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.

Salivary CGRP and Erenumab Treatment Response: Towards Precision Medicine in Migraine.

OBJECTIVE: We aimed (1) to analyze salivary calcitonin gene-related peptide (CGRP) levels in patients with migraine, (2) to predict erenumab response from baseline CGRP levels, and (3) to evaluate CGRP change post-treatment. METHODS: This is a prospective observational study that measured salivary CGRP levels in healthy controls (HCs), patients with episodic migraine (EM) and patients with chronic migraine (CM). Participants collected saliva samples at baseline and, the patients who were candidates to receive erenumab, also collected saliva after 3 doses of treatment. We quantified CGRP-like immunoreactivity (CGRP-LI) by enzyme-linked immunosorbent assay (ELISA) and we performed an analysis at baseline and post-treatment through generalized linear mixed models. RESULTS: At baseline, a higher headache frequency was associated with higher CGRP levels, those being even higher in the presence of depressive symptoms. A cutoff point (mean, 95% confidence interval [CI]) of 103.93 (95% CI = 103.35-104.51) pg/ml was estimated to differentiate migraine from controls with an area under the receiver operating characteristic (ROC) curve (AUC, 95% CI) of 0.801 (95% CI = 0.798-0.804). We also found that higher pretreatment salivary CGRP levels were statistically significantly associated to a higher probability of having 50% or greater reduction in headache frequency in patients with EM, but not in patients with CM. After 12 weeks of treatment with erenumab, salivary CGRP levels from patients within all spectrum of migraine frequency converged to similar CGRP values. In contrast, in patients with concomitant depressive symptoms, this convergence did not happen. INTERPRETATION: Patients with migraine not only have higher CGRP levels compared with HCs, but also the presence of depressive symptoms seems to increase salivary CGRP levels and we have evidence, for the first time, that baseline salivary CGRP concentration is associated with treatment response to erenumab. ANN NEUROL 2022;92:846-859.

Salivary CGRP can monitor the different migraine phases: CGRP (in)dependent attacks.

BACKGROUND: CGRP plays a key role in the transmission and modulation of nociceptive signals and is a critical component in the pathogenesis of migraine. OBJECTIVE: To assess saliva as a substrate to measure CGRP by comparing interictal levels in patients with episodic migraine and controls; and to evaluate CGRP's temporal profile during migraine attacks. METHODS: This prospective observational pilot study included young women with episodic migraine and healthy controls. We monitored salivary CGRP-like immunoreactivity (CGRP-LI) during 30 consecutive days and during migraine attacks. We considered six timepoints for the analysis: interictal (72h headache free), preictal (PRE-24h before the attack), ictal (headache onset, after 2h, after 8h), postictal (POST-24h after the attack). CGRP levels were quantified by ELISA. RESULTS: 44 women (22 with episodic migraine, 22 healthy controls) were recruited. Differences in interictal salivary levels of CGRP between patients and controls (Me [IQR]: 98.0 [80.3] (95% CI 56.6, 124.0) vs. 54.3 [44.0] (95% CI 42.2, 70.1) pg/mL, p = 0.034) were found. An increase in CGRP levels during migraine attacks was detected (pre:169.0 [95% CI 104.2-234.0]; headache onset: 247.0 [181.9-312.0]; after 2h: 143.0 [77.6-208.0]; after 8h: 169.0 [103.5-234.0], post: 173.0 [107.8-238.0]). Patients were classified as having CGRP-dependent (79.6%) and non-CGRP dependent migraine attacks (20.4%) according to the magnitude of change between preictal and ictal phase. Accompanying symptoms such as photophobia and phonophobia were significantly associated to the first group. CONCLUSIONS: Salivary CGRP-LI levels, which interictally are elevated in episodic migraine patients, usually increase during a migraine attack in the majority of patients. However, not every attack is CGRP-dependent, which in turn, might explain different underlying pathophysiology and response to treatment.