Ten open questions in migraine prophylaxis with monoclonal antibodies blocking the calcitonin-gene related peptide pathway: a narrative review

The monoclonal antibodies (mAbs) blocking the calcitonin-gene related peptide (CGRP) pathway, collectively called here "anti-CGRP/rec mAbs", have dramatically improved preventive migraine treatment. Although their efficacy and tolerability were proven in a number of randomized controlled trials (RCTs) and, maybe even more convincingly, in real world settings, a number of open questions remain. In this narrative review, we will analyze published data allowing insight in some of the uncertainties related to the use of anti-CGRP/rec mAbs in clinical practice: their differential efficacy in migraine subtypes, outcome predictors, switching between molecules, use in children and adolescents, long-term treatment adherence and persistence, effect persistence after discontinuation, combined treatment with botulinum toxin or gepants, added-value and cost effectiveness, effectiveness in other headache types, and potential contraindications based on known physiological effects of CGRP. While recent studies have already provided hints for some of these questions, many of them will not find reliable and definitive answers before larger studies, registries or dedicated RCTs are available.

A Scoping Review and Meta-Analysis of Anti-CGRP Monoclonal Antibodies: Predicting Response

Calcitonin gene-related peptide-targeted monoclonal antibodies (CGRP mAbs) are increasingly being used as preventive treatments for migraine. Their effectiveness and safety were established through numerous randomized placebo-controlled trials and real-world studies, yet a significant proportion of patients do not respond to this treatment, and currently, there is a lack of accepted predictors of response to guide expectations, as data from studies so far are lacking and inconsistent. We searched Embase and MEDLINE databases for studies reporting on predictors of response to CGRP and/or CGRP-receptor (CGRP-R) mAbs, defined as a 30% or 50% reduction in monthly headache or migraine days at varying durations of follow-up. Quantitative synthesis was performed where applicable. We found 38 real-world studies that investigated the association between various predictors and response rates. Based on these studies, good response to triptans and unilateral pain with or without unilateral autonomic symptoms are predictors of a good response to CGRP(-R) mAbs. Conversely, obesity, interictal allodynia, the presence of daily headaches, a higher number of non-successful previous prophylactic medications, and psychiatric comorbidities including depression are predictive of a poor response to CGRP(-R) mAbs. Future studies should confirm these results and help to generate more tailored treatment strategies in patients with migraine.

CGRP physiology, pharmacology, and therapeutic targets: migraine and beyond

Calcitonin gene-related peptide (CGRP) is a neuropeptide with diverse physiological functions. Its two isoforms (α and β) are widely expressed throughout the body in sensory neurons as well as in other cell types, such as motor neurons and neuroendocrine cells. CGRP acts via at least two G protein-coupled receptors that form unusual complexes with receptor activity-modifying proteins. These are the CGRP receptor and the AMY1 receptor; in rodents, additional receptors come into play. Although CGRP is known to produce many effects, the precise molecular identity of the receptor(s) that mediates CGRP effects is seldom clear. Despite the many enigmas still in CGRP biology, therapeutics that target the CGRP axis to treat or prevent migraine are a bench-to-bedside success story. This review provides a contextual background on the regulation and sites of CGRP expression and CGRP receptor pharmacology. The physiological actions of CGRP in the nervous system are discussed, along with updates on CGRP actions in the cardiovascular, pulmonary, gastrointestinal, immune, hematopoietic, and reproductive systems and metabolic effects of CGRP in muscle and adipose tissues. We cover how CGRP in these systems is associated with disease states, most notably migraine. In this context, we discuss how CGRP actions in both the peripheral and central nervous systems provide a basis for therapeutic targeting of CGRP in migraine. Finally, we highlight potentially fertile ground for the development of additional therapeutics and combinatorial strategies that could be designed to modulate CGRP signaling for migraine and other diseases.

An observational study on monoclonal antibodies against calcitonin-gene-related peptide and its receptor

BACKGROUND AND PURPOSE

Based on their pharmacological target, two classes of calcitonin-gene-related peptide (CGRP) monoclonal antibodies (mAbs) have been identified: antibodies against the CGRP ligand-galcanezumab, fremanezumab, eptinezumab-and antibodies against the CGRP receptor (CGRP-R), erenumab. The aim of the present study was to compare anti-CGRP versus anti-CGRP-R mAbs in patients with high frequency episodic and chronic migraine.

METHODS

All patients on monthly treatment with anti-CGRP mAbs with an available 6 months' follow-up at January 2022 were included. Data on efficacy outcome were collected following one (T1), three (T3) and six (T6) months of treatment, and included monthly headache/migraine days, the Migraine Disability Assessment Scale (MIDAS) and Headache Impact Test 6 (HIT-6) scores, pain intensity, analgesics consumption and response rates (>50% headache days reduction compared to baseline).

RESULTS

In all, 152 patients were enrolled, of whom 68 were in treatment with anti-CGRP mAbs (49 galcanezumab, 19 fremanezumab) and 84 with the anti-CGRP-R (erenumab). MIDAS scores were significantly lower in the anti-CGRP group at T1 and T3 (respectively p < 0.02 and p < 0.03) as well as the number of mean migraine days at T3 (p < 0.01). At T3 and T6 outcome measures were comparable, although a significantly higher percentage of super-responders was found in the anti-CGRP group (respectively p < 0.04 and p < 0.05), with a similar overall percentage of responders.

CONCLUSIONS

The present study on a real-world sample confirms the beneficial effect of both anti-CGRP and anti-CGRP-R mAbs, with a more favorable outcome for anti-CGRP antibodies.

Clinical evaluation of super-responders vs. non-responders to CGRP(-receptor) monoclonal antibodies: a real-world experience

BACKGROUND

Clinical trials and real-world studies revealed a spectrum of response to CGRP(-receptor) monoclonal antibodies (mAbs) in migraine prophylaxis, ranging from no effect at all to total migraine freedom. In this study, we aimed to compare clinical characteristics between super-responders (SR) and non-responders (NR) to CGRP(-receptor) mAbs.

METHODS

We performed a retrospective cohort study at the Headache Center, Charité - Universitätsmedizin Berlin. The definition of super-response was a ≥ 75% reduction in monthly headache days (MHD) in the third month after treatment initiation compared to the month prior to treatment begin (baseline). Non-response was defined as ≤ 25% reduction in MHD after three months of treatment with a CGRP-receptor mAb and subsequent three months of treatment with CGRP mAb, or vice versa. We collected demographic data, migraine disease characteristics, migraine symptoms during the attacks in both study groups (SR/NR) as well as the general medical history. SR and NR were compared using Chi-square test for categorical variables, and t-test for continuous variables.

RESULTS

Between November 2018 and June 2022, n = 260 patients with migraine received preventive treatment with CGRP(-receptor) mAbs and provided complete headache documentation for the baseline phase and the third treatment month. Among those, we identified n = 29 SR (11%) and n = 26 NR (10%). SR reported more often especially vomiting (SR n = 12/25, 48% vs. NR n = 4/22, 18%; p = 0.031) and typical migraine characteristics such as unilateral localization, pulsating character, photophobia and nausea. A subjective good response to triptans was significantly higher in SR (n = 26/29, 90%) than in NR (n = 15/25, 60%, p = 0.010). NR suffered more frequently from chronic migraine (NR n = 24/26, 92% vs. SR n = 15/29, 52%; p = 0.001), medication overuse headache (NR n = 14/24, 58% versus SR n = 8/29, 28%; p = 0.024), and concomitant depression (NR n = 17/26, 65% vs. SR n = 8/29, 28%; p = 0.005).

CONCLUSION

Several clinical parameters differ between SR and NR to prophylactic CGRP(-R) mAbs. A thorough clinical evaluation prior to treatment initiation might help to achieve a more personalized management in patients with migraine.

Predictors of response to galcanezumab in patients with chronic migraine: a real-world prospective observational study

BACKGROUND

Despite high efficacy and tolerability, not all patients with chronic migraine benefit from anti-CGRP monoclonal antibodies. We aimed to identify the clinical predictors of the response to galcanezumab treatment in patients with chronic migraine from real-world data.

METHODS

We prospectively recruited patients with CM who underwent galcanezumab injections between December 2019 and February 2022. Treatment response was determined after three months of follow-up and was defined as ≥ 50% reduction in monthly headache days. The migraine characteristics, comorbidities, and other treatment responses were compared between the responder and non-responder groups.

RESULTS

Of 238 patients with CM, 153 (64.3%) showed treatment response. The responder group was younger, had lower frequency of baseline headache days, and had more accompanying symptoms such as nausea, vomiting, and photophobia. Better triptan response and less depression were also observed in the responder group. Multivariable regression analysis revealed that the everyday headache (OR = 0.351, 95% CI = 0.133-0.874, p = 0.017), depression (OR = 0.439, 95% CI = 0.216-0.896, p = 0.024) and absence of accompanying symptoms (OR = 0.314, 95% CI = 0.118-0.834, p = 0.020) were significantly associated with response to galcanezumab treatment.

CONCLUSIONS

Our real-world data showed the efficacy of galcanezumab in patients with CM, regardless of medication overuse. Everyday headache, presence of depression, and absence of accompanying symptoms of migraine were significant predictors of a poor response.

Efficacy of erenumab and factors predicting response after 3 months in treatment resistant chronic migraine: a clinical service evaluation

Background

Calcitonin gene-related peptide (CGRP) inhibitors have been developed as options for treatment of chronic and episodic migraine. We present our experience of the use of erenumab in a tertiary headache centre.

Methods

This was a prospective clinical audit of all patients commenced on erenumab following a locally agreed pathway and criteria over a consecutive period. Patients received monthly erenumab 140 mg for 3 months. Data were collected prospectively at baseline and 3 months follow up.

Results

One hundred three patients were commenced on erenumab during the study period. Patients had tried a median of 7 previous prophylactics, including onabotulinum toxin A in 94%. At 3 months there was a reduction in median total (28 to 20, 29% reduction, p < 0.0001) and severe (15 to 5, 67% reduction, p < 0.0001) headache days. 39.8% of patients achieved at least a 30% reduction in total headache days; 61.8% of patients achieved at least a 50% reduction in severe headache days. Meeting either of these thresholds was considered a positive response, 68% of patients achieved this. Presence of daily headache pattern was negatively associated with response, (56% response vs. 90% without daily headache, p = 0.0003). There was no association between age, gender, presence of medication overuse or number of previously tried prophylactic treatments and response to erenumab. 43% of patients reported at least one adverse effect, most commonly constipation (26%); treatment was discontinued in 3 patients due to adverse effects.

Conclusions

Erenumab was an effective treatment for chronic migraine in this treatment resistant population over 3 months of follow up. Presence of daily headache predicted poorer response but there was still a significant positive response rate in this group.

Cerebral Blood Flow and Other Predictors of Responsiveness to Erenumab and Fremanezumab in Migraine-A Real-Life Study

Introduction

Monoclonal antibodies (mAbs) showed efficacy in migraine prevention. The aim of this study was to check if baseline clinical parameters and cerebral blood flow (CBF) measured by transcranial Doppler (TCD) may help predict mAbs efficacy.

Methods

Electronic charts of migraineurs treated with erenumab or fremanezumab, with baseline TCD evaluations were collected, including data on migraine type, pain localization, monthly migraine days (MMD), medication overuse headache (MOH), mean blood flow velocity (Vm), and pulsatility index (PI) in cerebral arteries.

Results

A total of 123 patients were enrolled, mean age 38, 75 years, 87 with chronic migraine, 61 with MOH, 72 were good responders (GR), and reported ≥50% reduction in MMD, 43 ≥75% reduction in MMD. Baseline Vm values in MCAs were significantly lower in GR as compared with non-responders. MAbs responsiveness ≥50% was positively associated with unilateral pain localization (OR: 6.53, 95% CI: 2.01–23.93; p = 0.003) and HIT-6 score (OR: 1.14, 95% CI: 1.01–1.30; p = 0.036) whereas negatively associated with Vm in right MCA (OR: 0.96, 95% CI: 0.92–0.99; p = 0.012), and having no relatives with migraine (OR: 0.40, 95% CI: 0.16–0.95; p = 0.040).

Conclusions

Baseline Vm in MCA is lower in mAbs GR as compared with non-responders which may reflect increased secretion of CGRP with further vasodilation in GR. Simple clinical features and baseline CBF in anterior circulation might help to predict the patient's responsiveness.

Erenumab for Migraine Prevention in a 1-Year Compassionate Use Program: Efficacy, Tolerability, and Differences Between Clinical Phenotypes

During a 1-year compassionate use program, 156 patients with migraine self-administered a monthly dose of erenumab 140 mg with a subcutaneous autoinjector. Main inclusion criteria were: ≥ 4 migraine days/month and ≥two prior prophylactic treatment failures. The patients covered the migraine severity spectrum from episodic migraine (EM) (n = 80) to chronic migraine (CM) (n = 76). During the 3rd month of treatment, monthly headache days decreased by 45.7% in EM and 35.5% in CM. The 50% responder rate for reduction in monthly headache days was significantly higher in EM (55%) than in CM (43%) (p = 0.05). In both the migraine subgroups, the clinical improvement vs. baseline was already significant during the 1st month of treatment (p < 0.001). There were also significant reductions in mean headache severity, duration, and monthly days with acute drug intake. The 30% responder rate at 3 months was 60% in CM and 54.1% of patients reversed from CM to EM. The therapeutic effect was maintained at 12 months when 50% responder rates, considering discontinuation for lack of efficacy or adverse effects as 0% response, still were 51% in EM and 41% in CM. A total of 10 patients with EM (12.5%) and 23 patients with CM (30.3%) had discontinued treatment, considering the treatment as ineffective. At 3 months, 48% of patients reported non-serious adverse events among which the most frequent was constipation (20.5%); corresponding figures at 12 months were 30 and 15%. Discontinuation due to an adverse effect for the entire 12 month period was rare (3.8%). The lower efficacy in CM than in EM was mainly due to a very low 50% responder rate in patients with CM with continuous pain (13%) as compared to CM with pain-free periods (58%) (p < 0.001). Similarly, the 50% responder rate was lower in patients with ≥two prior prophylactic treatment failures (40.5%) compared to those with two failures (70%) (p < 0.05). There was no significant efficacy difference between low (4-7 migraine days/month, n = 22) and high frequency (8-14 days, n = 59) EM nor between patients with CM with (n = 50) or without (n = 26) acute medication overuse. Erenumab had no effect on the frequency of auras. Taken together, erenumab 140 mg monthly was highly effective for migraine prophylaxis over the whole severity spectrum of the disease, except in patients with continuous headaches. Its effect is significant after the first injection, quasi-maximal after the second injection, and does not wear off after 12 months. The most frequent adverse effect was constipation. These results are compared to those published for erenumab in the pivotal randomized placebo-controlled trials and to those reported in several recent real-world studies.