Clinical Pharmacokinetics and Pharmacodynamics of the Selective Progesterone Receptor Modulator Vilaprisan: A Comprehensive Overview

Progesterone resistance in endometriosis: A pathophysiological perspective and potential treatment alternatives

Background

Endometriosis is a common gynecological disease affecting women of reproductive age. Patients with endometriosis frequently experience severe chronic pain and have higher chances to experience infertility. Progesterone resistance is a major problem that develops during the medical treatment of endometriosis, which often leads to treatment failure of hormonal therapies. Previous studies indicated that the dysregulation of progesterone receptors (PR) is the primary factor leading to progesterone resistance in endometriosis.

Methods

This review article systematically reviewed and summarized findings extracted from previously published papers available on PubMed, encompassing both experimental studies and clinical trials.

Main findings

Various determinants influencing PR expression in endometriosis have been identified, including the environmental toxins, microRNAs, cell signaling pathways, genetic mutations, and the pro-inflammatory cytokines. The selective estrogen/progesterone receptor modulators have emerged as novel therapeutic approaches for treating endometriosis, offering potential improvements in overcoming progesterone resistance.

Conclusion

Concerns and limitations persist despite the newly developed drugs. Therefore, studies on unraveling new therapeutic targets based on the molecular mechanisms of progesterone resistance is warranted for the development potential alternatives to overcome hormonal treatment failure in endometriosis.

Efficacy and safety of vilaprisan in women with uterine fibroids: data from the ASTEROID 3 randomized controlled trial

OBJECTIVE

Vilaprisan is a highly potent selective progesterone receptor modulator shown to reduce heavy menstrual bleeding, induce amenorrhea, and diminish uterine fibroid volume in phase 2 studies. The objective of ASTEROID 3 was to demonstrate the superiority of vilaprisan compared with placebo in the treatment of heavy menstrual bleeding in women with uterine fibroids.

DESIGN

Randomized, double-blind, placebo-controlled, multicenter phase 3 study.

SETTING

Hospitals and medical centers.

PATIENT(S)

Women with ≥1 uterine fibroid of ≥3 cm and heavy menstrual bleeding of >80 mL/cycle.

INTERVENTION(S)

Women were randomly assigned to 1 of 4 treatment arms, which were planned to comprise 2 treatment periods of 12 weeks, each with vilaprisan (2 mg/d) or placebo that were continuous or separated by a break of one bleed.

MAIN OUTCOME MEASURE(S)

Amenorrhea (primary end point; <2 mL in the last 28 days of treatment) and heavy menstrual bleeding response (key secondary end point; <80 mL/cycle and >50% reduction in bleeding from baseline) were measured with the alkaline hematin method. Change in volume of the 3 largest fibroids from baseline to end of treatment was assessed by ultrasound. Safety was monitored throughout the study.

RESULT(S)

Overall, 75 women completed the first 12 weeks of treatment. Statistically significant and clinically meaningful differences were observed between the vilaprisan- and placebo-treated groups in both the full analysis and per-protocol sets. In the per-protocol set (n = 36 and n = 12 for the vilaprisan and placebo groups, respectively), amenorrhea was observed more frequently in women treated with vilaprisan than in those who received placebo (83.3% vs. 0%, P<.0001), with a median time to onset of 3 days in the vilaprisan group. Similarly, more vilaprisan- than placebo-treated women achieved a response in heavy menstrual bleeding (91.7% vs. 25.0%, P<.0001). Serious adverse events were reported for 22 (27.8%) of 79 women and were evenly distributed among the 4 groups receiving vilaprisan and/or placebo. None of these events led to study discontinuation or were related to the liver, and no new safety findings were identified compared with the earlier phase 2 ASTEROID studies.

CONCLUSION(S)

Vilaprisan is efficacious and well tolerated over 12 weeks in the treatment of heavy menstrual bleeding associated with uterine fibroids. Further investigations of the long-term efficacy and safety of vilaprisan are warranted.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03400943 (ClinicalTrials.gov).

Single- and Multiple-Dose Pharmacokinetics and Safety of Vilaprisan in Healthy Postmenopausal Japanese Women: A Randomized Clinical Trial

BACKGROUND AND OBJECTIVES

As the prevalence of some gynecological conditions depends on patient characteristics such as race/ethnicity, it is important to study therapies for these conditions in diverse populations. The study described in this article was conducted to investigate the safety, tolerability, and pharmacokinetics of vilaprisan, a selective progesterone receptor modulator, in Japanese women in Japan. It supplements two comparable studies that were conducted in healthy postmenopausal European and Chinese women, respectively.

METHODS

In this exploratory randomized, placebo-controlled, double-blind, ascending-dose study, five groups of healthy postmenopausal Japanese women received vilaprisan as immediate-release tablets (1, 5, or 15 mg as a single dose or 1 or 5 mg/day for 28 days) or placebo tablets (single dosing: 8 subjects/dose step, thereof 2 subjects randomized to placebo; multiple dosing: 12 subjects/dose step, thereof 4 subjects randomized to placebo). Blood samples for pharmacokinetic profiles were collected over 14-19 days. Safety assessments were based on adverse event data, vital signs, electrocardiograms, clinical laboratory tests, and transvaginal ultrasound examinations.

RESULTS

48 participants were randomized, treated, and analyzed. Vilaprisan was rapidly absorbed, reaching maximum plasma concentrations (C_max) between 1 and 3 h post dose. Post maximum, plasma concentrations rapidly declined, indicating pronounced distribution into tissues. The exposure of vilaprisan increased roughly dose-proportionally: The geometric mean (geometric coefficients of variation) areas under the concentration time curves from time zero to infinity (AUC_∞) after single administration of 1, 5, or 15 mg vilaprisan were 67 µg·h/l (34%), 249 µg·h/l (15%), and 788 µg·h/l (37%), respectively. The AUC in the dosing interval after multiple administrations (AUC_24,md) of 1 mg/day was 76 µg·h/l (59%), and the AUC_24,md after 5 mg/day was 311 µg·h/l (20%). Geometric mean C_max values also increased roughly dose-proportionally: They amounted to 6 µg/l (22%), 16 µg/l (33%), and 52 µg/l (27%) after single administration and to 8 µg/l (28%) and 31 µg/l (22%) after multiple administrations of the above doses. Mild adverse events were observed, similar to those observed in other clinical studies of vilaprisan.

CONCLUSIONS

Overall, vilaprisan was safe and well tolerated. The exposure in Japanese women was similar to that observed in European and Chinese women in separate studies.

TRIAL REGISTRATION

15 Nov 2011 (no registration number assigned).