A new gene therapy trial has just started at Queen Elizabeth hospital, Birmingham,
Dr PETER SEARLE (Institute for Cancer Studies, University of Birmingham) told
the Conference. It is a phase 1 study in patients with liver cancer and involves
a VDEPT (virally delivered enzyme prodrug therapy) technique.
An adenovirus is used to deliver the gene for E coli nitroreductase enzyme.
This enzyme is able to activate a prodrug, CB1954, to produce a cytotoxic compound.
Dr Searle said that there were two parts to the study. In patients with operable
tumours, the viral vector would be injected into the tumour and the tumour would
then be removed for monitoring of gene expression. Later, the study would be
extended to include inoperable patients who would receive the IV prodrug after
the virus. The idea was that CB1954 would be activated at the tumour site and
exert its effects locally.
Dr Searle said that they were not aiming to cure patients at this stage but
were looking at safety issues and scientific end points regarding efficacy.
A gene therapy pharmacist had been employed to prepare the treatment. This work
was undertaken in a satellite pharmacy within the cancer centre at the hospital.
To avoid concerns about the use of a pharmacy isolator for viral preparation,
the pharmacist started at 7am so that the work was finished and the isolator
could be cleaned before routine pharmacy dispensing got under way.
Ms Sue Whitmarsh (head of oncology pharmacy, Queen Elizabeth hospital) told
The Journal that, in the absence of guidelines for working with genetically
modified viruses, the pharmacy had taken a pragmatic approach to safety precautions,
separating this work from the routine work. They had possibly gone “over
the top” since the virus used in the trial was a very low risk virus. The
long-term plan would be to have a dedicated facility for this type of work.
She said that the pharmacist’s job was to prepare dosages by reconstituting
the virus (which was produced by Cobra Therapeutics) and adding it to an infusion
bag.
Ms Whitmarsh said that, at present, there were few patient in the trial and
so the gene therapy pharmacist did not have to start work at 7am very often.