The cells normal DNA repair machinery then apparently replaced the mutation with the normal code thus permanently curing 10 to 20 percent of cells. The researchers still have to demonstrate that this technique works in human cells and in human bodies. In about half of lung cancer cases, a gene called p53 has mutated and thus falls to encode a protein that oversees programmed cell death. In the absence of this protein, Which helps to curb the growth of damaged or abnormal cells, cancer can gain a foothold. Replacing such defective p53 genes with fresh ones has shown promise against a variety of cancers in animal experiments and studies of a few patients.
Scientists now report further progress in such localized gene therapy.
By enlisting a virus to deliver p53 to tumor sites in 28 people with lung cancer, they temporarily stabilized or reversed the course of the cancer in more than half patients. The patients, average age 65, had lung cancer that was either inoperable or was no longer responding to radiation treatment or chemotherapy. The researchers injected the tumors with an adenovirus engineered to contain p53 genes. The virus was modified to prevent it from replicating and thus causing the upper respiratory infection that it might otherwise bring about. During the 6 months treatment period patients received one to six monthly injections of the modified virus.