Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Patent
1996-07-01
1999-09-28
Crouch, Deborah
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
4353201, 435325, 435455, 536 237, C12N 500, C12N 1500, C07H 2104
Patent
active
059586826
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to viral mediated gene therapy and its use in the treatment of tumours.
TECHNOLOGY BACKGROUND
A therapeutic approach termed "virus-directed enzyme prodrug therapy" (VDEPT) has been proposed as a method for treating tumour cells in patients using prodrugs. Tumour cells are targeted with a viral vector carrying a gene encoding an enzyme capable of activating a prodrug. The gene may be transcriptionally regulated by tissue specific promoter or enhancer sequences. The viral vector enters tumour cells and expresses the enzyme, in order that a prodrug is converted to an active drug only in the vicinity of the tumour cells (Huber et al, Proc. Natl. Acad. Sci. USA (1991) 88, 8039).
Although the VDEPT system enhances the concentrations of anti-tumour agent which may be delivered to the site of a tumour, there is still a need to enhance the specificity and efficiency of drug delivery.
The present invention addresses such problems by the use of a VDEPT viral vector which encodes for a nitroreductase.
SUMMARY OF THE INVENTION
The present invention therefore provides a system comprising:
(i) a viral vector comprising a nucleotide sequence encoding a nitroreductase, which nitroreductase is capable of converting a prodrug into a cytotoxic drug; and
(ii) a prodrug capable of being converted into an active drug by the nitroreductase encoded by the vector.
The invention also provides a kit which comprises a vector defined herein together with a prodrug as defined herein.
In another aspect, the invention provides a system as defined herein or a kit as defined herein for use in a method of treatment of the human or animal body, and in particular a method of treatment of tumours.
In a further aspect, the invention provides a method of treatment of tumours which comprises administering to an individual with a tumour (i) an effective amount of a vector as defined herein, and (ii) an effective amount of a prodrug capable of being converted to an active drug by the nitroreductase encoded by the vector.
In a further embodiment, the invention provides a method of ablating normal tissue which comprises administering to a human or animal body an effective amount of a vector as defined herein and an effective amount of a prodrug capable of being converted to an active drug by a nitroreductase encoded by the vector.
In a further embodiment the invention provides a method for killing cells in an animal or human wherein a viral vector comprising a nucleic acid sequence encoding a nitroreductase which converts a prodrug into a cytotoxic drug is introduced into animal or human cells in vitro so that nitroreductase is produced in the cells, the cells are administered to an animal or human, and a prodrug is then administered to the animal or human, where it is converted into a cytotoxic agent in nitroreductase-containing cells of the animal.
In a further embodiment the invention provides a product containing a viral vector as defined herein and a prodrug as defined herein as a combined preparation for simultaneous, separate or sequential use in the treatment of tumours or the ablation of tissue.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1. Graph demonstrating the cytotoxicity achieved by the action of nitroreductase (NR) at various concentrations upon the N-4-nitrobenzyloxycarbonyl derivative (prodrug) of actinomycin D.
FIG. 2. Graph demonstrating the bystander effect and cytotoxicity achieved by CB 1954 administration to nitroreductase-transduced NIH3T3 cells as observed with a standard thymidine-incorporation assay. Results are plotted as the quantity of .sup.3 H-thymidine incorporation into live cells (10% decays/min) (Y-axis) versus the percentage of transduced cells in the sample population (X-axis).
FIG. 3. Two graphs comparing the nitroreductase/CB 1954 and thymidine kinase/gancyclovir enzyme/prodrug systems. FIG. 3a shows that arrest of NTR-expressing NIH3T3 cells does not affect the relative cytotoxicity of increasing quantities of CB 1954, whereas FIG. 3b shows that arrest of T
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Connors Thomas
Knox Richard
Sherwood Roger
Cancer Research Campaign - Technology Limited
Carroll Lawrence J.
Crouch Deborah
Schneller John W.
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