Drug discovery for breast cancer and co-instantaneous cardiovascular disease: what is the future?

Docking-based classification models for exploratory toxicology studies on high-quality estrogenic experimental data

BACKGROUND

The ethical and practical limitation of animal testing has recently promoted computational methods for the fast screening of huge collections of chemicals.

RESULTS

The authors derived 24 reliable docking-based classification models able to predict the estrogenic potential of a large collection of chemicals provided by the US Environmental Protection Agency. Model performances were challenged by considering AUC, EF1% (EFmax = 7.1), -LR (at sensitivity = 0.75); +LR (at sensitivity = 0.25) and 37 reference compounds comprised within the training set. Moreover, external predictions were made successfully on ten representative known estrogenic chemicals and on a set consisting of >32,000 chemicals.

CONCLUSION

The authors demonstrate that structure-based methods, widely applied to drug discovery programs, can be fairly adapted to exploratory toxicology studies.

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.

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.