Cluster headache (CH) is ahighly debilitating headache disorder characterized by frequent attacks of excruciating unilateral pain accompanied by cranial autonomic symptoms. Calcitonin gene-related peptide (CGRP) is implicated in the pathophysiology of CH. Preventive efficacy and tolerability of the anti-CGRP antibody galcanezumab in patients with episodic (eCH) and chronic CH (cCH). Review of the study results and the challenges in developing drugs for the preventive treatment of CH. In two international multicenter phaseIII trials galcanezumab 300 mg given subcutaneously every 4weeks was compared with placebo. The double-blind study period (8weeks in eCH, 12weeks in cCK) was preceded by abaseline period in both trials. The primary endpoint was the reduction in weekly attack frequency. In the eCH trial, 106patients were randomized to either galcanezumab (n = 49) or placebo (n = 57). The mean weekly attack frequency during the first 3weeks decreased by 52% in the galcanezumab group compared with 27% in the placebo group (p = 0.036). In the cCH trial, 237patients were randomized to galcanezumab (n = 117) or placebo (n = 120). The primary endpoint was not met in this study. The reduction in mean weekly attack rate was 5.4 with galcanezumab versus 4.6 with placebo (p = 0.334). Galcanezumab was well tolerated in both studies. Galcanezumab had asignificant effect in the prevention of eCH attacks but not in cCH. Possible reasons for this discrepancy are discussed.
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