Slide 1: A gene editing approach for chronic hepatitis B
A gene editing approach for chronic hepatitis B: Elimination of hepatitis B virus in vivo by targeting cccDNA and integrated viral genomes with a sequence-specific ARCUS nuclease June 22, 2023 EASL Emily B. Harrison, PhD HBV Research Lead, Gene Therapy Discovery
Slide 2: Forward-Looking Statements
Forward-Looking Statements This presentation contains forward-looking statements, as may any related presentations, within the meaning of the Private Securities Litigation Reform Act of 1995. The Company intends such forward- looking statements to be covered by the safe harbor provisions for forward
Slide 3: Disclosures
Disclosures • I am an employee of Precision BioSciences, Inc. (Nasdaq: DTIL) 3
Slide 4: Rationale for a functional cure
Rationale for a functional cure: ARCUS gene editing inactivates cccDNA and integrated HBV to drive durable antigen loss HBV Infected Hepatocyte ARCUS LNP Chronic Hepatitis B affects inactivate ~250 million people cccDNA inactivate integrated HBV Durable Antigen Loss Functional Cure 4
Slide 5: ARCUS: Engineering Nature's Genome Editing System
ARCUS: Engineering Nature’s Genome Editing System • ARCUS is derived from I-CreI, a homing endonuclease from algae — Protein optimization results in high specificity — Sticky ends at cut site allow for: — Complex edits, such as gene insertion — Sensitive detection of off-target editing 5
Slide 6: ARCUS-POL recognizes a highly conserved sequence in HBV-POL gene
ARCUS-POL recognizes a highly conserved sequence in HBV-POL gene Target site conserved in 92% of isolates Targeted region is present in the across serotypes1,2 majority of integrations3 1. Gorsuch CL, et al. Mol Ther. 2022;30(suppl 9):2909-2922. 2. Image source adapted from: Tu T, et al. Viruses. 20
Slide 7: ARCUS-POL gene editing inactivates cccDNA and integrated HBV
ARCUS-POL gene editing inactivates cccDNA and integrated HBV to drive durable antigen loss Outcomes DNA HBsAg Degradation by Loss of Transcript and exonuclease cccDNA protein loss 1 HBV cccDNA DNA break HBV cccDNA occurs “Indel” via DNA Transcript and repair Edited cccDNA protein loss Edited Transcr
Slide 8: ARCUS-POL inactivates cccDNA in HBV-infected primary human hepatocytes
ARCUS-POL inactivates cccDNA in HBV-infected primary human hepatocytes 85% 30% degradation by remaining cccDNA exonuclease HBV has indels cccDNA 89.5% total cccDNA engagement ARCUS LNP 30% 150 ARCUS 30 (cccDNA/non-targeting) LNP % To Control 100 20 % Indels Non-targeting nuclease ARCUS-POL 50 10 14%
Slide 9: ARCUS-POL reduces extracellular HBV DNA and HBsAg in hepatocytes
ARCUS-POL reduces extracellular HBV DNA and HBsAg in primary human hepatocytes 80% reduction in 77% reduction in No change in extracellular HBV DNA extracellular HBsAg extracellular albumin 150 150 250 Non-targeting nuclease HBV DNA (% of control) Albumin (% of control) ARCUS-POL HBsAg (% of control
Slide 10: ARCUS-POL inactivates integrated HBV DNA and decreases HBsAg
ARCUS-POL inactivates integrated HBV DNA and decreases HBsAg in liver cells with integrated HBV DNA 80% indels in integrated HBV 80% decrease in HBsAg Gorsuch et al, 2022. Molecular Therapy 10
Slide 11: Optimization of ARCUS-POL increases activity and specificity
Optimization of ARCUS-POL increases activity and specificity in liver cells with integrated HBV DNA Optimization Optimization increases activity increases specificity Off-target sites Target site Gorsuch et al, 2022. Molecular Therapy 11
Slide 12: Measuring HBV DNA integration into the genome of hepatocytes
Measuring HBV DNA integration into the genome of HBV infected primary human hepatocytes isolate and sequence junctions HBV HBV integrates fragment DNA Chromosomes Chromosomes with Chromosome Fragments Integrated HBV 12
Slide 13: Optimization reduces integrations and translocations from gene editing
Optimization of ARCUS-POL reduces integrations and translocations resulting from gene editing Mock (HBV only) ARCUS Cut Site known off- target site? Early-Generation ARCUS Treated Optimized ARCUS Treated Gorsuch et al, 2022. Molecular Therapy 13
Slide 14: HBV Episomal In Vivo Model
HBV Episomal In Vivo Model AAV-HBsAg ARCUS-POL Liver Injection LNP Injection Necropsy 5e11 vg 2 mg/kg Readouts: • Inactivation of AAV-HBsAg (cccDNA surrogate) • HBsAg loss in serum and liver 14
Slide 15: ARCUS-POL inactivates viral DNA and reduces HBsAg in mouse model
ARCUS-POL inactivates viral DNA and durably reduces HBsAg in an episomal mouse model AAV- HBsAg 40% reduction in 86% indels in AAV copy number remaining AAV 96% reduction in >90% total viral DNA engagement secreted HBsAg 10 100 ARCUS-POL ✱ Administration AAV Copies/Diploid Cell 40000 PBS 8 80 ARCUS-
Slide 16: Rationale for a functional cure
Rationale for a functional cure: ARCUS gene editing inactivates cccDNA and integrated HBV to drive durable antigen loss HBV Infected Hepatocyte ARCUS LNP inactivate cccDNA inactivate integrated HBV Durable Antigen Loss Functional Cure 16
Slide 17: Acknowledgements
Acknowledgements Precision BioSciences, Inc. • Cassie Gorsuch • Greg Falls • Amod Joshi • Paige Nemec • Jason Holt • Tyler Goodwin • Amy Rhoden Smith • Wendy Shoop • Rob Brown • Jeff Smith • Emma Sevigny • Neil Leatherbury • Janel Lape • Forrest Karriker • Derek Jantz Gilead Sciences • Mei Yu • Dong
Slide 18: Dedicated To Improving Life
Overcome cancer. Cure genetic disease. Dedicated To Improving Life