OBJECTIVES : Sunitinib, a first-line (1L) treatment option for patients with metastatic renal cell carcinoma (mRCC), has a standard dosing schedule of 50mg once daily for a 4-week on 2 weeks off cycle (4:2). However, studies with small selected populations have reported improved outcomes with schedule alterations. We investigated the impact of different 1L sunitinib dosing schedules on treatment duration and survival in a real-world setting for a nationwide Swedish mRCC cohort.

METHODS : This was a retrospective analysis utilizing the population based Swedish Health Data Registers. The cohort included all mRCC patients aged ≥ 18 years with ≥ 1 filled prescription from July 2005–December 2019. Three dosing schedules were analyzed: starting on 4:2, starting on 2 weeks on 1 week off (2:1) and starting on 4:2 then switching to 2:1 (SW). A grace period of 90 days was permitted between filled prescriptions to allow for medication accumulated from overlapping prescriptions; patients exceeding this period were defined as non-persistent. Outcomes were time-to-treatment discontinuation (TTD) and overall survival (OS) as analyzed by Kaplan-Meier methods.

RESULTS : 1095 patients with mRCC were identified initiating 1L sunitinib (2:1, n=320: SW, n=71: 4:2, n=704) and baseline characteristics including, age, gender, and age at RCC-diagnosis were similar between subgroups. TTD (95% CI) was significantly different between subgroups (p<0.001) with median at 6.20 (5.6, 7.2), 13.91 (8.1, 20.6) and 4.55 (4.3, 5.6) months for 2:1, SW and 4:2 dosing, respectively. OS (95% CI) also differed significantly between subgroups (p<0.001) with median at 21.79 (18.1, 26.1), 32.20 (25.1, 48.3) and 13.48 (12.3, 15.8) months for 2:1, SW and 4:2 dosing, respectively.

CONCLUSIONS : Modified 1L sunitinib schedules were associated with prolonged treatment duration and OS. The greatest benefit was observed in patients who switched from 4:2 to 2:1; however, data from patients starting 2:1 dosing was comparatively immature.