Development and clinical utility of abiraterone acetate as an androgen synthesis inhibitor

Exploration and biological evaluation of 20-vinyl pregnenes: A step forward toward selective modulators of the estrogen receptor α signaling for breast cancer treatment

A series of D-ring modified steroids bearing a vinyl ketone pendant were synthesized and evaluated for antiproliferative activity against breast cancer cell line and cytochromes P450. The lead compound, 21-vinyl 20-keto-pregnene (2f) (IC50 = 2.4 µM), was shown to be a promising candidate for future anticancer drug design, particularly against estrogen receptor α (ERα)-positive breast cancer. The lead compound was found to have a significant effect on the signaling pathways in parental and 4-hydroxytamoxifen-resistant cells. Compound 2f modulated the ERK, cyclin D1, and CDK4 pathways and blocked the expression of ERα, the main driver of breast cancer growth. Compound 2f significantly reduced 17β-estradiol-induced progesterone receptor expression. Accumulation of cleaved poly(ADP-ribose) polymerase in cells treated with compound 2f indicated induction of apoptosis. The selectivity analysis showed that lead compound 2f produces no significant effects on cytochromes P450, CYP19A1, CYP21A2, and CYP7B1.

Abiraterone in Classic Congenital Adrenal Hyperplasia: Results of Medical Therapy Before Adrenalectomy

We present the case of a 20-year-old woman with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency, with uncontrolled hyperandrogenemia despite supraphysiological glucocorticoid therapy. We used abiraterone acetate, an inhibitor of the 17-hydroxylase/17,20-lyase enzyme, to suppress adrenal androgen synthesis and allow physiological glucocorticoid and mineralocorticoid therapy, as a proof-of-concept, before proceeding to bilateral adrenalectomy. We report the patient's clinical course, the changes in adrenal steroids, and the immunohistochemistry of the adrenals.

Approaches to Prevent and Manage Cardiovascular Disease in Patients Receiving Therapy for Prostate Cancer

PURPOSE OF REVIEW

Prostate cancer (PCa) is amongst the most common cancers in men worldwide. Cardiovascular (CV) risk factors and CV disease (CVD) are common comorbidities in this patient population, posing a challenge for PCa-directed therapies which can cause or worsen CVRFs and CVDs. Herein, we summarize the approaches to prevent and manage CVD in patients with PCa receiving therapy.

RECENT FINDINGS

While patients with locally advanced and metastatic PCa benefit from hormonal therapy, these treatments can potentially cause CV toxicity. Androgen receptor targeting therapies, such as androgen deprivation therapy (ADT), can induce metabolic changes and directly impact cardiovascular function, thereby reducing cardiorespiratory fitness and increasing CV mortality. Moreover, more than half of the PCa patients have poorly controlled CV risk factors at baseline. Hence, there is an urgent need to address gaps in preventing and managing CVD in PCa patients. Screening and optimizing CV risk factors and CVD in patients undergoing ADT are essential to reduce CV mortality, the leading non-cancer cause of death in PCa survivors. The risk of CV morbidity and mortality can be further mitigated by considering the patient's cardiovascular risk profile when deciding the choice and duration of ADT. A multidisciplinary team-based approach is crucial to achieve the best outcomes for PCa patients undergoing therapy.

Pseurotin A Validation as a Metastatic Castration-Resistant Prostate Cancer Recurrence-Suppressing Lead via PCSK9-LDLR Axis Modulation

Metastatic castration-resistant prostate cancer (mCRPC) cells can de novo biosynthesize their own cholesterol and overexpress proprotein convertase subtilisin/kexin type 9 (PCSK9). PCSK9 proved to contribute to mCRPC cell motility since PCSK9 knockdown (KD) in mCRPC CWR-R1ca cells led to notable reductions in cell migration and colony formation. Human tissue microarray results proved a higher immunohistoscore in patients ≥ 65 years old, and PCSK9 proved to be expressed higher at an early Gleason score of ≤7. The fermentation product pseurotin A (PS) suppressed PCSK9 expression, protein-protein interactions with LDLR, and breast and prostate cancer recurrences. PS suppressed migration and colony formation of the CWR-R1ca cells. The progression and metastasis of the CWR-R1ca-Luc cells subcutaneously (sc) xenografted into male nude mice fed a high-fat diet (HFD, 11% fat content) showed nearly 2-fold tumor volume, metastasis, serum cholesterol, low-density lipoprotein cholesterol (LDL-C), prostate-specific antigen (PSA), and PCSK9 levels versus mice fed a regular chow diet. Daily oral PS 10 mg/kg treatments prevented the locoregional and distant tumor recurrence of CWR-R1ca-Luc engrafted into nude mice after primary tumor surgical excision. PS-treated mice showed a significant reduction in serum cholesterol, LDL-C, PCSK9, and PSA levels. These results comprehensively validate PS as an mCRPC recurrence-suppressive lead by modulating the PCSK9-LDLR axis.

Modulating the Activity of Androgen Receptor for Treating Breast Cancer

The androgen receptor (AR) is a steroid hormone receptor widely detected in breast cancer. Evidence suggests that the AR might be a tumor suppressor in estrogen receptor alpha-positive (ERα+ve) breast cancer but a tumor promoter in estrogen receptor alpha-negative (ERα-ve) breast cancer. Modulating AR activity could be a potential strategy for treating breast cancer. For ERα+ve breast cancer, activation of the AR had been demonstrated to suppress the disease. In contrast, for ERα-ve breast cancer, blocking the AR could confer better prognosis to patients. These studies support the feasibility of utilizing AR modulators as anti-cancer drugs for different subtypes of breast cancer patients. Nevertheless, several issues still need to be addressed, such as the lack of standardization in the determination of AR positivity and the presence of AR splice variants. In future, the inclusion of the AR status in the breast cancer report at the time of diagnosis might help improve disease classification and treatment decision, thereby providing additional treatment strategies for breast cancer.

The Discovery of BMS-737 as a Potent, CYP17 Lyase-Selective Inhibitor for the Treatment of Castration-Resistant Prostate Cancer

We report herein, the discovery of BMS-737 (compound 33) as a potent, non-steroidal, reversible small molecule inhibitor demonstrating 11-fold selectivity for CYP17 lyase over CYP17 hydroxylase, as well as a clean xenobiotic CYP profile for the treatment of castration-resistant prostate cancer (CRPC). Extensive SAR studies on the initial lead 1 at three different regions of the molecule resulted in the identification of BMS-737, which demonstrated a robust 83% lowering of testosterone without any significant perturbation of the mineralocorticoid and glucocorticoid levels in cynomologous monkeys in a 1-day PK/PD study.

Targeting dual-specificity tyrosine phosphorylation-regulated kinase 2 with a highly selective inhibitor for the treatment of prostate cancer

Prostate cancer (PCa) is one of the most prevalent cancers in men worldwide, and hormonal therapy plays a key role in the treatment of PCa. However, the drug resistance of hormonal therapy makes it urgent and necessary to identify novel targets for PCa treatment. Herein, dual-specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2) is found and confirmed to be highly expressed in the PCa tissues and cells, and knock-down of DYRK2 remarkably reduces PCa burden in vitro and in vivo. On the base of DYRK2 acting as a promising target, we further discover a highly selective DYRK2 inhibitor YK-2-69, which specifically interacts with Lys-231 and Lys-234 in the co-crystal structure. Especially, YK-2-69 exhibits more potent anti-PCa efficacy than the first-line drug enzalutamide in vivo. Meanwhile, YK-2-69 displays favorable safety properties with a maximal tolerable dose of more than 10,000 mg/kg and pharmacokinetic profiles with 56% bioavailability. In summary, we identify DYRK2 as a potential drug target and verify its critical roles in PCa. Meanwhile, we discover a highly selective DYRK2 inhibitor with favorable druggability for the treatment of PCa.

The kinase DYRK2 is a known oncogene but its role in prostate cancer is unexplored. Here, the authors identify DYRK2 as a target for prostate cancer with a role in invasion and they discover a specific DYRK2 inhibitor that has good pharmacokinetics and efficacy in vivo.

P2Y1 agonist HIC in combination with androgen receptor inhibitor abiraterone acetate impairs cell growth of prostate cancer

P2Y receptors belong to the large superfamily of G-protein-coupled receptors and play a crucial role in cell death and survival. P2Y1 receptor has been identified as a marker for prostate cancer (PCa). A previously unveiled selective P2Y1 receptor agonist, the indoline-derived HIC (1-(1-((2-hydroxy-5-nitrophenyl)(4-hydroxyphenyl)methyl)indoline-4-carbonitrile), induces a series of molecular and biological responses in PCa cells PC3 and DU145, but minimal toxicity to normal cells. Here, we evaluated the combinatorial effect of HIC with abiraterone acetate (AA) targeted on androgen receptor (AR) on the inhibition of PCa cells. Here, the presence of HIC and AA significantly inhibited cell proliferation of PC3 and DU145 cells with time-dependent manner as a synerfistic combination. Moreover, it was also shown that the anticancer and antimetastasis effects of the combinratorial drugs were noticed through a decrease in colony-forming ability, cell migration, and cell invasion. In addition, the HIC + AA induced apoptotic population of PCa cells as well as cell cycle arrest in G1 progression phase. In summary, these studies show that the combination of P2Y1 receptor agonist, HIC and AR inhibitor, AA, effectively improved the antitumor activity of each drug. Thus, the combinatorial model of HIC and AA should be a novel and promising therapeutic strategy for treating prostate cancer.

Highlights on Steroidal Arylidene Derivatives as a Source of Pharmacologically Active Compounds: A Review

Steroids constitute a unique class of chemical compounds, playing an important role in physiopathological processes, and have high pharmacological interest. Additionally, steroids have been associated with a relatively low toxicity and high bioavailability. Nowadays, multiple steroidal derivatives are clinically available for the treatment of numerous diseases. Moreover, different structural modifications on their skeleton have been explored, aiming to develop compounds with new and improved pharmacological properties. Thus, steroidal arylidene derivatives emerged as a relevant example of these modifications. This family of compounds has been mainly described as 17β-hydroxysteroid dehydrogenase type 1 and aromatase inhibitors, as well as neuroprotective and anticancer agents. Besides, due to their straightforward preparation and intrinsic chemical reactivity, steroidal arylidene derivatives are important synthetic intermediates for the preparation of other compounds, particularly bearing heterocyclic systems. In fact, starting from arylidenesteroids, it was possible to develop bioactive steroidal pyrazolines, pyrazoles, pyrimidines, pyridines, spiro-pyrrolidines, amongst others. Most of these products have also been studied as anti-inflammatory and anticancer agents, as well as 5α-reductase and aromatase inhibitors. This work aims to provide a comprehensive overview of steroidal arylidene derivatives described in the literature, highlighting their bioactivities and importance as synthetic intermediates for other pharmacologically active compounds.

Cancer stem cells and nanomedicine: new opportunities to combat multidrug resistance?

'Multidrug resistance' (MDR) is a difficult challenge for cancer treatment. The combined role of cytochrome P450 enzymes (CYPs) and active efflux transporters (AETs) in cancer cells appears relevant in inducing MDR. Chemotherapeutic drugs can be substrates of both CYPs and AETs and CYP inducers or inhibitors can produce the same effects on AETs. In addition, a small subpopulation of cancer stem-like cells (CSCs) appears to survive conventional chemotherapy, leading to recurrent disease. Natural products appear efficacious against CSCs; their combinational treatments with standard chemotherapy are promising for cancer eradication, in particular when supported by nanotechnologies.

Fe(iii)-Catalyzed synthesis of steroidal imidazoheterocycles as potent antiproliferative agents

An efficient and practical method has been developed for the synthesis of steroidal imidazoheterocycles via cost-effective and environmentally benign FeCl₃-catalyzed oxidative amination. A library of steroidal imidazo[1,2-a]pyridines was directly synthesized from readily available 2-aminopyridines and steroidal ketones in aerobic conditions. The synthesized compounds were screened for activity on human microsomal cytochrome P450s CYP7, CYP17 and CYP21. Antiproliferative activity of two lead compounds 3ia and 3la was additionally evaluated against the human MCF-7 (breast cancer), SKOV3 (ovarian cancer), and 22Rv1 (prostate cancer) cell lines. Steroidal imidazo[1,2-a]pyridine 3la which is a substrate molecule for CYP17A1 with IC₅₀ = 1.7 μM (MCF-7), 3.0 (SKOV3), and 6.0 μM (22Rv1) has proved to be more active than reference drug cisplatin.

Heterocyclic steroids: Efficient routes for annulation of pentacyclic steroidal pyrimidines

Steroids are components of cell membranes, signaling molecules and are a type of secondary metabolites as a result of their high impact of biological significance. The present review described the literature reports of pentacyclic steroidal pyrimidines as a type of heterocyclic steroids. The main sections included the synthesis of the investigated steroids fused at rings-A or B or D of steroid skeleton, synthesis of binary or linked-type pyrimidines, pyrimidine oxides, macromolecules and mono- or di- or tri-peptides linked-steroidal pyrimidines. Besides, the present research highlighted the biological significance of steroidal pyrimidines, in which the compounds revealed potent anticancer, antioxidant, antibacterial, and anti-Alzheimer agents. In addition, some hetero-steroids were screened for binding DNA assay and gene expression analysis. It was settled that the incorporation of pyrimidine scaffold into steroid basic skeleton is crucial for better biological results.

A novel pregnene analogs: synthesis, cytotoxicity on prostate cancer of PC-3 and LNCPa-AI cells and in silico molecular docking study

New pregnene analogs of N-hydroxamic acid 6, imino-propane hydrazides 7 and 8 as well as the aryl amides 9-11, oxadiazole, pyrazole and sulfinyl analogs 13-15, via the hydrazide analog 5 of methyl ((5-pregnen-3β,17β-diol-15α-yl)thio)propanoate (4) were synthesized. The in vitro cytotoxic activities of selected synthesized steroids against two human prostate cancer cell lines (PC-3, and LNCaP-AI) were evaluated by MTT assay. Compound 10 was the most active cytotoxic agent among these steroids against PC-3 and LNCaP-AI cell lines with inhibition of 96.2%, and 93.6% at concentration levels of 10.0 μM and 91.8%, and of 79.8% at concentration of 1.0 μM, respectively. Molecular docking study of 10 showed a hydrogen bonding with the amino acid Asn705 residue of the receptor 1E3G, together with hydrophobic interactions. Therefore, compound 10 can be considered as a promising anticancer agent due to its potent cytotoxic activity.

Design and synthesis of novel steroidal imidazoles as dual inhibitors of AR/CYP17 for the treatment of prostate cancer

Both AR and CYP17 are important targets for blocking androgen signaling, and it has been accepted that multifunctional drugs have a low risk of drug resistance in the treatment of cancer. Thus, herein a series of steroidal imidazoles were designed, synthesized and evaluated as dual AR/CYP17 ligands. Several compounds displayed good biological profiles in both enzymatic and cellular assays. SAR studies showed that introducing oximino at the C-3 position of steroidal scaffold is beneficial to the enhancement of AR antagonistic activity. Among these compounds, the most potent compound 13a exhibited the best AR inhibition (IC₅₀ = 0.5 μM) that was 27-fold increase compared with the hit compound 5 as well as comparable CYP17 inhibition (IC₅₀ = 11 μM). Additionally, 13a displayed promising anti-proliferative effects on LNCap cell lines with the IC₅₀ value of 23 μM which was superior to positive control Flutamide (IC₅₀ = 28 μM). Furthermore, the docking results of 13a revealed that the oxygen atom at the position of C-3 connected to the heme of CYP17, which may be helpful for its satisfactory dual-target inhibition. In summary, this study provides an efficient strategy for multi-targeting drug discovery in the treatment of prostate cancer.

Second-Generation Antiandrogens: From Discovery to Standard of Care in Castration Resistant Prostate Cancer

Prostate cancer is the most commonly diagnosed cancer affecting men in the United States. The prostate is a hormone-dependent gland in which androgen hormones testosterone and dihydrotestosterone bind to and activate the androgen receptor, initiating nuclear translocation of androgen receptor and a subsequent signaling cascade. Due to the androgen dependency of the prostate, androgen deprivation therapies have emerged as first line treatment for aggressive prostate cancer. Such therapies are effective until the point at which prostate cancer, through a variety of mechanisms including but not limited to generation of ligand-independent androgen receptor splice variants, or intratumoral androgen production, overcome hormone deprivation. These cancers are androgen ablation resistant, clinically termed castration resistant prostate cancer (CRPC) and remain incurable. First-generation antiandrogens established androgen receptor blockade as a therapeutic strategy, but these therapies do not completely block androgen receptor activity. Efficacy and potency have been improved by the development of second-generation antiandrogen therapies, which remain the standard of care for patients with CRPC. Four second-generation anti-androgens are currently approved by the Food and Drug Administration (FDA); abiraterone acetate, enzalutamide, and recently approved apalutamide and darolutamide. This review is intended to provide a thorough overview of FDA approved second-generation antiandrogen discovery, treatment application, strategies for combination therapy to overcome resistance, and an insight for the potential future approaches for therapeutic inhibition of androgen receptor.

Synthesis of D-Ring Annulated Pyridosteroids from β-Formyl Enamides and Their Biological Evaluations

Herein, we report the synthesis of a novel class of substituted androst[17,16- b]pyridines (pyridosteroids) from the reaction of β-formyl enamides with alkynes in high yields. The optimized reaction protocol was extended to acyclic and cyclic β-formyl enamides to afford nonsteroidal pyridines. Cell survival assay of all compounds were carried against prostate cancer PC-3 cells wherein 3-hydroxy-5-en-2',3'-dicarbethoxy-androst[17,16- b]pyridine showed the highest cytotoxic activity. Phase contrast microscopy and flow cytometry studies exhibited marked morphological features characteristic of apoptosis in 3-hydroxy-5-en-2',3'-dicarbethoxy-androst[17,16- b]pyridine and abiraterone treated PC-3 cells. The treatment of 3-hydroxy-5-en-2',3'-dicarbethoxy-androst[17,16- b]pyridine induces G₂/M phase cell cycle arrest in prostate cancer PC-3 cells. Enhancement of apoptotic inductions of PC-3 cells by 3-hydroxy-5-en-2',3'-dicarbethoxy-androst[17,16- b]pyridine and abiraterone through the activation of caspases-6, -7, and -8 pathways were supported by qRT-PCR. In silico study of the compound 3-hydroxy-5-en-2',3'-dicarbethoxy-androst[17,16- b]pyridine showed stable and promising interaction with the key caspase proteins. Our studies revealed that the pyridosteroid 3-hydroxy-5-en-2',3'-dicarbethoxy-androst[17,16- b]pyridine, bearing pyridine-2,3-dicarbethoxy pharmacophore, facilitated initiation of caspase-8 and activates downstream effectors caspase-6 and caspase-7 and thereby triggering apoptosis of PC-3 cancer cells.

Steroidal Pyrimidines and Dihydrotriazines as Novel Classes of Anticancer Agents against Hormone-Dependent Breast Cancer Cells

Most breast and prostate tumors are hormone-dependent, making it possible to use hormone therapy in patients with these tumors. The design of effective endocrine drugs that block the growth of tumors and have no severe side effects is a challenge. Thereupon, synthetic steroids are promising therapeutic drugs for the treatment of diseases such as hormone-dependent breast and prostate cancers. Here, we describe novel series of steroidal pyrimidines and dihydrotriazines with anticancer activities. A flexible approach to unknown pyrimidine and dihydrotriazine derivatives of steroids with selective control of the heterocyclization pattern is disclosed. A number of 18-nor-5α-androsta-2,13-diene[3,2-d]pyrimidine, androsta-2-ene[3,2-d]pyrimidine, Δ^{1, 3, 5(10)}-estratrieno[16,17-d]pyrimidine, and 17-chloro-16-dihydrotriazine steroids were synthesized by condensations of amidines with β-chlorovinyl aldehydes derived from natural hormones. The synthesized compounds were screened for cytotoxicity against breast cancer cells and showed IC₅₀ values of 7.4 μM and higher. Compounds were tested against prostate cancer cells and exhibited antiproliferative activity with IC₅₀ values of 9.4 μM and higher comparable to that of cisplatin. Lead compound 4a displayed selectivity in ERα-positive breast cancer cells. At 10 μM concentration, this heterosteroid inhibited 50% of the E2-mediated ERα activity and led to partial ERα down-regulation. The ERα reporter assay and immunoblotting were supported by the docking study, which showed the probable binding mode of compound 4a to the estrogen receptor pocket. Thus, heterosteroid 4a proved to be a selective ERα modulator with the highest antiproliferative activity against hormone-dependent breast cancer and can be considered as a candidate for further anticancer drug development. In total, the synthesized heterosteroids may be considered as new promising classes of active anticancer agents.

NHC-Cu(I)-Catalyzed Friedländer-Type Annulation of Fluorinated o-Aminophenones with Alkynes on Water: Competitive Base-Catalyzed Dibenzo[b,f][1,5]diazocine Formation

An efficient, easily scalable synthesis of 4-trifluoromethylquinolines and naphthydrines (as well as their difluoro- and perfluoro-analogues) as a result of tandem direct catalytic alkynylation/dehydrative condensation of o-aminofluoromethylketones (o-FMKs), for the first time catalyzed by NHC-copper(I) complexes on water, is reported. A wide range of terminal alkynes is tolerated under the reaction conditions, including β-lactam-, steroid-, and sugar-derived ones, leading to desired quinolines and naphthydrines with good yields. Further investigations proved that o-FMKs could be efficiently transformed into a rare class of heterocyclic compounds-dibenzo[b,f][1,5]diazocines-by a base-catalyzed condensation, also on water. The developed method was applied for gram-scale synthesis of a fluorinated analogue of G protein-coupled receptor antagonist (GPR91).

Synthesis and antiproliferative activity evaluation of steroidal imidazo[1,2-a]pyridines

An elegant approach to unknown steroidal imidazo[1,2-a]pyridine hybrids is disclosed. Unique derivatives of androstene and estrane series containing imidazo[1,2-a]pyridine motifs were prepared from 17-ethynyl steroids in good yields via copper-catalyzed cascade aminomethylation/cycloisomerization with imines. The synthesized compounds were screened for cytotoxicity against human breast (MCF-7, MDA-MB-231, HBL-100, MDA-MB-453) and prostate (LNCaP-LN3, PC-3, DU 145) cancer cell lines. The majority of tested compounds showed activities at μM level in breast cancer cells. The hormone-responsive breast cancer cells MCF-7 were more sensitive to novel compounds than ERα-negative cells; in particular, compounds 6a,b exhibited promising cytotoxicity against this cell line with the IC50 values in the range of 3-4μM. Furthermore, compound 4a showed remarkable effects as a selective ERα receptor modulator.

Hedgehog Proteins Consume Steroidal CYP17A1 Antagonists: Potential Therapeutic Significance in Advanced Prostate Cancer

Abiraterone, a potent inhibitor of the human enzyme CYP17A1 (cytochrome P450c17), provides a last line of defense against ectopic androgenesis in advanced prostate cancer. Herein we report an unprecedented off-target interaction between abiraterone and oncogenic hedgehog proteins. Our experiments indicate that abiraterone and its structural congener, galeterone, can replace cholesterol as a substrate in a specialized biosynthetic event of hedgehog proteins, known as cholesterolysis. The off-target reaction generates covalent hedgehog-drug conjugates. Cell-based reporter assays indicate that these conjugates activate hedgehog signaling when present in the low nanomolar range. Because hedgehog signaling is implicated in prostate cancer progression, and abiraterone is administered to treat advanced stages of the disease, this off-target interaction may have therapeutic significance.

Identification of Novel Steroidal Androgen Receptor Degrading Agents Inspired by Galeterone 3β-Imidazole Carbamate

Degradation of all forms of androgen receptors (ARs) is emerging as an advantageous therapeutic paradigm for the effective treatment of prostate cancer. In continuation of our program to identify and develop improved efficacious novel small-molecule agents designed to disrupt AR signaling through enhanced AR degradation, we have designed, synthesized, and evaluated novel C-3 modified analogues of our phase 3 clinical agent, galeterone (5). Concerns of potential in vivo stability of our recently discovered more efficacious galeterone 3β-imidazole carbamate (6) led to the design and synthesis of new steroidal compounds. Two of the 11 compounds, 3β-pyridyl ether (8) and 3β-imidazole (17) with antiproliferative GI50 values of 3.24 and 2.54 μM against CWR22Rv1 prostate cancer cell, are 2.75- and 3.5-fold superior to 5. In addition, compounds 8 and 17 possess improved (∼4-fold) AR-V7 degrading activities. Importantly, these two compounds are expected to be metabolically stable, making them suitable for further development as new therapeutics against all forms of prostate cancer.

Cellular androgen content influences enzalutamide agonism of F877L mutant androgen receptor

Prostate cancer is the most commonly diagnosed and second-most lethal cancer among men in the United States. The vast majority of prostate cancer deaths are due to castration-resistant prostate cancer (CRPC) - the lethal form of the disease that has progressed despite therapies that interfere with activation of androgen receptor (AR) signaling. One emergent resistance mechanism to medical castration is synthesis of intratumoral androgens that activate the AR. This insight led to the development of the AR antagonist enzalutamide. However, resistance to enzalutamide invariably develops, and disease progression is nearly universal. One mechanism of resistance to enzalutamide is an F877L mutation in the AR ligand-binding domain that can convert enzalutamide to an agonist of AR activity. However, mechanisms that contribute to the agonist switch had not been fully clarified, and there were no therapies to block AR F877L. Using cell line models of castration-resistant prostate cancer (CRPC), we determined that cellular androgen content influences enzalutamide agonism of mutant F877L AR. Further, enzalutamide treatment of AR F877L-expressing cell lines recapitulated the effects of androgen activation of F877L AR or wild-type AR. Because the BET bromodomain inhibitor JQ-1 was previously shown to block androgen activation of wild-type AR, we tested JQ-1 in AR F877L-expressing CRPC models. We determined that JQ-1 suppressed androgen or enzalutamide activation of mutant F877L AR and suppressed growth of mutant F877L AR CRPC tumors in vivo, demonstrating a new strategy to treat tumors harboring this mutation.

Inherited Variants in SULT1E1 and Response to Abiraterone Acetate by Men with Metastatic Castration Refractory Prostate Cancer

PURPOSE

Germline variations in genes involved in androgen biosynthesis and metabolic pathways may predict the response to abiraterone acetate in men with metastatic, castration refractory prostate cancer. The variations may serve as prognostic and predictive biomarkers to allow for more individualized therapy.

MATERIALS AND METHODS

We evaluated 832 single nucleotide polymorphisms from the OmniExpress genotyping platform (Illumina®) in the boundaries of 61 candidate genes reported to be involved in the androgen metabolic pathway. The purpose was to investigate them for an association with time to treatment failure in 68 white men with metastatic, castration refractory prostate cancer undergoing treatment with abiraterone acetate. Cox proportional hazard analysis was used with Gleason score, age, level of alkaline phosphatase and prostate specific antigen at treatment initiation as covariates. Each single nucleotide polymorphism was assessed using an allele carriage genetic model in which carriage of 1 or more minor alleles contributes to increased risk. Subset analyses were done to determine whether metastasis site, or prior treatment with ketoconazole or docetaxel would interact with the single nucleotide polymorphisms investigated.

RESULTS

Six single nucleotide polymorphisms in the estrogen sulfotransferase gene SULT1E1 were associated with time to treatment failure on abiraterone acetate therapy after false discovery rate (q value) correction for multiple testing while controlling for Gleason score, age, level of alkaline phosphatase and prostate specific antigen at treatment initiation (q <0.05).

CONCLUSIONS

Single nucleotide polymorphisms in SULT1E1 were significantly associated with time to treatment failure in men on abiraterone acetate therapy. The single nucleotide polymorphisms may serve as predictive markers for treatment with abiraterone acetate.

CYP17 inhibitors in prostate cancer: latest evidence and clinical potential

Since androgen signaling plays a pivotal role in the proliferation and metastasis of prostate cancer, androgen deprivation therapy (ADT) or castration therapy is considered the backbone of treatment for newly diagnosed metastatic prostate cancer. However, almost all men experience disease progression on ADT to a state known as metastatic castration-resistant prostate cancer (mCRPC), which continues to be driven by intratumoral androgen synthesis or androgen receptor signaling. Hence, the extragonadal ablation of androgen synthesis from pregnane precursors holds much promise. An inhibitor of cytochrome P450 17α-hydroxy/17,20-lyase (CYP17) enzymes, abiraterone acetate, has already been approved for men with mCRPC. Newer CYP17 inhibitors continue to be developed which are either more selective or have concomitant inhibitory actions on AR signaling. These include VT-464, orteronel, and galeterone. Herein, we focus on the molecular mechanism of action, efficacy, latest evidence, and clinical potential of CYP17 inhibitors in prostate cancer.

The evolving role of cytotoxic chemotherapy in the management of patients with metastatic prostate cancer

Prostate cancer (PC) is the most common cancer in men in the United States. Although outcomes are excellent for early-stage disease, survival for men with metastatic PC is limited. While older studies did not supported the use of chemotherapy in PC, the efficacy of taxane chemotherapy plus prednisone is now well established in men with metastatic castration resistant PC (CRPC). The results of CHAARTED trial have further expanded the use of chemotherapy to patients with metastatic hormone-sensitive disease. The clinical efficacy of taxanes over other chemotherapeutics may be a result of its ability to inhibit microtubule-dependent trafficking of proteins such as the androgen-receptor (AR). Ongoing research uses chemotherapy earlier in the disease course as well as explores the utility of combining cytotoxic chemotherapy with biologic agents.

Contemporary Systemic Therapy for Urologic Malignancies in Geriatric Patients

Current data on systemic therapy in geriatric populations with genitourinary malignancies are largely derived from retrospective analyses of prospectively conducted trials or retrospective reviews. Although extrapolation of these data to real-world patients should be cautious, patients aged 65 years or older with good functional status and minimal comorbidities seem to enjoy similar survival benefit from therapy as their younger counterparts. Chronologic age alone should generally not be used to guide management decisions. Comprehensive geriatric assessment tools and prospective studies in older adults integrating comprehensive geriatric assessment can shed light on the optimal management of urologic malignancies in this population.

New biaryl-chalcone derivatives of pregnenolone via Suzuki-Miyaura cross-coupling reaction. Synthesis, CYP17 hydroxylase inhibition activity, QSAR, and molecular docking study

A new class of steroids is being synthesized for its ability to prevent intratumoral androgen production by inhibiting the activity of CYP17 hydroxylase enzyme. The scheme involved the synthesis of chalcone derivative of pregnenolone 5 which was further modified to the corresponding biaryl-chalcone pregnenolone analogs 16-25 using Suzuki-Miyaura cross-coupling reaction. The synthesized compounds were tested for activity using human CYP17α hydroxylase expressed in Escherichia coli. Compounds 21 was the most active inhibitor in this series, with IC50 values of 0.61μM and selectivity profile of 88.7% inhibition of hydroxylase enzyme. Molecular docking study of 21 was performed and showed the hydrogen bonds and hydrophobic interaction with the amino acid residues of the active site of CYP17.

A new pregnenolone analogues as privileged scaffolds in inhibition of CYP17 hydroxylase enzyme. Synthesis and in silico molecular docking study

A new series of 17-(N-(arylimino)-5-pregnen-3β-ol derivatives 19-32 as well as carboxylate and acrylate analogues of pregnenolone 37-40 were synthesized and evaluated for their inhibitory activity against human CYP17 hydroxylase expressed in Escherichia coli. Compounds 32 and 37 were the most potent analogues in this series, showing inhibition activity with IC50 = 2.11 and 1.29 μM, respectively. However, the analogue 37 revealed a better selectivity profile (83.21% inhibition of hydroxylase), which is a leading candidate for further development. Molecular docking study of 37 showed binding with the amino acid residues of CYP17 through hydrogen bonds and hydrophobic interaction.

CYP17A1 inhibitors in castration-resistant prostate cancer

The majority of prostate cancer (PCa) cases are diagnosed as a localized disease. Definitive treatment, active surveillance or watchful waiting are employed as therapeutic paradigms. The current standard of care for the treatment of metastatic PCa is either medical or surgical castration. Once PCa progresses in spite of castrate androgen levels it is termed 'castration-resistant prostate cancer' (CRPC). Patients may even exhibit rising PSA levels with possible bone, lymph node or solid organ metastases. In 2010, the only agent approved for the treatment of CRPC was docetaxel, a chemotherapeutic agent. It is now known that cells from patients with CRPC express androgen receptors (AR) and remain continuously influenced by androgens. As such, treatments with novel hormonal agents that specifically target the biochemical conversion of cholesterol to testosterone have come to the forefront. The use of cytochrome P450c17 (CYP17A1) inhibitor underlies one of the most recent advances in the treatment of CRPC. Abiraterone acetate (AA) was the first CYP17A1 inhibitor approved in the United States. This review will discuss CRPC in general with a specific focus on AA and novel CYP17A1 inhibitors. AA clinical trials will be reviewed along with other novel adjunct treatments that may enhance the effectiveness of abiraterone therapy. Furthermore, the most recently identified CYP17A1 inhibitors Orteronel, Galeterone, VT-464, and CFG920 will also be explored.

Castration-resistant prostate cancer: latest evidence and therapeutic implications

Medical oncologists who treat men with castration-resistant prostate cancer (CRPC) have seen an abundance of new agents approved by the United States Food and Drug Administration in the last decade for a disease that was previously difficult to treat after becoming resistant to androgen-deprivation therapy. Advances in understanding of the mechanisms of castration-resistance and prostate cancer progression have highlighted several pathways and targets that appear promising to better treat CRPC. As the majority of CRPC appears to continue to rely on the androgen receptor for growth and progression, several of these agents directly or indirectly target the androgen receptor. A novel microtubule-targeted agent, cabazitaxel, has demonstrated an overall survival benefit following progression on docetaxel. Other agents target tumor immunogenicity and immune checkpoint pathways to attempt to harness the host immune system. The recently approved radiopharmaceutical, radium-223 dichloride, has demonstrated impressive results in patients with extensive bony metastases with minimal toxicity. Lastly, further understanding of the pathways underlying CRPC progression has led to late-phase clinical trials with the novel agents: custirsen, tasquinimod and cabozantinib. This article reviews the approved therapies for CRPC, the agents currently in late-phase clinical trials, and notable early-phase trials of novel therapies and their combinations, with particular attention to trials incorporating novel biomarkers and intermediate endpoints to better identify those men who may or may not benefit from specific therapies.

The changing landscape in metastatic castration-resistant prostate cancer

PURPOSE OF REVIEW

The treatment landscape in metastatic castration-resistant prostate cancer (mCRPC) has significantly changed in the recent years. We provide an updated summary of the new therapeutic agents in this disease and discuss open questions and future challenges.

RECENT FINDINGS

mCRPC is now known to frequently retain sensitivity to hormonal manipulation even after the development of castration resistance, and both the androgen synthesis inhibitor abiraterone and the androgen-receptor antagonist enzalutamide have recently shown to prolong survival in mCRPC patients after chemotherapy. Cabazitaxel, a new-generation antitubulin chemotherapeutic, and the radionuclide radium-223 chloride have also been shown to prolong survival. The biological agent cabozantinib, an orally bioavailable tyrosine kinase inhibitor with activity against Met and vascular endothelial growth factor receptor 2, demonstrated promising results in a phase II trial and is currently being assessed in two large randomized phase 3 controlled trials.

SUMMARY

This recent progress is unprecedented and has already translated to a significant increase in the available armamentarium of drugs for mCRPC. Nonetheless, there are still significant unresolved questions as to the proper sequencing of these novel drugs along the disease continuum. Moreover, the problem of drug resistance, either primary of acquired, continues to be a major therapeutic obstacle.

Steroidal 5α-reductase and 17α-hydroxylase/17,20-lyase (CYP17) inhibitors useful in the treatment of prostatic diseases

The role of steroidal inhibitors of androgen biosynthesis as potential weapons in the treatment of prostatic diseases, such as benign prostatic hyperplasia and prostatic cancer will be reviewed. Two enzymes have been targeted in the development of inhibitors that potentially could be useful in the management of such conditions. 5α-Reductase is primarily of interest in benign prostatic disease, though some role in the chemoprevention of prostatic carcinoma have been considered, whereas the 17α-hydroxylase/17,20-lyase (CYP17) enzyme is of interest in the treatment of malignant disease. An overview of the main achievements obtained during the past years will be presented, however special focus will be made on steroidal molecules that reached clinical trials or have been commercially launched. Relevant examples of such drugs are finasteride, dutasteride, abiraterone acetate and galeterone (TOK-001, formerly known as VN/124-1). This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Clinical Evaluation of Abiraterone in the Treatment of Metastatic Prostate Cancer

Treatment of castration-resistant prostate cancer remains an area of unmet medical need. Evidence suggests that this entity continues to be driven by androgens and androgen receptor (AR) signaling. Abiraterone acetate, a pregnenolone derivative, is an oral selective and irreversible inhibitor of the key steroidogenic enzyme CYP17. It possesses dual 17-α hydroxylase and C17,20-lyase blocking activity, the result of which is decreased gonadal and extra-gonadal androgen synthesis. Abiraterone was first approved by the US Food and Drug Administration (FDA) in 2011 following the demonstration of superior survival compared with placebo in the post-docetaxel population. Since that time, more evidence has been generated from preclinical studies and clinical trials which have considerably enhanced our understanding of this complex disease. In this paper, we review the development of abiraterone acetate, its pharmacological characteristics, and its effects on the androgen-AR signaling axis, along with the combined experience from clinical trials. We also discuss some of the ongoing trials using this agent, as well as potential mechanisms of abiraterone resistance, novel bio-marker development, and future directions using AR-directed therapies.

Systematic structure modifications of multitarget prostate cancer drug candidate galeterone to produce novel androgen receptor down-regulating agents as an approach to treatment of advanced prostate cancer

As part of our program to explore the influence of small structural modifications of our drug candidate 3β-(hydroxy)-17-(1H-benzimidazol-1-yl)androsta-5,16-diene (galeterone, 5) on the modulation of the androgen receptor (AR), we have prepared and evaluated a series of novel C-3, C-16, and C-17 analogues. Using structure activity analysis, we established that the benzimidazole moiety at C-17 is essential and optimal and also that hydrophilic and heteroaromatic groups at C-3 enhance both antiproliferative (AP) and AR degrading (ARD) activities. The most potent antiproliferative compounds were 3β-(1H-imidazole-1-carboxylate)-17-(1H-benzimidazol-1-yl)androsta-5,16-diene (47), 3-((EZ)-hydroximino)-17-(1H-benzimidazol-1-yl)androsta-4,16-diene (36), and 3β-(pyridine-4-carboxylate)-17-(1H-benzimidazol-1-yl)androsta-5,16-diene (43), with GI50 values of 0.87, 1.91, and 2.57 μM, respectively. Compared to 5, compound 47 was 4- and 8-fold more potent with respect to AP and ARD activities, respectively. Importantly, we also discovered that our compounds, including 5, 36, 43, and 47, could degrade both full-length and truncated ARs in CWR22rv1 human prostate cancer cells. With these activities, they have potential for development as new drugs for the treatment of all forms of prostate cancer.

Anticancer steroids: linking natural and semi-synthetic compounds

Steroids, a widespread class of natural organic compounds occurring in animals, plants and fungi, have shown great therapeutic value for a broad array of pathologies. The present overview is focused on the anticancer activity of steroids, which is very representative of a rich structural molecular diversity and ability to interact with various biological targets and pathways. This review encompasses the most relevant discoveries on steroid anticancer drugs and leads through the last decade and comprises 668 references.

Androgen receptor on the move: boarding the microtubule expressway to the nucleus

Recent studies have shown that the microtubule-stabilizing drug paclitaxel, which is commonly used for the treatment of prostate cancer, inhibits signaling from the androgen receptor by inhibiting its nuclear accumulation downstream of microtubule stabilization. This mechanism is independent of paclitaxel-induced mitotic arrest and could provide an alternative mechanism of drug action that can explain its clinical activity. In this review, we highlight the importance of signaling and trafficking pathways that depend on intact and dynamic microtubules, and, as such, they represent downstream targets of microtubule inhibitors. We showcase prostate cancer, which is driven by the activity of the androgen receptor, as recent reports have revealed a connection between the microtubule-dependent trafficking of the androgen receptor and the clinical efficacy of taxanes. Identification and further elucidation of microtubule-dependent tumor-specific pathways will help us better understand the molecular basis of clinical taxane resistance as well as to identify individual patients more likely to respond to treatment.

Abiraterone and other novel androgen-directed strategies for the treatment of prostate cancer: a new era of hormonal therapies is born

The number of life-prolonging therapies proven effective in the treatment of metastatic castrate-resistant prostate cancer (CRPC) has been limited until recently. In the past 2 years several such therapies have come to market. In 2010, the autologous immunotherapy sipuleucel-T and the next-generation taxane cabazitaxel were approved in this setting. However, abundant evidence has shown that CRPC growth continues to be driven through androgen-dependent signaling. Both of these drugs fail to take advantage of this targetable oncogenic pathway. Potent specific inhibitors of cytochrome P450-17 have been engineered with the aim of suppressing androgen synthesis beyond that seen with the luteinizing hormone-releasing hormone agonists/antagonists. Abiraterone acetate was developed by rational design based on a pregnenolone parent structure. Its approval by the US Food and Drug Administration (FDA) was granted in 2011 based on phase III data demonstrating an overall survival advantage compared with placebo. More recently, other drugs that act along the androgen signaling pathway, such as orteronel (TAK-700), galeterone (TOK-001), enzalutamide (MDV3100) and ARN-509, have shown promise in clinical trials. Some of these are expected to gain FDA approval in the near future. Here, we review abiraterone and other novel androgen-directed therapeutic strategies for the management of advanced prostate cancer.