Use of Avastin in age-related macular degeneration (AMD) January, 2007
Angiogenesis, the growth of new blood vessels from existing blood vessels, is responsible for vision loss in a variety of ophthalmic diseases. In neovascular age-related macular degeneration (AMD), the leading cause for legal blindness in many industrialised countries, abnormal blood vessels grow in the macula and cause blindness. [A2]
A fully alert 83-year-old woman with occult choroidal neovascularization (CNV) left eye (OS) experienced a progressive visual loss to 20/800 OD and 20/400 OS. Another patient with occult CNV both eyes (OU) experienced decreased vision of 20/800 OU.
One day and three days After the injection of 1.25 mg Avastin in the left eyes of both patients, they both experienced structured hallucinations including trees, faces, and water for approximately 15 to 30 minutes. [A1]
The researchers believed that the reduced retinal edema and realignment of the photoreceptors promoted the release phenomenon and triggered hallucinatory episodes. [A1]
WHAT IS AVASTIN? Avastin-first line treatment for patients with metastatic colorectal cancer- is a genetically engineered version of a mouse antibody that contains both human and mouse components. (Antibodies are substances produced by the body's immune system to fight foreign substances.) Avastin was shown to extend patients' lives by about five months when given intravenously as a combination treatment along with standard chemotherapy drugs for colon cancer. However, Avastin will not cure metastatic colorectal cancer.
MECHANISM Avastin works by targeting and inhibiting the function of a natural protein called "vascular endothelial growth factor" (VEGF) that stimulates new blood vessel formation. When VEGF is targeted and bound to Avastin, it cannot stimulate the growth of blood vessels, thus denying tumors blood, oxygen and other nutrients needed for growth.
SAFETY AND EFFICACY The safety and efficacy of Avastin was primarily shown in a randomized, double-blind clinical trial of more than 800 patients with metastatic colorectal cancer designed to find out whether Avastin extended the lives of patients. Overall, patients given Avastin in combination with IFL survived about five months longer and the average time before tumors started regrowing or new tumors appeared was four months longer than patients receiving IFL alone. The overall response rate to the treatment was 45% compared to 35% for the control arm of the trial.
Special Warning and Side Effects of Avastin: Avastin may cause gastrointestinal perforation (holes in the stomach, intestines or colon) requiring surgery to repair. Avastin may impair wound healing or cause wounds to open up. Avastin may cause severe infusion reactions such as trouble breathing during the first or later doses.
Other, more common, side-effects are high blood pressure, tiredness, blood clots, diarrhea, decreased white blood cells (lowering immunity to diseases) headache, appetite loss and mouth sores. MORE ABOUT AVASTIN
Reference [A1] Meyer CH, et al, Visual Hallucinations After Intravitreal Injection of Bevacizumab in Vascular Age-related Macular Degeneration. Am J Ophthalmol. 2007 Jan;143(1):169-170. Epub 2006 Sep 7. [A2] Michels S et al, Promising new treatments for neovascular age-related macular degeneration. Expert Opin Investig Drugs. 2006 Jul;15(7):779-93.