Background: Biologic response modifiers have activity in renal cell carcinoma. The combination of interleukin-2 (IL-2) and beta-interferon (B-IFN) is synergistic in vitro. This trial was initiated to determine the efficacy of IL-2 alone and with B-IFN in advanced RCC.
Methods: Ambulatory patients with advanced RCC were randomly allocated to either IL-2 6 x 10(6) units/M2 intravenously (IV) three days a week for four weeks or IL-2 5 x 10(6) units/M2 IV plus B-IFN 6 x 10(6) units/M2 IV three days a week for 4 weeks. This induction phase was followed by a maintenance phase of the same drugs and doses administered for two weeks out of every four.
Results: 84 patients were entered onto this phase II trial with 75 considered eligible for response and survival. Toxicity is reported for the 81 patients on whom data was received, irrespective of eligibility. The overall response rate (RR) was 9.3% (7/75). Of the 3 responses in the IL-2 arm (RR = 8.3%), one was a complete response. 4 patients in the IL-2 + B-IFN arm (RR = 10.3%) achieved a partial response. Median survival was estimated to be 8.4 months for patients given IL-2 and 8.0 months for patients given the IL-2 and B-IFN combination. Multivariate analysis of survival data identified initial performance status, metastases of > 1 site, and weight loss as being important prognostic factors for survival. There were 2 lethal and 3 life threatening toxicities with the IL-2 treatment. While there were no lethal toxicities on the combination arm, there were 4 life threatening toxicities.
Conclusions: The results of this study indicate that further investigation of IL-2 with or without B-IFN at this dose and schedule as treatments for renal cell carcinoma is probably not warranted.