Abstract: Recombinant immunotoxins are fusion proteins composed of the Fv domains of antibodies fused to bacterial or plant toxins. RFB4 (Fv)-PE38 is an immunotoxin that targets CD22 expressed on B cells and B cell malignancies. The present invention provides antibodies and antibody fragments that have improved ability to bind the CD22 antigen of B cells and B cell malignancies compared to RFB4. Immunotoxins made with the antibodies and antibody fragments of the invention have improved cytotoxicity to CD22-expressing cancer cells. Compositions that incorporate these antibodies into chimeric immunotoxin molecules that can be used in medicaments and methods for inhibiting the growth and proliferation of leukemia and lymphoma cells.

Abstract: Recombinant immunotoxins are fusion proteins composed of the Fv domains of antibodies fused to bacterial or plant toxins. RFB4 (Fv)-PE38 is an immunotoxin that targets CD22 expressed on B cells and B cell malignancies. The present invention provides antibodies and antibody fragments that have improved ability to bind the CD22 antigen of B cells and B cell malignancies compared to RFB4. Immunotoxins made with the antibodies and antibody fragments of the invention have improved cytotoxicity to CD22-expressing cancer cells. Compositions that incorporate these antibodies into chimeric immunotoxin molecules that can be used in medicaments and methods for inhibiting the growth and proliferation of leukemia and lymphoma cells.

Abstract: Recombinant immunotoxins are fusion proteins composed of the Fv domains of antibodies fused to bacterial or plant toxins. RFB4 (Fv)-PE38 is an immunotoxin that targets CD22 expressed on B cells and B cell malignancies. The present invention provides antibodies and antibody fragments that have improved ability to bind the CD22 antigen of B cells and B cell malignancies compared to RFB4. Immunotoxins made with the antibodies and antibody fragments of the invention have improved cytotoxicity to CD22-expressing cancer cells. Compositions that incorporate these antibodies into chimeric immunotoxin molecules that can be used in medicaments and methods for inhibiting the growth and proliferation of leukemia and lymphoma cells.

Abstract: The invention provides recombinant immunotoxins that have been modified from a parental immunotoxin to lower liver toxicity. The immunotoxins are created by specifically mutating charged residues in the framework regions of the heavy chain, the light chain, or both, of the antibody portion or antigen-binding fragment thereof of the parental immunotoxin to reduce the pI of the antibody or fragment. In preferred forms, the antibody portion of the parental is an anti-Tac, anti-mesothelin, or anti-LewisY antigen antibody or antigen-binding fragment, and in particularly preferred forms the antibody portion is an M16 dsFv, a St6 dsFv or a Mt9 dsFv, or a sequence that has at least 90% sequence identity to one of these molecules but retain the particular mutations that lower pI without affecting antibody activity. The invention further provides nucleic acids encoding the recombinant immunotoxins of the invention, expression cassettes comprising the nucleic acids, and host cells comprising the expression cassettes.

Abstract: Recombinant immunotoxins are fusion proteins composed of the Fv domains of antibodies fused to bacterial or plant toxins. RFB4 (Fv)-PE38 is an immunotoxin that targets CD22 expressed on B cells and B cell malignancies. The present invention provides antibodies and antibody fragments that have improved ability to bind the CD22 antigen of B cells and B cell malignancies compared to RFB4. Immunotoxins made with the antibodies and antibody fragments of the invention have improved cytotoxicity to CD22-expressing cancer cells. Compositions that incorporate these antibodies into chimeric immunotoxin molecules that can be used in medicaments and methods for inhibiting the growth and proliferation of leukemia and lymphoma cells.

Abstract: Recombinant immunotoxins are fusion proteins composed of the Fv domains of antibodies fused to bacterial or plant toxins. RFB4 (Fv)-PE38 is an immunotoxin that targets CD22 expressed on B cells and B cell malignancies. The present invention provides antibodies and antibody fragments that have improved ability to bind the CD22 antigen of B cells and B cell malignancies compared to RFB4. Immunotoxins made with the antibodies and antibody fragments of the invention have improved cytotoxicity to CD22-expressing cancer cells. Compositions that incorporate these antibodies into chimeric immunotoxin molecules that can be used in medicaments and methods for inhibiting the growth and proliferation of leukemia and lymphoma cells.

Abstract: The invention provides recombinant immunotoxins that have been modified from a parental immunotoxin to lower liver toxicity. The immunotoxins are created by specifically mutating charged residues in the framework regions of the heavy chain, the light chain, or both, of the antibody portion or antigen-binding fragment thereof of the parental immunotoxin to reduce the pI of the antibody or fragment. In preferred forms, the antibody portion of the parental is an anti-Tac, anti-mesothelin, or anti-LewisY antigen antibody or antigen-binding fragment, and in particularly preferred forms the antibody portion is an M16 dsFv, a St6 dsFv or a Mt9 dsFv, or a sequence that has at least 90% sequence identity to one of these molecules but retain the particular mutations that lower pI without affecting antibody activity. The invention further provides nucleic acids encoding the recombinant immunotoxins of the invention, expression cassettes comprising the nucleic acids, and host cells comprising the expression cassettes.

Abstract: The present invention is directed to the site-specific PEGylation of immunoconjugates. In particular, the present invention provides immunoconjugates wherein a connector molecule attaching a targeting molecule to an effector molecule is conjugated to one or more polyethylene glycol molecules. The present invention further provides methods for increasing the antitumor activity of an immunotoxin, comprising attaching in a site-specific manner one or more polyethylene glycol molecules to a linker connecting a toxic moiety to a targeting moiety of an immunotoxin.

Abstract: The present invention provides for circularly permuted ligands which possess specificity and binding affinity comparable to or greater than the specificity and binding affinity of the original (unpermuted) ligand. The invention further provides for novel chimeric molecules comprising a circularly permuted ligand joined to one or more molecules of interest.

Abstract: The present invention provides for circularly permuted ligands which possess specificity and binding affinity comparable to or greater than the specificity and binding affinity of the original (unpermuted) ligand. The invention further provides for novel fusion proteins comprising a circularly permuted ligand fused to one or more proteins of interest.