- BACKGROUND: Sunitinib is administered on a rigid schedule that may not be optimal for all patients. We hypothesised that toxicity-driven dose and schedule changes would optimise drug exposure and outcome for each patient. MATERIALS AND METHODS: In a phase 2 trial, 117 patients with metastatic clear cell renal cell cancer were started on sunitinib 50 mg/day with the aim to treat for 28 days. Treatment breaks were reduced to 7 days. Sunitinib dose and the number of days on therapy were individualised based on toxicity aiming for ≤ grade II toxicity with dose escalation in patients with minimal toxicity. The null hypothesis for the primary end-point was a progression-free survival (PFS) of 8.5 months based on a study with similar eligibility criteria. RESULTS: The null hypothesis was rejected (p < 0.001) with a median PFS of 12.5 months (95% confidence interval [CI]: 9.6-16.5). The median overall survival was 38.5 months (95% CI: 28.3-not reached). The objective response rate (46.1%) and stable disease rate (38.5%) translated into a clinical benefit for 84.6% of patients with no decline in quality of life scores during therapy. Fewer patients were dose reduced (26.5% vs. 50%) or discontinued due to toxicity (7.7 vs. 18-20%) compared to standard sunitinib dosing, and 20 (18.4%) patients were dose escalated to 62.5 mg (12) and 75 mg (8) with a wide individual variation in the optimal dose and treatment duration. CONCLUSIONS: Individualised sunitinib therapy is feasible, safe and an effective method to manage toxicity with one of the best efficacy seen for oral vascular endothelial growth factor inhibitors in metastatic renal cell carcinoma. CLINICALTRIALS. GOV IDENTIFIER: NCT01499121.