| Bioactivity | Abiraterone is a potent and irreversible CYP17A1 inhibitor with antiandrogen activity, which inhibits both the 17α-hydroxylase and 17,20-lyase activity of the cytochrome p450 enzyme CYP17 with IC50s of 2.5 nM and 15 nM, respectively. | ||||||||||||
| Target | IC50:17α-hydroxylase (2.5 nM), 17,20-lyase (15 nM) | ||||||||||||
| Invitro | Significant inhibition of proliferation of the AR-positive prostate cancer cell lines LNCaP and VCaP with doses of Abiraterone ≥5 μM is confirmed[2]. Abiraterone shows IC50 values of 15 nM and 2.5 nM for the 17,20-lyase and 17α-hydroxylase (CYP17 is a bifunctional enzyme with both 17α-hydroxylase and 17,20-lyase activity). Abiraterone inhibits human 17,20-lyase and 17α-hydroxylase with IC50 of 27 and 30 nM respectively[3]. Abiraterone inhibits recombinant human 3βHSD1 and 3βHSD2 activity with competitive Ki values of 2.1 and 8.8 μM. 10 μM Abiraterone is sufficient to completely block synthesis of 5α-dione and DHT in both cell lines.Treatment with abi significantly inhibited CRPC progression in the robustly growing subset, effectively putting a ceiling on tumor growth over 4 weeks of treatment (P<0.00001). [3H]-dehydroepiandrosterone (DHEA) depletion and Δ4-androstenedione (AD) accumulation are inhibited by Abiraterone in LNCaP, with an IC50<1 μM[4]. | ||||||||||||
| In Vivo | The 0.5 mmol/kg/d Abiraterone treatment dose is previously shown to yield serum concentrations of about 0.5 to 1 μM. Xenograft tumor growth in the control group is widely variable, with some tumors growing slowly and only a subset of tumors exhibiting robust growth[4]. Following i.v. administration (5 mg/kg) the clearance (Cl) and volume of distribution (Vd) are found to be 31.2 mL/min/kg and 1.97 L/kg, respectively. The AUC0-∞ (area under the plasma concentration-time curve from time zero to infinity time point) is found to be 2675 ng*h/mL. The terminal half-life (t1/2) is 0.73 h. Because of high clearance, Abiraterone (ART) is quantifiable only until 2 h following i.v. administration[5]. | ||||||||||||
| Name | Abiraterone | ||||||||||||
| CAS | 154229-19-3 | ||||||||||||
| Formula | C24H31NO | ||||||||||||
| Molar Mass | 349.51 | ||||||||||||
| Appearance | Solid | ||||||||||||
| Transport | Room temperature in continental US; may vary elsewhere. | ||||||||||||
| Storage |
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| Reference | [1]. Attard G, et al. Phase I clinical trial of a selective inhibitor of CYP17, abiraterone acetate, confirms that castration-resistant prostate cancer commonly remains hormone driven. J Clin Oncol. 2008 Oct 1;26(28):4563-71. [2]. Richards J, et al. Interactions of abiraterone, eplerenone, and prednisolone with wild-type and mutant androgen receptor: a rationale for increasing abiraterone exposure or combining with MDV3100. Cancer Res. 2012 May 1;72(9):2176-82. [3]. Stein MN, et al. Androgen synthesis inhibitors in the treatment of castration-resistant prostate cancer. Asian J Androl. 2014 May-Jun;16(3):387-400. [4]. Li R, et al. Abiraterone inhibits 3β-hydroxysteroid dehydrogenase: a rationale for increasing drug exposure in castration-resistant prostate cancer. Clin Cancer Res. 2012 Jul 1;18(13):3571-9. [5]. Kumar SV, et al. Validated RP-HPLC/UV method for the quantitation of abiraterone in rat plasma and its application to a pharmacokinetic study in rats. Biomed Chromatogr. 2013 Feb;27(2):203-7. [6]. Stein MN, et al. Androgen synthesis inhibitors in the treatment of castration-resistant prostate cancer. Asian J Androl. 2014 May-Jun;16(3):387-400. |