15 January 2020

New treatment hopes for migraine

Clinical Drugs Neurology

The future of migraine treatment looks bright, thanks to the rapidly growing number of therapies designed specifically for the condition, say migraine experts.

These exciting new drugs and devices have emerged in recent years thanks to major leaps in our understanding of migraine pathophysiology, writes Michael Eller in a recent MJA review.

Now these were finally making their way “from bench to bedside”, the Monash Medical Centre neurologist said.

Migraines affect more than one billion people globally, and are the second-most common cause of time lost to disability. But the condition is underdiagnosed and undertreated, and, until recently, the only treatments available to patients were drugs originally designed for other conditions.

But in late 2018, the Australian regulator approved erenumab, the first monoclonal antibody specifically designed for patients who experience migraines. Two similar drugs were approved late last year.

“Efficacy among these drugs in episodic and chronic migraine is comparable, while advantages over older drugs include favourable side-effect profile, lack of drug interactions and contraindications,” Eller wrote.

The drugs work by targeting the small peptides that mediate some of the trafficking between neurons in the brain network. When this malfunctions, migraines can occur. These drugs target one of these peptides in particular, the calcitonin gene-related peptide (CGRP).

People who are experiencing a migraine have higher levels of CGRP in the jugular vein than when they are pain free, and giving people an infusion of CGRP can provoke attacks in people who suffer from migraine, scientists have found.

In one study of people with episodic migraines, treatment with 140mg of erenumab led to 3.7 fewer migraine days, down from a baseline of 8.3 per month. Those taking a placebo had 1.8 fewer migraine days.

More than 40% of patients taking the drug experienced a reduction of 50% or more in the average number of migraine days per month, compared with only 27% of the placebo group.

And even more therapies were expected to be available in the next few years, thanks to a growing understanding of the biology of migraine, Eller said.

“These include serotonin 1F receptor agonists, glutamate and orexin receptor antagonists, and molecules that work on acid-sensing ion channel type 1,” he wrote. “Monoclonal antibodies against the pituitary adenylate cyclase-activating peptide ligand and receptor, a peptide neurotransmitter that can be co-localised with CGRP (with which it shares some characteristics) is undergoing phase 2 trials.”

Some devices with promising results include a supraorbital transcutaneous stimulator, an extrinsic hand-held vagal nerve stimulator and a handheld single-pulse transcranial stimulator.

“We are in a kind of golden age for new therapies,” Brain Foundation spokesman Carl Cincinnato told The Medical Republic. “[This] should provide hope for millions of people that are living and struggling with frequent migraine attacks.”

But Cincinnato fears that without PBS approval, these new drugs will potentially be out of reach of most migraine sufferers. At the moment, patients can only buy the monoclonal antibody drugs on a private prescription, to a cost of around $800 per month.