Activators of the tissue-protective erythropoietin receptor (EPOR/?c) demonstrate encouraging pre-clinical and early clinical results for the treatment of Friedreich?s Ataxia and Parkinson?s disease and hold significant potential for expansion to additional indications. In preliminary studies, a small molecule scaffold was identified that increased the binding of EPOR extracellular 25-250 193-216 domain (EPOR ) and a fluorescently-labeled peptide corresponding to EPOR . SAR optimization of this scaffold produced a small molecule library of both ?active? and ?inactive? molecules based on activation of EPOR/?c, activation of canonical signaling molecules, cytoprotection in cell-based assays and ability to increase frataxin protein in vitro and in vivo. The central goal of this Phase 1 SBIR Proposal is to establish a homogeneous, high-throughput receptor-domain interaction assay capable of identifying and ranking small molecule activators of EPOR/?c. The key objectives are to (1) evaluate fluorescence-polarization, FRET/HTRF and Alpha methodologies to demonstrate association of peptide/receptor and receptor domains in solution, (2) demonstrate increased association of peptide/receptor and receptor domains in the presence of validated small molecule activators of EPOR/?c and (3) demonstrate that the assay is capable of discriminating between validated ?active? and ?inactive? small molecules in a proprietary small molecule library. If successfully established, this assay would be used to support (1) lead-optimization of known receptor-activating scaffolds and (2) a high-throughput screen to identify new receptor activating scaffolds with follow-on optimization. The latter studies would be the subject of a future Phase II application, which would also include an assessment of small molecule binding site(s), receptor activation, cytoprotective activity and the ability of these small molecules to increase frataxin protein.
Preclinical and early clinical studies suggest that activators of the tissue-protective erythropoietin receptor have significant potential for the treatment of Friedreich?s Ataxia and Parkinson?s disease, where the discovery of selective, orally bioavailable small molecules is urgently needed. The development of small molecule screens for erythropoietin receptor has been technically challenging and slow, while studies of new binding interactions that mediate receptor activation have demonstrated promising preliminary success for identifying drug-like ?hit? compounds that supported lead optimization for selectivity in tissue protection, bioavailability in brain and other tissues, and efficacy in relevant disease models. This proposal focuses on developing a homogeneous high-throughput assay for the discovery of such molecules based on these studies.
