Forward Looking Statements 2023 Aeglea BioTherapeutics This presentation and the accompanying oral presentation contain "forward-looking" statements that are based on our management's beliefs and assumptions and on infor

Redefining the Possible. Human Enzyme

Therapies for People with Rare Diseases Corporate Overview - January 2023 Nasdaq: AGLE Exhibit 99.1

Forward Looking Statements 2023

Aeglea BioTherapeutics This presentation and the accompanying oral presentation contain "forward-looking" statements that are based on our management's beliefs and assumptions and on information currently available to management.

Forward-looking statements include all statements other than statements of historical fact contained in this presentation, including information concerning our current and future financial performance, business plans and objectives, current and

future clinical and preclinical development activities, timing and success of our ongoing and planned clinical trials and related data, the timing of announcements, updates, results of our clinical trials and related data, our ability to obtain and

maintain regulatory approval, the potential therapeutic benefits, safety profile and economic value of our product candidates, potential growth opportunities, financing plans, use and adequacy of financing plans, the length of time that we believe

our existing cash resources will fund operations, competitive position, industry environment and potential market opportunities. Forward-looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors

including, but not limited to, those related to the success, cost and timing of our product candidate development activities and ongoing and planned clinical trials; our plans to develop and commercialize targeted therapeutics, including our lead

product candidates pegzilarginase and pegtarviliase and our other product candidates; the design, progress of patient enrollment and dosing in our clinical trials; the ability of our product candidates to achieve applicable endpoints in clinical

trials; the safety profile of our product candidates in clinical trials; the potential for data from our current and future clinical trials to support a marketing application, as well as the timing of these events, including data for our Phase 1/2

trial of pegtarviliase (AGLE-177) in Classical Homocystinuria; the potential for preclinical studies to be predictive of current or future clinical trials; our ability to obtain funding for our operations, development and commercialization of our

product candidates; the impact of the COVID-19 pandemic on our operations and clinical development activities, including on the timing of enrollment of our clinical trials; the timing of and our ability to obtain and maintain regulatory approvals;

our ability to obtain regulatory approval for, and commercialize, pegzilarginase, and recognize milestone and royalty payments from our licensing and supply agreement with Immedica; the potential for expedited development and review of

pegzilarginase as a result of its Breakthrough Therapy designation; the potential addressable markets of our product candidates; the rate and degree of market acceptance and clinical utility of our product candidates; the size and growth potential

of the markets for our product candidates, including the estimated treatment candidates for our product candidates, and our ability to serve those markets; our commercialization, marketing and manufacturing capabilities and strategy; future

agreements with third parties in connection with the potential commercialization of our product candidates; our expectations regarding our ability to obtain and maintain intellectual property protection; our dependence on third party manufacturers;

our ability to develop our own commercial manufacturing facility; the success of competing therapies that are or may become available; our ability to attract and retain key scientific or management personnel; our ability to identify additional

product candidates with significant commercial potential consistent with our commercial objectives; and our estimates regarding expenses, future revenue, capital requirements and needs for additional financing. Moreover, we operate in a very

competitive and rapidly changing environment, and new risks may emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or

combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed

herein may not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements. Further information on these and other factors that could affect these forward-looking statements is

contained in our most recent Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (SEC) and other reports filed by the SEC. You should not rely upon forward-looking statements as predictions of future events. Although

our management believes that the expectations reflected in our forward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances described in the forward-looking

statements will be achieved or occur. We undertake no obligation to publicly update any forward-looking statements, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or

Our Mission is to Change Lives by

Bringing Innovative Therapies to Underserved Rare Disease Communities Innovative enzyme engineering platform leading to differentiated product profiles Metabolic disease expertise creates complementary opportunities Pioneering Bold Science Focused

on disease modifying therapies with the potential to change the lives of patients and their families Strong engagement with patient communities to develop products that meet their needs Delivering Groundbreaking Medicines Novel approaches to

unconventional targets using human enzymes High unmet need and limited competition drive significant commercial opportunity Redefining the Possible 2023 Aeglea BioTherapeutics

Program Research Phase 1/2 Phase 3

Regulatory Review Addressable Market Geographic Rights Pegtarviliase Homocystinuria ~25,000 Patients1 Worldwide rights Pegzilarginase Arginase 1 Deficiency >2,500 Patients2 Retain rights outside of Europe and Middle East3 Preclinical Programs

Including Cystinuria Cystinuria Worldwide rights Aeglea's Human Enzyme Platform for Rare Metabolic Diseases 1 ~25,000 represents estimated treatment candidates of Classical Homocystinuria in 38 global addressable markets based on results of

U.S. ICD-10 claims analysis extrapolated to global markets; all figures rounded. Sellos-Moura et al 2020 2 Catsburg C et al 2022 ; Diez-Fernandez et al. Mutations and common variants in the human arginase 1 (ARG1) gene: impact on patients,

diagnostics and protein structure considerations. Hum Mutat. 2018 Aug;39(8):1029-10502 3 Ex-U.S. license and supply agreement with Immedica to commercialize pegzilarginase in Europe and certain countries in the Middle East (European Economic

Area, United Kingdom, Switzerland, Andorra, Monaco, San Marino, Vatican City, Turkey, Saudi Arabia, United Arab Emirates, Qatar, Kuwait, Bahrain and Oman) 4 Marketing Authorisation Application (MAA) validated by the European Medicines Agency (EMA)

and currently under review; Company in dialogue with the U.S. Food and Drug Administration following Refusal to File Letter MAA Validated by EMA4 2023 Aeglea BioTherapeutics

Highlights and Upcoming Milestones

Pegtarviliase in Homocystinuria: Currently dosing in cohort 3 at 1.35 mg/kg once weekly in Phase 1/2 clinical trial Enrollment in cohort 3 ongoing Pegzilarginase in ARG1-D: MAA under review with EMA, potential approval in the second half of 2023

Continuing to engage with FDA to identify potential path to BLA resubmission Corporate: Jeff Goldberg appointed CEO in November 2022 - highly experienced executive with strong operational and rare disease background $75.2 million in cash as of

September 30, 2022; projected runway into fourth quarter of 2023 2023 Aeglea BioTherapeutics

Pegtarviliase - Potential

Best-in-Class Treatment for Homocystinuria

Classical Homocystinuria (HCU)

Classical Homocystinuria: A Rare Metabolic Disorder With Serious and Potentially Deadly Complications Also known as cystathionine beta synthase (CBS) deficiency, Classical Homocystinuria is a serious and progressive metabolic disorder characterized

by elevated levels of the amino acid homocysteine. There are no approved treatments that address the underlying driver of disease - high homocysteine levels Toxic levels of homocysteine can lead to sudden catastrophic events, including death

Manifestations can occur in early childhood and worsen over time Serious Disease Complications Eyes Lens dislocation, glaucoma, severe near-sightedness Nervous System Intellectual and developmental delays, behavioral abnormalities, seizures Vascular

Life-threatening thrombotic events, heart attack, stroke Skeletal Long bone (Marfanoid) features, skeletal deformities, osteoporosis 2023 Aeglea BioTherapeutics

With persistently high total

homocysteine levels, patients remain at risk for serious and life-threatening complications Compliance with severe dietary restrictions and amino acid supplementation is extremely challenging and represents a lifelong burden Vitamin B6 is largely

ineffective for the majority of patients Betaine can be associated with both safety and tolerability issues such as hypermethioninemia, nausea, gastrointestinal distress, and body odor Patients with Classical HCU Live With Both Disease and Treatment

Burden "To get the family to cope with a very difficult life, and to have them compliant for life is a very big challenge." - EU Key Opinion Leader "For patients with Classical Homocystinuria, [the biggest challenge] would

be compliance with diet." - U.S. Key Opinion Leader One patient's daily protein supplement, which is only one portion of his treatment regimen 2023 Aeglea BioTherapeutics

Classical HCU: A Sizeable Patient

Population at Serious Risk of Severe Complications Over 80% of patients are unable to achieve total homocysteine levels <50 M with B6 alone This translates into an estimated ~25,000 treatment candidates in global addressable markets,1

approximately 8,500 of whom are in the U.S., EU4, and UK Average Age of Diagnosis 2 1 Data on file. Adapted from Sellos-Moura et al 2020. 2 Kozich, Sokolova, Morris, et al. 2021. 3 Mudd, Skovby et al. 1985. And Often Occurs After Severe

Complications2 Although Non-Responders and Partial Responders are generally diagnosed earlier in life, that diagnosis typically occurs several years following presentation of initial symptoms At time of diagnosis: 79% Non-Responders and Partial

Responders have experienced a lens dislocation 29% Non-Responders and Partial Responders have experienced a thromboembolic event 7.0 14.0 21.5 36.0 ER FR PR NR Age of Dx B6 Status Classical HCU by B6 Responsiveness2 2023 Aeglea

Pegtarviliase Mechanism Engineered

Cystathionine -Lyase (CGL) enzyme mutated to change its native substrate specificity from cystathionine to both homocysteine and its dimer Concentration gradient drives homocysteine out of tissue and into plasma Equilibrium in plasma favors dimer

over monomer Flux enables further metabolism of both monomer and dimer Pegtarviliase: An Innovative Enzyme Approach to Lowering Homocysteine 1Mudd, Skovby et al. 1985, Al-Dewik, Ali et al. 2019; 2Mudd, Skovby et al. 1985, Wilcken and Wilcken 1997,

Yap and Naughten 1998 Therapeutic Rationale Elevated levels of plasma homocysteine increase risk for disease manifestations1 Reduction of plasma homocysteine has been correlated with reduced risk of developing disease manifestations2 Generally

accepted aim of treatment is to lower the plasma homocysteine concentration below certain thresholds Depiction of Normal and Therapeutic Metabolism 2023 Aeglea BioTherapeutics

Experimental Design: 10-day old CBS

knockout mice were dosed with pegtarviliase twice per week for 5 weeks to ensure they were of a sufficient size Prior to a single subcutaneous dose of pegtarviliase, there was a two-week wash out To ensure accurate total homocysteine assessment, an

inhibitor of pegtarviliase was used in the collection tube to block metabolism of total homocysteine during sample processing2 Pegtarviliase Treatment Resulted in Dose-Dependent Response and Statistically Significant Lowering of Homocysteine in

Mouse Model Single Subcutaneous Dose in CBS Knockout Mouse Model1 * p < 0.05 by Manley Cox test Pegtarviliase (1.0 mg/kg, SC) Pegtarviliase (10.0 mg/kg, SC) Plasma tHcy ( M) Hours 1 Daige C. et al. Poster presented at ASHG 2020 Virtual

Meeting. 2 Thornloe K. et al. Poster presented at ACMG 2022 Meeting; tHcy = total homocysteine; SC = subcutaneous * * * * 2023 Aeglea BioTherapeutics

Preclinical Data Support Potential

Advantages of Pegtarviliase Pegtarviliase demonstrated significant survival benefit at substantially lower dose than competitor enzyme 1 Daige C. et al. Poster presented at ASHG 2020 Virtual Meeting. 2 Majtan T. et al., Life Sci. 2018; May

1;200:15-25. 3 Mice were maintained on betaine until weaning; tHcy = total homocysteine Pegtarviliase (10 mg/kg, BIW) Pegtarviliase (3 mg/kg, BIW) Pegtarviliase (1.0 mg/kg, BIW) Vehicle (BIW) Twice weekly (BIW) subcutaneous doses of

pegtarviliase in CBS knockout mouse model1,3 Significant survival benefit with pegtarviliase at total weekly dose of 2 mg/kg compared to a total weekly dose of 22.5 mg/kg reported for a competitor enzyme2 Pegtarviliase demonstrated pharmacological

effect on homocysteine levels in normal animals that is not seen with competitor enzyme Substantial decreases in homocysteine after single subcutaneous dose in toxicology studies with cynos (above) and rats (data not shown) Pharmacological effect in

normal animals dosed with pegtarviliase differentiated from reported data for a competitor enzyme2 Vehicle Pegtarviliase 2 mg/kg Pegtarviliase 6 mg/kg Pegtarviliase 20 mg/kg 2023 Aeglea BioTherapeutics

Phase 1/2 Clinical Trial to Generate

Proof-of-Concept and Path to Pivotal Trial Cohort 2 Cohort 3 PART 1 (Intravenous) PART 2 (Subcutaneous) Dose 0.45 mg/kg n = 4 Dose 1.35 mg/kg Currently enrolling Dose 0.15 mg/kg n = 3 Cohort 1 Cohort 5 (optional) Continuing to Enroll and Dose

Patients in Cohort 3 Cohort 4 (optional) Endpoints & Design Key Inclusion Criteria Safety and tolerability Pharmacokinetics Reduction in plasma homocysteine levels 4 once weekly doses Classical HCU diagnosis Plasma homocysteine

>80 M 12 years of age ( 18 years of age in U.S.) 2023 Aeglea BioTherapeutics

Data from cohorts 1-3 may be

sufficient for discussions with FDA on pivotal trial design Manufacturing at commercial scale Stable, high-concentration liquid formulation Orphan Disease and Rare Pediatric Disease designations allow for additional engagement with regulators

Advancing a Potential Best-in-Class Therapy for Classical HCU Patients Addressing an Unmet Need While Focusing on Patient Convenience Preparing for Rapid Transition to Phase 3 Pivotal Trial Efficacy: cohort 1 showed reduction in total homocysteine

levels in all patients Safety: large dosing window with acceptable adverse event profile Supported by toxicology study, Phase 1/2 data to date Potential for convenience of a single once-weekly injection at home 2023 Aeglea

Pegzilarginase for Arginase 1

The Progressive Impact of

Persistently High Plasma Arginine1-4 Arginase 1 Deficiency (ARG1-D) Disease Overview Infancy2-4,7,8 Initial 6-12 months may be uneventful May present with seizures, episodes of hyperammonemia: irritability, feeding difficulties, poor appetite,

nausea/vomiting, decreased alertness Toddlerhood (2-4 years) 2,3,7-9 Spasticity in lower limbs (toe walking) Seizures, avoidance of protein is common and intellectual disability Childhood (5-10 years) 2,3,5,6,9 Progressive spasticity and growth

impairment Declining neuromotor and intellectual capabilities Increasing dependence on walking aids Loss of mobility Decrease/loss of vocabulary/language Adolescence (11-17 years)2,3,5,10 Potential loss of ambulation and bowel/bladder control Severe

intellectual disability Adulthood (18+ years) 2,3,11,12 Continued decline with increasing disability that may result in early mortality 1 Diez-Fernandez C, et al. Hum Mutat. 2018;39:1029-1050. 2 Carvalho DR, et al. Pediatr Neurol. 2012;46:369-374. 3

Crombez EA, Cederbaum SD. Mol Genet Metab. 2005;84:243-251. 4 De Deyn PP, et al. Hyperargininemia: a treatable inborn error of metabolism. In: Guanidino Compounds in Biology and Medicine. London, UK: John Libbey Company Ltd.; 1997:53-69. 5 Prasad A,

et al. J Child Neurol. 1997;12:301-309. 6 Amayreh W, et al. Dev Med Child Neurol. 2014;56:1021-1024. 7 Scaglia F, Lee B. Am J Med Genet C Semin Med Genet. 2006;142C:113-120. 8 Sin YY, et al. J Mol Med (Berl). 2015;93:1287-1296. 9 Cai X, et al.

Medicine (Baltimore). 2018;97:e9880. 10 Schlune A, et al. J. Amino Acids. 2015;47:1751-1762. 11 Sun A, et al. Arginase deficiency. In: Adam MP, et al, eds. GeneReviews . Seattle, WA: University of Washington, Seattle; 2020. 12 Diaz GA, et al.

Poster presented at: 13th European Paediatric Neurology Society (EPNS) Congress; September 17-21, 2019; Athens, Greece. Poster P06-34. Current Standard of Care Focused on lowering plasma arginine levels and controlling hyperammonemia with: Severe

dietary protein restriction Amino acid supplementation Ammonia scavengers Ineffective at controlling plasma arginine levels Significant Unmet Need High arginine levels Severe and progressive disease with early mortality Easily diagnosed but often

missed due to lack of awareness No approved therapies to address high arginine levels ARG1-D is a serious, progressive disease with early mortality and high unmet medical need. It is caused by a mutation in the arginase 1 enzyme, resulting in

persistently high levels of arginine. 2023 Aeglea BioTherapeutics

Pegzilarginase Program Overview

Commercial Opportunity >2,500 patients in global addressable markets1 High unmet medical need No approved therapies to address high arginine levels Regulatory Designations U.S. Rare Pediatric Disease (PRV eligible) Breakthrough Therapy U.S.

Orphan Drug EU Orphan Drug Pegzilarginase is a novel recombinant human enzyme engineered to lower arginine levels Ongoing Discussions with FDA on Potential Paths to BLA Resubmission PEACE Phase 3 Clinical Trial First placebo-controlled trial ever

conducted in ARG1-D Pegzilarginase reduced arginine levels by 76.7%, normalized arginine levels in 90.5% of patients Positive trend in mobility measure Well-tolerated 31 patients enrolled in long-term extension study Phase 1/2 and Open-Label

Extension Trials 13 patients remain on therapy, duration from 2-4 years Arginine lowering was rapid and durable Improvements in functional measures sustained over time First Clinical Program Ever Conducted in ARG1-D 1 Catsburg C et al 2022; PRV =

priority review voucher 2023 Aeglea BioTherapeutics