Methods and compositions for targeting proteins across the blood brain barrier

Abstract

Disclosed are methods and compositions for targeting therapeutic proteins to the brain. Methods and compositions of the invention involve associating an IGF moiety with a therapeutic protein in order to target the therapeutic protein to the brain. Soluble fusion proteins that include an IGF targeting moiety are transported to neural tissue in the brain from blood. Methods and compositions of the invention include therapeutic applications for treating lysosomal storage diseases. The invention also provides nucleic acids and cells for expressing IGF fusion proteins.

1 - 6 . (canceled)  
     
     
         7 . A method for targeting a therapeutic to lysosomes of cells in the central nervous system, the method comprising the step of administering a targeted therapeutic comprising: (i) a therapeutic agent that is therapeutically active in a lysosome and (ii) means for traversing the blood-brain barrier.  
     
     
         8 . The method of  claim 7 , wherein the means for traversing the blood-brain barrier comprises an insulin-like growth factor (IGF) moiety.  
     
     
         9 . The method of  claim 8 , wherein the IGF moiety is an intact IGF-I protein.  
     
     
         10 . The method of  claim 8 , wherein the IGF moiety comprises at least one of the A, B, C, or D domains, or the C-terminal region or a portion thereof, of either IGF-I or IGF-II.  
     
     
         11 . The method of  claim 7 , wherein the means for traversing the blood-brain barrier comprises a polypeptide sufficiently duplicative of IGF-II such that it binds an extracellular domain of human cation-independent mannose-6-phosphate/IGF-II receptor.  
     
     
         12 . The method of  claim 7 , wherein the therapeutic agent is a lysosomal enzyme.  
     
     
         13 . A method for targeting a therapeutic to lysosomes of cells of the central nervous system, the method comprising the step of administering a targeted therapeutic to the patient, wherein the targeted therapeutic comprises a therapeutic agent that is therapeutically active in lysosome and a targeting moiety comprising a polypeptide comprising a sequence sufficiently duplicative of at least one of the A, B, C, or D domains, or the C-terminal region or a portion thereof, of human IGF-I to be targeted to the central nervous system.  
     
     
         14 . The method of  claim 13 , wherein the targeting moiety comprises a mutein of the A domain of human IGF-I in which amino acids 55 and 56 are changed.  
     
     
         15 . The method of  claim 14 , wherein amino acids 55 and 56 of human IGF-I are changed to hydrophobic amino acids.  
     
     
         16 . The method of  claim 15 , wherein amino acids 55 and 56 are changed to Ala and Leu, respectively.  
     
     
         17 . The method of  claim 13 , wherein the targeting moiety comprises a polypeptide sufficiently duplicative of IGF-II such that it binds an extracellular domain of human cation-independent mannose-6-phosphate IGF-II receptor.  
     
     
         18 . The method of  claim 13 , wherein the therapeutic agent is a lysosomal enzyme.  
     
     
         19 . A method for targeting a therapeutic to lysosomes of cells of the central nervous system, the method comprising the step of administering a targeted therapeutic to a patient, wherein the targeted therapeutic comprises a therapeutic agent that is therapeutically active in a human lysosome and 
 a targeting moiety comprising a polypeptide comprising a sequence of human IGF-I or a mutein of the sequence of human IGF-I, wherein the sequence is selected from a group consisting of: 
 (i) amino acids 1 to 25 of human IGF-I;  
 (ii) amino acids 25 to 40 of human IGF-I;  
 (iii) amino acids 40 to 65 of human IGF-I; and  
 (iv) amino acids 65 to 70 of human IGF-I.  
   
     
     
         20 . The method of  claim 19 , wherein targeting moiety comprises a mutein of the sequence of amino acids 1 to 25 of human IGF-I, in which amino acid 24 is changed to Leu.  
     
     
         21 . The method of  claim 19 , wherein targeting moiety comprises a mutein of the sequence of amino acids 1 to 25 of human IGF-I, in which amino acids 1-3 are deleted.  
     
     
         22 . The method of  claim 19 , wherein targeting moiety comprises a mutein of the sequence of amino acids 40 to 65 of human IGF-I, in which amino acid 60 is changed to Leu.  
     
     
         23 . The method of  claim 19 , wherein targeting moiety comprises a mutein of the sequence of amino acids 40 to 65 of human IGF-I, in which amino acids 55 and 56 are changed to hydrophobic amino acids.  
     
     
         24 . The method of  claim 19 , wherein targeting moiety comprises a mutein of the sequence of amino acids 40 to 65 of human IGF-I, in which amino acids 55 and 56 are changed to Ala and Leu, respectively.  
     
     
         25 . The method of  claim 19 , wherein the targeting moiety comprises a polypeptide sufficiently duplicative of IGF-II such that it binds an extracellular domain of human cation-independent mannose-6-phosphate/IGF-II receptor.  
     
     
         26 . The method of  claim 19 , wherein the therapeutic agent is a lysosomal enzyme.