FDA Issues Draft Guidance on Immunotoxicity Studies

Manufacturers should begin nonclinical testing of all new investigational drugs to determine what, if any, impact they have on a patient's immune response, according to a new FDA draft guidance released under the auspices of the International Conference on Harmonisation.

The guidance states that drugmakers should use standard toxicity studies (STS) and additional immunotoxicity studies to determine a drug candidate's potential to produce immunosupression, a state of increased susceptibility to infections or the development of tumors.

If the findings from the STS indicate that there are signs of immunotoxicity, the FDA said the decision to conduct additional immunotoxicity testing should be determined by a weight-of-evidence review of the data.

The document also addresses the need for follow-up immunotoxicity tests. "Results of the entire data set should be evaluated as to whether sufficient data are available to reasonably determine the risk of immunotoxicity," according to the guidance. "If the overall risk-benefit analysis suggests that the risk of immunotoxicity is acceptable, then no follow-up testing might be called for." If changes are observed during immunotoxicity testing, however, the FDA recommends that the drugmaker conduct further studies.

The draft guidance, titled "S8 Immunotoxicity Studies for Human Pharmaceuticals," was published in the Federal Register Feb. 8. To view the guidance, go to http://www.fda.gov/OHRMS/DOCKETS/98fr/2005d-0022-gdl0001.pdf (http://www.fda.gov/OHRMS/DOCKETS/98fr/2005d-0022-gdl0001.pdf).