Multiple -dose toxicity studies

Single and repeat dose toxicity studies (with later mainly in the rat and dog by oral or intravenous route and up to 1 year duration), reproduction toxicity (embryo-foetal studies in the rat and rabbit), battery of genotoxicity assays, carcinogenicity studies (by diet route in mouse and rat) plus ADME studies (single and multiple dosing)... 

Products that may have the potential to stimulate growth or induce proliferation or clonal expansion of cell types, in particular, transformed cells, all processes that may eventually lead to neoplasia should be evaluated with respect to receptor expression in various malignant and normal human cells that are relevant to the patient population under study [27], In such cases normal human cell lines and multiple human cancer cell lines expressing the relevant receptor, as well as primary cells derived from human tumor explants, should be used for in vitro assessment. When in vitro data demonstrate enhanced growth, further studies in relevant in vivo xenograft animal models with receptor expressing tumor cell lines may be needed. In addition incorporation of sensitive indexes of cellular proliferation in long-term repeat-dose toxicity studies may provide useful information. 

Multiple time points are included in study designs to assess acute and late effects as well as the reversibility of any adverse effects. The route of administration should reflect the intended clinical use. Repeated-dose toxicity studies are only relevant if the clinical use includes multiple dosing. For example, in the case of p pancreatic islet cells, toxicity studies should mimic the clinical scenario of retransplantation assessment of acute toxicities and cumulative effects that would preclude retransplantation. 

Pivotal safety studies in a single relevant species are usually appropriate for MAbs, as are single-dose pharmacokinetic studies, a multiple-dose toxicity assessment with toxico-kinetic sampling, and immunogenicity studies. 

Traditionally, the duration of a toxicity study depends on the intended clinical use and disease duration. The potential immunogenicity of the human protein is a significant issue since antibody binding can partially or completely inhibit the biological activity of that protein, affect its catabolism or alter its distribution and clearance. Any multiple-dose study therefore should include evaluation of the impact of antibody formation, including their neutralizing capacity. However, antibody formation in itself should not be a reason for termination of a toxicity study, particularly if the antibodies are not neutralizing or do not alter the pharmacodynamics of the protein. 

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