A multicenter, phase II trial of continuous-infusion interleukin 2 (IL-2) was done in the Southwest Oncology Group to evaluate the efficacy and safety of this treatment in a broad-based population of patients with metastatic renal-cell carcinoma. Forty-seven patients from 11 different institutions were entered in this study, with 43 eligible. Two technically ineligible patients who received treatment and for whom records are available are included in the data analysis. Thus, there are 45 analyzable patients. Of these patients, performance status was 0 in 58% and 1 in 42%. Thirty-one patients had a prior nephrectomy, and 12 patients had received prior therapy. IL-2 was initially given at a dose of 4.5 x 106 Roche U/m2/day, 4 days a week, for 4 weeks in a row, followed by a 3-week rest period. Because of the difficulty in obtaining reimbursement for the hospitalization required on the days of IL-2 administration, after 10 patients had been entered, the treatment regimen was changed to 6 x 106 Roche U/m2/day for 4 days as an inpatient, followed by 2 weeks of potential outpatient treatment at a dose of 3 x 106 Roche U/m2/day for 4 days each week. This was followed by a 2-week rest period. Within the 45 analyzable patients, there were 0 complete responses and 6 partial responses, for a response rate of 13% (95% confidence interval 5.1-27%). Responses occurred in lung metastases, nodal disease, and in one patient with bone metastases and the primary kidney tumor. Response durations were 1 month, 1 month, 14 + months, 19 months, 26+ months, and 27 months. Of 12 patients with a nephrectomy and only lung metastases, 4 showed partial responses. Medial survival for all analyzable patients is 15 months (95% confidence interval 8-20 months). Toxicity was significant, with nausea and vomiting, diarrhea, fever and chills, dermatologic changes, and fatigue the most frequent. There were 18 instances of grade 4 toxicity, with the most common grade 4 toxicity, respiratory, found in 8 patients. There were two early deaths of probable heart-related causes while receiving treatment. A continuous-infusion IL-2 regimen that allows some potential outpatient treatment shows effectiveness and toxicity similar to that in other multicenter IL-2 infusion trials and high-dose intravenous bolus regimens.
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