OR33-6 The Neurokinin 3 Receptor Antagonist, Fezolinetant, Is Effective in Treatment of Menopausal Vasomotor Symptoms: A Randomized, Placebo-Controlled, Double-Blind, Dose-Ranging Study

Vasomotor symptoms (VMS; eg, hot flashes, night sweats) are caused by a loss of thermoregulatory control. The thermoregulatory center in the brain is innervated by kisspeptin/neurokinin B/dynorphin (KNDy) neurons. The activity of KNDy neurons is stimulated by neurokinin 3 receptor (NK3R) activation and inhibited by estrogen negative-feedback. Declining estrogen levels at menopause disturb this balance, leading to VMS. Fezolinetant is an antagonist at NK3R that acts to moderate KNDy neuron function for the treatment of VMS (1). The aim of the current trial was to evaluate fezolinetant dose levels and treatment regimen in VMS. In this phase 2b, double-blind trial (NCT03192176), menopausal women age >40−65 y with moderate/severe VMS (≥50/wk) were randomized to one of the following: fezolinetant 15, 30, 60, or 90 mg BID or 30, 60, or 120 mg QD or placebo (PBO). Coprimary efficacy outcomes were frequency and severity of moderate/severe VMS at wk 4 and 12. Secondary efficacy outcomes included changes in moderate/severe VMS frequency and severity by study wk. Of 356 women randomized, 352 received ≥1 dose study drug (safety population; mean [SD] age: 54.6 [4.7] y; 73% white) and 287 (81%) completed the study: PBO: 37/44 (84%); fezolinetant: 250/312 (80%). The most common reasons for discontinuation were withdrawal of consent (6.7%) and AEs (5.9%). All fezolinetant dose groups demonstrated reductions in VMS frequency and severity at wk 4 and 12. Significant dose responses were observed in all coprimary efficacy endpoints. The differences from PBO in least squares (LS) mean changes from baseline in moderate/severe VMS frequency per day at wk 4 were −1.9, −3.0, −2.8, and −3.5 for 15, 30, 60, and 90 mg BID, respectively, and −2.3, −3.0, and −2.4 for 30, 60, and 120 mg QD, respectively, with a common SE of 0.8 (all P<.05). The differences from PBO in LS mean change from baseline in moderate/severe VMS frequency per day at wk 12 were −1.8, −2.1, −2.3, and −2.6 for 15, 30, 60, and 90 mg BID, respectively, and −2.1, −2.6, and −2.1 for 30, 60, and 120 mg QD, respectively, with a common SE of ~0.7 (all P<.05). Dose response was apparent in frequency and severity as early as at wk 1. The majority of TEAEs were mild or moderate in severity. There were no deaths or serious treatment-related TEAEs. This study demonstrates that fezolinetant is a safe and effective nonhormonal treatment for rapid reduction of moderate/severe menopausal VMS. (1)Fraser GL, et al. Clinical evaluation of the NK3 receptor antagonist fezolinetant (a.k.a. ESN364) for the treatment of menopausal hot flashes [abstract OR16-5]. Endocr Rev. 2017;38(3).