Clinical outcome of high-dose bolus intravenous interleukin-2 with a modified administration schedule for Asian patients with metastatic renal cell carcinoma.

Purpose: The standard regimen of high-dose interleukin-2 (HDIL-2) for metastatic renal cell carcinoma (RCC) is two cycles separated by 9 days, which constitutes one course. Each course is separated by an 8-12 weeks. However, the 9-day interval between each HDIL-2 cycle is often not long enough to allow recovery from adverse effects. Therefore, we modified HDIL-2 schedules by increasing the interval between each cycle without changing the total cumulative doses of IL-2.

Methods: Clinical data from 37 patients who were treated with modified HDIL-2 schedule were reviewed. Patients received the first dose of IL-2 on day 1 and took subsequent doses every 8 h for a maximum of 14 doses each cycle. Treatment was repeated every 4 weeks, and a maximum of six cycles were planned.

Results: The overall response rate was 35% including two patients with complete response. With a median follow-up duration of 46.9 months, median progression-free survival was 16.0 months (95% CI 10.2-21.7 months) and median overall survival was 58.9 months (95% CI 49.6-68.3 months) with a 3-year overall survival rate of 77.8%. Toxicity profile was acceptable and comparable to standard HDIL-2 schedule. There were no treatment-related mortalities. The incidence of ≥grade 3 adverse events did not differ between patients who had prior exposure to vascular endothelial growth factor receptor tyrosine kinase inhibitor (VEGFR TKI) and VEGFR TKI-naïve patients.

Conclusion: Modified HDIL-2 schedule seems to be a safe and effective option for selected Asian patients with metastatic RCC, even in patients with prior VEGFR TKI treatment.