Background: The standard dosing schedule for administration of Sunitinib is 50mg once daily for a 4-week period followed by 2 weeks off. However, in clinical practice, many patients require schedule or dose reductions to mitigate toxicity. We aimed to assess if these treatment modifications result in improved outcomes in mRCC patients. Methods: Data were drawn from STAR-TOR, a German, multi-centre, real-world, prospective registry to report outcomes of mRCC patients who received Sunitinib in 1L. Patients were categorised into 2 treatment groups: 1) Sunitinib initiated at standard schedule/dose with subsequent schedule/dose modification (SM), 2) Sunitinib as per standard schedule/dosage (SS). Kaplan-Meier survival analysis was used to determine time on treatment (TT) of Sunitinib and progression-free survival (PFS). Differences between groups were assessed using log-rank tests. Results: In total 297 patients were identified initiating 1L Sunitinib. Schedule or dose reductions occurred in 33% of patients. Significant differences between groups at baseline are noted in Table 1. Median TT was greater in SM vs. SS (15.1 vs. 3.9 months (m), p < 0.0001). Median PFS was improved in SM vs. SS (15.1 vs. 6.0 m, p < 0.0001). Fatigue (31/14%), hand-foot syndrome (HFS) (28/10%), diarrhea (35/19%) and stomatitis (20/6%) were more frequently reported in SM vs. SS since initiation of Sunitinib. Incidence of adverse events, (excluding diarrhea) was reduced following schedule/ dose modification of sunitinib; fatigue (before SM/ after SM) (18/7%), HFS (21/8%) and stomatitis (8/4%). Conclusions: Modifying Sunitinib schedule or individualizing the dose represent therapy management strategies that are associated with improved tolerability, prolonged treatment duration and significant improvement in PFS in a real life setting. These data suggest that effective management of toxicity of Sunitinib can optimize patient outcomes.

Vs SS: *p < 0.05; **p < 0.0001