Identification of novel series of human CCR1 antagonists

Article abstract of DOI:10.1016/j.bmcl.2007.09.068

A hit-to-lead optimization process was carried out on the high throughput screening hit compound 1 resulting in the identification of several potent and selective CCR1 receptor antagonists. Compound 37 shows the best overall profile with IC₅₀ values of <100 nM in binding and functional assays.

Full text of DOI:10.1016/j.bmcl.2007.09.068

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry Letters 18 (2008) 2215–2221
Identification of novel series of human CCR1 antagonists
Yun Feng Xie,a, Ila Sircar,a Kirk Lake,a Mallareddy Komandla,a Kathleen Ligsay,a
Jian Li,b Kui Xu,b,à Jason Parise,b Lisa Schneider,b Dingqiu Huang,b Juping Liu,b
Naoki Sakurai,b,§ Miguel Barbosab,– and Rick Jackb,*
aDepartment of Chemistry, Tanabe Research Laboratories USA, Inc., 4540 Towne Centre Court, San Diego, CA 92121, USA
bDepartment of Biology, Tanabe Research Laboratories USA, Inc., 4540 Towne Centre Court, San Diego, CA 92121, USA
Received 14 June 2007; revised 19 September 2007; accepted 19 September 2007
Available online 25 September 2007
Abstract—A hit-to-lead optimization process was carried out on the high throughput screening hit compound 1 resulting in the iden-
tification of several potent and selective CCR1 receptor antagonists. Compound 37 shows the best overall profile with IC50 values of
<100 nM in binding and functional assays.
ꢀ 2008 Published by Elsevier Ltd.
Chemokines are a growing family of proteins that play
an important role in leukocyte activation and migra-
tion.1–3 They are divided into four subfamilies: CC,
CXC, XC, and CX3C defined by the position of the con-
served cysteine residues near the N terminus. The che-
mokines CCL3 (MIP-1a) and CCL5 (RANTES) bind
to their shared receptor CCR1, which is expressed on
a number of cell types including monocytes, macro-
phages, dendritic cells, and T cells. A substantial body
of evidence has linked the chemokine receptor CCR1
and its major ligands to the pathogenesis of chronic
inflammatory diseases including rheumatoid arthritis
(RA),4,5 multiple sclerosis (MS),6,7 and transplant rejec-
tion.8,9 The first clinical proof-of-concept in RA was ob-
tained with a small molecule CCR1 antagonist that
showed marked decrease in synovial inflammation and
trend toward a decrease in clinical disease activity after
2 weeks of treatment.10 Severe side effects were not re-
ported from these studies. These results illustrate the
therapeutic potential of small molecule CCR1 antago-
nists in these diseases, and thus make CCR1 an attrac-
tive target for drug discovery research. Here we report
our work directed toward the identification of novel
small molecule CCR1 antagonists.
Several chemotypes have been described as CCR1 antag-
onists: benzylpiperazines I (BX-471)9,11 and II,12 xan-
thene-9-carboxamides (III),13 4-hydroxypiperidines (IV
and VI),14,15 and hydroxyethylene peptide isosteres
(VII)16 (Chart 1). BX-471 and compound VI were ad-
vanced to the clinic for multiple sclerosis and rheumatoid
arthritis, respectively. To identify novel chemotypes we
screened a library of 4277 compounds using a fluorescent
calcium flux as measured by fluoresecent imaging plate
reader (FLIPR).17 The initial 12 screening hits were con-
firmed by a competitive receptor binding assay.18 The
hydroxypiperidine compound 1 emerged as the best hit
with moderate activity (IC50 < 6 lM; Fig. 1). Hit-to-lead
modification strategies were developed around com-
pound 1 to increase potency.
Keywords: Chemokine receptor 1; CCR1 antagonist.
*
Corresponding author. Tel.: +1 858 622 7022; fax: +1 858 558
0650; e-mail: rjack@trlusa.com
Present address: Genomics Institute of the Novartis Research
Foundation, 10675 John Jay Hopkins Drive, San Diego, CA
92121, USA.
Strategically, compound 1 was divided into four discrete
areas: hydrophobe 1 (right aromatic), amide functional-
ity, aliphatic linker, and hydrophobe 2 (4-hydroxy-4-
phenylpiperidine (Fig. 2)). Systematic structure–activity
relationship (SAR) studies were conducted in each por-
tion to improve the potency. Initial efforts were focused
on the hydrophobe 1 and the amide functionality. To
that end, 1-(3-aminopropyl)-4-(4-chlorophenyl)piperi-
à
Present address: Amylin, 9360 Towne Centre Drive, San Diego,
California 92121.
§
Present address: Mitsubishi Tanabe Pharma Corporation, 1000
Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa, 227-0033
Japan.
–
Present address: Johnson & Johnson Pharmaceutical Research &
Development, 3210 Merryfield Row San Diego, California 92121.
0960-894X/$ - see front matter ꢀ 2008 Published by Elsevier Ltd.
doi:10.1016/j.bmcl.2007.09.068

2216
Y. F. Xie et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2215–2221
O
OH
N
Cl
O
F
O
O
N
Ph
Ph
N
N
N
N
NHMe
Cl
Cl
NH
H
CN
OH
O
NH2
IV
VII
I (BX-471)
OH
O
N
Cl
Ph
Ph
F
N
N
NH
NH
NH
O
V
O
II
NH
Cl
OH
I-
O
CN
N
F
O
+
N
S
HN
Cl
III
VI
Chart 1. Structure of prototype CCR1 antagonists.
bipiperidine analogs 41–44 were synthesized from the
corresponding amine, (4-chlorophenyl)-40-methyl-1,40-
bipiperidin-4-ol20 (Scheme 3). The synthesis of the
corresponding 20-methyl analogs, 45 and 46, was accom-
plished in two steps starting from 2-methylpiperidin-4-
one as shown in Scheme 4. The enantiomerically pure
1,30-bipiperidin-4-ol analogs (47–52) were prepared by
starting with chiral 4-(4-chlorophenyl)-1,30-bipiperidin-
4-ol intermediate (Scheme 5). Compounds (53–55)
wherein the piperidine ring (A) was changed to pyrroli-
dine21 and azepine22 ring systems were prepared starting
from the requisite amines in a manner similar to com-
pounds in Scheme 2. Compounds 56 and 57 in which
the hydroxyl group in the piperidine ring (A) was re-
placed with CN group were prepared from the requisite
amine23 according to Schemes 1 and 2, respectively.
Compounds 58–69 were prepared by methods similar
to Scheme 2.
HO
H
N
N
Cl
O
Hit compound 1
IC50 (μM): 5.83 (Binding)
1.65 (FLIPR)
Figure 1. Structure of HTS hit.
Left aromatic
(Hydrophobe 2)
Linker region
Right aromatic
(Hydrophobe 1)
HO
H
N
N
The analogs prepared in this study were evaluated for
their inhibitory activity against 125I-MIP-1a binding to
human CCR118 and functional antagonist activity
(Ca2+ flux) in MIP-1a stimulated THP-1 cells.17 Ini-
tially, a small focused library was generated varying
the right hand aromatic of the hit compound 1, which
offered no improvement in activity. Replacement of
the amide group with other functionalities (e.g., urea,
thiourea, and reverse amides; data not shown) resulted
in compounds with significant loss in activity. Com-
pound 2, the sulfonamide analog of 1, showed about
3-fold improvement in activity which was the starting
point for detailed SAR studies. Table 1 lists all sulfon-
amide derivatives in the aminopropyl series. Compound
3, the 1-naphthyl analog of 2, retained similar potency.
O
Cl
Amide functionality
Figure 2. Hit-to-lead optimization strategy.
din-4-ol prepared in two steps19 was derivatized via
standard acylation reactions to provide amides and sul-
fonamides, 2–31 (Scheme 1). A small set of urea/thio-
urea compounds was prepared via the reaction of the
above amine with desired isocyanates and isothiocya-
nates, respectively (Scheme 1). Compounds 32–40 were
prepared from 4-(4-chlorophenyl)-1,40-bipiperidin-4-ol
by the treatment with requisite sulfonyl chlorides in a
similar fashion (Scheme 2). The 40-methyl substituted

Y. F. Xie et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2215–2221
2217
O
HO
HO
N
N
b
NH
a
O
Cl
Cl
X
HO
N
H
Ar
HO
N
NH2
N
c or d or e or f
Cl
R1
R2
Cl
;
X = CO; Ar =
R1
R2
X = CONH- and CSNH-; Ar =
X = SO2 (2- 31)
B
A
Scheme 1. Reagents and conditions: (a) N-(3-bromopropyl)phthalimide, Cs2CO3, KI, DMF, rt, 18 h; (b) H2NNH2, MeOH, rt, 18 h; (c) ArCOCl,
DIEA, CH2Cl2, rt, 1 h; (d) ArNCO, DIEA, CH2Cl2, rt, 18 h; (e) ArNCS, DIEA, CH2Cl2, rt, 18 h; (f) ArSO2Cl, DIEA, CH2Cl2, rt, 1 h.
HO
HO
O
O
A
N
n
A
B
NH
A
b
N
a
Et
B
R
R
O
S
HO
N
n
A
HO
N
O
c
B
N
n
NH
Ar
R
R
n = 1; 32-40
n = 1; 58-69
n = 0; 53-54
n = 2; 55
Scheme 2. Reagents and conditions: (a) ethyl 4-oxopiperidine-1-carboxylate, Na(OAc)3BH, CH2Cl2, rt, overnight; (b) H2NNH2, 50% aq KOH,
EtOH, reflux, 18 h; (c) ArSO2Cl, DIEA, CH2Cl2, rt, 1.5 h.
O
N S O
Ar
Me
N
HO
O
O
Me
N
B
HO
B
N
a, b
A
41-44
Cl
Cl
Scheme 3. Reagents and conditions: (a) 50% TFA in CH2Cl2, rt, 30 min; (b) ArSO2Cl, DIEA, CH2Cl2, rt, 1.5 h.
Me
O
Me
N
O
B
HO
O
S
Ar
O
S
B
A
N
N
a
b
O
B
O
Ar
N
H
Me
45, 46
Cl
Scheme 4. Reagents and conditions: (a) ArSO2Cl, DIEA, CH2Cl2, rt, 1.5 h; (b) 4-(4-chlorophenyl)piperidin-4-ol, Na(OAc)3BH, CH2Cl2, rt, 18 h.
The naphthyl moiety in 3 could favorably be replaced
with the phenyl (4) with a 2-fold improvement in po-
tency. The substitution on the phenyl ring was evaluated
next. Addition of halogens (5, 6, and 9) in the 2-position
of 4 maintained potency; halogens at the 4-position were
less favored (compare 8 and 10 vs 6 and 9). Similar ef-

2218
Y. F. Xie et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2215–2221
OH
B
OMs
HO
HO
c
a
b
B
N
A
Cl
N
A
B
NH
Cl
N
B
N
N
Boc
Boc
Ar
S
47-52
O
O
Scheme 5. Reagents and conditions: (a) MsCl, TEA, THF, 0 ꢁC, 3 h; (b) 4-(4-chlorophenyl)piperidin-4-ol, DMSO, 100 ꢁC, 18 h; (c) ArSO2Cl, DIEA,
CH2Cl2, rt, 2 h.
Table 1. SAR of substitution on the aryl moiety in the aminopropyl
series
(31) showed the best potency (IC50 values of <100 nM
in binding and Ca2+ flux assays) (Table 1).
O2
S
HO
Compounds in the 1,4-bipiperidine linker series (Table
2) were, in general, slightly less potent than the amino-
propyl linker series. Best activity was seen with the 2-
Cl (33) and 2-Br (37) substituted analogs, respectively.
From these results it was apparent that the SAR trend
in the aminopropyl series could be applied to the bipi-
peridine series and other variations to the bipiperidine
N
N
Ar
H
Cl
Compound
Ar
CCR1 bindinga
Ca2+ fluxb
IC50 (lM)
IC50 (lM)
2
2-Naphthyl
1-Naphthyl
Ph
1.15
0.68
0.30
0.14
0.11
0.38
0.80
0.58
0.91
0.15
0.43
0.25
9.4
0.52
0.18
0.09
0.17
0.04
0.10
0.37
0.08
0.21
0.03
0.12
0.05
2.2
3
4
Table 2. SAR of substitution on the aryl moiety in the 1,40-
bipiperidin-4-ol linker series
5
2-Br–Ph
2-Cl–Ph
6
7
3-Cl–Ph
4-Cl–Ph
O
HO
8
O
S
B
N
A N
Cl
9
2-F–Ph
4-F–Ph
Ar
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
CCR1 bindinga Ca2+ fluxb
2-Me–Ph
4-Me–Ph
2-CF3–Ph
4-CF3–Ph
2-OCF3–Ph
4-OCF3–Ph
4-OMe–Ph
2-Ph–Ph
Compound Ar
IC50 (lM)
IC50 (lM)
32
33
34
35
36
37
38
39
40
Ph
2-Cl–Ph
1.27
0.20
0.42
0.5
1.24
0.13
0.42
0.18
0.43
0.09
0.33
1.02
0.67
0.35
9.0
0.19
3.65
0.83
0.084
>30
0.07
0.385
0.23
0.11
0.35
0.36
0.28
2.46
1.34
0.03
0.10
0.04
2,6-DiCl–Ph
2-Me–Ph
2-Cl, 6-Me–Ph
2-Br–Ph
3.88
0.6
0.37
0.09
4-Ph–Ph
2-Th
3-Th
>30
0.16
0.57
0.24
0.35
0.51
0.41
0.54
1.85
0.78
0.08
0.36
0.09
2-Br, 4,6-DiF–Ph 1.12
2-Th
2,3,4-TriCl–Ph
0.97
3.6
2-(2-Th)–Ph
2-(3-Th)–Ph
2,3-DiCl–Ph
2,4-DiCl–Ph
2,5-DiCl–Ph
3,4-DiCl–Ph
3,5-DiCl–Ph
2,6-DiCl–Ph
2-Cl, 4-F–Ph
2-Cl, 6-Me–Ph
a Results shown are mean values of triplicate samples in a single
experiment.
b Results shown are the mean values of at least two independent
experiments.
Table 3. SAR of substitution on the B-ring of the 1,40-bipiperidin-4-ol
linker
R2
a Results shown are mean values of triplicate samples in a single
experiment.
b Results shown are the mean values of at least two independent
experiments.
R1
N
O
HO
N S O
Cl
Ar
Compound Ar
R1 R2 CCR1 bindinga Ca2+ fluxb
fects were observed with Me, CF3, OCF3, and Ph substi-
tutions at 2-position (11, 13, 15, and 18) versus 4-posi-
tion (12, 14, 16, and 19) of the phenyl ring (4),
respectively. The complete loss in potency of 19 impli-
cates limited space around that site. Replacement of
the phenyl in 4 by thienyl (Th) was tolerated; the 2-thi-
enyl analog 20 was slightly more potent than the 3-thie-
nyl analog 21. Compounds 22 and 23, the 2- and 3-
thienyl substituted phenyl analogs, retained potency
similar to the 2-biphenyl analog 18. Among the di-
substituted compounds, 2,6-diCl (29) and 2-Cl, 6-Me
IC50 (lM)
Me H 5.15
Me H 4.2
2-Cl, 6-Me–Ph Me H 3.57
IC50 (lM)
41
42
43
44
45
46
2-Cl–Ph
2,6-DiCl–Ph
2.26
4.65
2.26
7.33
0.28
0.12
2-Th
2-Cl–Ph
2-Br–Ph
Me H >10
H
H
Me 0.32
Me 0.22
a Results shown are mean values of triplicate samples in a single
experiment.
b Results shown are the mean values of at least two independent
experiment.

Y. F. Xie et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2215–2221
2219
Table 4. SAR of substitution on the aryl moiety in the 1,30-
bipiperidin-4-ol linker series
Table 6. SAR of substitution on the left aromatic in the 1,40-
bipiperidin-4-ol linker series
HO
3'
O
S
O
HO
B
N
A
N
N
O
N
S
R
Cl
O
Ar
Cl
Compound
R
CCR1 bindinga
Ca2+ fluxb
Compound 30-Enantiomer Ar
CCR1 bindinga Ca2+ fluxb
IC50 (lM)
IC50 (lM)
IC50 (lM)
IC50 (lM)
58
59
60
61
62
63
64
65
66
67
68
69
4-F
4-Br
1.17
0.44
7.0
1.25
0.18
6.21
0.59
0.18
0.61
2.55
>10
>10
>10
7.98
>10
47
48
R
S
2-Cl,
0.39
0.27
3-Cl
6-Me–Ph
2-Cl,
6-Me–Ph
3-Cl, 4-F
3, 4-DiCl
3-F, 4-Cl
3,4,5-TriF
4-t-Bu
4-Ph
0.51
0.89
0.43
1.33
>10
>10
>10
>10
>10
0.43
0.48
49
50
51
52
R
S
2-Cl–Ph 1.98
2-Cl–Ph 1.9
2-Br–Ph 1.4
2-Br–Ph 0.46
1.29
2.04
1.4
R
S
1.3
4-OMe
4-SMe
4-OPh
a Results shown are mean values of triplicate samples in a single
experiment.
b Results shown are the mean values of at least two independent
experiments.
a Results shown are mean values of triplicate samples in a single
experiment.
b Results shown are the mean values of at least two independent
experiments.
Table 5. Effects of hydroxypiperidine ring size modifications
O
S
R1
HO
O
N
N
Cl
(47 and 48) and significant decrease was noted with
the 2-Cl (49 and 50) and 2-Br (51 and 52) analogs.
One possible explanation could be that the rotation of
the phenyl group was more hindered with 2,6-di-substi-
tution, and the molecule was locked in one conforma-
tion that resulted in tight binding with the receptor.
R2
Compound
N
R1
R2
CCR1 bindinga
Ca2+ fluxb
IC50 (lM)
IC50 (lM)
33
53
54
55
1
0
0
2
Cl
Cl
Cl
Cl
H
0.201
>30
>30
0.13
>10
>10
0.13
H
Interesting results were observed with the compounds
wherein the piperidine (A) ring size was changed. The
potency of 53 and 54 (pyrrolidine analogs of 33 and
36; Table 5) was severely compromised whereas only
marginal loss in potency was observed with 55 (azipine
analog of 33).
Me
H
0.40
a Results shown are mean values of triplicate samples in a single
experiment.
b Results shown are the mean values of at least two independent
experiments.
It is conceivable that the H-bond required for activity
could not be realized in 53 and 54 due to the shorter dis-
tance between the ring nitrogen and the polar group
(OH). By contrast, the slightly longer distance in 55
may still fall within the range of H-bond contact with
the receptor. Similar observations were reported in the
haloperidol SAR studies.22 The importance of the
–OH group was also recognized from the 5-fold reduction
in potency observed with the –CN analogs 56 and 57
(IC50 binding: 0.6 and 1 lM) (Scheme 6) in comparison
to 6 and 33 (IC50 binding: 0.11 and 0.2 lM), respec-
tively. The substitution on the left aromatic ring was
investigated next (Table 6). Compound 58, the 4-F ana-
log of 33 showed 6-fold reduced potency whereas
marginal potency loss was observed with the corre-
linker were undertaken. Addition of a small group, for
example, a methyl in the 40-position of the piperidine
ring B (Table 3), was detrimental (compare 41–44 with
33, 34, 36, and 39) whereas similar substitution at the
20-position retained potency (45 and 46 vs 33 and 37)
suggesting the importance of the conformation of the
molecule for binding to the receptor.
A small number of enantiomerically pure compounds
were prepared in the 1,30-bipiperidine linker series incor-
porating the best aryl sulfonamide moieties (Table 4).
However, no discrimination between R- and S-enantio-
mers was observed with these analogs. The potency was
maintained with the 2-Cl, 6-Me di-substituted analogs
Cl
O
Cl
O
O
NC
O
NC
NC
a-c
NH
S
a, b, f
N
S
N
N
HN
Scheme 2
Scheme 1
57
56
Cl
Cl
Cl
Scheme 6. Reagents and conditions: see Schemes 1 and 2.

2220
Y. F. Xie et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2215–2221
Table 7. Chemotaxis activity of selected compounds
11. Liang, M.; Mallari, C.; Rosser, M.; Ng, H. P.; May, K.;
Monahan, S., et al. J. Biol. Chem. 2000, 175, 19000.
12. Revesz, L.; Bollbuck, B.; Buhl, T.; Eder, J.; Esser, R.;
Feifel, R.; Heng, R.; Hiestand, P., et al. Bioorg. Med.
Chem. Lett. 2005, 15, 5160, Novartis.
13. Naya, A.; Sagara, Y.; Ohwaki, K.; Saeki, T.; Ichikawa,
D.; Iwasawa, Y.; Noguchi, K.; Ohtake, N. J. Med. Chem.
2001, 44, 1429.
Compound
Chemotaxisa
IC50 (lM)
18
22
33
37
0.151
0.296
0.183
0.042
a Results shown are the mean values of at least two independent
experiments.
14. Ng, H. P.; May, K.; Bauman, J. G.; Ghannam, A.; Islam,
I.; Liang, M.; Horuk, R.; Hesselgesser, J.; Snider, R. M.;
Perez, H. D.; Morrissey, M. M. J. Med. Chem. 1999, 42,
4680.
15. Hesselgesser, J.; Ng, H. P.; Liang, M.; Zheng, W.; May,
K.; Bauman, J. G.; Monahan, S.; Islam, I.; Wei, G. P.;
Ghannam, A.; Taub, D. D.; Rosser, M.; Snider, R. M.;
Morrissey, M. M.; Perez, H. D.; Horuk, R. J. Biol. Chem.
1998, 273, 15687.
16. Kath, J. C.; Bressette, W. H.; Brown, M. F.; Conklyn, M.;
DiRico, A. P.; Dorff, P.; Gladue, R.; Lillie, B. M.; Lira, P.
D.; Mairs, E. N.; Martin, W. H.; McElroy, E. B.;
McGlynn, M. A.; Paradis, T. J.; Poss, C. S.; Stock, I.
A.; Tylaska, L. A.; Zheng, D. Bioorg. Med. Chem. Lett.
2004, 14, 2169.
sponding 4-Br analog (59). Moving the chloro group to
the 3-position of the phenyl ring (60) was detrimental;
however addition of either a fluorine (61) or a chlorine
(62) at the 4-position in 60 recovered 8- to 14-fold activ-
ity. Compound 63, where the positions of the halogens
were switched, retained comparable potency (63 vs 61)
suggesting the importance of 4-halogen on the phenyl
ring. By contrast, replacement of the 4-chloro with the
bulky t-Bu (65) and phenyl (66) groups resulted in total
loss of affinity, suggesting a space restriction around this
site. All other substituents (e.g., OMe, SMe, and OPh)
led to inactive compounds. Some of the potency
improvement could be lipophilicity driven.
17. THP-1 cells in RPMI-1640 were adjusted to 2 · 106/ml,
mixed 1:1 with Calcium Assay Kit buffer (Molecular
Devices, Sunnyvale, CA), and incubated for 30 min at
37 ꢁC in the presence of 2.5 mM probenicid (Sigma). Dye-
loaded cells were then collected by centrifugation at
1000 rpm for 5 min, resuspended in assay buffer (RPMI-
1640 containing 0.1% BSA), and seeded at 1.5 · 105/well
on poly-D-lysine-coated 96-well plates (Molecular
Devices) with or without test compounds. The plates were
centrifuged at 1000 rpm for 5 min. After stimulation with
5 nM human MIP-1a, changes in intracellular free Ca2+
concentration were measured using FLIPR (Molecular
Devices).
18. THP-1 cells expressing CCR1 were harvested and washed
once with PBS. Cells (5 · 106/ml) were mixed with test
compound or vehicle and 50 pM human [125I]MIP-1a in a
96-well tissue culture plate in a total volume of 120 ll of
binding buffer which contained 50 mM Hepes, pH 7.4,
5 mM MgCl2, 1 mM CaCl2, and 0.5% BSA (Hepes–BSA).
The mixture was incubated at room temperature for
90 min and transferred to 96-well glass fiber filter plate
pre-coated with 0.5% polyethyleneimine (PEI). Cells were
separated by vacuum aspiration and washed twice with
Hepes–BSA containing 0.5 M NaCl. Radioactivity was
measured on TopCount plate reader with 40 ll Microscint
40 scintillation fluid. Non-specific binding was determined
in the presence of 150 nM unlabeled human MIP-1a.
19. Diurno, M. V.; Mazzoni, O.; Capasso, F.; Izzo, A. A.;
Bolognese, A. Farmaco 1997, 52, 237.
Receptor selectivity against CCR2, CCR3, CCR4, and
CCR5 (>100-fold) was confirmed with selected com-
pounds in Table 7. Several analogs retained potency to
inhibit CCL3-induced chemotaxis (Table 7).24 Com-
pound 37 showed the best overall profile.
In summary, hit-to-lead optimization on an in-house
hit generated several novel, potent, and selective
human CCR1 receptor antagonists. However, these
compounds showed weak affinity for the mouse recep-
tor. Further SAR development was discontinued
because of other series of actives with improved profile
were identified.25
References and notes
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Y. F. Xie et al. / Bioorg. Med. Chem. Lett. 18 (2008) 2215–2221
2221
30 min at 37 ꢁC and loaded in the wells on the top of a
5 lm polycarbonate filter in a 96-well Boyden chamber
(NeuroProbe), in which 0.5 nM human MIP-1a with or
without compounds had been added to the corresponding
wells beneath the filter. The sealed chamber was incubated
for 2 h at 37 ꢁC. Non-migrated cells on top of the filter
were removed by wiping. The filter was reversed and read
at 485/530 nm emission/excitation wavelengths with Flex-
Station II (Molecular Devices).
25. Yun Feng Xie et al. Unpublished results.