Purpose: A phase II trial that used a regimen of interleukin-2 (IL-2) and interferon alfa-2a (IFN-alpha) was undertaken to evaluate the efficacy of this combination in the treatment of metastatic renal cell carcinoma.
Patients and methods: Thirty-four assessable patients were treated with one to two induction cycles of IL-2 administered by continuous intravenous (IV) infusion at a dose of 3 x 10(6) U/m2/d [corrected] for 4 days per week plus IFN-alpha administered by subcutaneous injection at a dose of 5 x 10(6) U/m2/d [corrected] for 4 days per week for 3 consecutive weeks. A maintenance regimen of IL-2 2 x 10(6) U/m2/d [corrected] given by continuous IV infusion for 5 days per week plus IFN-alpha subcutaneously at a dose of 6 x 10(6) U/m2/d [corrected] that was given 3 days per week for 3 weeks was administered for one to five cycles. Twenty-eight patients (82%) completed one to two induction cycles, and 14 patients (41%) received maintenance doses.
Results: Major responses were achieved in four patients (12%), which included one complete response (CR) in a bone metastasis. Responses were observed in patients both with and without prior nephrectomy as well as in a primary tumor. Toxicity was moderately severe and included two treatment-related deaths.
Conclusions: In view of the minimal antitumor activity and associated toxicity, the combination of IL-2 and IFN-alpha in this trial cannot be recommended. The investigation of new cytokines and the identification of biologic prognostic factors for a response to immunologic therapy are essential.