Question explored with the scientific record
Conversation so far
- 1 Why is Ajovy available only in 225mg syringes? Why is there no 175mg, for example? How did the drug manufacturer arrive at that dose and can I see that data? What dose ranges did they test?
- 2 What does it imply if an adult can take Ajovy 225mg every two months instead of monthly? does it imply the 225mg dose is an overshoot for this particular person? if the half-life is 30 days and the drug works great for 60 days, what do we learn from that?
- 3 Do any guidelines address stretching Ajovy dosing beyond 30 days?
- 4 Are there any studies on dosing at 45 or 60 days for Ajovy?
- 5 what are the long-term impacts of mAbs?
- 6 what about mAbs in general, not these ones specifically. what do we know about their long-term safety profile?
- 7 explain to me in layman's terms what CGRP mAbs are doing mechanistically.
Answered on this page ↓
explain to me in layman's terms what CGRP mAbs are doing mechanistically.
The short version: CGRP mAbs work by grabbing and neutralizing the CGRP molecule itself, or by blocking its receptor, which interrupts the chain of events that drives migraine pain.
CGRP is a small protein released by nerve endings around blood vessels in the head. When it binds to its receptor on those vessels, it makes them widen and triggers inflammation, which is part of the migraine attack [1]. The antibodies are engineered to act like a sponge. Some, like fremanezumab and eptinezumab, bind directly to CGRP and stop it from reaching the receptor [4, 6]. Others, like erenumab, block the receptor itself so CGRP cannot dock [7]. Either way, the signal is cut off before the pain cascade starts.
The evidence for benefit is real but modest. In chronic migraine, fremanezumab cut migraine days by about 38 to 41 percent versus 18 percent for placebo [4]. Eptinezumab in chronic migraine reduced days by about 7.7 to 8.2 per month versus 5.6 for placebo [6]. About half of patients got a 50 percent or better reduction [4, 5]. These are meaningful numbers, but they mean roughly half of patients did not get that response.
The evidence base has real limits. The trials run 12 weeks to two years, not decades [4, 6]. Long-term safety data beyond that is thin. The main reported harms are injection-site reactions, with no cardiovascular or cerebrovascular problems found in the fremanezumab trials [4]. But CGRP also does other jobs in the body, like regulating stomach acid and immune cell activity [2, 3]. What blocking it for years does to those systems is not answered by these records.
| Drug | Population | Migraine day reduction vs placebo | 50% responder rate |
|---|---|---|---|
| Fremanezumab (chronic) | 1,130 patients | 38–41% vs 18% | ~41% monthly |
| Eptinezumab (chronic) | 1,121 patients | −7.7 to −8.2 vs −5.6 days | 57–61% vs 39% |
My call: CGRP mAbs work by neutralizing CGRP or its receptor, with real but partial benefit and no long-term safety data beyond two years. Confidence: moderate for mechanism and short-term benefit, low for long-term safety.
Sources used 7
-
CGRP Receptor Antagonists and 5-HT1F Receptor Agonist in the Treatment of Migraine
This review discusses the role of calcitonin gene-related peptide (CGRP) in migraine pathophysiology and evaluates the efficacy, safety, and tolerability of new CGRP receptor antagonists (gepants) and 5-HT1F receptor agonists (ditans) in migraine treatment.
DOI: 10.3390/jcm10071429 -
Calcitonin gene related peptide inhibits basal, pentagastrin, histamine, and bethanecol stimulated gastric acid secretion.
Intravenous calcitonin gene-related peptide dose-dependently inhibited basal and pentagastrin-, histamine-, and bethanechol-stimulated gastric acid secretion in rats; full peptide and intact vagal cholinergic pathway were required.
DOI: 10.1136/gut.26.6.550 -
Calcitonin Gene-Related Peptide Decreases Expression of HLA-DR and CD86 by Human Dendritic Cells and Dampens Dendritic Cell-Driven T Cell-Proliferative Responses Via the Type I Calcitonin Gene-Related Peptide Receptor
Calcitonin gene-related peptide decreases expression of HLA-DR and CD86 by human dendritic cells and dampens dendritic cell-driven T cell-proliferative responses via the type I calcitonin gene-related peptide receptor.
DOI: 10.4049/jimmunol.164.7.3494 -
FREMANEZUMAG (FREMANEZUMAB DAN MAGNESIUM) SEBAGAI INOVASI DALAM PENCEGAHAN SERANGAN MIGRAIN
A literature review argues that combining fremanezumab (anti-CGRP antibody) with magnesium offers an innovative, effective and safe prophylaxis for migraine attacks.
DOI: 10.26618/aimj.v3i1.4154 -
Fremanezumab: a disease-specific option for the preventive treatment of migraine, including difficult-to-treat migraine
Fremanezumab, a CGRP-targeting monoclonal antibody, reduces monthly migraine days and related disability across chronic and episodic migraine, including difficult-to-treat cases, with durable benefits seen in long-term use and in patients who previously failed multiple preventiv…
DOI: 10.1042/etls20200018 -
Eptinezumab for the treatment of migraine
An expert opinion/review evaluating eptinezumab (ALD403) as a quarterly IV preventive treatment for episodic and chronic migraine, detailing its pharmacology, phase 2/3 efficacy/safety data, rapid onset, PK characteristics, and positioning within migraine therapy.
DOI: 10.1080/14712598.2021.1931678 -
EHMTI-0315. AMG 334, the first potent and selective human monoclonal antibody antagonist against the CGRP receptor
This study characterizes AMG 334, a potent and selective human monoclonal antibody antagonist against the CGRP receptor, demonstrating its efficacy in inhibiting CGRP binding and its pharmacodynamic effects in a cynomolgus macaque model.
DOI: 10.1186/1129-2377-15-s1-g43