RESUMO
The potential utility of tumour-selective 5-fluorouracil treatment using attenuated Salmonella serovar typhimurium recombinant for cytosine deaminase (TAPET-CD) has been documented in experimental settings. The present data demonstrate that in vivo (19)F-magnetic resonance spectroscopy measurements allow the outcome prediction of this prokaryotic-based therapy, demonstrating the necessity of non-invasive real-time imaging techniques for treatment monitoring.
Assuntos
Antineoplásicos/metabolismo , Citosina Desaminase/uso terapêutico , Flucitosina/metabolismo , Fluoruracila/metabolismo , Terapia Genética/métodos , Neoplasias Experimentais/terapia , Animais , Antineoplásicos/análise , Antineoplásicos/uso terapêutico , Western Blotting , Cromatografia em Camada Fina , Citosina Desaminase/genética , Feminino , Flucitosina/análise , Flucitosina/uso terapêutico , Fluoruracila/análise , Fluoruracila/uso terapêutico , Vetores Genéticos , Humanos , Espectroscopia de Ressonância Magnética , Camundongos , Pró-Fármacos/análise , Pró-Fármacos/metabolismo , Pró-Fármacos/uso terapêutico , Salmonella typhimurium/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
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.