SBIR-STTR Award

Development of an UNC13A antisense oligonucleotide treatment for ALS and FTD Background: In 97% of ALS cases, and roughly half of FTD cases, TAR DNA-binding protein 43 (TDP-43) is lost from the nucleus to the cytoplasm, where it forms into aggregates. A major function of TDP-43 in the nucleus is to repress cryptic exon (CE) inclusion during RNA splicing. Recent studies have shown that a CE is included in UNC13A mRNA when TDP-43 is depleted from the nucleus of neurons resulting in a loss of UNC13A protein. UNC13A single nucleotide polymorphisms (SNPs) are among the strongest hits associated with ALS and FTD in human GWAS studies. The CE is located in the same intronic region as the primary risk SNP. The risk SNP exacerbates the UNC13A CE inclusion - ALS / FTD patients with both risk alleles have more CE inclusion than patients with one risk allele, who have more CE inclusion than patients with the non-risk alleles. Similarly, risk SNP carriers have a dose-dependent reduction in survival. This additive risk strongly suggests that targeting UNC13A to suppress the CE inclusion could have a substantial therapeutic benefit. Since nearly all ALS patients have TDP-43 pathology, such a treatment would benefit them and not be limited to SNP carriers. UNC13A plays a critical role in synaptic transmission and is essential for synaptic vesicle release at most excitatory synapses and neuromuscular junctions. Among all the genes known to be dysregulated by the loss of TDP-43 from the nucleus, only UNC13A has such strong genetic validation. Altered STMN2 expression in the context of TDP-43 depletion is a hallmark of ALS / FTD, yet no link between ALS risk and STMN2 variants has been established. Thus, UNC13A targeting treatments should be prioritized for rapid advancement into clinical proof of concept studies. AcuraStem's mission is to identify targets that rescue multiple forms of ALS / FTD. Thus we have established patient-specific ALS / FTD disease models of both genetically defined and sporadic diseases. We show in these models that cortical neurons derived from an ALS patient with the risk SNP have more UNC13A CE inclusion than neurons derived from ALS patients with non-risk alleles. When we depleted TDP-43 in patient-derived neurons using short interfering RNAs (siRNA) it induced a robust inclusion of CEs and reduced normal UNC13A mRNA and protein levels across many patient lines. Antisense oligonucleotides (ASOs) are an attractive approach for genetic targets in the CNS like UNC13A with several successes, including nusinersen for spinal muscular atrophy (SMA) and tofersen, soon to be approved for SOD1-ALS. We used our proprietary ASO design platform to synthesize >125 ASOs and identified several novel ASO sequences that potently blocked CE inclusion and restored UNC13A mRNA and protein levels. AcuraStem is uniquely positioned with potent UNC13A ASO candidates that can be advanced towards the clinic for ALS and FTD. Objectives & Impact: This Direct to Phase 2 project aims to optimize these candidates and identify a bona fide development candidate for advancement in investigational new drug (IND)-enabling toxicity studies. This project involves collaborating with the Jackson Laboratory to characterize a new human UNC13A TDP-43 ALS / FTD mouse model that will be essential for the field. This project has a high probability of commercial success because there is a dearth of disease-modifying treatments in development that could work for the sporadic ALS and FTD population, a large unmet need and commercial opportunity.

Public Health Relevance Statement:
Development of an UNC13A antisense oligonucleotide treatment for ALS and FTD Project Narrative Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are complex diseases that result from many diverse causes. While there are currently no drugs that slow the progression of ALS or FTD, most of the new promising therapeutic strategies are focused narrowly on modifying the specific genetic mutations known to cause disease, however these treatments won't work for the vast majority (>80% in ALS) of patients for whom the genetic cause of their disease is not known. Therefore, AcuraStem's focus has been to develop treatments that can work for all ALS and FTD patients, including those for whom the genetic factors driving their disease have yet to be discovered - a large population with urgent unmet need.

Project Terms:
anti-sense oligo; antisense oligo; Clinical; Phase; Variation; Variant; Link; Evaluation; Collaborations; TAR DNA-binding protein 43; TDP-43; TDP43; protein TDP43; protein TDP-43; Therapeutic; Genetic; Frontotemporal Dementia; Frontal Temporal Dementia; front temporal dementia; frontal lobe dementia; frontotemporal lobar dementia; frontotemporal lobe degeneration associated with dementia; Complex; Clinic; success; Toxic effect; Toxicities; superoxide dismutase 1; SOD-1; SOD-1 protein; SOD1; SOD1 gene; SOD1 gene product; novel; Disease model; disorder model; Positioning Attribute; Position; Single Nucleotide Polymorphism; Single Base Polymorphism; single nucleotide variant; Modeling; Short interfering RNA; siRNA; Small Interfering RNA; Dose; DNA Sequence Alteration; DNA Alteration; DNA mutation; Genetic mutation; Sequence Alteration; genomic alteration; The Jackson Laboratory; in vivo; Excitatory Synapse; Validation; validations; Development; developmental; GWA study; GWAS; genome wide association; genome wide association scan; genome wide association studies; genomewide association scan; genomewide association studies; genomewide association study; whole genome association analysis; whole genome association studies; whole genome association study; genome wide association study; designing; design; Population; Amyotrophic lateral sclerosis and frontotemporal degeneration; Amyotrophic lateral sclerosis and frontotemporal dementia; FTD/ALS; FTLD/ALS; Frontotemporal Lobar Degeneration/Amyotrophic lateral sclerosis; amyotrophic lateral sclerosis with frontotemporal dementia; amyotrophic lateral sclerosis/FTLD; amyotrophic lateral sclerosis/frontotemporal dementia; amyotrophic lateral sclerosis/ftd; frontotemporal dementia-amyotrophic lateral sclerosis; frontotemporal lobar dementia amyotrophic lateral sclerosis; murine model; mouse model; Risk-associated variant; risk allele; risk gene; risk genotype; risk loci; risk locus; risk variant; genetic strategy; genetic approach; vesicle release; vesicular release; knockin; Knock-in; Amyotrophic Lateral Sclerosis patients; ALS patients; sALS; sporadic ALS; sporadic amyotrophic lateral sclerosis; ALS therapy; ALS treatment; amyotrophic lateral sclerosis treatment; amyotrophic lateral sclerosis therapy; 21+ years old; Adult Human; adulthood; Adult; Allelomorphs; Alleles; Amyotrophic Lateral Sclerosis Motor Neuron Disease; Gehrig's Disease; Lou Gehrig Disease; Amyotrophic Lateral Sclerosis; Automobile Driving; driving; Cell Nucleus; Nucleus; Cytoplasm; Disease; Disorder; Pharmaceutical Preparations; Drugs; Medication; Pharmaceutic Preparations; drug/agent; Investigational Drugs; Investigational New Drugs; Exons; Genes; Government; Human; Modern Man; In Vitro; Mission; Spinal Muscular Atrophy; Aran-Duchenne disease; Cruveilhier disease; Persons; Synaptic Transmission; Neural Transmission; Neuromuscular Junction; Myoneural Junction; Neurons; Nerve Cells; Nerve Unit; Neural Cell; Neurocyte; neuronal; Pathology; Patients; Play; Probability; Proteins; Rattus; Common Rat Strains; Rat; Rats Mammals; Repression; Risk; RNA Splicing; Splicing; Messenger RNA; mRNA; Role; social role; Safety; Synaptic Vesicles; Work; Antisense Oligonucleotides; Anti-Sense Oligonucleotides; Antisense Agent; anti-sense agent