Purpose: This prospective, randomized, controlled phase III trial assessed high-dose bolus interleukin-2 (IL-2) postoperatively in patients with high-risk renal cell carcinoma (RCC).
Patients and methods: Eligibility requirements were resected locally advanced (LA; T3b-4 or N1-3) or metastatic (M1) RCC, no prior systemic therapy, and excellent organ function. Randomized assignment was to one course of IL-2 (600,000 U/kg every 8 hours on days 1 to 5 and days 15 to 19 [maximum 28 doses]) or observation. The study was designed and powered to show an improvement in predicted 2-year disease-free survival (DFS) from 40% for the observation group to 70% for the treatment group. The accrual goal was 68 patients with LA disease, with 34 patients per treatment arm. Metastasectomy patients were to be analyzed separately because of their unpredictable natural history.
Results: Sixty-nine patients were enrolled onto the study (44 LA and 25 M1 patients). Toxic effects of IL-2 were as anticipated; no unexpected serious adverse events or treatment-related deaths occurred. Early closure occurred when an interim analysis determined that the 30% improvement in 2-year DFS could not be achieved despite full accrual. Sixteen of 21 LA patients receiving IL-2 experienced relapse, compared with 15 of 23 patients in the observation arm (P =.73); in the LA group, three deaths occurred in the IL-2 arm, and five deaths occurred in the observation arm (P =.38). Analysis including metastasectomy patients made no difference in DFS or overall survival.
Conclusion: One course of high-dose bolus IL-2, though feasible, did not produce the ambitious clinically meaningful benefit anticipated when administered postoperatively to patients with resected high-risk RCC.