Real-world experience of the feasibility and tolerability of the 2/1 dosing schedule with sunitinib in the treatment of patients with advanced renal cell carcinoma in Australia

Aim: Sunitinib is a first-line treatment option for metastatic renal cell carcinoma (mRCC) funded by the Australian Pharmaceutical Benefits Scheme. Toxicities are common with the standard schedule leading to alternative dosing schedules to be suggested. We reviewed Australian treatment practices to evaluate the safety and outcomes of patients on a 2 weeks on, 1 week off treatment schedule (2/1). Methods: We performed a retrospective review of 63 patients with mRCC treated with first-line sunitinib on a 2/1 schedule at four Australian centers. Results: Forty-six patients (73%) initiated sunitinib on the 2/1 schedule whereas 17 (27%) switched from the 4/2 schedule due to toxicity. Three progressing on a 4/2 schedule tolerated up-titration of their dose with a clinical and radiological response on the 2/1 schedule. The median duration of treatment was 31.9 months; median duration of treatment on the 2/1 schedule in patients changing from 4/2 was 11.5 months. Few (6.3%) ceased due to toxicity. Median overall survival was 37.2 months. Conclusion: In this retrospective review of the 2/1 sunitinib schedule, time on treatment with clinical benefit exceeded the overall survival times seen in the phase III trials utilizing the 4/2 schedule. Overall survival also exceeded that seen in these trials. Few patients ceased due to toxicity. The 2/1 schedule appears to be an acceptable schedule to use in selected patients with mRCC both at initiation of first-line treatment and in those intolerant to the 4/2 schedule.