Oral lasofoxifene's effects on moderate to severe vaginal atrophy in postmenopausal women: two phase 3, randomized, controlled trials

Abstract Objective The aim of this study was to demonstrate whether lasofoxifene improves vaginal signs/symptoms of genitourinary syndrome of menopause. Methods Two identical, phase 3 trials randomized postmenopausal women with moderate to severe vaginal symptoms to oral lasofoxifene 0.25 or 0.5 mg/d, or placebo, for 12 week. Changes from baseline to week 12 in most bothersome symptom, vaginal pH, and percentages of vaginal parabasal and superficial cells were evaluated. These coprimary endpoints were analyzed using analysis of covariance, except superficial cells, which were analyzed by the nonparametric, rank-based Kruskal-Wallis test. Results The two studies enrolled 444 and 445 women (mean age, ~60 y), respectively. Coprimary endpoints at week 12 improved with lasofoxifene 0.25 and 0.5 mg/d greater than with placebo (P < 0.0125 for all). Study 1: most bothersome symptom (least square mean difference from placebo: −0.4 and −0.5 for 0.25 and 0.5 mg/d, respectively), vaginal pH (−0.65, −0.58), and vaginal superficial (5.2%, 5.4%), and parabasal (−39.9%, −34.9%) cells; study 2: most bothersome symptom (−0.4, −0.5), vaginal pH (−0.57, −0.67), and vaginal superficial (3.5%, 2.2%) and parabasal (−34.1%, −33.5%) cells. Some improvements occurred as early as week 2. Most treatment-emergent adverse events were mild or moderate and hot flushes were most frequently reported (lasofoxifene vs placebo: 13%–23% vs 9%–11%). Serious adverse events were infrequent and no deaths occurred. Conclusions In two phase 3 trials, oral lasofoxifene 0.25 and 0.5 mg/d provided significant and clinically meaningful improvements in vaginal signs/symptoms with a favorable safety profile, suggesting beneficial effects of lasofoxifene on genitourinary syndrome of menopause.