CGRP Monoclonal Antibody Treatment
CGRP Monoclonal Antibodies (CGRP MABs) are a type of medication that have been developed to address an unmet need in the treatment of migraine. CGRP mabs are approved in Ireland only for chronic migraine. It is hoped that they will provide a tolerable and effective method for treatment of migraine, which it is hoped in turn will provide for a better quality of life in people who live with migraine.
NOTE: The information contained in this factsheet is for information only and not intended to replace medical advice or diagnosis.
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What is CGRP?
CGRP (calcitonin gene related peptide) is the name of a brain chemical. It is released into the blood system in response when something triggers the nerves in the brain (trigeminal nerves) that are associated with a migraine attack.
When it is released, it causes a cascade of events, for example the widening of blood vessels and inflammation among other reactions in the brain. The results in the person experiencing head pain and the other symptoms of migraine.
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What are Monoclonal Antibodies?
Our immune system protects us from infections . Antibodies are part of our immune system. They are made by our blood cells. When an infection is detected, our white blood cells release millions of antibodies cloned to fight the specific infection. This happens anytime we have an infection, such as a viral illness. Our natural antibodies are able to target lots of different types of infectious cells, so they are called POLYclonal antibodies.
Scientists studying this response in the body have developed MONOclonal antibodies. These antibodies are developed in a lab and are designed to perform a specific action in the same way our body’s natural POLYclonal antibodies work. Our natural antibodies are called Polyclonal antibodies because they can clone to target many types of infection. MONOclonal antibodies are designed to have a specific target action in the body. They are used to treat many conditions for example, Asthma, Cancer, High Cholesterol and Osteoporosis.
CGRP Monoclonal Antibodies (MABs) target and block the CGRP cells from going into action when they are released by the brain in response to the triggering of a migraine. So, the Monoclonal antibodies stop or block the CGRP cells from going in action. Therefore, they stop the cascade of events that is set into action that causes a migraine attack and symptoms. CGRP Monoclonal antibodies can stay working in the body for a couple of weeks. This is how they can prevent migraine, when topped up. It is hoped that after a course of Monoclonal Antibody treatment, the brain will be less at risk of migraine attacks in the long term by itself.
What is CGRP?
There are currently 4 of these Anti-CGRP MABs available to patients in Ireland, available through two methods:
Sub-Cutaneous Injection (an small injection into the tissues just under the skin)
Intravenous Infusion ( A drip given through a cannula in the arm that takes 30 minutes.)
| CGRP Compound | Brand Name | Administered |
|---|---|---|
| Erenumab | Aimovig | Subcutaneous Injection once a month |
| Fremanezumab | Ajovy | Subcutaneous injection once a month or quarterly |
| Galcanezumab | Emgality | Subcutaneous injection once a month |
| Eptinezumab | Vyepti | Intravenous Infusion once every 3 months |
Erenumab, Fremanezumab and Galcanezumab are all available for reimbursement under the High-Tech Arrangement and Eptinezumab is available under Hospital Pricing Approval. These are both covered by a Managed Access Protocol (MAP) which outlines the criteria patients must meet before they are recommended for these medications.
From the HSE MAP – ‘Approval for reimbursement will be confined to consultant neurologists registered with the Irish Medical Council, who have agreed to the terms of this MAP and have been approved by the HSE. Applications for reimbursement approval will only be considered from these prescribers.’
What this means is that Anti CGRP MABs are available only by prescription from a consultant Neurologist, to a person who has tried 3 other types of preventative treatment that haven’t helped reduce their migraine attacks. There are other suitability criteria to be considered in the prescribing of these medications, which will be assessed by your doctor.
Important!
Anti- CGRP mAB are a new treatment, and we are still learning about them. They are at present believed to be well tolerated. The most common side effects reported are mild injection site reactions (such as pain, swelling and skin reactions), constipation, itching and cramps/ muscle spasms. It is always important to discuss medication, side-effects, and concerns with your doctor at the beginning and throughout your treatment. Keeping a headache diary can help you to communicate your experiences with your doctor.
Gepants:
While the injectable forms of these medications are effective and work very well for many, not everyone responds to them. There are other formats in the pipeline, one of which is Rimegepant. This medication like Erenumab, binds to the receptor and blocks the CGRP from making contact with it.
It is currently under review for reimbursement by the HSE for both Acute and Preventative treatment.
It is only available on prescription from a GP or Neurologist and sold privately in pharmacies. As it is not yet reimbursed, it does not fall under any of the drugs payment schemes. A decision on reimbursement is awaited from the HSE.
Like Anti-CGRP MABs, Gepants are a new medication that we are still learning about, and the same guidance to discuss side effects, reactions and other concerns before and throughout your treatment is important.
References:
Monoclonal Antibodies to CGRP or Its Receptor for Migraine Prevention (sciencedirectassets.com)
Calcitonin Gene-Related Peptide (CGRP) monoclonal antibodies – The Migraine Trust
Antibodies: Definition, Types & Function (clevelandclinic.org)
Blocking CGRP in migraine patients – a review of pros and cons | The Journal of Headache and Pain | Full Text (biomedcentral.com)
European Headache Federation guideline on the use of monoclonal antibodies targeting the calcitonin gene related peptide pathway for migraine prevention – 2022 update | The Journal of Headache and Pain | Full Text (biomedcentral.com)