing substances identifying novel drug targets. This is primarily done by using selective inhibitors that target specific signaling pathways of the known migraine triggers leading to the hypothesized cellular cascade model of migraine.

CONCLUSION

The model of migraine presents numerous opportunities for innovative drug development. The future of new migraine treatments is limited only by the investment from pharmaceutical companies.

CGRP Modulating Therapies: An Update

INTRODUCTION

Calcitonin-gene related peptide (CGRP) is a vasoactive neuropeptide involved in the pathophysiology ofmigraine. CGRP has been targeted for both preventive and acute treatment of migraine.

OBJECTIVE

Provide a summary of the most clinically relevant literature surrounding CGRP modulating therapies.

METHODS

This update on CGRP modulating therapies includes articles selected as most clinically relevant by theauthors.

CONCLUSION

CGRP modulating therapies are an exciting new addition to migraine treatment given their safety andtolerability. Additionally, compared to traditional migraine preventive medication these treatments are migrainespecific.Further real-world and clinical data is ongoing to better understand these treatments that continue to gainfavor in the management of migraine.

Impact of duration of chronic migraine on long-term effectiveness of monoclonal antibodies targeting the calcitonin gene-related peptide pathway-A real-world study

OBJECTIVE

We assessed whether the effectiveness of monoclonal antibodies (mAbs) targeting the calcitonin gene-related peptide (CGRP) pathway changes according to the duration of chronic migraine (CM) over 12 months.

BACKGROUND

In most patients, CM is a progressive disease starting with episodic migraine. Longer CM duration might be associated with more difficult treatment, probably because the mechanisms underlying chronicization are strengthened. Therefore, early treatment of CM could lead to better outcomes compared with later treatment.

METHODS

This cohort study included individuals with CM treated with anti-CGRP mAbs in two tertiary headache centers from April 2019 to May 2023. The primary outcome included a change in monthly migraine days (MMDs) from baseline to the third trimester of treatment, 10-12 months. Secondary outcomes established whether response to anti-CGRP mAbs has a more rapid onset in individuals with shorter CM duration compared with longer duration; they included change in MMDs, monthly headache days (MHDs), and days and number of intakes of acute medication during each trimester compared to baseline. Additional outcomes included persisting MMDs, MHDs, and days and number of intakes of acute medication during each trimester of treatment. Patients were compared across tertiles of the overall CM duration.

RESULTS

The study included 335 individuals with CM, with a median (interquartile range [IQR]) age of 48 (39-57) years; 270 (80.6%) were women. Patients in the highest tertile of CM duration (aged 18-60 years) were older than patients in the lower duration tertiles (0-7 years and 8-18 years, respectively), with a median (IQR) age of 56 (48-64) years compared with 42 (31-50) years, and 48 (39-56)years, respectively (p = 0.025); however, this difference was likely due to a correlation between age and disease duration. The change in MMDs from baseline to the last trimester of treatment (10-12 months) was comparable across tertiles of CM duration (median [IQR] -12 [-18 to -5] days, -12 [-17 to -6] days, and -12 [-18 to -4] days; p = 0.946). No difference emerged in secondary outcomes, suggesting a similar time to onset of anti-CGRP mAbs effect across all tertiles of CM duration.

CONCLUSIONS

Our data showed that anti-CGRP mAbs are effective and have a rapid onset of action in CM regardless of disease duration.

Trigeminal ganglion neurons are directly activated by influx of CSF solutes in a migraine model

Classical migraine patients experience aura, which is transient neurological deficits associated with cortical spreading depression (CSD), preceding headache attacks. It is not currently understood how a pathological event in cortex can affect peripheral sensory neurons. In this study, we show that cerebrospinal fluid (CSF) flows into the trigeminal ganglion, establishing nonsynaptic signaling between brain and trigeminal cells. After CSD, ~11% of the CSF proteome is altered, with up-regulation of proteins that directly activate receptors in the trigeminal ganglion. CSF collected from animals exposed to CSD activates trigeminal neurons in naïve mice in part by CSF-borne calcitonin gene-related peptide (CGRP). We identify a communication pathway between the central and peripheral nervous system that might explain the relationship between migrainous aura and headache.

Animal Models of Chronic Migraine: From the Bench to Therapy

PURPOSE OF REVIEW

Chronic migraine is a disabling progressive disorder without effective management approaches. Animal models have been developed and used in chronic migraine research. However, there are several problems with existing models. Therefore, we aimed to summarize and analyze existing animal models to facilitate translation from basic to clinical.

RECENT FINDINGS

The most commonly used models are the inflammatory soup induction model and the nitric oxide donor induction model. In addition, KATP openers have also been used in model induction. Based on the above models, some molecular targets have been identified, such as glutamate receptors. However, each model has its shortcomings and characteristics, and there are still some common problems that need to be solved, such as spontaneous headache, evaluation criteria after model establishment, and identification methods. In this review, we summarized and highlighted the advantages and limitations of the currently commonly used animal models of chronic migraine with a special focus on drug discovery and current therapeutic strategies, and discussed the directions that can be worked on in the future.

[CGRP: from neuropeptide to the therapeutic target (background and pathophysiology)]

Calcitonin gene-related peptide (CGRP) plays a pivotal role in migraine pathophysiology. The importance of CGRP in migraine became evident from numerous clinical studies investigating CGRP levels both interictally and ictally and reports on the efficacy of CGRP-based migraine therapies. In this paper, the above mentioned studies will be presented and the reader will be introduced to the development of CGRP-based medication. Finally, current study results on CGRP receptor antagonists, the so-called gepants, will be presented.

A real-world prospective observational study of eptinezumab in Asian patients with migraine

OBJECTIVE

To evaluate the real-world effectiveness of eptinezumab for migraine prevention in Asian patients.

BACKGROUND

Eptinezumab is a monoclonal antibody that targets calcitonin gene-related peptide (CGRP), a potent vasodilator with an important role in migraine pathophysiology. Although there is robust clinical evidence from pivotal Phase 3 placebo-controlled trials of the efficacy of eptinezumab for migraine prevention, there are limited data on the real-world effectiveness of eptinezumab in Asian patient cohorts.

METHODS

This was a non-interventional, prospective, multisite cohort study of adults with migraine (International Classification of Headache Disorders, 3rd edition criteria) in Singapore who were prescribed eptinezumab (100 mg at baseline and Month 3, administered intravenously) and were followed until Month 6. The primary endpoint was change from baseline in monthly migraine days (MMDs) at Month 3 and Month 6. Secondary endpoints were ≥30% and ≥50% responder rates, and change from baseline in the Headache Impact Test-6 (HIT-6), Migraine Disability Assessment (MIDAS), Migraine-Specific Quality of Life (MSQ), patient-identified most bothersome symptom (PI-MBS), acute medication use at Month 3 and Month 6, and safety.

RESULTS

Enrolled patients (completed = 29/30) had on average 3.4 (SD 2.9) previous preventive treatments; 29/30 of the patients had trialed at least one previous preventive treatment without benefit. Most had previously trialed oral preventives (87%, 26/30) and anti-CGRP (70%, 21/30). Relative to baseline, mean MMDs decreased by 4.3 days (95% CI 2.1-6.4; p < 0.001) at Month 3 and 4.9 days (95% CI 2.1-7.7; p < 0.001) at Month 6. At Month 3 and Month 6, 14/30 (47%) and 15/29 (52%) of the patients were ≥30% responders, and 6/30 (20%) and 8/29 (28%) patients were ≥50% responders, respectively. The number of patients with severe life impairment based on the HIT-6 score (total score 60-78) decreased from 24/30 (80%) at baseline to 19/30 (63%) at Month 3 and 19/29 (66%) at Month 6. The mean MIDAS score decreased by 24.6 points (95% CI 2.82-46.38; p = 0.028) at Month 6, and the mean MSQ score increased by 12.2 points (95% CI 5.18-19.20; p = 0.001) at Month 3 and 13.6 points (95% CI 4.58-22.66; p = 0.004) at Month 6. Most patients reported improvement in the PI-MBS at Month 3 (73%, 22/30) and Month 6 (55%, 16/29). Acute medication use for headache relief decreased by 3.3 days/month (95% CI 1.0-5.6; p = 0.007) at Month 3 and 4.7 days/month (95% CI 1.7-7.7; p = 0.003) at Month 6. Treatment-emergent adverse events (TEAEs) were reported in 16/30 (54%) patients, mostly mild/moderate in severity. No serious TEAEs led to treatment discontinuation.

CONCLUSION

Quarterly eptinezumab administration was effective and well-tolerated in Asian patients with chronic migraine.

Pituitary cyclase-activating polypeptide targeted treatments for the treatment of primary headache disorders

OBJECTIVE

Migraine is a complex and disabling neurological disorder. Recent years have witnessed the development and emergence of novel treatments for the condition, namely those targeting calcitonin gene-related peptide (CGRP). However, there remains a substantial need for further treatments for those unresponsive to current therapies. Targeting pituitary adenylate cyclase-activating polypeptide (PACAP) as a possible therapeutic strategy in the primary headache disorders has gained interest over recent years.

METHODS

This review will summarize what we know about PACAP to date: its expression, receptors, roles in migraine and cluster headache biology, insights gained from preclinical and clinical models of migraine, and therapeutic scope.

RESULTS

PACAP shares homology with vasoactive intestinal polypeptide (VIP) and is one of several vasoactive neuropeptides along with CGRP and VIP, which has been implicated in migraine neurobiology. PACAP is widely expressed in areas of interest in migraine pathophysiology, such as the thalamus, trigeminal nucleus caudalis, and sphenopalatine ganglion. Preclinical evidence suggests a role for PACAP in trigeminovascular sensitization, while clinical evidence shows ictal release of PACAP in migraine and intravenous infusion of PACAP triggering attacks in susceptible individuals. PACAP leads to dural vasodilatation and secondary central phenomena via its binding to different G-protein-coupled receptors, and intracellular downstream effects through cyclic adenosine monophosphate (cAMP) and phosphokinase C (PKC). Targeting PACAP as a therapeutic strategy in headache has been explored using monoclonal antibodies developed against PACAP and against the PAC1 receptor, with initial positive results.

INTERPRETATION

Future clinical trials hold considerable promise for a new therapeutic approach using PACAP-targeted therapies in both migraine and cluster headache.

Neurobiological mechanisms of botulinum neurotoxin-induced analgesia for neuropathic pain

Botulinum neurotoxins (BoNTs) are a family of neurotoxins produced by Clostridia and other bacteria that induce botulism. BoNTs are internalized into nerve terminals at the site of injection and cleave soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins to inhibit the vesicular release of neurotransmitters. BoNTs have been approved for multiple therapeutic applications, including the treatment of migraines. They have also shown efficacies for treating neuropathic pain, such as diabetic neuropathy, and postherpetic and trigeminal neuralgia. However, the mechanisms underlying BoNT-induced analgesia are not well understood. Peripherally administered BoNT is taken up by the nerve terminals and reduces the release of glutamate, calcitonin gene-related peptide, and substance P, which decreases neurogenic inflammation in the periphery. BoNT is retrogradely transported to sensory ganglia and central terminals in a microtubule-dependent manner. BoNTs decrease the expression of pronociceptive genes (ion channels or cytokines) from sensory ganglia and the release of neurotransmitters and neuropeptides from primary afferent central terminals, which likely leads to decreased central sensitization in the dorsal horn of the spinal cord or trigeminal nucleus. BoNT-induced analgesia is abolished after capsaicin-induced denervation of transient receptor potential vanilloid 1 (TRPV1)-expressing afferents or the knockout of substance P or the neurokinin-1 receptor. Although peripheral administration of BoNT leads to changes in the central nervous system (e.g., decreased phosphorylation of glutamate receptors in second-order neurons, reduced activation of microglia, contralateral localization, and cortical reorganization), whether such changes are secondary to changes in primary afferents or directly mediated by trans-synaptic, transcytotic, or the hematogenous transport of BoNT is controversial. To enhance their therapeutic potential, BoNTs engineered for specific targeting of nociceptive pathways have been developed to treat chronic pain. Further mechanistic studies on BoNT-induced analgesia can enhance the application of native or engineered BoNTs for neuropathic pain treatment with improved safety and efficacy.

Empowerment, Pain Control, and Quality of Life Improvement in Early Triple-Negative Breast Cancer Patients through Pain Neuroscience Education: A Prospective Cohort Pilot Study Protocol (EMPOWER Trial)

The treatment of early triple-negative breast cancer (eTNBC) has improved patients' prognosis but often leads to adverse events and sequelae affecting quality of life (QoL). Pain Neuroscience Education (PNE) is a promising non-pharmacological intervention in this field. Preliminary data have shown the beneficial effect of PNE in BC survivors. However, there are still gaps in knowledge regarding its optimal use in eTNBC. To address this issue, a prospective pilot study will enroll 30 consecutive patients diagnosed with eTNBC at IRCCS Humanitas Research Hospital. The PNE program will consist of 10 weekly sessions to be started within 4 weeks of the onset or worsening of a pain syndrome (PS). QoL, pain, and disability will be assessed before, during, at the end of, and 6 months after PNE using validated questionnaires. Peripheral venous blood samples will be taken before and at the end of PNE to evaluate inflammatory serum biomarker levels. The primary objective is to evaluate whether PNE leads to clinical improvement in QoL and pain. If successful, it will be validated in a larger multi-centric cohort, potentially leading to its widespread implementation as a standard pain management tool for eTNBC patients.

The preclinical discovery and development of atogepant for migraine prophylaxis

INTRODUCTION

Atogepant is a selective calcitonin gene-related peptide (CGRP) receptor antagonist that is utilized in adults for the prevention of episodic and chronic migraine. Cumulative findings support the involvement of CGRP in migraine pathophysiology, and atogepant functions by competitively antagonizing CGRP receptors, which results in the inhibition of trigeminovascular nociception. The mechanism of action addresses the cause of migraine pain, providing an effective preventive treatment option.

AREAS COVERED

The key milestones in its development, including preclinical achievements, phase I, II, and III clinical trials, and regulatory approvals are reviewed. Additionally, clinical efficacy, safety profile, and tolerability of atogepant are discussed. The literature review is based on a comprehensive search of English peer-reviewed articles from various electronic databases, including PubMed and ClinicalTrials.gov.

EXPERT OPINION

The development of atogepant represents a significant breakthrough in migraine prevention, particularly due to its improved safety profile that reduces the risk of liver injury, which was a major limitation of first-generation gepants. Drug-drug interaction studies with atogepant highlight the necessity for more inclusive study populations. Given that migraine disproportionately affects females, future clinical development programs should include diverse patient demographics to ensure the findings are generalizable to all individuals suffering from migraine.

Effects of Transcranial Ultrasound Stimulation on Blood Oxygen Metabolism and Brain Rhythms in Nitroglycerin-Induced Migraine Mice

OBJECTIVES

In this study, we aimed to investigate the regulatory mechanism of transcranial ultrasound stimulation (TUS) on nitroglycerin-induced migraine in mice.

MATERIALS AND METHODS

The experiment was divided into four groups, namely, the normal saline control group (n = 9), ultrasound stimulation control group (n = 6), nitroglycerin-induced migraine group (n = 9), and ultrasound stimulation group (n = 9). The behavior, blood oxygen metabolism, and brain rhythm distribution of the four groups were analyzed.

RESULTS

We found that after TUS, the movement time and speed of mice with migraine are modulated to those of the control groups, and the number of head scratching and grooming events is significantly reduced. TUS increased the deoxygenated hemoglobin, and the power of the 4-to-40 Hz frequency band of local field potentials in the cortex of migraine mice. TUS also decreased the expression of plasma calcitonin gene-related peptide and cortical c-Fos protein.

CONCLUSIONS

Ultrasound stimulation can regulate brain rhythm and blood oxygen metabolism and reduce migraine symptoms in mice. The regulatory mechanism may be related to reducing calcitonin gene-related peptide in blood vessels.

Additional effect of erenumab for patients with chronic migraine treated with onabotulinumtoxin A-real-world data from a preliminary cohort study

Background

This preliminary retrospective cohort study investigates the potential additive prophylactic effect of erenumab, a fully human monoclonal antibody that blocks the calcitonin gene-related peptide receptor, in combination with ongoing onabotulinumtoxin A (onaBoNT-A) treatment in patients suffering from chronic migraine.

Methods

The study included 218 patients and investigated the effects of adding erenumab to the existing treatment regimen. The primary outcome was the MIDAS (Migraine Disability Assessment) score assessed 3 months after the introduction of erenumab.

Results

The results indicated a significant improvement of the MIDAS score, suggesting a reduction in migraine-related disability following the addition of erenumab to onaBoNT-A. In the inter group comparison, dual therapy showed a significantly greater reduction of the MIDAS when compared to a switch from onaBoNT-A to erenumab monotherapy, but not compared to initiation of onaBoNT-A monotherapy. It is hypothesized that the observed additive effects are due to the independent modes of action of erenumab and onabotulinumtoxin A.

Conclusion

This study suggests that the combination of erenumab with onaBoNT-A may offer an improved approach for the treatment of chronic migraine in selected patients. However, the results highlight the need for prospective, controlled studies to validate these findings and determine the optimal combination of treatments tailored to the individual patient.

The evolving landscape and research trend of calcitonin gene-related peptide in migraine: A bibliometric analysis and visualization

Background

Migraine is a global public health concern, affecting both social and individual well-being. Calcitonin gene-related peptide (CGRP), a crucial neuropeptide, holds important research value in understanding migraine pathogenesis. CGRP receptor antagonists and monoclonal antibodies that target CGRP or its receptors have shown efficacy in reducing migraine frequency and severity, presenting a promising therapeutic approach. This study aimed to conduct a comprehensive bibliometric analysis to analyze the current state, research trends, and future directions of CGRP in migraine.

Methods

Bibliometric tools including CiteSpace, VOSviewer, etc., were utilized to extract and summarize publications related to CGRP in migraine from the Web of Science Core Collection Database (WOSCC) between 2004 and 2023, as of December 31, 2023. The analysis focused on trends in annual publications, leading countries/regions and institutions, prominent journals and references, influential authors, and high-frequency keywords in the field.

Results

A total of 1,821 articles and reviews involving 5,180 authors from 1,315 organizations across 64 countries were included in the study. These publications were distributed across 362 journals and accumulated 56,999 citations by December 31, 2023. An increasing trend was observed in annual publications on CGRP in migraine. The United States emerged as the leading nation in both publications and citations, with academic Peter Goadsby contributing the highest number of publications. The University of Copenhagen stood out as the institution with the most publications, and Cephalalgia emerged as the most influential journal. The most cited paper identified was "Calcitonin gene-related peptide receptor antagonist BIBN4096BS for the acute treatment of migraine" by Jes Olesen, published in the New Engl Med. Keyword frequency analysis revealed prevalent terms such as "migraine," "CGRP," and "episodic migraine," along with emerging topics represented by keywords including "trial," "monoclonal antibodies," "preventive treatment," and "safety."

Conclusion

CGRP is pivotal in migraine pathogenesis, and there is a robust research foundation exploring its role. The US leads in research output on CGRP in migraine. Investigating the mechanism of CGRP and its receptor in migraine remains a key area of interest, particularly focusing on signaling pathways. Future research should target identifying critical therapeutic targets in CGRP antagonist pathways for migraine treatment.

Provocation of attacks to discover migraine signaling mechanisms and new drug targets: early history and future perspectives - a narrative review

INTRODUCTION

The development of several experimental migraine provocation models has significantly contributed to an understanding of the signaling mechanisms of migraine. The early history of this development and a view to the future are presented as viewed by the inventor of the models.

METHODS

Extensive knowledge of the literature was supplemented by scrutiny of reference lists.

RESULTS

Early studies used methodologies that were not blinded. They suggested that histamine and nitroglycerin (Glyceryl trinitrate, GTN) could induce headache and perhaps migraine. The development of a double blind, placebo-controlled model, and the use of explicit diagnostic criteria for induced migraine was a major step forward. GTN, donor of nitric oxide (NO), induced headache in people with- and without migraine as well as delayed migraine attacks in those with migraine. Calcitonin gene-related peptide (CGRP) did the same, supporting the development of CGRP antagonists now widely used in patients. Likewise, pituitary adenylate cyclase activating peptide (PACAP) provoked headache and migraine. Recently a PACAP antibody has shown anti migraine activity in a phase 2 trial. Increase of second messengers activated by NO, CGRP and PACAP effectively induced migraine. The experimental models have also been used in other types of headaches and have been combined with imaging and biochemical studies. They have also been used for drug testing and in genetic studies.

CONCLUSION

Conclusion. Human migraine provocation models have informed about signaling mechanisms of migraine leading to new drugs and drug targets. Future use of these models in imaging-, biochemistry- and genetic studies as well as in the further study of animal models is promising.

Macrocyclization strategy for improving candidate profiles in medicinal chemistry

Macrocycles are defined as cyclic compounds with 12 or more members. In medicinal chemistry, they are categorized based on their core chemistry into cyclic peptides and macrocycles. Macrocycles are advantageous because of their structural diversity and ability to achieve high affinity and selectivity towards challenging targets that are often not addressable by conventional small molecules. The potential of macrocyclization to optimize drug-like properties while maintaining adequate bioavailability and permeability has been emphasized as a key innovation in medicinal chemistry. This review provides a detailed case study of the application of macrocyclization over the past 5 years, starting from the initial analysis of acyclic active compounds to optimization of the resulting macrocycles for improved efficacy and drug-like properties. Additionally, it illustrates the strategic value of macrocyclization in contemporary drug discovery efforts.

Plasma calcitonin gene-related peptide levels in idiopathic intracranial hypertension: an exploratory study

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a debilitating condition characterized by increased intracranial pressure often presenting with chronic migraine-like headache. Calcitonin gene-related peptide (CGRP) plays an important pathophysiological role in primary headaches such as migraine, whilst its role in IIH has not yet been established.

METHODS

This longitudinal exploratory study included patients with IIH, episodic migraine (EM) in a headache-free interval and healthy controls (HC). Blood samples were collected from a cubital vein and plasma CGRP (pCGRP) levels were measured by standardized ELISA.

RESULTS

A total of 26 patients with IIH (mean age 33.2 years [SD 9.2], 88.5% female, median BMI 34.8 kg/m2 [IQR 30.0-41.4]), 30 patients with EM (mean age 27.6 years [7.5], 66.7% female) and 57 HC (mean age 25.3 years [5.2], 56.1% female) were included. pCGRP levels displayed a wide variation in IIH as well as in EM and HC on a group-level. Within IIH, those with migraine-like headache had significantly higher pCGRP levels than those with non-migraine-like headache (F(2,524) = 84.79; p < 0.001) and headache absence (F(2,524) = 84.79; p < 0.001) throughout the observation period, explaining 14.7% of the variance in pCGRP levels. CGRP measurements showed strong intraindividual agreement in IIH (ICC 0.993, 95% CI 0.987-0.996, p < 0.001). No association was found between pCGRP levels and ophthalmological parameters.

CONCLUSIONS

Although interindividual heterogeneity of pCGRP levels is generally high, migraine-like headache seems to be associated with higher pCGRP levels. CGRP may play a role in the headache pathophysiology at least in a subgroup of IIH.

Therapeutic patterns and migraine disease burden in switchers of CGRP-targeted monoclonal antibodies - insights from the German NeuroTransData registry

BACKGROUND

Monoclonal antibodies (mAbs) targeting the calcitonin gene-related peptide (CGRP) pathway have shown good efficacy in migraine prophylaxis. However, a subset of patients does not respond to the first mAb treatment and switches among the available mAbs. The goal of this study is to characterize the switching pattern of migraine patients treated with anti-CGRP(-receptor, -R) mAbs, and to describe the headache burden of those who did not switch, switched once, and switched twice.

METHODS

This study used real world data from the NeuroTransData Cohort, a registry of migraine patients treated at outpatient neurology clinics across Germany. Patients who had received at least one anti-CGRP(-R) mAb were included. Headache diaries were collected at baseline and during treatment, along with quality of life measures every three months. Results were summarized for the subgroups of patients who did not switch and those with one and two switches.

RESULTS

Of the 655 eligible patients, 479 did not switch, 135 switched once, 35 twice, and 6 three or more times. The ≥ 50% response rates for monthly migraine days were 64.7%, 50.7%, and 25.0% for the no switch, one switch, and two switches groups in their last treatment cycles, respectively. Quality of life measures improved for the no switch and one switch groups, but not for the two switches group.

CONCLUSION

Patients who switched among anti-CGRP(-R) mAbs during the course of their treatment still benefited overall but to a lesser extent than those who did not switch. Treatment response in patients who switched twice was markedly lower compared to the no switch and one switch subgroup.

BDNF-VGF Pathway Aggravates Incision Induced Acute Postoperative Pain via Upregulating the Neuroinflammation in Dorsal Root Ganglia

Approximately one-third of postoperative patients are troubled by postoperative pain. Effective treatments are still lacking. The aim of this study is to investigate the role of brain-derived neurotrophic factor (BDNF)-VGF (non-acronymic) in dorsal root ganglia (DRG) in postoperative pain. Pain behaviors were assessed through measurements of paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). Transcriptome analysis was conducted to identify potential targets associated with postoperative pain. Western blotting, immunofluorescence, and ELISA were employed to further detect macrophage activation as well as the expression of BDNF, VGF, TNF-α, IL-1β, and IL-6. Results showed that plantar incision induced both mechanical and thermal hyperalgesia. Transcriptome analysis suggested that plantar incision caused upregulation of BDNF and VGF. The expressions of BDNF and VGF were upregulated in isolectin B4-positive (IB4+) and calcitonin gene-related peptide-positive (CGRP+) neurons, rather than neurofilament 200-positive (NF200+) neurons. The activation of BDNF-VGF pathway upregulated expression of IL-6, TNF-α, and IL-1β and promoted the activation of macrophages. In conclusion, BDNF-VGF pathway aggravates acute postoperative pain by promoting macrophage activation and pro-inflammatory cytokine production, which may provide a new target for the treatment of postoperative pain.

The impact of the migraine treatment onabotulinumtoxinA on inflammatory and pain responses: Insights from an animal model

OBJECTIVE

Migraine, a prevalent and debilitating disease, involves complex pathophysiology possibly including inflammation and heightened pain sensitivity. The current study utilized the complete Freund's adjuvant (CFA) model of inflammation, with onabotulinumtoxinA (BoNT/A) as a treatment of interest due to its use in clinical migraine management. Using an animal model, the study sought to investigate the role of BoNT/A in modulating CFA-induced inflammation, alterations in pain sensitivity, and the regulation of calcitonin gene-related peptide (CGRP) release. Further, we aimed to assess the changes in SNAP-25 through western blot analysis to gain insights into the mechanistic action of BoNT/A.

METHODS

BoNT/A or control was administered subcutaneously at the periorbital region of rats 3 days before the induction of inflammation using CFA. Periorbital mechanical sensitivity was assessed post-inflammation, and alterations in CGRP release were evaluated. Changes in SNAP-25 levels were determined using western blot analysis.

RESULTS

Upon CFA-induced inflammation, there was a marked increase in periorbital mechanical sensitivity, with the inflammation side showing increased sensitivity compared to other periorbital areas. BoNT/A did decrease the withdrawal thresholds in the electronic von Frey test. Despite not being able to observe differences in pain thresholds or CGRP release, BoNT/A reduced baseline release under CFA inflamed conditions. Analysis of SNAP-25 levels in the trigeminal ganglion revealed both intact and cleaved forms that were notably elevated in BoNT/A-treated animals. These findings, derived from western blot analysis, suggest an effect on neurotransmitter release.

CONCLUSION

Our investigation highlights the role of BoNT/A in reducing baseline CGRP in the context of inflammation and its involvement in SNAP-25 cleavage. In contrast, BoNT/A did not appear to alter facial pain sensitivity induced by inflammation, suggesting that mechanisms other than baseline CGRP could be implicated in the elevated thresholds in the CFA model.

Quantitative proteomics reveals CLR interactome in primary human cells

The G protein-coupled receptor (GPCR) calcitonin receptor-like receptor (CLR) mediates essential functions in several cell types and is implicated in cardiovascular pathologies, skin diseases, migraine, and cancer. To date, the network of proteins interacting with CLR ("CLR interactome") in primary cells, where this GPCR is expressed at endogenous (physiologically relevant) levels, remains unknown. To address this knowledge gap, we established a novel integrative methodological workflow/approach for conducting a comprehensive/proteome-wide analysis of Homo sapiens CLR interactome. We used primary human dermal lymphatic endothelial cells and combined immunoprecipitation utilizing anti-human CLR antibody with label-free quantitative nano LC-MS/MS and quantitative in situ proximity ligation assay. By using this workflow, we identified 37 proteins interacting with endogenously expressed CLR amongst 4902 detected members of the cellular proteome (by quantitative nano LC-MS/MS) and revealed direct interactions of two kinases and two transporters with this GPCR (by in situ proximity ligation assay). All identified interactors have not been previously reported as members of CLR interactome. Our approach and findings uncover the hitherto unrecognized compositional complexity of the interactome of endogenously expressed CLR and contribute to fundamental understanding of the biology of this GPCR. Collectively, our study provides a first-of-its-kind integrative methodological approach and datasets as valuable resources and robust platform/springboard for advancing the discovery and comprehensive characterization of physiologically relevant CLR interactome at a proteome-wide level in a range of cell types and diseases in future studies.

Pharmacokinetics of Ubrogepant in Healthy Japanese and White Adults

Ubrogepant is a calcitonin gene-related peptide receptor antagonist indicated for the acute treatment of migraine with or without aura in adults. The objectives of this study were to evaluate (1) single-dose pharmacokinetics (PK) and dose proportionality of ubrogepant in Japanese participants, (2) the safety and tolerability of ubrogepant in healthy Japanese and White participants, and (3) to compare the PK of ubrogepant in Japanese versus White participants. A total of 48 participants were enrolled into 4 cohorts (N = 12 [9 active + 3 placebo] per cohort). A single dose was administered on Day 1 following an overnight fast to assess the PK of ubrogepant at 3 dose levels and test dose proportionality between 25 and 100 mg in Japanese participants. White participants were randomly assigned to ubrogepant (100 mg) or placebo. Dose proportionality was observed in the dose range of 25-100 mg in Japanese participants. Systemic exposure was 20% lower in Japanese participants as compared with White participants, but this difference is unlikely to be clinically relevant. Single doses of ubrogepant (25-100 mg) had a safety profile similar to placebo, and no differences in the safety profile of ubrogepant 100 mg were observed between Japanese versus White participants.

Alleviation of migraine related pain and anxiety by inhibiting calcium-stimulating AC1-dependent CGRP in the insula of adult rats

BACKGROUND

Recent animal and clinical findings consistently highlight the critical role of calcitonin gene-related peptide (CGRP) in chronic migraine (CM) and related emotional responses. CGRP antibodies and receptor antagonists have been approved for CM treatment. However, the underlying CGRP-related signaling pathways in the pain-related cortex remain poorly understood.

METHODS

The SD rats were used to establish the CM model by dural infusions of inflammatory soup. Periorbital mechanical thresholds were assessed using von-Frey filaments, and anxiety-like behaviors were observed via open field and elevated plus maze tests. Expression of c-Fos, CGRP and NMDA GluN2B receptors was detected using immunofluorescence and western blotting analyses. The excitatory synaptic transmission was detected by whole-cell patch-clamp recording. A human-used adenylate cyclase 1 (AC1) inhibitor, hNB001, was applied via insula stereotaxic and intraperitoneal injections in CM rats.

RESULTS

The insular cortex (IC) was activated in the migraine model rats. Glutamate-mediated excitatory transmission and NMDA GluN2B receptors in the IC were potentiated. CGRP levels in the IC significantly increased during nociceptive and anxiety-like activities. Locally applied hNB001 in the IC or intraperitoneally alleviated periorbital mechanical thresholds and anxiety behaviors in migraine rats. Furthermore, CGRP expression in the IC decreased after the hNB001 application.

CONCLUSIONS

Our study indicated that AC1-dependent IC plasticity contributes to migraine and AC1 may be a promising target for treating migraine in the future.

Meningeal lymphatic CGRP signaling governs pain via cerebrospinal fluid efflux and neuroinflammation in migraine models

Recently developed antimigraine therapeutics targeting calcitonin gene-related peptide (CGRP) signaling are effective, though their sites of activity remain elusive. Notably, the lymphatic vasculature is responsive to CGRP signaling, but whether meningeal lymphatic vessels (MLVs) contribute to migraine pathophysiology is unknown. Mice with lymphatic vasculature deficient in the CGRP receptor (CalcrliLEC mice) treated with nitroglycerin-mediated (NTG-mediated) chronic migraine exhibit reduced pain and light avoidance compared with NTG-treated littermate controls. Gene expression profiles of lymphatic endothelial cells (LECs) isolated from the meninges of Rpl22HA/+;Lyve1Cre RiboTag mice treated with NTG revealed increased MLV-immune interactions compared with cells from untreated mice. Interestingly, the relative abundance of mucosal vascular addressin cell adhesion molecule 1-interacting (MAdCAM1-interacting) CD4+ T cells was increased in the deep cervical lymph nodes of NTG-treated control mice but not in NTG-treated CalcrliLEC mice. Treatment of cultured hLECs with CGRP peptide in vitro induced vascular endothelial-cadherin (VE-cadherin) rearrangement and reduced functional permeability. Likewise, intra cisterna magna injection of CGRP caused rearrangement of VE-cadherin, decreased MLV uptake of cerebrospinal fluid (CSF), and impaired CSF drainage in control mice but not in CalcrliLEC mice. Collectively, these findings reveal a previously unrecognized role for lymphatics in chronic migraine, whereby CGRP signaling primes MLV-immune interactions and reduces CSF efflux.

Cryo-EM Structure of the Human Amylin 1 Receptor in Complex with CGRP and Gs Protein

Inhibition of calcitonin gene-related peptide (CGRP) or its cognate CGRP receptor (CGRPR) has arisen as a major breakthrough in the treatment of migraine. However, a second CGRP-responsive receptor exists, the amylin (Amy) 1 receptor (AMY1R), yet its involvement in the pathology of migraine is poorly understood. AMY1R and CGRPR are heterodimers consisting of receptor activity-modifying protein 1 (RAMP1) with the calcitonin receptor (CTR) and the calcitonin receptor-like receptor (CLR), respectively. Here, we present the structure of AMY1R in complex with CGRP and Gs protein and compare it with the reported structures of the AMY1R complex with rat amylin (rAmy) and the CGRPR in complex with CGRP. Despite similar protein backbones observed within the receptors and the N- and C-termini of the two peptides bound to the AMY1R complexes, they have distinct organization in the peptide midregions (the bypass motif) that is correlated with differences in the dynamics of the respective receptor extracellular domains. Moreover, divergent conformations of extracellular loop (ECL) 3, intracellular loop (ICL) 2, and ICL3 within the CTR and CLR protomers are evident when comparing the CGRP bound to the CGRPR and AMY1R, which influences the binding mode of CGRP. However, the conserved interactions made by the C-terminus of CGRP to the CGRPR and AMY1R are likely to account for cross-reactivity of nonpeptide CGRPR antagonists observed at AMY1R, which also extends to other clinically used CGRPR blockers, including antibodies.

Treatment Outcome After Switching From Galcanezumab to Fremanezumab in Patients With Migraine

BACKGROUND AND PURPOSE

Monoclonal antibodies (mAbs) targeting calcitonin-gene-related peptide (CGRP) or its receptor (anti-CGRP-R) have been widely administered to patients with migraine who show inadequate responses to preventive medications. Among patients in whom a particular anti-CGRP-R mAb is ineffective, switching between different anti-CGRP-R mAbs can be the next option. Few studies have investigated treatment outcomes for antibody switching, especially between mAbs with the same target of the CGRP ligand. We aimed to determine the treatment outcome after switching between two anti-CGRP mAbs (galcanezumab to fremanezumab).

METHODS

We identified migraine patients in a prospective headache clinic registry who received galcanezumab for ≥3 months and were switched to fremanezumab for a further ≥3 months at a single university hospital. We defined a treatment response as a ≥50% reduction in the number of days with a moderate or severe headache at the third month of treatment relative to baseline. The treatment response after switching to fremanezumab was compared with the initial treatment response to galcanezumab.

RESULTS

Among 21 patients identified in the registry, 7 (33.3%) were initial responders to galcanezumab. After switching to fremanezumab, 7 (33.3%) showed a treatment response. The treatment response rate was 28.6% in the initial responders and 71.4% in the nonresponders to galcanezumab (p>0.999).

CONCLUSIONS

Switching between anti-CGRP mAbs (galcanezumab to fremanezumab) yielded a treatment outcome comparable to that reported previously when switching from an anti-CGRP-R mAb (erenumab) to an anti-CGRP mAb (galcanezumab or fremanezumab). The treatment response to fremanezumab seems to be independent of the prior treatment response to galcanezumab. Our findings suggest that switching to another anti-CGRP mAb can be considered when a particular anti-CGRP mAb is ineffective or intolerable.

Efficacy and safety of eptinezumab 300mg versus 100mg for migraine patients: a meta-analysis of randomized controlled studies

Introduction: Eptinezumab holds important promise in treating migraine patients, but its ideal dose is unknown. This meta-analysis aims to compare the efficacy and safety of eptinezumab 300 mg versus 100 mg for migraine patients.Methods: Several databases including PubMed, Web of science, EBSCO, EMbase and Cochrane library databases have been systematically searched and we included the randomized controlled trials (RCTs) assessing the effect of eptinezumab 300 mg versus 100 mg for migraine patients. This meta-analysis was conducted using the random-effect model.Results: Five RCTs and 1989 patients were included in the meta-analysis. Compared with eptinezumab 100 mg in migraine patients, eptinezumab 300 mg was associated with substantially reduced monthly migraine days (MD=-0.50; 95% CI=-0.56 to -0.44; p < 0.00001), increased 75% responder rate (OR = 1.32; 95% CI = 1.07 to 1.62; p = 0.008) and 50% responder rate (OR = 1.24; 95% CI = 1.04 to 1.48; p = 0.02), but unraveled no remarkable influence on migraine 1 day after dosing (OR = 0.92; 95% CI = 0.72 to 1.18; p = 0.52), adverse events (OR = 1.07; 95% CI = 0.81 to 1.42; p = 0.62) or serious adverse events (OR = 1.60; 95% CI = 0.68 to 3.74; p = 0.40).Conclusions: Eptinezumab 300 mg was superior to eptinezumab 100 mg for the treatment of migraine patients.

A Drug-Drug Interaction Study to Evaluate the Impact of Rimegepant on OCT2- and MATE1-Mediated Transport of Metformin in Healthy Participants

Rimegepant is a calcitonin gene-related peptide receptor antagonist approved for migraine treatment. This phase 1, open-label, single-center, fixed-sequence study evaluated the effect of rimegepant on the pharmacokinetics (PK) of metformin. Twenty-eight healthy participants received metformin 500 mg twice daily from Days 1 to 4 and Days 7 to 10, and once daily on Days 5 and 11. Rimegepant, 75 mg tablet, was administered once daily from Days 9 to 12. At pre-specified time points, plasma metformin concentration, serum glucose levels, and safety and tolerability were evaluated. A 16% increase in the area under the plasma metformin concentration-time curve (AUC) for 1 dosing interval (AUC0-τ,ss), a statistically insignificant increase in maximum and minimum steady-state metformin concentration (Cmax,ss and Cmin,ss), and a decrease in metformin renal clearance were observed on Day 11 following metformin-rimegepant coadministration compared with metformin alone; however, the changes were not clinically relevant. Additionally, coadministration of rimegepant with metformin did not induce clinically meaningful change in the maximum observed glucose concentration (Gmax) or AUCgluc compared with metformin alone. Overall, rimegepant and metformin coadministration did not result in clinically relevant changes in metformin PK, renal clearance, or the antihyperglycemic effects of metformin. Rimegepant is considered safe for use with metformin.

Patient engagement in designing, conducting, and disseminating clinical pain research: IMMPACT recommended considerations

ABSTRACT

In the traditional clinical research model, patients are typically involved only as participants. However, there has been a shift in recent years highlighting the value and contributions that patients bring as members of the research team, across the clinical research lifecycle. It is becoming increasingly evident that to develop research that is both meaningful to people who have the targeted condition and is feasible, there are important benefits of involving patients in the planning, conduct, and dissemination of research from its earliest stages. In fact, research funders and regulatory agencies are now explicitly encouraging, and sometimes requiring, that patients are engaged as partners in research. Although this approach has become commonplace in some fields of clinical research, it remains the exception in clinical pain research. As such, the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials convened a meeting with patient partners and international representatives from academia, patient advocacy groups, government regulatory agencies, research funding organizations, academic journals, and the biopharmaceutical industry to develop consensus recommendations for advancing patient engagement in all stages of clinical pain research in an effective and purposeful manner. This article summarizes the results of this meeting and offers considerations for meaningful and authentic engagement of patient partners in clinical pain research, including recommendations for representation, timing, continuous engagement, measurement, reporting, and research dissemination.

Untangling the mess of CGRP levels as a migraine biomarker: an in-depth literature review and analysis of our experimental experience

BACKGROUND

Calcitonin gene-related peptide (CGRP) is the most promising candidate to become the first migraine biomarker. However, literature shows clashing results and suggests a methodological source for such discrepancies. We aimed to investigate some of these methodological factors to evaluate the actual role of CGRP as biomarker.

METHODS

Previous to the experimental part, we performed a literature review of articles measuring CGRP in migraine patients. Using our 399 bio-bank sera samples, we performed a series of experiments to test the validity of different ELISA kits employed, time of sample processing, long-term storage, sampling in rest or after moderate exercise. Analysis of in-house data was performed to analyse average levels of the peptide and the effect of sex and age.

RESULTS

Literature review shows the high variability in terms of study design, determination methods, results and conclusions obtained by studies including CGRP determinations in migraine patients. CGRP measurements depends on the method and specific kit employed, also on the isoform detected, showing completely different ranges of concentrations. Alpha-CGRP and beta-CGRP had median with IQR levels of 37.5 (28.2-54.4) and 4.6 (2.4-6.4)pg/mL, respectively. CGRP content is preserved in serum within the 24 first hours when samples are stored at 4°C after clotting and immediate centrifugation. Storages at -80°C of more than 6 months result in a decrease in CGRP levels. Moderate exercise prior to blood extraction does not modulate the concentration of the peptide. Age positively correlates with beta-CGRP content and men have higher alpha-CGRP levels than women.

CONCLUSIONS

We present valuable information for CGRP measurements in serum. ELISA kit suitability should be tested prior to the experiments. Alpha and beta-CGRP levels should be analysed separately as they can show different behaviours even within the same condition. Samples can be processed in a 24-h window if they have been kept in 4°C and should not be stored for more than 6 months at -80°C before assayed. Patients do not need to rest before the blood extraction unless they have performed a high-endurance exercise. For comparative studies, sex and age should be accounted for as these parameters can impact CGRP concentrations.

Dynamic fluctuations of salivary CGRP levels during migraine attacks: association with clinical variables and phenotypic characterization

BACKGROUND

Migraine is a complex neurological disorder with significant heterogeneity in its clinical presentation and molecular mechanisms. Calcitonin gene-related peptide (CGRP) has emerged as a key player in migraine pathophysiology, but challenges remain in its utilization as a biomarker. This study aimed to investigate salivary CGRP levels during migraine attacks across the frequency spectrum and explore associations with clinical variables.

METHODS

A prospective longitudinal pilot study was conducted, recruiting migraine patients from an outpatient headache clinic. Salivary CGRP levels were measured at interictal, onset, post-2 h of onset and end-of-attack. Using generalized linear mixed models, we explored the effect of CGRP changes over the attack in presence of depressive symptoms (DS), acute attack treatment, and after three-months of erenumab treatment. Finally, patients were classified and compared according to their CGRP phenotype.

RESULTS

A total of 44 migraine patients were included (90.9% women), with 80 migraine attacks analyzed. Salivary CGRP levels increased at the onset of migraine attacks. We observed statistically significant interactions between DS and both the linear (Est. [SE]: 19.4 [5.8], p = 0.001) and quadratic terms of time (-19.1 [6.0], p = 0.002). Additionally, a significant three-way interaction within the use of acute treated attack (linear-term: -18.5 [6.2], p = 0.005; quadratic-term: 19.2 [6.8], p = 0.005) was also found. Molecular phenotyping revealed that 72.7% (32/44) of patients presented only CGRP-dependent attacks, while 27.3% (12/44) presented non-CGRP-dependent migraine attacks. Patients with only CGRP-dependent attacks were associated with younger age, shorter disease evolution time, a higher proportion of aura, and fewer monthly headache days (p < 0.05). Exploratory analysis of erenumab treatment effects did not result in changes in CGRP levels during migraine attacks.

CONCLUSIONS

Our study underscores the dynamic nature of migraine at a molecular level and emphasizes the importance of integrating clinical variables, such as depressive symptoms, in understanding its pathophysiology. The identification of distinct migraine subtypes based on CGRP dependence suggests potential opportunities for personalized treatment approaches.

Migraine and Its Treatment from the Medicinal Chemistry Perspective

Migraine is a disease of neurovascular origin that affects the quality of life of more than one billion people and ranks sixth among the most common diseases in the world. Migraine is characterized by a moderate or severe recurrent and throbbing headache, accompanied by nausea, vomiting, and photo-phonophobia. It usually starts in adolescence and is twice as common in women as in men. It is classified as with or without aura and has chronic or acute treatment types according to the frequency of occurrence. In acute treatment, analgesics that relieve pain in the fastest way are preferred, while there are different options in chronic treatment. While non-specific methods were used in the treatment of migraine until the 1950s, triptans, ditans, and CGRP-receptor-dependent therapies (monoclonal antibodies and gepants) started to be used in the clinic more recently. In this Review, we focus on the synthesis, side effects, and pharmacological and pharmacokinetic properties of FDA-approved drugs used in acute and preventive-specific treatment of migraine.

Reconceptualizing autonomic function testing in migraine: a systematic review and meta-analysis

BACKGROUND

Autonomic nervous system (ANS) testing has aided in our ability to evaluate autonomic dysfunction in migraine patients. We reviewed the literature in multiple databases which investigate ANS function in migraine patients and healthy subjects.

METHODS

This systematic review and meta-analysis examined the respective deep breathing, Valsalva manoeuvre, orthostatic and isometric challenge results, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analyses of Observational Studies in Epidemiology (MOOSE) statements.

RESULTS

Seven articles met all inclusion criteria. Fixed-effects meta-analysis showed migraine patients (n = 424), collectively, had lower interictal autonomic test results compared with healthy controls (n = 268). In detail, this was true for the standardized mean difference (g) of deep breathing (g= -0.32; 95% confidence interval (CI) -0.48, -0.16), orthostatic challenge (g= -0.28; 95% CI -0.44, -0.13) and isometric challenge (g= -0.55; 95% CI -0.71, -0.39) and for the difference of means (MD) of the Valsalva ratio (MD = -0.17; 95% CI -0.23, -0.10).

CONCLUSIONS

Interictal ANS dysfunction can be identified in migraine patients when compared to healthy controls. These findings indicate the importance to evaluate ANS function in migraine patients - especially, as migraine-specific prophylactic therapies (such as anti-calcitonin gene-related peptide (CGRP) antibodies) may affect the function of the ANS.

Unveiling the therapeutic potential of Dl-3-n-butylphthalide in NTG-induced migraine mouse: activating the Nrf2 pathway to alleviate oxidative stress and neuroinflammation

BACKGROUND

Migraine stands as a prevalent primary headache disorder, with prior research highlighting the significant involvement of oxidative stress and inflammatory pathways in its pathogenesis and chronicity. Existing evidence indicates the capacity of Dl-3-n-butylphthalide (NBP) to mitigate oxidative stress and inflammation, thereby conferring neuroprotective benefits in many central nervous system diseases. However, the specific therapeutic implications of NBP in the context of migraine remain to be elucidated.

METHODS

We established a C57BL/6 mouse model of chronic migraine (CM) using recurrent intraperitoneal injections of nitroglycerin (NTG, 10 mg/kg), and prophylactic treatment was simulated by administering NBP (30 mg/kg, 60 mg/kg, 120 mg/kg) by gavage prior to each NTG injection. Mechanical threshold was assessed using von Frey fibers, and photophobia and anxious behaviours were assessed using a light/dark box and elevated plus maze. Expression of c-Fos, calcitonin gene-related peptide (CGRP), Nucleus factor erythroid 2-related factor 2 (Nrf2) and related pathway proteins in the spinal trigeminal nucleus caudalis (SP5C) were detected by Western blotting (WB) or immunofluorescence (IF). The expression of IL-1β, IL-6, TNF-α, Superoxide dismutase (SOD) and malondialdehyde (MDA) in SP5C and CGRP in plasma were detected by ELISA. A reactive oxygen species (ROS) probe was used to detect the expression of ROS in the SP5C.

RESULTS

At the end of the modelling period, chronic migraine mice showed significantly reduced mechanical nociceptive thresholds, as well as photophobic and anxious behaviours. Pretreatment with NBP attenuated nociceptive sensitization, photophobia, and anxiety in the model mice, reduced expression levels of c-Fos and CGRP in the SP5C and activated Nrf2 and its downstream proteins HO-1 and NQO-1. By measuring the associated cytokines, we also found that NBP reduced levels of oxidative stress and inflammation. Most importantly, the therapeutic effect of NBP was significantly reduced after the administration of ML385 to inhibit Nrf2.

CONCLUSIONS

Our data suggest that NBP may alleviate migraine by activating the Nrf2 pathway to reduce oxidative stress and inflammation in migraine mouse models, confirming that it may be a potential drug for the treatment of migraine.

The transition of medication overuse status by acute medication categories in episodic or chronic migraine patients to non-overuse status after receiving anti-CGRP monoclonal antibodies: a systematic review and meta-analysis of phase 3 randomized control trial

OBJECTIVE

The objective of this systematic review and meta-analysis was to determine whether patients with episodic (EM) or chronic migraine (CM), who were treated with anti-CGRP antibodies, showed a reversal from medication overuse (MO) or medication overuse headache (MOH) status at their baseline to non-overuse status. Furthermore, this study aimed to establish which acute headache medication (AHM) categories responded more effectively to anti-CGRP antibodies.

METHODS

A systematic search was conducted in the PubMed database for relevant studies from January 2013 to September 2023. We included phase three randomized controlled trials to examine the role of anti-CGRP antibodies in patients with EM or CM and their MO status. A meta-analysis was conducted to find the association between anti-CGRP antibodies and the number of EM and CM patients with MO or MOH at baseline that reverted to non-MO status or below the MOH threshold.

RESULTS

The initial search yielded a total of 345 studies. After removing duplicates and screening with inclusion criteria, 5 studies fulfilled our conditions. Each study reviewed the response to changes in the MO status of patients after receiving anti-CGRP antibodies, including eptinezumab, fremanezumab, galcanezumab, and erenumab, compared to placebo. Our study analyzed three AHM categories: triptans, simple analgesics, and multiple drugs. The overall relative risk (RR) was 1.44 (95% CI, 1.31 to 1.59; p < 0.001). The RRs for triptans, simple analgesics, and multi-drug groups were 1.71 (95% CI, 1.53 to 1.91; p < 0.001), 1.10 (95% CI, 0.83 to 1.47; p = 0.5), and 1.29 (95%CI 1.14 to 1.46; p < 0.001) respectively.

CONCLUSION

The meta-analysis has shown that anti-CGRP antibodies were statistically significant in transitioning from MO or MOH status to non-MO status or below the MOH threshold (RR = 1.44) for all included studies and all AHM categories except for simple analgesics. Patients from the triptan group had the highest RR of 1.71 with a p-value < 0.001, while the simple analgesics group had an RR of 1.10, however, with a p-value > 0.05. Interestingly, this analysis can be interpreted as that anti-CGRP antibodies might not be effective in reducing simple analgesics use in EM or CM patients. Further studies are needed to investigate these matters.

Safety and efficacy of atogepant for the preventive treatment of episodic migraine in adults for whom conventional oral preventive treatments have failed (ELEVATE): a randomised, placebo-controlled, phase 3b trial

BACKGROUND

Atogepant, an oral calcitonin gene-related peptide receptor antagonist, has been approved for the preventive treatment of migraine, but its efficacy and safety in people who have been failed by conventional oral preventive migraine treatments has not yet been evaluated in a dedicated clinical trial. The ELEVATE trial evaluated the safety, tolerability, and efficacy of atogepant for the preventive treatment of episodic migraine in participants for whom two to four classes of conventional oral preventive treatments have failed.

METHODS

ELEVATE was a randomised, double-blind, placebo-controlled, parallel-group, phase 3b trial done at 73 sites in Canada, the Czech Republic, Denmark, France, Germany, Hungary, Italy, the Netherlands, Poland, Russia, Spain, the UK, and the USA. Adults (18-80 years) with episodic migraine who had previously been failed by two to four classes of conventional oral treatments for migraine prevention were randomly assigned (1:1) using interactive web response technology to oral atogepant 60 mg once a day or placebo, stratified by baseline monthly migraine days, number of treatment classes participants have been failed by, and region. The primary endpoint was change from baseline in mean monthly migraine days across the 12-week treatment period in the off-treatment hypothetical estimand (OTHE) population, which included participants in the safety population (all participants who received ≥1 dose of study intervention) who had evaluable data available for the baseline period and for one or more of the 4-week post-baseline periods (whether on treatment or off treatment). The primary endpoint was analysed using a mixed model for repeated measures and a fixed-sequence procedure was used to control for multiple comparisons. The trial is registered with ClinicalTrials.gov (NCT04740827) and EudraCT (2019-003448-58), and is completed.

FINDINGS

Between March 5, 2021, and Aug 4, 2022, 540 participants were screened, 315 were randomly assigned, and 313 participants (280 [89%] female, 33 [11%] male, and 300 [96%] White) received at least one dose of study intervention. In the OTHE population, which comprised 309 participants (155 assigned to placebo and 154 to atogepant), least squares mean changes from baseline in monthly migraine days across 12 weeks were -1·9 (SE 0·4) with placebo and -4·2 (0·4) with atogepant (least squares mean difference -2·4, 95% CI -3·2 to -1·5; adjusted p<0·0001). The most common treatment-emergent adverse event with atogepant was constipation in 16 (10%) of 156 participants (vs four [3%] of 157 for placebo). Serious adverse events occurred in four [3%] of 156 participants in the atogepant group vs none in the placebo group, and treatment-emergent adverse events resulting in treatment discontinuation occurred in three [2%] in the atogepant group vs two [1%] in the placebo group.

INTERPRETATION

Atogepant 60 mg once a day was safe, well tolerated, and showed significant and clinically relevant reductions in mean monthly migraine days compared with placebo across 12 weeks in patients with episodic migraine who had previously been failed by two to four classes of conventional oral preventive treatments. Atogepant might be an effective preventive treatment option for patients in this difficult-to-treat population.

FUNDING

Allergan (now AbbVie).

Indomethacin-Responsive Headache Disorders

OBJECTIVE

This article describes the clinical features and treatment of the indomethacin-responsive headache disorders paroxysmal hemicrania and hemicrania continua.

LATEST DEVELOPMENTS

Both paroxysmal hemicrania and hemicrania continua are treated with indomethacin at the lowest clinically useful dose. It has recently become clear that some patients with either condition may respond to treatment with noninvasive vagus nerve stimulation, which can be both indomethacin sparing and, in some cases, headache controlling. Given the lifelong nature of both paroxysmal hemicrania and hemicrania continua, brain imaging with MRI is recommended when the conditions are identified, specifically including pituitary views.

ESSENTIAL POINTS

Paroxysmal hemicrania and hemicrania continua are indomethacin-responsive headache disorders that offer a rewarding and unique opportunity to provide marked clinical improvement when recognized and treated appropriately. These disorders share the final common pathway of the trigeminal-autonomic reflex, with head pain and cranial autonomic features, and are differentiated pathophysiologically by the pattern of brain involvement, which can be seen using functional imaging. They have distinct differential diagnoses to which the clinician needs to remain alert.

Cellular and molecular mechanisms involved in the analgesic effects of botulinum neurotoxin: A literature review

Botulinum neurotoxins (BoNTs), derived from Clostridium botulinum, have been employed to treat a range of central and peripheral neurological disease. Some studies indicate that BoNT may be beneficial for pain conditions as well. It has been hypothesized that BoNTs may exert their analgesic effects by preventing the release of pain-related neurotransmitters and neuroinflammatory agents from sensory nerve endings, suppressing glial activation, and inhibiting the transmission of pain-related receptors to the neuronal cell membrane. In addition, there is evidence to suggest that the central analgesic effects of BoNTs are mediated through their retrograde axonal transport. The purpose of this review is to summarize the experimental evidence of the analgesic functions of BoNTs and discuss the cellular and molecular mechanisms by which they can act on pain conditions. Most of the studies reviewed in this article were conducted using BoNT/A. The PubMed database was searched from 1995 to December 2022 to identify relevant literature.

Activation of the BMP2-SMAD1-CGRP pathway in dorsal root ganglia contributes to bone cancer pain in a rat model

Peripheral nerve remodeling and sensitization are involved in cancer-related bone pain. As a member of the transforming growth factor-β class, bone morphogenetic protein 2 (BMP2) is recognized to have a role in the development of the neurological and skeletal systems. Our previous work showed that BMP2 is critical for bone cancer pain (BCP) sensitization. However, the mechanism remains unknown. In the current study, we demonstrated a substantial increase in BMP2 expression in the dorsal root ganglia (DRG) in a rat model of BCP. Knockdown of BMP2 expression ameliorated BCP in rats. Furthermore, the DRG neurons of rats with BCP expressed higher levels of calcitonin gene-related peptide (CGRP), and BCP was successfully suppressed by intrathecal injection of a CGRP receptor blocker (CGRP8-37). Downregulation of BMP2 expression reduced the expression of CGRP in the DRG of rats with BCP and relieved pain behavior. Moreover, we revealed that upregulation of CGRP expression in the DRG may be induced by activation of the BMPR/Smad1 signaling pathway. These findings suggest that BMP2 contributes to BCP by upregulating CGRP in DRG neurons via activating BMPR/Smad1 signaling pathway and that therapeutic targeting of the BMP2-Smad1-CGRP pathway may ameliorate BCP in the context of advanced cancer.

Healthcare resource utilization and associated costs among patients with migraine in Finland: A retrospective register-based study

Migraine is a common chronic brain disorder, characterized by recurring and often disabling attacks of severe headache, with additional symptoms such as photophobia, phonophobia and nausea. Migraine affects especially the working age population. The objective of this retrospective observational register-based study was to analyze the use of healthcare services and associated costs in Finnish migraine patients. Study was based on aggregate data from January 1st, 2020, to December 31st, 2021, from the Finnish Institute for Health and Welfare's national registries. Patients were grouped into nine patient groups according to medication prescriptions and diagnoses. Healthcare resource utilization in specialty, primary, and occupational healthcare was assessed and analyzed separately for all-cause and migraine related healthcare contacts from a one-year period. The total number of patients was 175 711, and most (45%) of the patients belonged to a group that had used only one triptan. Migraine related total healthcare resource utilization was greater for patients that had used two or more triptans compared to those that had used only one. The patients with three or more preventive medications had the highest total migraine related healthcare resource utilization of the studied patient cohorts. Of the total annual healthcare costs 11.5% (50.6 million €) was associated to be migraine related costs. Total per patient per year healthcare costs were highest with patients that had used three or more preventive medications (5 626 €) and lowest in those with only one triptan (2 257 €). Our findings are in line with the recent European Headache Federation consensus statement regarding the unmet need in patients who have had inadequate response to two or more triptans. When assessing the patient access and cost-effectiveness of novel treatments for the treatment of migraine within different healthcare systems, a holistic analysis of the current disease burden along with potential gains for patients and healthcare service providers are essential information in guiding decision-making.

Vagal sensory pathway for the gut-brain communication

The communication between the gut and brain is crucial for regulating various essential physiological functions, such as energy balance, fluid homeostasis, immune response, and emotion. The vagal sensory pathway plays an indispensable role in connecting the gut to the brain. Recently, our knowledge of the vagal gut-brain axis has significantly advanced through molecular genetic studies, revealing a diverse range of vagal sensory cell types with distinct peripheral innervations, response profiles, and physiological functions. Here, we review the current understanding of how vagal sensory neurons contribute to gut-brain communication. First, we highlight recent transcriptomic and genetic approaches that have characterized different vagal sensory cell types. Then, we focus on discussing how different subtypes encode numerous gut-derived signals and how their activities are translated into physiological and behavioral regulations. The emerging insights into the diverse cell types and functional properties of vagal sensory neurons have paved the way for exciting future directions, which may provide valuable insights into potential therapeutic targets for disorders involving gut-brain communication.

Neuropeptide Calcitonin Gene-Related Peptide Promotes Immune Homeostasis of Bacterial Meningitis by Inducing Major Histocompatibility Complex Class II Ubiquitination

BACKGROUND

Calcitonin gene-related peptide (CGRP), an immunomodulatory neuropeptide, is important for regulating pain transmission, vasodilation, and the inflammatory response. However, the molecular mechanisms of the CGRP-mediated immune response remain unknown.

METHODS

The effects of CGRP on bacterial meningitis (BM) and its underlying mechanisms were investigated in BM mice in vivo and macrophages in vitro.

RESULTS

Peripheral injection of CGRP attenuated cytokine storms and protected mice from fatal pneumococcal meningitis, marked by increased bacterial clearance, improved neuroethology, and reduced mortality. When the underlying mechanisms were investigated, we found that CGRP induces proteasome-dependent degradation of major histocompatibility complex class II (MHC-II) in macrophages and then inhibits CD4+ T-cell activation. MARCH1 was identified as an E3 ligase that can be induced by CGRP engagement and promote K48-linked ubiquitination and degradation of MHC-II in macrophages. These results provide new insights into neuropeptide CGRP-mediated immune regulation mechanisms.

CONCLUSIONS

We conclude that targeting the nervous system and manipulating neuroimmune communication is a promising strategy for treating intracranial infections like BM.

Safety and tolerability of atogepant for the preventive treatment of migraine: a post hoc analysis of pooled data from four clinical trials

BACKGROUND

Conventional, non-specific preventive migraine treatments often demonstrate low rates of treatment persistence due to poor efficacy or tolerability. Effective, well-tolerated preventive treatments are needed to reduce migraine symptoms, improve function, and enhance quality of life. Atogepant is a migraine-specific oral calcitonin gene-related peptide receptor antagonist that is indicated for the preventive treatment of migraine in adults. This analysis evaluated the safety and tolerability profile of atogepant for the preventive treatment of migraine, including adverse events (AEs) of interest, such as constipation, nausea, hepatic safety, weight changes, and cardiac disorders.

METHODS

This post hoc analysis was performed using data pooled from 2 (12-week) randomized, double-blind, placebo-controlled trials (RCTs) and 2 (40- and 52-week) open-label long-term safety (LTS) trials of oral atogepant for episodic migraine (EM).

RESULTS

The safety population included 1550 participants from the pooled RCTs (atogepant, n = 1142; placebo, n = 408) and 1424 participants from the pooled LTS trials (atogepant, n = 1228; standard care [SC], n = 196). In total, 643/1142 (56.3%) atogepant participants and 218/408 (53.4%) placebo participants experienced ≥ 1 treatment-emergent AEs (TEAEs) in the RCTs. In the LTS trials, 792/1228 (64.5%) of atogepant participants and 154/196 (78.6%) of SC participants experienced ≥ 1 TEAEs. The most commonly reported TEAEs (≥ 5%) in participants who received atogepant once daily were upper respiratory tract infection (5.3% in RCTs, 7.7% in LTS trials), constipation (6.1% in RCTs, 5.0% in LTS trials), nausea (6.6% in RCTs, 4.6% in LTS trials), and urinary tract infection (3.4% in RCTs, 5.2% in LTS trials). Additionally, weight loss appeared to be dose- and duration-dependent. Most TEAEs were considered unrelated to study drug and few led to discontinuation.

CONCLUSIONS

Overall, atogepant is safe and well tolerated in pooled RCTs and LTS trials for the preventive treatment of EM in adults.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT02848326 (MD-01), NCT03777059 (ADVANCE), NCT03700320 (study 302), NCT03939312 (study 309).

Nociceptive neurons interact directly with gastric cancer cells via a CGRP/Ramp1 axis to promote tumor progression

Cancer cells have been shown to exploit neurons to modulate their survival and growth, including through establishment of neural circuits within the central nervous system (CNS) 1-3 . Here, we report a distinct pattern of cancer-nerve interactions between the peripheral nervous system (PNS) and gastric cancer (GC). In multiple GC mouse models, nociceptive nerves demonstrated the greatest degree of nerve expansion in an NGF-dependent manner. Neural tracing identified CGRP+ peptidergic neurons as the primary gastric sensory neurons. Three-dimensional co-culture models showed that sensory neurons directly connect with gastric cancer spheroids through synapse-like structures. Chemogenetic activation of sensory neurons induced the release of calcium into the cytoplasm of cancer cells, promoting tumor growth and metastasis. Pharmacological ablation of sensory neurons or treatment with CGRP inhibitors suppressed tumor growth and extended survival. Depolarization of gastric tumor membranes through in vivo optogenetic activation led to enhanced calcium flux in nodose ganglia and CGRP release, defining a cancer cell-peptidergic neuronal circuit. Together, these findings establish the functional connectivity between cancer and sensory neurons, identifying this pathway as a potential therapeutic target.

Targeting the PACAP-38 pathway is an emerging therapeutic strategy for migraine prevention

INTRODUCTION

The pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) has emerged as a key mediator of migraine pathogenesis. PACAP-38 and its receptors are predominantly distributed in arteries, sensory and parasympathetic neurons of the trigeminovascular system. Phase 2 trials have tested human monoclonal antibodies designed to bind and inhibit PACAP-38 and the pituitary adenylate cyclase-activating polypeptide type I (PAC1) receptor for migraine prevention.

AREAS COVERED

This review focuses on the significance of the PACAP-38 pathway as a target in migraine prevention. English peer-reviewed articles were searched in PubMed, Scopus and ClinicalTrials.gov electronic databases.

EXPERT OPINION

A PAC1 receptor monoclonal antibody was not effective for preventing migraine in a proof-of-concept trial, paving the way for alternative strategies to be considered. Lu AG09222 is a humanized monoclonal antibody targeting PACAP-38 that was effective in preventing physiological responses of PACAP38 and reducing monthly migraine days in individuals with migraine. Further studies are necessary to elucidate the clinical utility, long-term safety and cost-effectiveness of therapies targeting the PACAP pathway.