Isopropylidene Substitution Increases Activity and Selectivity of Biphenylmethylene 4-Pyridine Type CYP17 Inhibitors

Non-steroidal CYP17A1 Inhibitors: Discovery and Assessment

CYP17A1 is an enzyme that plays a major role in steroidogenesis and is critically involved in the biosynthesis of steroid hormones. Therefore, it remains an attractive target in several serious hormone-dependent cancer diseases, such as prostate cancer and breast cancer. The medicinal chemistry community has been committed to the discovery and development of CYP17A1 inhibitors for many years, particularly for the treatment of castration-resistant prostate cancer. The current Perspective reflects upon the discovery and evaluation of non-steroidal CYP17A1 inhibitors from a medicinal chemistry angle. Emphasis is placed on the structural aspects of the target, key learnings from the presented chemotypes, and design guidelines for future inhibitors.

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.

Copper-Catalyzed Enantioconvergent Radical Suzuki-Miyaura C(sp3)-C(sp2) Cross-Coupling

A copper-catalyzed enantioconvergent Suzuki-Miyaura C(sp³)-C(sp²) cross-coupling of various racemic alkyl halides with organoboronate esters has been established in high enantioselectivity. Critical to the success is the use of a chiral cinchona alkaloid-derived N,N,P-ligand for not only enhancing the reducing capability of copper catalyst to favor a stereoablative radical pathway over a stereospecific S_N2-type process but also providing an ideal chiral environment to achieve the challenging enantiocontrol over the highly reactive radical species. The reaction has a broad scope with respect to both coupling partners, covering aryl- and heteroarylboronate esters, as well as benzyl-, heterobenzyl-, and propargyl bromides and chlorides with good functional group compatibility. Thus, it provides expedient access toward a range of useful enantioenriched skeletons featuring chiral tertiary benzylic stereocenters.

Prospective computational design and in vitro bio-analytical tests of new chemical entities as potential selective CYP17A1 lyase inhibitors

The development and advancement of prostate cancer (PCa) into stage 4, where it metastasize, is a major problem mostly in elder males. The growth of PCa cells is stirred up by androgens and androgen receptor (AR). Therefore, therapeutic strategies such as blocking androgens synthesis and inhibiting AR binding have been explored in recent years. However, recently approved drugs (or in clinical phase) failed in improving the expected survival rates for this metastatic-castration resistant prostate cancer (mCRPC) patients. The selective CYP17A1 inhibition of 17,20-lyase route has emerged as a novel strategy. Such inhibition blocks the production of androgens everywhere they are found in the body. In this work, a three dimensional-quantitative structure activity relationship (3D-QSAR) pharmacophore model is developed on a diverse set of non-steroidal inhibitors of CYP17A1 enzyme. Highly active compounds are selected to define a six-point pharmacophore hypothesis with a unique geometrical arrangement fitting the following description: two hydrogen bond acceptors (A), two hydrogen bond donors (D) and two aromatic rings (R). The QSAR model showed adequate predictive statistics. The 3D-QSAR model is further used for database virtual screening of potential inhibitory hit structures. Density functional theory (DFT) optimization provides the electronic properties explaining the reactivity of the hits. Docking simulations discovers hydrogen bonding and hydrophobic interactions as responsible for the binding affinities of hits to the CYP17A1 Protein Data Bank structure. 13 hits from the database search (including five derivatives) are then synthesized in the laboratory as different scaffolds. Ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in vitro experiments reveals three new chemical entities (NCEs) with half maximal inhibitory concentration (IC₅₀) values against the lyase route at mid-micromolar range with favorable selectivity to the lyase over the hydroxylase route (one of them with null hydroxylase inhibition). Thus, prospective computational design has enabled the design of potential lead lyase-selective inhibitors for further studies.

Rh-Catalyzed Highly Enantioselective Synthesis of Aliphatic Sulfonyl Fluorides

Rh-catalyzed, highly enantioselective (up to 99.8% ee) synthesis of aliphatic sulfonyl fluorides was accomplished. This protocol provides a portal to a class of novel 2-aryl substituted chiral sulfonyl fluorides, which are otherwise extremely difficult to access. This asymmetric synthesis has the feature of mild conditions, excellent functional group compatibility, and wide substrate scope (51 examples) generating a wide array of structurally unique chiral β-arylated sulfonyl fluorides for sulfur(VI) fluoride exchange (SuFEx) click reaction and drug discovery.

Human cytochrome P450 enzymes 5-51 as targets of drugs and natural and environmental compounds: mechanisms, induction, and inhibition - toxic effects and benefits

Cytochrome P450 (P450, CYP) enzymes have long been of interest due to their roles in the metabolism of drugs, pesticides, pro-carcinogens, and other xenobiotic chemicals. They have also been of interest due to their very critical roles in the biosynthesis and metabolism of steroids, vitamins, and certain eicosanoids. This review covers the 22 (of the total of 57) human P450s in Families 5-51 and their substrate selectivity. Furthermore, included is information and references regarding inducibility, inhibition, and (in some cases) stimulation by chemicals. We update and discuss important aspects of each of these 22 P450s and questions that remain open.

Stereospecific Decarboxylative Benzylation of Enolates: Development and Mechanistic Insight

A palladium-catalyzed decarboxylative coupling of enol carbonates with diarylmethyl electrophiles that are derived from secondary benzylic alcohols has been developed. This method allows the generation of a variety of β-diaryl ketones through an efficient and highly stereospecific coupling. In addition, detailed mechanistic insight into the coupling suggests that the reaction is a rare example of an intramolecular decarboxylative coupling that proceeds without crossover between reactants.

Two stereocentered HKR of anti-β,β′-diphenylpropanoxirane and anti-3-phenylethyloxiranes catalysed by Co(iii)(salen)-OAc complex: enantioselective synthesis of (+)-sertraline and (+)-naproxen

Two stereocentered HKR of anti-β,β′-diphenylmethyloxirane and anti-3-phenylethyloxiranes gives enantiopure anti-1,2-diols and oxiranes. This method is utilised for the synthesis of (+)-sertraline and (+)-naproxen.

Multi-Component One-Pot Reaction of Aromatic Carbonyl Compounds, Tosylhydrazide, and Arylboronic Acids

In this paper, we developed a new method using 4-bromoacetophenone as the starting material, with tosylhydrazide and two arylboronic acids using Barluenga and Suzuki couplings in a four-component one-pot reaction to afford the target product 4-benzyl-1,1′-biphenyls. This system that we have developed enables the use of easily accessible starting materials and can be employed on a wide variety of substrates with good functional group tolerance. In particular, this protocol can be applied to the synthesis of 4-(1-([1,1′-biphenyl]-4-yl)ethyl)pyridine derivatives, a class of potential analogs of CPY17 inhibitors of prostate cancer.

Discovery of novel 1,2,3,4-tetrahydrobenzo[4, 5]thieno[2, 3-c]pyridine derivatives as potent and selective CYP17 inhibitors

The inhibition of CYP17 to block androgen biosynthesis is a well validated strategy for the treatment of prostate cancer. Herein we reported the design, synthesis and structure-activity relationship (SAR) study for a series of novel 1,2,3,4- tetrahydrobenzo[4,5]thieno[2,3-c]pyridine derivatives. Some analogs demonstrated a potent inhibition to both rat and human CYP17 protein and reduced testosterone production in human H295R cell line. Some analogs also showed high selectivity against other CYP enzymes such as 3A4, 1A2, 2C9, 2C19 and 2D6, which may limit side effects due to drug-drug interactions. Among these analogs, the most potent compound 9c showed 1.5 fold more potent against rat and human CYP17 protein than that of abiraterone (IC₅₀ = 16 nM and 20 nM vs. 25 nM and 36 nM respectively). In NCI-H295R cells, the inhibitory effect of compound 9c on testosterone production (52± 2%) was also more potent than that of abiraterone (74± 15%) at the concentration of 1 μM. Further, it was shown that 9c reduced plasma testosterone level in a dose-dependent manner in Sprague-Dawley rats. Thus, analog 9c maybe a potential agent used for the treatment of prostate cancer.

Aptamer-based Field-Effect Biosensor for Tenofovir Detection

During medical treatment it is critical to maintain the circulatory concentration of drugs within their therapeutic range. A novel biosensor is presented in this work to address the lack of a reliable point-of-care drug monitoring system in the market. The biosensor incorporates high selectivity and sensitivity by integrating aptamers as the recognition element and field-effect transistors as the signal transducer. The drug tenofovir was used as a model small molecule. The biointerface of the sensor is a binary self-assembled monolayer of specific thiolated aptamer and 6-mercapto-1-hexanol (MCH), whose ratio was optimized by electrochemical impedance spectroscopy measurements to enhance the sensitivity towards the specific target. Surface plasmon resonance, performed under different buffer conditions, shows optimum specific and little non-specific binding in phosphate buffered saline. The dose-response behavior of the field-effect biosensor presents a linear range between 1 nM and 100 nM of tenofovir and a limit of detection of 1.2 nM. Two non-specific drugs and one non-specific aptamer, tested as stringent control candidates, caused negligible responses. The applications were successfully extended to the detection of the drug in human serum. As demonstrated by impedance measurements, the aptamer-based sensors can be used for real-time drug monitoring.

Enzymatic and Nonenzymatic Electrochemical Interaction of Abiraterone (Antiprostate Cancer Drug) with Multiwalled Carbon Nanotube Bioelectrodes

Unexplored electrochemical behavior of abiraterone, a recent and widely used prostate cancer drug, in interaction with cytochrome P450 3A4 (CYP3A4) enzyme and multiwalled carbon nanotubes (MWCNTs) is investigated in this work. The results reported in this work are significant for personalized medicine and point-of-care chemical treatment, especially to improve the life expectancy and quality of life of patients with prostate-cancer. To this purpose, enzymatic and nonenzymatic electrochemical biosensors were developed and characterized with different concentrations of abiraterone. Nonenzymatic biosensors were functionalized with MWCNTs as a catalyst for signal enhancement, while enzymatic biosensors have been obtained with CYP3A4 protein immobilized on MWCNTs as recognition biomolecule. Enzymatic electrochemical experiments demonstrated an inhibition effect on the CYP3A4, clearly observed as a diminished electrocatalytic activity of the enzyme. Electrochemical responses of nonenzymatic biosensors clearly demonstrated the direct electroactivity of abiraterone when reacting with MWCNT as well as an electrode-fouling effect.

Therapeutic compounds for Cushing's syndrome: a patent review (2012-2016)

INTRODUCTION

Endogenous Cushing's syndrome (CS) is a set of disorders caused by chronic exposure to excess glucocorticoids induced by neuroendocrine tumors in pituitary, adrenals, and infrequently other sites (ectopic ACTH syndrome). Due to various comorbidities, CS patients exhibit higher risks of cardiovascular diseases and thus increased mortality. Pharmaceutical therapy is an important constituent of treatment regimen. Areas covered: Patents published since 2012 are reviewed, which claim therapeutic compounds interfering with ACTH secretion and down-stream signal transduction, inhibiting cortisol biosynthesis and antagonizing glucocorticoid receptors. Advances focus on a) new analogues with improved efficacy and PK properties or less off-target toxicity; b) existing drugs (candidates) being repurposed to treat CS; and c) novel strategies such as selective inhibition of CYP11B1. Expert opinion: New compounds against established targets need to be developed because current drugs lack selectivity leading to off-target toxicity. Selective inhibition of CYP11B1 is a novel alternative strategy and is potentially versatile in controlling all types of hypercortisolism. Selective multi-targeting enzymes in steroidogenesis network is promising due to potential synergistic effects. However, doses toward each targets are not feasible to adjust because the corresponding intrinsic potencies are rigid. Targeting PRKACA mutations is promising in treating CS caused by adrenal adenomas.

Promising Tools in Prostate Cancer Research: Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors

Cytochrome P450 17A1 (CYP17A1) is an important target in the treatment of prostate cancer because it produces androgens required for tumour growth. The FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects. Using non-steroidal scaffolds is expected to enable the design of compounds that interact more selectively with CYP17A1. Therefore, we combined a structure-based virtual screening approach with density functional theory (DFT) calculations to suggest non-steroidal compounds selective for CYP17A1. In vitro assays demonstrated that two such compounds selectively inhibited CYP17A1 17α-hydroxylase and 17,20-lyase activities with IC50 values in the nanomolar range, without affinity for the major drug-metabolizing CYP2D6 and CYP3A4 enzymes and CYP21A2, with the latter result confirmed in human H295R cells.

Identification of 4-(4-nitro-2-phenethoxyphenyl)pyridine as a promising new lead for discovering inhibitors of both human and rat 11β-Hydroxylase

The inhibition of 11β-hydroxylase is a promising strategy for the treatment of Cushing's syndrome, in particular for the recurrent and subclinical cases. To achieve proof of concept in rats, efforts were paid to identify novel lead compounds inhibiting both human and rat CYP11B1. Modifications on a potent promiscuous inhibitor of hCYP11B1, hCYP11B2 and hCYP19 (compound IV) that exhibited moderate rCYP11B1 inhibition led to compound 8 as a new promising lead compound. Significant improvements compared to starting point IV were achieved regarding inhibitory potency against both human and rat CYP11B1 (IC50 values of 2 and 163 nM, respectively) as well as selectivity over hCYP19 (IC50 = 1900 nM). Accordingly, compound 8 was around 7- and 28-fold more potent than metyrapone regarding the inhibition of human and rat CYP11B1 and exhibited a comparable selectivity over hCYP11B2 (SF of 3.5 vs 4.9). With further optimizations on this new lead compound 8, drug candidates with satisfying profiles are expected to be discovered.

Novel pyridyl substituted 4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolines as potent and selective aldosterone synthase inhibitors with improved in vitro metabolic stability

CYP11B2 inhibition is a promising treatment for diseases caused by excessive aldosterone. To improve the metabolic stability in human liver miscrosomes of previously reported CYP11B2 inhibitors, modifications were performed via a combination of ligand- and structure-based drug design approaches, leading to pyridyl 4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolones. Compound 26 not only exhibited a much longer half-life (t1/2 ≫ 120 min), but also sustained inhibitory potency (IC50 = 4.2 nM) and selectivity over CYP11B1 (SF = 422), CYP17, CYP19, and a panel of hepatic CYP enzymes.

Organocatalytic asymmetric reaction of indol-2-yl carbinols with enamides: synthesis of chiral 2-indole-substituted 1,1-diarylalkanes

The chiral phosphoramide-catalyzed asymmetric reaction of indol-2-yl carbinols with enamides is presented.

Stereospecific nickel-catalyzed cross-coupling reactions of alkyl Grignard reagents and identification of selective anti-breast-cancer agents

Alkyl Grignard reagents that contain β-hydrogen atoms were used in a stereospecific nickel-catalyzed cross-coupling reaction to form C(sp(3))-C(sp(3)) bonds. Aryl Grignard reagents were also utilized to synthesize 1,1-diarylalkanes. Several compounds synthesized by this method exhibited selective inhibition of proliferation of MCF-7 breast cancer cells.

One pot and selective intermolecular aryl- and heteroaryl-trifluoromethylation of alkenes by photoredox catalysis

A general and efficient photoredox-catalyzed intermolecular aryl- and heteroaryltrifluoromethylation of styrenes with Umemoto's reagent has been developed.

Synthetic methodologies of achiral diarylmethanols, diaryl and triarylmethanes (TRAMs) and medicinal properties of diaryl and triarylmethanes-an overview

This review covers the synthesis of achiral diarylmethanols, diaryl and triarylmethanes and the bioactivities of diaryl and triarylmethanes during 1995 to 2013.

CYP17 inhibitors--abiraterone, C17,20-lyase inhibitors and multi-targeting agents

As the first in class steroid 17α-hydroxylase/C17,20-lyase (CYP17) inhibitor, abiraterone acetate (of which the active metabolite is abiraterone) has been shown to improve overall survival in patients with castration-resistant prostate cancer (CRPC)--in those who are chemotherapy-naive and those previously treated with docetaxel. Furthermore, the clinical success of abiraterone demonstrated that CRPC, which has previously been regarded as an androgen-independent disease, is still driven, at least in part, by androgens. More importantly, abiraterone is a 'promiscuous' drug that interacts with a number of targets, which dictate its clinical benefits and adverse effects profile. Besides CYP17 inhibition, abiraterone acts as an antagonist to the androgen receptor and inhibits 3β-hydroxysteroid dehydrogenase--two effects that potentially contribute to its antitumour effects. However, the inhibition of the 17α-hydroxylase activity of CYP17, CYP11B1 and a panel of hepatic CYP enzymes leads to adverse effects and toxicities that include secondary mineralocorticoid excess. Abiraterone is also associated with increased incidence of cardiac disorders. Under such circumstances, development of new CYP17 inhibitors as an additional line of defence is urgently needed. To achieve enhanced clinical benefits, new strategies are being explored that include selective inhibition of the C17,20-lyase activity of CYP17 and multi-targeting strategies that affect androgen synthesis and signalling at different points. Some of these strategies-including the drugs orteronel, VT-464 and galeterone--are supported by preclinical data and are being explored in the clinic.

Pd(0)-catalyzed 1,1-diarylation of ethylene and allylic carbonates

An efficient protocol for the one-step synthesis of biologically relevant 1,1-diarylalkanes has been described. This reaction introduces two different aryl groups across the terminal end of simple feedstock alkenes such as ethylene and allylic carbonates. The propensity to generate π-benzylpalladium intermediates dictates the exclusive 1,1-regioselectivity observed in the product.

Highly potent and selective nonsteroidal dual inhibitors of CYP17/CYP11B2 for the treatment of prostate cancer to reduce risks of cardiovascular diseases

Dual CYP17/CYP11B2 inhibitors are proposed as a novel strategy for the treatment of prostate cancer to reduce risks of cardiovascular diseases. Via a combination of ligand- and structure-based approaches, a series of dual inhibitors were designed leading to the 2-(3-pyridyl)naphthalenes 10 and 11 with strong inhibition of both enzymes (IC50 values around 20 nM) and excellent selectivities over CYP11B1, CYP19, and CYP3A4. These compounds are considered as promising candidates for further in vivo evaluation.

Recent progress in pharmaceutical therapies for castration-resistant prostate cancer

Since 2010, six drugs have been approved for the treatment of castration-resistant prostate cancer, i.e., CYP17 inhibitor Abiraterone, androgen receptor antagonist Enzalutamide, cytotoxic agent Cabazitaxel, vaccine Sipuleucel-T, antibody Denosumab against receptor activator of nuclear factor kappa B ligand and radiopharmaceutical Alpharadin. All these drugs demonstrate improvement on overall survival, expect for Denosumab, which increases the bone mineral density of patients under androgen deprivation therapy and prolongs bone-metastasis-free survival. Besides further CYP17 inhibitors (Orteronel, Galeterone, VT-464 and CFG920), androgen receptor antagonists (ARN-509, ODM-201, AZD-3514 and EZN-4176) and vaccine Prostvac, more drug candidates with various mechanisms or new indications of launched drugs are currently under evaluation in different stages of clinical trials, including various kinase inhibitors and platinum complexes. Some novel strategies have also been proposed aimed at further potentiation of antitumor effects or reduction of side effects and complications related to treatments. Under these flourishing circumstances, more investigations should be performed on the optimal combination or the sequence of treatments needed to delay or reverse possible resistance and thus maximize the clinical benefits for the patients.