Gene Therapy Trial for ApoE4 Homozygotes

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Re: Gene Therapy Trial for ApoE4 Homozygotes

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grommet wrote:
ApropoE4 wrote: To add to NF52's great summary - the trial hasn't shown success in 40% of participants - rather it's shown APOE4 expression was down by 40% on average among participants, while APOE2 expression was maintained at least over the months that have passed.
This is a fascinating thread…

Does anyone know how APOE4 **expression** is measured? Is the test available to people (me) who want to pay for it?
What a great question! Here's an excerpt from the Discussion section of a 2020 article that seems to offer an explanation--although my level of reading comprehension of this stuff is woeful! The donated brains they studied were from people with Alzheimer's ["AD"] and those with no dementia [controls]
APOE is the strongest known genetic risk factor for late-onset AD. From a genetics perspective, a gene strongly associated with a disease traditionally plays a direct role in the pathogenesis of that disease. Such an effect is usually carried out by the gene’s products including RNA and protein and can be explained by a change in either their qualities (structure or function) or quantity (expression levels) that leads to physiological changes....Like the full-length APOE mRNA, APOE circRNAs are expressed at higher levels in AD frontal lobe compared to control frontal lobe...These results suggest that APOE circRNAs may indeed play a role in AD risk. It is also interesting to note that they carry the ε4 versus ε2/ε3 variants, implying the potential for ε4-linked effects in AD. Whether these APOE circRNAs have an independent biological effect in AD warrants further investigation... APOE circRNAs could potentially be developed as a new biomarker for AD to monitor disease progression and/or intervention.
Redefining transcriptional regulation of the APOE gene and its association with Alzheimer’s disease
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Julie G
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Re: Gene Therapy Trial for ApoE4 Homozygotes

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To add to NF52's great summary - the trial hasn't shown success in 40% of participants - rather it's shown APOE4 expression was down by 40% on average among participants, while APOE2 expression was maintained at least over the months that have passed.
What is the source for this information? Might be in this thread but I can't seem to find it (?)
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Re: Gene Therapy Trial for ApoE4 Homozygotes

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Hey Julie. I was wondering the same thing.

It might be from a talk the Cornell team gave at a conference recently. I didn't attend (I wish I had!), but the abstract is below. Note: the talk was mostly about a different, newer therapy, but it's likely that they talked about the therapy ("first generation") currently being trialed, as background to the discussion of the newer therapy.

Apologies for not giving the URL to the source of the abstract, but I forgot to note it, and now I can't "google up" the abstract page. Arg!

339. Second Generation APOE2+APOE4‾
AAV-Mediated Gene Therapy for APOE
Homozygotes at Risk for Alzheimer’s Disease
Rachel Montel, Esther Frenk, Ronald G. Crystal, Katie
M. Stiles
Genetic Medicine, Weill Cornell Medical College, New York, NY

Alzheimer’s disease (AD) is a progressive degenerative neurological disorder associated with a strong genetic risk in polymorphisms of the apolipoprotein E (APOE) allele. Inheritance patterns of APOE alleles demonstrate that APOE4/4 homozygotes have a 14.5-fold increased risk of developing AD, while APOE2/2 homozygotes are protected against developing AD. The knowledge that the presence of APOE2 in APOE2/4 heterozygotes markedly reduces the APOE4 risk led to the development of a 1st generation preventative AD gene therapy delivering APOE2 to the brain of APOE4 homozygotes. In the present study, we hypothesized that a 2nd generation gene therapy using an adeno-associated virus (AAV) expressing therapeutic APOE2 with artificial microRNAs (miRNA) targeting endogenous APOE4 may further mitigate the risk and limit AD development of APOE4 homozygotes. To test this hypothesis, we evaluated silencing of APOE4 expression using a series of siRNAs targeting APOE4 in the U-87 human glioblastoma cell line. Of these siRNAs, one sequence (siRNA2) significantly silenced APOE expression and was selected for generating novel APOE-targeting miRNAs that were incorporated into an artificial miRNA cassette for expression in the AAV vector. These miRNAs were cloned into the intron in the CAG promoter 5’ of the transgene or in the 3’ untranslated region (UTR) of the pAAV expression cassette. To determine the efficiency of silencing by the miRNAs, the APOE4 target site was cloned into the pmirGLO-luciferase plasmid and cotransfected into 293T cells with pAAV expression plasmids containing APOE-targeting miRNAs. There was a >40% reduction in luciferase activity (representing APOE4 expression) in the presence of APOEtargeting miRNA compared to the control scrambled miRNA. In parallel, an APOE2 expression cassette was designed that was resistant to silencing by the miRNAs. To test expression of the modified APOE2 cDNA, 293T cells were transfected, followed by analysis of APOE2 expression by quantitative PCR and Western analysis. The mRNA and protein expression levels from the miRNA resistant APOE2 cDNA were similar to unmodified APOE2. These observations demonstrate that APOE4 can be targeted for silencing by miRNA incorporation into an AAV expression cassette with a therapeutic APOE2 as a 2nd generation gene therapy for the APOE2+APOE4- treatment of APOE4 homozygous individuals at high risk for the development of Alzheimer’s disease.
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Re: Gene Therapy Trial for ApoE4 Homozygotes

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Julie G wrote:
To add to NF52's great summary - the trial hasn't shown success in 40% of participants - rather it's shown APOE4 expression was down by 40% on average among participants, while APOE2 expression was maintained at least over the months that have passed.
What is the source for this information? Might be in this thread but I can't seem to find it (?)
The source was a post by ApropoE4 on April 29 in this thread. They didn’t link to the original source.
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Re: Gene Therapy Trial for ApoE4 Homozygotes

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By source I meant "original source". So much time has gone by it would probably be worth it to see what new data there is. I'll try to find out.
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Re: Gene Therapy Trial for ApoE4 Homozygotes

Post by Julie G »

Hey Julie. I was wondering the same thing.
The source was a post by ApropoE4 on April 29 in this thread. They didn’t link to the original source.
Thank you both. Yes, I would still like to see the original source and can't find it. From a quick skim (as a layperson) this doesn't appear to be a progress report on the trial but rather the in vitro rationale for the hypothesis. The fact that they've now got funding suggests that they're having some success (?) but I'd appreciate more information.
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Re: Gene Therapy Trial for ApoE4 Homozygotes

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Hey Julie. The abstract is about a different gene therapy product (LX1020), but my assumption is that the therapy in the ongoing trial, LX1001/AAVrh.10hAPOE2, would have very likely been discussed in that talk, as background.

See:

https://www.lexeotx.com/pipeline

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Re: Gene Therapy Trial for ApoE4 Homozygotes

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