Abstract text (incl. figure legends and references)

Question: Calcitonin gene-related peptide(CGRP) has shown to play a pivotal role in cluster headache(CH) pathophysiology. A clinical trial with Galcanezumab has been carried out in chronic cluster headache(CCH) that did not achieve significant reduction of headache attacks. However, its off-label use in patients with CCH refractory to other therapies could be considered.We aim to asses the efficacy and security of Galcanezumab as preventive treatment in a CCH population in a real-life setting.

Methods: Observational prospective study. CCH patients who received at least 1 administration of 240mg monthly subcutaneous Galcanezumab. Data were obtained from clinical interviews, headache diaries, dissability scales and PGIC score.

Results: 21 patients, 76.2% males, mean age of 47.8 years with 12.2 years of CH. 6.3±1.9 previous preventive therapies, incluiding onabotulinumtoxinA in 90.5%. Furthermore, occipital neuroestimulation in 38.1%, occipital radiofrequency in 9.5% and GON section in 4.8%. The average number of attacks per month was 76.6±61.1 with 8.9±1.5 intensity (NRS) at baseline. After one month of treatment number of attacks reduced to 34.7±25.3 with 8.1±17 intensity; 10(47.6%) patients achieved a reduction of at least 50% in monthly headache attacks, of which 4(19%) achieved a 75% reduction. Triptans abusers reduced from 61.9% to 33.3%. Of the 15 patients of whom we have 3 months follow-up, 7(46.6%) reduced their monthly attacks by 50% and 4(26.6%) 75%, with an average of attacks/month of 35.9±28.1 and an intensity of 7.5±2.3. Triptans abusers were 26.6%. 47.6% considered the improvement as a real difference in their lives (PGIC≥5) after 1 dose of Galcanezumab and 60% after 3 doses. 52% experienced adverse events, mostly mild, most common constipation(19%) leading to discontinuation in 1 patient.

Conclusions: Despite how refractory our CCH cohort is, Galcanezumab was effective in nearly 50% patients. This supports individual off-label treatment attempts.