Subcutaneous recombinant interleukin-2 (rIL-2) in out-patients with metastatic renal cell carcinoma. Results of a multicenter SCAPP1 trial.

Background: This multicenter phase II trial was conducted in order to evaluate the efficacy and toxicity of the subcutaneous route of administration of rIL-2 in the treatment of patients with metastatic renal cell carcinoma and to check whether an increased cumulative dose of rIL-2 increases efficacy.
Patients and Methods: Thirty-nine patients with metastatic renal cell carcinoma were included in this study. During the induction period, rIL-2 was administered subcutaneously 5 days a week for 8 weeks. The weekly dosages were 90 MIU during weeks 1 and 6;63 MIU during weeks 2 to 4 and 7 to 9. After evaluation, responders and patients with stable disease received maintenance treatment which was discontinued upon the appearance of disease progression or unacceptable toxicity. During the maintenance period, rIL-2 was administered 5 days a week for 4 weeks followed by a 2-week rest period. The weekly dosages were 90 MIU in week 1 and 63 MIU in weeks 2 to 4.
Results: After completion of induction treatment, 7 of 39 evaluable patients (18%) had objective responses (95% CI: 9% to 37%) with one complete response. Treatment was interrupted or reduced due to toxicity for seven patients: Neuropsychiatric symptoms (3 patients), joint pain (1 patient), major asthenia and anorexia (1 patient), stroke (1 patient), and septicemia (1 patient). Other systemic side effects in the remaining patients were acceptable. Seventeen patients received maintenance treatment. In none of the patients did the response status improve during this maintenance period. The median follow-up of all of the patients included was 19 months. The one- and two-year survivals were 65% and 33%, respectively, ad the median duration of response was 11 months (5 to 16+).
Conclusions: This multicentric study confirms the efficacy of subcutaneously-administered rIL-2 in patients with metastatic renal cell carcinoma in terms of both response rate and survival. The role of a maintenance therapy needs further evaluation.