CGRP and Migraines: The Peptide Breakthrough

Pain Peptides

60.4% responders

In the EUREkA cohort of 1,340 migraine patients treated for two years, 60.4% achieved at least 50% reduction in monthly headache days with anti-CGRP monoclonal antibodies.

Caronna et al., Neurology, 2026

Caronna et al., Neurology, 2026

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Calcitonin gene-related peptide (CGRP) is a 37-amino-acid neuropeptide and the most potent vasodilator in the human body. Its role in migraine was suspected for decades before drugs targeting it reached the market. Today, eight CGRP-targeting medications are approved for migraine prevention or treatment, making CGRP the single most successful peptide drug target in neurology. The CGRP migraine story is also one of the clearest examples of how basic peptide science translates into transformative medicine. For a broader view of pain neuropeptides including substance P, see our pillar article.

How CGRP Triggers Migraines

CGRP is released from trigeminal sensory nerve fibers that innervate the meninges and cerebral blood vessels. During a migraine attack, trigeminal activation floods the trigeminovascular system with CGRP, producing three effects that generate migraine symptoms.

Vasodilation. CGRP dilates meningeal and cerebral arteries, increasing blood flow and contributing to the pulsating headache characteristic of migraine. It acts on CGRP receptors on vascular smooth muscle cells, triggering cyclic AMP-mediated relaxation.

Neurogenic inflammation. CGRP promotes mast cell degranulation and plasma protein extravasation in the meninges, creating a sterile inflammatory response around the trigeminal nerve terminals. This inflammation sensitizes pain receptors, lowering the threshold for pain signaling.

Central sensitization. CGRP released in the trigeminal nucleus caudalis amplifies pain signals traveling to higher brain centers. This central sensitization explains why migraine sufferers develop allodynia (pain from normally painless stimuli like touching the scalp) during attacks.

The evidence that CGRP is the primary mediator came from intravenous CGRP infusion studies showing it could trigger migraine-like attacks in susceptible individuals, and from the observation that CGRP levels are elevated in jugular venous blood during spontaneous migraine attacks.

The Drug Classes: Antibodies and Gepants

Two classes of CGRP-targeting drugs have reached the market, working through different mechanisms and administration routes.

Monoclonal Antibodies (Injectable, Preventive)

Four monoclonal antibodies target the CGRP pathway for migraine prevention:

• Erenumab (Aimovig) targets the CGRP receptor itself. Monthly subcutaneous injection. The only antibody that blocks the receptor rather than the peptide.
• Fremanezumab (Ajovy) binds CGRP directly. Monthly or quarterly subcutaneous injection.
• Galcanezumab (Emgality) binds CGRP directly. Monthly subcutaneous injection.
• Eptinezumab (Vyepti) binds CGRP directly. Quarterly intravenous infusion.

Diener and colleagues summarized meta-analytic efficacy data for all four in a 2026 review based on International Headache Society guidelines.^[1] Monthly migraine day reductions versus placebo: eptinezumab 0.7-3.2, fremanezumab 1.3-3.8, galcanezumab 1.1-3.7, and erenumab 1.0-2.5. For comparison, traditional oral prophylactics reduce migraine days by 0.4 (flunarizine) to 1.4 (topiramate). All four antibodies are effective in both episodic and chronic migraine, including patients who failed previous oral prophylactics.

Gepants (Oral/Nasal, Acute and Preventive)

Gepants are small-molecule CGRP receptor antagonists:

• Rimegepant (Nurtec ODT) is dual-approved for both acute treatment and prevention. Oral dissolving tablet.
• Ubrogepant (Ubrelvy) is approved for acute treatment. Oral tablet.
• Atogepant (Qulipta) is approved for prevention. Daily oral tablet. Reduces migraine days by 0.7-2.4 per month.^[1]
• Zavegepant (Zavzpret) is approved for acute treatment. Intranasal spray.

The gepant class addresses patients who prefer oral medication or need acute treatment options alongside prevention. For a detailed comparison of these drug mechanisms, see our article on how anti-CGRP drugs stop migraines.

Long-Term Effectiveness: The 2-Year Data

The largest question for any new drug class is durability. Do anti-CGRP drugs maintain their efficacy over time, or do patients develop tolerance?

The EUREkA cohort, a prospective multicenter European registry, provided the most comprehensive answer to date.^[2] Of 1,340 patients who reached the 24-month mark, 60.4% achieved at least a 50% reduction in monthly headache days. The median baseline headache frequency was 20 days per month (severe chronic migraine). Among patients assessed at all four time points (6, 12, 18, and 24 months), 53.8% showed sustained response across three or more time points.

The study also identified factors that predicted discontinuation due to lack of effectiveness: higher baseline headache days, migraine with aura, depression, and obesity. These findings provide actionable clinical guidance for setting patient expectations.

Real-World Persistence and Satisfaction

Clinical trial populations are selected and monitored. What happens in routine practice?

The Migraine Signature Study tracked 4,683 patients prescribed anti-CGRP antibodies in a large US healthcare network (Sutter Health).^[3] Among patients with dispensing data, 90.2% continued for at least 2 months, 73.7% for 6 months, and 54.7% for 12 months. These persistence rates exceeded expectations for a preventive therapy class.

Patient-reported outcomes painted a clear picture of the responder/non-responder divide. Among current users versus those who had discontinued: 62.1% versus 17.5% reported greater reduction in attacks, 62.1% versus 18.0% reported improved ability to function, and 62.4% versus 17.5% reported better quality of life. The data suggests that patients who respond to anti-CGRP therapy tend to respond well, while those who do not respond within the first few months are unlikely to benefit from continued treatment.

Beyond CGRP Blockade: Anti-Inflammatory Effects

An unexpected finding has emerged from clinical monitoring: anti-CGRP antibodies may do more than block a single peptide's action.

Ceccardi and colleagues measured plasma cytokine levels in migraine patients before and during galcanezumab treatment.^[4] Episodic migraine patients had elevated baseline levels of IFN-gamma, IL-1beta, IL-6, and IL-10 compared to both chronic migraine patients and healthy controls. At peak serum galcanezumab concentration (5 days post-injection), significant reductions in IFN-gamma, IL-1beta, IL-10, and TNF-alpha were observed, though IL-6 was unchanged.

This suggests CGRP signaling directly modulates broader inflammatory pathways, and that blocking CGRP has anti-inflammatory effects beyond preventing migraine pain. If confirmed in larger studies, inflammatory cytokine profiles could serve as biomarkers for predicting which patients will respond to anti-CGRP therapy, and the anti-inflammatory properties could have implications for conditions beyond migraine.

Safety: What the Pharmacovigilance Shows

Chen and Li analyzed the FDA Adverse Event Reporting System (FAERS) database for all four marketed gepants from January 2020 to March 2025.^[5] Their analysis identified 84 adverse event signals for rimegepant, 55 for ubrogepant, 80 for atogepant, and 31 for zavegepant.

Nausea was the only adverse event common to all four gepants (4.07-5.2%). Beyond that, the profiles diverged by route of administration. Oral gepants (rimegepant, ubrogepant, atogepant) primarily showed gastrointestinal and nervous system effects, including constipation (atogepant showed the strongest signal with a reporting odds ratio of 11.39) and dizziness. Intranasal zavegepant was associated with respiratory effects, notably nasal discomfort (reporting odds ratio 718.38, reflecting the route-specific nature of this effect).

The FDA updated safety labeling for all CGRP-targeting drugs in March 2025 to include potential for developing or worsening hypertension and Raynaud's phenomenon. For erenumab specifically, constipation was added. These are biologically plausible: CGRP is a potent vasodilator, so blocking it could reduce vasodilatory tone.

The monoclonal antibodies have accumulated longer safety records. Their most common adverse events are injection site reactions (3-6%), with serious adverse events occurring at rates comparable to placebo in clinical trials.^[1]

The Bigger Picture: Peptide Science Validated

The CGRP story represents the most complete example of the peptide drug development pipeline:

1. A peptide is identified as a disease mediator (CGRP in migraine, 1980s-1990s)
2. The receptor and signaling pathway are characterized (CGRP receptor complex, CLR/RAMP1)
3. Proof-of-concept demonstrates that blocking the peptide prevents disease (CGRP antibody trials, 2004-2017)
4. Multiple drug modalities reach the market (four antibodies + four gepants, 2018-2023)
5. Real-world data confirms durability and safety (EUREkA 2-year data, Migraine Signature Study, FAERS analysis)

This pipeline took over 30 years from initial CGRP characterization to the first FDA approval (erenumab, 2018). The lengthy timeline reflects the challenges of peptide drug development generally: identifying the right target, engineering stable molecules, and conducting adequate clinical trials. But the result, eight approved drugs that have transformed migraine treatment for millions, validates the investment. Similar pipelines are now advancing for other peptide targets in pain, including conotoxin-derived analgesics and venom-derived peptide painkillers.

The Bottom Line

CGRP drives migraine through vasodilation, neurogenic inflammation, and central sensitization in the trigeminovascular system. Eight drugs targeting CGRP or its receptor are now approved, with anti-CGRP antibodies reducing migraine days by 0.7-3.8 per month and maintaining efficacy at 2 years (60.4% responder rate in the EUREkA cohort). Real-world data shows 75% persistence at 6 months and meaningful improvements in function and quality of life. Emerging evidence suggests anti-CGRP drugs also modulate inflammatory cytokines beyond CGRP blockade. Safety profiles are favorable, with nausea the most common shared adverse event across gepants and injection site reactions the main concern for antibodies.

Frequently Asked Questions

What is CGRP and how does it cause migraines?

Calcitonin gene-related peptide (CGRP) is a 37-amino-acid neuropeptide released from trigeminal nerve fibers during migraine attacks. It dilates meningeal blood vessels (causing pulsating headache), triggers neurogenic inflammation around pain receptors, and amplifies pain signals in the brain (central sensitization). Intravenous CGRP can trigger migraine-like attacks in susceptible people, confirming its causal role.

How effective are anti-CGRP migraine drugs?

Anti-CGRP monoclonal antibodies reduce monthly migraine days by 0.7-3.8 depending on the specific drug and migraine type, compared to 0.4-1.4 for traditional oral prophylactics like beta-blockers and topiramate. In the largest long-term study (EUREkA, n=1,340), 60.4% of patients achieved at least 50% fewer headache days at 2 years. All four antibodies work even in patients who failed previous preventive medications.^[1][2]

What is the difference between CGRP antibodies and gepants?

CGRP antibodies (erenumab, fremanezumab, galcanezumab, eptinezumab) are injectable proteins given monthly or quarterly for migraine prevention. Gepants (rimegepant, ubrogepant, atogepant, zavegepant) are small-molecule CGRP receptor blockers available as oral tablets or nasal spray, used for both acute treatment and prevention. Antibodies have longer duration and simpler dosing; gepants offer oral convenience and can treat attacks as they occur.^[1]

Do anti-CGRP drugs keep working long-term?

Yes. The EUREkA European registry followed 1,340 migraine patients for 2 years and found 60.4% still had at least 50% fewer headache days at month 24. Among patients assessed at all four time points, 53.8% showed sustained response across three or more evaluations. US real-world data showed 75% of patients continued therapy at 6 months and 55% at 12 months.^[2][3]

What are the side effects of CGRP migraine drugs?

For antibodies, injection site reactions (3-6%) are most common, with serious adverse events at placebo-comparable rates. For gepants, nausea occurs in 4-5% of patients across all four drugs. Atogepant has a stronger constipation signal, and intranasal zavegepant causes nasal discomfort. The FDA in 2025 added warnings about potential worsening of hypertension and Raynaud's phenomenon for all CGRP drugs, which is biologically expected since CGRP is a vasodilator.^[5]

Do anti-CGRP drugs reduce inflammation beyond blocking migraine pain?

Emerging evidence suggests yes. A 2026 study found that galcanezumab reduced plasma levels of inflammatory cytokines IFN-gamma, IL-1beta, and TNF-alpha in episodic migraine patients at peak serum concentration. This suggests CGRP signaling modulates broader inflammatory pathways, and blocking it has anti-inflammatory effects beyond preventing migraine-specific pain. This finding could help predict treatment response and expand therapeutic applications.^[4]