Efficacy and safety of galcanezumab as chronic cluster headache preventive treatment under real world conditions: Observational prospective study

Background Calcitonin gene-related peptide has shown to play a central role in cluster headache (CH) pathophysiology. A clinical trial with galcanezumab was carried out in chronic cluster headache (CCH) but did not meet its primay endpoint. However, its off-label use in patients with CCH refractory to other therapies could be considered. We aimed to asses the efficacy and safety of galcanezumab as CCH preventive treatment in a real-life setting. Methods An observational study was conducted. Patients with CCH who received at least one dose of 240 mg of galcanezumab. Results Twenty-one patients who tried a mean of 6.3 ± 1.9 preventive therapies, including onabotulinumtoxinA in 90.5%. At baseline, the median of frequency was 60 (37.5–105) monthly attacks with 10 (8.3–10) points in pain intensity (Numerical Rating Scale). After one month, the frequency decreased to 31 (10.5–45) ( p = 0.003) with 8.5 (8–9.5) intensity ( p = 0.007); 10 (47.6%) patients were 50% responders of whom four (19%) were 75% responders. Of the 15 patients with 3 months of follow-up, seven (46.6%) reduced their frequency by 50% and four (26.6%) by 75%, with 40 (10–60) monthly attacks ( p = 0.07) and pain intensity of 8 (5–10) ( p = 0.026). Some 52% patients experienced adverse events, mostly mild. Conclusions In our cohort of refractory CCH, galcanezumab was effective in almost 50% of patients. This finding supports individual off-label treatment attempts.