Drug Repurposing Screening for Rare and Neglected Diseases

National Center For Advancing Translational Sciences

Investigators

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Abstract

In collaboration with NIH and external academic researchers, we have carried out assay development and performed drug repurposing screens for multiple projects across a range of therapeutic areas, including drug resistant bacteria and fungi, rare genetic disorders, and drug resistant rare cancer. INFECTIOUS DISEASES: Infections with multidrug-resistant (MDR) organisms have emerged as a significant worldwide public health crisis. The incidence is increasing, partially due to the selective pressure from widespread use of antibiotics in both humans and animals. One such fungal species, Candida auris, is responsible for several outbreaks in hospitals and care facilities. We have performed high throughput screening to identify individual drugs and synergistic drug combinations active against multidrug-resistant Candida auris. A set of approved and investigational drugs have been identified and the mechanisms of action were explored (Cheng Y-S et al., Antimicrob Agents Chemother. 65: e01305-20). The mammarenavirus Lassa (LASV) infects several hundred thousand individuals annually in Western Africa and causes high morbidity and significant mortality. It is a neglected human pathogen of clinical significance without effective vaccines and therapeutics. We performed a high throughput screen that identified a set of inhibitors of viral replication. The identified compounds are undergoing further studies and the compound screening data have been published (Cubitt B. et al., Antiviral Res 173, 104667). DRUG RESISTANT CANCER: Cancer drug resistance is a severe clinical problem that often results in patient death. We performed drug repurposing screens for drug-resistant cell lines of liver cancer and ovarian cancer refractory to multiple standard care chemotherapies. Several approved drugs have been identified that either suppress the drug-resistant cancer cells directly or re-sensitize the resistant cells to the anticancer activities of the standard drugs. We also found that diverse mechanisms are involved in cancer drug resistance, indicating the importance of personalized treatment which can be obtained from personalized drug screens using patient-derived cancer samples. The results have been published recently (Li J. et al., Cell Death Dis. 12: 341; Martin SP. et al, J Exp Clin Cancer Res 39: 99; Xu L et al., Signal Transduct Target Ther 5: 298) LYSOSOMAL STORAGE DISEASES and GENETIC DISEASES: Tay-Sachs and Sandhoff diseases are lysosomal storage disorders that exhibit the lysosomal accumulation of GM2 gangliosides due to deficiency of the beta-hexosaminidases Hex-A or Hex-B. We evaluated in vitro the cellular uptake, intracellular delivery to lysosome, and reduction of stored substrates by the recombinant human Hex-A and Hex-B. The enzymes entered cells via the endocytic pathway mediated by mannose and mannose-6-phosphate receptors to lysosomes and effectively reduced the disease phenotypes in the patient cells (Espejo-Mojica AJ et al., Am J Med Genet C Semin Med Genet 184: 885-895). We also developed a patient iPS cell-based disease model for Pompe disease, a lysosomal storage disorder caused by autosomal recessive mutations in the acid alpha-glucosidase gene. The deficiency of this enzyme causes abnormal glycogen accumulation in patient cells and various clinical symptoms including the neuronal symptoms. We employed and validated neural stem cells differentiated from Pompe patient iPS cells to model the neuronal phenotype of Pompe disease which can be used to study disease pathogenesis, to evaluate drug efficacy, and to screen compounds for drug discovery (Cheng YS et al., Cells 10: E8). We have previously developed mass spectrometry-based methods for the detection of creatine and phosphocreatine in Creatine Transporter Deficiency patient fibroblasts. We are working with Dr. Forbes Porter to establish a relationship between patient genotypes, behavioral measurements, and creatine uptake. We have also worked on the drug repurposing screens for several other genetic diseases and published the experimental results including RHO-associated retinitis pigmentosa (Liu X et al., FASEB J 34: 10146-10167), Huntington disease (Khaled HG et al, Sci Rep 11: 6157), and for fibrodysplasia ossificans progressiva (Willams EP et al., JCI Insight. 6: 95042). ASSAY TECHNOLOGY AND iPS CELL LINES FOR DISEASE MODELING: We have developed a mass spectrum-based compound screening assay for the NGLY1 deficiency project. This assay measures human Engase (a target for NGLY1 therapeutic development) activity that can be used for compound screening (Tao D et al., Talanta. 231: 122384: 122384). We also developed a cell-based compound screening assay technology using a fluorescence cytometry plate reader that allows performing cell-based compound screening assays in homogeneous assay format without a need of plate wash (Gorshkov K et al., J Pharmacol Exp Ther 374: 500-511). For better modeling diseases for drug development, we have generated several patient derived iPS cell lines that have been characterized and stably passaged over 10 passages. These patient iPS cell lines can be further differentiated into different cell types and organoids for disease modeling and compound screening for drug development.