OBJECTIVE: A phase 2, double-blind, placebo-controlled study to evaluate the 
efficacy and safety of erenumab for the prevention of episodic migraine in 
Japanese patients was conducted.
BACKGROUND: Previous global clinical studies have demonstrated the efficacy of 
erenumab in the prevention of migraine.
METHODS: Patients were randomized to placebo or erenumab 28, 70, or 140 mg 
administered subcutaneously once per month for 6 months. The primary endpoint 
was change from baseline in mean monthly migraine days over months 4-6 of the 
double-blind treatment phase. Secondary endpoints included the proportion of 
patients achieving ≥50% reduction from baseline in mean monthly migraine days 
(≥50% response) and change from baseline in mean monthly acute migraine-specific 
medication treatment days (MSMD) and mean Headache Impact Test (HIT-6™) scores. 
Efficacy outcomes were also determined at months 1, 2, and 3.
RESULTS: Four hundred and seventy five patients were randomized 2:1:2:2 to 
placebo and erenumab 28, 70, and 140 mg, respectively. Greater reductions in 
monthly migraine days were observed for erenumab vs placebo with differences of 
-1.25 (95% CI: -2.10 to -0.41; P = .004), -2.31 (95% CI: -3.00 to -1.62; 
P < .001), and -1.89 (95% CI: -2.58 to -1.20; P < .001) days for erenumab 28, 
70, and 140 mg. The odds of having a ≥50% response were 3.2, 5.6, and 4.7 times 
greater for erenumab 28 mg (95% CI: 1.30-7.88; P = .009), 70 mg (95% CI: 
2.60-12.06; P < .001), and 140 mg (95% CI: 2.24-9.99; P < .001) than for 
placebo. Greater reductions from baseline in mean acute monthly MSMD were 
observed for erenumab vs placebo with differences of -1.07 (95% CI: -1.80 to 
-0.35; P = .004), -2.07 (95% CI: -2.66 to -1.49; P < .001), and -2.04 (95% CI: 
-2.63 to -1.45; P < .001) days for erenumab 28, 70, and 140 mg. Erenumab 70 and 
140 mg also resulted in greater improvements in HIT-6™ scores. The safety 
profile was similar across treatment groups. The most common adverse event was 
nasopharyngitis, which occurred in 29.4% of patients in the placebo group and 
28.9%-33.3% of patients in the erenumab groups.
CONCLUSION: Monthly subcutaneous injections of erenumab 70 mg demonstrated 
statistically significant and numerically maximal efficacy with a favorable 
safety profile, suggesting that erenumab is a potential new therapy for migraine 
prevention in Japan.