What is the FDA position on unknown risks in the risk/benefit analysis?
A. When evaluating any clinical protocol using an experimental biologic, FDA will weigh the risks from the product to the patient in terms of the potential benefit to the patients. Where the risks are known, appropriate safeguards are put into place to enhance patient safety. Where the risks are unknown, FDA may use its own expertise to devise preclinical studies that may reveal unexpected or theoretical hazards. FDA will also use its own or other government advisory committees to draw in pertinent expertise and discuss the potential hazards in public. FDA, for example, has used this process to discuss and devise appropriate safeguards for xenotransplantation and for gene therapy trials. FDA will integrate the advice and results of preclinical testing to formulate as safe a trial as can be done with current knowledge. FDA also will not hesitate to modify or halt a trial should new information be discovered that bears on patient safety. One example was the FDA response to an unexpected
