Prospects for developmental immunotoxicity guidance and an update on ICH S8.
Potential adverse effects of drug exposure on the developing immune system had been a relatively neglected area of toxicology until fairly recently. However, with the recent regulatory emphasis on evaluation of drugs for use in pediatric patients, juvenile animal studies have been considered in much more detail than in the past in order to enable clinical trials. Assessment of immunotoxicity potential in these juvenile animal studies has been a natural consequence of drug development for pediatric patients. Unfortunately, the efforts to evaluate developmental immunotoxicity studies have not kept pace with the writing of an immunotoxicology guidance for the International Conference on Harmonisation of Technical Requirements for Registration of Human Pharmaceuticals (ICH). This document has recently reached Step 4 in the approval process: it is thus likely that juvenile animal studies for immunotoxicity would be recommended based on considerations enumerated in the ICH Safety Number 8 (S8) guidance. Sufficient flexibility exists in this document to cover the issue of developmental immunotoxicity. ICH S8 advocates a weight-of-evidence approach, which should be interpreted to indicate that immunotoxicity testing would be conducted based on identified cause(s) for concern rather than as a routine screening method. The presentation reflecting these issues, as presented to attendees of the Pharmaceutical Education Associates workshop on Innovative Methods and Applications for Risk Assessment in Pharmaceutical Development is summarized herein.