TABLE 3.

Summary of IC₅₀ values for 17α-hydroxypregnenolone 17,20-lyase inhibition (targeted reaction), progesterone and pregnenolone hydroxylation (off-target reactions), and resulting selectivity ratios

The IC₅₀ values are the average of two independent experiments ± S.E. Within each experiment, each inhibitor concentration was evaluated in duplicate or triplicate.

Inhibitor	Lyase IC50	Progesterone Hydroxylase IC50	Progesterone Hydroxylase IC50 Lyase IC50	Pregnenolone Hydroxylase IC50	Pregnenolone Hydroxylase IC50 Lyase IC50
	nM	nM		nM
Abiraterone	36 ± 2	76 ± 5	2.1 ± 0.2	121 ± 7	3.3 ± 0.3
Galeterone	100 ± 10	130 ± 10	1.3 ± 0.2	150 ± 20	1.5 ± 0.3
(S)-orteronel	210 ± 20	950 ± 70	4.5 ± 0.5	700 ± 100	3.3 ± 0.6
(R)-orteronel	460 ± 90	4000 ± 300	8 ± 2	5000 ± 1000	11 ± 3
(S)-seviteronel	430 ± 40	1170 ± 90	2.7 ± 0.3	700 ± 100	2.1 ± 0.4
(R)-seviteronel	5000 ± 1000	11,300 ± 900	2.3 ± 0.5	N/D	N/D

N/D, not determined.