Bicalutamide

Bicalutamide is an active non-steroidal androgen receptor antagonist with IC50 value of 160 nM.[1]
The androgen receptor (AR) is a type of nuclear receptor. It is activated by binding of either of dihydrotestosterone or the androgenic hormones testosterone. Then, it will translocate into the nucleus as DNA-binding transcription factor which regulates gene expression. Androgen is critical for the maintenance and development of the male sexual phenotype through related gene. The androgen receptor (AR) is also related to the core mechanism of castration-resistant prostate cancer.[1]
Bicalutamide inhibits growth in prostate cancer cells (VCaP cells) which overexpress androgen receptor by directly binding to AR then mediates androgen-mediated gene transcription with IC50 value of 160 nM. Bicalutamide directly binds to androgen receptor with Ki value of 12.5μM. In prostate cancer cells, bicalutamide impairs DNA binding and nuclear localization. Bicalutamide and MDV3100 significantly inhibited R1881-induced VP16-AR–mediated transcription in HepG2 cells with an IC50 value of 0.2 μM.[1] Bicalutamide has been an molecular template for designing selective androgen receptor antagonist used to the treatment of prostate cancer cells.[2] Bicalutamide also induces cell death by a different pathway which is independent of mitochondrial membrane potential changes and Bcl-2 action.[1]
Bicalutamide significantly inhibited AR then decrease the tumor growth in murine xenograft models, male immunodeficient mice which harbors LNCaP/AR-luc xenograft tumors.[1]
References:
[1].    Clegg NJ, Wongvipat J, Joseph JD, Tran C, Ouk S, Dilhas A, Chen Y, Grillot K, Bischoff ED, Cai L et al: ARN-509: a novel antiandrogen for prostate cancer treatment. Cancer Res 2012, 72(6):1494-1503.
[2].    Yin D, He Y, Perera MA, Hong SS, Marhefka C, Stourman N, Kirkovsky L, Miller DD, Dalton JT: Key structural features of nonsteroidal ligands for binding and activation of the androgen receptor. Mol Pharmacol 2003, 63(1):211-223.

Simultaneous quantitation of abiraterone, enzalutamide, N-desmethyl enzalutamide, and bicalutamide in human plasma by LC-MS/MS.[Pubmed:28219796]

J Pharm Biomed Anal. 2017 May 10;138:197-205.

Inhibiting the androgen receptor (AR) pathway is an important clinical strategy in metastatic prostate cancer. Novel agents including abiraterone acetate and enzalutamide have been shown to prolong life in men with metastatic, castration-resistant prostate cancer (mCRPC). To evaluate the pharmacokinetics of AR-targeted agents, we developed and validated an LC-MS/MS assay for the quantitation of enzalutamide, N-desmethyl enzalutamide, abiraterone and Bicalutamide in 0.05mL human plasma. After protein precipitation, chromatographic separation was achieved with a Phenomenex Synergi Polar-RP column and a linear gradient of 0.1% formic acid in methanol and water. Detection with an ABI 4000Q mass spectrometer utilized electrospray ionization in positive multiple reaction monitoring mode. The assay was linear over the ranges of 1-1000ng/mL for abiraterone and Bicalutamide and 100-30,000ng/mL for N-desmethyl enzalutamide and enzalutamide and proved to be accurate (92.8-107.7%) and precise (largest was 15.3% CV at LLOQ for Bicalutamide), and fulfilled FDA criteria for bioanalytical method validation. We demonstrated the suitability of this assay in plasma from patients who were administered enzalutamide 160mg, abiraterone 1000mg and Bicalutamide 50mg once a day as monotherapy or in combination. The LC-MS/MS assay that has been developed will be an essential tool that further defines the pharmacology of the combinations of androgen synthesis or AR-receptor targeted agents.

Planetary ball milling and supercritical fluid technology as a way to enhance dissolution of bicalutamide.[Pubmed:28363855]

Int J Pharm. 2017 Nov 30;533(2):470-479.

Dissolution of Bicalutamide processed with polyvinylpyrrolidone by either supercritical carbon dioxide or ball milling has been investigated. Various compositions as well as process parameters were used to obtain binary systems of the drug with the carrier. Thermal analysis and powder X-ray diffractometry confirmed amorphization of Bicalutamide mechanically activated by ball milling and the decrease in crystallinity of the supercritical carbon dioxide-treated drug. Both methods led to reduction of particles size what was confirmed by scanning electron microscopy and laser diffraction measurements. Moreover, the effect of micronisation was found to depend on the parameters of applied process. Fourier transform infrared spectroscopy revealed the appearance of intermolecular interactions between drug and carrier molecules that play an important role in the stabilization of amorphous form of the active compound. Changes in crystal structure combined with reduced size of particles of Bicalutamide dispersed within polymer matrix were found to improve dissolution of Bicalutamide by 4 to 10-fold in comparison to untreated drug. It is of particular importance as poor dissolution profiles are considered to be the major limitation in bioavailability of the drug.

Molecular Dynamics, Recrystallization Behavior, and Water Solubility of the Amorphous Anticancer Agent Bicalutamide and Its Polyvinylpyrrolidone Mixtures.[Pubmed:28231007]

Mol Pharm. 2017 Apr 3;14(4):1071-1081.

In this paper, we investigated the molecular mobility and physical stability of amorphous Bicalutamide, a poorly water-soluble drug widely used in prostate cancer treatment. Our broadband dielectric spectroscopy measurements and differential scanning calorimetry studies revealed that amorphous BIC is a moderately fragile material with a strong tendency to recrystallize from the amorphous state. However, mixing the drug with polymer polyvinylpyrrolidone results in a substantial improvement of physical stability attributed to the antiplasticizing effect governed by the polymer additive. Furthermore, IR study demonstrated the existence of specific interactions between the drug and excipient. We found out that preparation of Bicalutamide-polyvinylpyrrolidone mixture in a 2-1 weight ratio completely hinder material recrystallization. Moreover, we determined the time-scale of structural relaxation in the glassy state for investigated materials. Because molecular mobility is considered an important factor governing crystallization behavior, such information was used to approximate the long-term physical stability of an amorphous drug and drug-polymer systems upon their storage at room temperature. Moreover, we found that such systems have distinctly higher water solubility and dissolution rate in comparison to the pure amorphous form, indicating the genuine formulation potential of the proposed approach.

The preclinical development of bicalutamide: pharmacodynamics and mechanism of action.[Pubmed:8560673]

Urology. 1996 Jan;47(1A Suppl):13-25; discussion 29-32.

OBJECTIVES. To describe the preclinical development of Bicalutamide and clarify its pharmacodynamics and mechanisms of action. Bicalutamide was developed from a series of nonsteroidal compounds related to flutamide that showed a range of pharmacologic activity from full androgen agonist to pure antiandrogen, including progestational and antiprogestational properties. METHODS AND RESULTS. Bicalutamide is a pure antiandrogen that binds to rat, dog, and human prostate; the affinity compared with the natural ligand 5 alpha-dihydrotestosterone is low, but Bicalutamide has an affinity for the rat androgen receptor approximately four times higher than hydroxyflutamide, the active metabolite of flutamide. Bicalutamide also binds to androgen receptors found in the LNCaP human prostate tumor and the Shionogi S115 mouse mammary tumor cell line, as well as androgen receptors transfected into CV-1 and HeLa cells. In all cases, Bicalutamide behaves as a pure antiandrogen and inhibits gene expression and cell growth stimulated by androgen. Studies with the LNCaP cell line are particularly interesting, as these cells contain a mutated androgen receptor (codon 868, Thr-->Ala), which behaves idiosyncratically with other antiandrogens (cyproterone acetate and flutamide): both these antiandrogens act as agonists in this cell line and stimulate proliferation. Studies in vivo show that Bicalutamide is a potent antiandrogen in the rat. In immature, castrated male rats treated daily with testosterone propionate, Bicalutamide produces a profound inhibition of accessory sex organ (ventral prostate and seminal vesicles) growth at oral doses as low as 0.25 mg/kg; it is more active in this test than flutamide or cyproterone acetate. In mature male rats, daily oral doses of Bicalutamide produce a dose-related reduction in weights of the ventral prostate glands and seminal vesicles: in this test, Bicalutamide is around five times as potent as flutamide. In contrast to flutamide, which produces dose-related, marked increases in serum luteinizing hormone (LH) and testosterone as a consequence of the central inhibition of the negative feedback effects of androgens on the hypothalamic-pituitary-tests axis, Bicalutamide has little effect on serum LH and testosterone; i.e., it is peripherally selective. The peripheral selectivity of Bicalutamide in the rat is not due to differences between the prostate versus hypothalamic or pituitary receptors, as Bicalutamide reverses the suppressive effect of testosterone on luteinizing hormone-releasing hormone (LHRH) secretion from hypothalamic slices in vitro and is as effective as flutamide at sensitizing the pituitary gland to secrete LH in response to administered LHRH. The peripheral selectivity of Bicalutamide has now been shown to be due to poor penetration across the blood-brain barrier: tissue distribution studies with [3H]Bicalutamide show that although it is concentrated in the organs of metabolism and secretion as well as in the prostate, the pituitary glands, and the seminal vesicles, levels in the hypothalamus and the central nervous system (CNS) are much lower than in blood. Indeed, it is probable that levels found in the CNS reflect levels of blood contamination. In dogs, Bicalutamide has exquisite potency and causes dose-related atrophy of the prostate gland and epididymides; with an oral ED50 of 0.1 mg/kg, it is around 50 times as potent as flutamide in this species and also more potent than the steroidal antiandrogen WIN49596 and the 5 alpha-reductase inhibitor MK-906. Even at substantial multiples of the active dose (up to 100 mg/kg orally), Bicalutamide failed to increase serum testosterone, so it is also peripherally selective in the dog.

Nonsteroidal antiandrogens. Synthesis and structure-activity relationships of 3-substituted derivatives of 2-hydroxypropionanilides.[Pubmed:3361581]

J Med Chem. 1988 May;31(5):954-9.

A series of 3-(substituted thio)-2-hydroxypropionanilides and some corresponding sulfones and sulfoxides of general structure 7, in which R' is methyl or trifluoromethyl, were prepared and tested for antiandrogen activity. Members of the trifluoromethyl series (7, R' = CF3) generally exhibited partial androgen agonist activity whereas the members of the methyl series (7, R' = CH3) were pure antagonists. Lead optimization in the methyl series has led to the discovery of novel, potent antiandrogens, which are peripherally selective. One of these, (RS)-4'-cyano-3-[(4-fluorophenyl)sulfonyl]-2-hydroxy-2-methyl-3'- (trifluoromethyl)propionanilide, 40 (ICI 176334), is being developed currently for the treatment of androgen-responsive benign and malignant disease.

ICI 176,334: a novel non-steroidal, peripherally selective antiandrogen.[Pubmed:3625091]

J Endocrinol. 1987 Jun;113(3):R7-9.

Pure antiandrogens, like flutamide, antagonize androgen action both peripherally and centrally at the hypothalamic-pituitary axis, which leads to an increase in LH and testosterone secretion. A new non-steroidal antiandrogen ICI 176,334 [2RS)-4'-cyano-3-(4-fluorophenylsulphonyl)-2-hydroxy-2-methyl-3'- trifluoromethyl)propion-anilide) has now been discovered which causes regression of the accessory sex organs but does not increase serum concentrations of LH and androgens. ICI 176,334 binds to rat prostate androgen receptors with an affinity around fourfold that of hydroxyflutamide. When administered s.c. concurrently with testosterone propionate (200 micrograms/kg) for 7 days to immature castrated rats, ICI 176,334 (10 mg/kg) significantly (P less than 0.001) inhibited growth of the seminal vesicles and ventral prostate gland. Oral administration of ICI 176,334 at doses of 1, 5 and 25 mg/kg for 14 days to adult rats caused a dose-related reduction in accessory sex organ weights but had no effect on the testes. None of these doses caused a significant increase in serum LH and testosterone. Flutamide was around fourfold less potent and significantly increased serum LH and testosterone at the higher doses. ICI 176,334 was well tolerated. ICI 176,334 should, therefore, prove useful for the treatment of androgen-responsive benign and malignant diseases.