Challenges and lessons learned since implementation of the safety pharmacology guidance ICH S7A

The International Conference on Harmonization, Topic S7A guidance (ICH S7A) on safety pharmacology for human pharmaceuticals has been in effect for 3 years in Europe, the United States and Japan. Surveys of the pharmaceutical industry, regulatory agencies and the audience attending the 4th Annual Meeting of the Safety Pharmacology Society have helped identify and address areas of controversy, as well as those challenges that have emerged since implementation of the guidance worldwide. Overall, ICH S7A has been successfully implemented. The guidance provides for “Good Laboratory Practice” compliant “safety pharmacology core battery” of studies that are generally performed prior to first administration to humans. The approach is science-driven and specifies the use of robust and sophisticated in vitro and/or in vivo assays. There are, however, some areas that require further refinement/clarification such as the specifics of study design including the selection of dose/concentration, choice of species, modeling of the temporal pharmacodynamic changes in relation to pharmacokinetic profile of parent drug and major metabolites, use of an appropriate sample size, statistical power analysis as a means of demonstrating the sensitivity of the model system, testing of human-specific metabolites and demonstrating not only the model's sensitivity, but also its specificity for predicting adverse events in humans. There was also discussion of when these studies are needed in relation to the clinical development plan. Representatives from the pharmaceutical industry and regulatory agencies see the implementation of ICH S7A as a major step forward towards identifying the risk to Phase 1 and 2 volunteers and patients. It remains to be seen, however, whether and in what ways the ICH S7A-based strategy will contribute to the modification of the integrated risk assessment during the latter stages of clinical development or once drugs have been introduced to the marketplace.