K. Ikegashira et al.
Bioorganic&MedicinalChemistryLettersxxx(xxxx)xxx–xxx
Table 2
Pharmacokinetic Parameters of Rat and Monkey for (R)-4a, (S)-8b, and 8d.a
Compd
Rat
Monkey
PO 3 mg/kg
Cmax μM
IV 1 mg/kg
CL L/hr/kg
IV 1 mg/kg
AUC μM*h
BA %
T1/2 hr
Vd L/kg
MRT hr
CL L/hr/kg
T1/2 hr
Vd L/kg
MRT hr
(R)-4a
0.74
0.49
0.27
4.15
2.22
1.63
75.8
85.1
115.5
1.09
2.23
3.79
1.10
1.62
0.91
1.51
3.27
3.46
1.37
1.46
0.91
2.64
0.67
0.46
0.26
13.4
1.60
0.76
5.00
0.56
0.28
7.50
1.20
(S)-8b JTE-952
8d
a
The animals used in the studies were male Sprague-Dawley rats (n = 2) and Cynomolgus monkeys (n = 2). For details, see the Supporting Information.
(S)-8b, which is JTE-952, would be the most promising clinical can-
didate from these results. We are submitting reports that describe the
therapeutic potential of JTE-952 in detail.
Table 3
The values of calculated log P and basic pKa for 5b, 5e–h.a
We had designed and synthesized an azetidine series in order to
obtain a highly selective CSF-1R inhibitor as a Type II kinase inhibitor.
In fact, we tried to obtain the crystal structure and we also evaluated a
kinase panel assay to confirm kinase selectivity.
Compd
Calc. log P
Calc. basic pKa
5b
5e
5f
4.00
3.93
2.89
2.89
3.05
7.75
6.29
7.56
7.56
5.57
We obtained the X-ray co-crystal structure of JTE-952 with CSF-1R
protein, which was reported in our previous report.13,16 JTE-952 bound
to the protein in the DFG-out state. As a result, we confirmed JTE-952 is
a typical Type II kinase inhibitor; therefore we predicted JTE-952 has
high kinase-selectivity.
5g
5h
a
The values were calculated by using MarvinSketch 16.1.18.0 (ChemAxon.
Ltd.).
To confirm actual kinase-selectivity of JTE-952, we conducted a
kinase panel assay of 51 human kinases at 1 μM (Millipore
KinaseProfiler™ Assay Service) for JTE-952. The results showed high
kinase selectivity (Table 4). Against 50 kinases, JTE-952 showed no
inhibition except for TrkA (IC50 = 261 nM) whereas the CSF1R
IC50 = 13 nM.
with conjugated metabolism. Actually, the phosphate conjugation with
terminal hydroxyl group was detected as the major metabolite from the
metabolite search experoments for (S)-8b (JTE-952) (data not shown).
Also, the phosphate conjugation cannot be produced by liver S9 and
there is a possibility that the conjugated metabolic activities differs
between the enantiomers. Therefore, we considered that in vivo efficacy
and persistence effect for the enantiomers made differences because of
the differences of the cojugated metabolic activities.
In conclusion, we have described the optimization of azetidine
scaffold13 leaded to a clinical candidate JTE-952, which showed high
cellular potency and in vivo efficacy in mice. Also, JTE-952 is expected
to show promising pharmacokinetic in human because of good PK
properties in monkey as well as rat. It was also shown to effectively
reduce clinical scores in the mouse CIA model as the pathological an-
imal model for RA. Furthermore, JTE-952 as a Type-II kinase inhibitor
showed high kinase selectivity. From these results, JTE-952 seems to be
a clinical candidate. Further pharmacological data of JTE-952 for
clinical tests will be reported in due course.
Since (R)-4a, (S)-8b, and 8d showed sufficient persistence in vivo
effect, these neutral compounds were expected as clinical candidates.
Furthermore, PK properties of these compounds were investigated in
order to predict pharmacokinetics in human, as shown in Table 2. In
rat, the bioavailability of these compounds were equally good, although
the oral exposure of (R)-4a was the highest (Cmax = 0.74 μM,
AUC = 4.15 μM*h) at 3 mg/kg PO. On the other hand, PK values in
monkey differed from the case of rat. (S)-8b exhibited the best profiles
for the pathological animal model, which were T1/2, Vd, and MRT (T1/
2 = 13.4, Vd = 5.00, MRT = 7.5) at 1 mg/kg i.v. as indexes of con-
tinuity. Consequently, (S)-8b was thought to be the most promising
compound.
Acknowledgments
We thank Mr. Eita Nagao for analytical support, and Mr. Naofumi
Uesato, Ms. Reina Kakefuda, and Dr. Takayuki Yamaguchi for running
the biological assays. We also acknowledge Dr. Tsuyoshi Adachi, Dr.
Satoki Doi, Dr. Tetsuo Yamashita, and Dr. Michiko Aoki for assistance
with the synchrotron data collection. We are grateful to Mr. Tatsuya
Matsumoto, Mr. Takuya Matsuo, Dr. Naoki Ogawa, and Dr. Atsushi
Hagiwara for support.
Next, we evaluated the therapeutic potential of compound (S)-8b
using the mouse model of collagen-induced arthritis (CIA model),
which is the pathological model for RA. Consequently, oral once-daily
dosing of 3 mg/kg reduced the overall progression of the clinical score,
including inflammation and bone erosion. Therefore, we expected that
Table 4
The results of 51 kinase profiler for JTE-952.a
IC50
Kinases
261 nM
TrkA
Abl, Aurora-A, CDK1/cyclinB, CDK2/cyclinA, CHK1, CK2, cKit, CSK, c-RAF, cSRC, EGFR, FGFR1, FGFR3, Flt1, Flt3, Fyn, GSK3β, IGF-1R, IKKβ, IR, JNK1α1,
JNK2α2, JNK3, KDR, Lck, Lyn, MAPK2, MAPKAP-K2, MEK1, Met, MSK1, p70S6K, PDGFRα, PDGFRβ, PDK1, PKA, PKBα, PKCα, PKCβ, PKCγ, PKCζ, Plk1, ROCK-II,
SAPK2a, SAPK2b, SAPK3, SGK, Syk, Tie2, ZAP-70
a
The effect of JTE-952 at a concentration of 1 µM was evaluated by using Millipore KinaseProfiler™ Assay Service (Millipore Co., USA).
4