Age-related macular degeneration (AMD) is a common disease of the central retina and remains a leading cause of vision loss and blindness in elderly Americans. Currently, the standard of care for wet-AMD is intravitreal vascular endothelial growth factor (VEGF) inhibitors. However, these therapies are not always effective in all patients. AMD is a multi-factorial disease involving numerous pathogenic factors that contribute to the pathogenesis of AMD. Thus, targeting a VEGF or VEGF receptors alone cannot benefit all cases of AMD, and there is a great demand for developing more effective therapeutic options with multiple targets or new targets. Accumulated evidence has demonstrated that the over-activation of Wnt pathway plays an important role in AMD. The Wnt pathway is involved in multiple pathological processes of AMD, including the formation of new blood vessels, vascular leakage, inflammation, fibrosis and oxidative stress, as it regulates many Wnt target genes which are known pathogenic factors, e.g. VEGF, platelet-derived growth factor (PDGF), intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-alpha (TNF-a), cyclooxygenase-2 (Cox-2), connective tissue growth factor (CTGF), and fibronectin (FN). Since Wnt inhibitors can simultaneously down- regulate multiple pathogenic factors, they should be more superior to anti-VEGF therapeutics. Low-density lipoprotein receptor-related protein 6 (LRP6), a cell surface receptor, is an essential component for the activation of the Wnt pathway. Thus, LRP6 becomes an attractive molecular target for treating AMD. Through generating and screening a series of mouse anti-human LRP6 monoclonal antibodies (mAbs), 2F1mab has been identified as a specific mAb against human LRP6 and a potent Wnt inhibitor. Preliminary data showed that 2F1mab specifically recognizes the ligand-binding domain of LRP6, blocks the over- activation of Wnt pathway, down-regulates the over-expression of WNT target genes including VEGF, TNF-a, ICAM-1 and CTGF, and alleviates multiple pathological processes of AMD such as retinal vascular leakage, inflammation and neovascularization (NV). As AMD is characterized by multiple pathological processes, the inhibitory effects of 2F1mab on multiple pathogenic factors make it a promising drug candidate for the treatment of AMD. The therapeutic potential of 2F1mab strongly warrants further development of an antibody - based therapy modality which is suitable to clinical use in AMD patients. Using complementarity-determining region (CDR) grafting, phage display techniques and antibody expression system, we have produced a series of humanized antibodies. Among them, clone CLT-020 showed high affinity to human LRP6 and potent inhibitory effect on the Wnt pathway, corneal neovascularization and information. These findings indicate that CLT-020 is a promising drug candidate for AMD. This SBIR Phase I project will serve as a proof-of-concept study to evaluate the in vivo efficacies of CLT- 020 on Wnt signaling activation, Wnt target gene expression and chroidal neovascularization (CNV) in a rat model of laser-induced CNV. The program includes two specific aims:
Aim 1 will determine the effects of CLT- 020 on the Wnt pathway activation and Wnt target gene expression.
Aim 2 will evaluate the efficacies of CLT- 020 on CNV. The proposed studies will lay a solid groundwork for future preclinical studies of CLT-020 in Phase II. The project has potential to develop a therapy with a novel target other than VEGF to treat AMD. This new therapeutic antibody could be applied together with anti-VEGF agents or as an alternative.
Age-related macular degeneration (AMD) remains a leading cause of vision loss and blindness in elderly Americans. Current therapies have limited benefit and are not always effective in all patients with AMD. Thus, there is a great demand for developing more effective alternative options to improve the treatment of AMD. The project will develop a treatment with a novel target other than VEGF to treat AMD.
