Korro Bio : May 2026 Corporate Presentation
KRRO
Published on 05/07/2026 at 07:35 am EDT
MMaayr2c0h2260C2o5rporate Presentation
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Our Vision
3
3
Activating Biological Pathways
Editing RNA
Without permanently modifying DNA
Modular Delivery
Potential to deliver to multiple cell types
Learning from Genetics
To support predictable biological impact
4
4
Positioned for Value Creation in 2026 and Beyond
Regulatory filing for KRRO-121 anticipated in H2 2026
Development Candidate (DC) announcement for GalNAc-conjugated alpha-1 antitrypsin deficiency (AATD) construct expected in Q2 2026
DC expected for a 3rd GalNAc-conjugated liver asset in H2 2026
Cash runway into H2 '28 enabling multiple milestones 1
Potential for partnership across our pipeline
1. Cash, cash equivalents and marketable securities of $157.1 million as of March 31, 202G 5
Leveraging known mechanisms to derisk Delivery
Expertise in Chemistry driving potency and drug designs
OPERA: Our Approach for RNA Editing to Generate Product Candidates
Expertise in ADAR biology driving potency and translation
Expertise in Machine Learning driving efficiency and Target ID
G
RNA Editing Enables Potential for High Impact in Range of Disease Areas
DNA
Protein
Pre-mRNA mRNA
TRANSCRIPTION PROCESSING TRANSLATION
Edit a single A-to-I
Modifying gene expression
Edit a single A-to-I
Repair a G->A mutation to correct the protein
Generate a de novo protein with preferred properties (can alter 12 amino acids)
Current Focus
Human genetics guiding the possibilities
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Pipeline Programs Primarily Focused on Generation of De Novo Proteins
Modulate Protein Function (Activate pathway)
TRANSLATION
RNA
Normal Protein
TRANSLATION
Edited RNA
De Novo Protein
Repair the Protein
RNA with a missense
TRANSLATION
Pathogenic mutant protein
Edited RNA
TRANSLATION
Normal "corrected"
protein
Examples of Repair= E342KAATD,G2016S Parkinson
Disease,Dravet'sSyndrome…
ExamplesofModulate = Hyperammonemia, ALS, MASH,
Fibrosis…
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CONCEPT
PROGRAM / INDICATION
DELIVERY
DISCOVERY
PRECLINICAL DEVELOPMENT
PHASE 1
PHASE 2
PHASE 3
Pipeline with Potential High-Value Programs and Anticipated Milestones
Stabilize Protein
KRRO-121
Hyperammonemia
GalNAc (SC)
GS
Reg filing in 2H 2026
Repair Pathogenic Variant
AATD
GalNAc (SC)
AAT
DC in 2Q 2026
Allosteric Activator
Longevity (Liver)
GalNAc (SC)
AMPK1
Overcome LoF and GoF 1
Amyotrophic
lateral sclerosis (ALS)
Intrathecal (IT)
TDP43
Protein repair
De Novo protein creation
1De Novo protein prevents toxic gain-of-function (GoF) with TDP43 aggregation, and continue downstream signaling by overcoming toxic loss-of-function (LOF)
GS = Glutamine Synthetase; AAT = Alpha-1 antitrypsin; AATD = AAT deficiency; AMPK 1 = Regulatory subunit of AMP-activated protein kinase; TDP43 = TAR DNA-binding protein 43; DC = Development Candidate
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Synthetic Rescue
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Plasma Ammonia Significantly Impacts Pathology Across Multiple Diseases
Ammonia Pathology
Diet &
High ammonia leads to:
- Neurological impairment, potentially permanent
metabolism Normal
Clearance
Ammonia
Diminished Clearance
Normal excretion through kidneys
Hyperammonemia
Frequent hospitalization
Highly restricted diet
Elevated infection risk
Additional non-neurological complications
Can be caused by cirrhosis or urea cycle dysfunction
Clinical studies have shown benefit of
lowering ammonia in multiple indications
Source: 3rd party primary market research study and analysis (April 2025); KOL interviews 11
Two Complementary Pathways for Ammonia Clearance: Urea Cycle and Glutamine Synthetase (GS)
Urea Cycle
Ammonia
OTC
CPS-1
ARG
Urea Cycle
ASS
Urea
ASL
Expressed primarily in liver
Glutamine Synthetase
Glutamate
Ammonia
Glutamine
synthetase
Glutamine
Expressed in many tissues, including liver, brain, and muscle
Source: Inoue at al., Seizure (2015); Bennet et al., Child Neurology Open (2020); Jones et al., The American Journal of Human Genetics (2024); Soria et al., J Inherit Metab Dis (2019); KOL interviews
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Degradation of GS Controlled by Levels of Glutamine
Glutamine Drives Degradation of GS
Degradation Mechanism: Acetylation of Key N-terminal Residues
Glutamate Ammonia
Low glutamine
High glutamine
Glutamine
Glutamine
synthetase
GS Degradation
N
N
Lys Lys
Ac Ac
Glutamine
synthetase
Glutamine
synthetase
Ubiquitination
signal
Degradation
GS degraded when glutamine rises, reducing ammonia clearance capacity
No lysine acetylation, GS is stable
Acetylation of lysine residues, leading to ubiquitination and protein degradation
Source: Van Nguyen et al., Mol Cell (2017)
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Our Approach: Liver-specific, GalNAc-Oligo to Generate a Stabilized, De Novo GS Protein
Liver directed editing (GalNAc delivery)
A
GalNAc
Glutamine synthetase
N Designed to maintain
Arg Lys
consistent ammonia
clearance capacity
I (G)
KRRO-121 GS mRNA
Edited GS mRNA De novo GS protein
KRRO-121: GalNAc-conjugated oligonucleotide designed for liver-specific RNA editing of GS to enhance ammonia clearance capacity
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KRRO-121 Stabilized GS in UCD-derived Human Cell Models
OTC iPSC
KRRO-121
KRRO-121 Stabilized GS in OTC-Deficient iPSC-Derived Hepatocytes
GS degradation
non treated
10 mM NH4Cl
✱✱✱
1.0
1.0
0.9
G
s o
0.4
Fold Change to Vehicle
3
2
S remained
table upon ligo treatment
1
Similar results in ASS1-deficient
iPSC-derived
hepatocytes
0
Vehicle KRRO-121 (10 μM)
20-25% editing observed in oligo-treated cells
Note: OTC D175V human iPSC-derived hepatocytes differentiated for 14 days, then treated with oligo for 48 hours where indicated (10 mM NH4Cl added after 24 hours where indicated).
GS concentration measured at conclusion of 48-hour incubation.
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Ammonia Reduction in OTC-Deficient Mice Challenged with Ammonia Supports Clinical Activity, Diet Liberalization
OTCspf/ash
Improved Clearance in Ammonia Challenge Supports Potential to Increase Protein Intake
Nonsignificant Increase in Plasma Glutamine Levels
1000
Ammonia (µM)
800
2500
Vehicle
Mouse-optimized oligo
2000
600
400
200
Fasted ammonia
ULN: 450 μM
(human range 75 μg/dL)
1500
Blood Gln (μM)
1000
500
0
14
Ammonia challenge designed to
model patient protein consumption
Day
0
Day 14
Note: Vehicle or Mouse-optimized oligo dosed at 10 mg/kg-SC daily on Days 0-4. Ammonia and glutamine measured following ammonia challenge (150 mg/kg) on Day 14
1G
ns
ns
Ammonia Reduction in CPS-1 Deficient Mice Further Validates Potential Pan-UCD Applicability and Diet Liberalization
CPS-1
Reduction in Ammonia Following Ammonia Challenge
Nonsignificant Increase in Plasma Glutamine Levels
ns
2000
p < 0.05
1500
Vehicle
Mouse-optimized oligo
Ammonia (μM)
Blood Gln (μM)
1500
1000
1000
500
500
0
Baseline Post Challenge
0
Baseline Post Challenge
"… Korro's RNA editing approach targeting glutamine synthetase in hepatocytes has been proven to effectively
redirect excess toxic ammonia towards the synthesis of glutamine in UCD animal models …"
- Nicola Brunetti-Pierri MD and Leandro R. Soria PhD
Note: Vehicle or Mouse-optimized oligo dosed at 10 mg/kg-SC daily on Days 0-4. Ammonia and glutamine measured following ammonia challenge (150 mg/kg) on Day 8.
Data generated in collaboration with Dr. Nicola Brunetti-Pierri and Leandro R. Soria.
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KRRO-121 Has Blockbuster Potential in Multiple Indications
Addressable
Patients
Urea Cycle Disorders
(UCD)
4,200 U.S.1
5,100 EU + UK1
Hepatic
Encephalopathy (HE)
80,000 U.S.2
150,000 EU + UK3
Market Opportunity
$1.5B $2B+
Note: 1. Severe late-onset UCD patients; 2. Patients prescribed rifaximin +/- lactulose with ≥1.5x normal ammonia and satisfactory liver function as assessed by laboratory values; 3. EU + UK estimate applies U.S. epidemiology
assumptions to estimated EU + UK cirrhosis population
Source: 3rd party primary market research study (April 2025); KOL interviews; GlobalData; Electronic medical records analysis (data from 2022). All figures approximate.
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KRRO-121 Can Potentially Address Patients Across All UCD subtypes and Expand Current Nitrogen Scavenger Market
U.S. UCD Epidemiology
6,500
UCD patients
4,600
post-neonatal onset1
4,200
severe2
5,100
additional addressable
patients in EU + UK
UCD Market Share (2026)1
~10,000 late-onset patients (US + EU/UK)
Diet + Scavengers
20-30%
45-55%
Undiagnosed
20-30%
Diet Alone or Untreated
Note: 1. Onset of symptoms at age >1 month; 2. Severe defined as symptomatic patients expected to benefit from pharmacological therapy. Carbaglu (NAGS) and Loargys (ARG) not shown (collectively addresses <5% of market). Supplements not shown.
Source: 3rd party primary market research study (April 2025); KOL interviews; GlobalData. All figures approximate. Martin-Hernandez et al., Nutrients (2025); Burrage et al., Mol Genet Metab (2014); Company estimates; Analyst reports; KOL interviews
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KRRO-121: A Potential First-in-class Treatment For Ammonia Control
Preclinical Activity
Preclinical Safety
Demonstrated Translation
Pan-UCD potential impacting multiple UCD subtypes
Robust ammonia control in OTC and CPS-1 mice challenged with ammonia1
Diet liberalization potential demonstrated by ammonia reduction during protein challenge
NHP: No adverse safety signals in repeat QWx3 dose range finding tox studies
NHP: No impact on coagulation, complement, platelets, cytokines
No evidence of editing observed in
mouse brain tissue
No increase in mouse astrocyte staining in KRRO-121 treated mice relative to vehicle treatment
Production of stable, de novo GS protein which increased ammonia clearance and maintained normal glutamine levels
Scaled from mouse to monkey and showed targeted liver delivery
Strong preclinical data support KRRO-121's anticipated regulatory submission
Note: 1. As demonstrated using a surrogate mouse-optimized oligo
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Disclaimer
Korro Bio Inc. published this content on May 07, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on May 07, 2026 at 11:32 UTC.