Systemic p53 gene therapy of cancer with immunolipoplexes targeted by anti-transferrin receptor scFv

Background: A long-standing goal in genetic therapy for cancer is a systemi c gene delivery system that selectively targets tumor cells, including meta stases. Here we describe a novel cationic immunolipoplex system that shows high in vivo gene transfer efficiency and antitumor efficacy when used for systemic p53 gene therapy of cancer. Materials and Methods: A cationic immunolipoplex incorporating a biosynthet ically lipid-tagged, anti-transferrin receptor single-chain antibody (TfRsc Fv), was designed to target tumor cells both in vitro and in vivo. A human breast cancer metastasis model was employed to evaluate the in vivo efficac y of systemically administered, TfRscFv-immunolipoplex-mediated, p53 gene t herapy in combination with docetaxel. Results: The TfRscFv-targeting cationic immunolipoplex had a size of 60-100 nm, showed enhanced tumor cell binding, and improved targeted gene deliver y and transfection efficiencies, both in vitro and in vivo. The p53 tumor s uppressor gene was not only systemically delivered by the immunolipoplex to human tumor xenografts in nude mice but also functionally expressed. In th e nude mouse breast cancer metastasis model, the combination of the p53 gen e delivered by the systemic administration of the TfRscFv-immunolipoplex an d docetaxel resulted in significantly improved efficacy with prolonged surv ival. Conclusions: This is the first report using scFv-targeting immunolipoplexes for systemic gene therapy. The TfRscFv has a number of advantages over the transferrin (Tf) molecule itself: (1) scFv has a much smaller size than Tf producing a smaller immunolipoplex giving better penetration into solid tu mors; (2) unlike Tf, the scFv is a recombinant protein, not a blood product ; (3) large scale production and strict quality control of the recombinant scFv, as well as scFv-immunolipoplex, are feasible. The sensitization of tu mors to chemotherapy by this tumor-targeted and efficient p53 gene delivery method could lower the effective dose of the drug, correspondingly lesseni ng the severe side effects, while decreasing the possibility of recurrence. Moreover, this approach is applicable to both primary and recurrent tumors , and more significantly, metastatic disease. The TfRscFv-targeting of cati onic immunolipoplexes is a promising method of tumor targeted gene delivery that can be used for systemic gene therapy of cancer with the potential to critically impact the clinical management of cancer.