Key Takeaways:
- Of elinzanetant's (Lynkuet) total sleep treatment effect (−4.92), 54.3% was attributable to a direct effect independent of nighttime VMS reduction, implicating NK1 receptor blockade as a novel sleep-specific mechanism.
- The direct sleep benefit was observed even in OASIS-3, which had no minimum hot flash enrollment requirement, suggesting the effect is not dependent on baseline VMS severity.
- Because hot flashes account for only approximately one third of nocturnal wakefulness in menopausal women, elinzanetant's direct sleep pathway may address the majority of sleep disruption that VMS-targeted treatment alone cannot reach.
A mediation analysis of pooled data from 4 elinzanetant (Lynkuet) clinical trials found that more than half of the drug's sleep benefit occurs independently of nighttime vasomotor symptom reduction—a finding that reframes both the mechanism of elinzanetant and the nature of menopausal sleep disruption itself, according to Pauline M. Maki, PhD.1
The analysis, presented at the SLEEP 2026 Annual Meeting, drew on pooled data from the phase 3 OASIS-1, -2, and -3 trials and the phase 2 NIRVANA trial, comprising 1345 postmenopausal women. Using longitudinal causal mediation analysis, investigators partitioned elinzanetant's total treatment effect on sleep into a natural direct effect—improvement independent of nighttime VMS reduction—and a natural indirect effect mediated by VMS reduction. The total treatment effect on PROMIS Sleep Disturbance scores was −4.92 (95% CI, −5.73 to −4.12). Of that, 54.3% was attributable to the direct effect (NDE: −2.67; 95% CI, −3.28 to −2.07), with the remainder mediated through nighttime VMS reduction (NIE: −2.25; 95% CI, −2.81 to −1.69).
"About half of the treatment benefit of elinzanetant on sleep—which is a reliable benefit seen in every randomized trial to date—is actually direct," Maki said. She described the NK1 receptor as a potentially novel mechanism underlying sleep disturbance in midlife women, distinct from the vasomotor pathway targeted by NK3 blockade.
The finding held across trial populations with meaningfully different enrollment criteria. OASIS-3 had no minimum hot flash requirement for enrollment—a design that generalizes more broadly to the clinical range of menopausal symptom burden than trials requiring 35 or 50 or more hot flashes per week.
"The fact that women didn't have to meet a minimum threshold for the number of hot flashes does suggest that maybe it's not the magnitude of the hot flash burden that determines the benefits of elinzanetant on sleep," Maki said. "Maybe it's a general benefit that may not be dependent on the severity of those symptoms."
That interpretation aligns with a broader point Maki returned to across her research: Hot flashes account for only about one third of the total time menopausal women spend awake at night. The remaining two thirds reflects other menopause-associated changes to sleep architecture that occur independently of vasomotor events.
"Two thirds of the time that they're awake is really associated with just some phenomenon associated with menopause," she said. Elinzanetant's direct sleep benefit may be acting on precisely that component—the sleep disruption that VMS-targeted treatment alone cannot reach.
REFERENCE
1. Maki P, Trigg A, Joffe H, et al. Elinzanetant improves sleep disturbances party independent of nighttime vasomotor symptoms: Post-hoc mediation analysis from four trials. Sleep. 2026;49(Suppl 1):A375-A376
