A Suicide Gene Therapy Combining the Improvement of Cyclophosphamide Tumor Cytotoxicity and the Development of an Anti-Tumor Immune Response

Title:A Suicide Gene Therapy Combining the Improvement of Cyclophosphamide Tumor Cytotoxicity and the Development of an Anti-Tumor Immune Response

Volume: 14 Issue: 3

Author(s): Walid Touati, Thi Tran, Johanne Seguin, Monique Diry, Jean-Pierre Flinois, Claude Baillou, Geraldine Lescaille, Francois Andre, Eric Tartour, Francois M. Lemoine, Philippe Beaune and Isabelle de Waziers

Affiliation:

Keywords: Cytochrome P450 2B6, lentivirus, cyclophosphamide, lung cancer.

Abstract: Gene-directed enzyme prodrug therapy (GDEPT) consists in targeted delivery to tumor cells of a suicide gene responsible for in situ conversion of a prodrug into cytotoxic metabolites. One of the major limitations of this strategy in clinical application was the poor prodrug activation capacity of suicide gene. We built a highly efficient suicide gene capable of bioactivating the prodrug cyclophosphamide (CPA) by fusing a CYP2B6 triple mutant with NADPH cytochrome P450 reductase (CYP2B6TM-RED). Expression of this fusion gene via a recombinant lentivirus (LV) vector converted resistant human (A549) and murine (TC1) pulmonary cell lines into CPA-susceptible cell lines. We tested the efficiency of our GDEPT strategy in C57Bl/6 immunocompetent mice, using TC1 cells expressing the HPV-16 E6/E7 oncoproteins. In mice bearing tumors composed only of TC1-CYP2B6TM-RED cells, four CPA injections (140 mg/Kg once a week) completely eradicated the tumors for more than two months. Tumors having only 25% of TC1-CYP2B6TM-RED cells were also completely eradicated by five CPA injections, demonstrating a major in vivo bystander effect. Moreover, surviving mice were rechallenged with parental TC1 cells. The tumors regressed spontaneously 7 days after cell inoculation or grew more slowly than in control naive mice due to a strong immune response mediated by anti-E7CD8⁺T cells. These data suggest that combining the CYPB6TM-RED gene with CPA may hold promise as a highly effective treatment for solid tumors in humans.

Cite this article as:

Touati Walid, Tran Thi, Seguin Johanne, Diry Monique, Flinois Jean-Pierre, Baillou Claude, Lescaille Geraldine, Andre Francois, Tartour Eric, Lemoine M. Francois, Beaune Philippe and Waziers de Isabelle, A Suicide Gene Therapy Combining the Improvement of Cyclophosphamide Tumor Cytotoxicity and the Development of an Anti-Tumor Immune Response, Current Gene Therapy 2014; 14 (3) . https://dx.doi.org/10.2174/1566523214666140424152734