Mononuclear phagocytes in therapeutic drug delivery

Abstract

The invention relates to the exploitation of the migratory behaviour of mononuclear phagocytes with a view to targeting therapeutic drug delivery. The invention therefore concerns the attachment or incorporation of a therapeutic agent to or into a mononuclear phagocyte and the subsequent migration of the mononuclear phagocyte to a target area.

1 . A mononuclear phagocyte modified to comprise at least one regulatable element operably linked to at least one nucleotide sequence of interest (NOI), wherein said regulatable element is capable of regulating expression of said NOI in a tumour site and is selected from a hypoxia regulatable element, an ischemic regulatable element and a stress regulatable element. 
     
     
         2 . The mononuclear phagocyte according to  claim 1  wherein the mononuclear phagocyte comprises a binding agent capable of binding to a cell surface element of the mononuclear phagocyte. 
     
     
         3 . The mononuclear phagocyte according to  claim 2  wherein the binding agent comprises a mannosylated poly-L-lysine ligand. 
     
     
         4 . The mononuclear phagocyte according to  claim 2  wherein the binding agent comprises a viral vector for internalising the regulatable element into the mononuclear phagocyte. 
     
     
         5 . The mononuclear phagocyte according to  claim 1  wherein the NOI is incorporated into the genome of the mononuclear phagocyte. 
     
     
         6 . The mononuclear phagocyte according to  claim 4  wherein the viral vector is a lentiviral vector. 
     
     
         7 . The mononuclear phagocyte according to  claim 1  wherein the mononuclear phagocyte further comprises an NOI encoding HIF1-alpha or a tetracycline repressor protein. 
     
     
         8 . The mononuclear phagocyte according to  claim 1  wherein the at least one NOI encodes a pro-drug activation enzyme. 
     
     
         9 . A construct comprising at least one regulatable element operably linked to at least one nucleotide sequence of interest (NOI), wherein said regulatable element is selected from a hypoxia regulatable element, an ischemic regulatable element and a stress regulatable element, and wherein the construct is coupled to a binding agent that is capable of selective binding to a cell surface element of a mononuclear phagocyte. 
     
     
         10 . The construct according to  claim 9  wherein the regulatable element is an HRE element. 
     
     
         11 . The construct according to  claim 9  or  claim 10  wherein the binding agent comprises a ligand adapted to bind to the cell surface element. 
     
     
         12 . The construct according to  claim 9  or  claim 10  wherein the binding agent comprises a viral vector for internalising the regulatable element into a mononuclear phagocyte. 
     
     
         13 . The construct according to  claim 12  wherein the viral vector is selected from the group consisting of an adenoviral vector and a lentiviral vector. 
     
     
         14 . A method for internalising a regulatable element into a mononuclear phagocyte wherein the regulatable element is selected from a hypoxia regulatable element, an ischemic regulatable element and a stress regulatable element and the method comprises:
 providing a mononuclear phagocyte ex vivo; and   exposing the mononuclear phagocyte to a construct as defined in any one of  claims 9  or  10  under conditions sufficient to internalise the construct into the mononuclear phagocyte.   
     
     
         15 . A composition comprising a mononuclear phagocyte according to  claim 1  optionally admixed with a pharmaceutically acceptable diluent, excipient or carrier. 
     
     
         16 . A composition comprising a construct according to  claim 9  optionally admixed with a pharmaceutically acceptable diluent, excipient or carrier. 
     
     
         17 . A mononuclear phagocyte comprising an NOI encoding a p450 enzyme wherein the NOI has been internalised into the mononuclear phagocyte by an adenoviral vector; and wherein the NOI encoding the p450 enzyme is operably linked to
 a hypoxia response element (HRE); such that the p450 enzyme is expressed under suitable hypoxic conditions.   
     
     
         18 . The mononuclear phagocyte according to  claim 8  wherein the pro-drug activation enzyme is a p450 enzyme. 
     
     
         19 . The mononuclear phagocyte according to  claim 18  wherein the p450 enzyme, is a CYP2B6 p450 enzyme. 
     
     
         20 . The construct according to  claim 11  wherein the ligand is a mannosylated poly-L-lysine.