Exhibit 99.1 Analyst & Investor Research Webcast September 28, 2021 1

Forward-looking statements This document contains forward-looking statements. All statements other than statements of historical facts contained in this document, including statements regarding possible or assumed future results of operations, preclinical and clinical studies, business strategies, research and development plans, collaborations and partnerships, regulatory activities and timing thereof, competitive position, potential growth opportunities, use of proceeds and the effects of competition are forward-looking statements. These statements involve known and unknown risks, uncertainties and other important factors that may cause the actual results, performance or achievements of Wave Life Sciences Ltd. (the “Company”) to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “aim,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions. The forward-looking statements in this presentation are only predictions. The Company has based these forward-looking statements largely on its current expectations and projections about future events and financial trends that it believes may affect the Company’s business, financial condition and results of operations. These forward-looking statements speak only as of the date of this presentation and are subject to a number of risks, uncertainties and assumptions, including those listed under Risk Factors in the Company’s Form 10-K and other filings with the SEC, some of which cannot be predicted or quantified and some of which are beyond the Company’s control. The events and circumstances reflected in the Company’s forward-looking statements may not be achieved or occur, and actual results could differ materially from those projected in the forward-looking statements. Moreover, the Company operates in a dynamic industry and economy. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties that the Company may face. Except as required by applicable law, the Company does not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise. 2

Today’s agenda PRESENTATION SPEAKER Paul Bolno, MD, MBA Opening Remarks President and CEO Chandra Vargeese, PhD Applying PRISM Principles for Rational Oligonucleotide Design Chief Technology Officer Chandra Vargeese, PhD Building a Best-in-Class ADAR Editing Capability: Introducing AIMers Chief Technology Officer Ken Rhodes, PhD Advancing ADAR Editing in the CNS SVP, Therapeutics Discovery Paloma Giangrande, PhD Restoring Functional AAT Protein with ADAR Editing: Program Update VP, Platform & Discovery Sciences Biology Q&A Paul Bolno, MD, MBA Closing Remarks President and CEO 3

Opening Remarks Paul Bolno, MD, MBA President and CEO 4

We are taking part in a genetic revolution • Greater understanding of genetic • Wave is developing therapeutics to drug drivers of disease and definition at the transcriptome to turn on, switch molecular level off, or modulate expression of faulty genes • >6,000 genetically defined diseases • Increase in genetic testing enabling identification of individuals likely to DNA benefit from treatment Many diseases beyond RNA the reach of traditional treatments Protein Sources: Shen et al, Genetics Research, 2015; Hopkins et al, Nat Rev Drug Discov, 2002; geneticdiseasefoundation.org 5

Strategic decision to intervene at RNA level RNA-targeting therapeutics offer ideal balance of precision, durability, potency, and safety Address underlying genetic Defined path to drivers of disease commercialization Durable effects to enable Simplified delivery infrequent dosing 6

Biological machinery in our cells can be harnessed to treat genetic diseases Editing Silencing Splicing • Oligonucleotide-• Leverages exon skipping • Efficient editing of RNA directed delivery of RNA machinery to restore a bases using endogenous to regulate enzymes working transcript ADAR Endogenous RNase H Endogenous AGO2 RISC Endogenous Restored Reading ADAR enzyme Frame 7

Unlocking the body’s own ability to treat genetic disease DESIGN OPTIMIZE Chemistry Unique ability to construct Provides the resolution to Sequence single isomers and control observe this structural three structural features of interplay and understand how oligonucleotides to efficiently it impacts key pharmacological engage biological machinery properties Stereochemistry Built-for-Purpose Candidates to Optimally Address Disease Biology Silencing | Splicing | RNA Editing 8

Wave is the leader in chirally-controlled rationally designed stereopure oligonucleotides Stereochemistry is a Chirality matters: affects PRISM controls reality of chemically- pharmacology of stereochemistry modified nucleic acid oligonucleotides in throughout drug discovery therapeutics vitro and in vivo and development process Current therapeutics with chiral Increasingly recognized by leaders Enables design and optimization backbone modifications: in nucleic acid therapeutics: of fully-characterized, single- isomer RNA therapeutics Antisense siRNA oligonucleotides Exon-skipping mRNA oligonucleotides therapeutics RNA guide strands Dominant IP portfolio and unique ability to manufacture and screen stereopure oligonucleotides 9 Jahns et al., NAR, 2021; Hansen, et al. 2021; Funder, Albaek et al. 2020

PRISM platform is continuously improving Design & optimize PN chemistry Stereochemistry Choose Machine modality to learning Rapidly Genetic code Predictive best address develop modeling carried by Scalable, genetic target clinical RNA to cost-effective candidates in predict manufacturing Silencing reproducible sequence Splicing way In vivo Editing models Iterative analysis of Platform in vitro and improves as in vivo learnings outcomes from each program are applied Continuous definition of design principles deployed across programs 10

Improvements in PRISM primary screen hit rates accelerate drug discovery Primary screen hit rates with silencing far above industry standard hit rates Chemistry, PN stereochemistry & machine learning optimization 100 80 80.0% (2020 - current) 60 55.4% (2019) 40 Stereopure 32.9% 20 Stereorandom 12.2% 0 Chemistry improvements and PRISM advancement All screens used iPSC-derived neurons; Data pipeline for improved standardization. Hit rate = % of oligonucleotides with target 11 knockdown greater than 50%. Each screen contains >100 oligonucleotides. ML: machine learning % Hit Rate

Data sciences enable prediction of new potential therapeutic exon-skipping targets Model trained on millions of Predicts skippable exons that Identifies clinically relevant known protein sequences are currently undiscovered genes with skippable exons Is an exon amenable Identified ~2,500 potential exon- Identified >10,000 exons that to exon-skipping skipping targets with are predicted to be skippable but oligonucleotides? oligonucleotide therapeutics as are currently unannotated compared ~100 identified skippable in literature Experimentally Exon ByPASS predicted Many predicted confirmed skippable but (PubMed) unannotated exons are validated in public data ~2500 genes ~100 genes Exon ByPASS: predicting Exon-skipping Based on Protein Amino acid SequenceS; Data presented at OTS 2021. Manuscript submitted 12

Advancing programs using multiple modalities Silencing Skipping Editing ALS and FTD DMD AATD C9orf72 (WVE-004) Exon 53 (WVE-N531) SERPINA1 Huntington’s disease mHTT SNP3 (WVE-003) Neurology Multiple undisclosed targets ALS: Amyotrophic lateral sclerosis; FTD: Frontotemporal dementia; DMD: Duchenne muscular dystrophy; AATD: Alpha-1 antitrypsin deficiency 13

Building a leading genetic medicines company • Scientific approach focused on unlocking the body’s own ability to treat genetic disease • PRISM platform enables multiple modalities for built-for-purpose therapeutics • Leading the way in rationally designed stereopure oligonucleotides with innovative backbone chemistry • Robust portfolio of PN-modified, stereopure oligonucleotides, including three programs in clinic and multiple ADAR editing discovery programs 14

Applying PRISM Principles for Rational Oligonucleotide Design Chandra Vargeese, PhD Chief Technology Officer 15

PRISM platform enables rational drug design Sequence Chemistry 5’ B B: bases R: 2’ modifications A, T, C, mC, G, U, OMe, MOE, F, 3’ 2’ other modified bases other modifications X R 5’ B Stereochemistry X: backbone chemistry 2’ PO, PS, PN3’ Chiral control of R any stereocenter 5’ modifications, backbone modifications 16

Optimization framework compatible across different modalities Interplay between key structural ..to modulate key … and apply to multiple components of oligonucleotides… aspects of activity… therapeutic modalities • Silencing Potency Tissue exposure• Splicing (exon-skipping) Duration of activity • ADAR editing 17

Innovating new backbone chemistry modifications PRISM backbone linkages PO PS PN B B B O O O O O O (Sp) (Rp) O O O R R R O O O P P P - - O S N B B B O O O O O O O O O R R R … … … … … … Phosphoryl guanidine Chirality Chirality Chirality x-ray structure None PN backbone Rp PS backbone Rp PN backbone Sp PS backbone Sp Negative Negative Neutral example charge charge charge PO: phosphodiester PS: phosphorothioate 18

Rationally placed stereopure PN modifications enhance pharmacology across modalities example … and improves key pharmacological Adding PN linkages benefits all drivers of translation PRISM modalities… • Efficient engagement • Target knockdown, Silencing Potency of RNase H or Ago2 splicing or editing • In the right tissues, • Efficient uptake in Splicing Exposure cells and cellular the cell nucleus compartments • Enabling infrequent • Efficient engagement Editing Durability administration of ADAR 19

Potency is enhanced with addition of PN modifications across modalities Silencing Splicing Editing Target knockdown (% remaining) % Skipping % Editing 100 80 60 40 20 0 -8 -6 -4 -2 0 2 10 10 10 10 10 10 Concentration (µM) Concentration (mM) Ranked by potency of reference PS/PO compound Ranked by potency of reference PS/PO compound PS/PO/PN PS/PO (Stereopure) PS/PO reference compound PS/PN modified compound PS/PO (Stereorandom) Left: Experiment was performed in iPSC-derived neurons in vitro; target mRNA levels were monitored using qPCR against a control gene (HPRT1) using a 20 linear model equivalent of the DDCt method; Middle: DMD patient-derived myoblasts treated with PS/PO or PS/PO/PN stereopure oligonucleotide under free-uptake conditions. Exon-skipping efficiency evaluated by qPCR. Right: Data from independent experiments Improved knockdown Improved skipping % Editing Improved editing

Adding PN chemistry modifications to C9orf72- targeting oligonucleotides improved potency in vivo Cortex Spinal Cord C9orf72-targeting oligonucleotides PS/PO backbone chemistry PS/PO/PN backbone chemistry Exposure (µg/g) Exposure (µg/g) Improved tissue exposure Target knockdown: Liu, TIDES poster 2021; Oligonucleotide concentrations quantified by hybridization ELISA. Graphs show robust best fit lines with 95% 21 confidence intervals (shading) for PK-PD analysis. Manuscript submitted. %C9orf72 V3 transcript remaining Improved knockdown

Adding PN chemistry modifications led to overall survival benefit in dKO model PN-containing molecules led to 100% dKO survival 100 PS/PO/PN, 150 mg/kg weekly PS/PO/PN, 75 mg/kg bi-weekly PS/PO, 150 mg/kg weekly 75 PBS 50 25 Note: Untreated, age-matched mdx mice had 100% survival at study termination [not shown] 0 0 4 8 12 16 20 24 28 32 36 40 Time (weeks) dKO; double knockout mice lack dystrophin and utrophin protein. mdx mice lack dystrophin. Left: Mice with severe disease were euthanized. dKO: 22 PS/PO/PN 150 mg/kg n= 8 (p=0.0018); PS/PO/PN 75 mg/kg n=9 (p=0.00005); PS/PO n=9 (p=0.0024), PBS n=12 Stats: Chi square analysis with pairwise comparisons to PBS using log-rank test. Manuscript submitted. Survival probability (%)

PN chemistry improves exposure and target engagement in key tissues p≤0.0001 p≤0.0001 p≤0.0001 Exon-skipping oligonucleotides PS/PO p≤0.0001 backbone chemistry p≤0.0001 PS/PO/PN p≤0.01 backbone chemistry p≤0.0001 p≤0.0001 p≤0.0001 6x weekly 75 mg/kg subcutaneous doses; Sample collected 2 days after last dose. Manuscript submitted 23

PRISM principles applied to another class of silencers: siRNA PRISM siRNA AGO2 RISC Complex 24

Application of PRISM principles to siRNA improves another class of silencers PN chemistry improves potency and durability of ESC format Potency Durability Ago2-loading mTtr mRNA (liver) mTTR protein (serum) Guide strand-Ago2 IP (liver) Dose (2 mg/kg) Dose (6 mg/kg) **** 15 125 35x 100 100 ~2-fold 75 10 75 **** ** 50 50 5x 25 5 25 -5 p < 1.0 x 10 0 0 0.6 10 20 30 40 0 2 6 0 Time (days) Dose (mg/kg) siRNA chemistry PBS ESC Ref PS/PO PN/PS/PO Ttr-targeted siRNA (Left) C57Bl/6 mice administered single 0.2, 2 or 6 mg/kg subcutaneous dose on day 1. Tissue harvested on day 8. Stats: 2-way ANOVA with post-hoc comparison to ESC. (Middle) Mice received single 6 mg/kg subcutaneous dose on day 1. Serum collected weekly. Stats: 2-way mixed ANOVA with post hoc comparisons PN vs Reference. (Right) As described for 25 left panel (2 mg/kg); Ago2 loading measured by qPCR after immunoprecipitation (IP) and normalized to miR-122; Stats: 1-way ANOVA followed by Tukey’s honest significance test. ** P<0.01, *** P<0.001****, P<0.0001. All post-hoc P values Bonferroni-corrected for multiple hypotheses. Reference: Enhanced Stabilization Chemistry ESC Ref PS/PO PN/PS/PO % Ttr mRNA remaining % Serum Ttr (relative to pre-dose) Relative Guide strand loading (Ttr/miR-122)

Application of PN chemistry to siRNA: Improving on the state-of-the-art PN chemistry extends duration of GalNAc-conjugated Advanced ESC format Enhanced duration of activity with PN Dose mTTR protein (serum) (1 mg/kg) PBS Adv ESC Ref PN/PS/PO • PN extends 50% knockdown period for GalNAc-conjugated Adv ESC 100 siRNAs 75 • Further optimization studies are in progress 50 50% increase in duration of activity 25 -12 p < 1.0 x 10 0 0 20 40 60 80 Time (days) Mice received a single 1 mg/kg subcutaneous dose on day 1. Serum was collected weekly. Stats: 2-way mixed ANOVA with post hoc comparisons PN vs 26 Reference. P value is Bonferroni corrected for multiple hypotheses. % Serum Ttr (relative to PBS)

PRISM provides visibility into effects of backbone stereochemistry within every sequence • Backbone stereochemistry impacts pharmacologic properties • PRISM enables stereochemical control to fully characterize and investigate structure activity relationship (SAR) of each therapeutic candidate • Standard in small molecule and antibody development Backbone stereochemistry can be a tool to modulate pharmacologic properties, including tolerability 27

A single stereoisomeric change can dramatically alter the tolerability profile in vivo GalNAc conjugated Isomer1 Same sequence and chemical oligonucleotide administered modifications, but different stereochemistry subcutaneously Isomer2 Stereoisomers have similar Changing backbone stereochemistry leads to different hepatotoxicity profiles in vivo pharmacodynamic effects Target knockdown ALT AST Tnfrsf10b **** (liver) *** **** 1500 10000 150 15000 125 10000 5000 1000 100 5000 1000 75 1500 ns 750 500 50 1000 500 500 25 250 0 0 0 0 C57Bl/6 mice were administered 5 mg/kg oligonucleotide or PBS by subcutaneous injection on days 1, 3, 5 and 8. Liver tissue was collected on day 11. 28 Target mRNA was normalized to Hprt1. Data are presented as mean ± sem (n=5). Stats: One-way ANOVA ns not significant, PBS phosphate buffered saline, NTC non-targeting control Undisclosed target Percentage mRNA remaining ALT (U/L) AST (U/L) Tnfrsf10b (normalized to PBS)

Stereoisomeric changes can dramatically alter the tolerability profile in the CNS in vivo Unconjugated Isomer 1 Same sequence and chemical oligonucleotide administered modifications, but different stereochemistry ICV Isomer 2 Changing backbone stereochemistry leads to Stereoisomers have similar different tolerability profiles in vivo pharmacodynamic effects in vivo CNS target knockdown in vivo Percentage Body Weight Change 40 PBS 1.0 20 Isomer 1 Isomer 2 ns 0 0.5 -20 0.0 PBS Isomer 1 Isomer 2 7 14 21 28 35 42 49 56 Day Left: In a target engagement study, 7 mice administered 2 x 50 ug oligonucleotide or PBS by ICV on days 0 and 7. Tissue collected on day 14. Target 29 mRNA normalized to Tubb3 and plotted relative to PBS. Data presented as mean ± SD (n=7). Stats: One-way ANOVA ns not significant, PBS phosphate buffered saline. Right: wtmouse tolerability study, n=4 administered 100 ug oligonucleotide or PBS by ICV on day 0 and monitored for 8 weeks. Undisclosed target, relative to PBS Average % Body Weight Change

PRISM enables novel advances in oligonucleotide design for optimization of RNA therapeutics • PRISM uses deep understanding of interplay between sequence, chemistry and stereochemistry • Rationally placed PN backbone chemistry modifications improve potency, durability of effect and distribution in vitro and in vivo across silencing, including RNAi, splicing and editing modalities • Backbone stereochemistry can be a tool to modulate pharmacologic properties, including tolerability 30

Building a Best-in-Class RNA Editing Capability: Introduction of AIMers Chandra Vargeese, PhD Chief Technology Officer 31

Unlocking RNA editing with PRISM platform to develop AIMers: A-to-I editing oligonucleotides Free-uptake of chemically modified oligonucleotides • First publication (1995) ✓ Learnings from using oligonucleotide to biological concepts AIMer: edit RNA with 1 endogenous ADAR ✓ Applied to ASO structural concepts Wave’s A-to-I • Wave goal: Expand editing toolkit to include editing ✓ Applied PRISM oligonucleotides by unlocking ADAR with chemistry PRISM oligonucleotides ADAR enzymes • Catalyze conversion of A-to-I (G) in double- stranded RNA substrates ADAR RNase H • A-to-I (G) edits are one of the most Endogenous AGO2 common post-transcriptional modifications enzymes Spliceosome • ADAR1 is ubiquitously expressed across tissues, including liver and CNS 1 Woolf et al., PNAS Vol. 92, pp. 8298-8302, 1995 32

Building best-in-class ADAR editing capability Topics of discussion 1 2 3 Applications Design & Optimize Translation in vivo • Restore protein expression • Modulate protein activity 33

ADAR editing enables correction of single-point mutations to restore functional protein Restore functional protein Example therapeutic areas AIMer • AATD A I(G) • Rett syndrome Restore or • Recessive or correct dominant expression genetically defined diseases DNA 2 • >32,000 pathogenic human SNPs – nearly half are ADAR amenable (G-to-A mutations) 1 • Tens of thousands of potential disease variants A-to-I(G) editing could target 3 • ~12% of all reported disease-causing mutations are single point mutations that result in a premature stop codon SNP: single nucleotide polymorphism A: Adenosine I: Inosine G: Guanosine 34 1 2 3 ClinVar database Gaudeli NM et al. Nature (2017) Keeling KM et al., Madame Curie Bioscience Database 2000-2013

ADAR editing to modulate proteins at transcript level opens wide range of large therapeutic applications Modulate downstream protein interactions with single RNA base edit Example therapeutic areas AIMer Upregulate expression • Haploinsufficient Modify function diseases A I(G) • Loss of function Modulate protein- protein interaction• Neuromuscular • Dementias Post-translational modification• Familial epilepsies Alter folding (stability) • Neuropathic pain Alter processing • Opens wide range of therapeutic applications with large patient populations 35

Building best-in-class ADAR editing capability Topics of discussion 1 2 3 Applications Design & Optimize Translation in vivo • Restore protein expression• Applying unique chemistry capabilities to AIMers enhances • Modulate protein activity editing • Optimization of chemistry and SAR informs design principles for future rational design 36

Unique chemistry platform enables rational design of AIMers to efficiently recruit ADAR enzymes AIMers • RNA base editing oligonucleotides • Short, single-stranded • Fully chemically modified • Modified nucleobases • Stereopure PS and PN backbone modifications • Compatible with targeting ligands 37

Stereochemistry and PN chemistry enhance potency and editing efficiency of AIMers ACTB editing in primary human hepatocytes using GalNAc-mediated uptake 100 80 AIMer chemistry PS / PO / PN 60 PS / PO 40 (Stereopure) 20 PS / PO (Stereorandom) 0 -8 -6 -4 -2 0 2 10 10 10 10 10 10 Concentration (µM) Data from independent experiments; Total RNA was harvested, reverse transcribed to generate cDNA, and the editing target 38 site was amplified by PCR and quantified by Sanger sequencing % Editing

Levels of endogenous ADAR enzyme are not rate limiting for editing Primary Human Hepatocytes • Endogenous ADAR enzyme (transfection) supports editing on multiple independent targets ns 80 Single AIMer • Editing efficiency comparable Multiple AIMers targeting 60 even when additional AIMers different sequences “multiplex” targeting different sequences 40 are added, suggesting there is ns a more than sufficient reservoir of ADAR enzyme 20 0 ACTB EEF1A1 UGP2 Percentage A-to-I editing detected on the indicated transcripts in presence of 20 nM each of a single (Isolated) or multiple (Multiplex) AIMers after transfection of primary human hepatocytes (left), or in the presence of 1.1 mM each of a single (Isolated) or multiple (Multiplex) GalNAc conjugated 39 AIMers (right). Data are presented as mean ± SEM, n=3. P values as determine by two-tailed Welch’s t-test are indicated. NTC non-targeting control. Manuscript submitted. % Editing (Mean, s.e.m)

Optimization of every dimension to inform future rational design of AIMers Motif on target Sequence is one of multiple dimensions for optimization NNN AIMer Sequence space is defined XAX mRNA target • >300 unique AIMers tested containing different base pair combinations • Identified base modification combinations with high editing efficiency to optimize sequence Learnings inform design principles deployed across future targets 40 Motif on AIMer

ADAR interacts with double-stranded RNA duplex in a sequence independent way RNA-editing design applicable across targets in vitro in primary human hepatocytes AIMer 80 60 A 40 I(G) 20 0 • Editing achieved across several distinct RNA transcripts • The intrinsic function of ADAR is to recognize dsRNA independent of sequence • Supports potential for technology to be applied across variety of disease targets Data presented at 1st International Conference on Base Editing – Enzymes and Applications (Deaminet 2020). Manuscript submitted. 41 Transcript 1 Transcript 2 Transcript 3 Transcript 4 Transcript 5 Transcript 6 Transcript 7 Transcript 8 Percentage A® G editing

Building best-in-class ADAR editing capability Topics of discussion 1 2 3 Applications Design & Optimize Translation in vivo • Restore protein expression• Applying unique chemistry • GalNAc-conjugated AIMers: liver capabilities to AIMers enhances • Modulate protein activity• Unconjugated AIMers: CNS, editing ophthalmology and beyond • Optimization of chemistry and SAR informs design principles for future rational design 42

huADAR mouse enables optimization of AIMers to human ADAR Human ADAR expression in hepatocytes huADAR mouse Genotype Human ADAR1 ✓ huADAR/mADAR GAPDH Human ADAR expressed in all tissues • Transgenic mouse expressing Human ADAR expression in neurons human ADAR1 C57Bl/6 hADAR1 mouse mouse Human • Expression of ADAR in liver and Human ADAR1 neurons in mouse approximates expression in corresponding GAPDH human tissues Western blots showing expression of ADAR1 and GAPDH proteins in the indicated tissue 43 Left: Protein extracts from human hepatocytes, C57Bl/6 or hADAR1 mouse liver; Right: Protein extracts from cerebellum (Cereb), pons/medulla (pons/med), cortex (Ctx), midbrain (Mbrn), or human iCell neurons (iNeurons)

GalNAc-conjugated AIMers demonstrate proof-of concept of RNA editing in liver Rapidly advancing first therapeutic program Routes of Delivery administration Tissue types GalNAc-conjugated Subcutaneous Liver AATD program Unconjugated IVT Ophthalmology Intrathecal (IT) Central nervous system (CNS) PN-modified AIMers direct potent and durable editing in vivo 44

GalNAc-conjugated AIMers support efficient, durable and highly specific ADAR editing in NHPs Dose-dependent editing in Substantial and durable ADAR editing with ACTB AIMer is highly specific NHP hepatocytes in vitro editing in NHP liver in vivo RNA editing within full transcriptome (primary human hepatocytes) 100 Day 50 0.266 nM 1.332 nM RNA editing ACTB 6.66 nM in NHP 33.3 nM 75 50 AIMers 25 0% 0 ACTB-1 ACTB-2 ACTB-3 % Editing AIMers RNA editing only detected at editing site in ACTB transcript Left: Total RNA harvested, reverse transcribed to generate cDNA, and editing target site amplified by PCR; % Editing quantified from Sanger sequencing using EditR program; Center: 5mg/kg SC: Day 1,2,3,4,5; Liver Biopsy for mRNA (ACTB Editing); Right: Dosed 1um AIMer, 48 hours later RNA collected, RNAseq 45 conducted using strand-specific libraries to quantify on-target ACTB editing and off-target editing; plotted circles represent sites with LOD>3. Manuscript submitted. NHP: non-human primate; ACTB: Beta-actin % ACTB Editing Confidence (LOD score)

Unconjugated AIMers expand tissues amenable to ADAR editing Opportunity for future pipeline programs Routes of Delivery administration Tissue types GalNAc-conjugated Subcutaneous Liver Unconjugated MECP2 and IVT Ophthalmology undisclosed exploratory Intrathecal (IT) Central nervous system (CNS) programs PN-modified AIMers direct potent and durable editing in vivo 46

Up to 50% editing in vivo in the posterior of eye one month post-single IVT dose AIMers in retina Durable, dose-dependent editing post- at 4 weeks single intravitreal dose of UGP2 AIMer-1 80 80 60 60 50 ug 40 40 20 20 10 ug 0 0 PBS 10 ug 50 ug PBS 10 ug 50 ug 1 week 4 weeks Mice received a single IVT injection (10 or 50 ug AIMer), and eyes were collected for RNA analysis and histology 1 or 4 weeks later. Left: editing evaluated by Sanger sequencing, and % RNA editing calculated with EditR. PBS 47 Right: FFPE and RNA scope assay specific for AIMer, red = oligo, blue = nuclei. Posterior region: retina, choroid, sclera. %UGP2 mRNA editing %UGP2 mRNA Editing

AIMers direct editing in vitro in multiple CNS cell types and throughout CNS in vivo Editing in CNS of hADAR mouse In vitro dose-response (Single ICV injection, 100 mg) 80 100 UGP2 AIMer-1 *** *** 80 UGP2 AIMer-1 60 PBS *** 60 *** 40 40 ** ** 20 20 0 0 0.01 0.1 1 10 100 1 2 3 4 5 6 Concentration (mM) iNeurons iAstrocytes hADAR: human ADAR; UGP2: Glucose Pyrophosphorylase 2; CNS: central nervous system; Editing observed across all tested tissues of huADAR- 48 transgenic mice. N=5 PBS or single 100 mg ICV dose on day 0, necropsied on day 7. RNA harvested, editing measured by Sanger sequencing. ACTB b- actin; Stats: *p<0.05; **p<0.01; ***p<0.001; ****p<0.0001; all comparisons to PBS-treated group by t test (P values Bonferroni corrected) % Editing % Editing

Substantial in vivo RNA editing out to at least 4 months post-single dose in CNS tissues UGP2 AIMer-1 Peak RNA editing observed one-month post-single dose across tissues PBS Cortex Hippocampus Striatum Brain stem Cerebellum Spinal cord 80 80 80 80 80 80 **** ** ** 60 60 60 60 60 60 ** **** * *** * ** * *** *** * *** *** *** ** *** **** 40 40 40 40 40 40 ** * ** ** ** ** * 20 20 20 20 20 20 0 0 0 0 0 0 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 PBS PBS PBS PBS PBS PBS Weeks Weeks Weeks Weeks Weeks Weeks Peak 30% >40% 25% >40% 50% >65% editing Transgenic huADAR mice administered 100 mg AIMer or PBS on day 0 and evaluated for UGP2 editing across CNS tissues at 1, 4, 8, 12, and 16- 49 weeks post dose. Percentage UGP2 editing determined by Sanger sequencing. Stats: 2-way ANOVA compared to PBS (n=5 per time point per treatment) *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001. ICV intracerebroventricular; PBS phosphate buffered saline % UGP2 editing

UGP2 AIMer-1 distributes throughout CNS Spinal cord Frontal cortex Hippocampus Cerebellum 50 Sections from treated mice 12-weeks after a single 100 mg dose of UGP2-AIMer or PBS (bottom). ViewRNA (red, Fast red) was used to detect oligonucleotides; sections are counterstained with hematoxylin (blue nuclei). Magnification 10X (top & bottom), 40X (middle, oil), 10X PBS UGP2

Achieving productive editing in multiple NHP tissues with unconjugated systemic AIMer delivery ✓ GalNAc-conjugated (Targeted - subcutaneous) Editing in NHP 1-week post-single dose ✓ Unconjugated (Local – IVT, IT) SC administration 60 ✓ Unconjugated (Systemic) 40 • NHP study demonstrated productive editing in 20 kidney, liver, lung and heart with single subcutaneous dose 0 PBS ACTB AIMer NHP: non-human primate; ACTB: Beta-actin 51 Dose: 50 mg/kg SC on Day 1 Necropsy for mRNA (ACTB Editing) Day 8 % ACTB editing

Achieving productive editing in multiple immune cell types with AIMers in vitro ACTB AIMer Mock Human peripheral blood CD4+ T-cell ***** mononuclear cell CD4 (PBMC) CD8+ ***** T-cell CD8 CD14 ***** CD14 Monocytes CD19 ***** CD19 B-cell NK NK ***** NK-cell Tregs ***** Treg T-cell Activate (PHA) → Dose → Sort 0 20 40 60 80 100 % ACTB Editing Human PBMCs dosed with 10 uM ACTB AIMers, under activating conditions (PHA). After 4 days, different cell types isolated, quantitated for editing %. 52 ACTB: Beta-actin; Two-way ANOVA followed by post hoc comparison per cell line. P values were Bonferroni-corrected for multiple hypotheses

Ongoing chemistry optimization continues to drive potency gains In vitro dose-response in iCell neurons 80 60 ~75% more efficient editing 40 with optimized AIMers 20 0 1.0 3.0 1.0 3.0 Concentration (mM) Initial Optimized chemistry chemistry iCell neurons treated with 1 or 3 mM UGP2 AIMer with old (left, blue) or new (right, green) chemistry. Data are mean ± sd. 53 % UGP2 editing

Rapidly advancing best-in-class ADAR editing capability Principles of PRISM rational chemistry capabilities design Efficient, Leverages durable and AIMers endogenous highly specific RNA editing ADAR editing in oligonucleotides enzymes multiple tissues Compatible In vivo with GalNAc for models editing in liver 54

Advancing ADAR Editing in the CNS Ken Rhodes, PhD SVP, Therapeutics Discovery 55

Substantial in vivo RNA editing out to at least 4 months post-single dose in CNS tissues UGP2 AIMer-1 Peak RNA editing observed one-month post-single dose across tissues PBS Cortex Hippocampus Striatum Brain stem Cerebellum Spinal cord 80 80 80 80 80 80 **** ** ** 60 60 60 60 60 60 ** **** * *** * ** * *** *** * *** *** *** ** *** **** 40 40 40 40 40 40 ** * ** ** ** ** * 20 20 20 20 20 20 0 0 0 0 0 0 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 1 4 8 12 16 PBS PBS PBS PBS PBS PBS Weeks Weeks Weeks Weeks Weeks Weeks Peak 30% >40% 25% >40% 50% >65% editing Transgenic huADAR mice administered 100 mg AIMer or PBS on day 0 and evaluated for UGP2 editing across CNS tissues at 1, 4, 8, 12, and 16- 56 weeks post dose. Percentage UGP2 editing determined by Sanger sequencing. Stats: 2-way ANOVA compared to PBS (n=5 per time point per treatment) *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001. ICV intracerebroventricular; PBS phosphate buffered saline % UGP2 editing

Expanding addressable disease target space using ADAR editing to modulate proteins ADAR editing of Impact diseases Restore or modify protein function mRNA Post- Examples: Correction translational modification • Familial epilepsies • Neuropathic pain I(G) • Neuromuscular disorders Folding Upregulation • Dementias (stability) • Haploinsufficient diseases • Loss of function Protein- Processing protein interaction 57

Correct a nonsense mutation using ADAR editing to restore protein expression and function ADAR editing of Downstream protein interactions mRNA Post- Correction translational modification I(G) Folding Upregulation (stability) Protein- Processing protein interaction 58

RNA editing of nonsense mutation found in MECP2 (Rett Syndrome) restores functional protein Nonsense mutations found in Rett Syndrome can occur in multiple locations on RNA transcript: Normal: … CGA… wild type protein Variant base Rett Syndrome: … TGA… premature stop codon ADAR editing site ADAR editing: … TGG… restored protein in vitro ADAR editing of over 60% targeting Full length MECP2 protein is expressed MECP2 disease transcript following ADAR editing PN chemistry improved editing Dose-dependent RNA editing of efficiency in vitro MECP2 mutation with PS/PN AIMer PS/PN AIMer 100 WV-40573 + Dosed with hADAR hADAR 100 WV-40573 - hADAR Control (no hADAR) 80 ADAR Edited MECP2 80 Endogenous MECP2 60 60 Loading Control 40 40 20 20 0 0 mock PS PS-PN 0.0001 0.001 0.01 0.1 1 10 100 [nM] 293T cells transfected with both nonsense mutation on MECP2 (GFP-fusion construct) and ADAR plasmids. AIMers transfected for 48h prior to RNA extraction and sequencing. Percentage editing determined by Sanger sequencing. Left: Single dose (25nM) treatment Middle: Full dose response curve 59 (25nM, 5-fold dilution, 48h treatment) in presence or absence of hADAR Right: Western blot for MECP2 protein. Three biological replicates, NTC AIMer, mock and naïve 293T cells probed for fusion protein. Percentage A® G editing Percentage A® G editing Ladder NTC Mock Naive

Restored MECP2 retains proper nuclear localization Functional domains on MECP2 Cytoplasm Nucleus R168W R168W 125 Mock WT 90 FLAG MECP2 70 GAPDH 38 (Loading Control Cytoplasm) 30 25 Histone H3 DAPI FLAG (Loading Control Nucleus) 15 293T cells transfected with plasmids containing either wildtype or R168W MECP2 (FLAG-fusion construct) for 72hr. Left: Immunofluorescence staining with anti-FLAG monoclonal antibody (green), nuclei were counterstained with DAPI (blue). Right: Western blot analysis of cellular fractionation to 60 isolate cytoplasm and nucleus. Mock, WT MECP2, and two biological replicates of MECP2 (R168W) transfected 293T cells probed for FLAG-tagged MECP2 protein. Mock WT R168W R168W Mock WT R168W R168W

Restored MECP2 binds to coregulatory proteins and recruits HDAC3, further suggesting functional restoration Functional domains on MECP2 90 FLAG 70 R168W MECP2 NCoR/SMRT complex NCoR1 260 90 TBLR1 70 IgG Heavy Chain HDAC3 50 NCoR1 - Transcriptional coregulatory proteins that facilitates the recruitment of HDAC3 to DNA promoter regions TBLR1 - Scaffold protein facilitating assembly of multi-protein complexes HDAC3 – Histone deacetylase that removes acetyl group from histones, allowing histones to wrap DNA more tightly and suppress target gene expression 293T cells transfected with plasmids containing either wildtype or R168W MECP2 (FLAG-fusion construct). Transfected for 72h prior to nuclear 61 extraction and immunoprecipitation with anti-FLAG tagged magnetic beads. Right: Western blot analysis of immunoprecipitation eluates probed for FLAG-tagged MECP2 protein and NCoR1/SMRT complex. Mock WT R168W

ADAR editing to modulate protein-protein interactions: upregulating gene expression ADAR editing of Downstream protein interactions mRNA Post- Restore translational modification I(G) Folding Upregulation (stability) Protein- Processing protein interaction 62

ADAR to modify protein-protein interactions Basal conditions KEAP1 Nrf2 Nrf2 is degraded Transcription is repressed Nrf2-mediated gene transcription program KEAP1 binds Nrf2, targeting Nrf2 for proteosomal degradation and repressing Nrf2 mediated gene transcription 63

ADAR to modify protein-protein interactions Basal conditions ADAR modified pathway ADAR editing KEAP1 KEAP1 sites Nrf2 Nrf2 is stabilized Nrf2 is degraded Nrf2 translocates to nucleus and activates gene expression Transcription is repressed Nrf2 mediated gene Nrf2 activated genes Nrf2 transcription {A:B:C:D} {A:B:C:D} ADAR editing to change one amino acid in KEAP1 or Nrf2 KEAP1 binds Nrf2, destabilizing Nrf2 and repressing could allow for stabilization of Nrf2 and activation of Nrf2 Nrf2 mediated gene transcription mediated gene transcription 64

ADAR editing alters multiple amino acids on two different proteins in vitro Amino acid targets Changed amino acid 10 Control 9 Tyr Cys AIMer 1 8 Arg Gly AIMer 2 → Evaluated gene 7 Tyr Cys AIMer 3 KEAP1 transcription 6 Asn Asp AIMer 4 ADAR 5 Tyr base Cys AIMer 5 editing 4 Asn Asp AIMer 6 Ser Gly AIMer 73 Ser Gly AIMer 82 His Arg AIMer 91 % Editing mRNA1 (KEAP1) Amino acid targets Changed amino acid % Editing mRNA1 (Protein-1) 8 Control 7 Gln Arg AIMer 10 6→ Evaluated gene Ile Val AIMer 11 transcription 5 Asp Gly AIMer 12 ADAR 4 Nrf2 Glu Gly base AIMer 13 editing 3 Glu Gly AIMer 14 2 Glu Gly AIMer 15 1 Asp Gly AIMer 16 293T cells transfected with 20nM of AIMer, ADAR-p110 or ADAR-p150 plasmid. RNA collected 65 % Editing mRNA2 (Nrf2) 48h, editing quantified by PCR and Sanger (n=2). % Editing mRNA2 (Protein-2) 0 20 40 60 80 0 100 20 40 60 80 100

ADAR editing activates multiple genes confirming disrupted protein-protein interaction in vitro ADAR editing of either KEAP1 or Nrf2 directs gene activation Control SLC7a11/mRNA-B Contro 1l0 Contro 1l0 NQO1/mRNA-A Control Control Control 9 9 AIMer 1 AIMer 18 8 AIMer 2 AIMer 2 7 7 AIMer 3 AIMer 3 6 6 KEAP1 AIMer 4 AIMer 4 5 5 AIMer 10 AIMer 10 4 4 AIMer 11 AIMer 11 3 3 AIMer 12 AIMer 12 2 2 AIMer 13 AIMer 13 1 1 Fold increase over control Fold increase over control Control Control HMOX1/mRNA-C SRGN/mRNA-D 10 10 Control Control 9 9 AIMer 1 AIMer 1 8 8 AIMer 2 AIMer 2 7 7 AIMer 3 AIMer 3 6 6 AIMer 4 5 AIMer 4 5 AIMer 10 4 AIMer 10 4 AIMer 11 3 AIMer 11 3 Nrf2 mediated gene AIMer 12 2 AIMer 12 Nrf2 2 transcription {A:B:C:D} AIMer 13 1 AIMer 13 1 Fold increase over control Fold increase over control Gene expression quantified by PCR (n=2) 66 0 5 10 15 0 20 5 10 15 20 0 100 200 300 400 500 0 5 10 15

ADAR editing expands target universe in CNS • PN chemistry expands addressable CNS disease target space, enabling protein restoration and protein modulation by leveraging shared learnings across ADAR programs – Editing of UGP2 in vivo in CNS tissues is durable out to 4 months – Discovery-stage MECP2 program for Rett Syndrome demonstrates restoration of functional MECP2 protein with ADAR editing in vitro to correct nonsense mutation – Disrupting protein–protein interactions enables access to new mechanisms 67

Restoring Functional AAT Protein with ADAR Editing: Program Update Paloma Giangrande, PhD VP, Platform Discovery Sciences 68

Leading RNA editing program provides optimal approach for treatment of AATD 1) Restore circulating, 2) Reduce Z-AAT protein 3) Retain M-AAT physiological functional wild-type M-AAT aggregation in liver regulation Risk of disease Highest Null risk (lung) (no AAT) Z-AAT High PI*ZZ (lung + liver) PI*SZ Wild-type M-AAT protein M-AAT reaches lungs to protect M-AAT secretion into bloodstream replaces Z-AAT with RNA from proteases correction Low PI*MZ Wave ADAR editing approach addresses all goals of treatment Normal PI*MM GalNAc-conjugated for subcutaneous delivery ~200K people in US and EU with mutation in SERPINA1 Z allele (PI*ZZ) AAT: Alpha-1 antitrypsin; Sources: Strnad 2020; Blanco 2017 69

Today’s update on AATD program Demonstrate restoration of Assess specificity and Chemistry optimization to Path to development functional M-AAT candidate duration of effect improve potency 70

3-Fold increase Focused on restoring wild-type M-AAT in vivo In vitro proof of concept In vivo proof of concept SERPINA1 Z allele mRNA editing 1 0 0 8 0 6 0 4 0 2 0 0 NT SA1-1 SA1-2 Liver AAT aggregation observed in AATD is recapitulated in AAT protein concentration in media mouse model * * *** * 6 0 0 0 4 0 0 0 2 0 0 0 NT SA1-1 SA1-2 AATD: Alpha-1 antitrypsin deficiency, Z-AAT: mutated protein, M-AAT: wild-type human AAT protein 71 (Left) Hematoxylin and PAS stain and (Right) immunohistochemistry for AAT protein with hematoxylin counterstain in the huADAR/AATD mouse liver N T S A 1 -1 S A 1 -2 N T S A 1 -1 S A 1 -2 AAT Protein ng/ml % Z allele mRNA editing S e r p in A 1 P r o te in n g /m l % S e r p in A 1 -P IZ m R N A E d itin g

Achieving 40% editing of Z allele mRNA at single time point SERPINA1 Z allele mRNA editing levels nearing correction to heterozygote (MZ) SERPINA1 editing huADAR SERPINA1 editing huADAR mouse hepatocytes SA1-3 100 50 SA1-4• GalNAc-conjugated compounds **** 80 40 **** • Up to 40% editing of Z allele 60 30 mRNA in liver of transgenic human ADAR mice at day 7 40 20 20 10 0 0 0.001 0.01 0.1 1 10 UGP2 PBS SA1 - 3 SA1 - 4 NTC Concentration (mM) AIMers Z allele mRNA editing in vivo AAT protein increase Wild-type M-AAT functional huADAR/SERPINA1 mice administered PBS or 3 x 10 mg/kg AIMer (days 0, 2, and 4) SC. Samples collected day 7. Stats: One-way ANOVA; NTC: non- 72 targeting control % Editing % Editing

ADAR editing is highly specific; no bystander editing observed on SERPINA1 transcript RNA editing only detected at PiZ mutation site in SERPINA1 transcript RNA editing within transcriptome (mouse liver) (mouse liver) C 0% SERPINA1 PBS (PiZ mutation site) T 100% C 48.2% SA1-4 AIMer T 51.8% % Editing Editing site (PiZ mutation) Highly specific Z allele mRNA AAT protein increase Wild-type M-AAT functional editing in vivo Mice were at dosed at 3 x 10mg/kg on days 0, 2, and 4 SC. Liver biopsies were collected on day 7. RNAseq was conducted 73 using strand-specific libraries. To quantify on-target SERPINA1 editing reads were mapped to human SERPINA1 and to quantify off-target editing reads were mapped to entire mouse genome; plotted circles represent sites with LOD>3 (N=4) Coverage Coverage

Achieving therapeutically meaningful increases in circulating human AAT protein 3-fold increase in circulating human AAT as compared to PBS at initial timepoint Human AAT concentration in serum AAT serum levels by genotype 800 3-fold increase at day 7 PI*MZ ~3 to 5-fold increase 600 **** 11µM PI*SZ ~2-fold increase **** 400 n.s PI*ZZ ~3 – 7 uM 200 0 PBS UGP2 SA1-3 SA1-4 NTC Pre-dose Day 7 Z allele mRNA editing in vivo AAT protein increase Wild-type M-AAT functional Statistics (ELISA): Matched 2-way ANOVA with correction for multiple comparisons (Bonferroni) was used to test for differences in AAT abundance in 74 treated samples compared to PBS Statistics; de Serres et al., J Intern Med. 2014; NTC: non-targeting control Serum AAT (mg/ml)

ADAR editing restores circulating, functional M-AAT Significant increase in neutrophil Wild-type M-AAT detected with ADAR editing elastase inhibition with ADAR editing 3-fold increase in total AAT 100 ~2.5-fold increase 600 Pre-dose **** 80 Day 7 Human *** 60 wild-type 300 M-AAT n.s 40 20 0 0 PBS UGP2 SA1-3 SA1-4 NTC PBS SA1-4 Z allele mRNA editing in vivo AAT protein increase Wild-type M-AAT functional Left: Mass spectrometry and ELISA Right: (Elastase inhibition): Matched 2-way ANOVA with correction for multiple comparisons (Bonferroni) was used 75 to test for differences in elastase inhibition activity in serum collected at day 7 vs pre-dose for each treatment group; NTC: non-targeting control Pre-dose Day 7 Pre-dose Day 7 Serum AAT protein (ug/ml) (Mean, s.e.m) % Relative Elastase Inhibition

Increase in circulating human AAT is durable, with restored M-AAT detected one month post last dose Human AAT serum concentration ≥3-fold Restored wild-type M-AAT detected over higher over 30 days post-last dose 30 days post-last dose 800 M-AAT production 800 *** *** Elevated Z-AAT at Day 35 600 11 mM 600 suggests clearance of ** intracellular Z-AAT ** aggregates with AIMers ns 400 400 *** 200 200 0 0 0 7 14 21 28 35 0 35 0 7 14 21 28 35 Days Days SA1-4 PBS Dose SA1-4 PBS Z-AAT (mutant) M-AAT (wild type) SA1-4: GalNAc AIMer (Left) huADAR/SERPINA1 mice administered PBS or 3 x 10 mg/kg AIMer (days 0, 2, and 4) SC. AAT levels quantified by ELISA. 76 Data presented as mean ± sem. Stats: Matched 2-way ANOVA ns nonsignificant, ** P<0.01, *** P<0.001. (Right) Proportion of AAT in serum, Z type (mutant) or M type (wild type), measured by mass spectrometry, total AAT levels quantified by ELISA Serum AAT mg/mL Serum AAT mg/mL

Optimization further improves potency 50% mean editing observed with half dose in mice at Day 7 SERPINA1 RNA editing huADAR mouse with GalNAc AIMers Chemistry optimization: (3x5 mg/kg, SC) ✓ Increases Z allele mRNA * editing efficiency * 60 50% editing 40 20 0 PBS SA1-4 SA1-5 SA1-6 Initial Optimized chemistry chemistry AIMers administered huADAR/SERPINA1 mice (3x5 mg/kg) on days 0, 2, and 4. Livers collected on day 7, and SERPINA1 editing was quantified by 77 Sanger sequencing (shown as mean ±. sem) Stats: One-way ANOVA was used to test for differences in editing between SA1-4 and other oligos * P<0.05 % Editing

Optimization further improves M-AAT restoration 4-fold increase in AAT protein (>15uM) relative to PBS at Day 7 with optimized AIMer Initial chemistry Opti Opti mimi zed zed che che mimi strsy try AAT concentration in serum AAT concentration in serum Chemistry optimization: 4-fold increase in 1000 1000 ✓ Increases Z allele mRNA total AAT editing efficiency 800 800 85% ✓ Higher fold-increase in 3-fold increase M-AAT circulating AAT protein in total AAT relative to control 600 600 11 mM ✓ Greater percentage of restored wild-type M-AAT 75% 400 400 protein relative to total AAT M-AAT 200 200 0 0 M-AAT (wild-type) Z-AAT (mutant) PBS SA1-4 PBS SA1-5 huADAR/SERPINA1 mice administered PBS or 3 x 10 mg/kg AIMer (days 0, 2, and 4) SC. Proportion of AAT protein in serum, Z type or M type, measured 78 by mass spectrometry, total AAT protein levels quantified by ELISA. Pre-dose Day 7 Pre-dose Day 7 Pre-dose Day 7 Pre-dose Day 7 Serum AAT protein (ug/ml) Serum AAT protein (ug/ml) (M (M ea ean n, s,. e s. .m e.)m) Serum AAT protein (ug/ml) Serum AAT protein (ug/ml) (Mean, s.e.m) (Mean, s.e.m)

AATD development candidate expected in 2022 Demonstrate restoration of Path to development Assess specificity and Chemistry optimization to functional M-AAT duration of effect improve potency candidate ✓ GalNAc-conjugated ✓ ADAR editing is highly ✓ Chemistry optimization of • Ongoing and planned AIMers restore specific AIMers further increases preclinical studies therapeutically potency assessing durability, dose ✓ Restored, circulating meaningful levels of response and PK/PD wild-type M-AAT in serum ✓ Optimized AIMers restore functional, wild-type M- at 1-month post-last AAT in serum by 4-fold • Assessment of reduction AAT dose (>15uM) at Day 7 in Z-AAT aggregates and changes in liver ✓ Restored wild-type M-AAT pathology at 85% of total AAT 79

Closing Remarks Paul Bolno, MD, MBA President and CEO 80

Q&A Dr. Paul Bolno Dr. Chandra Vargeese President and Chief Technology Officer Chief Executive Officer Dr. Paloma Giangrande Dr. Ken Rhodes VP, Platform Discovery SVP, Therapeutics Discovery Sciences, Biology 81 81

Realizing a brighter future for people affected by genetic diseases For more information: Kate Rausch, Investor Relations krausch@wavelifesci.com 617.949.4827 82 82