Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or...
Reexamination Certificate
1996-12-19
2001-08-14
Huff, Sheela (Department: 1642)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
C435S388000, C435S405000, C435S406000, C435S407000
Reexamination Certificate
active
06274305
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to the inhibition of cancer cell proliferation, and, more specifically, to the testing of cancer cells for their ability to be inhibited, and to the identification and use of drugs to inhibit cancer cell proliferation.
BACKGROUND
The term “chemotherapy” simply means the treatment of disease with chemical substances. The father of chemotherapy, Paul Ehrlich, imagined the perfect chemotherapeutic as a “magic bullet;” such a compound would kill invading organisms without harming the host. This target specificity is sought in all types of chemotherapeutics, including anticancer agents.
However, specificity has been the major problem with anticancer agents. In the case of anticancer agents, the drug needs to distinguish between host cells that are cancerous and host cells that are not cancerous. The vast bulk of anticancer drugs are indiscriminate at this level. Typically anticancer agents have negative hematological effects (e.g., cessation of mitosis and disintegration of formed elements in marrow and lymphoid tissues), and immunosuppressive action (e.g., depressed cell counts), as well as a severe impact on epithelial tissues (e.g., intestinal mucosa), reproductive tissues (e.g., impairment of spermatogenesis), and the nervous system. P. Calabresi and B. A. Chabner, In: Goodman and Gilman
The Pharmacological Basis of Therapeutics
(Pergamon Press, 8th Edition) (pp. 1209-1216).
What is needed is a specific anticancer approach that is particularly suitable for specific cancer cells. Importantly, the treatment must be effective with minimal host toxicity.
SUMMARY OF THE INVENTION
The invention generally relates to the inhibition of cancer cell proliferation, and, more specifically, to the testing of cancer cells for their ability to be inhibited, and to the identification and use of drugs to inhibit cancer cell proliferation. The present invention provides A) an in vitro model for testing cancer cells and evaluating their potential for being inhibited, B) a screening assay for identifying drugs that inhibit cancer cell proliferation, and C) chemotherapeutics for inhibiting cancer cell proliferation in vivo.
A variety of assay formats are contemplated for testing the potential for inhibiting cancer cells. In one embodiment, a portion of a patient's tumor is obtained (e.g., by biopsy) and placed in tissue culture. Thereafter, the response of the cancer cells to a albumin-derived peptide is assessed. Where the albumin-derived peptide inhibits proliferation, the tumor can be considered to be expressing the corresponding plasma membrane receptor and such a tumor may be suitable for chemotherapeutics that target this receptor. The potential for reversing or overcoming this inhibition with hormone (e.g. estradiol) can also be assessed by adding the hormone to the culture. Where the inhibition with the albumin-derived peptide is cancelled by the presence of the hormone, the tumor can be considered to be expressing the corresponding plasma membrane hormone-binding receptor and such a tumor may be suitable for chemotherapeutics that target this particular receptor. Moreover, other therapies may be adopted that those skilled in the art recognize to be appropriate for “hormone sensitive” tumors.
In one embodiment, the present invention contemplates a method of evaluating human cancer comprising: a) providing i) a human cancer patient, and ii) an albumin-derived peptide; b) obtaining cancer cells from said patient; c) contacting said cells ex vivo with said albumin-derived peptide; and d) measuring cancer cell proliferation. Preferably the cancer cells are cultured in serum-free culture media so as to essentially avoid introducing complicating factors. In another embodiment, the present invention provides a method of testing human cancer cells comprising: a) providing i) a human cancer patient, ii) an albumin-derived peptide, and iii) one or more hormones or hormone analogues; b) obtaining cancer cells from said patient; c) culturing said cells in serum-free culture media in the presence of said albumin-derived peptide and said one or more hormones or hormone analogues; and d) measuring cancer cell proliferation.
As noted above, the present invention also contemplates a screening assay for identifying drugs that inhibit tumor invasion. The present invention contemplates a screening assay utilizing the binding activity of albumin-derived peptides. In one embodiment, cancer cells (whether obtained from a primary tumor or grown as an established cell line) are placed in tissue culture in the presence of an albumin-derived peptide. It is contemplated that an inhibitable tumor cells cultured in the presence of the albumin-derived peptide will not proliferate. In the drug screening assay, candidate drug inhibitors are added to a second tissue culture containing the inhibitable tumor cells (this can be done individually or in mixtures). Where the inhibitable cells are found to be similarly inhibited by the candidate drug, a drug inhibitor is indicated (hereinafter a “type 1 drug inhibitor”). It is also contemplated that the drug screening be done in the presence of a blocking hormone, i.e. a hormone that overcomes or cancels the inhibition caused by the albumin-derived peptide. For example, where the inhibition by the albumin-derived peptide is cancelled by the addition of estradiol, a candidate drug can be added in an attempt to interfere with the action of the hormone. Where the presence of estradiol does not result in proliferation, a second type of drug inhibitor is indicated (hereinafter a “type 2 drug inhibitor”). It is not intended that the present invention be limited by the nature of the drugs screened in the screening assay of the present invention. A variety of drugs, including peptides, are contemplated. Antibodies to albumin, the hormone or the corresponding receptors are contemplated as convenient positive controls.
In one embodiment, the present invention contemplates a method of screening drugs comprising: a) providing: i) albumin-inhibitable tumor cells, ii) an inhibitor selected from the group consisting of albumin, an albumin-derived peptide, and an albumin-derived peptide analogue, iii) one or more steroid hormones, and iv) a candidate drug; b) contacting said cells in vitro with said inhibitor, said one or more steroid hormones and said candidate drug; and c) measuring the extent of tumor cell proliferation.
It is not intended that the present invention be limited by the means by which the extent of proliferation is measured. A variety of quantitative and qualitative means is known in the art, including (but not limited to): 1) the uptake of radiolabelled nucleic acid precursors (e.g. tritiated thymidine), 2) microscopic examination, and 3) automated cell counting (including lysing cells and counting nuclei).
It is not intended that the present invention be limited by the nature of the cancer cells used for drug screening. Both i) cancer cells from established cancer cell lines and ii) cancer cells obtained from patients (e.g. from a biopsy) are contemplated. A variety of tumor types are contemplated as well, including, but not limited to, breast cancer cells and prostate cancer cells.
Finally, the present invention contemplates chemotherapeutics for treating cancer in vivo. In one embodiment, the present invention contemplates chemotherapeutics to inhibit cancer cell proliferation. Both type 1 and type 2 drug inhibitors identified through the above-described screening assay are contemplated. Moreover, albumin-derived peptides and peptide analogues are specifically contemplated for in vivo use. In one embodiment, the method comprises administering an albumin-derived peptide or peptide analogue as adjunct therapy with additional chemotherapeutics.
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patent: 4859585 (1989-08-01), Sonnenschein et al.
patent: 5051448 (1991-09-01), Shashoua
patent: 5135849 (1992-08-01), Soto et al.
patent: 5169862 (1992-12-01), Burke, Jr. et al.
patent: 5192746 (1993-03-01), Lobl et al.
patent: 5380712 (1995-01-01), Ballance et a
Sonnenschein Carlos
Soto Ana M.
Helms Larry R.
Huff Sheela
Medlen & Carroll LLP
Tufts University
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