New Data Shows Year-Long Relief from Hot Flashes and Improved Sleep, But Some Answers Still Pending
What Happened
A major Phase 3 randomized clinical trial (OASIS-3), published September 8, 2025 in JAMA Internal Medicine, has provided extended data on elinzanetant for treating moderate to severe vasomotor symptoms (VMS), i.e. hot flashes, in postmenopausal women.
In the trial, over 600 women (aged ~40-65) were randomized to once-daily oral 120 mg elinzanetant or placebo for 52 weeks. The primary outcome: change in frequency of moderate to severe hot flashes at 12 weeks. Secondary/exploratory outcomes included hot flash severity, sleep disturbance, and quality of life over 50-52 weeks.
Key findings:
- At week 12, women taking elinzanetant saw a significantly greater reduction in daily moderate to severe VMS frequency vs placebo (mean reduction ~5.4 vs ~3.5 per day).
- These improvements in hot flash frequency and severity were sustained out to week 50.
- There were also improvements in sleep disturbance scores and menopause-related quality of life, though the trial was not powered to prove statistical significance on those secondary endpoints.
Safety findings: no evidence of hepatotoxicity (liver damage) or endometrial hyperplasia; bone density and markers were stable; there were more treatment-related adverse events than placebo (e.g. somnolence, fatigue, headache).
Why It Matters
This 52-week trial strengthens evidence for elinzanetant by providing longer-term data. Earlier trials (OASIS-1 and OASIS-2) were shorter in duration; OASIS-3 shows sustained benefit over a full year. That’s important because menopausal symptoms (especially hot flashes and sleep disturbance) often last many years.
More robust safety data over a year helps clinicians and women better weigh risks vs benefits—particularly for non-hormonal options. Also, the lack of requirement for a minimum number of hot flashes per week in some enrollment criteria makes the results more relevant to a broader group of women, not just those with extremely frequent symptoms.
What This Means for Women in Perimenopause & Menopause
If you read our earlier article, Elinzanetant Under FDA Review as a Potential New Option for Menopausal Symptoms, this new trial gives you more detail on how it might perform over the long haul.
For women experiencing hot flashes:
- You may see relief in symptom frequency and severity within 12 weeks.
- Improvements in sleep may follow, though the evidence is “descriptive” for now.
- Even beyond that, benefits appear to sustain over nearly a full year.
For women who can’t or prefer not to use hormones, elinzanetant is looking increasingly promising as a non-hormonal option.
Access & Availability
- The drug remains under FDA review; this trial adds strong evidence but is not yet an approval guarantee.
- Many of the trial sites were in North America and Europe, so it’s relevant to Western markets, though regulatory timing will vary.
Benefits & Risks
Benefits
- Significant and sustained reduction of hot flashes (moderate to severe).
- Potential improvements in sleep and quality of life.
- Non-hormonal mechanism—important for women with contraindications to hormone therapy.
Risks and Other Considerations
- Higher rate of treatment-related adverse events compared to placebo (somnolence, fatigue, headache).
- Some lab value changes (liver enzymes in few women) but no strong signal of serious liver injury in this trial.
- Not yet enough data for women with certain preexisting conditions (e.g. recent cancer) or for representation across all ethnic groups.
Next Steps / What to Watch For
- FDA’s decision and labeling, once approved, will need to include long-term safety guidance.
- Watch for post-approval studies and real-world evidence to confirm the trial findings.
- Side effect monitoring, especially for sleep disruptions, fatigue, or neurological symptoms.
- Data from subgroups (older postmenopausal women, those with comorbidities) to see how broadly applicable benefits are.
What This Means for Your Midlife Health
This latest trial gives stronger reasons for optimism. The growing data suggest elinzanetant is not just a hopeful experimental option but one that may become a practical, long-term tool in menopause symptom management—especially for hot flashes and sleep disruption. As regulatory decisions occur, you’ll be among those who have detailed, up-to-date info for conversations with your healthcare provider.
Further Reading
If you’re curious to dive deeper, check out these resources: