A Randomized Study of Low-Dose Interleukin-2 Subcutaneous Immunotherapy versus Interleukin-2 plus Interferon-Alpha as First Line Therapy for Metastatic Renal Cell Carcinoma

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Abstract
Aims and Background: IL-2 given subcutaneously in combination with interferon-alpha 2b (IFN) appears to induce a response rate comparable to that obtained with IL-2 intravenous injection in patients with metastatic renal cell carcinoma (RCC) but with lower toxicity. The role of IFN when combined with IL-2 has however still to be defined. The present study was performed to draw some preliminary conclusions about the effect of IFN in combination with IL-2 in metastatic RCC. Methods: The study included 30 consecutive patients with metastatic RCC who were randomized to treatment with IL-2 subcutaneous therapy (3 million IU twice/daily for 5 days/week for 6 weeks) or with IL-2 plus IFN (5 million U/m2 subcutaneously thrice weekly). In patients without progressive disease, a second cycle was repeated after a 28-day rest period. Results: No significant difference in partial response rate was found between patients treated with IL-2 alone and those given IL-2 plus IFN (5/15 vs 4/15). Similarly, no difference was seen in the percentage of stable disease (7/15 vs 7/15). Toxicity was higher in patients who received IL-2 plus IFN. Lymphocyte and eosinophil mean increase was higher in patients treated with IL-2 alone than in those treated with IL-2 plus IFN, without however any significant difference. Conclusions: The present results, which require confirmation in a larger series, indicate that combination with IFN does not increase the efficacy of IL-2 subcutaneous immunotherapy in metastatic RCC but only the toxicity of treatment.