Pazopanib is a prescription medication, sold under the brand name Votrient, used in the treatment of specific types of cancer. It belongs to a class of drugs known as targeted therapies, which interfere with molecules necessary for cancer growth. This represents a more focused approach to cancer treatment compared to traditional chemotherapy.
How Pazopanib Fights Cancer
Pazopanib functions as a multi-target tyrosine kinase inhibitor. Tyrosine kinases are proteins that act as on/off switches for cellular functions like cell growth and division. In many cancers, these switches are stuck in the “on” position, leading to uncontrolled cell proliferation. Pazopanib works by blocking the activity of several of these kinase proteins, including PDGFR and c-KIT, turning off the signals that tell cancer cells to multiply.
This medication also has anti-angiogenic properties. Angiogenesis is the process of forming new blood vessels, which tumors need to get oxygen and nutrients. Pazopanib inhibits key receptors, such as the vascular endothelial growth factor receptor (VEGFR), to help cut off the tumor’s blood supply. This can slow its growth and limit its ability to metastasize.
Approved Medical Uses
The U.S. Food and Drug Administration (FDA) has approved pazopanib for two primary conditions. The first is advanced renal cell carcinoma (RCC), the most common type of kidney cancer in adults. In RCC, malignant cells form in the lining of the kidney’s tubules, and “advanced” means the cancer has spread beyond the kidney.
The second approved use is for advanced soft tissue sarcoma (STS) in patients who have previously undergone chemotherapy. Soft tissue sarcomas are rare cancers that develop in the body’s soft tissues, such as muscles, fat, and tendons. These cancers are most common in the arms, legs, and abdomen. Physicians may also prescribe pazopanib for other conditions, a practice known as off-label use.
Administration and Patient Monitoring
Pazopanib is administered as an oral tablet, taken once daily. It is important that the medication be taken on an empty stomach, at least one hour before or two hours after a meal. Taking the drug with food can significantly increase its absorption, which may heighten the risk of side effects. If a dose is missed, it should be taken only if there are more than 12 hours until the next scheduled dose; otherwise, the missed dose should be skipped.
Consistent medical oversight is a standard part of treatment with pazopanib. Healthcare providers will frequently check blood pressure, as hypertension is a common side effect that often develops within the first few weeks of treatment.
Patients will also undergo routine liver function tests. These blood tests measure levels of enzymes and proteins like ALT and AST to ensure the liver is not being harmed, as hepatotoxicity is a known risk. Thyroid function tests may also be performed, as the medication can affect the thyroid gland’s ability to produce hormones. This comprehensive monitoring allows the medical team to manage side effects and make dose adjustments if necessary.
Potential Side Effects
Patients taking pazopanib may experience a range of side effects. The most frequently reported include:
- Diarrhea
- Fatigue
- Nausea
- Changes in hair color (lightening or depigmentation)
- High blood pressure
- Decreased appetite
- Changes in taste
- Abdominal pain
It is important for patients to communicate any of these effects to their healthcare provider.
Serious Side Effects
In some cases, pazopanib can cause more severe health issues that require immediate medical attention. One of the most significant risks is liver damage. Symptoms that could indicate a liver problem include yellowing of the skin or eyes (jaundice), unusual darkening of the urine, severe fatigue, or pain in the upper right abdomen.
Other serious potential side effects involve the cardiovascular system. These can include heart problems, such as an irregular heartbeat or symptoms of cardiac dysfunction, and an increased risk of blood clots or severe bleeding events. A rare but dangerous possibility is the formation of a hole in the stomach or intestines, known as gastrointestinal perforation. Any signs of these conditions, such as chest pain, shortness of breath, severe stomach pain, or unusual bleeding, should be reported to a doctor right away.