Effects of Anti-Calcitonin Gene-Related Peptide for Migraines: A Systematic Review with Meta-Analysis of Randomized Clinical Trials

Molecular mechanisms of hormones implicated in migraine and the translational implication for transgender patients

Migraine is a primary headache disorder recognized by the World Health Organization as one of the most poorly understood and debilitating neurological conditions impacting global disability. Chronic pain disorders are more frequently diagnosed among cisgender women than men, suggesting that female sex hormones could be responsible for mediating chronic pain, including migraine and/or that androgens can be protective. This review discusses the major gonadal hormones, estrogens, progesterone, and testosterone in the context of molecular mechanisms by which they play a role in migraine pathophysiology. In addition, the literature to date describing roles of minor sex hormones including prolactin, luteinizing hormone, follicular stimulating hormone, and gonadotropin releasing hormone in migraine are presented. Because transgender and gender non-conforming (trans*) individuals are an underserved patient population in which gender-affirming sex hormone replacement therapy (HRT) is often medically necessary to align biological sex with gender identity, results from cisgender patient populations are discussed in the context of these major and minor sex hormones on migraine incidence and management in trans* patients.

Switching of monoclonal antibodies against calcitonin gene-related peptide in chronic migraine in clinical practice: a case series

A multicentre case series of patients with chronic migraine (CM) treated with monoclonal antibodies directed against calcitonin gene-related peptide (CGRP-mAbs) switching were developed. The effectiveness and safety of CGRP-mAbs switching as a preventive treatment for CM in clinical practice were recorded. Effectiveness was measured by ≥50% reduction of monthly migraine days in respect to baseline and reduction in pain intensity. Safety was analysed through adverse events (AEs) and treatment discontinuations. Seven patients were included. The reason for switching was non-response in all cases. Two patients presented a response to the first CGRP-mAb, but the effect was lost after 3 months. The remaining five patients were non-responders. Response to the second CGRP-mAb was observed in three patients, one of them for >3 months. Less than half of the patients previously treated with a CGRP-mAb responded to switching with a second CGRP-mAb. AEs were rare, with no treatment discontinuations.

A head-to-head observational cohort study on the efficacy and safety of monoclonal antibodies against calcitonin gene-related peptide for chronic and episodic migraine

OBJECTIVE

To compare the effectiveness and safety of galcanezumab, fremanezumab, and erenumab for the treatment of chronic and episodic migraine, through real-world data.

BACKGROUND

Monoclonal antibodies (mAbs) targeting the calcitonin gene-related peptide (CGRP) pathway have been tested extensively in several clinical trials for both episodic and chronic migraine, showing high effectiveness, safety, and tolerability; however, there are no prospective real-world studies intending to compare their efficacy and safety.

METHODS

This is a prospective observational cohort study comparing the effectiveness and safety profiles of galcanezumab, fremanezumab, and erenumab for the treatment of chronic and episodic migraine. We enrolled 140 patients at the Headache Centre of University Federico II of Naples, with a history of multiple failed treatments with validated migraine preventatives. Framenezumab, erenumab, or galcanezumab were administered for 12 months. The mean monthly days with headache, Migraine Disability Assessment (MIDAS) score, and adverse events were evaluated during the run-in period and every 3 months by reviewing standardized paper patient headache diaries.

RESULTS

We found a mean reduction of migraine monthly days from baseline of -12.0 (-9.8, -14.1) in the galcanezumab group, -12.3 (-10.2, -14.3) in the fremanezumab group, and -10.8 (-8.5, -13.1) in the erenumab group (for all, p < 0.001). We found a mean reduction of MIDAS score of -32.6 (-26.6, -38.5) in the galcanezumab group, -33.4 (-28.0, -38.9) in the fremanezumab group, and -29.2 (-23.0, -35.4) in the erenumab group (for all, p < 0.001). We found no significant differences between mAbs in the reduction of mean monthly days with headache and MIDAS score. We found a more rapid effect of galcanezumab and erenumab compared to fremanezumab in medication overuse headache patients after 3 months of treatment (-10.8 and -11.1 vs. -4.0 days; p = 0.029).

CONCLUSION

Our results confirm the therapeutic benefits of anti-CGRP mAbs. There is no evidence that suggests that one antibody may be superior to the others in terms of effectiveness, both in chronic and episodic patients.

Oral Health-Related Quality of Life among Chinese Chronic Orofacial Pain Patients with Psychological Health Problems: A Moderated Mediation Model

Psychological therapies are important for comprehensive chronic orofacial pain (COFP) treatment. This study is to validate the effects of psychological factors on oral health-related quality of life (OHRQoL) among COFP patients in China. Pain catastrophizing, which is a subjective cognitive emotion used to manage the psychological aspects of pain among COFP patients, was examined in relation to COFP severity and OHRQoL. All 479 participants were recruited in Changsha, Hunan Province, China. Cronbach's alpha coefficients (0.868-0.960), composite reliability scores (0.924-0.969), and average variance extracted from each construct (0.555-0.753) all indicated a good model fit. Pearson's correlation analysis showed that age and education status have a positive correlation with COFP severity, pain catastrophizing, and anxiety. COFP severity was related to anxiety, depression, and COFP-OHRQoL. Pain catastrophizing was related to employment status. Anxiety and depression symptoms indirectly mediated the correlation between COFP severity and COFP-OHRQoL. As a second-stage moderator, pain catastrophizing moderated the mediating effects of anxiety symptoms and depression symptoms. Our findings suggest that anxiety, depression, and pain catastrophizing should be evaluated jointly to improve COFP-OHRQoL among COFP patients. This evidence will help therapists to comprehensively treat patients for the best treatment effect.

Treatment of resistant chronic migraine with anti-CGRP monoclonal antibodies: a systematic review

Background

Resistant chronic migraine is a highly disabling condition which is very difficult to treat. The majority of the treatments for migraine prophylaxis are nonspecific and present weak safety profiles, leading to low adherence and discontinuation. Currently, monoclonal antibodies (mAb) targeting the trigeminal sensory neuropeptide, calcitonin gene-related peptide (CGRP), are available for migraine prophylaxis being the first drugs developed specifically to target migraine pathogenesis. The main objective of the current work is to carry out a systematic review of randomised controlled trials that specifically analyse the effectivity and safety of anti-CGRP mAb, comparatively to placebo, in patients with resistant chronic migraine and possibly fill the literature gap or be a source of information to health professionals. Additionally the current knowledge on migraine, particularly resistant chronic migraine, was revisited and summarised.

Methods

Literature search was carried out on MEDLINE, Scopus, Science Direct and ClinicalTrials.gov database, from inception to December 2021. Articles were selected according to prespecified criteria of inclusion and exclusion. Efficacy and safety outcomes included were: change from baseline in monthly migraine days (MMD); ≥50% reduction of MMD values from baseline; change from baseline in monthly acute migraine-specific medication days (MAMD); Migraine-specific Quality of Life Questionnaire (MSQ); and registered adverse events. Additionally, we used the Cochrane risk of bias tool (RoB 2) to assess the risk of bias of the included studies.

Results

Four studies were included in this systematic review, involving 2811 resistant chronic migraine patients, 667 in a study using erenumab, 838 in a study using fremanezumab and 1306 in two studies using galcanezumab. When compared to placebo, all investigated anti-CGRP mAb and respective doses demonstrate effectiveness in decreasing MMD, reducing acute medication use and improving the MSQ scores, including, sometimes, reversion of chronic to episodic migraine (efficacy outcomes). Regarding the safety outcomes, the number and type of adverse events did not differ between anti-CGRP mAb-treated and placebo groups.

Conclusions

Anti-CGRP or anti-CGRP receptor monoclonal antibodies are a promising preventive migraine therapy which can be particularly useful for resistant chronic migraine patients.

Direct cost and healthcare resource utilization of patients with migraine before treatment initiation with calcitonin gene-related peptide monoclonal antibodies by the number of prior preventive migraine medication classes

OBJECTIVE

This study compared all-cause direct cost and healthcare resource utilization (HCRU) among preventive migraine medication (PMM)-naïve patients and patients with up to 3 PMM category switches before initiating calcitonin gene-related peptide (CGRP) monoclonal antibodies (mAbs).

METHODS

This was a retrospective analysis of the IBM Marketscan database. Patients who initiated injectable CGRP mAbs between May 2018 and December 2019 (index period) were included in 4 groups based on the number of prior non-CGRP PMM classes used during the 24-month pre-index period: P0 = none; P1 = one; P2 = two; P3 ≥ three. All-cause direct cost and HCRU for groups were compared without adjustment and after generalized propensity score (GPS) matching.

RESULTS

Of the 23,288 patients included (mean age ± standard deviation [SD] 45.4 ± 12.0 years), 85.6% were females, and the mean Charlson Comorbidity Index was 0.69 ± 1.2. P3 group had the highest average annual unadjusted total healthcare costs per patient ($50,274±$76,629); the highest costs attributed to procedure/imaging-related expenses ($20,105±$36,401) and pharmacy ($11,633±$29,763). P0 group had the lowest cost ($25,288±$41,427). Pairwise comparison of GPS matched costs showed significantly greater average annual direct costs per patient in the P3 group vs. P0 (p = .003), P1 (p = .014), and P2 (p = .021) groups. GPS matched HCRU also increased with the number of prior PMM classes used. Anti-epileptics (48.9%) were the most commonly used PMM class, with triptans (75.2%) being the most common acute medication class.

CONCLUSIONS

Total direct healthcare cost and HCRU increased significantly with increasing use of PMM classes with the greatest cost difference existing between the P0 and the P3 groups.

Off-label Uses of Selective Serotonin Reuptake Inhibitors (SSRIs)

Psychiatric drugs have primacy for off-label prescribing. Among those, selective serotonin reuptake inhibitors (SSRIs) are highly versatile and, therefore, widely prescribed. Moreover, they are commonly considered as having a better safety profile compared to other antidepressants. Thus, when it comes to off-label prescribing, SSRIs rank among the top positions. In this review, we present the state of the art of off-label applications of selective serotonin reuptake inhibitors, ranging from migraine prophylaxis to SARS-CoV-2 antiviral properties. Research on SSRIs provided significant evidence in the treatment of premature ejaculation, both with the on-label dapoxetine 30 mg and the off-label paroxetine 20 mg. However, other than a serotoninergic syndrome, serious conditions like increased bleeding rates, hyponatremia, hepatoxicity, and post-SSRIs sexual dysfunctions, are consistently more prominent when using such compounds. These insidious side effects might be frequently underestimated during common clinical practice, especially by nonpsychiatrists. Thus, some points must be addressed when using SSRIs. Among these, a psychiatric evaluation before every administration that falls outside the regulatory agencies-approved guidelines has to be considered mandatory. For these reasons, we aim with the present article to identify the risks of inappropriate uses and to advocate the need to actively boost research encouraging future clinical trials on this topic.

Quality of Life Related to Functional Disability in Migraine Patients: A Systematic Review and Network Meta-analysis

OBJECTIVE

The aim of this study was to conduct a systematic review and network meta-analysis of all randomized trials investigating effect of anti-calcitonin gene-related peptide monoclonal antibodies on disability related to migraine in adult patients.

MATERIALS AND METHODS

Medline, Embase, and Cochrane Central Register of Controlled Trials searched from inception to July 2020 with an additional review of clinical trial registries. Disability evaluated using change in patient reported Migraine Disability Assessment scores from baseline were considered for the final analysis. The network meta-analysis was conducted in Bayesian framework using OpenBUGS and R, with the random effects model selected to allow for apparent heterogeneity between studies in the treatment comparison effects.

RESULTS

Overall 41 studies (7095 migraineurs in 9 randomized trials) were included with treatment course of at least 12 weeks. Subcutaneous injections of fremanezumab 675+225+225 mg QM and 225+225+225 mg QM were more effective in reducing disability in chronic and episodic migraine patients, respectively, with higher median difference in Migraine Disability Assessment score from baseline compared with other treatments including erenumab (70 mg QM; 140 mg QM), galcanezumab (120 mg QM; 240 mg QM), and low doses of fremanezumab (225 mg single dose; 675 mg single dose).

DISCUSSION

For short-term prevention of migraine, fremanezumab demonstrated slightly better improvement in disability compared with other anti-calcitonin gene-related peptide monoclonal antibodies in adult patients with migraine.

Efficacy and safety of anti-calcitonin gene-related peptide monoclonal antibodies for treatment of chronic migraine: A systematic review and network meta-analysis

BACKGROUND & OBJECTIVE

To conduct a systematic review and network meta-analysis of all randomized trials investigating effects of anti-calcitonin gene related peptide monoclonal antibodies (anti-CGRP mAbs) on adult patients with chronic migraine.

METHODS

MEDLINE, Embase and Cochrane Central Register of Controlled Trials searched from inception to July 2020; and clinical trial registries. The network meta-analysis was conducted in Bayesian framework using OpenBUGS and R, with the random effects model selected to allow for apparent heterogeneity between studies in the treatment comparison effects.

RESULTS

Overall 38 studies (5164 chronic migraineurs in seven randomized trials) were included with treatment course of at least 12 weeks. Fremanezumab 675 + 225 + 225 mg QM (SC) injections were numerically more effective in lowering migraine days with lower MDs compared to eptinezumab 10 mg (IV) (MD: -1.52, 95% CrIs: -4.24, 0.99), eptinezumab 30 mg (IV) (MD: -0.33, 95% CrIs: -3.02, 2.16), eptinezumab 100 mg (IV) (MD: -0.59, 95% CrIs: -2.80, 1.42), eptinezumab 300 mg (IV) (MD: -0.02, 95% CrIs: -2.29, 1.98), erenumab 70 mg QM (SC) (MD: -0.17, 95% CrIs: -2.84, 2.25), erenumab 140 mg QM (SC) (MD: -0.18, 95% CrIs: -2.87, 2.26), fremanezumab 675 mg (SC) (MD: -0.30, 95% CrIs: -1.81, 1.14), galcanezumab 120 mg QM (SC) (MD: -0.71, 95% CrIs: -3.44, 1.55) and galcanezumab 240 mg QM (SC) (MD: -0.58, 95% CrIs: -3.09, 1.89), however the results were non-significant. Similarly, the anti-CGRP mAbs were also observed to have comparable safety and immunogenicity with no significant differences.

CONCLUSIONS

Although all doses of anti-CGRP mAbs have comparable efficacy, safety and tolerability based on uncertainties in indirect comparisons for all outcomes, the calculated effect estimates numerically favored high doses of subcutaneous fremanezumab and intravenous eptinezumab as the effective therapy with acceptable safety and tolerability for short term prevention of chronic migraine.

Could erectile dysfunction be a side effect of CGRP inhibition? A case report

Background

Recently, antimigraine drugs targeting the calcitonin gene-related peptide pathway have been approved for clinical use as preventive migraine medication.

Case report

We present a case of a 54-year-old male migraine patient, who reported erectile dysfunction as a possible side effect of treatment with galcanezumab, a monoclonal antibody targeting calcitonin gene-related peptide. His potency recovered after treatment discontinuation.

Discussion

As calcitonin gene-related peptide is involved in mammalian penile erection, erectile dysfunction is a conceivable side effect associated with calcitonin gene-related peptide inhibition. Postmarketing surveillance will elucidate the actual incidence of erectile dysfunction in patients using these new antimigraine drugs, and determine whether a causal relationship between calcitonin gene-related peptide inhibition and erectile dysfunction exists. This would be relevant not only because of the direct sexual consequences of erectile dysfunction, but also considering the potential cardiovascular consequences of calcitonin gene-related peptide (receptor) blockade and the association of both migraine and erectile dysfunction with cardiovascular disease.

Conclusion

Erectile dysfunction might be an overlooked, but reversible side effect in male migraine patients using monoclonal antibodies that inhibit the calcitonin gene-related peptide pathway, including galcanezumab. This paper may raise clinical awareness and suggest that this potential side effect needs to be studied further.

Long-term (48 weeks) effectiveness, safety, and tolerability of erenumab in the prevention of high-frequency episodic and chronic migraine in a real world: Results of the EARLY 2 study

OBJECTIVE

To evaluate the long-term effectiveness, safety, and tolerability of erenumab in a real-world migraine population, looking for putative predictors of responsiveness.

BACKGROUND

Erenumab proved to be effective, safe, and well tolerated in the prevention of episodic migraine (EM) and chronic migraine (CM) in long-term extension studies of double-blind, placebo-controlled trials in patients with no more than two (EM) or three (CM) prior preventive treatment failures.

METHODS

A 48-week, multicenter, longitudinal cohort real-life study was conducted at 15 headache centers across eight Italian regions between December 20, 2018 and July 31, 2020. We considered all consecutive patients with high-frequency episodic migraine (HFEM) or CM aged 18-65 years. Each patient was treated with erenumab 70 mg, administered monthly. The dose was switched to 140 mg in nonresponders and in responders who had become nonresponders for at least 4 weeks. Change in monthly migraine days (MMDs) or monthly headache days (MHDs) at Weeks 45-48 compared with baseline was the primary efficacy endpoint. Secondary endpoints encompassed variation in monthly analgesic intake, achievement of a ≥50%, ≥75%, or 100% reduction in migraine or headache days, and any change in the Visual Analogue Scale (VAS) and Headache Impact Test-6 scores (HIT-6) during the same time interval.

RESULTS

A total of 242 patients with migraine received at least one dose of erenumab 70 mg and were considered for safety analysis, whereas 221 received a monthly erenumab dose for ≥48 weeks and were included in the effectiveness and safety analysis set. All patients had previously been treated unsuccessfully with ≥3 migraine-preventive medication classes. From baseline to Weeks 45-48, erenumab treatment reduced MMD by 4.3 ± 5.3 (mean ± SD) in patients with HFEM, and MHD by 12.8 ± 8.9 (mean ± SD) in subjects with CM. VAS and HIT-6 scores were decreased by 1.8 ± 1.9 (mean ± SD) and 12.3 ± 11 (mean ± SD) in HFEM, and by 3.0 ± 2.2 (mean ± SD) and 13.1 ± 11.2 (mean ± SD) in CM. Median monthly analgesic intake passed from 11.0 (interquartile range [IQR] 10.0-13.0) to 5 (IQR 2.0-8.0) in HFEM and from 20.0 (IQR 15.0-30.0) to 6.0 (IQR 3.8-10.0) in CM. The ≥50% responders were 56.1% (32/57) in HFEM and 75.6% (124/164) in CM; ≥75% responders were 31.6% (18/57) and 44.5% (73/164); and 100% responders were 8.8% (5/57) and 1.2% (2/164), respectively. At Week 48, 83.6% (137/164) of patients with CM had reverted to EM. Erenumab was safe and well tolerated. Responsiveness to erenumab was positively associated with cutaneous allodynia (OR: 5.44, 95% CI: 1.52-19.41; p = 0.009) in HFEM. In patients with CM, ≥50% responsiveness was positively associated with male sex (OR: 2.99, 95% CI: 1.03-8.7; p = 0.044) and baseline migraine frequency (OR: 1.12, 95% CI: 1.05-1.20; p = 0.001) and negatively associated with psychiatric comorbidities (OR: 0.37, 95% CI: 0.15-0.87; p = 0.023) and prior treatment failures (OR: 0.77, 95% CI: 0.64-0.92; p = 0.004).

CONCLUSIONS

Long-term (48-week) erenumab treatment provides sustained effectiveness, safety, and tolerability in real-life patients with HFEM or CM with ≥3 prior preventive treatment failures. The dose of 140 mg was required in most patients along the study and should be taken into consideration as the starting dose. Allodynia (in HFEM), male sex, and baseline migraine frequency (in CM) might represent positive responsiveness predictors. Conversely, psychiatric comorbidities and multiple prior preventive treatment failures could be negative predictors in patients with CM.

Narrative Medicine to integrate patients', caregivers' and clinicians' migraine experiences: the DRONE multicentre project

Background

Although migraine is widespread and disabling, stigmatisation and poor awareness of the condition still represent barriers to effective care; furthermore, research on migraine individual and social impact must be enhanced to unveil neglected issues, such as caregiving burden. The project investigated the migraine illness experience through Narrative Medicine (NM) to understand daily life, needs and personal resources of migraneurs, their caregivers and clinicians, and to provide insights for clinical practice.

Methods

The project involved 13 Italian headache centres and targeted migraneurs, their caregivers and migraine specialists at these centres. Written narratives, composed by a sociodemographic survey and illness plot or parallel chart, were collected through the project’s webpage. Illness plots and parallel charts employed open words to encourage participants’ expression. Narratives were analysed through Nvivo software, interpretive coding and NM classifications.

Results

One hundred and seven narratives were collected from patients and 26 from caregivers, as well as 45 parallel charts from clinicians. The analysis revealed migraine perception in social, domestic and work life within the care pathway evolution and a bond between chaos narratives and day loss due to migraine; furthermore, narratives suggested the extent of the caregiving burden and a risk of underestimation of migraine burden in patients’ and caregivers’ life.

Conclusion

The project represents the first investigation on migraine illness experience through NM simultaneously considering migraneurs’, caregivers’ and clinicians’ perspectives. Comparing narratives and parallel charts allowed to obtain suggestions for clinical practice, while NM emerged as able to foster the pursuing of migraine knowledge and awareness.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-021-05227-w.

CGRP monoclonal antibody prevents the loss of diffuse noxious inhibitory controls (DNIC) in a mouse model of post-traumatic headache

AIM

Determine the role of calcitonin-gene related peptide in promoting post-traumatic headache and dysregulation of central pain modulation induced by mild traumatic brain injury in mice.

METHODS

Mild traumatic brain injury was induced in lightly anesthetized male C57BL/6J mice by a weight drop onto a closed and unfixed skull, which allowed free head rotation after the impact. We first determined possible alterations in the diffuse noxious inhibitory controls, a measure of net descending pain inhibition called conditioned pain modulation in humans at day 2 following mild traumatic brain injury. Diffuse noxious inhibitory control was assessed as the latency to a thermally induced tail-flick that served as the test stimulus in the presence of right forepaw capsaicin injection that provided the conditioning stimulus. Post-traumatic headache-like behaviors were assessed by the development of cutaneous allodynia in the periorbital and hindpaw regions after mild traumatic brain injury. We then determined if intraperitoneal fremanezumab, an anti-calcitonin-gene related peptide monoclonal antibody or vehicle administered 2 h after sham or mild traumatic brain injury induction could alter cutaneous allodynia or diffuse noxious inhibitory control responses on day 2 post mild traumatic brain injury.

RESULTS

In naïve and sham mice, capsaicin injection into the forepaw elevated the latency to tail-flick, reflecting the antinociceptive diffuse noxious inhibitory control response. Periorbital and hindpaw cutaneous allodynia, as well as a loss of diffuse noxious inhibitory control, was observed in mice 2 days after mild traumatic brain injury. Systemic treatment with fremanezumab blocked mild traumatic brain injury-induced cutaneous allodynia and prevented the loss of diffuse noxious inhibitory controls in mice subjected to a mild traumatic brain injury.

INTERPRETATION

Sequestration of calcitonin-gene related peptide in the initial stages following mild traumatic brain injury blocked the acute allodynia that may reflect mild traumatic brain injury-related post-traumatic headache and, additionally, prevented the loss of net descending inhibition within central pain modulation pathways. As loss of conditioned pain modulation has been linked to multiple persistent pain conditions, dysregulation of descending modulatory pathways may contribute to the persistence of post-traumatic headache. Additionally, evaluation of the conditioned pain modulation/diffuse noxious inhibitory controls response may serve as a biomarker of vulnerability for chronic/persistent pain. These findings suggest that early anti-calcitonin-gene related peptide intervention has the potential to be effective both for the treatment of mild traumatic brain injury-induced post-traumatic headache, as well as inhibiting mechanisms that may promote post-traumatic headache persistence.

Anti-CGRP monoclonal antibodies for migraine prevention: A systematic review and likelihood to help or harm analysis

INTRODUCTION AND OBJECTIVE

Monoclonal antibodies targeting the calcitonin gene-related peptide pathway (anti-CGRP mAbs) have shown promising efficacy in randomised clinical trials for the prevention of episodic and chronic migraine, but no head-to-head comparisons with established treatments are available. We aimed to examine absolute differences in benefit-risk ratios between anti-CGRP mAbs, topiramate and propranolol for the prevention of episodic migraine and between anti-CGRP mAbs, topiramate and onabotulinumtoxinA for the prevention of chronic migraine using a likelihood to help versus harm analysis.

METHODS

The number of patients needed to be treated for a patient to achieve ≥ 50% reduction in migraine days (NNTB_50%) was used as an effect size metric of efficacy. The number of patients needed to be treated for a patient to experience an adverse event that led to treatment discontinuation (NNTH_D-AE) was used as a measure of risk. Likelihood to help versus harm values - which are the ratios of NNTH:NNTB - were calculated using data from phase 3 randomised clinical trials.

RESULTS

All agents tested were more likely to be beneficial than harmful (likelihood to help versus harm > 1) with the exception of topiramate at 200 mg per day for the prevention of episodic migraine. Anti-CGRP mAbs in all tested doses had higher LHH values than propranolol or topiramate for episodic migraine and onabotulinumtoxinA or topiramate for chronic migraine prevention. Fremanezumab had the highest LHH ratio in episodic migraine and galcanezumab in chronic migraine.

CONCLUSION

This analysis showed that anti-CGRP mAbs exhibit a more favourable benefit-risk ratio than established treatments for episodic and chronic migraine. Head-to-head studies are needed to confirm these results.

Indirect Comparison of Topiramate and Monoclonal Antibodies Against CGRP or Its Receptor for the Prophylaxis of Episodic Migraine: A Systematic Review with Meta-Analysis

BACKGROUND

Head-to-head comparator trials between first-line oral migraine preventatives and the new monoclonal antibodies (mAbs) blocking the calcitonin gene-related peptide (CGRP) pathway have not been published to date.

OBJECTIVES

This study aimed to indirectly compare the clinical efficacy and safety of mAbs against CGRP or its receptor (CGRPR) and topiramate in episodic migraine prophylaxis using meta-analysis.

METHODS

We included controlled trials testing efficacy and safety of erenumab, galcanezumab, fremanezumab, eptinezumab, and topiramate in adults diagnosed with episodic migraine. We searched PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov from January 2000 to November 2020. We used the Risk of Bias 2 (RoB2) tool to assess the risk of bias and report pooled mean effects (mean difference and risk ratio) as estimated in a random effect model. For efficacy analysis, we determined the reduction of monthly migraine days (MMDs), reduction of days with acute medication (AMDs), and 50% responder rates (50% RR). For safety, we determined adverse events (AEs) occurring in ≥ 2% of study participants and the number of patients who discontinue treatment due to AEs (DAEs). The number needed to treat (NNT) and to harm (NNH) were estimated as well as the likelihood to help or harm (LLH).

RESULTS

We included 13 trials involving 7557 patients: three trials with erenumab, two trials with galcanezumab, two trials with fremanezumab, one trial with eptinezumab, and five trials with topiramate, for the prophylaxis of episodic migraine in adults. The placebo-subtracted reduction (pooled mean difference) of MMDs were - 1.55 (95% CI - 1.86 to - 1.24; active drug n = 3326 vs placebo n = 2219, 8 studies) for the CGRP(R) mAb and - 1.11 (95% CI - 1.62 to - 0.59; active drug n = 1032 vs placebo n = 543, 4 studies) for topiramate (p for subgroup difference = 0.15). 'Cognitive' and 'sensory & pain'-related adverse events occurred more often in patients treated with topiramate compared with those treated with a CGRP(R) mAb (p for subgroup difference 0.03 and < 0.001, respectively). Based on the 50% RR and DAE, the NNT, NNH, and LHH for the CGRP(R) mAbs were 6, 130, and 24.3:1, respectively. For topiramate, these values were 7, 9, and 1.8:1, respectively.

CONCLUSION

The efficacy of CGRP(R) mAbs to reduce migraine days does not differ from topiramate. However, the safety profile is in favor of the CGRP(R) mAbs, with a higher likelihood to help than to harm compared with topiramate. The diversity of endpoint determination and the heterogeneity between studies for some endpoints cause some limitations for this study.

Tolerability and Optimal Therapeutic Dosage of Clomipramine for Premature Ejaculation: A Systematic Review and Meta-Analysis

INTRODUCTION

Clomipramine is effective in treating premature ejaculation, a common form of male sexual dysfunction that affects individual's mental health and quality of life, but its optimal dosage remains controversial.

AIM

In this systematic review and meta-analysis, we aimed to evaluate the efficacy, safety, and optimal dose of clomipramine for treating premature ejaculation among men.

METHODS

Eligible studies of PubMed, Embase, and Web of Science were identified from the date of inception to June 21, 2020. We conducted the study according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data of the study characteristics, intravaginal latency ejaculatory time (IELT), adverse events, success rate, and satisfaction rate of clomipramine vs placebo were extracted and analyzed. The risk ratio and mean difference were used for quantitatively analyzing binary outcomes and continuous outcomes. The standardized mean difference was applied to the outcome of satisfaction rate. The Mantel-Haenszel method was used for meta-analysis under random-effects model. To assess dose effect of clomipramine, a meta-regression analysis was performed.

MAIN OUTCOME MEASURES

The primary outcomes were the IELT and adverse events, and the secondary outcomes were the success rate and satisfaction rate of clomipramine treatment relative to the placebo.

RESULTS

A total 14 randomized controlled trials with 710 patients were included for quantitative analysis. Clomipramine significantly increased the IELT compared with the placebo (mean difference: 1.47, 95% CI: 0.73-2.21). However, clomipramine was associated with higher risks of overall adverse events and adverse events in the nervous and respiratory systems. Significant dosage effects on the IELT (estimate: 0.0637, 95% CI: 0.0074-0.12) and a slightly increasing slope on adverse events were revealed.

CONCLUSION

Clomipramine increased the IELT and yielded greater satisfaction than the placebo, and the higher dose results in a superior IELT without leading to higher risk of adverse events under a dosage of 50-mg clomipramine. Wu P-C, Hung C-S, Kang Y-N, et al. Tolerability and Optimal Therapeutic Dosage of Clomipramine for Premature Ejaculation: A Systematic Review and Meta-Analysis. Sex Med 2021;9:100283.

Characterization and preclinical evaluation of a protease activated receptor 2 (PAR2) monoclonal antibody as a preventive therapy for migraine

AIM

Migraine pain is thought to result from activation of meningeal nociceptors that might involve dural mast cell degranulation and release of proteases and pronociceptive mediators. Tryptase, the most abundant dural mast cell protease, has been demonstrated to stimulate dural mast cells, as well as trigeminal nociceptors by activating the protease activated receptor 2. Mast cell or neuronal protease activated receptors 2 may therefore represent a novel target for migraine treatment. In this study, we characterized and evaluated a novel protease activated receptor 2 monoclonal antibody as a preventive anti-migraine pain therapy in preclinical models.

METHODS

Flow cytometry, immunocytochemistry, calcium imaging, Homogeneous Time Resolved Technology (HTRF) epitope competition assay and serum pharmacokinetic (PK) assay in rats were performed to confirm the activity, specificity and in vivo stability of PAR650097, a novel anti- protease activated receptor 2 monoclonal antibody. In vivo assessment was performed in female C57BL/6J mice by evaluation of PAR650097 in preventing cutaneous allodynia elicited by (a) supradural injection of the protease activated receptor 2 agonist, Ser-Leu-Ile-Gly-Arg-Leu-amide trifluoroacetate (SLIGRL), or calcitonin gene-related (CGRP) peptide, and (b) induction of latent sensitization by priming with three daily episodes of restraint stress followed by challenge with a subthreshold inhalational exposure to umbellulone (UMB), a transient receptor potential ankyrin 1 (TRPA1) agonist. PAR650097 was administered as a pretreatment prior to the first restraint stress, umbellulone exposure, SLIGRL or calcitonin gene-related peptide injection. Additionally, fremanezumab, a calcitonin gene-related peptide antibody was administered as pre-treatment prior to supradural administration of calcitonin gene-related peptide or SLIGRL.

RESULTS

In vitro, PAR650097 demonstrated rapid interaction with protease activated receptor 2, enabling it to fully inhibit protease-induced protease activated receptor 2 activation, in human and mouse cells, with high potency. Furthermore, PAR650097 was highly selective for protease activated receptor 2, demonstrating no affinity for protease activated receptor 1 protein and no functional effect on the activation of cellular protease activated receptor 1 with thrombin. In addition, PAR650097 had an acceptable PK profile, compatible with testing the effects of selective protease activated receptor 2 inhibition in vivo. In vivo, PAR650097 blocked cutaneous allodynia induced by either supradural SLIGRL or calcitonin gene-related peptide. Fremanezumab abolished cutaneous allodynia induced by supradural CGRP, and partially attenuated cutaneous allodynia induced by SLIGRL. Administration of PAR650097, before the first restraint stress episode, did not prevent the acute stress-induced cutaneous allodynia or restraint stress priming revealed by cutaneous allodynia induced by inhalational umbellulone. In contrast, PAR650097 prevented expression of cutaneous allodynia when given before the umbellulone challenge in restraint stress-primed animals.

CONCLUSION

PAR650097 specifically inhibits endogenously expressed protease activated receptor 2 in human and mouse cells with high potency. This antibody has an acceptable PK profile in rodents and effectively blocked SLIGR-induced cutaneous allodynia. PAR650097 additionally prevented cutaneous allodynia induced by supradural calcitonin gene-related peptide, indicating that the protease activated receptor 2 receptor is a downstream consequence of calcitonin gene-related peptide actions. Fremanezumab effectively blocked calcitonin gene-related peptide-induced cutaneous allodynia and only partially reduced cutaneous allodynia induced by a protease activated receptor 2 activator, suggesting both calcitonin gene-related peptide-dependent and -independent mechanisms in promoting migraine pain. While PAR650097 did not prevent stress-induced cutaneous allodynia or priming, it effectively prevented cutaneous allodynia induced by a TRPA1 agonist in animals with latent sensitization. Activation of protease activated receptor 2, therefore, contributes to both calcitonin gene-related peptide-dependent and -independent mechanisms in promoting migraine-like pain. Therapeutic targeting of protease activated receptor 2 receptors may represent an anti-migraine pain strategy with a potentially broad efficacy profile.

Optimal treatment strategy of fremanezumab in migraine prevention: a systematic review with network meta-analysis of randomized clinical trials

Identifying the optimal fremanezumab treatment strategy is crucial in treating patients with migraines. The optimal strategy was investigated by assessing the cumulative 50% reduction rate (50%CRR), cumulative 75% reduction rate (75%CRR), reduction in the number of migraine days, treatment-related adverse events, and serious adverse events in patients treated with fremanezumab 225 mg monthly (225 mg), 675 mg monthly (675 mg), 900 mg monthly (900 mg), a single high dose of 675 mg (S675mg), 675 mg at baseline with 225 mg monthly (675/225 mg), and placebo. Biomedical databases were searched for randomized controlled trials on this topic, and data were individually extracted. Risk ratios and mean differences were used to present the pooled results. The surface under the cumulative ranking curve (SUCRA) was used to determine the effects of the medication strategies of fremanezumab. Five trials (n = 3404) were used to form a six-node network meta-analysis. All fremanezumab medication strategies displayed significantly higher cumulative 50% reduction rates than the placebo. The SUCRA revealed that treatment with 675 mg yielded the highest 50%CRR value (mean rank = 2.5). S675 mg was the only treatment with significantly higher 75%CRR reduction rate than placebo, whereas the SUCRA for 225 mg displayed the highest mean rank (2.2). Moreover, 225 mg (mean rank = 2.2) and S675 mg (mean rank = 2.2) presented lower probabilities of serious adverse events. Collectively, S675mg and 225 mg exhibited the optimal balance between efficacy and safety within three months. Long-term efficacy and safety remain unclear, and future studies should further evaluate the long-term outcomes.

A novel, injury-free rodent model of vulnerability for assessment of acute and preventive therapies reveals temporal contributions of CGRP-receptor activation in migraine-like pain

AIM

Development and characterization of a novel injury-free preclinical model of migraine-like pain allowing mechanistic assessment of both acute and preventive treatments.

METHODS

A "two-hit" hyperalgesic priming strategy was used to induce vulnerability to a normally subthreshold challenge with umbellulone, a transient receptor potential ankyrin 1 (TRPA1) activator, in uninjured female and male C57BL/6 mice. Priming (i.e. the first hit) was induced by three consecutive daily episodes of restraint stress; repeated umbellulone was also evaluated for potential priming effects. Sixteen days after the first restraint stress, mice received inhalational umbellulone (i.e. the second hit) to elicit migraine-like pain. Medications currently used for acute or preventive migraine therapy including propranolol (a beta blocker) and sumatriptan (5HT1_B/D agonist), as well as olcegepant, an experimental calcitonin gene related peptide (CGRP) receptor antagonist and nor-Binaltorphimine (nor-BNI), an experimental long-acting kappa opioid receptor (KOR) antagonist, were investigated for their efficacy to block priming and prevent or reverse umbellulone-induced allodynia in primed animals. To assess migraine-like pain, cutaneous allodynia was determined by responses to periorbital or hindpaw probing with von Frey filaments.

RESULTS

Repeated restraint stress, but not umbellulone exposure, produced transient cutaneous allodynia that resolved within 16 d. Restraint stress produced long-lasting priming that persisted beyond 16 d, as demonstrated by reinstatement of cutaneous allodynia following inhalational umbellulone challenge. Pretreatment with propranolol or nor-BNI prior to restraint stress prevented both transient cutaneous allodynia and priming, demonstrated by a lack of umbellulone-induced cutaneous allodynia. Following establishment of restraint stress priming, olcegepant, but not propranolol or nor-BNI, prevented umbellulone-induced cutaneous allodynia. When administered 1 h after umbellulone, sumatriptan, but not olcegepant, reversed umbellulone-induced cutaneous allodynia in restraint stress-primed rats.

CONCLUSION

We have developed a novel injury-free model with translational relevance that can be used to study mechanisms relevant to migraine-like pain and to evaluate novel acute or preventive treatments. Restraint stress priming induced a state of vulnerability to a subthreshold stimulus that has been referred to as "latent sensitization". The development of latent sensitization could be prevented by blockade of stress pathways with propranolol or with a kappa opioid receptor antagonist. Following establishment of latent sensitization, subthreshold stimulation with umbellulone reinstated cutaneous allodynia, likely from activation of meningeal TRPA1-expressing nociceptors. Accordingly, in restraint stress-primed animals, sumatriptan reversed umbellulone-induced cutaneous allodynia, supporting peripheral sites of action, while propranolol and nor-BNI were not effective. Surprisingly, olcegepant was effective in mice with latent sensitization when given prior to, but not after, umbellulone challenge, suggesting time-dependent contributions of calcitonin gene-related peptide receptor signaling in promoting migraine-like pain in this model. Activation of the calcitonin gene-related peptide receptor participates in initiating, but has a more limited role in maintaining, pain responses, supporting the efficacy of small molecule calcitonin gene-related peptide antagonists as preventive medications. Additionally, the effectiveness of sumatriptan in reversal of established pain thus suggests modulation of additional, non-calcitonin gene-related peptide receptor-mediated nociceptive mechanisms. Kappa opioid receptor antagonists may represent a novel preventive therapy for stress-related migraine.

Ocular Surface Pain: A Narrative Review

Ocular surface pain is a frequent cause of visits to an eye care provider and has a substantial impact on healthcare cost, yet a complete understanding of its causative factors and tools for diagnostic workup are notably missing in many eye clinics. The cornea has the densest sensory innervation in the human body and has the potential to be a powerful producer of pain. Pain can manifest as a result of a noxious stimulus or disruption in the ocular surface anatomy (nociceptive pain), or it can result from abnormalities in the ocular surface neurosensory apparatus itself (neuropathic pain). Novel advances in neurobiology have sought to differentiate the two entities, particularly to identify when chronic dry eye symptomatology is driven by neuropathic ocular pain. In this review, we seek to provide an overview of the prevalence, physiologic factors, and management of ocular surface pain complaints.