154229-21-7Relevant articles and documents
Slow-, tight-binding inhibition of CYP17A1 by abiraterone redefines its kinetic selectivity and dosing regimen
Cheong, Eleanor Jing Yi,Nair, Pramod C.,Neo, Rebecca Wan Yi,Tu, Ho Thanh,Lin, Fu,Chiong, Edmund,Esuvaranathan, Kesavan,Fan, Hao,Szmulewitz, Russell Z.,Peer, Cody J.,Figg, William D.,Chai, Christina Li Lin,Miners, John O.,Chan, Eric Chun Yong
supporting information, p. 438 - 451 (2020/09/04)
Substantial evidence underscores the clinical efficacy of inhibiting CYP17A1-mediated androgen biosynthesis by abiraterone for treatment of prostate oncology. Previous structural analysis and in vitro assays revealed inconsistencies surrounding the nature and potency of CYP17A1 inhibition by abiraterone. Here, we establish that abiraterone is a slow-, tight-binding inhibitor of CYP17A1, with initial weak binding preceding the subsequent slow isomerization to a high-affinity CYP17A1-abiraterone complex. The in vitro inhibition constant of the final high-affinity CYP17A1-abiraterone complex ( ( Ki? = 0.39 nM )yielded a binding free energy of -12.8 kcal/mol that was quantitatively consistent with the in silico prediction of 214.5 kcal/mol. Prolonged suppression of dehydroepiandrosterone (DHEA) concentrations observed in VCaP cells after abiraterone washout corroborated its protracted CYP17A1 engagement. Molecular dynamics simulations illuminated potential structural determinants underlying the rapid reversible binding characterizing the two-step induced-fit model. Given the extended residence time (42 hours) of abiraterone within the CYP17A1 active site, in silico simulations demonstrated sustained target engagement even whenmost abiraterone has been eliminated systemically. Subsequent pharmacokineticpharmacodynamic (PK-PD) modeling linking time-dependent CYP17A1 occupancy to in vitro steroidogenic dynamics predicted comparable suppression of downstream DHEA-sulfate at both 1000- and 500-mg doses of abiraterone acetate. This enabled mechanistic rationalization of a clinically reported PK-PD disconnect, inwhich equipotent reduction of downstreamplasma DHEAsulfate levels was achieved despite a lower systemic exposure of abiraterone. Our novel findings provide the impetus for reevaluating the current dosing paradigmof abiraterone with the aim of preserving PD efficacy while mitigating its dose-dependent adverse effects and financial burden. SIGNIFICANCE STATEMENT With the advent of novel molecularly targeted anticancer modalities, it is becoming increasingly evident that optimal dose selection must necessarily be predicated on mechanistic characterization of the relationships between target exposure, drug-target interactions, and pharmacodynamic endpoints. Nevertheless, efficacy has always been perceived as being exclusively synonymous with affinity-based measurements of drug-target binding. This work demonstrates how elucidating the slow-, tight-binding inhibition of CYP17A1 by abiraterone via in vitro and in silico analyses was pivotal in establishing the role of kinetic selectivity in mediating time-dependent CYP17A1 engagement and eventually downstream efficacy outcomes.
A acetate synthesis method
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Paragraph 0054; 0076; 0077; 0078, (2017/08/31)
The invention relates to a synthesis method of abiraterone acetate. According to the synthesis method of the abiraterone acetate, a compound 1 is taken as a revelator, and the abiraterone acetate is prepared through steps such as esterification, Grignard reagent reaction, dehydration, acylation, reduction, acetylation and the like.
A-ring modified steroidal azoles retaining similar potent and slowly reversible CYP17A1 inhibition as abiraterone
Garrido, Mariana,Peng, Hwei-Ming,Yoshimoto, Francis K.,Upadhyay, Sunil K.,Bratoeff, Eugene,Auchus, Richard J.
, p. 1 - 10 (2014/04/03)
Abiraterone acetate is a potent inhibitor of human cytochrome P450c17 (CYP17A1, 17α-hydroxylase/17,20-lyase) and is clinically used in combination with prednisone for the treatment of castration-resistant prostate cancer. Although many studies have documented the potency of abiraterone (Abi) in a variety of in vitro and in vivo systems for several species, the exact potency of Abi for human CYP17A1 enzyme has not yet been determined, and the structural requirements for high-potency steroidal azole inhibitors are not established. We synthesized 4 Abi analogs differing in the A-B ring substitution patterns: 3α-hydroxy-Δ4-Abi (13), 3-keto- Δ4-Abi (11), 3-keto-5α-Abi (6), and 3α-hydroxy- 5α-Abi (5). We measured the spectral binding constants (Ks) using purified and modified human CYP17A1 along with the determination constants (Ki) applying a native human CYP17A1 enzyme in yeast microsomes for these compounds as well as for ketoconazole. For Abi, 3-keto- Δ4-Abi, 3-keto-5α-Abi, and 3α-hydroxy-5α-Abi, the type 2 spectral changes gave the best fit for a quadratic equation, since in these experiments Ks values were 0.1-2.6 nM, much lower than that for ketoconazole and 3α-hydroxy-Δ4-Abi (Ks values were 140 and 1660 nM, respectively). Inhibition experiments showed mixed inhibition patterns with Ki values of 7-80 nM. Abi dissociation from the CYP17A1-Abi complex was incomplete and slow; the t1/2 for dissociation was 1.8 h, with 55% of complex remaining after 5 h. We conclude that Abi and the 3 related steroidal azoles (3-keto-Δ4-Abi, 3-keto-5α-Abi, and 3α-hydroxy-5α-Abi), which also mimic natural substrates, are extraordinarily potent inhibitors of human CYP17A1, whereas the 3α-hydroxy-Δ4-Abi is moderately potent and comparable to ketoconazole.