Pharmacotherapeutic group: Other gynaecologicals, other gynaecologicals, ATC code: G02CX06.
Mechanism of action
Fezolinetant is a non-hormonal selective neurokinin 3 (NK3) receptor antagonist. It blocks neurokinin B (NKB) binding on the kisspeptin/neurokinin B/dynorphin (KNDy) neuron, which is postulated to restore the balance in KNDy neuronal activity in the thermoregulatory centre of the hypothalamus.
Pharmacodynamic effects
In postmenopausal women, with fezolinetant treatment, a transient decrease of luteinizing hormone (LH) levels was observed. No clear trends or clinically relevant changes in sex hormones measured (follicle-stimulating hormone (FSH), testosterone, oestrogen, and dehydroepiandrosterone sulphate) in postmenopausal women were observed.
Clinical efficacy and safety
Efficacy: Effects on VMS
The effects of fezolinetant were studied in postmenopausal women with moderate to severe VMS in two 12-week, randomised, placebo-controlled, double-blind phase 3 studies of identical design, followed by a 40-week extension treatment period (SKYLIGHT 1 – 2693-CL-0301 and SKYLIGHT 2 – 2693-CL-0302). Women who had a minimum average of 7 moderate to severe VMS per day were enrolled in the studies.
The study population included postmenopausal women defined as having amenorrhoea for ≥ 12 consecutive months (70.1%) or amenorrhoea for ≥ 6 months with FSH > 40 IU/l (4.1%) or having had bilateral oophorectomy ≥ 6 weeks prior to the screening visit (16.1%).
The study population included postmenopausal women with one or more of the following: prior hormone replacement therapy (HRT) use (19.9%), prior oophorectomy (21.6%), or prior hysterectomy (32.1%).
In the studies, a total of 1022 postmenopausal women (81% Caucasian, 17% Black, 1% Asian, 24% Hispanic/Latina ethnicity, and aged ≥ 40 years and ≤ 65 years with an average age of 54 years) were randomised and stratified by smoking status (17% smokers).
The 4 co-primary efficacy endpoints for both studies were the change from baseline in moderate to severe VMS frequency and severity to weeks 4 and 12 as defined in the Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines. Each study demonstrated a statistically significant and clinically meaningful (≥ 2 hot flashes per 24 hours) reduction from baseline in the frequency of moderate to severe VMS to weeks 4 and 12 for fezolinetant 45 mg compared to placebo. Data from the studies showed a statistically significant reduction from baseline in the severity of moderate to severe VMS to weeks 4 and 12 for fezolinetant 45 mg compared to placebo.
Results of the co-primary endpoint for change from baseline to weeks 4 and 12 in mean frequency of moderate to severe VMS per 24 hours from SKYLIGHT 1 and 2 and from pooled studies are shown in Table 2.
Table 2. Mean baseline and change from baseline to weeks 4 and 12 for mean frequency of moderate to severe VMS per 24 hours
| Parameter | SKYLIGHT 1 | SKYLIGHT 2 | Pooled studies (SKYLIGHT 1 and 2) |
| Fezolinetant 45 mg (n=174) | Placebo (n=175) | Fezolinetant 45 mg (n=167) | Placebo (n=167) | Fezolinetant 45 mg (n=341) | Placebo (n=342) |
| Baseline |
| Mean (SD) | 10.44 (3.92) | 10.51 (3.79) | 11.79 (8.26) | 11.59 (5.02) | 11.10 (6.45) | 11.04 (4.46) |
| Change from baseline to week 4 |
| LS Mean (SE) Mean % Reduction2 Difference vs Placebo (SE) P-value | -5.39 (0.30) 50.63% -2.07 (0.42) < 0.0011 | -3.32 (0.29) 30.46% -- -- | -6.26 (0.33) 55.16% -2.55 (0.46) < 0.0011 | -3.72 (0.33) 33.60% -- -- | -5.79 (0.23) 52.84% -2.28 (0.32) < 0.001 | -3.51 (0.22) 31.96% -- -- |
| Change from baseline to week 12 |
| LS Mean (SE) Mean % Reduction2 Difference vs Placebo (SE) P-value | -6.44 (0.31) 61.35% -2.55 (0.43) < 0.0011 | -3.90 (0.31) 34.97% -- -- | -7.50 (0.39) 64.27% -2.53 (0.55) < 0.0011 | -4.97 (0.39) 45.35% -- -- | -6.94 (0.25) 62.80% -2.51 (0.35) < 0.001 | -4.43 (0.25) 40.18% -- -- |
1 Statistically significantly superior compared to placebo at the 0.05 level with multiplicity adjustment.
LS Mean: Least Squares Mean estimated from a mixed model for repeated measures analysis of covariance;
SD: Standard Deviation; SE: Standard Error.
2 Mean % Reduction is a descriptive statistic and not from the mixed model.
Results of the co-primary endpoint for change from baseline to weeks 4 and 12 in mean severity of moderate to severe VMS per 24 hours from SKYLIGHT 1 and 2 and from pooled studies are shown in Table 3.
Table 3. Mean baseline and change from baseline to weeks 4 and 12 for mean severity of moderate to severe VMS per 24 hours
| Parameter | SKYLIGHT 1 | SKYLIGHT 2 | Pooled studies (SKYLIGHT 1 and 2) |
| Fezolinetant 45 mg (n=174) | Placebo (n=175) | Fezolinetant 45 mg (n=167) | Placebo (n=167) | Fezolinetant 45 mg (n=341) | Placebo (n=342) |
| Baseline |
| Mean (SD) | 2.40 (0.35) | 2.43 (0.35) | 2.41 (0.34) | 2.41 (0.32) | 2.40 (0.35) | 2.42 (0.34) |
| Change from baseline to week 4 |
| LS Mean (SE) Difference vs Placebo (SE) P-value | -0.46 (0.04) -0.19 (0.06) 0.0021 | -0.27 (0.04) -- -- | -0.61 (0.05) -0.29 (0.06) < 0.0011 | -0.32 (0.05) -- -- | -0.53 (0.03) -0.24 (0.04) < 0.001 | -0.30 (0.03) -- -- |
| Change from baseline to week 12 |
| LS Mean (SE) Difference vs Placebo (SE) P-value | -0.57 (0.05) -0.20 (0.08) 0.0071 | -0.37 (0.05) -- -- | -0.77 (0.06) -0.29 (0.08) < 0.0011 | -0.48 (0.06) -- -- | -0.67 (0.04) -0.24 (0.06) < 0.001 | -0.42 (0.04) -- -- |
1 Statistically significantly superior compared to placebo at the 0.05 level with multiplicity adjustment.
LS Mean: Least Squares Mean estimated from a mixed model for repeated measures analysis of covariance;
SD: Standard Deviation; SE: Standard Error.
Safety: Endometrial safety
In the long-term safety data (SKYLIGHT 1, 2, and 4), endometrial safety of fezolinetant 45 mg was assessed by transvaginal ultrasound and endometrial biopsies (304 women had baseline and post‑baseline endometrial biopsies during 52 weeks of treatment).
Endometrial biopsy assessments did not identify an increased risk of endometrial hyperplasia or malignancy according to pre-specified criteria for endometrial safety. Transvaginal ultrasound did not reveal increased endometrial thickness.
Paediatric population
The European Medicines Agency has waived the obligation to submit the results of studies with fezolinetant in all subsets of the paediatric population for the treatment of moderate to severe VMS associated with menopause (see section 4.2 for information on paediatric use).