Comparison of the pharmacokinetics (PK) of galeterone novel oral formulations.

Abstract

e16075 Background: Galeterone (gal) is an orally available steroid analog for the treatment of castration resistant prostate cancer (CRPC). A significant food effect, similar to abiraterone, was found when gal, as powder in capsule (PIC), was dosed in a phase I CRPC trial and confirmed in a PK study in human volunteers.The objective of this study was to assess single-dose PK of gal after reformulation and to evaluate effect of food. Methods: In this single-center open-label study, 24 male subjects were assigned to receive once daily doses of between 100 and 3400 mg in either a 3-treatment, 3-period or 4-treatment, 4-period dose scheme. Treatment periods were separated by 7-day washout intervals. Plasma concentrations were measured over 72 hours to assess PK. Two novel tablet formulations were administered in 100 mg doses under fasted and/or fed condition compared to 2600 mg-PIC administered under fed conditions. Escalating doses of PIC (975 to 2600 mg) and tablet (850 to 3400 mg) formulations were evaluated to assess linearity. Results: Gal was well tolerated. Food effect has been negated with the tablet. Exposure from 1700 mg galeterone tablet (fed or fasted) is comparable to a 2,600 mg dose of PIC (fed) (Table). For tablet, AUC(inf) increased in a dose-related and dose-proportional manner from 6,689 ± 2,602 hxng/mL (850 mg) to 20131 ± 9,930 hxng/mL (2,550 mg). Conclusions: The tablet formulation negates the food effect previously observed. Gal may be dosed either fed or fasted with no difference in absorption, which reduces intra-patient variability in exposure. Tablet has more consistent bioavailability and a linear increase in AUC between escalating doses. [Table: see text]