Efficacy of Erenumab in Chronic Cluster Headache

Inclusion Criteria (screening) * Adults ≥18 and \< 65 years of age * Documented history of chronic cluster headache for ≥12 months prior to screening according to the International Classification of Headache Disorders-3rd Edition (ICHD-3) * Participants are able to distinguish cluster headache attacks from other headaches. * Insufficient efficacy OR tolerability OR contraindications of approved cluster headache prophylactic medications. Insufficient efficacy and tolerability as determined by the patient. * Sufficient acute attack treatment with triptans or oxygen based on the patient´s history * The patient is able to distinguish cluster headache attacks from other headaches (i.e. tension-type headaches). Inclusion Criteria (Baseline) * At least 9 cluster headache attacks as defined by the ICHD-3 in 7 days during the baseline epoch (SPII), confirmed by patient-reported eDiary entries. * Attacks must have occurred on more than 50% of days of the baseline epoch (SPII). * ≥ 90% patient-reported eDiary compliance during the Baseline epoch, compliance is measured as interacting with e-Diary at least once a day. Exclusion Criteria: * Diagnosis or history of other primary headache diseases according to the International Classification of Headache Disorders, 3rd Edition (ICHD-3), excluding episodic tension type headache and migraine as defined in criterion 2. * Headache freedom from the historic diagnosis of migraine has to be at least one year prior to study inclusion. If patients have on average \<=1 migraine attack per month within a year and can distinguish between migraine attacks and cluster attacks, they are allowed to participate. * Unable to differentiate cluster headache attacks from other headaches * Use of a prophylactic cluster headache medication within 5 half-lives prior to the start of the baseline phase * Parallel use of an SPG stimulator, deep brain stimulation or parallel use of a device for the acute/preventive treatment of chronic cluster headache * Administration of botulinum toxin type A or B in the head or neck area, within 4 months of baseline (SP II) * Concurrent use of other therapeutic monoclonal antibodies. * Current use or any prior exposure to any calcitonin-gene-related peptide (CGRP) antibody, any antibody to the CGRP receptor * Use of other investigational drugs within 5 half-lives of enrollment, or until the expected pharmacodynamic effect has returned to baseline, whichever is longer * Evidence of drug, opioid or alcohol abuse o…