Discovery of a selective inhibitor of oncogenic B-Raf kinase with potent antimelanoma activity.
BRAF(V600E) is the most frequent oncogenic protein kinase mutation known. Furthermore, inhibitors targeting "active" protein kinases have demonstrated significant utility in the therapeutic repertoire against cancer. Therefore, we pursued the development of specific kinase inhibitors targeting B-Raf, and the V600E allele in particular. By using a structure-guided discovery approach, a potent and selective inhibitor of active B-Raf has been discovered. PLX4720, a 7-azaindole derivative that inhibits B-Raf(V600E) with an IC(50) of 13 nM, defines a class of kinase inhibitor with marked selectivity in both biochemical and cellular assays. PLX4720 preferentially inhibits the active B-Raf(V600E) kinase compared with a broad spectrum of other kinases, and potent cytotoxic effects are also exclusive to cells bearing the V600E allele. Consistent with the high degree of selectivity, ERK phosphorylation is potently inhibited by PLX4720 in B-Raf(V600E)-bearing tumor cell lines but not in cells lacking oncogenic B-Raf. In melanoma models, PLX4720 induces cell cycle arrest and apoptosis exclusively in B-Raf(V600E)-positive cells. In B-Raf(V600E)-dependent tumor xenograft models, orally dosed PLX4720 causes significant tumor growth delays, including tumor regressions, without evidence of toxicity. The work described here represents the entire discovery process, from initial identification through structural and biological studies in animal models to a promising therapeutic for testing in cancer patients bearing B-Raf(V600E)-driven tumors.
Tsai
James
J
Plexxikon, Inc., 91 Bolivar Drive, Berkeley, CA 94710, USA.
Lee
John T
JT
Wang
Weiru
W
Zhang
Jiazhong
J
Cho
Hanna
H
Mamo
Shumeye
S
Bremer
Ryan
R
Gillette
Sam
S
Kong
Jun
J
Haass
Nikolas K
NK
Sproesser
Katrin
K
Li
Ling
L
Smalley
Keiran S M
KS
Fong
Daniel
D
Zhu
Yong-Liang
YL
Marimuthu
Adhirai
A
Nguyen
Hoa
H
Lam
Billy
B
Liu
Jennifer
J
Cheung
Ivana
I
Rice
Julie
J
Suzuki
Yoshihisa
Y
Luu
Catherine
C
Settachatgul
Calvin
C
Shellooe
Rafe
R
Cantwell
John
J
Kim
Sung-Hou
SH
Schlessinger
Joseph
J
Zhang
Kam Y J
KY
West
Brian L
BL
Powell
Ben
B
Habets
Gaston
G
Zhang
Chao
C
Ibrahim
Prabha N
PN
Hirth
Peter
P
Artis
Dean R
DR
Herlyn
Meenhard
M
Bollag
Gideon
G
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D004926:Escherichia coli; D006801:Humans; D007211:Indoles / Q000737:chemistry* / Q000627:therapeutic use; D020128:Inhibitory Concentration 50; D008545:Melanoma / Q000188:drug therapy*; D051379:Mice; D016513:Mice, SCID; D008958:Models, Molecular; D015394:Molecular Structure; D009857:Oncogenes / Q000235:genetics*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000737:chemistry* / Q000627:therapeutic use; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors* / Q000235:genetics; D013449:Sulfonamides / Q000737:chemistry* / Q000627:therapeutic use
D007211:Indoles; C528407:PLX 4720; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf