Objective: To investigate the efficacy and safety of mirogabalin, an α2δ ligand, in patients with fibromyalgia (FM). Methods: In three 13-week, multicenter, double-blind, phase 3 studies (studies A, B, and C), patients with FM (n = 1293, 1270, and 1301, respectively) were randomized (1:1:1:1) to placebo, pregabalin 150 mg twice daily, mirogabalin 15 mg once daily or mirogabalin 15 mg twice daily. The primary endpoint was the change in weekly average daily worst pain score (ADPS) at week 13. Key secondary endpoints included Patient Global Impression of Change and change in the Fibromyalgia Impact Questionnaire total score. Long-term safety of mirogabalin was assessed in a 52-week extension study. Results: Neither mirogabalin dose demonstrated a significant ADPS reduction from baseline vs. placebo at week 13 in any of the three studies. Pregabalin significantly reduced ADPS from baseline vs. placebo in studies B and C (p = .0008 and .0001, respectively). The effect of mirogabalin compared with placebo on key secondary endpoints was variable across the studies. Mirogabalin was well tolerated by most patients in the phase 3 studies; no unexpected adverse events occurring during the 52-week extension study. Conclusion: While both mirogabalin doses were well tolerated by most patients and showed potential for reducing pain associated with FM, the primary endpoint of significant pain reduction in patients on mirogabalin compared with placebo was not achieved in any of the three randomized controlled studies. Clinical trial registration: NCT02146430; NCT02187159; NCT02187471; and NCT02234583 (extension study).
Keywords: Fibromyalgia; mirogabalin; pain; pregabalin; randomized controlled trial.