Mature brain organoid platform for therapeutic screening for ALS/FTD

Abstract Synapticure is developing a novel patient-derived 3D platform for high-fidelity modeling and screening of TDP- 43 proteinopathy and associated biomarkers for amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Synapticure’s mature brain organoids (mbOrgs) are composed of key neural cells derived from patient- induced pluripotent stem cells (iPSCs) and are custom assembled into human brain co-cultures, allowing them to recapitulate several ALS/FTD disease features not seen comprehensively in any existing in vitro models. Conservatively, 16,000 Americans are affected by ALS, while up to 30,000 suffer from FTD, and the morbidity and cognitive and physical impairments are significant. Currently, effective diagnostics and treatments for ALS and FTD are lacking, and newer therapies have translated poorly to humans, despite showing great promise in in vitro and in vivo preclinical studies. Accurate models of both diseases are critically needed to advance the development of novel biomarkers, diagnostic/prognostic tools, and therapeutics. Synapticure’s innovative mbOrg platform answers this need by providing a highly reproducible approach for creating 3D mbOrgs that accurately reflect disease states relevant to ALS and FTD, including matched pathological features not seen in existing models. The platform uses an engineering-like approach, where cellular components are generated and differentiated separately and then assembled into organoids that meet the needs of a specific disease model. Synapticure has the ability to form mbOrgs from mature human astrocytes (iA) and homogeneous cortical-like neurons (iN) in defined numbers and ratios, providing a 3D environment with mature astrocytes similar to those in the healthy human brain and recapitulating key features of ALS such as aging-related disease pathology never before reported in vitro. Synapticure and our collaborators have recently successfully incorporated iPSC-derived microglia into mbOrgs, and adding microglia is a priority for this program. Synapticure’s 3D models have been validated by assaying TDP-43 proteinopathy, which contributes to disease in ~97% of ALS and ~45% of FTD cases. This includes evaluation of TDP-43 localization and phosphorylation, as well as the mis-splicing of stathmin-2 (STMN2), a recently characterized biomarker of TDP-43 proteinopathy. Synapticure’s Phase I proof of concept project seeks to advance a 2D to 3D screening pipeline for identifying such additional compounds that rescue specific phenotypes via the following Specific Aims:1) Establish and validate a 2D screen showing TDP-43 proteinopathy and rescue, and 2) Confirm efficacy of therapeutic candidates in 3D by using the 3D mbOrgs to evaluate the ability of the therapeutic candidates to rescue TDP-43 proteinopathy that is not stress induced. Following successful completion of this project, in a future Phase II application, Synapticure will look to expand the platform to patient-derived cells and include other relevant cell types, confirming the ability to screen compounds against a broad genetic background as a first step towards personalized treatment for ALS/FTD.