Angiogenesis is a natural biological process where new blood vessels form from existing ones. This process is involved in normal body functions like wound healing and supplying oxygen and nutrients to tissues. However, in certain disease states, it can become dysregulated, leading to abnormal blood vessel growth. Angiogenesis inhibitors are medications designed to block this formation of new blood vessels, targeting conditions where uncontrolled blood vessel growth contributes to disease progression.
How Angiogenesis Inhibitors Work
Angiogenesis inhibitors interfere with specific biological pathways that promote blood vessel growth. A primary target is vascular endothelial growth factor (VEGF), a signaling protein that stimulates new blood vessel formation. These inhibitors can either bind directly to VEGF, preventing it from activating its receptors, or block the receptors on the surface of endothelial cells, which line blood vessels.
Disrupting this VEGF pathway, or other related signaling cascades, effectively “starves” abnormal tissues, such as tumors, of the blood supply they need to grow. Without sufficient oxygen and nutrients, the growth and spread of these abnormal cells are significantly impeded. This mechanism differs from traditional treatments that directly kill cells, as angiogenesis inhibitors focus on cutting off their life support system.
Therapeutic Applications
Angiogenesis inhibitors are utilized in treating diseases characterized by excessive or abnormal blood vessel growth. A major application is in cancer therapy, where tumors require a sufficient blood supply to grow, invade surrounding tissues, and metastasize. By hindering new blood vessel development, these inhibitors can slow tumor growth, reduce tumor size, and potentially prolong patient survival. They are often used in combination with other cancer treatments like chemotherapy.
Beyond oncology, these inhibitors also play a role in managing specific eye conditions, particularly age-related macular degeneration (AMD). In the “wet” form of AMD, abnormal, leaky blood vessels grow under the retina, causing fluid leakage, bleeding, and scarring that can severely impair vision. Injecting angiogenesis inhibitors directly into the eye can suppress this abnormal vessel growth, helping to preserve or improve vision. Other conditions involving abnormal angiogenesis, such as certain skin diseases or diabetic ulcers, are also being researched for these therapies.
Common Inhibitor Categories and Administration
Angiogenesis inhibitors fall into different categories based on their molecular structure and how they exert their effects. One major category includes monoclonal antibodies, which are laboratory-produced proteins designed to mimic the body’s own immune system. These antibodies, such as bevacizumab, work by specifically binding to and neutralizing growth factors like VEGF in the bloodstream, preventing them from interacting with their receptors on blood vessel cells.
Another category comprises small molecule inhibitors, which are synthetic compounds that can pass into cells and block specific enzymes or receptors involved in angiogenesis signaling pathways, such as tyrosine kinase inhibitors (TKIs) like sunitinib. These inhibitors are administered through various routes depending on the drug and the condition being treated. Common methods include intravenous infusions, oral pills, and direct injections into specific areas like the eye for ophthalmic conditions.
Patient Considerations During Treatment
Patients undergoing treatment with angiogenesis inhibitors may experience side effects, which differ from those associated with conventional chemotherapy because these drugs target blood vessels rather than directly killing cells. Common side effects include elevated blood pressure, fatigue, and issues with bleeding or wound healing. Some patients might also notice protein in their urine.
These side effects are managed through close monitoring and supportive care from healthcare providers. For instance, high blood pressure can be controlled with medication, and fatigue may be addressed with lifestyle adjustments. Regular check-ups and laboratory tests are important to monitor a patient’s response to treatment and to identify and manage any emerging side effects.