Maxfacts

Antiangiogenic medications

Angiogenesis is the growth of blood vessels. Antiangiogenic medications (also called angiogenesis inhibitors) are a group of substances which hinder the blood-vessel growth process in various different ways. When first discussed as a means to ‘starve’ malignant tumours by cutting off, or reducing tumour blood supply, some 50 years ago this was hailed as the new and bright era of cancer treatment.

Since then antiangiogenic medications have had a long and controversial history. An infamous example of a drug with antiangiogenic properties is thalidomide (which was responsible for foetal developmental defects because the antiangiogenic properties of the drug prevented the normal formation and growth of limbs in a foetus when given to pregnant women).

Antiangiogenic substances (of which there are many) work by blocking one, or several of the, proteins that initiate and carry through vascular growth. The medications are used topically (injected into the eye) for the treatment of the age-related eye-disease macula degeneration, and systemically in the treatment of several advanced malignancies (including colon, kidney, liver, thyroid and lung cancers, as well as some haematological malignancies). The most commonly used substances with antiangiogenic properties are

• bevacizumab (blocks a specific growth factor protein needed for endothelial (lining) growth of blood vessels, VEGF-A, that is particularly active in the angiogenesis of tumour tissues);
• sunitinib (blocks cellular messaging pathways for a number of growth factors, including some related to platelets and VEGF-A);
• sorafenib (blocks similar cellular mechanisms as sunitinib plus some specific kinase proteins).

The wanted beneficial effects of antiangiogenics on curbing tumour growth are very closely coupled with the clinical risks of their unwanted toxicities, typically with a very narrow therapeutic window. These unwanted effects can be serious and include severe bleeding, hypertension (high blood pressure), other cardiac risks (such as ischaemia (lack of blood supply) of the heart muscle).

In some instances, very good tumour control or even shrinkage achieved by angiogenesis inhibitors (usually in combination with other chemotherapy substances) have been reported. However, there are also reports with evidence that in some circumstances the enforced hypoxia (starving of oxygen) of tumour tissue may actually encourage metastasis, the spread of regional and distant malignancy. At least for the time being, the long and controversial history of antiangiogenics is bound to continue.

It is unlikely that antiangiogenic medications will be prescribed in a maxillofacial clinic. However, some of the unwanted effects of these drugs may need consultation and treatment in a maxillofacial clinic.