Anti-vascular endothelial growth factor (anti-VEGF) therapy is a treatment that inhibits a protein called vascular endothelial growth factor (VEGF). This protein is central to angiogenesis, the formation of new blood vessels. The primary goal of this therapy is to slow or stop the development of abnormal blood vessels or reduce leakage from these vessels where they contribute to disease.
This treatment is a widespread intervention in ophthalmology and oncology for diseases characterized by excessive blood vessel growth. By interfering with the VEGF protein, these therapies can slow disease progression and, in some cases, partially reverse damage.
Understanding Vascular Endothelial Growth Factor (VEGF)
Vascular Endothelial Growth Factor (VEGF) is a naturally occurring protein that stimulates blood vessel formation. It has beneficial roles, particularly during embryonic development in creating the circulatory system. In adults, VEGF is important for wound healing and creating new blood vessels when tissues are deprived of oxygen or after an injury.
While necessary for normal functions, an overabundance of VEGF can cause the growth of abnormal, weak, and leaky blood vessels. These vessels can leak fluid, bleed, or interfere with the normal function of tissues, such as the retina or a growing tumor. This recognition of VEGF’s role has made it a target for therapies that control its effects to mitigate damage.
Mechanism of Anti-VEGF Drugs
Anti-VEGF medications counteract the effects of vascular endothelial growth factor. These drugs function by binding directly to VEGF proteins or by blocking the cellular receptors that VEGF attaches to. This action neutralizes the growth factor, preventing it from stimulating new blood vessel formation or increasing their permeability.
The medications are often monoclonal antibodies or other engineered molecules. Some are full-sized antibodies, while others are smaller antibody fragments developed for applications like injection into the eye. Orally administered drugs are also available that work by inhibiting the tyrosine kinase enzymes stimulated by VEGF, blocking the signal from within the cell.
By interrupting this signaling pathway, anti-VEGF drugs reduce the growth of the abnormal blood vessels that contribute to certain diseases. This helps to slow down leakage, reduce swelling, and prevent further damage caused by the proliferation of these vessels.
Conditions Treated by Anti-VEGF Therapy
Anti-VEGF therapy is a standard treatment for several conditions, primarily in ophthalmology and oncology. In eye diseases, it addresses abnormal blood vessel growth in the retina, while in oncology, it restricts the blood supply that tumors need to grow.
For ophthalmic diseases, this therapy is used to treat:
- Wet age-related macular degeneration (AMD), to control the growth of new, leaky blood vessels under the retina.
- Diabetic macular edema (DME), where fluid leaks into the macula, causing swelling and vision loss.
- Macular edema resulting from retinal vein occlusion (RVO).
- Myopic choroidal neovascularization, a complication of severe nearsightedness.
In oncology, anti-VEGF drugs are used for several advanced cancers, including metastatic colorectal cancer, non-small cell lung cancer, and renal cell carcinoma. By inhibiting tumor angiogenesis, the therapy limits a tumor’s access to oxygen and nutrients, which can slow its growth. This treatment is often used in combination with chemotherapy.
Receiving Anti-VEGF Treatment
The administration of anti-VEGF therapy depends on the condition being treated. For eye diseases, medication is delivered by an intravitreal injection directly into the eye. The eye is first numbed with anesthetic drops, and a small device may be used to keep the eyelids open. The injection uses a very fine needle and takes only a few seconds, with patients receiving a series of injections over many months.
For cancer treatment, anti-VEGF drugs are administered systemically through an intravenous (IV) infusion. These infusions are given in cycles, with the frequency and duration depending on the type of cancer and the overall treatment plan.
Treatment schedules are tailored to the individual. A patient with an eye condition might start with monthly injections, with the interval extending as the condition stabilizes. For cancer, the therapy is often integrated with other treatments like chemotherapy, requiring careful coordination.
Monitoring and Potential Side Effects
Healthcare providers monitor patients to assess treatment effectiveness and manage side effects. For ophthalmic conditions, monitoring involves regular eye exams, vision tests, and imaging like Optical Coherence Tomography (OCT). In oncology, progress is tracked through imaging scans such as CT, MRI, or PET scans, along with blood tests and a review of symptoms.
Side effects depend on how the drug is administered. Intravitreal injections for eye conditions can cause local side effects like eye pain, redness, floaters, and temporary blurred vision. Rare but more serious risks include eye infections, retinal detachment, or an increase in intraocular pressure.
Systemic administration for cancer can cause hypertension, an increased risk of bleeding, and impaired wound healing. Less common but more serious complications can involve blood clots or gastrointestinal issues. Patients should report any concerning symptoms to their medical team, as many side effects can be managed.