Role Of CGRP and Antagonists In Migraine Attack (1)
CGRP is critically implicated in the occurrence and unfolding or progress of a migraine attack. CGRP or Calcitonin gene-related peptide is a powerful protein/peptide containing a short chain of amino acid monomers. It plays a critical role in transmitting pain signals through the body in events such as migraines. It is also involved in the vasodilation, inflammation, immune-modulatory responses among others during migraine attack apart from increasing heart beat and altering sensory transmission.
CGRP is produced by the peripheral and central neurons of our central nervous system specifically around the spinal cord and the trigeminal ganglion. Prior to and during migraine episodes, the central and peripheral neurons release more CGRP. This is then mediated through CGRP receptors (CALCRL and RAMP1) found throughout the body. One way to prevent pain from occurring is to block the receptors that receive the CGRP protein using a chemical/drug. Such drugs are called CGRP antagonists or CGRP blockers.
In a post of March 28th, 2012 I had written (‘CGRP Blockers & SRAs – The New Faces In Research For Migraine Management’) on work being done on drugs that targeted CGRP receptors but were abandoned after Phase III trials due to adverse reaction found in some of the trial population. (2).
Currently, two studies showing work with calcitonin receptor blockers have moved into Phase II trials. This means that though positive outcomes have been had from these researches involving smaller populations, larger studies are required to clear the drug for sale or prescription.
This involves a prospective drug that aims to prevent migraine from starting rather than trying to stop attack from progressing once it has begun. The drug involves monoclonal antibodies or antibodies that are identical immune cells – clones of their unique parent cell. Such monoclonal antibodies are being directed at the CGRP to target the protein.
This research examined 163 migraineurs for a period of six months, who had migraine attacks ranging anything from 5 -14 days every month. In this time, they gave the population either a placebo or the drug under study called ALD403 without the migraineurs knowing what they were taking. Those who took the drug reported a 66% reduction in number of migraine days and in 12 weeks time reported to be migraine-free.
As per lead author Peter Goadsby, MD, PhD, of the UC San Francisco and a member of the American Academy of Neurology, “These results may potentially represent a new era in preventive therapy for migraine. Migraine remains poorly treated, and there are few effective and well tolerated treatments approved that prevent attacks from occurring.” (3)
This potential drug in injectable form too is a preventative rather than a mitigator of migraine condition and is based on monoclonal antibodies targeting CGRPs. In Phase II trials as well, the research studied 217 migraineurs who experienced anything from 4-17 days of migraine days every month.
The population being observed was also administered either a placebo or the drug under study called LY2951742 via the subcutaneous injection route, without being told which was which for a period of three months. Those who were receiving the real drug reported more than 4 days less of migraine days in a month. However, they also experienced more side-effects such as abdominal pain and upper respiratory tract infections.
As per Dr. David Dodick, MD, of Mayo Clinic Arizona in Phoenix and a member of the American Academy of Neurology, “We’re cautiously optimistic that a new era of mechanism-based migraine prevention is beginning. There is a huge treatment need for migraine — the third most common and seventh most disabling medical disorder in the world” (4)
- Image Credit: The Role of CGRP and its Antagonists in Migraine- Peripheral Actions of CGRP: Neurogenic Inflammation; Flipper.diff.org; Web April 2014; http://bit.ly/PsCR7O
- CGRP Blockers & SRAs – The New Faces In Research For Migraine Management; Web April 2014; https://migrainingjenny.wordpress.com/2012/03/28/cgrp-blockers-sras-the-new-faces-in-research-for-migraine-management/
- New drugs offer hope for migraine prevention; ScienceDaily News; Web April 2014; http://www.sciencedaily.com/releases/2014/04/140422162048.htm
- Stopping Migraines Before They Start; DailyRx.com; Web April 2014; http://www.dailyrx.com/migraine-patients-had-fewer-attacks-monoclonal-antibody-treatment
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