P3‐138: Development of IPSC‐Based Biomarkers to Identify the Patient Population Responsive to Allopregnanolone

Alzheimer’s disease (AD) is a national and global epidemic with complex pathoetiology including compromised brain metabolic activity and decreased regenerative capacity. Allopregnanolone (Allo) is an investigational neuroregenerative therapeutic, currently in Phase 1b clinical trial for AD (NCT02221622, https://clinicaltrials.gov/ct2/show/NCT02221622?term=NCT02221622&rank=1). In rodent preclinical models, Allo promotes neural stem cell (NSC) proliferation and neural differentiation and improves mitochondrial function. To develop biomarkers to predict regenerative response to Allo, we have initiated proof of concept analyses to determine the impact of Allo on human induced pluripotent stem cells (iPSCs) and iPSC-derived neural cells. T-cells from a patient with familial AD due to the A431E presenilin-1 point mutation were reprogrammed via a non-integrating, non-viral method, to iPSCs. Additional iPSCs were provided by the University of California Irvine Alzheimer’s Disease Research Center (UCI-ADRC) and the Institute for Memory Impairments and Neurological Disorders. Isogenic iPSCs were generated using CRISPR-Cas9. Using dual inhibition of SMAD signaling, iPSCs were differentiated to NSCs. Mitochondrial respiration and regenerative capacity were determined using metabolic analyzer and FACS. Mitochondrial respiration and proliferation analyses were conducted in AD-derived and healthy control iPSCs and NSCs. Initial data indicates that AD iPSCs have similar proliferation rates, but increased ATP production compared to healthy controls. Analyses were conducted to determine the regenerative and bioenergetic effect of Allo. In iPSC-derived NSCs, Allo increased basal mitochondrial respiration by 78% and maximal mitochondrial respiratory capacity by 35%. Initial data indicate that iPSCs from AD patients demonstrate a metabolic phenotype distinct from healthy controls and that Allo improves mitochondrial function of iPSC-derived NSCs. Going forward the effect of Allo on the regenerative capacity and metabolic phenotype of iPSC-derived NSCs will be evaluated. These data will form the foundation for developing the first regenerative biomarker to determine and monitor response to therapeutics. Research supported by NIH National Institute on Aging U01AG031115 and UF1AG046148 to RDB; NIH/NINDS R00-NS07743 and the Donald E. and Delia B. Baxter Foundation to JKI; NIH National Institute on Aging AG005142 to HCC; UCI-ADRC funded by NIH/NIA Grant P50 AG16573; USC Provost Fellowship, CIRM Predoctoral Research Traineeship, and American Foundation for Pharmaceutical Education Fellowship to CMS.