A suicide gene therapy combining the improvement of cyclophosphamide tumor cytotoxicity and the development of an anti-tumor immune response.
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.
Walid
W
Touati
Thi
T
Tran
Johanne
J
Seguin
Monique
M
Diry
Jean-Pierre
JP
Flinois
Claude
C
Baillou
Geraldine
G
Lescaille
Francois
F
Andre
Eric
E
Tartour
Francois M
FM
Lemoine
Philippe
P
Beaune
INSERM UMR-S1147, 45 rue des Saints Peres, 75006 Paris, France. isabelle.waziers@parisdescartes.fr.
Isabelle
I
de Waziers
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols; D045744:Cell Line, Tumor; D003520:Cyclophosphamide / Q000494:pharmacology*; D005260:Female; D041722:Genes, Transgenic, Suicide; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D008175:Lung Neoplasms / Q000188:drug therapy / Q000628:therapy; D051379:Mice; D008810:Mice, Inbred C57BL; D009251:NADPH-Ferrihemoprotein Reductase / Q000235:genetics / Q000378:metabolism; D011355:Prodrugs / Q000494:pharmacology
D000970:Antineoplastic Agents; D011355:Prodrugs; D003520:Cyclophosphamide; D009251:NADPH-Ferrihemoprotein Reductase