INTERLEUKINS IN CANCER-THERAPY - RATIONALE AND CURRENT STATUS

The interleukins function as intercellular hormones, and have the capa city to alter the activity of a target cell population. Immunotherapy with interleukin-2 (IL-2) constitutes a new treatment strategy for mal ignancies otherwise not responsive to traditional cytotoxic chemothera py. In advanced renal cell carcinoma, studies using high dose bolus IL -2 alone have resulted in mean objective response rates of approximate ly 15% (0 to 27%). Durable responses in some patients have translated into increased survival. With advanced melanoma, high dose bolus IL-2 therapy alone produces response rates ranging from 21 to 24%, although other studies using lower doses, different drug preparations or diffe rent schedules have resulted in lower response rates. Studies are now under way using IL-2 in combination with interferons, cytotoxic chemot herapy, monoclonal antibodies and tumour infiltrating lymphocytes in a n attempt to enhance the biological activity of IL-2. Another promisin g use of IL-2 therapy is in the treatment of acute leukaemia. Several small studies have shown benefit of IL-2 given to patients in early re lapse, leading to normalisation of bone marrow and prolonged remission s in some patients. IL-2 is currently being investigated as a post-tra nsplant adjuvant strategy in patients undergoing bone marrow transplan tation for haematological malignancies. Newly characterised interleuki ns such as IL-4 and IL-6 have demonstrated preclinical antitumour and immunoenhancing properties, resulting in their recent introduction int o clinical trials. Additionally, IL-6 has demonstrated thrombopoietic enhancing activity in early clinical trials and has a potential applic ation in ameliorating thrombocytopenia associated with myeloablative c hemotherapy. In summary, these interleukins have proven to be effectiv e additions to treatment strategies in oncology.