What is/are Sunitinib?
Sunitinib (marketed as Sutent by Pfizer, and previously known as SU11248) is an oral, small-molecule, multi-targeted receptor tyrosine kinase (RTK) inhibitor that was approved by the FDA for the treatment of renal cell carcinoma (RCC) and imatinib-resistant gastrointestinal stromal tumor (GIST) on January 26, 2006. Sunitinib was the first cancer drug simultaneously approved for two different indications.
Sunitinib has been generally well tolerated. Adverse events were 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, a 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.
Serious (grade 3 or 4) adverse events occur in ≤10% of patients and include hypertension, fatigue, asthenia, diarrhea, and chemotherapy-induced acral erythema. Lab abnormalities associated with sunitinib therapy include lipase, amylase, neutrophils, lymphocytes, and platelets. Hypothyroidism and reversible erythrocytosis have also been associated with sunitinib.
Most adverse events can be managed through supportive care, dose interruption, or dose reduction. The efficacy of the dose reduced sub-group has never been published.
Mechanism of action
Sunitinib inhibits cellular signaling by targeting multiple receptor tyrosine kinases (RTKs). These include all receptors for platelet-derived growth factor (PDGF-Rs) and vascular endothelial growth factor receptors (VEGFRs), which play a role in both tumor angiogenesis and tumor cell proliferation. The simultaneous inhibition of these targets therefore leads to both reduced tumor vascularization and cancer cell death, and ultimately tumor shrinkage.
Sunitinib also inhibits KIT (CD117), the RTK that (when improperly activated by mutation) drives the majority of gastrointestinal stromal cell tumors. It has been recommended as a second-line therapy for patients whose tumors develop mutations in KIT that make them resistant to imatinib, or who become intolerant to the drug.
In addition, sunitinib inhibits other RTKs. These include:
The fact that sunitinib targets many different receptors, leads to many of its side effects such as the classic hand-foot syndrome, stomatitis, and other dermatologic toxicities.
This article uses material from the Wikipedia article Sunitinib, which is released under the Creative Commons Attribution-Share-Alike License 3.0.