Interleukin-12: potential role in cancer therapy.

IL-12 is a heterodimeric cytokine that promotes cell-mediated immunity through its regulatory effects on T and NK cells. IL-12 produced endogenously in response to various microbial agents likely plays a role in the host response to infection by intracellular pathogens, and administration of rIL-12 to mice has bee shown to have dramatic therapeutic effects in a number of tumor models and models of infectious diseases. The relatively long serum half-life of IL-12 compared to other lower molecular weight cytokines such as IL-2 should permit more flexibility in dose scheduling. At doses which are efficacious in murine tumor models, IL-12 has been well tolerated. Phase I clinical trials with IL-12 in the treatment of human malignancies have recently been initiated. The results of such studies are required to determine whether the therapeutic potential IL-12 has displayed in murine disease models can be translated into clinical utility in man.