The impact of interleukin-2 on survival in renal cancer: a multivariate analysis

The purpose of this analysis was to compare the survival of patients with advanced renal carcinoma treated with intravenous recombinant interleukin-2 to the survival of matched patients taken from the large and well characterised database of the Eastern Cooperative Oncology Group (ECOG). Recombinant interleukin-2 (rIL-2) given by continuous intravenous infusion was used to treat 387 patients with advanced adenocarcinoma of the kidney in five multi-centre studies and 327 of these patients fulfilled the study eligibility criteria and were evaluable for response, toxicity and survival. The survival of patients treated with rIL-2 was compared in a multi-variate survival analysis taking account of all identified prognostic factors to 390 control patients receiving chemotherapy derived from the database. Thirteen patients treated with rIL-2 achieved a complete remission of their disease and 32 a partial remission giving an overall response rate of 14%. Remissions were durable with a median duration of 357 days for partial remissions and a median duration in excess of 926 days for complete remissions. Most patients experienced fever or mild to moderate hypotension and other toxicities are described. However, only 11 patients required admission to intensive care and in only five cases was this judged to be due to treatment toxicity. There were three deaths judged to be probably due to treatment toxicity. rIL-2 treatment was associated with significantly prolonged survival compared to the ECOG control patients. Patients with good prognostic features appeared to have a greater survival benefit from rIL-2 than those with poor prognostic features. This analysis provides the first evidence that rIL-2 prolongs survival in patients with advanced renal cancer but cannot provide proof which should be sought in randomised prospective trials drawing on the hypotheses generated herein.