3930
K. Park et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3927–3931
amides, 17c and 17f, provided excellent selectivity over
both MMP-2 and MMP-9, while amide 17e bearing an
ether tail was far less selective. Amides 17h–17j, bearing
amine and alcohol tails, were less than 100-fold selective
over MMP-2 but retained significant selectivity over
MMP-9. Compound 17d is the most potent alkyl amide
analog in Raw cells (IC50 = 60 nM) but only diol 17j had
moderate potency in both Raw cells and HWB. Aryl
and heteroaryl amides, 17k–17p, are in general more
potent in the TACE FRET assay than the alkyl amides.
The unsubstituted benzamide 17k and 4-methylbenza-
mide derivative 17o are both 50-fold selective for TACE
over MMP-2 and MMP-13, with greater than 400-fold
selectivity over MMP-9. In contrast, the ortho-substitut-
ed benzamides 17l and 17n are less than 20-fold selective
over MMP-2 and MMP-13. Pyridyl amide 17m is slight-
ly less potent than 17k against TACE and slightly more
potent than 17k against MMPs-2, -9, and -13. Amides
17m and 17p show excellent activity in Raw cells, with
IC50s of 30 and 70 nM, respectively. In the case of pyr-
idyl amide 17m the potent cellular activity carries over
to activity in HWB, providing the most active analog
of this series in this assay, 2-fold better than the more
basic picolyl analog 17a. However, as for butyl amide
17d, thienyl amide 17p is dramatically less active in
HWB than in Raw cells. Analysis of differences in
clogP, permeability, and protein binding does not
provide an adequate explanation for the discrepancy
between activity in Raw cells and HWB for most
analogs.
clearance (26 mL/min/kg), AUC0–inf (3343 ng h/mL),
and volume of distribution (0.7 L/kg).
In summary, we have explored the effect of variations
in the P1 moiety on the potency, selectivity, and cell
activity of a series of butynyloxyphenyl b-sulfone
piperidine hydroxamic acid TACE inhibitors. All of
these compounds were found to be potent inhibitors
of TACE in an isolated enzyme assay and several per-
formed well in cell-based assays in Raw cells and in
human whole blood (HWB). In particular, compound
17s is a 1.5 nM inhibitor of TACE that possesses
greater than 100-fold selectivity over MMP-1, -2, -7,
-8, -9, -13, and -14, as well as good activity
(IC50 = 1.5 lM) in HWB. Furthermore, in vivo oral
activity of 17s was demonstrated in a mouse model
of LPS-stimulated TNF-a production. This validates
the strategy of focusing on structural changes of the
P1 group on this scaffold to dramatically improve
selectivity while retaining sufficient cell activity. Com-
pound 17s is an excellent lead for the further optimi-
zation of this scaffold through variation of the P1
moiety.
Acknowledgments
We thank the Discovery Analytical Chemistry group for
spectral data and Q. Wang for PK data. We thank Drs.
John Ellingboe and Jerry Skotnicki for their support of
this work.
As expected, the piperidine sulfonamides, 17q–17u, are
also all potent inhibitors of cell-free TACE enzyme.
Methanesulfonamide 17q shows good selectivity over
MMP-2, but the benzyl and n-butyl sulfonamides, 17r
and 17t, are both minimally selective over MMP-2 and
MMP-9. However, surprisingly, isopropyl sulfonamide
17s shows greater than 100-fold selectivity over all five
MMPs screened, with greater than 1000-fold selectivity
over MMP-1, MMP-9 and MMP-14. This favorable
selectivity profile may be due to a combination of both
the steric bulk of isopropyl P1 moiety and an electronic
effect of the P1 sulfonamide functionality. Coincidental-
ly, this compound is also among the most potent of the
b-piperidine sulfone hydroxamates in human whole
blood, with an IC50 of 1.5 lM, although its activity in
Raw cells is only moderate. Among the ureas prepared,
17v–17x, the bulky diethyl urea 17x is greater than
200-fold selective over MMP-2, but only approximately
50-fold selective over MMP-13. Of the ureas, compound
17x also has the best activity in Raw cells and moderate
activity in HWB. Clearly the isopropyl sulfonamide P1
group of 17s provides the best combination of activity
against TACE, selectivity over a variety of MMPs,
and activity in human whole blood.
References and notes
1. Killar, L.; White, J.; Black, R.; Peschon, J. Ann. N.Y.
Acad. Sci. 1999, 878, 442.
2. (a) Roberts, L.; McColl, G. J. Intern. Med. J. 2004, 34,
687; (b) Hyrich, K. L.; Silman, A. J.; Watson, K. D.;
Symmons, D. P. M. Ann. Rheum. Dis. 2004, 63, 1538; (c)
Feldmann, M.; Maini, R. N. Annu. Rev. Immunol. 2001,
19, 163.
3. Feldmann, M.; Brennan, F. M.; Foxwell, B. M.; Maaini,
R. N. Curr. Dir. Autoimmun. 2001, 3, 188.
4. (a) Kobelt, G.; Lindgren, P.; Singh, A.; Klareskog, L. Ann.
Rheum. Dis. 2005, 64, 1174; (b) Baumgartner, S. W.;
Fleischmann, R. M.; Moreland, L. W.; Schiff, M. H.;
Markenson, J.; Whitmore, J. B. J. Rheumatol. 2004, 31,
1532; (c) Terslev, L.; Torp-Pedersen, S.; Qvistgaard, E.;
Kristoffersen, H.; Rogind, H.; Danneskiold-Samsoe, B.;
Bliddal, H. Ann. Rheum. Dis. 2003, 62, 178.
5. (a) Asif, M.; Siddiqui, A.; Scott, L. J. Drugs 2005, 65,
2179; (b) Familian, A.; Voskuyl, A. E.; van Mierlo, G. J.;
Heijst, H. A.; Twisk, J. W. R.; Dijkmans, B. A. C.; Hack,
C. E. Ann. Rheum. Dis. 2005, 64, 1003; (c) St Clair, E. W.;
van der Heijde, D. M. F. M.; Smolen, J. S.; Maini, R. N.;
Bathon, J. M.; Emery, P.; Keystone, E.; Shiff, M.; Kalden,
J. R.; Wang, B.; de Woody, K.; Weiss, R.; Baker, D.
Arthritis Rheum. 2004, 50, 3432.
Due to its excellent potency and selectivity, 17s was test-
ed for its ability to inhibit LPS-stimulated production of
TNF-a in a mouse after oral dosing.16 At 25 mg/kg po,
compound 17s provided greater than 72% inhibition of
TNF-a production 1 h after administration of LPS. In
a rat pharmacokinetic study, compound 17s, dosed at
5 mg/kg iv, had a short half-life (0.5 h), and moderate
6. (a) Skotnicki, J. S.; Levin, J. I. Annu. Rep. Med. Chem.
2003, 38, 153; (b) Duan, J.-W.; Lu, Z.; Wasserman, Z. R.;
Liu, R.-Q.; Covington, M. B.; Decicco, C. P. Bioorg. Med.
Chem. Lett. 2005, 15, 2970; (c) Kamei, N.; Tanaka, T.;
Kawai, K.; Miyawaki, K.; Okuyama, A.; Murakami, Y.;
Arakawa, Y.; Haino, M.; Harada, T.; Shimano, M.