Discovery of RAF265: A Potent mut-B-RAF inhibitor for the treatment of metastatic melanoma

Article abstract of DOI:10.1021/ml500526p

Abrogation of errant signaling along the MAPK pathway through the inhibition of B-RAF kinase is a validated approach for the treatment of pathway-dependent cancers. We report the development of imidazo-benzimidazoles as potent B-RAF inhibitors. Robust in

Full text of DOI:10.1021/ml500526p

Letter
pubs.acs.org/acsmedchemlett
Discovery of RAF265: A Potent mut-B-RAF Inhibitor for the
Treatment of Metastatic Melanoma
Teresa E. Williams, Sharadha Subramanian, Joelle Verhagen, Christopher M. McBride, Abran Costales,
Leonard Sung, William Antonios-McCrea, Maureen McKenna, Alicia K. Louie, Savithri Ramurthy,
Barry Levine, Cynthia M. Shafer, Timothy Machajewski, Paul A. Renhowe, Brent A. Appleton,
Payman Amiri, James Chou, Darrin Stuart, Kimberly Aardalen, and Daniel Poon*
Global Discovery Chemistry, Oncology and Exploratory Chemistry, Novartis Institutes for Biomedical Research, 5300 Chiron Way,
Emeryville, California 94608, United States
*
S Supporting Information
ABSTRACT: Abrogation of errant signaling along the MAPK pathway through
the inhibition of B-RAF kinase is a validated approach for the treatment of
pathway-dependent cancers. We report the development of imidazo-benzimida-
zoles as potent B-RAF inhibitors. Robust in vivo efficacy coupled with correlating
pharmacokinetic/pharmacodynamic (PKPD) and PD-efficacy relationships led to
the identification of RAF265, 1, which has advanced into clinical trials.
KEYWORDS: B-RAF, MAP, VEGF, serine/threonine kinases, tyrosine kinases
he MAPK signaling pathway, consisting of RAS/RAF/
MEK/ERK, transduces input from cell surface receptors
continued efforts in this area, which resulted in the discovery of
V600E
T
RAF265 (1), a potent inhibitor of B-RAF
with
to nuclear transcription factors thereby regulating cellular
complementary VEGFR and PDGFR activity.
As reported previously, amido-2-arylaminobenzimidazoles,
such as 2 (Table 1), have demonstrated potent biochemical
1
proliferation, differentiation, and survival. Dysregulation of this
pathway through an activating mutation in B-RAF (V600E)
occurs in ∼50% of melanomas and has made RAF the subject
inhibition as well as cellular activity in target modulation and
2
of many drug discovery efforts. Validation for targeting B-
V600E
V600E
proliferation assays against SKMEL-28, a B-RAF
melanoma cell line.
harboring
RAF
as an effective chemotherapeutic approach has been
5
−7,9
provided by the recent approval of vemurafenib (Roche) and
dabrafenib (GSK) by the FDA for the treatment of metastatic
Further development of the series did not result in further
improvement in cellular potency; however, a simple and
3
−5
melanoma (Figure 1).
Previous publications from our laboratories have described
the development of the 2-arylaminobenzimidazole scaffold as a
platform for improved mut-RAF potency and pharmacokinetics
over sorafenib (Bayer, Figure 1), an earlier receptor tyrosine
kinase inhibitor approved for the treatment of renal cell and
a
Table 1. Key Amide Transformations
6
−8
hepatocellular carcinoma.
In this report, we describe our
B-RAFV600E
b
pERK SKMEL-28
c
SKMEL-28
d
Cpd
R1
2
3
4
−CONHMe
−NHCOMe
2-imidazolyl
0.045 (1)
0.003 (1)
0.090 (1)
0.28 (3)
0.044 (7)
0.39 (1)
0.90 (3)
0.18 (8)
a
IC50 in μM. Numbers in parentheses represent number of
b
V600E
6,7
determinations. B-RAF
within 2-fold of the mean value of the control. pERK SKMEL target
modulation. Assay variability within 3-fold of mean value for
applicable entries. SKMEL-28 cell proliferation assay.
enzymatic assay.
Assay variability
c
5
,9
d
5,9
Assay
variability within 3-fold of mean value.
Received: December 19, 2014
Accepted: July 20, 2015
Figure 1. Structures of vemurafenib, dabrafenib, and sorafenib.
©
XXXX American Chemical Society
A
DOI: 10.1021/ml500526p
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX

ACS Medicinal Chemistry Letters
Letter
effective inversion of the amide connectivity as embodied in 3
realized a marked increase in cellular potency. Unfortunately,
Table 2. Selected Data from Anilide and Imidazole SAR
a
7
Survey
some substituted reverse amide analogues suffered from plasma
instability, and an alternative moiety was sought. Utilizing an
isostere replacement approach, cyclization of the forward amide
of 2 led to the simple imidazole analogue 4, which
demonstrated a similar in vitro potency profile and provided a
suitable starting point for further investigation.
b
c
d
Cpd
R2
R3
pERK SKMEL-28
SKMEL-28 CYP3A4
The general synthetic route for the imidazole series is
represented by the synthesis of 1 as depicted in Scheme 1. The
4
3-tBu
H
0.39 (1)
0.48 (2)
0.12 (2)
0.13 (1)
0.042 (1)
0.78 (1)
0.21 (4)
0.62 (1)
0.14 (18)
1.8 (2)
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
3-tBu
Ph
1.1 (1)
7.1 (1)
10 (3)
34 (1)
3.3 (1)
3-tBu
CF3
CF3
CF3
CF3
CF3
Me
0.12 (2)
0.23 (1)
0.050 (1)
1.62 (1)
0.6 (4)
a
Scheme 1. Synthesis of 1
4-tBu
2-F, 5-tBu
3-CF3
>40 (1)
26 (2)
2-F, 5-CF3
2-F, 5-CF3
4-CF3
0.74 (1)
0.16 (12)
3.4 (1)
>40 (3)
CF3
a
IC50 in μM. Numbers in parentheses represent number of
b
7,8 c
determinations. pERK SKMEL target modulation.
cell proliferation assay.
SKMEL28
7,8 d
CYP3A4 inhbition assay using midazolam
as subtrate. Assay variability within 2-fold of mean value for applicable
entries. See Supporting Information for CYP3A4 assay conditions and
isoform inhibition of 1.
analogues, introduction of a fluorine at the 2-position gave a
further boost in cellular potency (13, 15). Unfortunately, all 3-
and 5-alkyl substituted analogues suffered from poor exposure
in pharmacokinetic (PK) studies. A solution was found in the
para- and meta-CF analogues (1, 14), which provided a similar
3
level of potency as with the alkyl analogues along with greater
metabolic stability. In examining the imidazole substitution
pattern, it was observed that electron withdrawing groups
improved cellular potency as illustrated in the matched pair
analyses of 4, 11 and 15, 16. Gratifyingly, imidazole
substitution also provided incremental reduction in CYP3A4
inhibition (4, 10, 11); however, the CYP3A4 profile could be
further modulated by the anilide substitution pattern. Moving
the tBu group from the 3-position to the 4-position (12)
resulted in an improvement in CYP3A4 selectivity, which also
a
Reagents and conditions: (a) 3-nitro-4-aminophenol, K CO ,
2
3
DMSO, 100 °C, 74%; (b) TFAA, DCM, 0 °C; Me SO , TBACl,
1
DCM, 58%; (e) 1,1-dibromo-3,3,3-trifluoroacetone, NaOAc, water,
1
2
4
0% NaOH, 76%; (c) LAH, THF 0 °C; NaBH , 46%; (d) MnO ,
4
2
14
00 °C; NH OH, MeOH rt, 91%; (f) 10% Pd/C, H , MeOH/EtOAc,
4
2
9
6%; (g) 4-trifluoromethylphenyl thioisocyanate, FeCl , 40−60%.
3
translated into the corresponding CF analogue 1. With a
favorable balance of cellular potency and CYP3A4 selectivity, 1
was selected for further investigation.
3
central phenyl-pyridyl ether 6 was assembled from the S Ar
reaction of chloropyridine 5 with 3-nitro-4-aminophenol.
N
Methylation of the anilino nitrogen was accomplished using
10,11
The crystal structure of 1 in truncated wt-B-RAF provided
insight as to how the molecule interacts with the target protein
phase transfer catalysis to give 7.
Reduction of the t-butyl
ester using LAH under strict temperature control, followed by
15
(
Figure 2). Binding occurred through a Type II, inactive-like
NaBH and MnO oxidation furnished aldehyde 8. Debus−
4
2
conformation where the DFG loop has adopted an “out”
Radziszewski cyclization with an in situ generated glyoxal
derived from 1,1-dibromo-3,3,3-trifluoroacetone furnished the
12
corresponding imidazole 9. Reduction of the nitroarene
followed by addition of 4-trifluoromethylphenyl thioisocyanate
1
3
and FeCl -promoted ring cyclization provided 1. All
3
compounds where biological data is presented have >95%
purity as determined by HPLC.
The simple, unadorned imidazole 4, while providing a useful
benchmark against the previous series, did not offer the cellular
potency desired and resulted in a significant CYP liability
(
CYP3A4 IC50 = 1.8 μM). An SAR campaign probing the
anilide and imidazole substitution patterns was undertaken to
address cellular potency and CYP3A4 inhibition of this series
(
Table 2).
Holding with previously reported SAR trends, 3- and 4-
position branched alkyl substituents of the anilide ring
Figure 2. Co-crystal structure of 1 bound to truncated wt-B-RAF at
3.2 Å resolution.
4
,5
conferred potency (4, 10−12).
For meta-substituted
B
DOI: 10.1021/ml500526p
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ACS Medicinal Chemistry Letters
Letter
a
Table 3. Biochemical Activities Against Select Tyrosine Kinases
Cpd
B-RAFV600E
VEGFR
c-KIT
PDGFRβ
LCK
FYN
SRC
2
3
4
0.045
0.003
0.090
0.055
0.020
0.005
0.002
0.030
0.070
0.020
0.010
0.003
0.020
0.020
0.020
0.010
0.001
0.31
0.065
0.003
0.20
2.0
0.005
0.002
0.040
0.22
0.002
1
1
1
0.001
0.006
>6.0
>10
>6.0
>10
a
IC50 in μM. All entries are single determinations. See ref 19 for a broader kinase survey of 1.
1
6
conformation. Of interest is the hinge region where the
imidazole is situated between Trp531 and Phe483. The
imidazole NH interacts with the carbonyl of Cys532, suggesting
assay (VEGFR IC50 = 0.19 μM). This level of activity was
V600E
similar to that observed against Ba/F3-B-RAF
(IC = 0.14
50
μM) and in the SKMEL-28 proliferation assay. Conversely, the
Ba/F3 cells expressing LCK, FYN, and SRC were not inhibited
reflecting success in achieving selectivity against these kinases.
that a potential role of the 5-CF substituent is to acidify the
3
NH-bond and facilitate a stronger hydrogen bonding
interaction. The pyridyl moiety makes a second hydrogen
bond to Cys532 that completes an efficient bidentate
interaction. The ring benzimidazolo nitrogen and the anilide
NH are found to hydrogen bond with the NH backbone of
Asp594 of the DFG loop and Glu501 of the αC-helix,
Together, these data indicated that along with potent inhibition
V600E
of B-RAF
, 1 also inhibited the VEGFR and PDGFR family
of kinases, which play critical roles in tumor angiogenesis.
Pathway inhibition and antiproliferative effects were
evaluated in a small panel of tumor cell lines (Figure 4).
1
7
respectively. The NMe of the benzimidazole fills the
selectivity pocket partially defined by the “gatekeeper” residue,
Thr529.
RAF265 (1) was found to be a potent inhibitor of B-
V600E
RAF
, wt-B-RAF, and C-RAF with IC s of 0.0005, 0.070,
50
and 0.019 μM, respectively. The kinase selectivity profile of 1
bore similarities to inhibitors of other serine/threonine and
16−19
tyrosine kinases, such as sorafenib.
All specific hydrogen
bonds between 1 and wt-B-RAF are with residues that are
conserved among the kinases (e.g Glu501 and Asp594). Within
the chemical series, consistent off targets included VEGFR,
PDGFβ, and c-Kit, all of which share a threonine or a similarly
sized valine residue at the gatekeeper position in the “back” or
“selectivity” pocket (Table 3).
Kinase profiling of each of the benzimidazolo archetypes (2,
3, 4) indicated little or no discrimination against a significant
segment of tyrosine kinases. However, within the imidazole
series, substitution at imidazole in the hinge region provided a
handle to address selectivity against the SRC family of kinases
Figure 4. In vitro target modulation and antiproliferation of RAF265
on MAPK-dependent tumor cell lines. IC50 in μM. All entries are
single determinations. See Supporting Information for assay details.
(11, 1). To understand the selectivity profile in a cellular
setting, 1 was evaluated in a panel of Ba/F3 cells whose
profileration was dependent on a range of protein kinases
2
0
(Figure 3).
In melanoma tumor cell lines expressing B-RAFV600E (A375,
Malme-3M, and WM-1799), 1 decreased phospho-ERK and
inhibited proliferation with IC50 ranging from 0.04 to 0.2 μM.
In contrast, cell lines that expressed wt-B-RAF, 1, failed to
suppress phospho-ERK levels and had weak antiproliferative
activity.
The activity against these kinase-dependent cell lines (KDR,
KIT, PDGFRb) recapitulated the biochemical findings and
were corroborated by a cell based receptor phosphorylation
Owing to the size and lipophilic nature of the molecule (MW
518, cLog P > 5), it was unsurprising that 1 exhibited poor
=
kinetic aqueous solubility (∼1 μM) and high plasma protein
21
binding (>99% PPB in mouse, rat, dog, and human). Despite
these drawbacks, 1 exhibited good to moderate oral
bioavailability across species, with dog being the lowest, when
dosed in single dose PK studies (Table 4). Total plasma
clearance is very low relative to hepatic blood flow, and the
plasma half-life across species is greater than 24 h, indicating
the possibility of accumulation in multidose settings.
In mouse PK studies, the high plasma protein binding and a
low volume of distribution of 1 would suggest sequestration
within the plasma compartment. In separate efficacy studies in
A375M xenograft models, 1 was able to distribute to the target
Figure 3. Inhibitory activity of 1 against kinase dependent Ba/F3 cell
lines. IC50 in μM. All entries are single determinations.
C
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ACS Medicinal Chemistry Letters
Letter
a
Table 4. In Vivo Pharmacokinetics of 1 Across Species
parameters
mouse
rat
dog
monkey
dose (mpk, iv/po)
5, 30
51
5, 20
>95
450
0.9
1.25, 5
35
1, 5
48
%F
AUC∞, po (μM·h)
CL (mL/min/kg)
Vss (L/kg)
4300
0.1
35
48
0.8
1.5
2.9
28
0.5
3.3
1.9
t1/2 (h)
41
46
27
a
Administered as a solution in 60%PEG400/40% PG.
and exert a pronounced pharmacological effect (Figures 5 and
).
6
Figure 6. Efficacy of 1 in A375M mouse xenograft. PD sampling taken
4
h post-third dose. Less than 15% body weight loss was observed in
the 100 mg/kg q2d dosing arm. See Supporting Information for more
details.
the 30 and 100 mg/kg dose, which resulted in significant
reductions in phospho-MEK levels compared to tumors from
the vehicle group, while the 10 mg/kg dose did not appreciably
alter phospho-MEK levels.
To conclude, we have developed a novel chemical series
derived from 2-arylaminobenzimidazoles, which were opti-
mized for cellular potency while balancing kinase selectivity and
ADME properties. These efforts resulted in the identification of
V600E
1
as a potent inhibitor of B-RAF
with complementary
VEGFR and PDGFR activity that demonstrated potent in vivo
target modulation and efficacy. Further development of this
molecule resulted in the advancement into clinical trials for the
2
2
treatment of metastatic melanoma.
Figure 5. PKPD snapshot from A375M model xenograft model. PD
sampling taken at noted time points post-third dose of the q4d arm.
The PD readouts of the 48 h time point are two separate blots of the
same tumor lysate sample. See Supporting Information for efficacy
data and experimental details.
ASSOCIATED CONTENT
Supporting Information
■
*
S
Experimental details for the synthesis and characterization of
select compounds, procedures for the biochemical and cellular
assays, in vivo analyses, and crystallographic conditions. The
Supporting Information is available free of charge on the ACS
Publications website at DOI: 10.1021/ml500526p.
Seeking to take advantage of the long PK half-life, a 32 day
multidose efficacy study examining the effect of intermittent
dosing regimens on target coverage was undertaken. Tumors
from a subset of mice from each study arm were harvested at
intervals post-third dose, and the corresponding lysates were
assayed for phospho-MEK levels by Western blot analysis
AUTHOR INFORMATION
Corresponding Author
■
*
E-mail: daniel.poon@novartis.com.
(
Figure 5). Dosing q2d maintained a Cmin trough level of ∼125
μM, which corrected for mouse plasma protein (99.6%)
yielding an effective free Cmin of ∼0.5 μM (A375M IC
Notes
=
The authors declare no competing financial interest.
50
0
.16 μM). The pharmacodynamic (PD) readout from the q4d
arm indicated significant target suppression out to 48 h
followed by complete signal recovery at 96 h, indicating that the
q2d dosing regimen would be optimal for target coverage.
To characterize the dose−response relationship, 1 was dosed
orally q2d at 10, 30, and 100 mg/kg in a 28 day mouse efficacy
study (Figure 6). Consistent with the results of the previous
study in Figure 5, 1 induced tumor regressions at the 100 mg/
kg, while at 30 mg/kg resulted in robust stasis or tumor growth
inhibition, and the 10 mg/kg dose demonstrated modest
inhibition of tumor growth relative to vehicle treated animals.
The PD results corroborated the earlier PKPD findings with
ACKNOWLEDGMENTS
■
The authors wish to acknowledge Mina Aikawa and Susan
Fong for their support on cellular and biochemical assays,
Ahmad Hashash on formulations, Jeremy Murray on
preliminary structural work, and Oncotest GmBH (Breisgrau,
Germany) for providing support on xenograft PKPD models.
REFERENCES
■
(
1) Santarpia, L.; Lippman, S. M.; El- Naggar, A. K. Targeting the
MAPK-RAS-RAF signaling pathway in cancer therapy. Expert Opin.
Ther. Targets 2012, 16, 103−119.
D
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ACS Medicinal Chemistry Letters
Letter
(
2) Davies, H.; Bignell, G. R.; Cox, C.; Stephens, P.; Edkins, S.;
Jochnowitz, N.; Parsons, W. H. Substitutied biaryl oxazoles,
imidazoles, and thiazoles as sodium channel blockers. Bioorg. Med.
Chem. Lett. 2010, 20, 5536−5540.
Clegg, S.; Teague, J.; Woffendin, H.; Garnett, M. J.; Bottomley, W.;
Davis, N.; Dicks, E.; Ewing, R.; Floyd, Y.; Gray, K.; Shall, S.; Hawes,
R.; Hughes, J.; Kosmidou, V.; Menzies, A.; Mould, C.; Parker, A.;
Stevens, C.; Watt, S.; Hooper, S.; Wilson, R.; Jayatilake, H.; Gusterson,
B. A.; Cooper, C.; Shipley, J.; Hargrave, D.; Pritchard-Jones, K.;
Maitland, N.; Chenevix-Trench, G.; Riggins, G. J.; Bigner, D. D.;
Palmieri, G.; Cossu, A.; Flanagan, A.; Nicholson, A.; Ho, J. W. C.;
Leueng, S. Y.; Yuen, S. T.; Weber, B. L.; Seigler, H. F.; Darrow, T. L.;
Paterson, H.; Marais, R.; Marshall, C. J.; Wooster, R.; Stratton, M. R.;
Futreal, P. A. Mutations of the B-RAF gene in human cancer. Nature
(15) Coordinates and structure factors have been deposited in the
Protein Data Bank (www.rcsb.org) with the accession code 5ct7.
(16) Zhang, J.; Yang, P. L.; Gray, N. S. Targeting cancer with small
molecule kinase inhibitors. Nat. Rev. Cancer 2009, 9, 28−39.
(17) Smith, A. L.; DeMorin, F. F.; Paras, N. A.; Huang, Q.; Petkus, J.
K.; Doherty, E. M.; Nixey, T.; Kim, J. L.; Whittington, D. A.; Epstein,
L. F.; Lee, M. R.; Rose, M. J.; Babij, C.; Fernando, M.; Hess, K.; Le, Q.;
Beltran, P.; Carnahan, J. Selective inhibitors of the mutant-B-RAF
Pathway: Discovery of a Potent and Orally Bioavailable Amino-
isoquinoline. J. Med. Chem. 2009, 52, 6189−6192.
(18) Kumar, R.; Crouthamel, M. C.; Rominger, D. H.; Gontarek, R.
R.; Tummino, P. J.; Levin, R. A.; King, A. G. Myelosupression and
kinase selectivity of multikinase angiogenesis inhibitors. Br. J. Cancer
2009, 101, 1717−1723.
2
(
002, 417, 949−954.
3) Martin-Liberal, J.; Larkin, J. New RAF kinase inhibitors in cancer
therapy. Expert Opin. Pharmacother. 2014, 15, 1235−1245.
4) Bollag, G.; Tsai, J.; Zhang, J.; Zhang, C.; Ibrahim, P.; Nolop, K.;
(
Hirth, P. Vemurafenib: the first drug approved for BRAF-mutant
cancer. Nat. Rev. Drug Discovery 2012, 11, 873−886.
(
5) Rheault, T. R.; Stellwagen, J. C.; Adjabeng, G. M.; Hornberger, K.
(19) A broad kinase survey was conducted on RAF265 and other
kinase inhibitors: Karaman, M. W.; Herrgard, S.; Treiber, D. K.;
Gallant, P.; Atteridge, C. E.; Campbell, B. T.; Chan, K. W.; Ciceri, P.;
Davis, M. I.; Edeen, P. T.; Faraoni, R.; Floyd, M.; Hunt, J. P.; Lockhart,
D. J.; Milanov, Z. V.; Morrison, M. J.; Pallares, G.; Patel, H. K.;
Pritchard, S.; Wodicka, L. M.; Zarrinkar, P. P. A quantitative analysis of
kinase inhibitor selectivity. Nat. Biotechnol. 2008, 26, 127−132.
R.; Petrov, K. G.; Waterson, A. G.; Dickerson, S. H.; Mook, R. A.;
Laquerre, S. G.; King, A. J.; Rossanese, O. W.; Arnone, M. R.;
Smitheman, K. N.; Kane-Carson, L. S.; Han, C.; Moorthy, G. S.; Moss,
K. G.; Uehling, D. E. Discovery of Dabrafenib: A selective inhibitor of
Raf kinases with antitumor activity against B-Raf driven tumors. ACS
Med. Chem. Lett. 2013, 4, 358−362.
(20) Melnick, J. S.; Janes, J.; Kim, S.; Chang, J. Y.; Sipes, D. G.;
(
6) Ramurthy, S.; Subramanian, S.; Aikawa, M.; Amiri, P.; Costales,
Gunderson, D.; Jarnes, L.; Matzen, J. T.; Garcia, M. E.; Hood, T. L.;
Beigi, R.; Cia, G.; Harig, R. A.; Asatryan, H.; Yan, S. F.; Zhou, Y.; Gu,
X. J.; Saadat, A.; Zhou, V.; King, F. J.; Shaw, C. M.; Su, A. I.; Downs,
R.; Gray, N. S.; Schultz, P. G.; Warmuth, M.; Caldwell, J. S. An
efficient rapid system for profiling the cellular activities of molecular
libraries. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 3153−3158.
A.; Dove, J.; Fong, S.; Jansen, J. M.; Levine, B.; Ma, S.; McBride, C. M.;
Michaelian, J.; Pick, T.; Poon, D. J.; Girish, S.; Shafer, C. M.; Stuart,
D.; Sung, L.; Renhowe, P. A. Design and Synthesis of Orally
Bioavailable Benzimidazoles as RAF kinasse inhibitors. J. Med. Chem.
2
(
008, 51, 7049−7052.
7) Subramanian, S.; Costales, A.; Williams, T.; Levine, B.; McBride,
(
21) Arnott, J. A.; Planey, S. L. The influence of lipophilicity in drug
discovery and design. Expert Opin. Drug Discovery 2012, 7, 863−875.
22) Novartis Pharmaceuticals. A Study to Evaluate RAF265, an Oral
C.; Poon, D.; Amiri, P.; Renhowe, P.; Shafer, C.; Stuart, D.; Verhagen,
J.; Ramurthy, S. Design and synthesis of orally bioavailable
benzimidazole reverse amides as pan-RAF kinase inhibitors. ACS
Med. Chem. Lett. 2014, 5, 989−992.
(
Drug Administered to Subjects With Locally Advanced or Metastatic
Melanoma. http://clinicaltrials.gov/show/NCT00304525 (NLM
Identifier: NCT00304525).
(
8) Wilhelm, S.; Carter, C.; Lynch, M.; Lowinger, T.; Dumas, J.;
Smith, R. A.; Schwartz, B.; Simantov, R.; Kelley, S. Discovery and
development of sorafenib: a multikinase inhibitor for treating cancer.
Nat. Rev. Drug Discovery 2006, 5, 835−844.
(
9) Tsai, J.; Lee, J. T.; Wang, W.; Zhang, J.; Cho, H.; Mamo, S.;
Bremer, R.; Gillette, S.; Kong, J.; Haass, N. K.; Sproesser, K.; Li, L.;
Smalley, K. S. M.; Fong, D.; Zhu, Y. L.; Marimuthu, A.; Nguyen, H.;
Lam, B.; Liu, J.; Cheung, I.; Rice, J.; Suzuki, Y.; Luu, C.; Settachatgul,
C.; Shellooe, R.; Cantwell, J.; Kim, S. H.; Schlessinger, J.; Zhange, K. Y.
J.; West, B. L.; Powell, B.; Habets, G.; Zhang, C.; Ibrahim, P. N.; Hirth,
P.; Artis, D. R.; Herlyn, M.; Bollag, G. Discovery of a selective inhibitor
or oncogenic B-Raf kinase with potent antimelanoma activity. Proc.
Natl. Acad. Sci. U. S. A. 2008, 105, 3041−3046.
(
10) Brown, S. A.; Rizzo, C. J. A “one-pot” phase transfer alkylation/
hydrolysis of o-nitrotrifluoroacetanilides. A convenient route to N-alkyl
-phenylenediamines. Synth. Commun. 1996, 26, 4065−4080.
11) McKillop, A.; Fiaud, J. C.; Hug, R. P. The use of phase- transfer
catalysis for the synthesis of phenol ethers. Tetrahedron 1974, 30,
379−1382.
12) Baldwin, J. J.; Kasinger, P. A.; Novello, F. C.; Sprague, J. M. 4-
0
(
1
(
Trifluoromethylimidazoles and 5-(4-pyridyl)-1,2,4-triazoles, new
classes of xanthine oxidase inhibitors. J. Med. Chem. 1975, 18, 895−
9
00.
(
13) An alternative process procedure has been described: Artman,
G.; Solovay, C. F.; Adams, C. M.; Diaz, B.; Dimitroff, M.; Ehara, T.;
Gu, D.; Ma, F.; Liu, D.; Miller, B. R.; Pick, T. E.; Poon, D. J.; Ryckman,
D.; Siesel, D. A.; Stillwell, B. S.; Swiftney, T.; van Dyck, J. P.; Zhang,
C.; Ji, N. One pot synthesis of aminobenzimidazoles using 2-chloro-
1
5
(
,2-dimethylimidazolium chloride (DMC). Tetrahedron Lett. 2010, 51,
319−5321.
14) Tyagarajan, S.; Chakravarty, P. K.; Zhou, B.; Fisher, M. H.;
Wyvratt, M. J.; Lyons, K.; Klatt, T.; Li, X.; Kumar, S.; Williams, B.;
Felix, J.; Priest, B. T.; Brochu, R. M.; Warren, V.; Smith, M.; Garcia,
M.; Kaczorowski, G. J.; Martin, W. J.; Abbadie, C.; McGowan, E.;
E
DOI: 10.1021/ml500526p
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX