Galcanezumab (Emgality) was just approved by the FDA for the prevention of episodic cluster headaches. Galcanezumab is one of the three new drugs recently approved for the prevention of migraines (the other two are erenumab, or Aimovig and fremanezumab, or Ajovy). These are monoclonal antibodies (mAbs) that block CGRP, a chemical released during attacks of migraine and cluster headaches.
The manufacturer of fremanezumab also conducted trials for the prevention of cluster headaches, but could not prove that the drug was more effective than placebo. Galcanezumab was also tested for chronic cluster headaches and it did not seem to help. Only 10-15% of cluster headache sufferers have the chronic form. About 250,000 Americans suffer from cluster headaches. Compared to migraines, which affect over 35 million Americans, this is a rare disease. This makes it difficult to conduct clinical trials of new treatments. The only abortive drug approved for the treatment of an acute cluster attack is sumatriptan (Imitrex) injection.
The dose of galcanezumab for the prevention of migraines is 240 mg injection at the start and then, 120 mg every month. The dose for cluster headaches is 300 mg. Of the 106 patients in the cluster headache study only 2 stopped the drug because of side effects. Just like in migraine trials, which involved thousand of patients, the only side effect which occur in more than 2% of patients was injection site reactions, but serious allergic reaction can also occur.
Since erenumab was approved for migraines before the other two mAbs and because preliminary evidence suggested that these drugs may work for cluster headaches, we’ve tried erenumab and then, fremanezumab in our cluster patients who did not respond to usual therapy. Although our numbers are too small to make any sweeping conclusions, it appears that just like with migraines, two out of three patients obtain some benefit. Now that galcanezumab is officially approved, we will be using it for all of our cluster headache patients since insurance companies will have to pay for it. Based on our experience with these drugs in migraines, it is likely that the insurers will require that patients first try and fail some of the other preventive therapies, even if none of those have been approved by the FDA. The most commonly used drug for the prevention of cluster headaches is a blood pressure medicine in the calcium blocker family, verapamil. We also try to abort the entire cluster with an occipital nerve block or a course of prednisone, a steroid medication. Epilepsy drugs such as topiramate (Topamax) and a psychiatric drug, lithium can also help.
Cluster headaches affect more men than women and cause more severe pain than migraines, leading some to call them suicide headaches. Women do suffer from cluster headaches as well and they are more often misdiagnosed. Unfortunately men don’t fare well either – 46% of men are misdiagnosed, compared with 61% of women. It takes 5-6 years before the correct diagnosis is made. Cluster headaches are often mistaken for migraines because pain is on one side of the head and for sinus headaches because cluster headaches are usually accompanied by a runny nose.
