New Preclinical Data Presented at the 2021 American Society of Genetic & Cell Therapy Annual Meeting Highlights Precision BioSciences’ ARCUS In Vivo Genome Editing

Results Show Promising Gene Editing Approach for Transthyretin Amyloidosis

Precision BioSciences, Inc. (Nasdaq: DTIL), a clinical stage biotechnology company developing allogeneic CAR T and in vivo gene correction therapies with its ARCUS^® genome editing platform, announced new in vivo data resulting from a preclinical research collaboration with investigators at the University of Pennsylvania presented today at the 2021 American Society of Genetic & Cell Therapy (ASGCT) Annual Meeting.

In the poster, “Translation of an AAV-delivered gene editing approach for transthyretin amyloidosis from mice to nonhuman primates,” researchers report positive preclinical results using ARCUS to knock out the transthyretin (TTR) gene responsible for transthyretin amyloidosis (ATTR), a rare disease that leads to peripheral neuropathy and/or cardiomyopathy.

“While there are approved treatment approaches for ATTR, these require repeated administration, whereas a gene editing approach delivered by adeno-associated viral vectors, including the one we’re studying with the ARCUS nucleus, could provide an effective one-time treatment option,” said Jenny Greig, Ph.D., Senior Director, Gene Therapy Program, Perelman School of Medicine, University of Pennsylvania. “The significant reduction in serum TTR levels following genomic editing of the TTR gene indicates that AAV delivery of TTR-specific ARCUS nucleases could represent an effective treatment for ATTR.”

In ARCUS-treated NHPs, high levels of genomic editing were achieved, resulting in substantial and persistent serum TTR reductions. Up to 46% indels were found at the genomic DNA locus, translating to ~80% editing of the TTR messenger RNA transcripts, which was maintained between liver biopsies collected at 18 and 128 days post-AAV administration. Researchers found that high editing efficacy of the TTR gene was reflected in serum TTR levels, where there was an associated reduction of greater than 95% by day 21 post-vector administration in three out of the four ARCUS-treated NHPs. These serum TTR reductions endured to 250 days after a single AAV administration, suggesting the genomic edits and subsequent protein reduction may be permanent.

“Using ARCUS to knock out the TTR gene in NHPs provided an important opportunity to evaluate the persistent effects of ARCUS for in vivo editing,” said Derek Jantz, Ph.D., Chief Scientific Officer and co-founder of Precision BioSciences. “We’re excited about the growing body of data demonstrating this ‘one and done’ approach with ARCUS, and what it may mean for transforming the treatment of rare genetic diseases in humans.”

All abstracts for the ASGCT 2021 Meeting are available on the meeting website.

About ARCUS

ARCUS^® is a proprietary genome editing technology discovered and developed by scientists at Precision BioSciences. It uses sequence-specific DNA-cutting enzymes, or nucleases, that are designed to either insert (knock-in), remove (knock-out), or repair DNA of living cells and organisms. ARCUS is based on a naturally occurring genome editing enzyme, I-CreI that evolved in the algae Chlamydomonas reinhardtii to make highly specific cuts in cellular DNA. Precision's platform and products are protected by a comprehensive portfolio including more than 75 patents to date.

About Precision BioSciences, Inc.

Precision BioSciences, Inc. is a clinical stage biotechnology company dedicated to improving life (DTIL) with its wholly proprietary ARCUS^® genome editing platform. ARCUS is a highly specific and versatile genome editing platform that was designed with therapeutic safety, delivery, and control in mind. Using ARCUS, the Company’s pipeline consists of multiple “off-the-shelf” CAR T immunotherapy clinical candidates and several in vivo gene correction therapy candidates to cure genetic and infectious diseases where no adequate treatments exist. For more information about Precision BioSciences, please visit www.precisionbiosciences.com.

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