The nonclinical toxicology studies are potent enough for identifying and characterizing the potentially toxic effects of both preventive and therapeutic vaccines. These allow the investigators in concluding that the vaccine trial is reasonably safe for proceeding ahead with the clinical investigation. The relevance of animal species, its strain, dosing schedule and route of vaccine administration help in evaluating time for end-points. The route of administration should be the exact one which is intended to be applied for use in clinical trials.
When the vaccine is to be trialled for human administration via a particular device, the same device should be employed in animal studies wherever feasible. The potential toxic effects of the pharmaceutical drug candidate should be evaluated in the context of the target organs, their intended dose, route/duration/frequency of drug exposure, and its potential reversibility. The assessment of the toxicity of the vaccine formulation can either be done through dedicated stand-alone toxicity studies or in conjunction with the evaluation of safety and efficacy.
Animal study data for IND studies should contain information regarding the source, species, and the procedure of animal husbandry. One relevant animal species is sufficient for use in tox studies for supporting the start of clinical trials.
Toxicological studies should be accomplished through a dose which aids in maximizing the animal exposure to candidate vaccine and the induced immune responses. This is even inclusive of the peak antibody response. Here, you do not need any particular evaluation of the dose-response studies as an inevitable part of your lethal dose and toxicity assessment. If toxic effects are evaluated in safety assessment through a specific route of administration, the further toxicological analysis may facilitate in achieving a full product toxicity spectrum.
The toxicity studies should assist in the evaluation of the product for its local inflammatory reactions and potent effects caused to your draining lymph nodes, the systemic toxicity profiling, and on the immune system.
The local tolerance should be evaluated either as a part of the stand-alone study or the repeated dose toxicity. Tolerance is usually determined at the target sites of your vaccine antigens as well as those sites which are inadvertently exposed to the vaccine antigens.
In certain conditions, evaluations arising out of the immune response from both the clinical and non-clinical studies or from the natural disease data highlights the immunological assessment of toxicity. Common examples of such immunological assessment of toxicities are immune complex precipitation and cell-mediated or humoral cell responses.
It is not necessary to undergo developmental toxicity studies for vaccines that are intended for child immunization process. However, if your target population is inclusive of pregnant women or lactating mothers, it is inevitable to conduct such developmental studies, unless and until the drug manufacturer puts forth a scientifically and clinically sound argument that these studies are irrelevant.
There is no need for genotoxicity studies in the final vaccine formulation stage. However, they are deemed necessary for particular components of vaccine such as additives and novel adjuvants. Adjuvants may be used as a part of the vaccine formulations or may be co-administered along with vaccines for enhancing the immune response produced against a particular antigen.
