Regulatory considerations on new adjuvants and delivery systems.

New and improved vaccines and delivery systems are increasingly being developed for prevention, treatment and diagnosis of human diseases. Prior to their use in humans, all new biological products must undergo pre-clinical evaluation. These pre-clinical studies are important not only to establish the biological properties of the material and to evaluate its possible risk to the public, but also to plan protocols for subsequent clinical trials from which safety and efficacy can be evaluated. For vaccines, evaluation in pre-clinical studies is particularly important as information gained may also contribute to identifying the optimum composition and formulation process and provide an opportunity to develop suitable indicator tests for quality control. Data from pre-clinical and laboratory evaluation studies, which continue during clinical studies, is used to support an application for marketing authorisation. Addition of a new adjuvant and exploration of new delivery systems for vaccines presents challenges to both manufacturers and regulatory authorities. Because no adjuvant is licensed as a medicinal product in its own right, but only as a component of a particular vaccine, pre-clinical and appropriate toxicology studies need to be designed on a case-by-case basis to evaluate the safety profile of the adjuvant and adjuvant/vaccine combination. Current regulatory requirements for the pharmaceutical and pre-clinical safety assessment of vaccines are insufficient and initiatives are in place to develop more specific guidelines for evaluation of adjuvants in vaccines.