Antitumor antibiotics discovered and studied at the Institute of Microbial Chemistry.

In 1951, we were pioneers in initiating screening of antitumor agents from microbial metabolites. We discovered bleomycin in 1962 and aclacinomycin in 1975. Peplomycin, a derivative of bleomycin, and pirarubicin, a tetrahydropyranyl derivative of doxorubicin, were also studied. All of them have been clinically used for the treatment of cancer. Using new screening methods, we isolated spergualin in 1982. This agent exhibited immunosuppressive activity as well as antitumor activity. Deoxyspergualin, a derivative of spergualin, is now clinically used for the treatment of acute rejection after kidney transplantation. Bestatin was screened as an inhibitor of aminopeptidase B in 1976. It binds to the aminopeptidases located on the cell membrane of immunocompetent cells and modulates immune responses. It is now used for the treatment of acute non-lymphocytic leukemia. Microbial metabolites will become more important as a source of anticancer drugs in the future.