Both now take smaller doses of PEG-ADA to keep their disease under control. In studies of gene therapy for cancer, researchers are working to improve the body's natural ability to fight the disease or to make the cancer cells more sensitive to other kinds of treatment, such as chemotherapy. Injection of cancer cells with a gene that makes them more sensitive to treatment with an anticancer drug. Scientists hope that treatment with the drug will kill only the cells that contain the drug-sensitive gene. The MDR gene is used to make the stem cells more resistant to the side effects of the high doses of anticancer drugs.
Viruses can usually infect more than one type of cell.
Thus, when viral vectors are used to carry genes into the body, they might alter more than the intended cells. Another danger is that the new gene might be inserted in the wrong location in the DNA, possibly causing cancer or other damage. In addition, when DNA is injected directly into a tumor, or when a liposome delivery system is used, there is a slight chance that this DNA could unintentionally be introduced into reproductive cells, producing inheritable changes. However, scientists use animal testing and other precautions to identify and avoid these risks before any clinical trials are conducted in humans. Scientists need to identify easier and better ways to deliver genes to the body.