Predictive biomarkers and new therapeutic targets for Age-related Macular Degeneration (AMD)

AMD is a degenerative disease of the retina leading to a loss of visual function. It is one of the principal causes of visual impairment in the world and the leading cause of blindness in developed countries.

Progression of AMD can lead to two distinct clinical manifestations of late AMD. The dry or atrophic form of AMD is more frequent and is characterized by the accumulation of small drusen in the retinal pigment epithelium (RPE) leading to a loss of RPE and a degeneration of the retina in the macular region. It results in a mild loss of visual function. The wet neovascular form is less common but causes serious loss of vision. It is characterized by neovascular “membranes” derived from the choroidal vasculature that invade Bruch´s membrane, leak, and often cause detachments of the RPE and/ or the neural retina. The newly formed capillaries are abnormally permeable and their leakage leads to a scarring of the macula leading to blindness. Dry AMD may develop into wet AMD within several months.

Current therapy options

Wet AMD is an age-related disease associated with overexpression of vascular endothelial growth factor (VEGF), as well as the deposition of drusen in the sub-RPE and a breakdown of the RPE and the Bruck’s membrane. VEGF is a key regulator of physiological and pathological angiogenesis and has been in the focus of research as therapeutic target in the last years. It leads to the growth of newly formed blood vessels from the choroid through the RPE into the retina. Leakage of blood or plasma into the surrounding tissue can be hampered by therapy using anti-VEGF antibodies. There have been significant advances in the management of exudative or so-called wet age-related macular degeneration with the introduction of anti-angiogenesis therapy via inhibition of vascular endothelial growth factor (VEGF). Inhibition of VEGF via repetitive intraocular injection of anti-VEGF antibodies over several years has become the gold standard in the treatment of wet AMD. Patients who suffer from wet AMD now have early treatment options that can prevent blindness and, in many cases, restore vision. However, these treatments are very expensive, and in our own studies we found that many patients do not respond to this kind of therapy.

Predictive targets: Companion Diagnostic Test

In several clinical studies, we were able to detect autoantibodies that are differentially regulated in AMD patients responding to anti-VEGF-treatment compared to non-responding patients who continue to lose their vision. These altered autoantibody profiles allow us to predict whether a patient will respond to treatment with anti-VEGF or not.

Based on these results we are developing a saliva-based diagnostic lateral flow assay (LFA) for AMD based on these altered autoantibody profiles, as a „Companion Diagnostic“ to guide subsequent treatment decisions.

„The new predictive Companion Diagnostic Test builds the basis for a new personalized treatment option for AMD“

Key points:

  • Age-related macular degeneration (AMD) is one of the main causes of visual impairment and blindness
  • The loss of vision associated with AMD may range from mild to acute.
  • Treatment may be guided by an accurate prognosis, to avoid, for example, the use of expensive anti-VEGF treatment in non-responders (companion diagnostics).
  • Biomarkers (autoantibodies) have been identified that permit:
    • the response to anti-VEGF treatment in the case of wet AMD.
    • the classification of AMD into the wet and dry forms.

Our goals for AMD diagnostic:

  • to predict responsiveness of an individual with wet AMD to treatment with a VEGF antagonist (so called anti-VEGF non-responder)
  • to develop a companion diagnostic assay to enable early and personalized treatment adjustments, especially for non-responders
  • to diagnose and distinguish dry and wet AMD
  • to determine the risk of conversion of a dry AMD disease to a wet AMD disease.
  • to evaluate our quick, non-invasive and easy to use POC device
  • to develop software to analyse the signals for the different autoantibodies, without user error.

Goals (sampling)

AMD biomarker autoantibodies may be found in both tears and blood. Blood has evident disadvantages in terms of sample preparation prior to testing. In addition, high protein concentrations seriously affect assay sensitivity and are a constant problem for blood-based assays. At maintect GmbH, we have been developing a saliva-based sampling system which, although potentially suffering from problems of viscosity due to the mucins present, offers advantages by being quick and non-invasive. The system we are developing permits partial neutralization of the inhibition exerted by saliva on the test line signal.

Goals (treatment):

Antibodies present, or not, in dry or wet AMD are promising targets to be tested as new therapeutic options for non-responders to current treatment options. This applies not only to whole antibodies, but also to appropriate paratope sequences (CDR-sequences) of the antibody of choice or other related drug targets in the pathways influenced by those marker molecules found in both clinical trials. Paratope sequences could be sequenced and synthesized more easily and would offer a more cost-effective alternative to antibody treatment. Thus, the immunological changes determined in AMD patients offer a way to personalize therapy in order to offer each patient the most promising treatment.

New personalized AMD therapy

Furthermore, we plan to bring forward the development of a new therapeutic approach for those anti-VEGF-non-responders, but also as a general new therapeutic option for wet AMD and dry AMD. In vitro and in vivo tests with our molecule of choice have generated very promising results and target a completely new therapeutic pathway.

  • Franz Grus, Christina Korb, Norbert Pfeiffer. Predictive Markers Useful in the Treatment of Wet Age- Related Macular Degeneration. Patent US2019072550 (A1).