THE PRESENT SITUATION OF IMMUNOTOXICITY STUDY IN DEVELOPMENT OF DRUGS

Immunotoxicity study is not required for development of a new drug in GLP guidelines in Japan. However, the need of such a study is growing with the progress of development of biotechnology products, antiviral agents against AIDS, immunotherapeutics, etc. According to the result of the questionnaire undertaken by JPMA, 18 out of 78 pharmaceutical companies have conducted immunotoxicity study on case-by-case basis. The main reasons why the study was conducted were based on the results of general toxicity studies, the pharmacological effects, and/or the trend of related-compounds, such as anti-cancer drugs. The findings judged to be associated with immunotoxicity consisted of histopathological changes in lymphoid tissues, weight changes in lymphoid organs and changes in bone marrow assay, hematology test, and blood chemistry test. Immunotoxicity of drugs were examined for cell-mediated immunity, humoral immunity, non-specific immunity, host resistance, and lymphocyte surface antigens. This survey showed that some companies have already established the testing capabilities for immunotoxicity study, but setting up a guideline for immunotoxicity study should be done with circumspection because determining immunotoxic effects is complicated.