[Possibilities and limits of the use of interferons in the clinic].

Only the recent production of large amounts of highly purified recombinant interferons has made it possible to elucidate precisely the in vitro and in vivo effect of alpha- and gamma-interferon. Interferon-alpha has significantly widened the treatment modalities for some rare tumors such as hairy cell leukemia and chronic myelogenous leukemia. Although treatment results in solid tumors are disappointing, tumor regression greater than 50% is achieved in 15-25% of patients with hypernephroma or melanoma, cancers highly resistant to cytotoxic drugs. The solid tumors must be treated with high doses of interferon-alpha which causes severe side effects. Interferon-induced toxicity can be reduced by continuous subcutaneous infusion. Interferon-alpha is also used for the treatment of viral diseases such as chronic hepatitis-B, as well as for patients with AIDS and Kaposi sarcoma. Other virus infections such as herpes simplex and condylomata acuminata represent the few established indications for treatment with interferon-beta. Interferon-gamma has distinct immunomodulatory effects in vitro and in vivo, although the clinical significance of this potential has not yet been established. Thus far the treatment results in tumor patients have been poor. The future will show if the combination of interferons with other biological response modifiers, such as tumor necrosis factor or interleukin-2, or with cytotoxic drugs, brings further progress in cancer treatment.