New perspectives: role of sunitinib in breast cancer.

Sunitinib malate (SU11248) is a multitarget oral tyrosine kinase receptor (RTKs) inhibitor which was approved by FDA in renal cells carcinoma (RCC) and imatinib-resistant or imatinib-intollerant gastrointestinal stromal tumour (GIST). Sunitinib is able to inhibit RTKs such as receptors for platelet-derived growth factor (PDGF-R alpha and beta) and for vascular endothelial growth factor (VEGFRs). It is able to inhibit KIT receptor, colony stimulating factor type 1 receptor (CSF- 1R), glial cell line neutrophic factor receptor (RET), fms-like tyrosine kinase receptor-3 (FLT-3 or CD135), signal transducer and activator of transcription 3 (STAT3) and AKT (protein kinase B) in tumour cells. Many sunitinib targets play important roles in growth and survival of human breast cancer (BC). The "rationale" of sunitinib in BC (with or without others antiagiogenetic therapy) is its ability to block simultaneously intracellular portion of RTKs inhibiting many downstream signals. We overviewed the most relevant studies concerning sunitinib in metastatic BC.