Purpose: Metastatic renal cancer patients with a single metastatic site are potentially amenable to interleukin 2 (IL-2) + IFN-alpha. A French immunotherapy intergroup multicenter trial assessed the potential benefit of i.v. over s.c. administration of IL-2 in this combination.
Experimental design: Untreated patients with one metastatic site were randomized to continuous i.v. infusion (18 x 10(6) IU/m(2)/d; arm A) or twice daily s.c. injections (9 x 10(6) or 18 x 10(6) IU; arm B) of IL-2, associated with s.c. IFN-alpha (6 x 10(6) IU) 3 days per week in both arms. Tumor response was assessed (WHO criteria) at weeks 12 and 24 to 26. The primary end point was overall survival, with an expected 15% improvement at 4 years with i.v. IL-2. The planned sample size was 220 (80% power, 5% significance, one-sided test). Intent-to-treat analysis was done and survivals were compared using log-rank tests.
Results: From January 2000 to January 2005, 80 and 75 patients were randomized to arms A and B, respectively. Enrollment was stopped early because of low accrual; analysis was done at 42.5 months median follow-up. Patient characteristics were well balanced between groups. Response rates were 17.9% versus 21.3% in arms A and B. Progression-free survival rates were not significantly different. Overall survival difference was not significant: median 33 months (95% confidence interval, 27.0-40.2; P = 0.202).
Conclusions: In combination with IFN-alpha in selected, good prognosis metastatic renal cell carcinoma patients, i.v. IL-2 offers no significant advantage over s.c. IL-2 and induces higher toxicity. Although i.v. IL-2 induced longer responses, it seems unreasonable to continue recommending this regimen after the recent introduction of more effective therapies.