A husband and wife research team in the UK have developed a new technique for treating cancer. Professor David Hirst and Dr. Tracey Robson of the University of Ulster's School of Biomedical Sciences are using one of the most important genes in the human body to combat the disease by injecting it directly into tumors. They have been given a grant of £70,000 by the Cancer Research Campaign, and have been developing the technique for three years. They hope to start clinical trials within 18 months.
The nitric oxide gene, which is produced at low levels to control blood pressure, has been coupled with a molecular switch activated when exposed to radiation. The method enables tumors to be destroyed without damaging healthy cells, an effect of current treatments.
One of the most serious problems of treating tumors is that the most damaged cells do not hold oxygen, which makes them resistant to radiotherapy and chemotherapy. Releasing nitric oxide inside the tumor allows oxygen to reach the cells.
There are other benefits. The gene remains active for 48 hours, reducing the frequency of radiation treatment, and it is highly toxic when produced in large quantities, which kills cells inside the tumor. It also prevents the growth of blood vessels, which stops the tumor from growing and recovering after treatment.
The researchers believe their technique can be used to combat a number of different forms of cancer, which kills more than 150,000 people a year in the United Kingdom. The initial clinical trials will be with patients in the late stages of some of the most accessible forms of cancer, including lung, breast and prostate.
Other researchers are developing drugs to perform a similar function, but they are administered orally and contain chemicals. The use of other genes is also being studied, but most are aimed at tackling specific forms of cancer. Nobody else is attempting to use nitric oxide, the researchers say.
The scientists have been encouraged by tests carried out on mice. They found that an untreated tumor killed the mice within a week. When treated by a single dose of radiation, it took 11 days. When a single dose of nitric oxide was injected into the tumor before radiotherapy, it took 30 days to reach the same size.
Professor Hirst and Dr. Robson believe further injections will slow the process even more and eventually destroy the tumor.
07-May-2001
