Aimovig is licensed for the prophylaxis of migraine in adults who have at least four migraine days per month. The recommended dose is 70mg by subcutaneous injection every four weeks increasing to 140mg (given as two 70mg injections) every four weeks if required. Aimovig is intended for administration by the patient or other individual after appropriate training.
Mode of action
Erenumab is a human monoclonal antibody that blocks the CGRP receptor, thought to be involved in the transmission of the pain signals associated with migraine. CGRP levels have been shown to increase significantly during migraine and return to normal with headache relief.
Efficacy in chronic migraine
The safety and efficacy of erenumab as monotherapy for prophylaxis of chronic migraine were assessed in a double-blind study involving 667 patients experiencing migraine with or without aura (≥15 headache days per month including ≥8 migraine days) who were randomised to receive erenumab 70mg (n=191) or 140mg (n=190) or placebo (n=286) every 4 weeks.
At week 12 the reduction in monthly migraine days was significantly greater in the erenumab groups than in the placebo group (mean change -6.6 days in both erenumab groups vs -4.2 days in the placebo group [p < 0.0001 for both]). Onset of erenumab effect was observed from the first week of administration.
The study also showed that the proportion of patients who achieved at least a 50% reduction in monthly migraine days was significantly greater with erenumab than placebo (41.2% and 39.9% of patients in the 140mg and 70mg groups, respectively, vs 23.5% of patients in the placebo group [p < 0.001 for both]).
Use in episodic migraine
In another study the use of erenumab for the prevention of episodic migraine was assessed in 955 patients with a history of migraine with or without aura for at least 12 months before screening. Eligible patients had to have had ≥ 4 and < 15 migraine days per month and < 15 headache days per month on average during the three-month period before screening. Patients were randomised to receive erenumab 70mg (n=317) or 140mg (n=319) or placebo (n=319) every four weeks for six doses.
Compared with baseline, the mean number of migraine days per month was significantly reduced from months 4 to 6 in the erenumab groups compared with the placebo group (-3.2 days and -3.7 days in the erenumab 70mg and 140mg groups, respectively versus -1.8 days in the placebo group [p < 0.001 for both]).
In addition, the proportion of patients with a 50% or greater reduction in the mean number of migraine days per month was significantly greater in the erenumab 70mg and 140mg groups compared with the placebo group (43.3% and 50%, respectively, versus 26.6% [p < 0.001 for both]).
Erenumab was well tolerated in clinical trials with most reactions mild to moderate in severity. The most commonly reported adverse events were constipation, pruritus, muscle spasm and injection site reactions.
Commenting on the launch of Aimovig, Professor Zameel Cader, Consultant Neurologist at the Oxford University Hospitals NHS Foundation Trust and the Oxford Headache Centre, said: 'Erenumab has been shown to reduce the average number of monthly migraine days in both episodic and chronic migraine patients, including those who have tried existing treatment options. Today's news represents a new approach for the clinical community in our ability to treat those that suffer most with migraine.'