Reviews/Anti CGRP Antibodies/Responder rates in episodic migraine
Episodic Migraine · CGRP-EMR-02 · v2
Across this corpus, antibodies that block CGRP clearly reduce migraine days and produce a meaningful share of patients who improve by at least half, so efficacy in episodic migraine is not in doubt. What the episodic-specific evidence does not show is that the share of such responders is high. The cleanest episodic figures are moderate: about 30% at three months rising to roughly 52% after three years in people who had already failed two to four other treatments [9][41], and 48% among episodic patients switched from another antibody [15]. The largest first-line episodic trials measured how many fewer migraine days patients had rather than reporting a responder percentage, and much of the rest of the corpus studied chronic or mixed populations [2][3]. The panel accepted the efficacy but not the word 'high', because the episodic numbers that exist are moderate and come from harder-to-treat groups.
The corpus consistently shows anti-CGRP antibodies reduce monthly migraine days in episodic migraine and generate ≥50% responders. The first-line episodic RCTs report day reductions and significant responder endpoints without a responder percentage: fremanezumab cut migraine days from 8.9 to 4.9 [2], and EVOLVE-1 met its ≥50% secondary endpoints after multiplicity adjustment [3]. Where episodic responder percentages are reported, they are moderate: LIBERTY gives 29.9% at weeks 9-12 rising to 52.3% at three years [9][41], and the FINESSE switch subgroup gives 48.0% in episodic patients [15]. These episodic figures all derive from difficult-to-treat populations (two to four prior failures [9][41]; prior-antibody switch [15]). The contested point: The division is over the qualifier 'high': the direction and fact of efficacy are agreed, but every episodic-specific responder number in the corpus is moderate and drawn from refractory or switch populations [9][41][15], while the first-line episodic trials that would best test a general rate do not quote a responder percentage [2][3]. Whether moderate rates in difficult-to-treat cohorts can stand in for a general episodic-migraine responder rate is the unresolved point.
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One reviewer's only job is to attack the finding. The challenges below were weighed before the grade was set.
'High' responder rates is unsupported: the single cleanest EM responder figure at the primary 12-week timepoint (LIBERTY [9]) is 29.9%, and other EM figures sit at 48% [15] or reach 52.3% only at 3 years [41] — these are moderate, not high.
Population drift: a large share of included cohorts are chronic migraine or mixed HFEM+CM ([10][12][17][19][20][23][31][32][33][34][35][36]), whose responder rates cannot be read as episodic-migraine responder rates.
Where it remains uncertain. The strongest first-line episodic RCTs report only mean migraine-day reductions [2] or that responder endpoints were significant [3], leaving the claim's headline metric unquantified in the cleanest episodic trials.
Aleatory
Responder rates vary widely across individuals and timepoints even within one trial, from 29.9% early to 52.3% late in the same episodic cohort [9][41].
Epistemic
The pivotal first-line episodic RCTs report day reductions or significance only, so the claim's headline metric is unmeasured in the corpus's strongest episodic trials [2][3].
Inferential
The corpus supplies responder percentages but no benchmark defining which rates count as high, so the qualifier cannot be adjudicated from the numbers alone.
The load-bearing papers from a corpus of 42, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Pivotal EM RCT with responder endpoints met but no responder percentage reported in abstract
“Secondary measures included at least 50%, at least 75%, and 100% reduction in monthly migraine headache days”
Panel auditInternal validity: high · scope of inference: Galcanezumab efficacy in episodic migraine with or without aura, no concomitant preventives allowed.Key limitations: responder percentages not given in abstract · only MMD-day magnitudes reported
Direct EM responder data: 12-week ≥50% rate of 29.9% is moderate, not high, in difficult-to-treat EM
“Among patients continuing erenumab, the 50% responder rate increased from 29.9% at weeks 9 to 12 to 44.3% at weeks 61 to 64.”
Panel auditInternal validity: low · scope of inference: Long-term erenumab responder rate in episodic migraine with 2-4 prior preventive failures.Key limitations: treatment-resistant selected EM subgroup · open-label, Class IV
EM subgroup ≥50% responder rate of 48.0% in switch patients
“Switch to fremanezumab led to ≥ 50% MMD reduction in 42.8% of migraine patients, with higher response rate in EM (48.0%) than in CM patients (36.5%).”
Panel auditInternal validity: medium · scope of inference: Fremanezumab responder rate in episodic migraine patients switching from a prior anti-CGRP mAb.Key limitations: switch (prior-mAb-failure) population · no p-value for responder rate · interim data
EM RCT demonstrates efficacy via mean day reduction but provides no responder rate
“mean migraine days per month decreased from 8.9 days to 4.9 days in the fremanezumab monthly dosing group”
Panel auditInternal validity: high · scope of inference: Mean migraine-day reduction with fremanezumab in episodic migraine without multiple prior preventive failures.Key limitations: responder rate not reported, only mean days · patients with ≥2 prior class failures excluded
4 of 42 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
Efficacy in episodic migraine is supported, but the specific assertion of 'high' responder rates is an overreach given moderate EM-specific figures drawn largely from difficult-to-treat populations.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
First-line EM responder percentage. The claim's headline metric is unquantified in the corpus's strongest first-line episodic RCTs, which report day reductions [2] or only that responder endpoints were significant [3]. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: Extract or report the ≥50%, ≥75% and 100% responder percentages from a first-line, prevention-naïve episodic-migraine RCT population.
Open question: What is the ≥50% responder rate in first-line, prevention-naïve episodic migraine? Why it is still open: The pivotal episodic RCTs in the corpus report day reductions or significance rather than a responder percentage [2][3], and PROMISE-1 is a results-free abstract [27].
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 21 Oct 2026 · protocol v0.19