J. Porter et al. / Bioorg. Med. Chem. Lett. 19 (2009) 2780–2784
2783
Table 5
SAR of imidazo[2.1.b]thiazole analogues
Cl
N
O
S
N
O
N
S
R
N
Compd
R
c-Met IC50
(nM)
MKN-45 IC50
(nM)
A549 IC50
(nM)
44
45
H
35
24
HN
1700
110
1710
90
N
N
46
9
HN
N
47
48
NH2
H
10
35
490
nd
580
nd
49
OH
15
3600
2810
Figure 2. Western blot of MKN-45 cells after treatment with compound 39
showing absence of p-Erk and p-Akt.
t-Boc
N
50
27
1946
110
N
features in the potent c-Met inhibitor PF-234106613) appeared to
enhance potency. Also noteable is the effect of the piperidinyl pyr-
azole group on the cell-based activity, as shown by comparison of
46 with the piperazine analogue 45.
t-Boc
N
N
51
19
147
450
N
In order to exert its cellular functions c-Met signals through
multiple downstream signaling pathways, including the mitogen
activated protein kinase (ERK1/2) and mediated signaling PI3K/
AKT pathways. The Western blot in Figure 2 shows that 39 inhib-
ited c-Met autophosphorylation in MKN-45 cells in a dose depen-
dent manner and, significantly, inhibition of phospho-AKT and
phospho-ERK1/2 was also observed.14 No activity was observed
for 39 against AKT and ERK 1/2 in a screen against a panel of 60
kinases.15
nd: no data.
Table 6
Non-sulphonylated 4-azaindoles analogues
R1
N
R2
In conclusion we have identified a novel series of 4-azaindole
inhibitors of c-Met kinase. Guided by an X-ray crystal structure
we have been able to rationalise the SAR and identified positions
where further optimisation would prove profitable.
N
Compd R1
R2
c-Met
IC50
(nM)
MKN-45
IC50
(nM)
A549
IC50
(nM)
References and notes
52
53
54
Benzyl
2-Nitro benzoyl
2-Nitro
H
H
H
i/a
12100
250
nd
nd
nd
nd
nd
nd
1. Yasui, H.; Imai, K. Anti-Cancer Agents Med. Chem. 2008, 8, 470; Alaoui-Jamali, M.
A. Biomed. Pharmacother. 2006, 60, 629; de Jonge, M. J. A.; Verweij, J. Eur. J.
Cancer 2006, 42, 1351.
2. Birchmeier, C.; Birchmeier, W.; Gherardi, E.; van de Woude, G. F. Nat. Rev. Mol.
Cell Biol. 2003, 4, 915.
3. Christensen, J. G.; Burrows, J.; Salgia, R. Cancer Lett. 2005, 225, 1; Ma, P. C.;
Maulik, G.; Christensen, J.; Salgia, R. Cancer Metastasis Rev. 2003, 22, 309.
4. Cui, J. J. Exp. Opin. Ther. Patents 2007, 17, 1035; Comoglio, S. G.; Giordano, S.;
Trusolino, L. Nat. Rev. Drug Disc. 2008, 7, 504.
5. IC50 values for inhibitors of c-Met were determined using an IMAP Time
Resolved Fluorescence Resonance Energy Transfer (TR-FRET) assay. 50 nM 6
His-tagged recombinant human c-Met residues 974-end (Millipore) was
incubated in 20 mM Tris, 10 mM MgCl2, 2.5 mM MnCl2, 0.01% Tween 20 and
phenylethyl
O
N
N
N
N
HN
N
55
56
57
19
1800
nd
1880
nd
N
O
N
HN
1040
33
N
2 mM DTT with 5
volume of 25 l for 60 min at ambient temperature. Inhibitors were tested at
10 concentrations starting from 20 M at a final concentration of 1% DMSO.
The reaction was stopped by addition of 50 l of IMAP Stop solution containing
lM ATP and 200 nM 5FAM-KKKSPGEYVNIGFG-NH2 in a total
t-Boc
l
N
O
N
l
l
N
3080
3280
N
60%Buffer A:40%Buffer B and a 1 in 400 dilution of beads and Terbium reagent.
Plates were read after an overnight incubation at 4 °C on an Analyst HT reader.
Reported IC50s are from a minimum of 2 experiments (n = 2). Data analysis was
carried out using a four parameter curve fit. The standard errors of the mean
were calculated and expressed as a percentage of the mean IC50. The average
for this value was 12%.
nd: no data.
6. Hopkins, C. R.; Cohen, N. Tetrahedron Lett. 2004, 45, 8087.
7. For example see: Graczyk, P. P.; Dimopoulos, P.; Khan, A.; Bhatia, G. S.; Farthing,
C. N. Patent application WO2008095944.; Ibrahim, P. N.; Artis, D. R.; Bremer, R.;
Mamo, S.; Nespi, M.; Zhang, C.; Zhang, J.; Zhu, Y-L.; Tsai, J.; Hirth, K-P.; Bollag,
G.; Spevak, W.; Cho, H.; Gillette, S. J.; Wu, G.; Zhu, H.; Shi, S. Patent application
WO2007002325.
c-Met and subsequent downstream signaling are consequences of
receptor overexpression. A549 cells are human derived non-small
cell lung cancer cells (NSCLC) and in contrast to MKN45 cells, c-
Met activation is dependent upon engagement with ligand-inde-
pendent c-Met phosphorylation11). In this assay12 addition of a sol-
ubilising group such as the piperidinyl pyrazole 39 (a group that
8. Crystallisation and solution of structure performed by Proteros Biostructures
GmbH,
Am
Klopferspitz
19,
D-82152,
Martinsried,
Germany,
been deposited with the PDB (pdb code 2wd1).