Thirty-day rat toxicity study reveals reversible liver toxicity of mifepristone (RU486) and metapristone

Mifepristone protects acetaminophen induced liver injury through NRF2/GSH/GST mediated ferroptosis suppression

Ferroptosis is a form of iron-dependent cell death that has attracted significant attention for its potential role in numerous diseases. Targeted inhibition of ferroptosis could be of potential use in treating diseases: such as drug induced liver injury (DILI). Ferroptosis can be antagonized by the xCT/GSH/GPX4, FSP1/CoQ10, DHODH/CoQ10, GCH1/BH4, and NRF2 pathways. Identifying novel anti-ferroptosis pathways will further promote our understanding of the biological nature of ferroptosis and help discover new drugs targeting ferroptosis related human diseases. In this study, we identified the clinically used drug mifepristone (RU486) as a novel ferroptosis inhibitor. Mechanistically, RU486 inhibits ferroptosis by inducing GSH synthesis pathway, which supplies GSH for glutathione-S-transferase (GST) mediated 4-HNE detoxification. Furthermore, RU486 induced RLIP76 and MRP1 export 4-HNE conjugate contributes to its anti-ferroptosis activity. Interestingly, RU486 induced GSH/GSTs/RLIP76&MRP1 anti-ferroptosis pathway acts independent of classic anti-ferroptosis systems: including xCT/GSH/GPX4, FSP1, DHODH, GCH1, SCD1 and FTH1. Moreover, NRF2 was identified to be important for RU486's anti-ferroptosis activity by inducing downstream gene expression. Importantly, in mouse model, RU486 showed strong protection effect on acetaminophen (APAP)-induced acute liver injury, evidenced by decreased ALT, AST level and histological recovery after APAP treatment. Interestingly, RU486 also decreased oxidative markers, including 4-HNE and MDA, and induced NRF2 activation as well as GSTs, MRP1 expression. Together, these data suggest NRF2/GSH/GST/RLIP76&MRP1 mediated detoxification pathway as an important independent anti-ferroptosis pathway act both in vitro and in vivo.

Repositioning of mifepristone as an integrated stress response activator to potentiate cisplatin efficacy in non-small cell lung cancer

Lung cancer, primarily non-small-cell lung cancer (NSCLC), is a significant cause of cancer-related mortality worldwide. Cisplatin-based chemotherapy is a standard treatment for NSCLC; however, its effectiveness is often limited due to the development of resistance, leading to NSCLC recurrence. Thus, the identification of effective chemosensitizers for cisplatin is of paramount importance. The integrated stress response (ISR), activated by various cellular stresses and mediated by eIF2α kinases, has been implicated in drug sensitivity. ISR activation globally suppresses protein synthesis while selectively promoting the translation of ATF4 mRNA, which can induce pro-apoptotic proteins such as CHOP, ATF3, and TRIB3. To expedite and economize the development of chemosensitizers for cisplatin treatment in NSCLC, we employed a strategy to screen an FDA-approved drug library for ISR activators. In this study, we identified mifepristone as a potent ISR activator. Mifepristone activated the HRI/eIF2α/ATF4 axis, leading to the induction of pro-apoptotic factors, independent of its known role as a synthetic steroid. Our in vitro and in vivo models demonstrated mifepristone's potential to inhibit NSCLC re-proliferation following cisplatin treatment and tumor growth, respectively, via the ISR-mediated cell death pathway. These findings suggest that mifepristone, as an ISR activator, could enhance the efficacy of cisplatin-based therapy for NSCLC, highlighting the potential of drug repositioning in the search for effective chemosensitizers.

Estradiol dominance induces hemodilution and mild hematological alterations in mifepristone-treated rats

We examined that an estradiol-dominant state against progesterone could affect hematological parameters through hemodilution because estradiol is known to increase plasma volume via oncotic pressure. We performed a 2- and 3-week repeated oral dose study with mifepristone, a progesterone receptor antagonist, in female rats and examined erythrocyte counts, hemoglobin, hematocrit, plasma volume, levels of estradiol and progesterone, water intake, and water loss. Mifepristone treatment decreased some hematological parameters mildly and increased plasma volume. There were no remarkable changes in the balance of water intake and water loss through urination. Both estradiol and progesterone levels and the ratio of estradiol to progesterone increased. Therefore, our findings indicate that repeated mifepristone treatment increases estradiol levels and plasma volume, resulting in lower erythrocyte counts, hemoglobin, and hematocrit. The present study proved the possible contribution of estradiol to understanding the toxicological significance of mifepristone-induced hemodilution.

PXR mediates mifepristone-induced hepatomegaly in mice

Mifepristone (Mif), an effective synthetic steroidal antiprogesterone drug, is widely used for medical abortion and pregnancy prevention. Due to its anti-glucocorticoid effect, high-dose Mif is also used to treat Cushing's syndrome. Mif was reported to active pregnane X receptor (PXR) in vitro and PXR can induce hepatomegaly via activation and interaction with yes-associated protein (YAP) pathway. High-dose Mif was reported to induce hepatomegaly in rats and mice, but the underlying mechanism remains unclear. Here, the role of PXR was studied in Mif-induced hepatomegaly in C57BL/6 mice and Pxr-knockout mice. The results demonstrated that high-dose Mif (100 mg · kg^-1 · d^-1, i.p.) treatment for 5 days significantly induced hepatomegaly with enlarged hepatocytes and promoted proliferation, but low dose of Mif (5 mg · kg^-1 · d^-1, i.p.) cannot induce hepatomegaly. The dual-luciferase reporter gene assays showed that Mif can activate human PXR in a concentration-dependent manner. In addition, Mif could promote nuclear translocation of PXR and YAP, and significantly induced the expression of PXR, YAP, and their target proteins such as CYP3A11, CYP2B10, UGT1A1, ANKRD, and CTGF. However, Mif (100 mg · kg^-1 · d^-1, i.p.) failed to induce hepatomegaly in Pxr-knockout mice, as well as hepatocyte enlargement and proliferation, further indicating that Mif-induced hepatomegaly is PXR-dependent. In summary, this study demonstrated that PXR-mediated Mif-induced hepatomegaly in mice probably via activation of YAP pathway. This study provides new insights in Mif-induced hepatomegaly, and provides novel evidence on the crucial function of PXR in liver enlargement and regeneration.

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

Vilaprisan is a highly potent selective progesterone receptor modulator in development for the treatment of symptomatic uterine fibroids and endometriosis. Its pharmacokinetics are characterized by rapid absorption, almost complete bioavailability, and dose-proportional exposure. The intrinsic factors of age, bodyweight, and race have no clinically relevant effect on the pharmacokinetics and pharmacodynamics of vilaprisan and do not warrant a dose adjustment. Similarly, vilaprisan can be used in patients with mild or moderate renal or hepatic impairment without dose adjustment, but its use is not recommended in patients with severe organ impairment. Vilaprisan has no perpetrator potential on cytochrome P450 (CYP) enzymes or transporters and therefore restrictions in the concomitant use of their substrates are not required. Nonetheless, because it is a sensitive CYP3A4 substrate itself, concomitant use of vilaprisan with strong CYP3A inhibitors or inducers is not recommended. However, there is no risk for QTc prolongation when vilaprisan and a strong CYP3A inhibitor are administered concomitantly, as indicated by a vilaprisan concentration–QTc response analysis across all studies with triplicate electrocardiogram measurements. Furthermore, due to its mode of action, vilaprisan is also not recommended to be used together with progestin-containing oral contraceptives. Vilaprisan shows a steep exposure–response relationship for inducing amenorrhea in patients with uterine fibroids experiencing heavy menstrual bleeding. Based on simulations, a dose of 2 mg/day is expected to induce a maximum bleeding reduction and was thus selected for phase III.

Pharmacokinetics, toxicological and clinical aspects of ulipristal acetate: insights into the mechanisms implicated in the hepatic toxicity

Ulipristal acetate is a drug used as emergency contraceptive (30 mg) and for the treatment of moderate to severe symptoms of uterine myomas (5 mg). After commercialization, and although the exact number is unknown, serious cases implying ulipristal acetate 5 mg as a contributing factor of liver injury, some leading to transplantation, were reported. These cases prompted to a restrict use of the drug in January 2021 by the European Medicines Agency. This work aimed to fully review pharmacokinetic aspects, namely focusing in the ulipristal acetate metabolism and other hypothetical toxicological underlying mechanisms that may predispose to drug-induced liver injury (DILI). The high lipophilicity, the extensive hepatic metabolism, the long half-life of the drug and of its major active metabolite, the long-term course of treatment, and possibility due to the formation of epoxide reactive may be contributing factors. Scientific results also points evidence to consider monitorization of liver function during ulipristal acetate treatment.

Acute liver failure requiring transplantation caused by ulipristal acetate

Ulipristal has recently been suspected to be hepatotoxic by the European Medicines Agency but the evidence base for hepatotoxicity is sparse. This is a brief formal report of a patient administered ulipristal for 6-8 weeks and who developed acute liver failure leading to liver transplantation. The explanted liver showed extensive hepatocyte necrosis and inflammation compatible with drug-induced liver injury and cirrhosis. The usual causes of acute hepatitis and cirrhosis were eliminated. There were no other potential causative drugs. This case suggests that ulipristal may cause acute hepatitis, with pre-existing cirrhosis probably contributing to the severity of liver injury observed in this case. Ulipristal prescribers must remain vigilant and monitor liver function in their patients.

The Selective Progesterone Receptor Modulator Ulipristal Acetate Inhibits the Activity of the Glucocorticoid Receptor

CONTEXT

The selective progesterone modulator ulipristal acetate (ulipristal) offers a much-needed therapeutic option for the clinical management of uterine fibroids. Although ulipristal initially passed safety evaluations in Europe, postmarketing analysis identified cases of hepatic injury and failure, leading to restrictions on the long-term use of ulipristal. One of the factors potentially contributing to significant side effects with the selective progesterone modulators is cross-reactivity with other steroid receptors.

OBJECTIVE

To determine whether ulipristal can alter the activity of the endogenous glucocorticoid receptor (GR) in relevant cell types.

DESIGN

Immortalized human uterine fibroid cells (UtLM) and hepatocytes (HepG2) were treated with the synthetic glucocorticoid dexamethasone and/or ulipristal. Primary uterine fibroid tissue was isolated from patients undergoing elective gynecological surgery and treated ex vivo with dexamethasone and/or ulipristal. In vivo ulipristal exposure was performed in C57Bl/6 mice to measure the effect on basal gene expression in target tissues throughout the body.

RESULTS

Dexamethasone induced the expression of established glucocorticoid-target genes period 1 (PER1), FK506 binding protein 51 (FKBP5), and glucocorticoid-induced leucine zipper (GILZ) in UtLM and HepG2 cells, whereas cotreatment with ulipristal blocked the transcriptional response to glucocorticoids in a dose-dependent manner. Ulipristal inhibited glucocorticoid-mediated phosphorylation, nuclear translocation, and DNA interactions of GR. Glucocorticoid stimulation of PER1, FKBP5, and GILZ was abolished by cotreatment with ulipristal in primary uterine fibroid tissue. The expression of glucocorticoid-responsive genes was decreased in the lung, liver, and uterus of mice exposed to 2 mg/kg ulipristal. Interestingly, transcript levels of Fkbp5 and Gilz were increased in the hippocampus and pituitary.

CONCLUSIONS

These studies demonstrate that ulipristal inhibits endogenous glucocorticoid signaling in human fibroid and liver cells, which is an important consideration for its use as a long-term therapeutic agent.

Mifepristone: An Uncommon Cause of Drug-Induced Liver Injury

Mifepristone is frequently used in large doses for management of Cushing’s syndrome. This is a case of a 35-year-old woman with Cushing’s syndrome, who presented with abdominal pain and jaundice. A month prior to admission, she had been started on a daily dose of 1,200 mg mifepristone. After evaluating for various other causes of liver injury, biopsy revealed cholestatic pattern of liver disease, likely associated with drug-induced hepatotoxicity. Mifepristone was discontinued and her symptoms resolved. We believe this is one of the first few reported cases of drug-induced liver injury (DILI) associated with mifepristone use.

Sex-related pharmacokinetic differences and mechanisms of metapristone (RU486 metabolite)

Metapristone is the primary metabolite of the abortifacient mifepristone (RU486), and is being developed as a safe and effective cancer metastatic chemopreventive agent for both sexes. Here, we systematically investigated the sex-related pharmacokinetics of metapristone in both rats and dogs, and explored the related mechanisms of actions. Administration of metapristone to rats and dogs showed that plasma concentrations of metapristone (AUC, C _max ) were significantly higher in female dogs and rats than in males. The sex-related differences in pharmacokinetics become more significant after ten consecutive days of oral administration. Female liver microsomes metabolized metapristone significantly slower than the male ones. The results from P450 reaction phenotyping using recombinant cDNA-expressed human CYPs in conjunction with specific CYP inhibitors suggested that CYP1A2 and CYP3A4 are the predominant CYPs involved in the metapristone metabolism, which were further confirmed by the enhanced protein levels of CYP1A2 and CYP3A4 induced by 1-week oral administration of metapristone to rats. The highest tissue concentration of metapristone was found in the liver. The study demonstrates, for the first time, the sex-related pharmacokinetics of metapristone, and reveals that activities of liver microsomal CYP1A2 and CYP3A4 as well as the renal clearance are primarily responsible for the sex-related pharmacokinetics.

Metapristone (RU486 derivative) inhibits cell proliferation and migration as melanoma metastatic chemopreventive agent

Uncontrolled cell proliferation and metastasis are the two well-known manifestations of melanoma. We hypothesized that metapristone, a potential cancer metastatic chemopreventive agent derived from mifepristone (RU486), had a dual function to fight cancer. In the present study, our findings clearly demonstrated that metapristone had modest cytostatic effect in melanoma cells. Metapristone inhibited cell viability and induced both early and late apoptosis in B16F10 and A375 cells in a time- and concentrate-dependent manner. Metapristone-treatment caused the cell arrest at the G0/G1 stage, and the inhibition of colony formation in B16F10 cells. Western blot analysis further revealed that metapristone treatment elicited a decline of Akt and ERK phosphorylation and Bcl-2, and facilitated expression of total P53 and Bax in A375 cells. In addition, cell migration and invasion were significantly suppressed by metapristone through down-regulating the expression of MMP-2, MMP-9, N-cadherin and vimentin, whereas up-regulating E-cadherin expression. Notably, metapristone exhibited anti-metastatic activity in melanoma B16F10 cells in vivo. Our results reveal metapristone, having the dual function of anti-proliferation and anti-migration for melanoma cell lines, may be a useful chemopreventive agent to reduce the risk of melanoma cancer metastasis.