The drug, a humanized monoclonal antibody that binds to calcitonin gene-related peptide (CGRP), is administered by self-injection in 300-mg doses.
Galcanezumab is the first medication for episodic cluster headache that reduces the frequency of attacks, the agency said in an announcement.
Cluster headache can be more intense than migraine. The pain is unilateral and occurs in the orbital, supraorbital, or temporal regions. It reaches its peak intensity within 5-10 minutes and generally lasts for 30-90 minutes. Symptoms include a burning sensation, conjunctival injection, rhinorrhea, and photosensitivity. Patients often have one to three of these headaches per day, and the headaches appear to be linked to the circadian rhythm. An episodic cluster cycle can last for weeks to months of daily or near daily attacks.
A study presented at the recent meeting of the American Academy of Neurology provided evidence of the drug’s efficacy in cluster headache. In this trial, researchers randomized 106 patients with episodic cluster headache to galcanezumab or placebo. The baseline cluster headache frequency was 17.3 attacks per week, and galcanezumab reduced this frequency to 9.1 attacks per week, compared with 12.1 attacks per week with placebo. The most common side effect reported in this and other clinical trials was injection-site reactions.
Galcanezumab entails a risk of hypersensitivity reactions, according to the FDA. These reactions may occur several days after administration and may be prolonged. “If a serious hypersensitivity reaction occurs, treatment should be discontinued,” the agency said.
“It’s a very exciting day. There had never been a drug approved for prevention of cluster headache,” said Stewart J. Tepper, MD, professor of neurology at the Geisel School of Medicine at Dartmouth and director of the Dartmouth Headache Center, Dartmouth-Hitchcock Medical Center, Lebanon, N.H.
Bruce Jancin/MDedge News
Dr. Stewart J. Tepper
It is difficult to achieve therapeutic concentrations of current preventive medications that do not have FDA approval for this indication, such as verapamil, lithium, or antiepileptic drugs. Galcanezumab, in contrast, works quickly. It is important to note that the approval was for preventive treatment of episodic cluster headache, not for prevention of chronic cluster headache, and not for acute treatment, Dr. Tepper said.
“It’s important to get optimal therapy for cluster headache. It is one of the most disabling, terrible disorders on Earth,” Dr. Tepper said. “The importance [of this approval] cannot be overestimated.”
When asked for comment, Alan M. Rapoport, MD, clinical professor of neurology at the University of California, Los Angeles, said “If this monoclonal antibody to the CGRP ligand works as well in real life as in the trial, it will be an important advance in the treatment of cluster headache.”
Prior to the approval of galcanezumab, noninvasive vagal nerve stimulation was approved in November 2018 for adjunctive use in the preventive treatment of cluster headache in adults.
The FDA granted the application for galcanezumab using a Priority Review and Breakthrough Therapy designation. The agency approved galcanezumab for the preventive treatment of migraine in adults in September 2018. The drug appears to have a similar safety profile in both patient populations. Eli Lilly, which is based in Indianapolis, Indiana, manufactures the drug.
This article was updated June 5, 2019.