Effect of Sildenafil in Individuals With Migraine Pretreated With Erenumab (COMPETE)

Inclusion Criteria: Participant has provided informed consent prior to initiation of any study-specific activities/procedures. Age ≥18 years upon entry into screening. History of migraine without aura for ≥12 months with a frequency of 1-5 migraine attacks per month before screening according to the International Headache Society (IHS) Classification ICHD-3 (Headache Classification Committee of the International Headache Society, 2018), based on medical records and/or patient self-report. Exclusion Criteria: History of any primary headache disorder other than migraine without aura, or tension-type headache with a frequency of ≥5 headache days per month before screening according to the International Headache Society (IHS) Classification ICHD-3 (Headache Classification Committee of the International Headache Society, 2018), based on medical records and/or patient self-report. History of any secondary headache disorder before screening according to the International Headache Society (IHS) Classification ICHD-3 (Headache Classification Committee of the International Headache Society, 2018) based on medical records and/or patient self-report. Intake of prophylactic migraine medication within ≤30 days or 5 plasma half-lives (whichever is longer) prior to screening. Prior intake of therapies targeting the CGRP signaling pathway, including anti-CGRP ligand monoclonal antibodies, anti-CGRP receptor monoclonal antibodies, and small molecule CGRP receptor antagonists. The participant is at risk of self-harm or harm to others as evidenced by past suicidal behavior. History or evidence of any other clinically significant disorder, condition, or disease (with the exception of those outlined above) that, in the opinion of the investigator will pose a risk to participant safety or interfere with the study evaluation, procedures or completion. Female participants of childbearing potential with a positive pregnancy test assessed at screening or day 1 by a urine pregnancy test. Female participants who are pregnant or breastfeeding or plan to become pregnant or breastfeed during participation in the study. Evidence of current pregnancy or breastfeeding per participant self-report or medical records. Participants likely to not be available to complete all protocol-required study visits or procedures, and/or to comply with all required study procedures to the best of the participants' and investigator's knowledge.