Galcanezumab effectiveness on comorbid cluster headache and chronic migraine: a prospective case series

Background: Cluster headache (CH) and migraine are recurrent painful primary cephalalgies, typically with different clinical appearance and some shared features, such as unilateral pain, common triggers and response to triptans and/or monoclonal antibodies against the calcitonin gene-related peptide (CGRP) pathway. Common pathophysiological mechanisms are proposed in CH and migraine, including the role of the trigeminal-vascular system with its most representative neuropeptide, CGRP. Very few case series have been conducted so far investigating anti-CGRP treatments in patients with comorbid CH and migraine, and no cases have been reported which assess both CH and chronic migraine outcomes. Case series: We describe 4 patients with both chronic migraine and cluster headache, with or without failure to preventive medications. Galcanezumab (240 mg loading dose, followed by 120 mg monthly) was used for at least a 3-month treatment, demonstrating improvement in both migraine and CH outcomes (i.e. migraine days, CH attacks, Headache Impact Test -6 item score, acute medications use), achieving sustained clinical benefit. No adverse events were reported. Discussion and conclusion: Taking into account the role of CGRP in migraine and CH pathophysiology, a usually well-tolerated treatment with CGRP blockade could be a rationale-based option to treat patients with coexisting chronic migraine and cluster headache. Additional studies are needed to assess the role of anti-CGRP drugs in episodic and chronic CH treatment, as well as to establish correct timing and patient prerequisites to begin therapy.