Effect of Estetrol Monohydrate (E4) on QTc Interval

This is a Phase 1, multicenter, randomized, placebo- and active-controlled, partially double-blinded, single-dose, 4-way crossover study in healthy postmenopausal female participants to evaluate the effect of E4 on the QTc interval. All participants will receive all 4 study treatments (E4 therapeutic dose \[20 mg\]; E4 supratherapeutic dose \[100 mg\]; placebo; moxifloxacin \[400 mg\]) in a randomized sequence.

E4 and placebo administration will be blinded while moxifloxacin will be provided in an open-label fashion.

Participants will report to the clinical research unit (CRU) for the eligibility screening within 28 days prior to the first study drug administration. Participants will sign the study specific informed consent form (ICF) prior to any study specific screening procedures being performed.

In each study period, the participants will be confined in the CRU from the day before dosing (Day -1) until all safety assessments have been completed on Day 2, for a total of 2 days per period. Each study period will be separated by a 14 day (±2 days) washout.

Cardiodynamic assessment using continuous 12-lead ECG (Holters) recordings will be performed on Day 1 of each treatment period starting approximately 1 hour before dosing and ending approximately 25 hours after dosing. ECGs will be extracted serially pre- and postdose and at predefined time points. Blood draws for PK will be performed in all periods after each ECG extraction.

All participants (including participants who terminate the study prematurely) will receive a follow-up call 7 (±2) days after the last administration of study treatment to determine if any adverse events (AEs) have occurred since the last study visit.