Interleukin 15 fusion protein for tumor targeting therapy

Abstract

Disclosed is a tumor-targeting fusion protein comprising at least (i) a IL-15 peptide or a variant or functional fragment thereof, (ii) a IL-15Rα polypeptide or a variant or functional fragment thereof, (iii) a Fc domain or a variant or functional fragment thereof, and (iv) a RGD polypeptide or a variant thereof. The fusion protein is preferably configured as RGD polypeptide-Fc domain-IL-15 polypeptide-IL-15Rα polypeptide. The tumor-targeting fusion proteins provided herein improves the anti-tumor effects of IL-15 and prolongs the half-life of IL-15, while targeting tumor sites and acting upon tumor cells. In addition, the fusion proteins are capable of being expressed at high efficiency and purified. The high efficiency of anti-tumor activity enables the fusion proteins to be an excellent candidate for tumor immunotherapy.

1 - 16 . (canceled) 
     
     
         17 . A method for treating cancer in a patient, comprising administering to the patient a fusion protein comprising an IL-15 peptide and an IL-15Rα peptide, wherein the IL-15Rα peptide has a deletion of the cysteine residue at the position that precedes SEQ ID NO:2 as in a full-length IL-15Rα. 
     
     
         18 . The method of claim  1 , wherein the IL-15 peptide and the IL-15Rα peptide are arranged from the N-terminus to the C-terminus in the fusion protein. 
     
     
         19 . The method of claim  1 , wherein the fusion protein further comprises an Fc domain. 
     
     
         20 . The method of claim  1 , wherein the IL-15Rα peptide comprises the amino acid sequence of SEQ ID NO:2. 
     
     
         21 . The method of claim  1 , wherein the IL-15 peptide comprises the amino acid sequence of SEQ ID NO:3.