# US 6,420,126 B1 · Tumor specific internalizing antigens and methods for targeting therapeutic agents

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- Number: US 6,420,126 B1
- Document ID: US6420126B1
- Status: Granted
- Kind: B1
- Application number: 09/328,128
- Filed: 1999-06-08
- Granted: 2002-07-16
- Earliest claimed: 1995-11-13
- Assignees: Ixsys, Inc.
- Inventors: William D. Huse; Jeffry D. Watkins
- Web page: https://patentgrep.com/patent/US6420126B1

## CPC

- C07K 16/30: from tumour cells
- A61P 35/00: Antineoplastic agents
- C07K 16/28: against receptors, cell surface antigens or cell surface determinants
- C07K 16/40: against enzymes
- C07K 2317/77: Internalization into the cell
- C07K: PEPTIDES (peptides in foodstuffs A23; obtaining protein compositions for foodstuffs, working-up proteins for foodstuffs A23J; preparations for medicinal purposes A61K; peptides containing beta-lactam rings C07D; cyclic dipeptides not having in their molecule any other peptide link than those which form their ring, e.g. piperazine-2,5-diones, C07D; ergot alkaloids of the cyclic peptide type C07D519/02; macromolecular compounds having statistically distributed amino acid units in their molecules, i.e. when the preparation does not provide for a specific; but for a random sequence of the amino acid units, homopolyamides and block copolyamides derived from amino acids C08G69/00; macromolecular products derived from proteins C08H1/00; preparation of glue or gelatine C09H; single cell proteins, enzymes C12N; genetic engineering processes for obtaining peptides C12N15/00; compositions for measuring or testing processes involving enzymes C12Q; investigation or analysis of biological material G01N33/00)
- A61P: SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS

## Abstract

The invention provides a method of reducing the proliferation of a neoplastic cell. The method consists of contacting the neoplastic cell with a cytotoxic or cytostatic binding agent specifically reactive with an aberrantly expressed vesicular membrane associated neoplastic cell specific internalizing antigen. The neoplastic cell specific internalizing anitgen can be selected from the group consisting of lamp-2 and limp II families of lysosomal integral membrane proteins. Also provided is a method of intracellular targeting of a cytotoxic or cytostatic agent to a neoplastic cell population. The method consists of administering to an individual containing a neoplastic cell population a cytotoxic or cytostatic binding agent specifically reactive with an aberrantly expressed vesicular membrane associated neoplastic cell specific internalizing antigen that is expressed by the neoplastic cell population, wherein the cytotoxic or cytostatic binding agent is bound by the neoplastic cell specific internalizing antigen and is internalized into the intracellular compartment. A method of reducing tumor growth through the intracellular targeting of a cytotoxic agent is also provided.

## Claims

### Claim 1

A method of diagnosing a neoplastic cell comprising contacting a cell with a binding agent specifically reactive with a vesicular antigen and measuring the amount of binding of said binding agent on the plasma membrane, increased levels of said vesicular antigen on said plasma membrane compared to a non-neoplastic cell indicating a neoplastic phenotype of said cell.

### Claim 2

The method of 1, wherein said cell is obtained from a tissue selected from breast, colon, kidney, lung, ovary, pancreas, thyroid and blood.

### Claim 3 (depends on 1)

The method of claim 1, wherein said binding agent is specifically reactive with a vesicular antigen selected from the group consisting of lamp-2 and limp II families of lysosomal integral membrane proteins and excluding lamp-1 tumor associated antigens.

### Claim 4 (depends on 1)

The method of claim 1, wherein said binding agent is specifically reactive with a vesicular antigen selected from the group consisting of p110, vacuolar-H+-ATPase, acetyl CoA:α-glucosaminide N-acetyltransferase, prosaposin, procathepsin L receptor and lysosomal acid phosphatase.

### Claim 5 (depends on 1)

The method of claim 1, wherein said binding agent is specifically reactive with the lumenal domain of the vesicular antigen.