Elinzanetant: Defining the Role of Dual Neurokinin-1 and Neurokinin-3 Receptor Antagonism for Management of Vasomotor Symptoms in Menopause

Abstract

Menopausal vasomotor symptoms (VMS) represent a significant public health burden, necessitating safe and effective nonhormonal treatments. The recent US Food and Drug Administration approval of elinzanetant, a first-in-class dual neurokinin-1 (NK1) and neurokinin-3 (NK3) receptor antagonist, represents a major shift and warrants a critical assessment of its role. VMS pathogenesis centers on the hypothalamic KNDy neuron network and is primarily mediated by Neurokinin B acting on the NK3 receptor. Elinzanetant’s distinctive dual mechanism, simultaneously blocking NK3 (VMS control) and NK1 (mood and sleep modulation), translates into improved patient outcomes as demonstrated across the OASIS Phase 3 program. Specifically, elinzanetant achieved a 65.2%–67.0% reduction in VMS frequency by Week 12 (OASIS 1/2) and produced clinically meaningful improvement in the PROMIS SD-SF 8b sleep disturbance score. While indirect cross-over study comparisons with fezolinetant (NK3 antagonist) suggest a numerical advantage in sleep quality for elinzanetant, head-to-head trials are required for confirmation. The drug demonstrated sustained efficacy and a favorable long-term liver safety profile, making it strategically important for the general population. Elinzanetant represents a major shift in the nonhormonal treatment approach, offering a safe and sustained alternative for managing menopausal symptoms.

INTRODUCTION

Menopausal vasomotor symptoms (VMS), include disruptive hot flashes and night sweats, which affect up to 80% of women, often lasting for 7–10 years [1]. This symptom burden compromises sleep, mood, and overall quality of life. As menopausal hormone therapy is often restricted due to contraindications or patient choice, the public health mandate calls for safe, effective, and hormone-free pharmacologic options. The targeting of the central hypothalamic mechanisms of thermoregulation has emerged as a game changer in managing VMS.

The recent FDA approval of elinzanetant (Lynkuet manufactured by Bayer), the first-in-class dual neurokinin-1 (NK1) and 3 (NK3) receptor antagonist, has revolutionised the nonhormonal treatment paradigm [2]. This commentary provides a detailed analysis of elinzanetant’s distinctive dual mechanism, the robust quantitative efficacy demonstrated across the OASIS program, its favorable long-term safety profile, and its strategic positioning against the NK3 selective antagonist, fezolinetant, and other pipeline agents.

MAIN TEXT

Pharmacodynamics and pharmacokinetics

VMS pathogenesis centers on the hypertrophy and hyperactivation of the hypothalamic KNDy neuron network following estrogen withdrawal. The key neuropeptide driving this hyperactivation is neurokinin B, acting primarily via the NK3 receptor [3].

Elinzanetant provides a crucial mechanistic refinement by simultaneously blocking both the NK3 receptor (the primary VMS target) and the NK1 receptor, the main target for substance P (SP) [3]. While NK3 antagonism effectively re-calibrates the core thermoregulatory center, the dual NK1 antagonism offers potential synergistic benefits on central nervous system pathways, including the modulation of mood, anxiety, and sleep architecture [3].

Elinzanetant is dosed as an oral 120 mg (two 60 mg capsules) orally once daily at bedtime [4]. Its pharmacokinetic profile is favorable for once-daily dosing, with a long elimination half-life of approximately 45 hours in women with VMS [4]. Due to its primary metabolism via the cytochrome P450 3A4 (CYP3A4) enzyme, careful clinical management is required, as concurrent use of strong CYP3A4 inhibitors (e.g., azole antifungals, macrolide antibiotics, protease inhibitors, etc.) is contraindicated due to the risk of increased drug exposure and toxicity [3,4]. It also requires monitoring when ministered with CYP2C9 inducers (warfarin).

Quantitative data from the OASIS program

Elinzanetant’s efficacy and safety were validated by the OASIS Phase 3 program (OASIS 1, 2, and 3), which enrolled over 1,300 postmenopausal women aged 40 to 65 years, with a mean age of approximately 54.6 years across the studies. The baseline VMS burden was significant, averaging 13.4 to 16.2 VMS episodes per day in OASIS 1 and 2, i.e., a high burden population, respectively [5,6]. The OASIS 3 represented a broader clinical population with no minimum VMS frequency requirement [7].

Primary efficacy (vasomotor symptoms reduction) at 12 weeks (OASIS 1 & 2)

The co-primary endpoints consistently demonstrated rapid and robust control at 4 and 12 weeks [5,6]:

a) VMS frequency reduction (Week 12): In OASIS 1, elinzanetant 120 mg achieved a 65.2% reduction in mean daily VMS frequency (compared to 42.2% for placebo). In OASIS 2, the reduction was 67.0% (compared to 45.9% for placebo). Statistically significant mean change from baseline for elinzanetant versus placebo in both studies (P < 0.001).

By Week 26, over 80% of participants achieved at least a 50% reduction in VMS frequency.

b) VMS severity reduction (Week 12): Elinzanetant significantly reduced mean daily VMS severity, with a statistically significant mean change from baseline versus placebo in both OASIS 1 and 2 (P < 0.001).

c) Rapid onset: Efficacy was established as early as Week 1, with a statistically significant reduction in VMS frequency from baseline, providing prompt clinical relief essential for patient adherence.

Key secondary outcome parameters (dual effect validation)

The superior improvement in secondary outcomes supports the benefit of the dual mechanism:

a) Sleep disturbance (PROMIS SD-SF 8b): At Week 12, elinzanetant demonstrated a statistically significant improvement in sleep disturbance T scores (Least squares mean difference vs. placebo: –5.6 in OASIS 1 & –4.3 in OASIS 2). The 52 week OASIS 3 trial produced T scores by –9.4 points; This moves the participants score from a moderate sleep disturbance to a normal range (< 55). OASIS 1: Δ –3.3 points vs. Δ –1.4 for placebo; OASIS 2: Δ –3.1 points vs. Δ –1.6 for placebo, P < 0.001 for both).

b) Quality of life (MENQOL): Significant and statistically superior improvements were demonstrated in menopause-related quality of life compared to placebo at Week 12. This improvement was primarily driven by the vasomotor domain with mean changes of –2.86 and –2.70 in the OASIS 1 & 2, respectively compare to the –1.50 and –1.64 for placebo. Improvement in the physical and the psychosocial domains were also observed, but were secondary to the reduction in VMS frequency and severity.

Long-term safety (OASIS 3)

Data from the OASIS 3 trial extended these findings, supporting the sustained long-term profile of elinzanetant 120 mg over 52 weeks [6,7]:

a) Common adverse events: The most frequent treatment emergent adverse events (TEAEs) were headache (9.6%), fatigue (6.7%), and somnolence (5.1%).

b) Discontinuation: The most common cause of discontinuation was headache and fatigue, and the discontinuation rates due to TEAE was 12.5%.

Consistent with the OASIS-3 safety protocols, a baseline liver profile (transaminases and total bilirubin) must be obtained prior to initiation. Elinzanetant is contraindicated in patients with:

a. Severe hepatic impairment (Child-Pugh Class C).

b. Baseline transaminases or bilirubin exceeding 2× the upper limit of normal.

While the 52-week data (OASIS-3) showed no signal of drug-induced liver injury, routine monitoring at 3 months post-initiation is suggested to maintain the favorable safety profile observed in clinical trials.

Comparative positioning and evolving pipeline

Elinzanetant enters the nonhormonal market alongside the NK3-selective antagonist fezolinetant (Veozah; Astellas) [8]. The key differentiation lies in the dual mechanism and its quantitative impact on sleep (Table 1).

Table 1. Neurokinin antagonists: indirect quantitative comparison (MD vs. placebo at Week 12).

Feature	Elinzanetant (dual NK1/NK3 antagonist)	Fezolinetant (selective NK3 antagonist)
VMS frequency reduction (MD vs. placebo, events/d)	2.99 (95% CI: 1.74–4.23)	2.54 (95% CI: 1.86–3.21)
VMS severity reduction (MD vs. placebo, score)	0.36 (95% CI: 0.26–0.46)	0.24 (95% CI: 0.13–0.34)
Sleep quality improvement (PROMIS SD-SF 8b score MD vs. placebo)	4.65 (95% CI: 3.73–5.56)	No significant improvementa

Data derived from a matching-adjusted indirect comparison of seven RCTs (n = 4,087).

MD: mean difference, NK: neurokinin, VMS: vasomotor symptoms, CI: confidence interval, RCT: randomized controlled trial.

^aSleep data for fezolinetant was inconsistently reported or failed to reach significance in the study. These are indirect cross-over study comparisons; no head-to-head trials exist.

As shown in Table 1, indirect comparisons from the OASIS (elinzanetant) and SKYLIGHT (fezolinetant) trials suggest a potential clinical differentiation in sleep and quality-of-life outcomes [9]:

The quantitatively higher impact on sleep quality suggests that NK1 antagonism may provide additional value for patients whose VMS is compounded by disruptive sleep. This is theoretically linked to the modulation of SP, which is a key neurotransmitter in central sleep and stress circuits [9]. In the absence of head-to-head randomized controlled trials, these cross-over study comparisons should be interpreted with caution. The specific contribution of the NK1 component has not been isolated from the general benefit following VMS reduction, and results may be influenced by differences in trial design and baseline symptom severity.

The comparative data support a strategy where elinzanetant is optimal for patients whose VMS is compounded by severe, disruptive sleep disturbance, given its quantitative effect on the PROMIS SD-SF 8b score [9]. This suggests that the NK1 antagonism, by modulating SP’s role in central mood and stress circuits, offers a true value-add for patients whose primary complaint is poor sleep quality.

Beyond NK antagonists, the field is exploring other neuro-modulatory approaches. This includes transient receptor potential melastatin 8 (TRPM8) channel antagonists, which offer a mechanistically distinct form of neuro-targeting by acting on peripheral sensory neurons to influence the body’s cold-sensing mechanisms and stabilize the thermoregulatory center [10]. The impressive results from cendifensine also define a potent new class of monoamine modulators (Table 2) [11].

Table 2. Evolving neuro-active pipeline: beyond neurokinin antagonism.

Drug name	Target mechanism	Stage	Rationale for VMS	Reference
MT-8554	TRPM8 antagonists	Phase 2	TRPM8 is a cold receptor; blocking it is hypothesized to dampen the body’s over-sensitivity to temperature drops, thereby stabilizing the hypothalamic thermal set point	ClinicalTrials.gov [10]
NOE-115/cendifensine	Monoamine modulator (broad-spectrum)	Phase 2a completed	Achieved a 92.3% reduction from baseline in daily frequency of moderate-to-severe VMS	Noema Pharma AG [11]

VMS: vasomotor symptoms, TRPM8: transient receptor potential melastatin.

CONCLUSION

The approval of elinzanetant, the first dual NK1/NK3 receptor antagonist, fundamentally shifts the treatment landscape for moderate-to-severe VMS. Its dual mechanism provides a quantitatively superior benefit on sleep disturbance compared to selective NK3 antagonists, making it the preferred nonhormonal option for women experiencing sleep-disruptive VMS. Furthermore, the 52-week safety profile in OASIS 3 specifically the lack of hepatotoxicity and endometrial effects reinforces its suitability for long-term use.

Clinical implementation requires a structured approach, including bedtime dosing (two 60 mg capsules) to manage the somnolence profile and careful screening for CYP3A4 interactions. While baseline liver profile testing is recommended, the current data support elinzanetant as a vital nonhormonal alternative, particularly for patients in whom hormone therapy is contraindicated. Future head-to-head clinical trials and studies in more diverse populations are warranted to further refine its position in the menopause care pathway.