INTRODUCTION: The overexpression of transferrin (Tf) receptors on cancer cells 
renders them a useful target for the delivery of small-molecule drugs and 
nucleic acid therapeutics to these cells. This approach could alleviate the 
non-target effects of the drugs.
AREAS COVERED: The function of the Tf receptor, the development of Tf-lipid-DNA 
complexes (Tf lipoplexes), therapeutic use of lipoplexes and polymer-DNA 
complexes (poylplexes), and the therapeutic use of Tf-lipoplexes and 
anti-Tf-receptor antibody-lipoplexes are outlined. The literature search for 
this review was based primarily on the terms 'lipoplexes,' 'lipopolyplexes' 
'transferrin,' 'transferrin receptor,' and 'gene therapy.' However, the review 
was not intended to be comprehensive.
EXPERT OPINION: Complexes of Tf with cationic liposomes and nucleic acids, or 
liposomes with covalently attached Tf or anti-transferrin receptor antibodies 
have been used for the delivery of therapeutic genes, antisense 
oligodeoxynucleotides, and short interfering RNA. Although such targeted 
nonviral delivery vehicles may benefit from further enhancement of their 
efficacy, current achievements at the cell culture and animal model level should 
be translated into clinical applications, restricted initially to localized 
delivery into accessible tissues to avoid potential systemic side-effects and 
non-target delivery.