Sunitinib (marketed as Sutent by Pfizer, and previously known as SU11248) is an oral, small-molecule, multi-targeted receptor tyrosine kinase inhibitor that was approved by the FDA for the treatment of renal cell carcinoma (RCC) and imatinib-resistant gastrointestinal stromal tumor. Sunitinib was evaluated for its inhibitory activity against a variety of kinases and was identified as an inhibitor of platelet-derived growth factor receptors (PDGFRa and PDGFRb), vascular endothelial growth factor receptors (VEGFR1, VEGFR2, and VEGFR3), stem cell factor receptor (KIT), Fms-like tyrosine kinase-3 (FLT3), colony-stimulating factor receptor Type 1 (CSF-1R), and the glial cell-line derived neurotrophic factor receptor (RET). Sunitinib adverse events are considered somewhat manageable and the incidence of serious adverse events low. The most common adverse events associated with sunitinib therapy are fatigue, diarrhea, nausea, anorexia, hypertension, yellow skin discoloration, hand-foot skin reaction, and stomatitis. In the placebo-controlled Phase III GIST study, adverse events which occurred more often with sunitinib than placebo included diarrhea, anorexia, skin discoloration, mucositis/stomatitis, asthenia, altered taste, and constipation. Dose reductions were required in 50% of the patients studied in RCC in order to manage the significant toxicities of this agent.