Fezolinetant treatment of moderate-to-severe vasomotor symptoms due to menopause: effect of intrinsic and extrinsic factors in two phase 3 studies (SKYLIGHT 1 and 2)

A profile of safety and efficacy of fezolinetant for the treatment of menopausal vasomotor symptoms

INTRODUCTION

Fezolinetant is a first-in-class non-hormonal pharmacological treatment recently approved for moderate-to-severe vasomotor symptoms (VMS) associated with menopause. Its mechanism of action selectively targets the pathophysiology of VMS at hypothalamic level, antagonizing binding of neurokinin B, overexpressed in estrogen deprived menopausal women, to the neurokinin 3 receptor (NK3R) in the thermoregulatory center.

AREAS COVERED

Fezolinetant reduced VMS frequency and severity in phase 3 randomized placebo-controlled trials in healthy menopausal women (SKYLIGHT 1 and 2) and in women unsuitable for menopause hormone therapy (MHT) (DAYLIGHT). The effect on VMS positively translated into improvements in menopause-specific quality of life, as well as sleep disturbances and impairment. Safety data were reassuring across studies, especially 52-weeks safety trials (SKYLIGHT 4 and MOONLIGHT 3).

EXPERT OPINION

Fezolinetant represents a highly anticipated innovation, offering the possibility to bridge the therapeutic gap for many women who cannot or do not wish to use MHT. While the potential application of fezolinetant in some clinical settings will add substantial value to the management of VMS, some research gaps need to be addressed in order to provide meaningful insight into the benefit-risk profile that ultimately will improve counseling and prescription tailoring in symptomatic menopausal women.

In Vitro Evaluation of CYP-Mediated Metabolism of Fezolinetant and Pharmacokinetic Interaction Between Fezolinetant and Fluvoxamine in Healthy Postmenopausal Smokers and Nonsmokers

Fezolinetant is an oral, nonhormonal, neurokinin 3 receptor antagonist treatment option for moderate to severe vasomotor symptoms associated with menopause. An in vitro study using human recombinant cytochrome P450 (CYP) enzymes and human liver microsomes showed that fezolinetant is metabolized to its major but inactive metabolite, ES259564, predominantly through CYP1A2, with minor contributions from CYP2C9 and CYP2C19. The clinical impact of CYP1A2 inhibition and induction on single-dose pharmacokinetics of fezolinetant was assessed in an open-label, single-sequence, phase 1 study in healthy postmenopausal women, where the impact of fluvoxamine, a strong CYP1A2 inhibitor, and smoking, a moderate CYP1A2 inducer, were evaluated. In total, 18 participants, 9 of whom were smokers, were enrolled. Fezolinetant pharmacokinetics were evaluated after a single 30-mg dose on Day 1 and Day 7. Fluvoxamine 50 mg was administered as a single dose on Days 3 and 10 and twice daily from Days 4 to 9. Fluvoxamine increased geometric mean ratio of fezolinetant maximum plasma concentrations (Cmax) and area under the curve from time of dosing extrapolated to infinity (AUCinf) to 182% and 939%, respectively, while ES259564 Cmax decreased to 20.1% with no significant change in AUC. In smokers versus nonsmokers, when fezolinetant was administered alone, fezolinetant Cmax and AUCinf decreased to 71.7% and 48.3%, respectively, while ES259564 Cmax increased to 130.2% and AUCinf decreased to 81.8%. A single oral 30-mg dose of fezolinetant was considered safe and well tolerated when co-administered with fluvoxamine in healthy postmenopausal women.

Management of vasomotor symptoms in cancer patients

Many cancer treatments can lead to reduced levels of sex hormones, which in turn may cause vasomotor symptoms (VMS) such as hot flashes. These symptoms are associated with impaired quality of life, as well as suboptimal tolerability of and adherence to cancer treatment. Hormone therapy, performed by increasing estradiol or testosterone levels, is the gold standard for treatment of VMS. However, this approach is generally contraindicated in patients with hormone-sensitive cancers. Nonhormone agents with low to moderate efficacy in controlling VMS are available, but their use may be limited by side effects and tolerability. In this narrative review, the approach to VMS in cancer patients will be discussed. The evidence for various treatment options, including novel agents such as fezolinetant that target the hypothalamic thermoregulatory pathway, will be evaluated. Finally, special considerations in different patient populations based on cancer types (eg, breast, prostate) and age groups (eg, older adults) will be explored.

Pharmacokinetic evaluation of fezolinetant for the treatment of vasomotor symptoms caused by menopause

INTRODUCTION

Vasomotor symptoms (VMS) affect the majority of menopausal women, with possible negative impact on several domains of quality of life (QoL). Although menopausal hormone therapy (MHT) represents an effective treatment, the risk-benefit profile is not favorable for every woman. Non-hormonal options are limited in number and efficacy.

AREAS COVERED

Fezolinetant is a novel oral non-hormonal drug recently approved for the treatment of moderate-severe VMS. It acts as an antagonist of neurokinin 3 receptor (NK3R), the main target of neurokinin B (a tachykinin over-expressed by kisspeptin/neurokinin B/dynorphin [KNDy] neurons after menopausal hypoestrogenism), involved in the modulation of the thermoregulatory hypothalamic center. Here, we report pharmacodynamics and pharmacokinetic properties of fezolinetant as well as its efficacy and safety data from available clinical trials.

EXPERT OPINION

Fezolinetant has shown efficacy in reducing the frequency and severity of VMS with a positive impact on sleep- and health-related QoL and acceptable safety and tolerability profile. Given the limited availability of effective non-hormonal options for VMS, fezolinetant could potentially represent a game-changer for care of menopausal women, especially when relative or absolute contraindications to MHT use are present. Further studies to gain more information about the safety profile and potential extra-VMS benefits or disadvantages are warranted in real-life clinical practice.

Treating moderate-to-severe menopausal vasomotor symptoms with fezolinetant: analysis of responders using pooled data from two phase 3 studies (SKYLIGHT 1 and 2)

OBJECTIVES

The aims of the study were to further characterize the efficacy of fezolinetant for the treatment of moderate-to-severe vasomotor symptoms (VMS) due to menopause using responder analysis and to investigate whether efficacy, not adjusted for placebo, resulted in clinically meaningful within-patient change.

METHODS

This prespecified analysis used pooled data from two phase 3, randomized, double-blind, placebo-controlled studies (SKYLIGHT 1 and 2). Responders were those experiencing ≥50%, ≥75%, ≥90%, or 100% reduction in VMS frequency from baseline to weeks 4 and 12. Responder analysis was performed for patient-reported outcome (PRO) measures to evaluate participants achieving a clinically meaningful within-patient change (not placebo adjusted) at week 4 and 12 versus baseline. Single responders were based on outcomes of VMS frequency, Patient-Reported Outcomes Measurement Information System Sleep Disturbance-Short Form 8b Total Score, Menopause-Specific Quality of Life (MENQoL) Total Score, and MENQoL VMS Domain Score. Double and triple responder analyses combined VMS frequency plus one or more of the PRO. Patient Global Impression of Change VMS was deemed a suitable anchor measure for meaningful within-patient change in VMS frequency.

RESULTS

A greater proportion of fezolinetant-treated versus placebo-treated participants had ≥50%, ≥75%, ≥90%, or 100% reduction in VMS frequency from baseline to weeks 4 and 12. A greater proportion of responders were observed in the fezolinetant groups versus placebo at week 12 in all four single responder analyses. In the double and triple responder analyses, odds ratios were supportive of a beneficial effect for both doses of fezolinetant versus placebo.

CONCLUSIONS

Fezolinetant was associated with significantly higher within-patient clinically meaningful improvement in important PRO, including VMS frequency, PROMIS SD SF 8b Total Score, MENQoL Total Score, and MENQoL VMS Domain Score.

Fezolinetant: a novel nonhormonal therapy for vasomotor symptoms due to menopause

INTRODUCTION

During menopause, the majority of women experience vasomotor symptoms which may lead to several untoward effects and negatively impact quality of life. Fezolinetant, a novel agent directly targeting the underlying pathophysiology of menopause-associated vasomotor symptoms, offers an alternative to hormonal therapies for which many patients have a contraindication or unwillingness to take due to safety concerns.

AREAS COVERED

This review summarizes key pharmacologic, pharmacokinetic, and pharmacodynamic parameters of fezolinetant along with efficacy and safety data derived from clinical trials. A literature search of peer-reviewed publications evaluating the efficacy and safety of fezolinetant was conducted using PubMed and EMBASE databases. A review of registered trials in clinicaltrials.gov was evaluated to identify ongoing studies.

EXPERT OPINION

Placebo-controlled studies demonstrated that fezolinetant led to a statistically significant reduction in vasomotor symptom frequency and severity among patients with moderate-to-severe vasomotor symptoms. The most common adverse event is headache (5-10%) and no serious safety signals have been noted. Direct head-to-head comparison with hormonal therapies and nonhormonal therapies for vasomotor symptoms, assessment of sleep outcomes, and evaluation of efficacy and safety beyond 1 year are key areas where additional data are still needed.