Abstract
Introduction: Vasomotor symptoms (VMS), caused by declining estrogen in menopausal women, are common and debilitating. Hormone therapy is effective in many women but carries risks and may be contraindicated. Biological and clinical evidence shows a modulatory role for neurokinin (NK) receptor antagonists acting primarily via hypothalamic KNDy (kisspeptin, NK, dynorphin) neurons on VMS. NT-814 is an oral non-hormonal dual NK1,3 receptor antagonist which has previously been shown to cause rapid and marked improvements in VMS in post-menopausal women. This Phase-2b trial (SWITCH-1) was undertaken to further evaluate efficacy and safety and to establish the optimum dose(s) for Phase 3 studies.
Methods: SWITCH-1 was a double-blind, placebo-controlled, adaptive-randomization, dose-finding trial in 199 post-menopausal women. After a 2-week single-blind placebo run-in to establish symptom stability, women (40 to 65 years) with ≥7 moderate and/or severe VMS per day at baseline were randomized to 12 weeks of once daily treatment with placebo or one of 4 doses of NT-814: 40 mg, 80 mg, 120 mg, 160 mg. Subjects recorded the frequency and severity of VMS in electronic diaries twice daily throughout the study. Patient-reported measures of quality-of-life, sleep and mood were collected periodically. Adverse events (AEs) were recorded at each clinic visit.
Results: VMS frequency was reduced in all treatment groups, including placebo. VMS reductions were significantly greater with the 2 higher NT-814 doses at most time-points, as early as the first week of treatment. Least squares mean reductions from baseline in moderate/severe VMS per day at week 4 were: placebo, 2.7; 40 mg, 4.3 (p=0.161 vs placebo); 80 mg, 4.1 (p=0.326); 120 mg, 6.7 (p<0.0001); 160 mg, 5.5 (p=0.007). In week 12 the reductions were: placebo, 4.7; 40 mg, 6.5 (p=0.185); 80 mg, 5.6 (p=0.599); 120 mg, 7.8 (p=0.009); 160 mg, 6.6 (p=0.109). At the 160 mg dose the median reduction in week 12 was significantly greater than placebo (6.9 vs 4.4, p=0.0023), indicating an effect of high outliers on the mean. Average HF severity was also improved in a dose-related manner, with greater reductions compared to placebo with the 2 higher NT-814 doses. Improvements in HF were accompanied by statistically significant benefits on sleep (assessed using the Insomnia Severity Index and Pittsburgh Sleep Quality Index), mood (measured using the Beck Depression Inventory), and all four domains of the MenQoL menopause-specific quality-of-life instrument. NT-814 was well-tolerated; most AEs were mild or moderate and there were no serious AEs related to treatment.
Conclusions: NT-814, a once daily non-hormonal NK antagonist, at doses of 120 & 160 mg reduced the frequency and severity of VMS and significantly improved quality of life, mood and sleep, in postmenopausal women. NT-814 was well tolerated, with a safety profile that supports further evaluation in Phase 3 trials.
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