Antiandrogen Research Articles

Prognostic role of Androgen Receptor splice variant 7 (AR-V7) in the pathogenesis of breast cancer.

The Androgen Receptor (AR) has emerged as an endocrine therapy target in Breast Cancer, exhibiting up to 80% expression in clinical cases. AR-V7, a constitutively activated splice variant of AR with a truncated ligand-binding domain (LBD), demonstrates ligand-independent transcriptional activity and resistance to nonsteroidal antiandrogens like Bicalutamide or Enzalutamide, targeting the LBD. In metastatic prostate cancer, elevated AR-V7 levels lead to therapeutic resistance and increased metastasis. In this study, we evaluated the expression of AR and AR-V7 in cell lines and a cohort of 89 patients undergoing surgical intervention for treatment-naïve breast cancer. Further clinicopathological correlations and survival analysis were performed to evaluate the relationship between the AR and AR-V7 expression and clinical outcomes. AR-V7/AR-FL ratio was elevated in the TNBC cell line and downregulation of AR-FL upon AR antagonists' treatment led to a compensatory increase in AR-V7. Clinical samples showed significantly elevated expression of AR and AR-V7 in tumors compared to control cases. Further clinicopathological correlation revealed aggressive clinical traits, higher pathological grades, and poor survival with AR-V7 expression. Our study unravels AR-V7 as a marker for poor clinical outcomes, predicting breast cancer aggressiveness, and encourages consideration of AR-V7 as a probable target for therapeutic intervention.

Vaccination Against Androgen Receptor Splice Variants to Immunologically Target Prostate Cancer

Background/Objectives: Androgen receptor (AR) expression and signaling are critical for the progression of prostate cancer and have been the therapeutic focus of prostate cancer for over 50 years. While a variety of agents have been developed to target this axis, many of these fail due to the emergent expression of AR RNA splice variants, such as AR-V7, that can signal independently of ligand binding. Other therapies, such as vaccination against prostate-specific antigens, have achieved FDA approvals but have fallen short of being incorporated as standard-of-care therapies for advanced prostate cancer. This may be due to the elevated level of immunosuppression observed in prostate cancer, which remains largely refractory to immune checkpoint blockade. Methods: We developed a vaccine targeting AR-V7, a common isoform associated with treatment resistance, and demonstrated its ability to elicit AR-V7-specific immunity and enable anti-tumor responses against AR-V7+ cancers in subcutaneous tumor models. Results: Our studies also revealed that AR-V7 expression conferred an immune suppressive phenotype that was significant in a non-AR-dependent prostate cancer model. Notably, in this model, we found that vaccination in combination with enzalutamide, an AR antagonist, suppressed these aggressive immune suppressive cancers and resulted in enhanced survival in comparison to control vaccinated and enzalutamide-treated mice. While anti-PD-1 immune checkpoint inhibition (ICI) alone slowed tumor growth, the majority of vaccinated mice that received anti-PD-1 therapy showed complete tumor elimination. Conclusions: Collectively, these results validate the importance of AR signaling in prostate cancer immune suppression and suggest the potential of AR-V7-specific vaccines as therapeutic strategies against prostate cancer, offering significant protective and therapeutic anti-tumor responses, even in the presence of androgen signaling inhibitors.

An Autophagy-Targeting Chimera Induces Degradation of Androgen Receptor Mutants and AR-v7 in Castration-Resistant Prostate Cancer.

Genetic alterations play a pivotal role in various human diseases, particularly cancer. The androgen receptor (AR) is a crucial transcription factor driving prostate cancer (PCa) progression across all stages. Current AR-targeting therapies utilize competitive AR antagonists or pathway suppressors. However, therapy resistance often emerges due to AR mutations and AR splice variants, such as AR-v7. To overcome this, we developed ATC-324, an AR degrader using the innovative protein degradation technology platform AUTOphagy-TArgeting Chimera (AUTOTAC). ATC-324 was designed to comprise enzalutamide, an AR inhibitor, as a target-binding ligand and YT 6-2, a ligand of the autophagy receptor p62/SQSTM1, as an autophagy-targeting ligand. ATC-324 induces the formation of the AR/p62 complex, leading to autophagy-lysosomal degradation of AR. Importantly, ATC-324 effectively degrades AR mutants frequently detected in PCa and co-degrades AR-v7 as a heterodimer with full-length AR. ATC-324 reduces nuclear AR levels and downregulates the target gene expression of AR and AR-v7, leading to cytotoxicity in AR-positive PCa cells. We also provide evidence of the therapeutic potential of ATC-324 in vivo as well as ex vivo bone organ culture. Moreover, ATC-324 remains potent in enzalutamide-resistant PCa cells. These results demonstrate the potential of the AUTOTAC platform to target previously considered undruggable proteins and overcome certain drug resistance mechanisms.

DDDR-32. EXPLORING ANDROGENIC MODULATION IN GLIOBLASTOMA: POTENCY AND SELECTIVITY OF NOVEL NORETHINDRONE DERIVATIVES

Abstract BACKGROUND Glioblastoma (GBM) represents the most frequently diagnosed malignant CNS tumor in adults and remains incurable. Despite the identification of several oncogenic drivers contributing to tumor formation, targeted therapy with brain-penetrant inhibitors has afforded little progress in survival outcomes. Interestingly, gender has been shown to increase the incidence of GBM, with men having roughly a 50-60% increase in incidence compared to women in the US. This statistic led to research on the involvement of and subsequent inhibition of androgen synthesis and signaling in cell culture models and tumor samples. METHODS To further investigate the potential involvement of steroidal hormones in GBM proliferation, our lab synthesized a series of norethindrone (NE) derivatives with varied molecular weights, steric bulk, and lipophilicity to modulate the androgenic activity of NE. The small library was tested in several GBM cell lines, including U87, A172, and T98G cells, using cell viability assays. RESULTS One derivative, a lipophilically modified version of NE synthesized via a one-pot click reaction, was shown to have improved potency compared with parental NE (>5-fold). The lipophilic NE derivative had IC50 value of 22 uM, 15 uM, and 35 uM in the U87, A172, and T98G cells, respectively. This molecule was tested in immortalized normal human astrocyte (NHA) cells and found to have an IC50 value of 34 uM suggesting some selectivity. DISCUSSION Given this derivative’s activity in GBM models and modest selectivity, we plan to screen it in additional GBM cell lines (LN-18 and U251) and eventually in glioma stem cell models. Future research will focus on identifying key targets involved in the mechanism of action, including the impact of lipophilic addition to the steroid nucleus and its effect on androgenic activity and downstream signaling. We will investigate these effects using RPPA and co-treatments with androgen receptor antagonists and 5-alpha reductase inhibitors.

Scaffold transforming and in-silico design of potential androgen receptor antagonists in prostate cancer therapy.

Androgens like testosterone and dihydrotestosterone are essential for the growth and development of the prostate gland. Androgenic receptors are overexpressed, which promotes the progression of prostate cancer; therefore, androgenic receptors are a key target in the therapy of prostate cancer. Enzalutamide is used to treat prostate cancer; however, it also causes toxicities such as cardiovascular toxicity, acute myocarditis, hypertension, and seizures. The objective of this research was to create novel and safer analogues of enzalutamide, followed by the prediction of the pharmacokinetic and toxicity characteristics of these enzalutamide analogues. Molecular docking studies of analogues were also done to guess how ligands will work biologically in treating prostate cancer. A total of 195 analogues were generated, and among them, 23 bioisosteres were selected for further pharmacokinetic, toxicological screening and docking studies. The predicted physical-chemical, medicinal, and ADMET characteristics of the designed bioisosteres were optimal to good compared to enzalutamide. Additionally, the drug likeness and drug score of analogues were superior to enzalutamide. According to docking studies of analogues, EZ12, EZ8, and EZ10 formed hydrogen bonds of SER778 with replaceable amide groups in enzalutamide molecules. SER778 residue may be responsible for antagonistic activity towards androgen receptors. Based on the results of the ADMET, drug likeness, drug score, and docking study of designed enzalutamide analogues, the ligands EZ12, EZ8, and EZ10 could be used to find more possible antiandrogen drugs that could be used to treat prostate cancer.

Discovery of 5-Nitro-N-(3-(trifluoromethyl)phenyl) Pyridin-2-amine as a Novel Pure Androgen Receptor Antagonist against Antiandrogen Resistance.

The transformation of clinical androgen receptor (AR) antagonists into agonists driven by AR mutations poses a significant challenge in treating prostate cancer (PCa). Novel anti-AR therapeutics combating mutation-induced resistance are required. Herein, by combining structure-based virtual screening and biological evaluation, a high-affinity agonist E10 was first discovered. Then guided by the representative conformation of State 1 at the free energy landscape, the structural optimization of E10 was performed, and pure AR antagonists EL15 (IC50 = 0.94 μM) and EF2 (IC50 = 0.30 μM) were successfully identified. Both can antagonize wild-type and variant drug-resistant ARs. Therein, EF2 demonstrated potent inhibition of the AR pathway and effectively suppressed tumor growth in a C4-2B xenograft mouse model following oral administration. Further molecular dynamics simulation and mutagenesis studies revealed atomic insights into the mode of action of EF2 which may serve as a novel lead compound for developing therapeutics against AR-driven PCa.

Identification of Oral Bioavailable Coumarin Derivatives as Potential AR Antagonists Targeting Prostate Cancer.

Androgen receptor (AR) is a crucial driver of prostate cancer (PCa), but acquired resistance to AR antagonists significantly undermines their clinical efficacy. We previously discovered coumarin derivative 1, which is capable of disrupting AR ligand-binding domain dimers, offering the potential for overcoming resistance. However, its poor oral bioavailability limited further development. In this study, comprehensive structure optimizations led to compound 4a (IC50 = 0.051 μM), which exhibited comparable AR antagonistic activity to enzalutamide (IC50 = 0.060 μM) and demonstrated excellent selectivity over other nuclear receptors in vitro. Especially, 4a showed superior efficacy against ARF876L/T877A and ARW741C mutants compared to darolutamide and enzalutamide. Moreover, 4a exhibited favorable pharmacokinetic profiles (F = 66.24%) in vivo and significant tumor growth inhibition in an LNCaP xenograft mouse model upon oral administration. These results highlight the potential of 4a as a promising oral AR antagonist for overcoming drug resistance in PCa.

Peripubertal exposure to oxyfluorfen, a diphenyl herbicide, delays pubertal development in the male rat by antagonizing androgen receptor activity.

We recently identified the herbicide oxyfluorfen as an inhibitor of iodide uptake by the sodium iodide symporter (NIS), a key step in thyroid hormone synthesis, using in vitro assays. We also observed a suppression of serum T4 and T3 in juvenile rats exposed orally to oxyfluorfen for 4-8 days. The purpose of the present study was to further evaluate effects of an extended 31-day oral exposure using a male pubertal rat study (15 to 500 mg/kg). Oxyfluorfen delayed puberty at all doses (1.3 -3.5 days) suppressing ventral prostate at 62.5 mg/kg and above and seminal vesicle weights at 31.25 mg/kg and above with no effect on testosterone or luteinizing hormone. Serum T4 and T3 were suppressed by all doses up to 80%, with a linear increase in serum TSH. Based on delayed puberty without changes in testosterone, we hypothesized that oxyfluorfen interferes with androgen receptor (AR) function. Results from our Hershberger study, with oxyfluorfen (62.5 and 125 mg/kg) co-treated with testosterone proprionate (TP , 1 mg/kg) for 10 days showed 3 of 5 of the androgenic tissue weights were suppressed compared to TP alone indicating AR antagonism. We next confirmed this effect in an in vitro AR transcriptional activation reporter assay (0-20 μM) with 125 pM 5αDH-11-ketotestosterone and found concentration-dependent inhibition of AR luminescence activity (EC50 1.75 µM) without cytotoxicity. Here, we confirmed the endocrine disrupting effects of oxyfluorfen using both in vitro and in vivo evaluations of the thyroid hormone and AR pathways. This abstract doesn't necessarily reflect U.S. EPA policy.

A case of primary duodenal Brunner's gland hamartoma that gradually underwent morphological changes over a period of 10 years.

Brunner's gland hamartoma (BGH) is a benign tumor occurring in the duodenal bulb. BGH is typically asymptomatic, but it has been shown to occasionally cause anemia. The patient was a 76-year-old male. In October 2011, he was diagnosed with prostate cancer with multiple bone metastases and was referred to us for the treatment and examination of anemia. Hormonal therapy with androgen receptor antagonists and bisphosphonate administration following orchiectomy improved his symptoms. In August 2012, esophagogastroduodenoscopy (EGD) was performed due to stomach discomfort, revealing a 5 mm semi-pedunculated polyp in the duodenal bulb, Yamada-Fukutomi classification type II. Over the next 5 years, the prostate cancer treatment proceeded smoothly, and no endoscopic follow-up was conducted. In January 2017, during a health checkup, EGD revealed that the polyp in the duodenum bulb had changed morphologically with a distinct stalk measuring 10 mm. As there were no symptoms and only minimal tumor growth, a watchful waiting approach was adopted. In April 2022, due to the rapid progression of anemia, EGD was performed again, showing that the pedunculated polyp had enlarged to 20 mm in maximum diameter with an eroded surface and a stalk extending to 40 mm. Given the tumor enlargement and further examination of anemia, an endoscopic polypectomy was performed in May 2022. Histopathological examination confirmed the diagnosis of BGH. We observed a case of primary duodenal BGH during treatment for advanced prostate cancer, with endoscopic monitoring over 10 years. The morphological changes of BGH were clearly documented via EGD.

The Effect of Androgen Deprivation Therapy on the Cardiovascular System in Advanced Prostate Cancer

Androgen deprivation therapy (ADT) is a mainstay treatment for metastatic prostate cancer, improving progression-free survival. ADT suppresses the production of testosterone and reduces circulating levels of the hormone. Luteinizing hormone-releasing hormone (LH-RH) agonists are the most commonly used ADT modality. They can be given alone or in combination with androgen synthesis inhibitors or androgen receptor antagonists. An estimated 40% of prostate cancer patients will receive ADT as part of their therapy during their lifetime. However, ADT has numerous adverse effects, including an increased cardiovascular risk that impacts quality of life. Relugolix is an alternative form of ADT. It is the only oral gonadotropin-releasing hormone antagonist, circumventing injection site reactions, making it easier for patients to take, and thus increasing compliance. Testosterone suppression with relugolix is excellent and testosterone recovery after discontinuation is rapid. This paper reviews the ADT and anti-androgen treatment options for men with prostate cancer and the cardiovascular effects of these therapies. There is accumulating evidence that cardiovascular risk with relugolix is lower than with other ADT medications and also lower than with androgen synthesis inhibitors and androgen receptor antagonists. This paper provides insight into the use of different ADT regimens based on the cardiovascular status and circumstances. It explores strategies to mitigate negative cardiovascular consequences and highlights the need for further study.

Falls and fractures in men with prostate cancer taking second-generation androgen receptor antagonists: A retrospective chart review.

Second-generation androgen receptor antagonists, including enzalutamide, apalutamide, and darolutamide, are commonly used to treat metastatic and non-metastatic prostate cancer. Although these medications are typically well-tolerated, falls were reported in 4.2-15.6% of patients and fractures in 4.2-11.7% of patients enrolled in the phase III clinical trials evaluating these drugs in prostate cancer. However, post-marketing studies have reported a lower incidence than reported in clinical trials. The objective of this study is to determine the prevalence of falls and fractures in patients with prostate cancer receiving second-generation androgen receptor antagonists at UConn Health and identify potential risk factors associated with falls and fractures in these patients. A retrospective chart review involving patients with prostate cancer treated with darolutamide, enzalutamide, or apalutamide from March 1, 2022, to March 31, 2023, at UConn Health Carole & Ray Neag Comprehensive Cancer Center. Data recorded includes basic demographics, history of fall or fracture, presence of metastases, fall risk, history of osteoporosis, prescribed second-generation androgen receptor antagonist, and other comorbidities. Data was evaluated using descriptive statistics. Twenty-six men were included, all of whom were receiving enzalutamide. At baseline, 96.1% of patients had bone metastases, 15.4% had osteoporosis, 15.4% had osteopenia, and 34.6% had neuropathy. The incidence of falls was 19.2% and the incidence of fractures was 26.9%. The mean length of therapy at time of a fall was 19.44 months (range, 6-31 months). The mean length of therapy at time of a fracture was 19 months (range, 1-33 months). In patients experiencing fall, 100% had arthralgia, 60% had neuropathy, 40% had a gait problem, 40% had hypertension, and 80% of them were at risk of fall. In patients experiencing fracture, 28.6% had osteoporosis, 42.9% had osteopenia, 100% had bone metastases, and 57.1% were on denosumab at time of fracture. The prevalence of falls and fractures in patients receiving enzalutamide were higher in this retrospective chart review than reported in clinical trials and post-marketing studies. This could be due to the small patient population or the patient's comorbidities such as osteoporosis, bone metastases, or neuropathy. Fall/fracture risk with enzalutamide and other risk factors for fall and fracture should be considered when discussing treatment and developing a monitoring plan.

Preliminary Efficacy, Tolerability, and Safety Analysis of Darolutamide for Metastatic Castration-Resistant Prostate Cancer: A Single-Center, Open-Label Study

Introduction: Darolutamide is a structurally unique second-generation androgen receptor antagonist that has been approved for indications in patients with non-metastatic castration-resistant prostate cancer (nmCRPC) and metastatic hormone-sensitive prostate cancer (mHSPC). The aim was to assess the efficacy and safety of Darolutamide for mCRPC. Methods: In this single-center, open-label study, patients with previously untreated mCRPC were enrolled and received androgen deprivation therapy (goserelin acetate 3.6 mg every 28 days) and docetaxel (75 mg per square meter of body surface area every 21 days) with Denosumab (120 mg every 28 days) for bone metastases, Darolutamide (300 mg orally twice daily) in the experimental group, and the control group received the corresponding of placebo. Serum PSA changes were detected and recorded, and imaging changes and adverse events (AEs) were evaluated. The primary endpoints were safety, tolerability, and antitumor efficacy, and the second endpoint was radiographic progression-free survival (rPFS). Results: Thirty-seven patients with mCRPC were enrolled. The median time to PSA50 in the Darolutamide group was 1.5 months (95% CI: 0.2619–0.9545), significantly lower than that in the placebo group (3.0 months [95% CI: 1.048–3.818], p = 0.0259). The median time to PSA90 in the experimental group was 4 months (95% CI: 0.3094–1.437), 2 months shorter than that in the placebo group (6.0 months [95% CI: 0.6961–3.232]). With the median follow-up of 6 months, the median decrease in serum PSA was −81.8% (range −60.4 to −99.9%) in the Darolutamide group and −69.4% (range −50.3 to −89.6%) in the placebo group. Tumor-related pain and AEs were not increased, and the median rPFS was not reached. Conclusions: The combination of Darolutamide and docetaxel was well tolerated with more clinically beneficial than docetaxel alone in previously untreated mCRPC. Darolutamide rapidly reduced PSA levels and prolonged rPFS and did not increase the incidence of AEs.

Targeted Delivery of AR-V7 siRNA with Bivalent PSMA Aptamers Effectively Suppresses the Growth of Enzalutamide-Resistant Prostate Cancer.

Androgen deprivation therapy has been the primary treatment strategy for advanced prostate cancer (PCa). But most patients develop castration resistance over time. For FDA-approved second-generation androgen receptor (AR) antagonists, including enzalutamide (ENZ) and abiraterone (AA), patients who initially respond to them eventually develop resistance. The key mechanism for resistance to ENZ/AA involves AR splice variants (AR-Vs) and specifically AR-V7. Current AR antagonists cannot target AR-V7 due to its lack of the C-terminal ligand-binding domain (LBD) but keeping the AR N-terminal domain (NTD) which still can activate androgen-responsive genes. Therefore, targeting the AR NTD and AR-V7 is critically important to overcome ENZ resistance. Unfortunately, AR NTD has been considered an "undruggable" target due to the difficulty in defining its three-dimensional (3D) structure. In this context, siRNA is highly suitable to address this undruggable target. However, siRNA cannot freely diffuse into cells, and a carrier is needed. In this regard, nucleic acid-based aptamers are highly suitable for cell type-specific delivery of siRNA in vivo. In this study, we have developed a serum-stable bivalent prostate-specific membrane antigen (PSMA) aptamer-AR-V7 siRNA chimera (PAP). The results show that PAP can knock down both AR-full length and AR-V7 in PSMA-expressing castration-resistant cells. It can resensitize ENZ in cell lines and PCa xenografts. ENZ combined with PAP can significantly inhibit 22Rv1 xenograft growth in mice without experiencing castration. Owing to the low toxicity, PAP has potential to offer a new antiandrogen treatment for current ENZ-resistant PCa.

7288 A Preclinical Mouse Model of Gender-Affirming Hormone Therapy: Metabolic and Behavioral Outcomes

Abstract Disclosure: A. Yasrebi: None. K. Otersen: None. O. Groh: None. E. Guthman: None. I. Shmarakov: None. S. Campbell: None. T.A. Roepke: None. The long-term metabolic effects of gender-affirming hormone therapy (GAHT) is largely unknown, in part, due to the lack of properly designed preclinical animal models. Here we propose a rodent study design, beyond the classical endocrine model of gonadectomy and steroid treatment, to accurately reflect the reality of the trans experience. Specifically, trans women do not all seek or undergo orchidectomy (ORX) instead take estrogen supplementation along with an androgen blocker such as finasteride. In this study, 40 WT C57 male mice were divided into 4 groups of 10 mice - 1) intact with oil vehicle, 2) intact with estradiol benzoate (EB, 150 μg/kg/d) and finasteride (F, 0.25 mg/kg/d), 3) ORX with oil; and ORX with EB (150 μg/kg/d). Each mouse was dosed daily for 8 weeks while on a standard chow diet. Mice were pair housed and food intake and body weight were collected weekly prior to behavioral (open field, elevated plus, Y-maze) and metabolic (body composition, metabolic rates, activity, tolerance testing) phenotyping. Intact mice treated with EB+F exhibited less avoidance behaviors, potentially due to differences in movement, with no differences between treatments in the Y-maze. Cumulatively, Intact:EB+F gained less weight than Intact:oil (3.4 ± 0.4 g vs 5.3 ± 0.4 g), while ORX:oil mice gained less than ORX:EB (2.2 ± 0.5 g vs 5.5 ± 0.7 g). These interactive effects were due to differences in the gain of fat or lean mass between ORX and intact and lower cumulative food intake in ORX:oil mice (136 ± 3.8 g vs Intact:oil: 159 ± 4.9 g; Intact:EB+F: 167 ± 6.1 g; ORX:EB: 171 ± 3.4 g). Metabolic assessments found that Intact:EB+F exhibited elevated V.O2, V.CO2, and heat production in the light and dark cycle compared to Intact:oil, while ORX:EB only exhibited elevated heat production compared to ORX:oil. Similarly, Intact:EB+F and ORX:EB moved more than their counterparts during the dark cycle; however, only Intact:EB+F exhibited elevated wheel running. Tolerance tests (i.p.) found that glucose clearance was augmented in ORX:EB mice while insulin-induced glucose clearance was lower in Intact:EB+F compared to Intact:oil but modestly elevated by EB in ORX mice. These data, along with suppressed fasting blood glucose in ORX:EB mice, suggest that glucose homeostasis is differentially modulated by GAHT paradigms in mice. Analysis of hypothalamic, hepatic, adipose, and intestinal gene expression is currently underway. Collectively, these data, generated by using a translationally-relevant preclinical animal model, are the first to establish that metabolism is differentially affected by both steroid treatments and ORX and suggesting that the long-term metabolic effects of GAHT are dependent on the type of treatment. The underlying mechanisms and sites of action remain to be investigated. Presentation: 6/3/2024

5065 Cyproterone Acetate Versus Spironolactone In Transgender Women Commencing Estradiol: A Randomized Controlled Trial

Abstract Disclosure: L.M. Angus: Advisory Board Member; Self; Kirin Brewery. Speaker; Self; Kirin Brewery. S. Leemaqz: None. A. Kasielska-Trojan: None. M. Mikołajczyk: None. J. Doery: None. J.D. Zajac: None. A.S. Cheung: None. Background: Transgender women commonly use cyproterone acetate or spironolactone as anti-androgens with estradiol to assist with feminization. However, the optimal anti-androgen is unclear. We aimed to assess the effect of these anti-androgens on breast development and hypothesized that cyproterone acetate would result in greater breast development than spironolactone due to greater androgen receptor antagonism and suppression of serum total testosterone. Design: Double-blind, randomised controlled trial Methods: Transgender women newly commencing estradiol were randomized to spironolactone 100mg daily or cyproterone acetate 12.5mg daily for six months. The primary outcome was measurement of breast development via breast chest distance with secondary outcomes of estimated breast volume using the BreastIdea Volume Estimator application and serum total testosterone using LCMS. Results: Fifty-five participants were included in per protocol analysis (cyproterone acetate group n=28, spironolactone group n=27). Baseline age, body mass index, breast indices, serum estradiol and serum total testosterone were comparable. At six months, the mean (standard deviation) breast chest distance was 9.2cm (3.0) in the cyproterone group versus 8.3cm (2.7) in the spironolactone group (p=0.27). The mean (SD) estimated breast volume was 190.25 mL (158.60) in the cyproterone acetate group and 157.84mL (112.03) in the spironolactone group (p=0.39) with significant inter-individual variation (range 20.27 - 787.77 mL). The mean (SD) serum total testosterone was 1.48 nmol/L (3.45) in the cyproterone acetate group and 4.29 nmol/L (5.44) in the spironolactone group (p=0.04). Serum estradiol levels were comparable. Use of cyproterone acetate was associated with mild hyperprolactinaemia and spironolactone with an increase in serum urea and creatinine. Conclusions: Choice of anti-androgen should be individualised based on clinician and patient preference, with consideration of associated side effects. Further research is needed to optimise breast development in transgender women. Presentation: 6/3/2024

Population Pharmacokinetics Modeling and Simulation of Deutenzalutamide, A Novel Androgen Receptor Antagonist, in Patients With Metastatic Castration-Resistant Prostate Cancer.

Deutenzalutamide is a new molecular entity androgen receptor antagonist. The primary aim of this study was to develop a population pharmacokinetic model of deutenzalutamide and evaluate effects of intrinsic and extrinsic factors on pharmacokinetics. A nonlinear mixed-effects modeling approach was performed to develop the population pharmacokinetic of deutenzalutamide using data from 1 Phase I trial of deutenzalutamide. Goodness-of-fit plots, prediction-corrected visual predictive check, and bootstrap analysis were carried out to evaluate the final model. Simulation for the developed model was used to evaluate the covariate effects on the pharmacokinetics of deutenzalutamide. A 2-compartment model with first-order absorption and elimination from the central compartment was established for deutenzalutamide. The final covariate included body weight on peripheral compartment volume. This is the first research developing the population pharmacokinetic model of deutenzalutamide in patients with metastatic castration-resistant prostate cancer, and it is expected to support the future clinical administration of deutenzalutamide.

Profiling the endocrine disrupting properties of triazines, triazoles and short-chain PFAS.

Persistent, mobile and toxic (PMT) compounds released to the environment are likely to pollute drinking water sources due to their slow environmental degradation (persistency) and high water solubility (mobility). The aim of the present study was to create in vitro hazard profiles for sixteen triazoles, nine triazines and eleven PFAS based on their agonistic and antagonistic effects in estrogen receptor (ER), androgen receptor (AR) and thyroid hormone receptor (TR) reporter gene assays, their ability to bind human transthyretin (TTR), and their effects on steroidogenesis. The triazole fungicides tetraconazole, bitertanol, fenbuconazole, tebuconazole, cyproconazole, difenoconazole, propiconazole, paclobutrazol and triadimenol had agonistic or antagonistic effects on the ER and AR. Difenoconazole, propiconazole and triadimenol were also found to be TR antagonists. The triazine herbicide ametryn was an ER, AR and TR antagonist. The same nine triazole fungicides and the triazines atrazine, deethyl-atrazine and ametryn affected the secretion of steroid hormones. Furthermore, PFAS compounds PFBS, PFHxS, PFHxA, PFOS, PFOA and GenX and the triazoles bitertanol, difenoconazole and 4-methyl benzotriazole were found to displace T4 from TTR. These results are in line with earlier in vitro and in vivo studies on the endocrine disrupting properties of triazines, triazoles and PFAS. The present study demonstrates that this battery of in vitro bioassays can be used to profile compounds from different classes based on their endocrine disrupting properties as a first step to prioritize them for further research, emission reduction, environmental remediation and regulatory purposes.

Androgen receptor regulates the differentiation of myoblasts under cyclic mechanical stretch and its upstream and downstream signals

Our previous studies have demonstrated the important roles of androgen receptor (AR) in myoblast proliferation regulated by 15 % (mimic appropriate exercise) and 20 % (mimic excessive exercise) mechanical stretches. Except for myoblast proliferation, differentiation is also an important factor affecting muscle mass and strength. But the role of AR in stretch-regulated myoblast differentiation and AR's upstream and downstream signals remain unknown. In the present study, firstly the differences of myogenic differentiation between C2C12 (with AR expression) and L6 (without AR expression) myoblasts induced by 15 % and 20 % mechanical stretches were compared; secondly, AR antagonist flutamide and AR agonist GTx-007 were used in 15 % and 20 % stretched myoblasts respectively to confirm AR's roles in stretch-regulated myoblast differentiation; thirdly, RNA-seq, molecular dynamic simulation (MD) and co-immunoprecipitation were performed to screen the downstream and upstream molecules of AR during stretches. We found that (1) 15 % stretch increased while 20 % stretch decreased myotube number in differentiating C2C12 and L6 myoblasts, with more significant changes in C2C12 cells than L6 cells; (2) in stretched C2C12 myoblasts, AR antagonist flutamide inhibited 15 % stretch-promoted differentiation while AR agonist GTx-007 reversed 20 % stretch-inhibited differentiation (reflected by changes in myotube number, MHC contents of fast-twitch and slow-twitch fiber, and the levels of myogenic regulatory factors (MRFs) such as MyoD and myogenin); (3) KEGG analysis of RNA-seq showed that the differently expressed genes (DEGs) in C2C12 cells induced by 15 % stretch were enriched in FoxO and JAK-STAT signaling pathways, while DEGs by 20 % stretch were enriched in FoxO and MAPK signaling pathways; (4) MD and co-immunoprecipitation showed that β1 integrin could interact with AR and influence AR's activity in C2C12 cells. In conclusion, AR plays important roles in myoblast differentiation promoted by 15 % stretch while inhibited by 20 % stretch, which was fulfilled through FoxO-MRFs. In addition, α7β1 integrin may be a bridge linking mechanical stretch and AR. This study is beneficial to deeply understand the roles and mechanisms of AR in stretch-regulated muscle mass and strength; and reports firstly that myoblasts sense mechanical stimulus and transmit into intracellular AR via α7β1 integrin.

131 (PB119): Novel Androgen Receptor Antagonists with Improved Activity Against Common LBD Variants Associated with Therapeutic Resistance

131 (PB119): Novel Androgen Receptor Antagonists with Improved Activity Against Common LBD Variants Associated with Therapeutic Resistance

A Rationalized Approach to Design and Discover Novel Non-steroidal Derivatives through Computational Aid for the Treatment of Prostate Cancer.

Prostate cancer is one of the most prevalent cancers in men, leading to the second most common cause of death in men. Despite the availability of multiple treatments, the prevalence of prostate cancer remains high. Steroidal antagonists are associated with poor bioavailability and side effects, while non-steroidal antagonists show serious side effects, such as gynecomastia. Therefore, there is a need for a potential candidate for the treatment of prostate cancer with better bioavailability, good therapeutic effects, and minimal side effects. This current research work focused on identifying a novel non-steroidal androgen receptor antagonist through computational tools, such as docking and in silico ADMET analysis. Molecules were designed based on a literature survey, followed by molecular docking of all designed compounds and ADMET analysis of the hit compounds. A library of 600 non-steroidal derivatives (cis and trans) was designed, and molecular docking was performed in the active site of the androgen receptor (PDBID: 1Z95) using Auto- Dock Vina 1.5.6. Docking studies resulted in 15 potent hits, which were then subjected to ADME analysis using SwissADME. ADME analysis predicted three compounds (SK-79, SK-109, and SK-169) with the best ADME profile and better bioavailability. Toxicity studies using Protox-II were performed on the three best compounds (SK-79, SK-109, and SK-169), which predicted ideal toxicity for these lead compounds. This research work will provide ample opportunities to explore medicinal and computational research areas. It will facilitate the development of novel androgen receptor antagonists in future experimental studies.