Soluble polypeptide fractions of the LAG-3 protein, production method, therapeutic composition, anti-idiotype antibodies

Abstract

Soluble polypeptide fraction consisting of all or part one of at least one of the four immunoglobulin-type extracellular LAG-3 protein domains (amino acids 1-159, 160-230 239, 240-330 and 331-412 of the SEQ ID NO:1 sequence) or consisting of one peptide sequence derived from these domains by replacement, addition or deletion of one or more amino acids. The fraction of the invention has a specificity at least equal to that of LAG-3 in relation to its ligand.

We claim:  
     
       1. A soluble polypeptide fraction consisting of at least one of the 4 immunoglobulin type extra-cellular domains of the LAG-3 protein (amino acids 1 to 4, 5 to 239, 240 to 330 and 331 to 412 of sequence SEQ ID NO:1), wherein one or more arginine (Arg) residues at positions 73, 75 and 76 of SEQ ID NO:1 are substituted with glutamic acid (Glu) and said at least one extra-cellular domain of LAG-3 protein is optionally fused to a supplementary peptide sequence as a fusion protein. 
     
     
       2. A soluble polypeptide fraction  according to claim  1   11 , further bound to a toxin or a radioisotope. 
     
     
       3. A soluble polypeptide fraction according to  claim 1 , further bound to a toxin or a radioisotope wherein said supplementary peptide sequence is present and comprises a portion of an immunoglobulin. 
     
     
       4. A soluble polypeptide fraction  according to claim  3   13 , wherein said supplementary peptide sequence comprises a portion of an immunoglobulin of IgG4 isotype. 
     
     
       5. A method for producing the soluble polypeptide fraction  of claim  1   11 , which soluble polypeptide fraction  further comprises a portion of an immunoglobulin, comprising the steps of : 
       inserting a DNA molecule comprising a fusion of fragments of cDNA coding for the polypeptide regions corresponding to LAG-3 or derived from LAG3 with cDNA coding for the portion of the immunoglobulin;  
       transfecting the DNA molecule into a host expression system; and  
       producing the soluble polypeptide fraction  by expression in the host.  
     
     
       6. A soluble polypeptide fraction consisting of at least one of four immunoglobulin-type extracellular domains of LAG-3 protein corresponding to amino acid residues 1-4, 5-239, 240-330, and 331-412 of SEQ ID NO:1, fused to a supplementary peptide sequence as a fusion protein. 
     
     
       7. A soluble polypeptide fraction according to  claim 6 , further bound to a toxin or a radioisotope. 
     
     
       8. A soluble polypeptide fraction according to  claim 6 , further bound to a toxin or a radioisotope wherein said supplementary peptide sequence comprises a portion of an immunoglobulin. 
     
     
       9. A soluble polypeptide fraction according to  claim 8 , wherein said supplementary peptide sequence comprises a portion of an immunoglobulin of IgG4 isotype. 
     
     
       10. A method for producing the soluble polypeptide fraction of  claim 6 , which soluble polypeptide fraction further comprises a portion of an immunoglobulin, comprising the steps of: 
       inserting a DNA molecule comprising a fusion of fragments of cDNA coding for the polypeptide regions corresponding to LAG-3 with cDNA coding for the portion of the immunoglobulin;  
       transfecting the DNA molecule into a host expression system; and  
       producing the soluble polypeptide fraction by expression in the host.  
     
     
       11. A soluble polypeptide comprising a first immunoglobulin type extracellular domain of LAG-   3  protein  ( amino acid residues  1 - 159  of SEQ ID NO: 1   ),  wherein one or more arginine  ( Arg )  residues at positions  73 ,  75  and  76  of SEQ ID NO: 1  are substituted with glutamic acid  ( Glu ). 
     
     
       12. A soluble polypeptide according to  claim 11 , further comprising a supplementary peptide sequence fused to said first extracellular domain of LAG-   3  protein as a fusion protein.   
     
     
       13. A soluble polypeptide according to  claim 12 , wherein said supplementary peptide sequence comprises a portion of an immunoglobulin. 
     
     
       14. A soluble polypeptide according to  claim 11 , wherein said first extracellular domain of LAG-   3  protein is fused to one or more additional immunoglobulin type extracellular domains of LAG -   3  protein selected from the group consisting of amino acid residues  160 - 239 ,  240 - 330 , and  331 - 412  of SEQ ID NO: 1 .   
     
     
       15. A soluble polypeptide according to  claim 14 , further comprising a supplementary peptide sequence fused to either said first extracellular domain of LAG-   3  protein or one of said one or more additional extracellular domains of LAG -   3  protein.