Immunotoxins directed against malignant cells

Abstract

The present invention relates to immunotoxins, that effectively kill malignant cells having a given surface marker and nucleic acid constructs encoding them. These reagents comprise a toxic moiety that is derived from a Rana pipiens protein having ribonucleolytic activity linked to an antibody capable of specific binding with a chosen tumor cell.

What is claimed is:  
     
         1 . A selective cytotoxic reagent comprising an one protein having measurable ribonucleolytic activity joined to an antibody directed against a surface marker expressed by a B cell.  
     
     
         2 . The reagent of  claim 1 , wherein the one protein has the amino acid sequence of SEQ ID NO:1.  
     
     
         3 . The reagent of  claim 1 ,wherein the one protein is produced by recominant means.  
     
     
         4 . The reagent of  claim 3 , wherein the one protein has the amino acid sequence of SEQ ID NO:3.  
     
     
         5 . The reagent of  claim 3 , wherein the one protein is encoded by the nucleic acid molecule identified as SEQ ID NO:2.  
     
     
         6 . The reagent of  claim 1 , wherein the anibody is a monoclonal antibody.  
     
     
         7 . The reagent of  claim 6 , wherein the monoclonal antibody is humanized.  
     
     
         8 . the reagent of  claim 7 , wherein the monoclonal antibody is a single chain antibody.  
     
     
         9 . The reagent of  claim 1 , wherein the antibody is specific for B cell lymphomas.  
     
     
         10 . The reagent of  claim 9 , wherein the antibody is selected from the group consisting of RFB4 and LL2.  
     
     
         11 . The reagent of  claim 1 , wherein the surface marker is CD22.  
     
     
         12 . The reagent of  claim 1 , wherein the surface marker is CD74.  
     
     
         13 . The reagent of  claim 12 , wherein the antibody is LL1.  
     
     
         14 . The reagent of  claim 1 , wherein the onc protein is conjugated to the antibody through recombinant fusion.  
     
     
         15 . A nucleic acid sequence encoding the reagent of  claim 1 .  
     
     
         16 . A pharmaceutical composition comprising a selective cytotoxic reagent comprising an onc protein having measurable ribonucleolytic activity joined to an antibody directed against a cell surface marker expressed by a B cell together with a pharmaceutically acceptable carrier.  
     
     
         17 . The pharmaceutical composition of  claim 16 , wherein the onc protein has the amino acid sequence of SEQ ID NO:1.  
     
     
         18 . The pharmaceutical composition of  claim 16 , wherein the onc protein is produced by recombinant means.  
     
     
         19 . The pharmaceutical composition of  claim 18 , wherein the onc protein has the amino acid sequence of SEQ ID NO:3.  
     
     
         20 . The pharmaceutical composition of  claim 18 , wherein the onc protein is encoded by the nucleic acid molecule identified as SEQ ID NO:2.  
     
     
         21 . The pharmaceutical composition of  claim 16 , wherein the onc protein is conjugated to the antibody through recombinant means.  
     
     
         22 . The pharmaceutical composition of  claim 16 , wherein the antibody is a monoclonal antibody.  
     
     
         23 . The pharmaceutical composition of  claim 22 , wherein the monoclonal antibody is humanized.  
     
     
         24 . The pharmaceutical composition of  claim 23 , wherein the monoclonal antibody is a single chain antibody.  
     
     
         25 . The pharmaceutical composition of  claim 16 , wherein the antibody is directed against a surface marker present on B cell lymphomas.  
     
     
         26 . The pharmaceutical composition of  claim 25 , wherein the antibody is selected from the group consisting of RFB4, LL1 and LL2.  
     
     
         27 . A method of killing malignant B cells comprising contacting cells to be killed with a selective cytotoxic reagent comprising an onc protein having measurable ribonucleolytic activity joined to an antibody directed against a cell surface marker on B cells.  
     
     
         28 . The method of  claim 27 , wherein the onc protein has the amino acid sequence of SEQ ID NO: 1.  
     
     
         29 . The method of  claim 27 , wherein the onc protein is produced by recombinant means.  
     
     
         30 . The method of  claim 29 , wherein the onc protein has the amino acid sequence of SEQ ID NO:3.  
     
     
         31 . The method of  claim 29 , wherein the onc protein is encoded by a nucleic acid molecule identified as SEQ ID NO:2.  
     
     
         32 . The method of  claim 27 , wherein the cell surface marker is CD22.  
     
     
         33 . A method of killing malignant cells bearing a CD74 cell surface marker comprising contacting cells to be killed with a selective cytotoxic reagent comprising an onc protein having measurable ribonucleolytic activity joined to an antibody directed against CD74.  
     
     
         34 . The method of  claim 33 , wherein the cells to be killed are selected from the group consisting of neuroblastoma, melanoma and myeloma.