1. Assessment of the safe and efficacious dose of the selective progesterone receptor modulator vilaprisan for the treatment of patients with uterine fibroids by exposure–response modelling and simulation
- Author
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Christian Seitz, Kathrin Petersdorf, Bart Ploeger, Matthias Frei, Marcus-Hillert Schultze-Mosgau, and Gabriele Sutter
- Subjects
Pharmacology ,medicine.medical_specialty ,education.field_of_study ,Estradiol ,Leiomyoma ,Uterine fibroids ,business.industry ,Population ,Urology ,medicine.disease ,Pharmacokinetics ,Oral administration ,Pharmacodynamics ,Vilaprisan ,Selective progesterone receptor modulator ,Follicular phase ,medicine ,Humans ,Female ,Steroids ,Pharmacology (medical) ,Receptors, Progesterone ,education ,business - Abstract
Aims We report population pharmacokinetic (popPK) and exposure-response (E-R) analyses for efficacy (induced amenorrhoea [IA]) and safety (unbound oestradiol [E2] concentrations) of the selective progesterone receptor modulator vilaprisan. Results were used to inform the dose for the Phase 3 programme in patients with uterine fibroids. Methods A popPK model was developed using data from Phase 1 and 2 studies (including ASTEROID 1 and 2). The relationship between vilaprisan exposure (steady-state AUC) and IA after oral administration of 0.5, 1, 2 or 4 mg/day over 3 months was analysed in ASTEROID 1 using logistic regression and qualified in ASTEROID 2 by comparing simulated and observed probability for IA after 2 mg/day. The exposure-E2 relationship was analysed visually. Results Vilaprisan clearance was 22.7% lower in obese vs non-obese patients. The E-R relationship for IA in ASTEROID 1 was steep and consistent with ASTEROID 2, with a maximum probability (Pmax ) of 59% (95% CI: 49-68%). The exposure at which 50% of Pmax is obtained was 36.9 μg*h/L (95% CI: 27.7-48.7 μg*h/L). Simulations showed that 36% of the patients will be below 90% of Pmax for IA after 1 mg/day compared to 2% after 2 mg/day. E2 levels tended to decrease with increasing exposure. While E2 levels remained largely within the physiologic follicular phase range, the clinical relevance of this decrease will be evaluated in long-term studies. Conclusions A 2 mg/day dose was selected for Phase 3 as E-R analyses show this dose results in a close to maximum probability for IA, without any safety concerns noted.
- Published
- 2021