# Nuclease free gene editing approaches to treat alpha-1 antitrypsin disease

> **NIH NIH R01** · UNIV OF MASSACHUSETTS MED SCH WORCESTER · 2022 · $376,875

## Abstract

Alpha-1 antitrypsin deficiency (AATD) is a common genetic disorder that can lead to both liver and lung
disease and currently affects an estimated 3.4 million patients worldwide. Alpha-1 antitrypsin (AAT) is encoded
by SERPINA1 and is primarily secreted by hepatocytes making it the most abundant serum antiprotease. One
of the most common disease variants in AATD is a mutation resulting in a glutamate to lysine (Glu342Lys)
substitution known as the PiZ allele or Z-AAT. In contrast to the normal PiM allele (M-AAT), the Z-AAT protein
is prone to polymerization and consequently is either directed for proteolysis or aggregates in the endoplasmic
reticulum of hepatocytes. With up to 85% of the AAT protein being retained as polymers or degraded in the
liver, it sets the stage for both the loss-of-function (lung) and toxic gain-of-function (liver) diseases observed in
AATD patients. Normally AAT is secreted and diffuses throughout the bodily organs where it protects tissue
from the `unchecked' or `off-target' activity of proteases. In the lungs, the loss-of-function phenotype is due to
the imbalance of protease/antiprotease homeostasis. Specifically, the protease known as neutrophil elastase,
which is secreted by neutrophils as a form of innate immunity, goes unchecked and over years leads to the
degradation of the lung architecture. This eventually manifests as chronic obstructive pulmonary disease
(COPD) and emphysema. In contrast, Z-AAT aggregation and polymerization causes liver disease by a toxic
gain-of-function mechanism due to accumulation of misfolded protein in the hepatocytes whereby 10-20% of
PiZ homozygote patients suffer from clinical liver disease ranging from fulminant liver failure and cirrhosis to
hepatocellular carcinoma. Our group has developed strategies for simultaneous gene augmentation with
mutant gene reduction for both lung and liver disease with dual function vectors, but an unmet need remains.
We need to address liver disease in a young, actively dividing liver as is the case of AATD liver disease in the
pediatric population. Furthermore, gene editing approaches may offer longer-term solutions over episomal AAV
gene therapy for adult livers that are slowly turning over due to disease.
 There are two notable advancements that will support the development of this second generation of
rAAV-based therapies for liver disease. The first of these advances is that we now appreciate that homologous
recombination (HR) with AAV can be achieved at high enough efficiency without the use of nuclease to have a
meaningful clinical impact for liver disorders. The second important development in the AAV-mediated gene
editing field is the realization that certain AAV serotypes are better at achieving nuclease-free homologous
recombination. Recently new AAV members of clade f known as AAV-HSCs were isolated form hematopoietic
stem cells, and these vectors have shown high HR activity. Thus, this grant aims to develop novel nuclease-
free gene-edit...

## Key facts

- **NIH application ID:** 10312772
- **Project number:** 5R01DK098252-08
- **Recipient organization:** UNIV OF MASSACHUSETTS MED SCH WORCESTER
- **Principal Investigator:** Terence R. Flotte
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $376,875
- **Award type:** 5
- **Project period:** 2013-05-27 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10312772

## Citation

> US National Institutes of Health, RePORTER application 10312772, Nuclease free gene editing approaches to treat alpha-1 antitrypsin disease (5R01DK098252-08). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10312772. Licensed CC0.

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