From January 1987 to February 1988, 15 stage IV melanoma patients were treated with two courses of bolus injection of rIL-2 plus LAK cell infusions at the National Cancer Institute of Milan. The original treatment regimen included a first course of rIL-2 administration (400 micrograms/m2 bolus injection 3 times a day [TID] for 4 days) and a second course of rIL-2 administration (800 micrograms/m2 bolus injection TID for 7 days) separated by 4 consecutive daily leukaphereses. Autologous lymphokine activated killer (LAK) cells were reinfused into each patient on three occasions during the second period of rIL-2 administration. Due to the appearance of grade III-IV neurological, hepatic and cardiopulmonary toxicity, 7 patients discontinued dosing before the end of treatment, one patient desired to be withdrawn and one patient died from rapidly progressive disease, although complications of rIL-2 administration may have contributed to her death. Only 6 patients completed the schedule without evidence of major intolerance, even though the planned dose during the second course of rIL-2 was reduced to 400 micrograms/m2. The complete duration of treatment ranged from 11 to 19 days. The total dose of rIL-2 injected ranged from 12.6 to 30.4 mg. The number of infused LAK cells ranged from 15.5 x 10(9) to 60 x 10(9)/patient. Two of the 14 evaluable patients showed a minor anti-tumor response. In 5 patients new metastases in other sites were documented from 2 to 5 months after completion of dosing. No apparent association was found between progression of the disease (or the appearance of new metastases) and the total dose of rIL-2 injected, the number of LAK cells administered or the number of days of treatment. By December 1988, all patients had died of their disease in a period ranging from 3 to 14 months from the last injection of rIL-2. The lack of significant clinical responses in this study and the high toxicity of this treatment lead us to conclude that at least as far as melanoma patients are concerned, adoptive immunotherapy with rIL-2 plus LAK cells (as described here) is not a justifiable treatment option unless new evidence presents itself.