Table 1.

Biochemical IC₅₀ values for inhibition of KIT kinase activity in transfected cells

1° Mutation	2° Mutation	Imatinib	Sorafenib	Sunitinib
V560D	None	<100	<100	<100
V560D	V654A	1,600	560a	<100
V560D	T670I	>5,000	200a	<100
V560D	D816H	1,990	1,930	>1,000
V560D	D820A	4,000	<100	ND
V560D	D820G	3,255	480a	>1,000
V560D	N822K	2,820	480a	>1,000
V560D	Y823D	2,100	280a	>1,000
WT	None	3,400	2,700	<100
D816V	None	>5,000	>5,000	>1,000
KIT insAY502-503	None	3,970	1,829a	<100
KIT insAY502-503	V654A	3,100	590a	100
KIT insAY502-503	D816H	4,930	1,820a	>1,000
KIT insAY502-503	D820G	2,640	1,380a	ND

NOTE: The values for imatinib, sorafenib, and sunitinib represent the biochemical IC₅₀ expressed in nmol/L units for the listed single mutant or compound mutant kinases. WT indicates the results for wild-type (unmutated), KIT ligand-stimulated KIT kinase. The IC₅₀ values for imatinib and sorafenib are from direct head-to-head comparison from a minimum of 3 replicate experiments. The IC₅₀ values for sunitinib are from a previous publication from our group (6).

Abbreviation: ND, not determined.

^aP < 0.05 sorafenib IC₅₀ compared with imatinib IC₅₀.