Cytokine therapy for hematological malignancies.

Recently various cytokines have been introduced into the clinic and have played important therapeutic roles in the treatment of hematological malignancies. Among these cytokines, I have focused on interferon (IFN) and granulocyte (G) or granulocyte-macrophage (GM) colony stimulating factor (CSF), which are currently the most useful cytokines, in this review. IFN-alpha has been approved for chronic myelogenous leukemia (CML), multiple myeloma and hairy cell leukemia. In addition, IFN-alpha has therapeutic potentials for low grade non-Hodgkin's lymphoma, cutaneous T cell lymphoma and adult T cell leukemia/lymphoma. Thus, IFN-alpha is one of the most useful and wide-ranging antitumor agents in hematological malignancies. Most striking effects have been studied in chronic phase CML. Cytogenetic responses are seen in 30-40% of the treated patients and a complete cytogenetic response can be seen in about 10%. Long-term survival can be expected in these patients. Considering the risk of graft-versus-host disease-associated mortality in allogeneic bone marrow transplantation, the category of treatment is difficult to choose in IFN-responsive patients. Elucidation of the antitumor mechanism of IFN, as a prototype for other biological response modifiers, may revolutionize cancer treatment. G- and GM-CSF (CSFs) have reduced the duration of neutropenia, incidence of infectious episodes and days of hospitalization following cancer chemotherapy or stem cell transplantation. CSFs have also been used to mobilize peripheral blood stem cells and to increase dose intensity of chemotherapeutic agents. Leukemic cells from many patients with acute myelogenous leukemia (AML) have surface receptors for CSFs and may proliferate in response to CSFs. However, several randomized studies showed that CSFs can be used safely and effectively in augmenting neutrophil recovery in patients with AML when given after induction chemotherapy. Various trials have been made to prime leukemic cells by CSFs to make them more susceptible to chemotherapy, but no convincing evidence has been obtained.