Protease inhibitors

Details Protease inhibitors Protease inhibitors

2001-07-30

2003-05-20

Shah, Mukund J. (Department: 1624)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Having -c-, wherein x is chalcogen, bonded directly to...

C549S465000, C549S055000, C549S321000, C549S293000, C549S468000, C546S172000, C546S169000, C546S284700, C546S214000, C548S465000, C514S464000, C514S443000, C514S472000, C514S459000, C514S414000, C514S336000, C514S326000, C514S469000

Reexamination Certificate

active

06566373

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to novel protease inhibitors, particularly inhibitors of cysteine and serine proteases, more particularly compounds which inhibit cysteine proteases. The compounds of this invention even more particularly relate to those compounds which inhibit cysteine proteases of the papain superfamily, and particularly cysteine proteases of the cathepsin family. In the most preferred embodiment, this invention relates to compounds which inhibit cathepsin K. Such compounds are particularly useful for treating diseases in which cysteine proteases are implicated, especially diseases of excessive bone or cartilage loss, e.g., osteoporosis, periodontitis, and arthritis.
BACKGROUND OF THE INVENTION
Cathepsin K is a member of the family of enzymes which are part of the papain superfamily of cysteine proteases. Cathepsins B, H, L, N and S have been described in the literature. Recently, cathepsin K polypeptide and the cDNA encoding such polypeptide were disclosed in U.S. Pat. No. 5,501,969 (called cathepsin O therein). Cathepsin K has been recently expressed, purified, and characterized. Bossard, M. J., et al., (1996)
J. Biol. Chem.
271, 12517-12524; Drake, F. H., et al., (1996)
J. Biol. Chem.
271, 12511-12516; Bromme, D., et al., (1996)
J. Biol. Chem.
271, 2126-2132.
Cathepsin K has been variously denoted as cathepsin O, cathepsin X or cathepsin O2 in the literature. The designation cathepsin K is considered to be the more appropriate one (name assigned by Nomenclature Committee of the International Union of Biochemistry and Molecular Biology).
Cathepsins of the papain superfamily of cysteine proteases function in the normal physiological process of protein degradation in animals, including humans, e.g., in the degradation of connective tissue. However, elevated levels of these enzymes in the body can result in pathological conditions leading to disease. Thus, cathepsins have been implicated in various disease states, including but not limited to, infections by pneumocystis carinii, trypsanoma cruzi, trypsanoma brucei brucei, and Crithidia fusiculata; as well as in schistosomiasis malaria, tumor metastasis, metachromatic leukodystrophy, muscular dystrophy, amytrophy, and the like. See International Publication Number WO 94/04172, published on Mar. 3, 1994, and references cited therein. See also European Patent Application EP 0 603 873 A1, and references cited therein. Two bacterial cysteine proteases from
P. gingivallis
, called gingipains, have been implicated in the pathogenesis of gingivitis. Potempa, J., et al. (1994)
Perspectives in Drug Discovery and Design,
2, 445-458.
Cathepsin K is believed to play a causative role in diseases of excessive bone or cartilage loss. Bone is composed of a protein matrix in which spindle- or plate-shaped crystals of hydroxyapatite are incorporated. Type I Collagen represents the major structural protein of bone comprising approximately 90% of the structural protein. The remaining 10% of matrix is composed of a number of non-collagenous proteins, including osteocalcin, proteoglycans, osteopontin, osteonectin, thrombospondin, fibronectin, and bone sialoprotein. Skeletal bone undergoes remodeling at discrete foci throughout life. These foci, or remodeling units, undergo a cycle consisting of a bone resorption phase followed by a phase of bone replacement.
Bone resorption is carried out by osteoclasts, which are multinuclear cells of hematopoietic lineage. The osteoclasts adhere to the bone surface and form a tight sealing zone, followed by extensive membrane ruffling on their apical (i.e., resorbing) surface. This creates an enclosed extracellular compartment on the bone surface that is acidified by proton pumps in the ruffled membrane, and into which the osteoclast secretes proteolytic enzymes. The low pH of the compartment dissolves hydroxyapatite crystals at the bone surface, while the proteolytic enzymes digest the protein matrix. In this way, a resorption lacuna, or pit, is formed. At the end of this phase of the cycle, osteoblasts lay down a new protein matrix that is subsequently mineralized. In several disease states, such as osteoporosis and Paget's disease, the normal balance between bone resorption and formation is disrupted, and there is a net loss of bone at each cycle. Ultimately, this leads to weakening of the bone and may result in increased fracture risk with minimal trauma.
The abundant selective expression of cathepsin K in osteoclasts strongly suggests that this enzyme is essential for bone resorption. Thus, selective inhibition of cathepsin K may provide an effective treatment for diseases of excessive bone loss, including, but not limited to, osteoporosis, gingival diseases such as gingivitis and periodontitis, Paget's disease, hypercalcemia of malignancy, and metabolic bone disease. Cathepsin K levels have also been demonstrated to be elevated in chondroclasts of osteoarthritic synovium. Thus, selective inhibition of cathepsin K may also be useful for treating diseases of excessive cartilage or matrix degradation, including, but not limited to, osteoarthritis and rheumatoid arthritis. Metastatic neoplastic cells also typically express high levels of proteolytic enzymes that degrade the surrounding matrix. Thus, selective inhibition of cathepsin K may also be useful for treating certain neoplastic diseases.
It now has been discovered that a novel class of compounds are protease inhibitors, most particularly inhibitors of cathepsin K, and these compounds are useful for treating diseases in which inhibition of bone resorption is indicated, such as osteoporosis and periodontal disease.
SUMMARY OF THE INVENTION
An object of the present invention is to provide protease inhibitors, such as inhibitors of cysteine and serine proteases. In particular, the present invention relates to compounds which inhibit cysteine proteases, and particularly cysteine proteases of the papain superfamily. Preferably, this invention relates to compounds which inhibit cysteine proteases of the cathepsin family and particularly, compounds which inhibit cathepsin K. The compounds of the present invention are useful for treating diseases, which may be therapeutically modified by altering the activity of such proteases.
Accordingly, in the first aspect, this invention provides a compound according to formula (I):
In another aspect, this invention provides a pharmaceutical composition comprising a compound according to formula (I) and a pharmaceutically acceptable carrier.
In yet another aspect, this invention provides a method of treating diseases in which the disease pathology may be therapeutically modified by inhibiting proteases, such as cysteine and serine proteases. In particular, the method includes treating diseases by inhibiting cysteine proteases, and particularly cysteine proteases of the papain superfamily. More particularly, the inhibition of cysteine proteases of the cathepsin family, such as cathepsin K is described.
In another aspect, the compounds of this invention are especially useful for treating diseases characterized by bone loss, such as osteoporosis and gingival diseases, such as gingivitis and periodontitis, or by excessive cartilage or matrix degradation, such as osteoarthritis and rheumatoid arthritis.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides compounds of formula (I):
wherein:
R
1
is R″, R″C(O), R″C(S), R″SO
2
, R″OC(O), R″R′NC(O), or R″OC(O)NR′CH(R
6
)C(O);
R
2
is H, C
1-6
alkyl, C
2-6
alkenyl, Ar-C
0-6
alkyl, or Het-C
0-6
alkyl;
R
3
is H, C
1-6
alkyl, C
2-6
alkenyl, C
2-6
alkynyl, C
3-6
cycloalkyl-C
0-6
alkyl, Ar-C
0-6
alkyl, or Het-C
0-6
alkyl;
R
4
is H, C
1-6
alkyl, C
2-6
alkenyl, Ar-C
0-6
alkyl, or Het-C
0-6
alkyl;
each R
5
independently is H, C
1-6
alkyl, C
2-6
alkenyl, Ar-C
0-6
alkyl, or Het-C
0-6
alkyl;
R
6
is H, C
1-6
alkyl, C
2-6
alkenyl, C
3-6
cycloalkyl-C
0-6
-alkyl, Ar-C
0-6
alkyl, Het-C
0-6
alkyl;
R′ is H, C
1-6
alkyl, C
2-6
alkenyl, Ar-C
0-6
alkyl, or Het-C
0-6
alkyl;
R&P

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