Abstract
Tay-Sachs disease (TSD) is a rare autosomal recessive genetic disorder resulting from mutations in the lysosomal enzyme, β-hexosaminidase A. Deficiency of the enzyme activity leads to excessive accumulation of GM2 ganglioside in the CNS and rapid, progressive neurodegeneration. Currently there are no treatments available and patients affected with the severe infantile form of Tay-Sachs do not live beyond 2-4 years of age. Enzyme replacement therapy is not a therapeutic option due to its inability to cross the blood brain barrier. Specifically targeting restoration of the defective enzyme activity with pharmacological chaperones has failed to show efficacy in clinical trials in Tay-Sachs patients. Patient derived phenotypic assays offers an alternative to target based strategies which have failed to deliver effective treatments. We developed a high throughput assay with infantile Tay-Sachs patient derived cells based on a pathophysiological feature of disrupted lysosomal calcium signaling as a monitor of diseased phenotype to identify compounds that could reverse or attenuate the disease as a novel approach to discover disease modifying therapeutics. In proof of concept studies, we demonstrated that the phenotypic assay was sensitive to treatment with pyrimethamine, a pharmacological chaperone of the defective β-hexosaminidase enzyme. The HTS assay was validated in a pilot screen with a collection of 1200 known FDA approved drugs with active compounds identified. Actives were further characterized for functional potency and selectivity for diseased vs non-affected patient derived cells. The establishment of this high throughput screening assay in patient derived cells will enable screening of larger chemical compound collections. Importantly, this approach could lead to identification of new molecular targets previously unknown to impact the disease and accelerate discovery of new treatments for Tay-Sachs disease.