Alternative prescription schedules of sunitinib in metastatic kidney cancer: from the underground to the light?

Background. Sunitinib was the first targeted therapy improving progression-free survival (PFS) and overall survival (OS) in patients with metastatic renal cell carcinoma (mRCC) in the first line of treatment. Classically, sunitinib is administered at a dose of 50 mg/day during four weeks followed by two weeks off (schedule 4/6). This schedule has two pitfalls: intermittent exposure with two weeks ``off'' and the increase in toxicity during the fourth week. Several alternative prescription schedules were studied with the aim of limiting the intensity of toxicity while maintaining efficacy. This review summarizes the published data on alternative schedules of sunitinib in terms of safety and efficacy. Methods. All articles and abstracts on alternative schedule of sunitinib in the mRCC were reviewed. Clinical trials were also searched. Results. Studies evaluating the continuous schedule have not provided evidence of its superiority compared to the 4/6 schedules in terms of activity, tolerance or dose-intensity. Retrospective data of patients treated in a schedule two weeks of treatment ``on'' ``off'' (schedule 2/3) with sunitinib 50 mg/day show PFS that seem superior to those obtained with a schedule 4/6, while having a better safety profile. Conclusion. The alternating schedule of sunitinib 2/3 (50 mg/day) may be a better alternative to schedule 4/6 in terms of tolerance. If toxicity occurs with 50 mg/day on a schedule 4/6, it would probably offer a better alternative in terms of efficiency than dose reduction. The results of ongoing and future studies are expected to prospectively validate the concept.