Mutant diphtheria toxin conjugates
First Claim
1. A toxin conjugate comprising (i) a mutant diphtheria toxin, wherein said mutant diphtheria toxin has a cell surface receptor binding site that binds to said cell surface receptor with an affinity lower than that of wild-type diphtheria toxin and a translocation function, and has an amino acid point mutation of serine residue 508 or of serine residue 525, covalently attached to (ii) a binding moiety which binds to a specific receptor;
- wherein said translocation function is measured by a cytotoxicity assay using said conjugate and a cell expressing said specific receptor.
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Accused Products
Abstract
A potent and specific immunotoxin is prepared by coupling an inactivated diphtheria toxin to a binding moiety such as a monoclonal antibody or transferrin. The immunotoxins are specific for human tumors and leukemias and are indistinguishable in cell toxicity from that of the native toxin linked to the binding domain without the toxicity to other cells. The immunotoxin is useful in treating graft versus host disease as well as selectively killing tumor cells, such as medulloblastoma and glioblastoma cells.
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Citations
39 Claims
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1. A toxin conjugate comprising (i) a mutant diphtheria toxin, wherein said mutant diphtheria toxin has a cell surface receptor binding site that binds to said cell surface receptor with an affinity lower than that of wild-type diphtheria toxin and a translocation function, and has an amino acid point mutation of serine residue 508 or of serine residue 525, covalently attached to (ii) a binding moiety which binds to a specific receptor;
wherein said translocation function is measured by a cytotoxicity assay using said conjugate and a cell expressing said specific receptor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for enhancing the selectivity of a mutant diphtheria toxin which comprises covalently attaching (i) a mutant diphtheria toxin, wherein said mutant diphtheria toxin has a cell surface receptor binding site that binds to said cell surface receptor with an affinity lower than that of wild-type diphtheria toxin and a translocation function, and having an amino acid point mutation of serine residue 508, or an amino acid point mutation of serine residue 525, to (ii) a binding moiety which binds to a specific receptor;
wherein said translocation function is measured by a cytotoxicity assay using said conjugate and a cell expressing said specific receptor. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A toxin conjugate comprising (i) a binding moiety which specifically binds to a receptor of a cell of a neural cell tumor, a glial cell tumor, a metastatic small cell lung carcinoma or metastatic breast carcinoma tumor and (ii) a mutant diphtheria toxin, wherein said mutant diphtheria toxin consists of an A chain polypeptide and a B chain polypeptide, wherein said B chain polypeptide has a cell surface receptor binding site that binds to said cell surface receptor with a binding affinity lower than that of wild-type diphtheria toxin and an A chain translocating activity, and wherein said B chain has an amino acid point mutation of serine residue 508 or of serine residue 525, wherein said binding moiety is covalently linked to said mutant diphtheria toxin;
wherein said A chain translocating activity is measured by a cytotoxicity assay using said conjugate and a cell expressing said specific receptor. - View Dependent Claims (26, 27, 28, 29, 30)
- 31. A toxin conjugate comprising (i) a mutant diphtheria toxin, wherein said mutant diphtheria toxin has a cell surface receptor binding site that binds to said cell surface receptor with an affinity lower than that of wild-type diphtheria toxin and has a point mutation of serine residue 508 and a point mutation of proline residue 308, covalently attached to (ii) a binding moiety which binds to a specific receptor.
- 38. A toxin conjugate comprising (i) a mutant diphtheria toxin, wherein said mutant diphtheria toxin consists of an A chain polypeptide and a B chain polypeptide, wherein said B chain polypeptide has a cell surface receptor binding site that binds to said cell surface receptor with a binding affinity lower than that of wild-type diphtheria toxin and has a point mutation of serine residue 508 and a point mutation of proline residue 308, covalently attached to (ii) a binding moiety which specifically binds to a receptor of a cell of a neural cell tumor, a glial cell tumor, a metastatic small cell lung carcinoma or a metastatic breast carcinoma tumor.
Specification