Abstract

• The first-choice drug for the prevention of migraine attacks is oral propranolol, taken daily. Amitriptyline and valproic acid are other options, although valproic acid must not be used in women who are or could become pregnant.
   
• Erenumab is a monoclonal antibody that binds to the CGRP receptor. CGRP is a neuropeptide that has vasodilating and gastrointestinal effects and modulates nociceptive signalling. Erenumab has been authorised in the European Union for the prevention of migraine attacks in patients who experience attacks on more than 4 days a month. It is administered monthly by subcutaneous injection.
   
• Erenumab has not been compared in head-to-head trials with other drugs used to prevent migraine attacks.
   
• Erenumab has been evaluated in four double-blind placebo-controlled trials lasting 12 or 24 weeks. They included a total of about 2700 patients who experienced migraine attacks on 8 to 18 days per month on average. These trials yielded consistent results: 30% to 50% of patients in the erenumab groups had at least a 50% reduction in the number of migraine days, versus 15% to 30% of patients in the placebo groups. Erenumab had similar efficacy after failure of another preventive drug.
   
• Few patients treated with erenumab experienced adverse effects during clinical trials. As expected, it mainly caused injection site reactions. In rare cases, erenumab provoked constipation or hypersensitivity reactions. Follow-up only lasted a few months.
   
• Given its mechanism, cardiovascular ischaemic events are likely with erenumab. Patients at high risk of cardiovascular events were excluded from the trials. The few cardiovascular events reported in patients receiving erenumab in the trials must be taken into account as safety signals.
   
• As CGRP has been suggested to play a role in uterine blood flow during pregnancy, erenumab is likely to have harmful effects during pregnancy, especially in women at risk of developing eclampsia. As a precaution, erenumab should not be used in women who are or could become pregnant.
   
•  POSSIBLY HELPFUL  In four double-blind placebo-controlled trials, erenumab noticeably reduced the number of migraine days per month for a minority of patients, including patients in whom other preventive drugs had failed. After only a few months' follow-up, few patients treated with erenumab experienced adverse effects, mainly injection site reactions and constipation. But there remain many unknowns, in particular concerning its possible cardiovascular adverse effects. In practice, when the option of pharmacological treatment is chosen to prevent migraine attacks, it appears more prudent to first use other better-established drugs. If migraine attacks remain frequent and debilitating or when these drugs cause excessive adverse effects, erenumab is an option.
  

©Prescrire 1 September 2019

"Erenumab - Aimovig°. For the prevention of migraine attacks: notable decrease in the frequency of attacks in some patients, but uncertainty over cardiovascular effects" Prescrire Int 2019; 28 (207): 201-205. (Pdf, subscribers only).

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