Pharmacokinetic profile of 3beta-hydroxy-17-(1H-1,2,3-triazol-1-yl)androsta-5,16-diene (VN/87-1), a potent androgen synthesis inhibitor, in mice

Alkynyl phosphonate DNA: a versatile "click"able backbone for DNA-based biological applications

Major hurdles associated with DNA-based biological applications include, among others, targeted cell delivery, undesirable nonspecific effects, toxicity associated with various analogues or the reagents used to deliver oligonucleotides to cells, and stability toward intracellular enzymes. Although a plethora of diverse analogues have been investigated, a versatile methodology that can systematically address these challenges has not been developed. In this contribution, we present a new, Clickable, and versatile chemistry that can be used to rapidly introduce diverse functionality for studying these various problems. As a demonstration of the approach, we synthesized the core analogue, which is useful for introducing additional functionality, the triazolylphosphonate, and present preliminary data on its biological properties. We have developed a new phosphoramidite synthon--the alkynyl phosphinoamidite, which is compatible with conventional solid-phase oligonucleotide synthesis. Postsynthesis, the alkynylphosphonate can be functionalized via "Click" chemistry to generate the 1,2,3-triazolyl or substituted 1,2,3-triazolyl phosphonate-2'-deoxyribonucleotide internucleotide linkage. This manuscript describes the automated, solid-phase synthesis of mixed backbone oligodeoxyribonucleotides (ODNs) having 1,2,3-triazolylphosphonate (TP) as well as phosphate or thiophosphate internucleotide linkages and also 2'-OMe ribonucleotides and locked nucleic acids (LNAs) at selected sites. Nuclease stability assays demonstrate that the TP linkage is highly resistant toward 5'- and 3'-exonucleases, whereas melting studies indicate a slight destabilization when a TP-modified ODN is hybridized to its complementary RNA. A fluorescently labeled 16-mer ODN modified with two TP linkages shows efficient cellular uptake during passive transfection. Of particular interest, the subcellular distribution of TP-modified ODNs is highly dependent on cell type; a significant nuclear uptake is observed in HeLa cells, whereas diffuse cytoplasmic fluorescence is found in the WM-239A cell line. Cytoplasmic distribution is also present in human neuroblastoma cells (SK-N-F1), but Jurkat cells show both diffuse and punctate cytoplasmic uptake. Our results demonstrate that triazolylphosphonate ODNs are versatile additions to the oligonucleotide chemist's toolbox relative to designing new biological research reagents.

Synthesis of steroid-ferrocene conjugates of steroidal 17-carboxamides via a palladium-catalyzed aminocarbonylation--copper-catalyzed azide-alkyne cycloaddition reaction sequence

Steroids with the 17-iodo-16-ene functionality were converted to ferrocene labeled steroidal 17-carboxamides via a two step reaction sequence. The first step involved the palladium-catalyzed aminocarbonylation of the alkenyl iodides with prop-2-yn-1-amine as the nucleophile in the presence of the Pd(OAc)(2)/PPh(3) catalyst system. In the second step, the product N-(prop-2-ynyl)-carboxamides underwent a facile azide-alkyne cycloaddition with ferrocenyl azides in the presence of CuSO(4)/sodium ascorbate to produce the steroid-ferrocene conjugates. The new compounds were obtained in good yield and were characterized by (1)H and (13)C NMR, IR, MS and elemental analysis.

Potent CYP17 inhibitors: improved syntheses, pharmacokinetics and anti-tumor activity in the LNCaP human prostate cancer model

A facile preparation of azolyl steroids, VN/85-1 and VN/87-1 (potent inhibitors of CYP17) has been developed. This process without tedious chromatographic separations improved the overall yields from 55 and 45% to 70 and 65% for VN/85-1 and VN/87-1, respectively. Pharmacokinetic studies of VN/85-1 were conducted in male SCID mice. Following subcutaneous (s.c.) administration of 100mg/kg of VN/85-1, peak plasma level of 16.73 microg/ml occurred after 45 min, and the compound was cleared rapidly with a t(1/2) of 52.34 min. The bioavailability of VN/85-1 after s.c. administration was 83.0%. VN/85-1 was also rapidly metabolized to the corresponding 3-oxo-4-ene analog, 17-(1H-imidazol-1-yl)androsta-4,16-diene-3-one (VN/108-1). In our attempt to optimize the anti-tumor efficacy of these two CYP17 inhibitors, we studied their anti-tumor efficacies in male SCID mice bearing LNCaP tumor xenografts, utilizing various drug doses and drug scheduling. Three times a day dose regimen (3 x dose regimen) of VN/85-1 was more effective than a once daily dose. In contrast, 3 x dose regimen doses of VN/87-1 were less effective than the once daily dose. However, at their effective dosage regimes, VN/85-1 and VN/87-1 were each as effective as castration and more effective than finasteride or casodex, an anti-androgen used for prostate cancer (PC) therapy. For all of the treatments, there was a strong correlation between the tumor volumes and other associated parameters, such as, tumor weights, and serum testosterone (T) and PSA levels. These results indicate that VN/85-1 or VN/87-1 may be useful in the treatment of hormone-dependent prostate cancer.

Pharmacokinetics of novel inhibitors of androgen synthesis after intravenous administration in mice

PURPOSE

The pharmacokinetics of several new androgen synthesis inhibitors were investigated after intravenous administration in mice. The inhibitors were: 3beta-hydroxy-17-(1 H-imidazol-1-yl)androsta-5,16-diene (VN/85-1), 3beta-hydroxy-17-(1 H-1,2,3-triazol-1-yl)androsta-5,16-diene (VN/87-1), 17-(1 H-imidazol-1-yl)androsta-4,16-diene-3-one (VN/108-1) and 17-(5'-isoxazolyl)androsta-4,16-dien-3-one (L-39).

METHODS

Male Balb/c mice were injected with VN/85-1, VN/87-1, VN/108-1 or L-39 at 10, 25 and 50 mg/kg doses. Blood was collected at various times after drug administration via the eye orbit. The concentrations of VN/85-1, VN/87-1, VN/108-1 or L-39 in plasma were analyzed by a reversed-phase HPLC method with UV detection.

RESULTS

The plasma levels of VN/85-1, VN/87-1, VN/108-1 and L-39 declined biexponentially with terminal elimination half-lives ranging from 0.88 to 1.77 h. The terminal half-lives for VN/87-1, VN/85-1 and VN/108-1 were similar. However, the terminal half-life for L-39 was significantly longer than those for VN/87-1, VN/85-1 and VN/108-1. The systemic clearance values for the steroids ranged from 0.85 to 10.91 l/h per kg with a rank order of their clearance of L-39>VN/87-1>VN/108-1>VN/85-1. The apparent volumes of distribution at steady state for the steroids ranged from 0.58 to 18.85 l/kg with a rank order of their apparent V(ss) of L-39>VN/87-1>VN/85-1>VN/108-1. The clearance and apparent V(ss) for all four compounds were dose-independent following intravenous administration of doses up to 50 mg/kg.

CONCLUSIONS

VN/85-1, VN/87-1, VN/108-1 and L-39 are rapidly cleared from the systemic circulation and display linear pharmacokinetics in mice. The information presented may be used to improve the disposition profiles and activities of the steroidal inhibitors of androgen synthesis in animal models of prostate cancer.