Cluster Headache Genomewide Association Study and Meta-Analysis Identifies Eight Loci and Implicates Smoking as Causal Risk Factor.

OBJECTIVE: The objective of this study was to aggregate data for the first genomewide association study meta-analysis of cluster headache, to identify genetic risk variants, and gain biological insights. METHODS: A total of 4,777 cases (3,348 men and 1,429 women) with clinically diagnosed cluster headache were recruited from 10 European and 1 East Asian cohorts. We first performed an inverse-variance genomewide association meta-analysis of 4,043 cases and 21,729 controls of European ancestry. In a secondary trans-ancestry meta-analysis, we included 734 cases and 9,846 controls of East Asian ancestry. Candidate causal genes were prioritized by 5 complementary methods: expression quantitative trait loci, transcriptome-wide association, fine-mapping of causal gene sets, genetically driven DNA methylation, and effects on protein structure. Gene set and tissue enrichment analyses, genetic correlation, genetic risk score analysis, and Mendelian randomization were part of the downstream analyses. RESULTS: The estimated single nucleotide polymorphism (SNP)-based heritability of cluster headache was 14.5%. We identified 9 independent signals in 7 genomewide significant loci in the primary meta-analysis, and one additional locus in the trans-ethnic meta-analysis. Five of the loci were previously known. The 20 genes prioritized as potentially causal for cluster headache showed enrichment to artery and brain tissue. Cluster headache was genetically correlated with cigarette smoking, risk-taking behavior, attention deficit hyperactivity disorder (ADHD), depression, and musculoskeletal pain. Mendelian randomization analysis indicated a causal effect of cigarette smoking intensity on cluster headache. Three of the identified loci were shared with migraine. INTERPRETATION: This first genomewide association study meta-analysis gives clues to the biological basis of cluster headache and indicates that smoking is a causal risk factor. ANN NEUROL 2023;94:713-726.

Genome-Wide Association Study Identifies Risk Loci for Cluster Headache.

OBJECTIVE: This study was undertaken to identify susceptibility loci for cluster headache and obtain insights into relevant disease pathways. METHODS: We carried out a genome-wide association study, where 852 UK and 591 Swedish cluster headache cases were compared with 5,614 and 1,134 controls, respectively. Following quality control and imputation, single variant association testing was conducted using a logistic mixed model for each cohort. The 2 cohorts were subsequently combined in a merged analysis. Downstream analyses, such as gene-set enrichment, functional variant annotation, prediction and pathway analyses, were performed. RESULTS: Initial independent analysis identified 2 replicable cluster headache susceptibility loci on chromosome 2. A merged analysis identified an additional locus on chromosome 1 and confirmed a locus significant in the UK analysis on chromosome 6, which overlaps with a previously known migraine locus. The lead single nucleotide polymorphisms were rs113658130 (p = 1.92 × 10-17 , odds ratio [OR] = 1.51, 95% confidence interval [CI] = 1.37-1.66) and rs4519530 (p = 6.98 × 10-17 , OR = 1.47, 95% CI = 1.34-1.61) on chromosome 2, rs12121134 on chromosome 1 (p = 1.66 × 10-8 , OR = 1.36, 95% CI = 1.22-1.52), and rs11153082 (p = 1.85 × 10-8 , OR = 1.30, 95% CI = 1.19-1.42) on chromosome 6. Downstream analyses implicated immunological processes in the pathogenesis of cluster headache. INTERPRETATION: We identified and replicated several genome-wide significant associations supporting a genetic predisposition in cluster headache in a genome-wide association study involving 1,443 cases. Replication in larger independent cohorts combined with comprehensive phenotyping, in relation to, for example, treatment response and cluster headache subtypes, could provide unprecedented insights into genotype-phenotype correlations and the pathophysiological pathways underlying cluster headache. ANN NEUROL 2021;90:193-202.

Alemtuzumab in multiple sclerosis: A retrospective analysis of occult hemorrhagic magnetic resonance imaging lesions and risk factors.

BACKGROUND AND PURPOSE: Alemtuzumab, a monoclonal CD52 antibody, is a high-efficacy disease-modifying-therapy in relapsing-remitting multiple sclerosis (RRMS). Recently, intracerebral hemorrhage (ICH) was reported as a possible treatment-related adverse event. Arterial hypertension during infusion was suggested as a potential cause, although platelet or endothelial dysfunction may also contribute. This study aimed to screen for occult hemorrhagic cerebral lesions after alemtuzumab treatment and to further elucidate risk factors. METHODS: We included 30 RRMS patients who received alemtuzumab treatment at Ghent University Hospital or Sint-Jan Bruges Hospital. Retrospective data concerning vital signs, adverse effects and thrombocyte levels during treatment were collected. The occurrence of occult intracranial hemorrhagic lesions was assessed by magnetic resonance imaging with susceptibility-weighted imaging (SWI). RESULTS: The mean (standard deviation [SD]) systolic blood pressure (SBP) during the morning, afternoon and evening was 120 (3.38) mmHg during first administration and 114 (4.40) mmHg during second administration (N = 13). There was no significant increase in SBP when comparing morning, afternoon and evening per day, nor was there a significant difference in daily mean SBP between consecutive administration days. Thrombocyte count during treatment cycles ranged between 107 × 109 /L and 398 × 109 /L, with a mean (SD) absolute reduction of 59.3 × 109 /L (50.65) or a mean (SD) relative reduction of 25.0 (12.84)% (N = 20). No patient had ICH, nor did SWI show any cerebral microbleeds or other hemorrhagic lesions post-treatment (N = 23). CONCLUSIONS: In our patient population, alemtuzumab treatment was not associated with arterial hypertension, ICH or occult microbleeds. Possible differences in administration regimen (ambulatory vs. in-hospital setting) and patient population (cardiovascular risk) might explain an increased risk in different populations.

PACAP38 and PAC1 receptor blockade: a new target for headache?

Pituitary adenylate cyclase activating polypeptide-38 (PACAP38) is a widely distributed neuropeptide involved in neuroprotection, neurodevelopment, nociception and inflammation. Moreover, PACAP38 is a potent inducer of migraine-like attacks, but the mechanism behind this has not been fully elucidated.Migraine is a neurovascular disorder, recognized as the second most disabling disease. Nevertheless, the antibodies targeting calcitonin gene-related peptide (CGRP) or its receptor are the only prophylactic treatment developed specifically for migraine. These antibodies have displayed positive results in clinical trials, but are not effective for all patients; therefore, new pharmacological targets need to be identified.Due to the ability of PACAP38 to induce migraine-like attacks, its location in structures previously associated with migraine pathophysiology and the 100-fold selectivity for the PAC1 receptor when compared to VIP, new attention has been drawn to this pathway and its potential role as a novel target for migraine treatment. In accordance with this, antibodies against PACAP38 (ALD 1910) and PAC1 receptor (AMG 301) are being developed, with AMG 301 already in Phase II clinical trials. No results have been published so far, but in preclinical studies, AMG 301 has shown responses comparable to those observed with triptans. If these antibodies prove to be effective for the treatment of migraine, several considerations should be addressed, for instance, the potential side effects of long-term blockade of the PACAP (receptor) pathway. Moreover, it is important to investigate whether these antibodies will indeed represent a therapeutic advantage for the patients that do not respond the CGRP (receptor)-antibodies.In conclusion, the data presented in this review indicate that PACAP38 and PAC1 receptor blockade are promising antimigraine therapies, but results from clinical trials are needed in order to confirm their efficacy and side effect profile.

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

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

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.

Safety and efficacy of percutaneous pulsed radiofrequency treatment at the C1-C2 level in chronic cluster headache: a retrospective analysis of 21 cases.

We performed a study of the safety and efficacy of percutaneous pulsed radiofrequency (PRF) treatment directed at C1 and C2 levels as performed at our local pain clinic in refractory chronic cluster headache (CCH) patients. We identified 21 CCH patients treated with PRF (240 s, max. 45 V, max. 42 °C) directed at the ganglion and/or nerve root of C1 and C2. Data were collected through retrospective analysis of patients' files and include demographic variables, onset and duration of the headache, mean attack frequency, and prior pharmacological treatment. Safety and reduction of attack frequency in the first 3 months after a first PRF treatment was the primary outcome parameter of this study. All patients had been treated with at least two prophylactic drugs and 19 (90%) had previously been treated with verapamil, lithium, and topiramate. Ten patients (47.6%) reported no meaningful effect, four patients (19%) reported a meaningful reduction of < 50%, and seven patients (33.3%) reported a reduction in headache burden of at least 50% in the 3 months following treatment. Two patients reported occurrence or increase in frequency of contralateral cluster attacks. No other adverse events were reported or detected at follow-up. Upper cervical PRF treatment appears to be a safe procedure that could prove effective in the treatment of patients with refractory CCH and warrants a prospective study.