Anti-CGRP Ligand mAbs (Galcanezumab, Fremanezumab) Show Distinct Plasma CGRP Dynamics from Erenumab in Migraine
Background
Migraine is a debilitating neurological disorder characterized by severe headaches, often accompanied by other symptoms. Neuropeptides like Calcitonin gene-related peptide (CGRP), Vasoactive Intestinal Peptide (VIP), and Pituitary Adenylate Cyclase-Activating Peptide (PACAP) are crucial in its pathophysiology, particularly CGRP, which is elevated during attacks. Traditional prophylactic treatments often have limited efficacy and side effects. Anti-CGRP(R) monoclonal antibodies (mAbs) represent a targeted breakthrough, but understanding how they impact plasma biomarker levels, especially differentiating between anti-ligand (targeting CGRP itself) and anti-receptor (targeting the CGRP-receptor) mechanisms, is vital for optimizing treatment strategies and identifying potential predictive biomarkers.
Study Design
This observational cohort study enrolled 56 migraine patients initiating prophylactic anti-CGRP(R) mAbs between February 2022 and February 2023. Patients received either erenumab (anti-receptor, n=26), galcanezumab (anti-ligand, n=16), or fremanezumab (anti-ligand, n=14). Blood samples were collected at baseline (T0), three months (T1), six months (T2), and twelve months (T3). Plasma levels of CGRP, VIP, and PACAP were quantified using a validated radioimmunoassay and commercially available ELISA kits. Clinical response was defined as a ≥50% reduction in monthly migraine days after six months of treatment.
Results
Overall, a significant 80.3% (45 out of 56) of patients achieved a clinical response to anti-CGRP(R) mAbs. The study found no correlation between baseline plasma levels of CGRP, VIP, or PACAP and the subsequent clinical response to therapy. Regarding CGRP dynamics, significant differences emerged between the anti-receptor and anti-ligand therapies. In patients treated with erenumab, plasma CGRP levels did not show a significant change over the entire treatment period (T1-T3).
Key Findings
- 80.3% of migraine patients responded to anti-CGRP(R) monoclonal antibody therapy.
- No correlation was found between baseline CGRP, VIP, or PACAP plasma levels and clinical response.
- Plasma CGRP levels did not significantly change in patients treated with erenumab (anti-receptor mAb).
- Significant differences in CGRP dynamics were observed between anti-receptor (erenumab) and anti-ligand (galcanezumab, fremanezumab) therapies.
Why It Matters
This study highlights a critical distinction in how different anti-CGRP therapies affect circulating CGRP levels, which has implications for biomarker monitoring. Clinicians and patients should understand that plasma CGRP levels may not decrease with anti-receptor mAbs like erenumab, even if the treatment is effective, because the ligand is still present but blocked from binding. This means CGRP plasma levels cannot be used as a universal biomarker for treatment efficacy across all anti-CGRP(R) mAb types. The lack of correlation between baseline neuropeptide levels and clinical response suggests that these specific plasma biomarkers may not predict who will respond to anti-CGRP(R) mAb therapy, necessitating further research into other predictive markers.
migraine
cgrp
erenumab
galcanezumab
fremanezumab
monoclonal-antibody