OBJECTIVE To confirm the antitumor efficacy of treatment with interleukin-2 and lymphokine-activated killer cells in patients with metastatic renal cancer. METHODS Nonrandomized, phase II clinical trial. METHODS Tertiary care units in university medical centers. METHODS Consecutive trial of 35 patients with metastatic or unresectable renal cell cancer who have bidimensionally measurable disease, performance status 0 or 1, and normal function of all vital organs. Thirty-two patients completed interleukin-2 priming and received at least one lymphokine-activated killer cell infusion. Three patients were removed from the study and did not receive infusion of cells secondary to rapid tumor progression or toxicity. METHODS Patients initially received recombinant interleukin-2, 100,000 units/kg body weight every 8 hours, on days 1 to 5 in a priming phase to stimulate lymphokine-activated killer cell precursors and effector activity in vivo. Leukapheresis was done on days 8 to 12 and lymphocytes were cultured in vitro with interleukin-2 for 3 to 4 days to amplify lymphokine-activated killer cell activity. Finally, interleukin-2, 100,000 units/kg every 8 hours, was infused with cultured cells on days 12 to 16. All doses of interleukin-2 and lymphokine-activated killer cells were administered in intensive care units. RESULTS The mean number of doses of interleukin-2 administered during the priming phase was 12.9 +/- 0.4; the mean number of lymphokine-activated killer cells reinfused was 7.0 +/- 0.6 X 10(10); and the mean number of interleukin-2 doses administered during the last phase was 10.2 +/- 0.6. The overall objective response rate was 16%; two patients had complete responses and three patients had partial responses with greater than 50% reduction of all measurable tumor. The complete responders remain disease-free at 12 and 9 months. Two partial responders have not had tumor regrowth at 16 and 15 months. The third partial responder relapsed at 4 months. Toxicity was severe but generally of short duration and manageable. There were no treatment-related deaths. Hypotension, weight gain, anemia, and elevations of serum creatinine levels and liver enzymes were common. Two patients required intubation; one patient had a myocardial infarction. CONCLUSIONS This phase II study confirms the antitumor activity of interleukin-2 and lymphokine-activated killer cell therapy in patients with metastatic or unresectable renal cell cancer. Response rates, especially complete remission rates, are comparable or better than rates achieved with other forms of therapy.