Open-label, phase II, multicenter study of lasofoxifene plus abemaciclib for treating women with metastatic ER+/HER2- breast cancer and an ESR1 mutation after disease progression on prior therapies: ELAINE 2.

BACKGROUND: Acquired ESR1 mutations in estrogen receptor-positive (ER+) metastatic breast cancer (mBC) drive treatment resistance and tumor progression; new treatment strategies are needed. Lasofoxifene, a next-generation, oral, endocrine therapy and tissue-specific ER antagonist, provided preclinical antitumor activity, alone or combined with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) in ESR1-mutated mBC. PATIENTS AND METHODS: In the open-label, phase II, ELAINE 2 trial (NCT04432454), women with ESR1-mutated, ER+/human epidermal growth factor receptor 2-negative (HER2-) mBC who progressed on prior therapies (including CDK4/6i) received lasofoxifene 5 mg/day and abemaciclib 150 mg b.i.d until disease progression/toxicity. The primary endpoint was safety/tolerability. Secondary endpoints included progression-free survival (PFS), clinical benefit rate (CBR), and objective response rate (ORR). RESULTS: Twenty-nine women (median age 60 years) participated; all but one were previously treated with a CDK4/6i (median duration 2 years). The lasofoxifene-abemaciclib combination was well tolerated with primarily grade 1/2 treatment-emergent adverse events (TEAEs), most commonly diarrhea, nausea, fatigue, and vomiting. One patient (with no prior CDK4/6i) discontinued treatment due to grade 2 diarrhea. No deaths occurred during the study. Median PFS was 56.0 weeks [95% confidence interval (CI) 31.9 weeks-not estimable; ∼13 months]; PFS rates at 6, 12, and 18 months were 76.1%, 56.1%, and 38.8%, respectively. CBR at 24 weeks was 65.5% (95% CI 47.3% to 80.1%). In 18 patients with measurable lesions, ORR was 55.6% (95% CI 33.7% to 75.4%). ESR1-mutant circulating tumor DNA (ctDNA) allele fraction decreased from baseline to week 4 in 21/26 (80.8%) patients. CONCLUSIONS: Lasofoxifene plus abemaciclib had an acceptable safety profile, was well tolerated, and exhibited meaningful antitumor activity in women with ESR1-mutated, ER+/HER2- mBC after disease progression on prior CDK4/6i. Observed decreases in ESR1-mutant ctDNA with lasofoxifene concordant with clinical response suggest target engagement. If the ELAINE 2 findings are confirmed in the initiated, phase III, ELAINE 3 trial, these data could be practice-changing and help address a critical unmet need.

Lasofoxifene versus fulvestrant for ER+/HER2- metastatic breast cancer with an ESR1 mutation: results from the randomized, phase II ELAINE 1 trial.

BACKGROUND: Acquired estrogen receptor alpha (ER/ESR1) mutations commonly cause endocrine resistance in ER+ metastatic breast cancer (mBC). Lasofoxifene, a novel selective ER modulator, stabilizes an antagonist conformation of wild-type and ESR1-mutated ER-ligand binding domains, and has antitumor activity in ESR1-mutated xenografts. PATIENTS AND METHODS: In this open-label, randomized, phase II, multicenter, ELAINE 1 study (NCT03781063), we randomized women with ESR1-mutated, ER+/human epidermal growth factor receptor 2 negative (HER2-) mBC that had progressed on an aromatase inhibitor (AI) plus a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) to oral lasofoxifene 5 mg daily or IM fulvestrant 500 mg (days 1, 15, and 29, and then every 4 weeks) until disease progression/toxicity. The primary endpoint was progression-free survival (PFS); secondary endpoints were safety/tolerability. RESULTS: A total of 103 patients received lasofoxifene (n = 52) or fulvestrant (n = 51). The most current efficacy analysis showed that lasofoxifene did not significantly prolong median PFS compared with fulvestrant: 24.2 weeks (∼5.6 months) versus 16.2 weeks (∼3.7 months; P = 0.138); hazard ratio 0.699 (95% confidence interval 0.434-1.125). However, PFS and other clinical endpoints numerically favored lasofoxifene: clinical benefit rate (36.5% versus 21.6%; P = 0.117), objective response rate [13.2% (including a complete response in one lasofoxifene-treated patient) versus 2.9%; P = 0.124], and 6-month (53.4% versus 37.9%) and 12-month (30.7% versus 14.1%) PFS rates. Most common treatment-emergent adverse events with lasofoxifene were nausea, fatigue, arthralgia, and hot flushes. One death occurred in the fulvestrant arm. Circulating tumor DNA ESR1 mutant allele fraction (MAF) decreased from baseline to week 8 in 82.9% of evaluable lasofoxifene-treated versus 61.5% of fulvestrant-treated patients. CONCLUSIONS: Lasofoxifene demonstrated encouraging antitumor activity versus fulvestrant and was well tolerated in patients with ESR1-mutated, endocrine-resistant mBC following progression on AI plus CDK4/6i. Consistent with target engagement, lasofoxifene reduced ESR1 MAF, and to a greater extent than fulvestrant. Lasofoxifene may be a promising targeted treatment for patients with ESR1-mutated mBC and warrants further investigation.

Treatment of moderate to severe dyspareunia with intravaginal prasterone therapy: a review.

The loss of sex steroids (e.g. estradiol, dehydroepiandrosterone [DHEA], progesterone) that causes menopause commonly affects a woman's general health and produces bothersome physical changes that may interfere with normal sexual and genitourinary functioning. Although both over-the-counter and prescription treatments are available, there remains a large unmet need, as less than 10% of women are treated. Adrenal DHEA and its sulfate are the most abundant steroids in humans. Here we review the development of intravaginal prasterone, the synthetic equivalent to endogenous DHEA. Prasterone is approved by the US Food and Drug Administration for the treatment of moderate to severe dyspareunia, a symptom of vulvar and vaginal atrophy, due to menopause. Prasterone has been shown to decrease the pain associated with dyspareunia, and to improve vaginal pH, as well as superficial and parabasal cell counts, while maintaining serum hormone levels within the range of those seen in normal postmenopausal women. Unlike other menopausal prescription therapies, intravaginal prasterone does not carry a boxed warning, thus allowing the clinician and patient to engage in meaningful and reassuring discussion around a new approach that treats this common, debilitating condition.

Female sexual function improved with ospemifene in postmenopausal women with vulvar and vaginal atrophy: results of a randomized, placebo-controlled trial.

BACKGROUND: Ospemifene is a non-estrogen, tissue selective estrogen receptor agonist/antagonist, or selective estrogen receptor modulator, recently approved for the treatment of dyspareunia, a symptom of vulvar and vaginal atrophy (VVA), due to menopause. Postmenopausal dyspareunia is often associated with female sexual dysfunction (FSD). In this report, we present data that demonstrate the effect of ospemifene 60 mg/day on FSD assessed by the Female Sexual Function Index (FSFI), a widely used tool with six domains (Arousal, Desire, Orgasm, Lubrication, Satisfaction, and Pain). METHODS: A phase-3, randomized, double-blind, 12-week trial (n = 919) compared the efficacy and safety of oral ospemifene 60 mg/day vs. placebo in postmenopausal women with VVA in two strata based on self-reported, most bothersome symptom of either dyspareunia or dryness. Primary data were published previously. We report herein pre-specified secondary efficacy endpoints analyses, including changes from baseline to Weeks 4 and 12 for FSFI total and domain scores as well as serum hormone levels. RESULTS: Ospemifene 60 mg/day demonstrated a significantly greater FSFI total score improvement vs. placebo at Week 4 (p < 0.001). Improvement in FSFI scores continued to Week 12 (p < 0.001). At Week 4, the FSFI domains of Sexual Pain, Arousal, and Desire were significantly improved with ospemifene vs. placebo; at Week 12, improvements in all domains were significant (p < 0.05). Changes in serum hormones were minor and uncorrelated with changes in sexual functioning. CONCLUSION: In a large, randomized, double-blind, placebo-controlled trial, ospemifene 60 mg/day significantly improved FSD in women with VVA. Consistent effects across FSFI domains were observed.

Decreased efficacy of twice-weekly intravaginal dehydroepiandrosterone on vulvovaginal atrophy.

OBJECTIVE: While daily intravaginal administration of 0.50% (6.5 mg) dehydroepiandrosterone (DHEA, prasterone) for 12 weeks has shown clinically and statistically significant effects on moderate to severe (MS) dyspareunia as the most bothersome symptom (MBS), the present study analyzes the effect of a reduced dosing regimen on MBS vaginal dryness. METHOD: Daily intravaginal 0.50% prasterone for 2 weeks followed by twice weekly for 10 weeks versus placebo. RESULTS: Maximal beneficial changes in vaginal parabasal and superficial cells and pH were observed at 2 weeks as observed for intravaginal 10 µg estradiol (E2). This was followed by a decrease or lack of efficacy improvement after switching to twice-weekly dosing. The decrease in percentage of parabasal cells, increase in percentage of superficial cells and decrease in vaginal pH were all highly significant (p < 0.0001 to 0.0002 over placebo) at 12 weeks. In parallel, the statistical significance over placebo (p value) on MBS vaginal dryness at 6 weeks was 0.09 followed by an increase to 0.198 at 12 weeks. For MBS dyspareunia, the p value of 0.008 at 6 weeks was followed by a p value of 0.077 at 12 weeks, thus illustrating a decrease of efficacy at the lower dosing regimen. The improvements of vaginal secretions, color, epithelial integrity and epithelial surface thickness were observed at a p value < 0.01 or 0.05 over placebo at 2 weeks, with a similar or loss of statistical difference compared to placebo at later time intervals. No significant adverse event was observed. Vaginal discharge related to the melting of Witepsol was reported in 1.8% of subjects. CONCLUSION: The present data show that daily dosing with 0.50% DHEA for 2 weeks followed by twice-weekly dosing is a suboptimal treatment of the symptoms/signs of vulvovaginal atrophy resulting from a substantial loss of the efficacy achieved at daily dosing.

Genitourinary syndrome of menopause: new terminology for vulvovaginal atrophy from the International Society for the Study of Women's Sexual Health and the North American Menopause Society.

BACKGROUND: In 2012, the Board of Directors of the International Society for the Study of Women's Sexual Health (ISSWSH) and the Board of Trustees of The North American Menopause Society (NAMS) acknowledged the need to review current terminology associated with genitourinary tract symptoms related to menopause. METHODS: The 2 societies cosponsored a terminology consensus conference, which was held in May 2013. RESULTS AND CONCLUSION: Members of the consensus conference agreed that the term genitourinary syndrome of menopause (GSM) is a medically more accurate, all-encompassing, and publicly acceptable term than vulvovaginal atrophy. GSM is defined as a collection of symptoms and signs associated with a decrease in estrogen and other sex steroids involving changes to the labia majora/minora, clitoris, vestibule/introitus, vagina, urethra and bladder. The syndrome may include but is not limited to genital symptoms of dryness, burning, and irritation; sexual symptoms of lack of lubrication, discomfort or pain, and impaired function; and urinary symptoms of urgency, dysuria and recurrent urinary tract infections. Women may present with some or all of the signs and symptoms, which must be bothersome and should not be better accounted for by another diagnosis. The term was presented and discussed at the annual meeting of each society. The respective Boards of NAMS and ISSWSH formally endorsed the new terminology--genitourinary syndrome of menopause (GSM)--in 2014.

Genitourinary syndrome of menopause: new terminology for vulvovaginal atrophy from the International Society for the Study of Women's Sexual Health and The North American Menopause Society.

BACKGROUND: In 2012, the Board of Directors of the International Society for the Study of Women's Sexual Health (ISSWSH) and the Board of Trustees of The North American Menopause Society (NAMS) acknowledged the need to review current terminology associated with genitourinary tract symptoms related to menopause. METHODS: The two societies cosponsored a terminology consensus conference, which was held in May 2013. RESULTS AND CONCLUSION: Members of the consensus conference agreed that the term genitourinary syndrome of menopause (GSM) is a medically more accurate, all-encompassing, and publicly acceptable term than vulvovaginal atrophy. GSM is defined as a collection of symptoms and signs associated with a decrease in estrogen and other sex steroids involving changes to the labia majora/minora, clitoris, vestibule/introitus, vagina, urethra and bladder. The syndrome may include but is not limited to genital symptoms of dryness, burning, and irritation; sexual symptoms of lack of lubrication, discomfort or pain, and impaired function; and urinary symptoms of urgency, dysuria and recurrent urinary tract infections. Women may present with some or all of the signs and symptoms, which must be bothersome and should not be better accounted for by another diagnosis. The term was presented and discussed at the annual meeting of each society. The respective Boards of NAMS and ISSWSH formally endorsed the new terminology - genitourinary syndrome of menopause (GSM) - in 2014.

Ospemifene 12-month safety and efficacy in postmenopausal women with vulvar and vaginal atrophy.

OBJECTIVE: Assessment of 12-month safety of ospemifene 60 mg/day for treatment of postmenopausal women with vulvar and vaginal atrophy (VVA). METHODS: In this 52-week, randomized, double-blind, placebo-controlled, parallel-group study, women 40-80 years with VVA and an intact uterus were randomized 6 : 1 to ospemifene 60 mg/day or placebo. The primary objective was 12-month safety, particularly endometrial; 12-week efficacy was assessed. Safety assessments included endometrial histology and thickness, and breast and gynecological examinations. Efficacy evaluations included changes from baseline to week 12 in percentage of superficial and parabasal cells and vaginal pH. RESULTS: Of 426 randomized subjects, 81.9% (n = 349) completed the study with adverse events the most common reason for discontinuation (ospemifene 9.5%; placebo 3.9%). Most (88%) treatment-emergent adverse events with ospemifene were considered mild or moderate. Three cases (1.0%) of active proliferation were observed in the ospemifene group. For one, active proliferation was seen at end of study week 52, and diagnosed as simple hyperplasia without atypia on follow-up biopsy 3 months after the last dose. This subsequently resolved with progestogen treatment and dilatation and curettage. In six subjects (five ospemifene (1.4%), one placebo (1.6%)) endometrial polyps were found (histopathology); however, only one (ospemifene) was confirmed as a true polyp during additional expert review. Endometrial histology showed no evidence of carcinoma. Statistically significant improvements were seen for all primary and secondary efficacy measures and were sustained through week 52 with ospemifene vs. placebo. CONCLUSIONS: The findings of this 52-week study confirm the tolerance and efficacy of oral ospemifene previously reported in short- and long-term studies.