[Interferons as antineoplastic drugs--direct regulatory effects on tumor cells].

Interferons (IFNs) are a family of pleiotropic cell regulatory molecules and members of the cytokine network. Apart from a central role in the body's first-line defence against infections, they are important in regulation of immune responses and may be involved in control of cell growth and differentiation. Over the past ten years, clinical trials provided unequivocal evidence that IFNs to have anticancer activity, even though this is valid in a restricted range of tumours mainly of haematopoietic origin. We currently suppose three ways in which IFNs could affect tumour growth: 1. Direct regulatory effects on tumour cells. 2. Immunomodulatory effects that enhance or even initiate a host response to the tumour. 3. Regulatory effects on host/tumour interaction not associated with immune responses. We reviewed the direct regulatory effects of IFNs on tumour cells and results of clinical trials of IFNs in cancer therapy. (Tab. 2, Ref. 85.)