gms | German Medical Science

Since a couple of years, the antibody bevacizumab (Avastin™) and the antibody fragment ranibizumab (Lucentis™) have been applied successfully in patients suffering from \'22wet\'22 AMD and other neurovascular eye diseases. The antibody fragment ranibizumab was developed under the assumption that complete antibodies would not be able to penetrate the retina due to their size in order to reach the site of their action, the subretinal space. However, facing the clinical success of the off-label use of Avastin™, this assumption was challenged. Recently, we could show by immunohistochemical staining that bevacizumab actually penetrates the retina after an intravitreal injection of Avastin™ in monkeys. Bevacizumab is taken up by several cell in the retina, in particular by photoreceptors, where it can be detected in the outer segments. Intravitreally injected bevacizumab could also be detected already one day later in the systemic blood circulation, as well as in choroidal blood vessels, starting from day one after injection, and increasingly later on. As bevacizumab penetrated the retina, no more VEGF could be detected in the penetrated area. In the meantime, we are also able to study ex vivo the retinal penetration of the antibody fragment ranibizumab by establishing an immunohistochemical detection method for ranibizumab in our lab. This way, we found that also ranibizumab is taken up by several neuronal cells in the retina.