Neurodegenerative Diseases

Alzheimer’s Disease

FAST FACTS

Over 6.2 million Americans, age 65 and older are living with Alzheimer's dementia today

APOE4 is the strongest and most reproducible genetic risk factor for late-onset Alzheimer’s disease (LOAD)

Of the people diagnosed with Alzheimer’s:

%

have 1 copy of the APOE-e4 gene

%

have 2 copies of the APOE-e4 gene

AD patients with APOE4:

Accelerated onset of dementia

Worse memory performance

Overview

Alzheimer’s disease (AD) is the sixth leading cause of death in the US and the most common cause of dementia in aging. With a rapidly growing aging population, the number of AD cases is growing fast and is projected to rise drastically over the next three decades. In the U.S. alone more than 6.2 million are living with AD, a number projected to reach 14 million cases by 2050. Sadly, these trends will worsen because there are no therapies to halt or prevent AD, resulting in a substantial healthcare burden and devastating toll on patients and their families. Unfortunately, the history of drug development for AD is discouraging, with numerous failures.
AD is a complicated disease with numerous etiologies including the formation of beta amyloid plaques, tau tangles and inflammation. Most attempts at drug design have focused on single targets. However, therapies designed against this single target have proven widely ineffective and research indicates that early intervention is key. New therapeutics like Aducanumab show promise in their ability to target beta-amyloid, however, whether they can stave off the established disease or dementia, is unknown. For now, there is neither no cure nor a disease-modifying therapeutic (DMT) for AD. Thus, AD remains an unmet medical need requiring the urgent need for a paradigm shift in AD drug discovery research.

Late Onset AD (LOAD)

Late onset AD (LOAD) is a complex disease and the variability in the genetic risk and molecular profiles amongst AD patients presents significant challenges for drug development. Advancement in LOAD therapy will require the development and validation of new drug targets, including those tailored to sub-group/s of patients with specific risk factors. As such, the focus has shifted to new potential culprits, including gene-targets of LOAD. Consistently, APOE has emerged as a target for LOAD treatment.

APOE as a target

A major risk determinant of LOAD is the apolipoprotein E (APOE) gene, There are three primary allelic variants, e2, e3, and e4. APOEe2 is associated with lower disease risk, while the APOEe4 allele is the strongest and most reproducible known genetic risk factors for LOAD. Carrying one APOEe4 allele increases the risk of LOAD 3-4-fold and carrying two increases risk 9-15-fold. Further, AD individuals carrying APOEe4 have an earlier onset of dementia and worse memory performance.

Lifetime risk of Alzheimer’s Disease based on number of APOE4 copies

  • Zero: ~9% (ApoE3/3, ApoE2/3 Genotype)
  • One: ~30% (ApoE3/4, ApoE2/4 Genotype)
  • Two: ~50-90% (ApoE4/4 Genotype)

Yang, et al 2021

The popular 23andme genetic testing company reports that the APOEe4 AD risk test is the most sought-after report by consumers pursuing their own genetic testing.

Given the role APOEe4 plays in numerous AD-related pathways (tau, amyloid plaques, neuroinflammation), APOEe4 has emerged as a promising AD drug target 

ApoE4

APOE4 impacts key drivers of AD pathogenesis

Increase Abeta aggregation

Decrease lipid/cholesterol transport and clearance

Decrease cellular function

Decrease Abeta clearance

Increase inflammatory response

Decrease Insulin and VEGF signaling

Increase tau phosphorylation and tau tangle formation

Decrease glucose and mitochondrial metabolism

Decrease synaptic and neuronal function

CLRI-002

CLRI-002 is designed to lower the expression of APOE4 without the side effects of turning off APOE4 completely. The resulting impact is a reduction of amyloid and tau pathology and a decrease in neuroinflammation

Wang, et al 2019

While several groups are developing drugs to eliminate APOEe4 (via knockdown or clearance), other small studies demonstrate that complete elimination of APOEe4 may be detrimental, supporting the evolutionary maintenance of this gene. Therefore, a modern and precise LOAD therapeutic should take into consideration carrier status and strive to lower APOE4 to prevent the downstream pathogenic effects.

CLAIRIgene has developed epigenome editing tools to downregulate APOEe4 expression precisely and in allele-specific manner. Using the developed platform highlighted below, we were able to effectively and specifically modulate APOE expression by targeted modification of the epigenome landscape within APOE locus. Our gene-delivery system is based on the optimized and improved, proprietary  Adeno-Associated Viral (AAV) vector. Our epigenome therapy strategy for fine-tuning of APOE expression based on dCas9 technology is translational toward the development of a therapeutics approach to prevent and/or delay LOAD onset.

Citation: https://www.biorxiv.org/content/10.1101/2023.04.14.536951v1

Publication is currently under revision in Nature Communication

Parkinson’s Disease

FAST FACTS

Nearly 90,000 people in the U.S. are diagnosed with Parkinson’s Disease

Nearly one million people in the U.S. are living with Parkinson's disease (PD)

%

percent of Parkinson's cases to a direct genetic cause

Parkinson’s disease (PD) is the second most common neurodegenerative disorder in the world, nevertheless, currently there is no effective treatment to prevent PD or to halt its progression. The SNCA gene has been implicated as a highly significant genetic risk factor for PD. In addition, accumulating evidence has suggested that elevated levels of wild-type a-synuclein are causative in the pathogenesis of PD. To date, a-synuclein, encoded by the SNCA gene, is one of the most validated and promising therapeutic targets for PD. Moreover, manipulations of SNCA levels have demonstrated a beneficial impact. However, neurotoxicity associated with robust reduction of SNCA levels was reported in studies that utilized RNAi tools to target directly SNCA transcripts. To better control levels of SNCA, our founders, Drs. Chiba-Falek and Kantor created a system to tightly regulate the expression of SNCA transcription.

Tagliafierro et al, 2016

CLAIRIgene’s Approach

Elevated levels of SNCA have been implicated in the pathogenesis of Parkinson’s disease (PD), while normal physiological levels of SNCA are needed to maintain neuronal function. We developed new therapeutic strategies targeting the regulation of SNCA expression. To achieve that, we targeted DNA methylation at SNCA intron 1. DNA methylation at SNCA intron 1 is an attractive target for fine-tuned downregulation of SNCA levels, as it regulates SNCA transcription, and PD brains showed differential methylation levels compared to controls. To target DNA methylation in intron 1 of SNCA, we developed a system, comprising an all-in-one lentiviral vector, carried CRISPR/dCas9- fused with the catalytic domain of DNA-methyltransferase 3A (DNMT3A). Applying the system to human induced pluripotent stem cell (hiPSC)-derived dopaminergic neurons from a PD patient with the SNCA triplication resulted in fine downregulation of SNCA mRNA and protein mediated by targeted DNA methylation at intron 1. Furthermore, the reduction in SNCA levels by the guide RNA (gRNA)-dCas9-DMNT3A system rescued disease-related cellular phenotype characteristics of the SNCA triplication hiPSC-derived dopaminergic neurons, e.g., mitochondrial ROS production and cellular viability. Thus first-generation system using LV (licensed to Seelos Therapeutics) has been most recently evolved into second and third generation platform utilized AAV vector as the delivery vehicle.

In our new program (CLRI-005) we demonstrated the high potential of this target sequence combined with the AAV-CRISPR/dCas9 technology as a novel epigenetic-based therapeutic approach for PD. This is available for licensing

Kantor B, et al. (2018) Downregulation of SNCA Expression by Targeted Editing of DNA Methylation: A Potential Strategy for Precision Therapy in PD. Molecular Therapy. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6224806/

Tagliafierro L, Ilich E, Moncalvo M, Gu J, Sriskanda A, Grenier C, Murphy SK, Chiba-Falek O, Kantor B. Lentiviral Vector Platform for the Efficient Delivery of Epigenome-editing Tools into Human Induced Pluripotent Stem Cell-derived Disease Models. J Vis Exp. 2019 Mar 29;(145):10.3791/59241. doi: 10.3791/59241. PMID: 30985756; PMCID: PMC7144461. https://pubmed.ncbi.nlm.nih.gov/30985756/

Tagliafierro L, Chiba-Falek O. Up-regulation of SNCA gene expression: implications to synucleinopathies. Neurogenetics. 2016 Jul;17(3):145-57. doi: 10.1007/s10048-016-0478-0. Epub 2016 Mar 7. PMID: 26948950; PMCID: PMC4907864. https://pubmed.ncbi.nlm.nih.gov/26948950/

Lewy Body Dementia

FAST FACTS

Dementia with Lewy bodies is estimated to affect 1.4 million people in the United States.

Mutations in genes known as SNCA can cause dementia with Lewy bodies

%

It accounts for about 5 percent of all dementia cases in older individuals and is the second most common dementia after Alzheimer disease.

Lewy body dementia (LBD) is a progressive brain disorder that affects thinking, movement, behavior, and mood. It is caused by the buildup of abnormal protein deposits called Lewy bodies in the brain.

LBD is not the same as Parkinson’s, but the two are closely related: LBD causes some or all of the motor symptoms of Parkinson’s. More than 1 million people in the U.S. are affected by Lewy body dementia, according to the Lewy Body Dementia Association.  There are two main types of LBD: dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD). DLB and PDD are very similar, but the symptoms appear in a different order depending on which type of LBD a person has.

In DLB, dementia symptoms (such as memory loss, confusion, and difficulty thinking) usually appear first. Motor symptoms (such as tremors, stiffness, and slowness of movement) may develop later.

In PDD, motor symptoms usually appear first, followed by dementia symptoms.

Other symptoms of LBD can include:

  • Visual hallucinations
  • Sleep disturbances
  • Falls
  • Depression
  • Anxiety
  • Difficulty swallowing
  • Constipation
  • Urinary incontinence

There is no cure for LBD…we hope to change that

Patient and Caregiver Resources:

To learn more about Alzheimer’s Disease, visit

 

To learn more about Parkinson’s Disease, visit

 

To learn more about Lewy Body Dementia, visit https://www.lbda.org/