Repeated cycles of Clostridium-directed enzyme prodrug therapy result in sustained antitumour effects in vivo.
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.
Theys
J
J
Department of Radiation Oncology (Maastro Lab), GROW Research Institute, University of Maastricht, UNS 50/23, PO Box 616, Maastricht 6200 MD, The Netherlands.
Pennington
O
O
Dubois
L
L
Anlezark
G
G
Vaughan
T
T
Mengesha
A
A
Landuyt
W
W
Anné
J
J
Burke
P J
PJ
Dûrre
P
P
Wouters
B G
BG
Minton
N P
NP
Lambin
P
P
D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D001388:Aziridines / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003013:Clostridium / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D003131:Combined Modality Therapy; D004305:Dose-Response Relationship, Drug; D005260:Female; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics; D045325:HCT116 Cells; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D009601:Nitroreductases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011355:Prodrugs / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013171:Spores, Bacterial / Q000235:genetics; D016896:Treatment Outcome; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D001388:Aziridines; D011355:Prodrugs; D011994:Recombinant Proteins; C100099:tretazicar; D009601:Nitroreductases