Switching between anti-CGRP antibodies shows modest benefit, mainly for patients who switched due to ineffectiveness | Research

The takeaway

Among 66 switch instances in 54 chronic migraine patients, switching anti-CGRP mAbs showed non-significant overall improvement (15% achieved ≥50% reduction), but significant benefits when switching for ineffectiveness specifically, with some side effect improvement.

Switch for ineffectiveness, not side effects
Significant headache improvement was only seen when patients switched anti-CGRP drugs due to ineffectiveness (p=0.044)—switching for side effects showed no significant benefit

What the researchers found

Overall: -1.2 red days (NS), 15% ≥50% responders, 33% ≥30% responders. Switched for ineffectiveness only: significant ↓headache days (p=0.044). Side effects: improved/resolved in 12/20, new symptoms in 8/20. 66 switches in 54 patients.

Why it matters

When patients fail one anti-CGRP drug, clinicians need to know whether trying another is worthwhile. This study suggests switching for ineffectiveness (not side effects) has the best chance of success.

How the study worked

Retrospective analysis. 54 chronic migraine patients, 66 switch instances. Headache diary data. 6-month post-switch follow-up. Primary outcome: red days at 3 months.

What this study cannot tell us

Retrospective. Small sample (54 patients). No control group. Multiple switch directions. Modest overall effects.

How to read the evidence

Small retrospective real-world study. Provides practical guidance but limited by sample size.

When this study was published

Published in 2025.

The bigger picture

Despite targeting the same pathway, anti-CGRP mAbs have different pharmacological properties (receptor vs ligand binding, half-life, dosing). These differences may explain why some patients respond to a switch.

Questions still open

Which specific switch direction (e.g., erenumab→fremanezumab) works best?
Does switching mechanism (receptor vs ligand binding) predict success?
Should patients failing CGRP mAbs try gepants instead of switching mAbs?

Common questions

Should I try a different CGRP drug if the first one does not work?

This study suggests yes—if the first anti-CGRP drug was not effective enough, switching to a different one can help some patients. About 33% showed at least 30% improvement. However, if you are switching because of side effects, the benefit is less clear—about 60% saw side effect improvement but 40% developed new symptoms.

Are all anti-CGRP migraine drugs the same?

No. While they all target the CGRP pathway, they work differently: some block the CGRP molecule itself (fremanezumab, galcanezumab) while one blocks the receptor (erenumab). They also differ in half-life and dosing frequency. These differences may explain why patients respond differently to each drug.

Read the original research

Switching anti-CGRP monoclonal antibodies in chronic migraine: real-world observations of erenumab, fremanezumab and galcanezumab.

European journal of hospital pharmacy : science and practice, 32(2), 178-185

View on PubMed ↗Publisher’s paper ↗

Citation

Talbot, Jamie; Stuckey, Rebecca; Wood, Natasha; Gordon, Alexander; Crossingham, Ginette; Weatherby, Stuart. (2025). Switching anti-CGRP monoclonal antibodies in chronic migraine: real-world observations of erenumab, fremanezumab and galcanezumab.. European journal of hospital pharmacy : science and practice, 32(2), 178-185. https://doi.org/10.1136/ejhpharm-2023-003779