Purpose: A single-center phase II study was performed to evaluate the efficacy of recombinant interleukin-2 (rIL-2) administered by continuous infusion to patients with metastatic renal cell carcinoma (RCC).
Patients and methods: Thirty-one patients with RCC were entered onto the study. rIL-2 (Proleukin; Eurocetus Corp, Amsterdam, The Netherlands) was administered intravenously in a dose of 18 x 10(6) IU/m2 per 24 hours. A maximum of two induction cycles and four maintenance cycles were given. Each induction cycle consisted of two rIL-2 infusion periods of 120 hours and 108 hours duration, respectively; these were separated by a 6-day rest period. Each maintenance cycle consisted of a 120 hours rIL-2 infusion period.
Results: Six of 30 assessable patients (20%) responded; two (7%) with a complete response (CR) and four (13%) with a partial response (PR). The response duration for patients with CR was 209 and 715+ days, and for those with PR 161, 197, 245, and 353 days. Seven patients had stable disease (SD) with a median duration of 261 days (range, 127 to 381 days). The overall median survival was 261 days (range, 13 to 905+ days). The most frequent toxicities requiring dose reductions of rIL-2 were: hypotension in 87% of patients, dyspnea in 32%, CNS toxicity in 55%, and an increase in serum creatinine levels in 48%. Septicemia occurred in 16% of patients. Toxicities usually reversed on interruption of rIL-2 infusion. One patient (3%) died as a result of the treatment from initial CNS toxicity followed by multiorgan failure.
Conclusions: The study confirmed the antitumor efficacy of rIL-2 administered by continuous infusion in patients with metastatic RCC. The response rate was similar to that obtained by high-dose bolus injections of rIL-2. Toxicity was substantial but manageable in a specialized oncology ward without routine use of an intensive care unit.