On January 26, 2006, sunitinib (Sutent) received regular approval as monotherapy for the treatment of patients with gastrointestinal stromal tumor after disease progression on or intolerance to imatinib mesylate (Gleevec). Time-to-tumor progression (TTP) of sunitinib-treated patients was superior to that of placebo-treated patients. Median TTP of sunitinib-treated patients was 27.3 weeks, compared with 6.4 weeks for placebo-treated patients (p < .0001). Partial responses were observed in 6.8% of sunitinib-treated patients and no placebo-treated patients. Sunitinib also received accelerated approval on January 26, 2006, as monotherapy for treatment of advanced renal cell carcinoma (RCC). In two single-arm trials of sunitinib in patients with metastatic RCC, partial responses were observed in 25.5% (95% confidence interval [CI], 17.5, 34.9) and 36.5% (95% CI, 24.7, 49.6) of patients. Median response durations in the two trials were 27.1 weeks (95% CI, 24.4, incalculable) and 54 weeks (95% CI, 34.3, 70.1). Treatment-emergent adverse events in sunitinib-treated patients included diarrhea, mucositis, skin abnormalities, altered taste, electrolyte abnormalities, hypertension, and diminution in left ventricular ejection fraction. Cardiac safety of sunitinib in patients with preexisting cardiac abnormalities remains unknown. Based on nonclinical findings, physicians prescribing sunitinib should monitor for adrenal insufficiency in patients who undergo stressors such as surgery, trauma, or severe infection. Caution should be exercised when administering sunitinib in combination with known CYP3A4 inducers or inhibitors.