Enzyme-cleavable prodrug compounds

1. A compound comprising:

(1) a therapeutic agent capable of entering a target cell, wherein said therapeutic agent is an alkylating agent, antiproliferative agent, tubulin binding agent, vinca alkaloid, enediyne, podophyllotoxin, podophyllotoxin derivative, a member of the pteridine family of drugs, taxane, a dolastatin, topoiosomerase inhibitor, or a platinum complex chemotherapeutic agent,

(2) an oligopeptide of the formula (AA) n -AA 4 -AA 3 -AA 2 -AA 1 , wherein:

each AA independently represents an amino acid,

n is an integer from 0 to 16,

AA 4 represents β-alanine, thiazolidine-4-carboxylic acid, 2-thienylalanine, 2-naphthylalanine, D-alanine, D-leucine, D-methionine, D-phenylalanine, 3-amino-3-phenylpropionic acid, γ-aminobutyric acid, 3-amino-4,4-diphenylbutyric acid, tetrahydroisoquinoline-3-carboxylic acid, 4-aminomethylbenzoic acid, and aminoisobutyric acid,

AA 3 represents any amino acid,

AA 2 represents any amino acid, and

AA 1 represents any amino acid,

(3) a negatively charged stabilizing group, and

(4) optionally, a linker group not cleavable by TOP,

wherein the oligopeptide is directly linked to the stabilizing group at the amino terminus of the oligopeptide and the oligopeptide is directly linked to the therapeutic agent or indirectly linked through the linker group to the therapeutic agent at a second attachment site of the oligopeptide,

wherein the stabilizing group reduces acute toxicity of the compound when administered in vivo, and

wherein the compound is cleavable by TOP.

2. The compound of claim 1 wherein the oligopeptide is selected from the group consisting of: D-AlaThiβAlaβAlaLeuAlaLeu (SEQ ID NO: 1), ThiβAlaβAlaLeuAlaLeu (SEQ ID NO: 2), βAlaβAlaLeuAlaLeu (SEQ ID NO: 3), βAlaLeuTyrLeu (SEQ ID NO: 17),βAlaLeuThiLeu (SEQ ID NO: 18), βAlaLeuThrLeu (SEQ ID NO: 21), βAlaLeuSerLeu (SEQ ID NO: 22), βAlaLeuPyrLeu (SEQ ID NO: 23), βAlaLeuLeuLeu (SEQ ID NO: 24), βAlaLeuGlyLeu (SEQ ID NO: 28), βAlaLeuPheLeu (SEQ ID NO: 31), βAlaLeuAibLeu (SEQ ID NO: 32), and βAlaLeuAlaLeu (SEQ ID NO: 38).

3. The compound of claim 1 wherein AA 1 of the oligopeptide is selected from the group consisting of Leucine, Phenylalanine, Isoleucine, Alanine, Glycine, Tyrosine, 2-Naphthylalanine, Serine, p-Cl-phenylalanine, p-Nitrophenylalanine, 1-Naphthylalanine, Threonine, Homoserine, Cyclohexylalanine, Thienylalanine, Homophenylalanine, Norleucine, and β-Alanine.

4. The compound of claim 1 wherein AA 2 of the oligopeptide is selected from the group consisting of Alanine, Leucine, Tyrosine, Glycine, Serine, 3-Pyridylalanine, 2-Thienylalanine, Norleucine, Homoserine, Homophenylalanine, p-Cl-phenylalanine, p-Nitrophenylalanine, Aminoisobutyric Acid, Threonine, and Phenylalanine.

5. The compound of claim 1 wherein AA 3 of the oligopeptide is selected from the group consisting of Leucine, Tyrosine, Phenylalanine, p-Cl-Phenylalanine, p-Nitrophenylalanine, Valine, Norleucine, Norvaline, Phenylglycine, Tryptophan, Tetrahydroisoquinoline-3-carboxylic acid, 3-Pyridylalanine, Alanine, Glycine, Thienylalanine, Methionine, Valine, and Proline.

6. The compound of claim 1 wherein the stabilizing group is a dicarboxylic or higher order carboxylic acid.

7. The compound of claim 1 wherein the stabilizing group is selected from the group consisting of: succinic acid, adipic acid, glutaric acid, phthalic acid, diglycolic acid, fumaric acid, naphthalene dicarboxylic acid, 1,8-naphthyl dicarboxylic acid, aconitic acid, carboxycinnamic acid, triazole dicarboxylic acid, butane disulfonic acid, and maleic acid.

8. The compound of claim 1 wherein the stabilizing group is a non-genetically encoded amino acid having four or more carbons.

9. The compound of claim 1 wherein the stabilizing group is one of aspartic acid linked to the oligopeptide at the β-carboxy group of the aspartic acid or glutamic acid linked to the oligopeptide at the γ-carboxy group of the glutamic acid.

10. The compound of claim 1 wherein the therapeutic agent is selected from the group consisting of Doxorubicin, Daunorubicin, Vinblastine, Vincristine, Calicheamicin, Etoposide, Etoposide phosphate, CC-1065, Duocarmycin, KW-2189, Methotrexate, Methopterin, Aminopterin, Dichloromethotrexate, Docetaxel, Paclitaxel, Epithiolone, Combretastatin, Combretastatin A4 Phosphate, Dolastatin 10, Dolastatin 11, Dolostatin 15, Topotecan, Camptothecin, Mitomycin C, Porfiromycin, 5-Fluorouracil, 6-Mercaptopurine, Fludarabine, Tamoxifen, Cytosine arabinoside, Adenosine arabinoside, Colchicine, Cisplatin, Carboplatin, Mitomycin C, Bleomycin, Melphalan, Chloroquine, Cyclosporin A, and a derivative of any of the foregoing.

11. The compound of claim 1 wherein the oligopeptide is directly linked to the therapeutic agent.

12. The compound of claim 1 wherein the oligopeptide sequence is indirectly linked to the therapeutic agent at the second attachment site of the oligopeptide via a linker group, the linker group selected from the group consisting of amino caproic acid, a hydrazide group, an ester group, an ether group, and a sulphydryl group.

13. A compound selected from the group consisting of Suc-βAla-Leu-Ala-Leu-Dox, (Suc-(SEQ ID NO:38), Suc-βAla-Leu-Ala-Leu-Dnr (Suc-(SEQ ID NO:38)-Dnr) and Glutaryl-βAla-Leu-Ala-Leu-Dox (Glutaryl-(SEQ ID NO:38)-Dox).

14. The compound of claim 1 wherein n is an integer from 0 to 8.

15. The compound of claim 14 wherein n is 0.

16. The compound of claim 1 wherein the oligopeptide is βAla-Leu-Ala-Leu (SEQ ID NO: 38).

17. The compound of claim 13 wherein the compound is Suc-βAla-Leu-Ala-Leu-Dox (Suc-(SEQ ID NO:38)-Dox).

18. A pharmaceutical composition comprising

(1) a compound comprising:

(a) a therapeutic agent capable of entering a target cell, wherein said therapeutic agent is an alkylating agent, antiproliferative agent, tubulin binding agent, vinca alkaloid, enedivne, podophyllotoxin, podophyllotoxin derivative, a member of the pteridine family of drugs, taxane, a dolastatin, topoiosomerase inhibitor, or a platinum complex chemotherapeutic agent,

(b) an oligopeptide of the formula (AA) n -AA 4 -AA 3 -AA 2 -AA 1 , wherein:

each AA independently represents an amino acid,

n is an integer from 0 to 16,

AA 4 represents β-alanine, thiazolidine-4-carboxylic acid, 2-thienylalanine, 2-naphthylalanine, D-alanine, D-leucine, D-methionine, D-phenylalanine, 3-amino-3-phenylpropionic acid, γ-aminobutyric acid, 3-amino-4,4-diphenylbutyric acid, tetrahydroisoquinoline-3-carboxylic acid, 4-aminomethylbenzoic acid, and aminoisobutyric acid,

AA 3 represents any amino acid,

AA 2 represents any amino acid, and

AA 1 represents any amino acid,

(c) a negatively charged stabilizing group, and

(d) optionally, a linker group not cleavable by TOP,

wherein the oligopeptide is directly linked to the stabilizing group at the amino terminus of the oligopeptide and the oligopeptide is directly linked to the therapeutic agent or indirectly linked through the linker group to the therapeutic agent at a second attachment site of the oligopeptide,

wherein the stabilizing group reduces acute toxicity of the compound when administered in vivo, and

wherein the compound is cleavable by TOP,

and (2) a pharmaceutically acceptable carrier.

19. The pharmaceutical composition of claim 18 wherein n is 0.

20. The pharmaceutical composition of claim 18 wherein the stabilizing group is selected from the group consisting of: succinic acid, adipic acid, and glutaric acid.

21. The pharmaceutical composition of claim 18 wherein the therapeutic agent is selected from the group consisting of Doxorubicin, Daunorubicin, Vinblastine, Vincristine, Calicheamicin, Etoposide, Etoposide phosphate, CC-1065, Duocarmycin, KW-2189, Methotrexate, Methopterin, Aminopterin, Dichloromethotrexate, Docetaxel, Paclitaxel, Epithiolone, Combretastatin, Combretastatin A4 Phosphate, Dolastatin 10, Dolastatin 11, Dolastatin 15, Topotecan, Camptothecin, Mitomycin C, Porfiromycin, 5-Fluorouracil, 6-Mercaptopurine, Fludarabine, Tamoxifen, Cytosine arabinoside, Adenosine arabinoside, Colchicine, Cisplatin, Carboplatin, Mitomycin C, Bleomycin, Mephalan, Chloroquine, Cyclosporin A, and a derivative of any of the foregoing.

22. The pharmaceutical composition of claim 18 wherein the oligopeptide is selected from the group consisting of: D-AlaThiβAlaβAlaLeuAlaLeu (SEQ ID NO: 1), ThiβAlaβAlaLeuAlaLeu (SEQ ID NO: 2), βAlaβAlaLeuAlaLeu (SEQ ID NO: 3), βAlaLeuTyrLeu (SEQ ID NO: 17), βAlaLeuThiLeu (SEQ ID NO: 18), βAlaLeuThrLeu (SEQ ID NO: 21), βAlaLeuSerLeu (SEQ ID NO: 22), βAlaLeuPyrLeu (SEQ ID NO: 23), βAlaLeuLeuLeu (SEQ ID NO: 24), βAlaLeuGlyLeu (SEQ ID NO: 28), βAlaLeuPheLeu (SEQ ID NO: 31), βAlaLeuAibLeu (SEQ ID NO: 32), and βAlaLeuAlaLeu (SEQ ID NO: 38).

23. A pharmaceutical composition comprising the compound of claim 17 and a pharmaceutically acceptable carrier.