Repeated cycles of Clostridium-directed enzyme prodrug therapy result in sustained antitumour effects in vivo

• Published in: British journal of cancer Vol. 95; no. 9; pp. 1212 - 1219
• Main Authors: Theys, J, Pennington, O, Dubois, L, Anlezark, G, Vaughan, T, Mengesha, A, Landuyt, W, Anné, J, Burke, P J, Dûrre, P, Wouters, B G, Minton, N P, Lambin, P
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 06.11.2006
• Subjects: Animals; Antineoplastic Agents - metabolism; Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; Aziridines - metabolism; Aziridines - pharmacology; Aziridines - therapeutic use; Bacteria; Cancer research; Cancer therapies; Cell Line; Cell Survival - drug effects; Clostridium; Clostridium - genetics; Colorectal Neoplasms - genetics; Colorectal Neoplasms - pathology; Colorectal Neoplasms - therapy; Combined Modality Therapy; Dose-Response Relationship, Drug; Enzymes; Female; Genetic engineering; Genetic Therapy - methods; Genetic Vectors - administration & dosage; Genetic Vectors - genetics; HCT116 Cells; Humans; Hypoxia; Kinases; Medical research; Mice; Mice, Inbred Strains; Mice, Nude; Nitroreductases - genetics; Nitroreductases - isolation & purification; Nitroreductases - metabolism; Prodrugs - metabolism; Prodrugs - pharmacology; Prodrugs - therapeutic use; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Spores, Bacterial - genetics; Translational Therapeutics; Treatment Outcome; Tumors; Viral infections; Xenograft Model Antitumor Assays; Belgium; United Kingdom > UK
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/sj.bjc.6603367

The unique properties of the tumour microenvironment can be exploited by using recombinant anaerobic clostridial spores as highly selective gene delivery vectors. Although several recombinant Clostridium species have been generated during the past decade, their efficacy has been limited. Our goal was to substantially improve the prospects of clostridia as a gene delivery vector. Therefore, we have assessed a series of nitroreductase (NTR) enzymes for their capacity to convert the innocuous CB1954 prodrug to its toxic derivative. Among the enzymes tested, one showed superior prodrug turnover characteristics. In addition, we established an efficient gene transfer procedure, based on conjugation, which allows for the first time genetic engineering of Clostridium strains with superior tumour colonisation properties with high success rates. This conjugation procedure was subsequently used to create a recombinant C. sporogenes overexpressing the isolated NTR enzyme. Finally, analogous to a clinical setting situation, we have tested the effect of multiple consecutive treatment cycles, with antibiotic bacterial clearance between cycles. Importantly, this regimen demonstrated that intravenously administered spores of NTR-recombinant C. sporogenes produced significant antitumour efficacy when combined with prodrug administration.