Are Repeat-Dose Toxicity Studies Informative for Safety Assessment of Vaccine Candidates? A Survey of Vaccine Developers.

A BioSafe-sponsored survey investigated how vaccine companies (n = 12) perceive the value of the repeat-dose toxicity studies for safety assessment of vaccine candidates. As all major vaccine developers were part of the survey, it was considered representative for the industry practices up to 2022. Vaccine developers indicated that they see scientific value in performing repeat-dose toxicity studies with vaccines, especially when novel components (e.g., adjuvant) or technology is being used. However, a few (3/12) also indicated that repeat-dose toxicity studies could be replaced by a pharmacology study with additional toxicity parameters. For the majority of companies (9/12), findings from the repeat-dose toxicity studies never prevented or postponed a first-in-human (FIH) trial. In the remaining 3 companies, a total of 4 occurrences of postponement or prevention of clinical development occurred and in only 2 of these cases was the finding considered related to the vaccine. A platform approach has been successfully implemented for influenza vaccines already in 2016, and an outline of the regulatory requirements for a platform approach has been recently documented in the latest infectious disease mRNA-LNP vaccine guideline, as well as in the guidance on the development and licensure of COVID-19 vaccines presented by the FDA. Vaccine developers are seeking to extend this platform approach to the development of new vaccines, building on established technologies and using well-defined manufacturing processes. This approach could support reduction of animal use (a principle of 3Rs) while still providing reassurance of the nonclinical safety of these products.