Trial of Galcanezumab in Prevention of Episodic Cluster Headache

Background: Episodic cluster headache is a disabling neurologic disorder that is characterized by daily headache attacks that occur over periods of weeks or months. Galcanezumab, a humanized monoclonal antibody to calcitonin gene-related peptide, may be a preventive treatment for cluster headache.

Methods: We enrolled patients who had at least one attack every other day, at least four total attacks, and no more than eight attacks per day during a baseline assessment, as well as a history of cluster headache periods lasting at least 6 weeks, and randomly assigned them to receive galcanezumab (at a dose of 300 mg) or placebo, administered subcutaneously at baseline and at 1 month. The primary end point was the mean change from baseline in the weekly frequency of cluster headache attacks across weeks 1 through 3 after receipt of the first dose. The key secondary end point was the percentage of patients who had a reduction from baseline of at least 50% in the weekly frequency of cluster headache attacks at week 3. Safety was also assessed.

Results: Recruitment was halted before the trial reached the planned sample size of 162 because too few volunteers met the eligibility criteria. Of 106 enrolled patients, 49 were randomly assigned to receive galcanezumab and 57 to receive placebo. The mean (±SD) number of cluster headache attacks per week in the baseline period was 17.8±10.1 in the galcanezumab group and 17.3±10.1 in the placebo group. The mean reduction in the weekly frequency of cluster headache attacks across weeks 1 through 3 was 8.7 attacks in the galcanezumab group, as compared with 5.2 in the placebo group (difference, 3.5 attacks per week; 95% confidence interval, 0.2 to 6.7; P = 0.04). The percentage of patients who had a reduction of at least 50% in headache frequency at week 3 was 71% in the galcanezumab group and 53% in the placebo group. There were no substantial between-group differences in the incidence of adverse events, except that 8% of the patients in the galcanezumab group had injection-site pain.

Conclusions: Galcanezumab administered subcutaneously at a dose of 300 mg once monthly reduced the weekly frequency of attacks of episodic cluster headache across weeks 1 through 3 after the initial injection, as compared with placebo. (Funded by Eli Lilly; ClinicalTrials.gov number, NCT02397473.).