4. Non-Hormonal and Adjunctive Therapies
Pedagogy: This lesson uses mechanism-of-action reasoning linked to patient selection — matching the right non-hormonal drug to the right patient based on contraindications and evidence quality.
Learning Objectives
- Describe the mechanism of action of fezolinetant and elinzanetant (NK3/NK1 receptor antagonists)
- Summarise the DAYLIGHT and SKYLIGHT trial evidence for fezolinetant
- State the NICE TA1143 recommendation and its eligibility criteria
- Outline the limited role of SSRIs/SNRIs, clonidine, gabapentin, and oxybutynin
Key Facts
Neurokinin Receptor Antagonists
Fezolinetant (Veoza): oral NK3 receptor antagonist, 45mg once daily. Blocks NKB signalling at the hypothalamic thermoregulatory centre. Non-hormonal, onset from Week 1. Approved US, EU, Australia (1,2).
NICE TA1143 (2026): recommended for moderate-to-severe VMS when HRT is unsuitable. The Phase 3b DAYLIGHT trial (n=453, aged 40-65 unsuitable for HRT): significantly reduced VMS frequency (LS mean difference -1.93 vs placebo; P<0.001) and severity (-0.39; P<0.001) at week 24. Common adverse events: headache (8.8%), fatigue (5.8%). No drug-induced liver injury, though LFT monitoring advised (2).
Elinzanetant: dual NK1/NK3 antagonist. Effective in Phase 3 trials. Additional NK1 blockade may improve sleep and mood. Shown effective for endocrine therapy-associated VMS in breast cancer patients (3).
Other Non-Hormonal Options
| Agent | Evidence | Key Limitation |
|---|---|---|
| SSRIs/SNRIs | Some evidence; not first-line for VMS alone (NICE) | Paroxetine contraindicated with tamoxifen (CYP2D6) |
| Clonidine | Modest efficacy | Limited by side effects; not routinely recommended |
| Gabapentin | Effective but off-label | Drowsiness major limitation |
| Oxybutynin | Small trials show VMS reduction | Anticholinergic side effects; limited evidence |
Clinical Pearl Fezolinetant is now available for GP prescribing (NICE TA1143, 2026). It is the first evidence-based non-hormonal alternative to HRT with a novel mechanism. Know this drug — you will be asked about it by patients and colleagues.
Clinical Pearl NICE NG23 says SSRIs/SNRIs should NOT be routinely offered as first-line for VMS alone. Fezolinetant is now the preferred non-hormonal pharmacological option.
Case-Based Examples
Case 1: 55-year-old breast cancer survivor declining all hormonal treatment
Presentation: A 55-year-old with ER-positive breast cancer on letrozole has moderate VMS (8/day) and poor sleep. She declines any hormonal treatment. She has tried cooling techniques with limited benefit.
Question: What pharmacological options are available?
Model Answer: First-line: fezolinetant 45mg OD (NICE TA1143 criteria met: moderate-to-severe VMS, HRT unsuitable). Check baseline LFTs, monitor at 3 months. Onset from Week 1. If ineffective/not tolerated: consider venlafaxine 75mg (avoid paroxetine with tamoxifen/letrozole). Also offer: menopause-specific CBT (NICE-recommended for VMS and sleep). Lifestyle: regular exercise, weight management. For sleep specifically: CBT-I is evidence-based. If elinzanetant becomes available, it may have dual VMS + sleep benefit via NK1 blockade.
Case 2: GP asked to prescribe fezolinetant — eligibility and monitoring
Presentation: A 50-year-old with no contraindications to HRT but a strong preference against hormonal treatment has moderate-to-severe VMS. She has read about fezolinetant online.
Question: Does she meet NICE TA1143 criteria? What monitoring is required?
Model Answer: NICE TA1143 specifies fezolinetant for moderate-to-severe VMS when HRT is 'unsuitable.' The TA committee accepted that patient preference (after informed discussion) constitutes unsuitability. She should first receive a thorough discussion of HRT benefits and risks. If she declines after informed consent, fezolinetant can be prescribed. Monitoring: baseline LFTs before starting, repeat at 3 months, then periodically. Review VMS response at 12 weeks. The drug is available on GP prescription (not specialist-only).
Self-Assessment Questions
PLAB/MLA Mechanism of fezolinetant
Fezolinetant treats VMS by:
A. Increasing serotonin reuptake
B. Blocking NK3 receptors in the hypothalamic thermoregulatory centre
C. Activating oestrogen receptors
D. Inhibiting cyclooxygenase-2
Answer: B. Fezolinetant is a selective NK3 receptor antagonist. It blocks NKB signalling at the hypothalamic thermoregulatory centre, suppressing the overactive KNDy pathway without hormonal activity.
MRCGP SSRI to avoid with tamoxifen
Which antidepressant must be avoided in women taking tamoxifen for breast cancer?
A. Sertraline
B. Venlafaxine
C. Paroxetine
D. Escitalopram
Answer: C. Paroxetine is a potent CYP2D6 inhibitor, which reduces conversion of tamoxifen to its active metabolite endoxifen. This potentially reduces tamoxifen efficacy. NICE NG23 and IMS 2025 both flag this interaction.
Professor Evaluating the DAYLIGHT trial design
The DAYLIGHT trial specifically enrolled women 'unsuitable for hormone therapy.' Discuss the implications of this enrichment strategy for the generalisability of the findings.
A. It has no implications — all RCTs enrol selected populations
B. Enrolling HRT-unsuitable women (contraindications or strong preference) provides directly applicable evidence for the NICE TA1143 target population, but limits generalisability to the broader menopausal population where HRT remains first-line
C. DAYLIGHT proves fezolinetant is superior to HRT
D. The enrichment strategy invalidates the trial
Answer: B. DAYLIGHT's pragmatic design enrolled the population most likely to receive fezolinetant in practice — strengthening the NICE health technology assessment. However, the enrolled women may differ from the general menopausal population in baseline severity, comorbidity profile, and response expectations. Fezolinetant has not been compared head-to-head with HRT, so superiority/equivalence cannot be inferred. The SKYLIGHT trials enrolled a broader population and provide complementary evidence.
Take-Away Messages
- Fezolinetant (NK3R antagonist): first evidence-based non-hormonal treatment for VMS; NICE TA1143 approved for GP prescribing
- DAYLIGHT trial: significant VMS reduction at 24 weeks in women unsuitable for HRT
- Elinzanetant (dual NK1/NK3): effective in Phase 3 trials; may also improve sleep and mood
- SSRIs/SNRIs are NOT first-line for VMS alone; avoid paroxetine with tamoxifen
- Check baseline LFTs before fezolinetant; monitor at 3 months