Vandetanib is a medication classified as a kinase inhibitor used in cancer treatment. It targets certain proteins within the body to manage specific types of cancer. This oral therapy represents a targeted approach to addressing disease progression.
How Vandetanib Functions
Vandetanib operates as a multi-kinase inhibitor, interfering with the activity of several enzymes (kinases) that play roles in cell growth and survival. It primarily targets the vascular endothelial growth factor receptor (VEGFR), epidermal growth factor receptor (EGFR), and RET-tyrosine kinase pathways. These pathways are often overactive in cancer cells, promoting uncontrolled growth and the formation of new blood vessels (angiogenesis).
By blocking VEGFR, Vandetanib reduces the blood supply necessary for tumor growth. Its action on EGFR disrupts signals that drive cancer cell proliferation. Inhibiting RET tyrosine kinases, which are frequently mutated in specific cancers, directly interferes with a key driver of disease progression. This multi-targeted approach aims to slow tumor growth and spread.
Conditions Treated by Vandetanib
Vandetanib is primarily used for the treatment of symptomatic or progressive medullary thyroid cancer (MTC) that is unresectable or metastatic. Unresectable means the cancer cannot be removed by surgery, while metastatic indicates it has spread from the thyroid to other parts of the body. MTC is a rare form of thyroid cancer originating from parafollicular C cells in the thyroid gland, which produce calcitonin.
This type of cancer accounts for 1% to 5% of all thyroid cancers. While most cases occur sporadically, about 25% are hereditary and linked to multiple endocrine neoplasia type 2 (MEN2). Vandetanib offers a systemic treatment option for patients with advanced MTC when surgery is not an option.
Administering Vandetanib
Vandetanib is administered as an oral tablet, taken once daily. Patients can take the medication with or without food, but it is recommended to take it at the same time each day. The tablet should be swallowed whole; do not crush or chew it.
If a patient has difficulty swallowing, the tablet can be dispersed in a small amount of non-carbonated water, stirred for about 10 minutes until it breaks into small pieces, and then consumed immediately. If a dose is missed, take it as soon as remembered, unless it is less than 12 hours before the next scheduled dose, in which case skip the missed dose. Do not take a double dose to compensate.
Understanding Potential Effects
Vandetanib can lead to various effects, some common and others serious, requiring careful monitoring. Common effects include high blood pressure, diarrhea, skin rash, fatigue, nausea, headache, and decreased appetite. Diarrhea and skin reactions are common, and skin sensitivity to sunlight can occur, necessitating protective clothing and sunscreen for up to four months after treatment ends.
More serious effects include changes in heart rhythm, specifically QT prolongation, which can lead to irregular heartbeats. Regular electrocardiograms (ECGs) and monitoring of electrolyte levels (potassium, calcium, magnesium) are performed before and during treatment. Severe skin reactions, such as Stevens-Johnson syndrome, and interstitial lung disease (ILD), a serious lung condition, have also been reported. Patients should seek immediate medical attention for symptoms like sudden shortness of breath, severe skin blistering, or signs of stroke. Vandetanib is available through a restricted distribution program due to the potential for serious effects.