Gene therapy is a medical approach that treats or prevents disease by correcting the underlying genetic problem. It involves altering the genes inside a persons bodys cells to treat or stop disease. Gene therapy can work by several mechanisms, including replacing a disease-causing gene with a healthy copy of the gene, inactivating a disease-causing gene that is not functioning properly, or introducing a new or modified gene into the body to help treat a disease. Gene therapy products are being studied to treat diseases including cancer, genetic diseases, and infectious diseases.

Gene therapy can be used to modify cells inside or outside the body. When gene therapy is used to modify cells inside the body, a doctor will inject the vector carrying the gene directly into the patient. When gene therapy is used to modify cells outside the body, doctors take blood, bone marrow, or another tissue, and separate out specific cell types in the lab. The vector containing the desired gene is introduced into these cells. The cells are later injected into the patient, where the new gene is used to produce the desired effect.

Gene therapy holds promise for treating a wide range of diseases, such as cancer, cystic fibrosis, heart disease, diabetes, hemophilia, and AIDS. Currently, in the United States, gene therapy is available only as part of a clinical trial. Gene therapy products are biological products regulated by the FDA’s Center for Biologics Evaluation and Research (CBER) . Before a gene therapy can be marketed for use in humans, the product must be tested in clinical studies for safety and effectiveness so FDA scientists can consider whether the risks of the therapy are acceptable considering the potential benefits.