Sunitinib is a targeted therapy medication used to treat specific types of cancer. Sold under the brand name Sutent, it represents a modern approach to cancer care that differs from traditional chemotherapy. Instead of affecting all rapidly dividing cells, sunitinib attacks particular molecules involved in cancer cell growth, allowing it to disrupt tumor progression with a focused mechanism. The medication is taken orally as a capsule, offering a less invasive administration route compared to intravenous treatments.
How Sunitinib Works
Sunitinib is a multi-targeted tyrosine kinase inhibitor. Tyrosine kinases act as on/off switches for cellular functions like cell growth and division. In cancer, certain tyrosine kinases get stuck in the “on” position, causing uncontrolled cell multiplication. Sunitinib blocks these proteins, turning off the signal that tells cancer cells to grow, and targets several receptors at once, including PDGFR and KIT.
The drug also has anti-angiogenesis properties. Angiogenesis is the process where tumors form new blood vessels to supply themselves with oxygen and nutrients for survival. Sunitinib inhibits vascular endothelial growth factor receptors (VEGFRs), which are primary drivers of this process. By blocking these receptors, the medication helps cut off the tumor’s blood supply, which can slow its growth or cause it to shrink.
Cancers Treated by Sunitinib
Sunitinib is approved for treating specific cancers where its molecular targets are present. A primary use is for advanced renal cell carcinoma (RCC), a type of kidney cancer. It is used for patients with advanced disease and as an adjuvant therapy for those at high risk of recurrence after surgery.
Another indication is for gastrointestinal stromal tumor (GIST), a rare cancer of the digestive tract. It is prescribed for GIST patients whose tumors have not responded to the drug imatinib or for those who cannot tolerate it. Most GISTs are driven by mutations in the KIT receptor, one of sunitinib’s main targets. The medication also treats progressive, well-differentiated pancreatic neuroendocrine tumors (pNET) that are unresectable or have spread.
Common Side Effects and Management
Fatigue is one of the most frequently reported side effects and can impact daily life. To manage this, patients are advised to incorporate gentle exercise, such as short walks, and to schedule regular rest periods to conserve energy.
Digestive problems like diarrhea, nausea, and mouth sores (mucositis) are also common. For diarrhea, staying hydrated and eating bland, low-fiber foods can provide relief. Nausea can be managed with anti-nausea medications and by eating small, frequent meals. For mouth sores, good oral hygiene, using a soft-bristle toothbrush, and avoiding spicy or acidic foods can reduce discomfort.
Changes to the skin and hair are distinctive side effects. Many patients notice a yellowish skin discoloration, which is caused by the drug’s color and is not harmful. Hair can also lighten or lose its color. Another common issue is hand-foot syndrome, characterized by redness, swelling, and blistering on the palms and soles. Using thick, alcohol-free moisturizers, comfortable footwear, and avoiding prolonged hot water exposure can help manage these symptoms.
Serious Risks and Necessary Precautions
While many side effects are manageable, sunitinib carries risks that require careful medical supervision. High blood pressure (hypertension) is a potential issue, requiring regular checks and possibly medication to control it. The drug can also affect heart function, including a potential decrease in the heart’s ability to pump blood, measured as the left ventricular ejection fraction.
Liver toxicity is a risk, and patients will undergo routine blood tests to check liver function. Symptoms like yellowing of the skin or eyes, dark urine, or pain in the upper right abdomen should be reported to a doctor immediately. Thyroid function can also be affected, often leading to an underactive thyroid (hypothyroidism), which also requires monitoring through blood tests.
Patients on sunitinib must inform healthcare providers about all other medications being taken, as it can interact with drugs metabolized by the CYP3A4 enzyme. Grapefruit and grapefruit juice must be avoided because they interfere with this enzyme and increase the risk of toxicity. Because the drug can impair wound healing, doctors must also be informed before any planned surgical procedures.