Investigational developments for the treatment of progesterone-dependent diseases

Pharmacokinetics and Safety of the Selective Progesterone Receptor Modulator Vilaprisan in Chinese Healthy Postmenopausal Women

Vilaprisan is a novel selective progesterone receptor modulator for the long-term treatment of uterine fibroids and endometriosis. This study investigated the pharmacokinetics, safety, and tolerability of vilaprisan in healthy Chinese postmenopausal women. Twelve participants received multiple doses of vilaprisan once daily over 14 days as a 2-mg tablet. Plasma vilaprisan concentrations were determined using liquid chromatography-tandem mass spectrometry. The main pharmacokinetic parameters of vilaprisan were assessed with noncompartmental analysis, including maximum observed concentration (C_max ), systemic exposure (area under the plasma concentration-time curve), time to reach C_max and terminal half-life. Safety assessments include the documentation of adverse events, measurement of clinical/anthropometric parameters and vital signs, electrocardiogram, and physical and gynecologic examination. The participants had a mean age of 53.3 (± 4.2) years and a body mass index of 23.8 ± 2.8 kg/m² . Median time to reach C_max was 1.5 hours after both single and multiple vilaprisan administration. Mean C_max values obtained after multiple dosing (23.3 μg/L [standard deviation (SD) = 6.73]) were 1.92-fold (SD = 0.554) higher compared to single dosing (12.5 μg/L [SD = 3.04]). Mean area under the plasma concentration-time curve in the dosing interval increased with an accumulation factor of 2.98 (SD = 0.767) between single (91.3 μg · h/L [SD = 20.4]) and multiple dosing (276 μg · h/L [SD = 109]). The mean terminal half-life of vilaprisan was 44.5 hours (SD = 10.3) after multiple dosing. Mild to moderate adverse events were observed similar to previous studies. Overall, daily oral administration of the therapeutic dose of 2 mg of vilaprisan over 14 days was safe and well tolerated by all participants.

Discovery of Vilaprisan (BAY 1002670): A Highly Potent and Selective Progesterone Receptor Modulator Optimized for Gynecologic Therapies

Progesterone plays an important role in the female reproductive system. However, there is also evidence that gynecologic disorders/diseases such as uterine fibroids and endometriosis are progesterone-dependent. Steroidal and non-steroidal selective progesterone receptor modulators (SPRMs) have shown potential for the treatment of such diseases. Steroidal SPRMs, including mifepristone and ulipristal acetate, have proven effective in clinical trials. However, several steroidal SPRMs containing a dimethylamino substituent have been associated with elevated liver enzymes in patients. An earlier drug discovery program identified lonaprisan as a highly selective SPRM that did not show drug-related change in liver enzyme activity. Building on data obtained from that work, here we describe the research program that culminated in the discovery of a novel steroidal SPRM, vilaprisan, which combines an extremely high potency with very favorable drug metabolism and pharmacokinetic properties. Vilaprisan has entered clinical development and is currently undergoing phase 3 clinical trials.

Resistance to cisplatin and paclitaxel does not affect the sensitivity of human ovarian cancer cells to antiprogestin-induced cytotoxicity

Background

Antiprogestin compounds have been shown to be effective in blocking the growth of ovarian cancer cells of different genetic backgrounds. Herein we studied the anti-ovarian cancer effect of a series of antiprogestins sharing the chemical backbone of the most characterized antiprogestin, mifepristone, but with unique modifications in position C-17 of the steroid ring. We assessed the effect of mifepristone-like antiprogestins on the growth of ovarian cancer cells sensitive to the standard combination therapy cisplatin-paclitaxel or made double-resistant upon six cycles of pulse-selection with the drugs used at clinically relevant concentrations and exposure times.

Methods

IGROV-1 and SKOV-3 cells were pulsed with 20 μM cisplatin for 1 h followed by 100 nM paclitaxel for 3 h once a week for six weeks. The cells that did not die and repopulate the culture after the chemotherapies were termed Platinum-Taxane-EScape cells (PTES). Parental cells were compared against their PTES derivatives in their responses to further platinum-taxane treatments. Moreover, both ovarian cancer cells and their PTES siblings were exposed to escalating doses of the various antiprogestin derivatives. We assessed cell growth, viability and sub-G1 DNA content using microcapillary cytometry. Cyclin-dependent kinase inhibitors p21^cip1 and p27^kip1 and cleavage of downstream caspase-3 substrate PARP were used to assess whether cell fate, as a consequence of treatment, was limited to cytostasis or progressed to lethality.

Results

Cells subjected to six pulse-selection cycles of cisplatin-paclitaxel gave rise to sibling derivatives that displayed ~2-7 fold reduction in their sensitivities to further chemotherapy. However, regardless of the sensitivity the cells developed to the combination cisplatin-paclitaxel, they displayed similar sensitivity to the antiprogestins, which blocked their growth in a dose-related manner, with lower concentrations causing cytostasis, and higher concentrations causing lethality.

Conclusions

Antiprogestins carrying a backbone similar to mifepristone are cytotoxic to ovarian cancer cells in a manner that does not depend on the sensitivity the cells have to the standard ovarian cancer chemotherapeutics, cisplatin and paclitaxel. Thus, antiprogestin therapy could be used to treat ovarian cancer cells showing resistance to both platinum and taxanes.

Antiprogestin mifepristone inhibits the growth of cancer cells of reproductive and non-reproductive origin regardless of progesterone receptor expression

Background

Mifepristone (MF) has been largely used in reproductive medicine due to its capacity to modulate the progesterone receptor (PR). The study of MF has been expanded to the field of oncology; yet it remains unclear whether the expression of PR is required for MF to act as an anti-cancer agent. Our laboratory has shown that MF is a potent inhibitor of ovarian cancer cell growth. In this study we questioned whether the growth inhibitory properties of MF observed in ovarian cancer cells would translate to other cancers of reproductive and non-reproductive origin and, importantly, whether its efficacy is related to the expression of cognate PR.

Methods

Dose-response experiments were conducted with cancer cell lines of the nervous system, breast, prostate, ovary, and bone. Cultures were exposed to vehicle or increasing concentrations of MF for 72 h and analysed for cell number and cell cycle traverse, and hypodiploid DNA content characteristic of apoptotic cell death. For all cell lines, expression of steroid hormone receptors upon treatment with vehicle or cytostatic doses of MF for 24 h was studied by Western blot, whereas the activity of the G1/S regulatory protein Cdk2 in both treatment groups was monitored in vitro by the capacity of Cdk2 to phosphorylate histone H1.

Results

MF growth inhibited all cancer cell lines regardless of tissue of origin and hormone responsiveness, and reduced the activity of Cdk2. Cancer cells in which MF induced G1 growth arrest were less susceptible to lethality in the presence of high concentrations of MF, when compared to cancer cells that did not accumulate in G1. While all cancer cell lines were growth inhibited by MF, only the breast cancer MCF-7 cells expressed cognate PR.

Conclusions

Antiprogestin MF inhibits the growth of different cancer cell lines with a cytostatic effect at lower concentrations in association with a decline in the activity of the cell cycle regulatory protein Cdk2, and apoptotic lethality at higher doses in association with increased hypodiploid DNA content. Contrary to common opinion, growth inhibition of cancer cells by antiprogestin MF is not dependent upon expression of classical, nuclear PR.

Growth inhibition induced by antiprogestins RU-38486, ORG-31710, and CDB-2914 in ovarian cancer cells involves inhibition of cyclin dependent kinase 2

Antiprogestins have been largely utilized in reproductive medicine, yet their repositioning for oncologic use is rapidly emerging. In this study we investigated the molecular mediators of the anti-ovarian cancer activity of the structurally related antiprogestins RU-38486, ORG-31710 and CDB-2914. We studied the responses of wt p53 OV2008 and p53 null SK-OV-3 cells to varying doses of RU-38486, ORG-31710 and CDB-2914. The steroids inhibited the growth of both cell lines with a potency of RU-38486 > ORG-31710 > CDB-2914, and were cytostatic at lower doses but lethal at higher concentrations. Antiprogestin-induced lethality associated with morphological features of apoptosis, hypodiploid DNA content, DNA fragmentation, and cleavage of executer caspase substrate PARP. Cell death ensued despite RU-38486 caused transient up-regulation of anti-apoptotic Bcl-2, ORG-31710 induced transient up-regulation of inhibitor of apoptosis XIAP, and CDB-2914 up-regulated both XIAP and Bcl-2. The antiprogestins induced accumulation of Cdk inhibitors p21^cip1 and p27^kip1 and increased association of p21^cip1 and p27^kip1 with Cdk-2. They also promoted nuclear localization of p21^cip1 and p27^kip1, reduced the nuclear abundances of Cdk-2 and cyclin E, and blocked the activity of Cdk-2 in both nucleus and cytoplasm. The cytotoxic potency of the antiprogestins correlated with the magnitude of the inhibition of Cdk-2 activity, ranging from G1 cell cycle arrest towards cell death. Our results suggest that, as a consequence of their cytostatic and lethal effects, antiprogestin steroids of well-known contraceptive properties emerge as attractive new agents to be repositioned for ovarian cancer therapeutics.

Optimisation of a pyrazole series of progesterone antagonists; Part 1

The design and synthesis of a novel series of non-steroidal progesterone receptor antagonists is described. Ligand-lipophilicity efficiency (LLE) was used in the selection of a prototype agent for in vivo pharmacology studies.

Recent patent trends in the field of progesterone receptor agonists and modulators

BACKGROUND

Progesterone receptor agonists are used in female contraception, hormone replacement therapy or some gynecological conditions like endometriosis. The interest for antagonists or selective progesterone receptor modulators (SPRMs) is growing. Recent reports on this class of compounds indicate that they could become the next generation of therapeutics in gynecological treatments.

OBJECTIVE

This overview summarizes the work on progesterone receptor agonists, SPRMs and antagonists reported in the patent literature in the past 4 years.

METHODS

The focus of the article is the examination of patents, primarily published as WO, EU or US patents since 2005. In some cases, additional data from the public literature is included into the discussion. These data are of substantial interest as the available biological data disclosed in patents are usually limited for new compound classes.

RESULTS/CONCLUSION

Some highly active clusters of compounds have been disclosed in the past 4 years. The current research seems to focus on SPRMs and progesterone receptor antagonists.

Progesterone and mifepristone regulate L-type amino acid transporter 2 and 4F2 heavy chain expression in uterine leiomyoma cells

CONTEXT

Progesterone and its receptor (PR) play key roles in uterine leiomyoma growth. Previously, using chromatin immunoprecipitation-based cloning, we uncovered L-type amino acid transporter 2 (LAT2) as a novel PR target gene. LAT2 forms heterodimeric complexes with 4F2 heavy chain (4F2hc), a single transmembrane domain protein essential for LAT2 to exert its function in the plasma membrane. Until now, little is known about the roles of LAT2/4F2hc in the regulation of the growth of human uterine leiomyoma.

OBJECTIVE

The aim of the study is to investigate the regulation of LAT2 and 4F2hc by progesterone and the antiprogestin mifepristone and their functions in primary human uterine leiomyoma smooth muscle (LSM) cells and tissues from 39 premenopausal women.

RESULTS

In primary LSM cells, progesterone significantly induced LAT2 mRNA levels, and this was blocked by cotreatment with mifepristone. Progesterone did not alter 4F2hc mRNA levels, whereas mifepristone significantly induced 4F2hc mRNA expression. Small interfering RNA knockdown of LAT2 or 4F2hc markedly increased LSM cell proliferation. LAT2, PR-B, and PR-A levels were significantly higher in freshly isolated LSM cells vs. adjacent myometrial cells. In vivo, mRNA levels of LAT2 and PR but not 4F2hc were significantly higher in leiomyoma tissues compared with matched myometrial tissues.

CONCLUSION

We present evidence that progesterone and its antagonist mifepristone regulate the amino acid transporter system LAT2/4F2hc in leiomyoma tissues and cells. Our findings suggest that products of the LAT2/4F2hc genes may play important roles in leiomyoma cell proliferation. We speculate that critical ratios of LAT2 to 4F2hc regulate leiomyoma growth.

New drugs in development for the treatment of endometriosis

Endometriosis is a common and enigmatic disease causing pelvic pain and infertility. Current treatment is mainly based on the use of surgery and ovarian suppressive agents. There is in particular the need for new therapeutic options able to allow a normal menstrual cycle to occur and also consent pregnancy. In the present review, we aimed to give a concise and practical overview in order to allow the clinician to clearly understand the level of development of these drugs. We have presented only treatments supported by in vivo researches with a special attention to studies in humans. Results show appealing new possibilities are emerging from agents counteracting the endometriosis-associated inflammation. Recent data also suggests that there is still the opportunity to refine the use of already available agents.