Amyloid plaque aggregation inhibitors and diagnostic imaging...

Details Amyloid plaque aggregation inhibitors and diagnostic imaging... Amyloid plaque aggregation inhibitors and diagnostic imaging...

2002-04-23

2004-02-24

Jones, Dameron L. (Department: 1616)

Drug, bio-affecting and body treating compositions

Radionuclide or intended radionuclide containing; adjuvant...

In an organic compound

Reexamination Certificate

active

06696039

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to novel bioactive compounds, methods of diagnostic imaging using radiolabeled compounds, and methods of making radiolabeled compounds.
2. Background Art
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, irreversible memory loss, disorientation, and language impairment. Postmortem examination of AD brain sections reveals abundant senile plaques (SPs) composed of amyloid-&bgr; (A&bgr;) peptides and numerous neurofibrillary tangles (NFTs) formed by filaments of highly phosphorylated tau proteins (for recent reviews and additional citations see Ginsberg, S. D., et al., “Molecular Pathology of Alzheimer's Disease and Related Disorders,” in
Cerebral Cortex. Neurodegenerative and Age
-
related Changes in Structure and Function of Cerebral Cortex
, Kluwer Academic/Plenum, New York (1999), pp. 603-654; Vogelsberg-Ragaglia, V., et al, “Cell Biology of Tau and Cytoskeletal Pathology in Alzheimer's Disease,”
Alzheimer's Disease
, Lippincot, Williams & Wilkins, Philadelphia, P.A. (1999), pp.359-372). Familial AD (FAD) is caused by multiple mutations in the A precursor protein (APP), presenilin 1 (PS1) and presenilin 2 (PS2) genes (Ginsberg, S. D., et al., “Molecular Pathology of Alzheimer's Disease and Related Disorders,” in
Cerebral Cortex: Neurodegenerative and Age
-
related Changes in Structure and Function of Cerebral Cortex
, Kluwer Academic/Plenum, New York (1999), pp. 603-654; Vogelsberg-Ragaglia, V., et al., “Cell Biology of Tau and Cytoskeletal Pathology in Alzheimer's Disease,”
Alzheimer's Disease
, Lippincot, Williams & Wilkins, Philadelphia, P.A. (1999), pp. 359-372).
While the exact mechanisms underlying AD are not fully understood, all pathogenic FAD mutations studied thus far increase production of the more amyloidogenic 42-43 amino-acid long form of the A&bgr; peptide. Thus, at least in FAD, dysregulation of A&bgr; production appears to be sufficient to induce a cascade of events leading to neurodegeneration. Indeed, the amyloid cascade hypothesis suggests that formation of extracellular fibrillar A&bgr; aggregates in the brain may be a pivotal event in AD pathogenesis (Selkoe, D. J., “Biology of B-amyloid Precursor Protein and the Mechanism of Alzheimer's Disease,”
Alzheimer's Disease
, Lippincot Williams & Wilkins, Philadelphia, P.A. (1999), pp. 293-310; Selkoe, D. J.,
J. Am. Med. Assoc.
283:1615-1617 (2000); Naslund, J., et al.,
J. Am. Med. Assoc.
283:1571-1577 (2000); Golde, T. E., et al.,
Biochimica et Biophysica Acta
1502:172-187 (2000)).
Various approaches in trying to inhibit the production and reduce the accumulation of fibrillar A&bgr; in the brain are currently being evaluated as potential therapies for AD (Skovronsky, D. M. and Lee, V. M.,
Trends Pharmacol. Sci.
21:161-163 (2000); Vassar, R., et al.,
Science
286:735-741 (1999); Wolfe, M. S., et al.,
J. Med. Chem.
41:6-9 (1998); Moore, C. L., et al.,
J. Med. Chem.
43:3434-3442 (2000); Findeis, M. A.,
Biochimica et Biophysica Acta
1502:76-84 (2000); Kuner, P., Bohrmann, et al.,
J. Biol. Chem.
275:1673-1678 (2000)). It is therefore of great interest to develop ligands that specifically bind fibrillar A&bgr; aggregates. Since extracellular SPs are accessible targets, these new ligands could be used as in vivo diagnostic tools and as probes to visualize the progressive deposition of A&bgr; in studies of AD amyloidogenesis in living patients.
To this end, several interesting approaches for developing fibrillar A&bgr; aggregate-specific ligands have been reported (Ashburn, T. T., et al.,
Chem. Biol.
3:351-358 (1996); Han, G., et al.,
J. Am. Chem. Soc.
118:4506-4507 (1996); Klunk, W. E., et al.,
Biol. Psychiatry
35:627 (1994); Klunk, W. E., et al.,
Neurobiol. Aging
16:541-548 (1995); Klunk, W. E., et al.,
Society for Neuroscience Abstract
23:1638 (1997); Mathis, C. A., et al.,
Proc. XIIth Intl. Symp. Radiopharm. Chem., Uppsala, Sweden:
94-95 (1997); Lorenzo, A. and Yankner, B. A.,
Proc. Natl. Acad. Sci. US.A.
91:12243-12247 (1994); Zhen, W., et al.,
J. Med. Chem.
42:2805-2815 (1999)). The most attractive approach is based on highly conjugated chrysamine-G (CG) and Congo red (CR), and the latter has been used for fluorescent staining of SPs and NFTs in postmortem AD brain sections (Ashburn, T. T., et al.,
Chem. Biol.
3:351-358 (1996); Klunk, W. E., et al.,
J. Histochem. Cytochem.
37:1273-1281 (1989)). The inhibition constants (K
i
) for binding to fibrillar A&bgr; aggregates of CR, CG, and 3′-bromo- and 3′-iodo derivatives of CG are 2,800, 370, 300 and 250 nM, respectively (Mathis, C. A., et al.,
Proc. XIIth Intl. Symp. Radiopharm. Chem., Uppsala, Sweden:
94-95 (1997)). These compounds have been shown to bind selectively to A&bgr; (1-40) peptide aggregates in vitro as well as to fibrillar A&bgr; deposits in AD brain sections (Mathis, C. A., et al.,
Proc. XIIth Intl. Symp. Radiopharm. Chem., Uppsala, Sweden:
94-95 (1997)).
Amyloidosis is a condition characterized by the accumulation of various insoluble, fibrillar proteins in the tissues of a patient. An amyloid deposit is formed by the aggregation of amyloid proteins, followed by the further combination of aggregates and/or amyloid proteins.
In addition to the role of amyloid deposits in Alzheimer's disease, the presence of amyloid deposits has been shown in diseases such as Mediterranean fever, Muckle-Wells syndrome, idiopathetic myeloma, amyloid polyneuropathy, amyloid cardiomyopathy, systemic senile amyloidosis, amyloid polyneuropathy, hereditary cerebral hemorrhage with amyloidosis, Down's syndrome, Scrapie, Creutzfeldt-Jacob disease, Kuru, Gerstamnn-Straussler-Scheinker syndrome, medullary carcinoma of the thyroid, Isolated atrial amyloid, &bgr;
2
-microglobulin amyloid in dialysis patients, inclusion body myositis, &bgr;
2
-amyloid deposits in muscle wasting disease, and Islets of Langerhans diabetes Type II insulinoma.
Thus, a simple, noninvasive method for detecting and quantitating amyloid deposits in a patient has been eagerly sought. Presently, detection of amyloid deposits involves histological analysis of biopsy or autopsy materials. Both methods have drawbacks. For example, an autopsy can only be used for a postmortem diagnosis.
The direct imaging of amyloid deposits in vivo is difficult, as the deposits have many of the same physical properties (e.g., density and water content) as normal tissues. Attempts to image amyloid deposits using magnetic resonance imaging (MRI) and computer-assisted tomography (CAT) have been disappointing and have detected amyloid deposits only under certain favorable conditions. In addition, efforts to label amyloid deposits with antibodies, serum amyloid P protein, or other probe molecules have provided some selectivity on the periphery of tissues, but have provided for poor imaging of tissue interiors.
Potential ligands for detecting A&bgr; aggregates in the living brain must cross the intact blood-brain barrier. Thus brain uptake can be improved by using ligands with relatively smaller molecular size (compared to Congo Red) and increased lipophilicity. Highly conjugated thioflavins (S and T) are commonly used as dyes for staining the A&bgr; aggregates in the AD brain (Elhaddaoui, A., et al.,
Biospectroscopy
1: 351-356 (1995)). These compounds are based on benzothiazole, which is relatively small in molecular size. However, thioflavins contain an ionic quarternary amine, which is permanently charged and unfavorable for brain uptake.
Thus, it would be useful to have a noninvasive technique for imaging and quantitating amyloid deposits in a patient. In addition, it would be useful to have compounds that inhibit the aggregation of amyloid proteins to form amyloid deposits and a method for determining a compound's ability to inhibit amyloid protein aggregation.
BRIEF SUMMARY OF THE INVENTION
The present invention provides novel compounds of Formula I, II, III or III′ that bin

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