Biological response modifiers: Preclinical evaluation and clinical activity

Abstract

Biological response modifiers are agents capable of affecting the host immune response toward tumors and include those biological substances produced by the human mammalian cell genome. Interferons and other lymphokines, tumor antigens, antibodies and agents which can activate or stimulate host immune responses are all included in this general category of agents. With the advent of genetic engineering and with monoclonal antibody technology, highly pure preparations of these biological substances can now be produced for tests of activity in preclinical models and in man. As the initial results accrue with highly purified preparations of interferon and with monoclonal antibodies alone or conjugated to toxic substances, the possibility of tumor specific therapy is becoming a reality. The development of preclinical models to predict for clinical activity remains a most important task to attempt to bring to clinical trials the substances most likely to be efficacious as anticancer agents. Early clinical results indicate that many of these agents can give responses in patients with clinically perceptible disease and Phase II activity studies are just beginning to define the range of clinical activity for a variety of biological response modifying agents. The development of biological response modifiers through preclinical testing and into clinical trials will be discussed in detail.