Slide 1: Prime Editing enables precise single amino acid substitutions to shield CD34+ HSCs
Prime Editing enables precise and efficient single amino acid substitutions to shield CD34+ hematopoietic stem cells from anti-CD117 antibody-based conditioning
Slide 2: Prime Editing is programmable for both search and replace
Prime Editing is programmable for both search and replace Prime Editing can directly write new genetic information into a targeted DNA site without requiring a DSB Gene with mutation GENE SEARCH FIND & NICK PRIME REPLACE CORRECTED Prime editor complex Prime editor complex Nicked DNA strand Prime edi
Slide 3: Preparative 'Conditioning' in HSCT is required to create space for engraftment
Preparative ‘Conditioning’ in HSCT is required to create space for engraftment of transplanted CD34+ cells Myeloid Conditioning is required for successful Non-selective Conditioning engraftment of incoming CD34+cells has unintended toxicity to patients •Clearance of bone marrow niche space Chemother
Slide 4: Cimeio CD117 antibody (CIM056) for reduced toxicity of conditioning and cell shielding of HSC
Cimeio CD117 antibody (CIM056) for reduced toxicity of conditioning and cell shielding of HSC CD117 is a receptor that is critical for the survival and proliferation of hematopoietic stem cells (HSC) Prime Editor designed to precisely install Cimeio CD117 antibody engineered to deplete CD117 shieldi
Slide 5: Research and Development workstream for shielding Prime Editors in CD34+ cells ex vivo
Research and Development workstream for shielding Prime Editors in CD34+ cells ex vivo Assessment of cell health, function, editing efficiency, & cell shielding Evaluate cell Deliver PE Cryopreserve Evaluate Thaw CD34+ cells potency (CFC) & targeting KIT & thaw Prime Editing shielding mRNA pegRNA ng
Slide 6: Prime Editor shields CD34+ cells from CD117 Ab with no impact on viability or potency ex vivo
Prime Editor shields CD34+ cells from CD117 Ab with no impact on cell viability or potency ex vivo PE does not impact CD117 Ab depletes unedited cells, PE CD117 Ab enriches PE cells with cell viability cell potency maintained biallelic edits E GM GEMM % CFCs With Prime Edit 100 100 100 1 Allele per
Slide 7: Clinical scale production of >70% Prime Edited CD34+ cells
Clinical scale production of >70% Prime Edited CD34+ cells with no impact on cell viability or multipotency Half of PE CD34+ cell clones have biallelic shielding edit at KIT (CD117) gene 73% of CD34+ cell clones carry Prime Clinical Scale Process PE CD34+ cell potency maintained Edit; 50% of which h
Slide 8: Prime Edited HSPC are shielded from CD117 Ab mediated depletion in vivo
Prime Edited hematopoietic stem progenitor cells (HSPC) are shielded from CD117 Ab mediated depletion in vivo Cell infusion Bone marrow (BM) collection Nonclinical Study Endpoints ✓ Prime Editing in HSC PE or EP control ✓ Engraftment 16 weeks CD34+ cells ✓ Multilineage reconstitution NBSGW Antibody
Slide 9: In vivo shielding boosts PE CD34+ cells in bone marrow with biallelic edits
In vivo shielding boosts PE CD34+ cells in bone marrow to 100% with 80% of cells carrying biallelic edits % of CD34+ cell clones with biallelic edit increases to 80% after CD117 Ab Tx Comparable Bone Marrow Shielded HSCs are enriched and 100% of BM engrafted HSC carry reconstitution in both antibody
Slide 10: No unintended edits, off-target editing, or chromosomal rearrangements detected
No unintended edits, off-target editing, or chromosomal rearrangements detected in PE CD34+ cells Three orthogonal methods used to determine presence of Off Target Editing No detectable off-Target edits No Chromosomal Rearrangements Detectable Positive Control Test Article Shielding gRNAs + RNF2 + s
Slide 11: Optimized PEv2 Prime Editor increases PE efficiency to 100%
Optimized PEv2 Prime Editor increases PE efficiency to 100% with 80% of cells carrying biallelic shielding edits without CD117 Ab treatment 1 Allele 2 Alleles % CFC with Shielding edit 100 80 60 40 20 0 PEv1 PEv2 *PEv1 shown in preceding studies PEv1 = Prime Editor version 1; PEv2 = Prime Editor ver
Slide 12: ~80% biallelic Multiplex Prime Editing efficiency
~80% biallelic Multiplex Prime Editing efficiency with i) disease correcting Prime Editor and ii) shielding Prime Editor v2 CD117 Shielding Edit and a second Prime Edit at a clinically relevant target site after single-step electroporation 100 Respective Edit 80 Single Edit Outcomes: % CFC with Ther
Slide 13: Shielding has potential to provide physician control over HSCT outcome
Shielding has potential to provide a measure of control to physician over HSCT outcome following engraftment ILLUSTRATION: Shielding potential to increase engraftment in patients post PE CD34+ cell infusion No Shielding = No Opportunity Shielding Prime Edit + CD117 Ab = Opportunity to increase chime
Slide 14: Summary
Summary • Clinical scale production of Prime Edited CD34+ cells with a Prime Editor showed no observable impact on cell viability, or multipotency, with >70% cells carrying the shielding edit • In vivo, shielding with anti-CD117 Antibody boosts Prime Edited CD34+ cells to 100% with ~80% of cells car