The goal of gene therapy is to replace missing or defective genes with healthy ones. Since 1990, more than 4,000 people have received gene therapy, most with the same gene delivery method. Mild immune system responses are the most common side effects. The delivery vehicle, or vector, used on Gelsinger is an adenovirus, which is a cold virus modifed to carry genes into cells. The modified virus does not cause a cold, but it retains the machinery for getting itself inside cells.
Patients tend to react to proteins on the virus' shell.
The review of studies using adenovirus vectors is intended to reveal side effects that may have been unreported or overlooked, if they exist, says Amy Patterson, director of the Office of Recombinant DNA Activities at the National Institutes of Health. This is prompting a very careful review by the scientists involved in the study, federal investigators and others in the field. Additional oversight of gene therapy trials does appear necessary for now, she added. Human gene therapy studies are approved by internal review boards at institutions where studies are done and by the Food and Drug Administration. The RAC may hold public hearings on novel studies, but it does not have authority to approve or reject a study.