Discovery of a new potent bisamide FMS kinase inhibitor

Article abstract of DOI:10.1016/j.bmcl.2010.04.088

FMS is a type III receptor tyrosine kinase that binds to the macrophage or monocyte colony stimulating factor (M-CSF or CSF-1). Signal transduction through that binding results in survival, proliferation, and differentiation of monocyte/macrophage lineage. In this study, we report the discovery of a new potent inhibitor of FMS kinase. The synthesized pyrrolo[3,2-c]pyridine derivative (compound 1) was initially tested at a single concentration of 1 μM against 47 different kinases. At this concentration, the% inhibitions of the enzymatic activities of FMS and KDR kinases were 90% and 71%, respectively, while the inhibition in activity was less than 58% for all of the other kinases. For compound 1, the IC₅₀ values against FMS and KDR were 96 and 1058 nM, respectively. So, compound 1 was found to be 11 times more selective for FMS kinase than KDR kinase. Compound 1 can be used as a promising lead for the development of new selective inhibitors of FMS kinase, which can be used as useful therapeutic tools for treatment of several inflammatory and cancer disorders.

Full text of DOI:10.1016/j.bmcl.2010.04.088

Bioorganic & Medicinal Chemistry Letters 20 (2010) 3216–3218
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Discovery of a new potent bisamide FMS kinase inhibitor
Mohammed I. El-Gamal a,b, Myung-Ho Jung a, Chang-Hyun Oh a,b,
*
a Biomaterials Center, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea
b Department of Biomolecular Science, University of Science and Technology, 113 Gwahangno, Yuseong-gu, Daejeon 305-333, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 January 2010
Revised 8 April 2010
Accepted 20 April 2010
Available online 24 April 2010
FMS is a type III receptor tyrosine kinase that binds to the macrophage or monocyte colony stimulating
factor (M-CSF or CSF-1). Signal transduction through that binding results in survival, proliferation, and
differentiation of monocyte/macrophage lineage. In this study, we report the discovery of a new potent
inhibitor of FMS kinase. The synthesized pyrrolo[3,2-c]pyridine derivative (compound 1) was initially
tested at a single concentration of 1 lM against 47 different kinases. At this concentration, the% inhibi-
tions of the enzymatic activities of FMS and KDR kinases were 90% and 71%, respectively, while the inhi-
bition in activity was less than 58% for all of the other kinases. For compound 1, the IC50 values against
FMS and KDR were 96 and 1058 nM, respectively. So, compound 1 was found to be 11 times more selec-
tive for FMS kinase than KDR kinase. Compound 1 can be used as a promising lead for the development of
new selective inhibitors of FMS kinase, which can be used as useful therapeutic tools for treatment of sev-
eral inflammatory and cancer disorders.
Keywords:
FMS
KDR
Tyrosine kinase
Kinase inhibitor
Antiinflammatory
Cancer
Selectivity
Bisamide
Ó 2010 Published by Elsevier Ltd.
The macrophage or monocyte colony stimulating factor (M-CSF
or CSF-1) is the primary growth factor for the macrophage lineage.1
It interacts with the cells through its specific trans-membrane
receptor FMS (also known as CSF-1R)—a type III receptor tyrosine
kinase.1,2 Signal transduction through the CSF-1/FMS ligand–
receptor complex results in survival, proliferation, and differentia-
tion of cells of the monocyte/macrophage lineage.2 Over-expres-
sion of CSF-1 and/or FMS has been implicated in a number of
disease states such as the growth of metastasis of particular types
of cancer,3 in promoting osteoclast proliferation in bone osteoly-
sis,4 in inflammatory disorders such as rheumatoid arthritis,5 ath-
erosclerosis,6 and Crohn’s disease,7 and in renal allograft rejection.8
In addition, the expression of FMS in breast cancer has been linked
to poor survivability and increased tumor size, where presumably
the receptor is involved in local invasion and metastasis.9–11
Tumor associated macrophages play a major role in the micro-
tumor environment.12,13
Ki20227 is a urea type c-FMS tyrosine kinase inhibitor that has
been reported to suppress osteoclast differentiation and osteolytic
bone destruction in a bone metastasis model.17 Imatinib mesylate,
an arylamide derivative, has been recently reported to suppress
bone metastases of breast cancer by inhibiting osteoclasts differen-
tiation through blockade of c-FMS signals.18 A number of reports
have recently highlighted arylamides derivatives as potent FMS
inhibitors.19–23 Herein, we report the discovery of a potent FMS ki-
nase inhibitor 1 with bisamide moieties (Fig. 1). The synthetic and
screening protocols for this compound are illustrated in details.
The kinase inhibitory activity of the synthesized compound was
tested over 47 different kinases, and it showed selectivity for
FMS kinase.
Synthesis of the target compound 1 was achieved according to
the sequence illustrated in Scheme 1. 7-Hydroxy-1H-pyrrolo[2,3-
b]pyridinium 3-chloroperoxybenzoate (3) was prepared by react-
ing 1H-pyrrolo[2,3-b]pyridine (2) with 3-chloroperoxybenzoic
The role of CSF-1-dependent macrophage proliferation has been
evaluated by various animal studies.14,15 CSF-1-deficient mice were
reported to be resistant to collagen-induced arthritis (CIA). In a CIA
model, CSF-1 was shown to increase the severity of the disease
while a neutralizing anti-CSF-1 antibody had the opposite effect.
A monoclonal antibody to CSF-1 developed by Pfizer, PD-
0360324, has recently entered phase 1 clinical trials for treatment
of rheumatoid arthritis.16
O
N
N
H
CF3
HN
O
N
N
O
1
* Corresponding author. Tel.: +82 2 958 5160; fax: +82 2 958 5189.
E-mail address: choh@kist.re.kr (C.-H. Oh).
Figure 1. Structure of compound 1.
0960-894X/$ - see front matter Ó 2010 Published by Elsevier Ltd.
doi:10.1016/j.bmcl.2010.04.088

M. I. El-Gamal et al. / Bioorg. Med. Chem. Lett. 20 (2010) 3216–3218
3217
O
O
ii
iii
i
O
N
N
N
H
N
N
N
O
+
+
-
H
H
OH
Cl
2
4
3
N
Cl
N
NO2
N
iv
v
NO2
HN
O
N
H2N
HCl
N
H
N
5
6
7
O
N
N
N
H
NH2
vii
vi
CF3
HN
O
HN
O
N
N
N
O
8
1
Scheme 1. Reagents and conditions: (i) 3-chloroperoxybenzoic acid, DME/heptanes (1:2), 81%; (ii) K2CO3, H2O, CHCl3, 43%; (iii) CH3SO2Cl, DMF, 65 °C, 59%; (iv) m-
nitroaniline, 180 °C, 10%; (v) benzoyl chloride, diisopropylamine, CH3CN, 15%; (vi) Pd/C, H2, THF, 32%; (vii) 3-(trifluoromethyl)-4-morpholinobenzoic acid, HOBt, EDCI, TEA,
DMF, 80 °C, 16%.
acid.24,25 Compound 3 was converted into the N-oxide compound 4
Table 1
Percentages of enzymatic inhibitions exerted by compound 128 on 47 kinases
by reaction with potassium carbonate.24,25 4-Chloro-1H-pyrrol-
% Inhibitiona–c
o[2,3-b]pyridine (5) was prepared by heating 4 with methanesulfo-
nyl chloride in dry DMF. Compound 6 was prepared according to
the method described by Girgis et al.26 Heating 5 with m-nitroan-
iline led to nucleophilic displacement of the 4-chloro group by the
m-nitroaniline amino group, followed by rearrangement of the
resulting secondary amine to give the hydrochloride salt of 4-ami-
no-1-(3-nitrophenyl)-1H-pyrrolo[3,2-c]pyridine (6), albeit in low
yield. The amide derivative 7 was obtained by reaction of the ami-
no group of 6 with benzoyl chloride in the presence of diisopropyl-
amine as a base. Reduction of the nitro group of 7 using Pd–C/H2
gave the corresponding amino compound 8. The bisamide target
compound 1 was obtained by condensation with 3-(trifluoro-
methyl)-4-morpholinobenzoic acid using HOBt/EDCI/TEA.
The screening results of the target compound 1 over 47 differ-
ent kinases have revealed that the inhibitory activity of the com-
pound was not exhibited over most of the tested kinases, while
high inhibitory activity was selectively shown at FMS kinase only
(Table 1).27
Kinase enzyme
ABL1
ALK
41
11
21
7
À1
À12
8
À8
À2
10
À18
1
9
6
16
90
44
4
Aurora A
BTK
CaMKI
CDK2/cyclinE
CDK5/p25
CHK1
c-Kit (D816V)
c-SRC
DMPK
EGFR (T790M)
EPHA1
FGFR1
FLT3 (D835Y)
FMS
FYN
GSK3b
HIPK2
9
IGF-1R
IKKb
IR
10
23
2
JAK3
17
À1
71
33
À9
12
À16
À1
À10
7
JNK1
KDR
LCK
a1
The compound was tested initially at a single dose concentra-
tion of 1 lM. At this concentration, 90% inhibition of the enzymatic
MAPK1
MEK1
MET
MLK1
mTOR
P70S6K
PAK2
PDK1
PIM1
activity of FMS kinase was observed. It also inhibited the enzy-
matic activity of KDR kinase by 71%. While the inhibition in activity
was less than 58% in all of the other kinases, it was in the range of
30–57% in four kinases only (ABL1, FYN, LCK, and RET), and in the
range of 20–30% in another four kinases only (Aurora A, IKKb,
PYK2, and SAPK2a).
Compound 1 was further tested over FMS and KDR kinases in
order to determine its IC50, where a 10-doses IC50 mode with three-
fold serial dilutions starting at 2 lM concentration was applied. Ta-
2
À1
10
16
18
À5
4
PKA
PKB
a
PKCa
PLK1
ble 2 illustrates the IC50 values of compound 1 over FMS and KDR
kinases. Compound 1 was found to be 11 times more selective for
FMS kinase than KDR kinase.
The selectivity of compound 1 to FMS may be attributed to in-
creased bulkness around the pyrrolo[3,2-c]pyridine moiety. Com-
pound 1 includes two arylamide functionalities. This increase in
bulkness is seemed to hinder the fitting of the compound to the
binding sites of most of other kinases and to exclude it from their
binding pockets. The difference in geometry between the binding
PYK2
RET
23
57
3
19
8
25
6
14
ROCK1
ROS/ROS1
RSK1
SAPK2a
SYK
TEC (activated)
a
b
c
Test compound was used in a single dose concentration of 1 lM.
100% Activity refers to enzyme activity in negative control (DMSO).
% Inhibition was calculated by subtracting% activity from 100.

3218
M. I. El-Gamal et al. / Bioorg. Med. Chem. Lett. 20 (2010) 3216–3218
14. Campbell, I. K.; Rich, M. J.; Bischof, R. J.; Hamilton, J. A. J. Leukocyte Biol. 2000,
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IC50 of compound 1 over FMS and KDR kinases
15. Cook, A. D.; Braine, E. L.; Campbell, I. K.; Rich, M. J.; Hamilton, J. A. Arthritis Res.
2001, 3, 293.
Kinase enzyme
IC50 (nM)
16. Dose-escalating multiple dose study of PD-0360324 in combination with
methotrexate in patients with rheumatoid arthritis. ClinicalTrials.gov Identifier
NCT00550355.
FMS
KDR
96
1058
17. Ohno, H.; Kubo, K.; Murooka, H.; Kobayashi, Y.; Nishitoba, T.; Shibuya, M.;
Yoneda, T.; Isoe, T. Mol. Cancer Ther. 2006, 5, 2634.
18. Hiraga, T.; Nakamura, H. Int. J. Cancer 2009, 124, 215.
pocket of FMS tyrosine kinase and other kinases may enable the
selectivity of compound 1 for FMS. Moreover, the presence of
two hydrogen bond donors and many hydrogen bond acceptors
may enhance the selectivity of the compound for FMS kinase.
In conclusion, a new potent inhibitor for FMS kinase has been
synthesized and can be used as a promising lead for the develop-
ment of new selective inhibitors of FMS kinase, which can be used
as useful therapeutic tools for treatment of several inflammatory
and cancer disorders.
19. Patch, R. J.; Brandt, B. M.; Asgari, D.; Baindur, N.; Chadha, N. K.; Georgiadis, T.;
Cheung, W. S.; Petrounia, I. P.; Chaikin, M. A.; Player, M. R. Bioorg. Med. Chem.
Lett. 2007, 17, 6070.
20. Illig, C. R.; Chen, J.; Wall, M. J.; Wilson, K. J.; Ballentine, S. K.; Rudolph, J. M.;
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J.; Chaikin, M. A.; Manthey, C. L.; Player, M. R.; Tomczuk, B. E.; Meegalla, S. K.
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Acknowledgment
23. Burns, C. J.; Harte, M. F.; Bu, X.; Fantino, E.; Giarrusso, M.; Joffe, M.; Kurek, M.;
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We are grateful to Korea Institute of Science and Technology
(KIST) for financial support.
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