SINGLE CHAIN Fc FUSION PROTEINS

Abstract

The present invention provides novel, single chain Fc fusion proteins having improved properties. The invention provides single chain fusions of soluble proteins fused to the Fc region of an immunoglobulin via a novel linker comprising a constant region of an immunoglobulin light chain linked to a CH1 constant region of an immunoglobulin heavy chain. This novel linker confers favorable properties on the Fc fusion proteins of the invention such as improved bioactivity and increased half-life as compared to non-Fc fusion counterparts or as compared to prior art Fc fusion proteins. The novel Fc fusion protein scaffold as described herein may be designed to include soluble proteins of interest capable of binding or interacting with any target of interest. Preferably, the Fc fusion protein of the invention is a dimer. The dimer preferably forms via a disulfide bond between free cysteine residues in the hinge region of two monomeric Fc fusion proteins of the invention.

1 . A single chain fusion protein having the following arrangement from amino-terminus to carboxy-terminus:
   X-L1-HINGE-Fc   wherein,   X is a soluble protein or any active fragment or derivative thereof;   L1 is a linker having the following arrangement from amino-terminus to carboxy-terminus:
   L2-CL-L3-CH1-L4 or L2-CH1-L3-CL-L4 
   wherein,
 L2 and L4 are independently polypeptide linkers or are independently absent; 
 L3 is a polypeptide linker; 
 CL is a constant region polypeptide of an immunoglobulin light chain; and 
 CH1 is a constant region polypeptide from a CH1 domain of an immunoglobulin heavy chain; 
 HINGE is a hinge sequence of an immunoglobulin or is absent with the proviso that if HINGE is absent, L4 is present; and 
 Fc is the carboxy-terminus of an immunoglobulin or any active fragment or derivative thereof. 
   
     
     
         2 . The fusion protein of  claim 1 , wherein CL, CH1, HINGE and Fc are at least 90% identical to the CL, CH1, hinge and Fc regions respectively of human IgG1. 
     
     
         3 . The fusion protein of  claim 1 , wherein X is Factor IX, TNFR2 or IL1Ra or any active fragment or derivative thereof. 
     
     
         4 . The fusion protein of  claim 1 , wherein L3 is a polypeptide linker having the amino acid sequence (GGGGS)n wherein n is 1-5. 
     
     
         5 . The fusion protein of  claim 1 , wherein L2 is present and is a polypeptide linker having the amino acid sequence (GGGGS)n wherein n is 1-5. 
     
     
         6 . The fusion protein of  claim 1 , wherein L4 is present and is a polypeptide linker having the amino acid sequence (GGGGS)n wherein n is 1-5. 
     
     
         7 . The fusion protein of  claim 1 , wherein HINGE and L2 are present and L4 is absent. 
     
     
         8 . The fusion protein of  claim 1 , wherein HINGE, L2 and L4 are present. 
     
     
         9 . The fusion protein of  claim 1 , wherein HINGE is absent and L4 is present. 
     
     
         10 . The fusion protein of  claim 1 , wherein HINGE is absent and L2 and L4 are present. 
     
     
         11 . A dimerized complex comprising the fusion protein of  claim 1 . 
     
     
         12 . The dimerized complex of  claim 11 , wherein the dimerized complex is a homodimeric complex. 
     
     
         13 . The fusion protein of  claim 1 , wherein X comprises a soluble protein that has been modified by circular permutation. 
     
     
         14 . The fusion protein of  claim 13 , wherein X comprises circularly permuted IL-2. 
     
     
         15 . The fusion protein of  claim 13 , wherein X comprises circularly permuted IL-2 fused to IL-2Rα via an optional linker. 
     
     
         16 . The fusion protein of  claim 1 , wherein X is IFNβ. 
     
     
         17 . The fusion protein of  claim 1 , wherein X is IL-10, IL-2, IL-2Rα or fusions thereof, or IFNβ or any active fragment or derivatives thereof. 
     
     
         18 . The fusion protein of  claim 1 , wherein X is IL-10. 
     
     
         19 . A homodimeric complex of the fusion protein of  claim 18 . 
     
     
         20 . A method of treating auditory disorders, renal cell carcinoma, melanoma, psoriasis, fibrosis, depression, or inflammatory bowel disease (IBD) in a patient comprising administering to the patient a therapeutically effective amount of a fusion protein of  claim 18  or a homodimeric complex thereof.