Forward Looking Statements 2023 Aeglea BioTherapeutics This presentation by Aeglea BioTherapeutics, Inc. ("we", "our" or "us") contains "forward-looking" statements within the meaning of the Private Securities Litigation

Redefining the Possible. Human Enzyme

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

Forward Looking Statements 2023

Aeglea BioTherapeutics This presentation by Aeglea BioTherapeutics, Inc. ("we", "our" or "us") contains "forward-looking" statements within the meaning of the Private Securities Litigation Reform Act

of 1995 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, our ability to identify, assess and execute a strategic transaction or realize any value from our existing assets and the timing thereof,

including updates concerning the process to explore strategic alternatives, our current and future clinical and preclinical development activities, timing and success of our 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 risk that we may not execute our planned exploration and evaluation of strategic alternatives; the availability of

suitable third parties with which to conduct contemplated strategic transactions; the risk that our restructuring costs and charges may be greater than anticipated or incurred in different periods than anticipated; the risk that our restructuring

efforts may adversely affect our internal programs and our ability to retain key personnel; the risk that our restructuring efforts may not generate their intended benefits to the extent or as quickly as anticipated; the risk that our restructuring

efforts may negatively impact our business operations and reputation; the success, cost and timing of our product candidate development activities and 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 in Classical Homocystinuria, the MAA for pegzilarginase in Europe, and potential resubmission of a BLA for pegzilarginase in the U.S.; 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 expected impact of macroeconomic conditions, including inflation, increasing interest rates and volatile market conditions

(such as recent or potential bank failures) on our operations and clinical development activities; 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 under our licensing and supply agreement with Immedica; the potential for expedited development and review of pegtarviliase and pegzilarginase as a result of their regulatory designations;

the number of possible treatment candidates in 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, 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; and our estimates regarding expenses, future revenue, capital requirements, the length of time that we believe our existing cash

resources will fund operations, 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. Unless required by law, 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 otherwise. Certain information contained in this presentation relates to or is based on

studies, publications, surveys and other data obtained from third-party sources and our own internal estimates and research. While we believe these third-party sources to be reliable as of the date of this presentation, we have not independently

verified, and makes no representation as to the adequacy, fairness, accuracy or completeness of, any information obtained from third-party sources. In addition, all of the market data included in this presentation involves a number of assumptions

and limitations, and there can be no guarantee as to the accuracy or reliability of such assumptions. Finally, while we believe our own internal research is reliable, such research has not been verified by any independent source. You are cautioned

not to give undue weight to any such information, projections and estimates.

Recent Developments and Upcoming

Milestones Pegtarviliase in Homocystinuria: Announced interim results from Cohorts 1-3 in April 2023 Data from Cohorts 1 and 2 suggested a dose-dependent treatment effect Cohort 3 data confounded by presence of anti-drug antibodies (ADAs) and does

not support interactions with regulatory authorities on next steps at this time Pegzilarginase in Arginase 1 Deficiency: MAA under review with EMA, potential decision on approval in late 2023 Partnered in Europe and certain countries in Middle East;

rest of world rights remain available Corporate: Workforce reduction announced in April 2023; approximately 10 employees retained Exploring strategic alternatives with the goal of maximizing shareholder value Estimated $39.8 million in cash and cash

equivalents, marketable securities and restricted cash as of March 31, 20231 2023 Aeglea BioTherapeutics 1 Because our condensed consolidated financial statements for the quarter ended March 31, 2023 have not been finalized, this preliminary

estimate of cash and cash equivalents, marketable securities and restricted cash as of March 31, 2023 is subject to change. Our actual cash and cash equivalents, marketable securities and restricted cash as of March 31, 2023 may differ materially

from this preliminary estimate.

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 Therapies for Rare Metabolic Diseases 1 ~25,000 represents estimated treatment candidates in 38 addressable markets of Classical Homocystinuria based on results of U.S.

ICD-10 claims analysis extrapolated to global markets; all figures rounded. Estimates also based on internal assumptions and data from 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 several

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 Market 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

Pegtarviliase - Potential

Treatment for Homocystinuria

Classical Homocystinuria (HCU)

Classical Homocystinuria: A Rare Metabolic Disorder With Serious and Potentially Deadly Complications ystathionine beta synthase (CBS) deficiency, Classical Homocystinuria is a serious and progressive metabolic disorder characterized by elevated

amino acid homocysteine. 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 1Betaine, approved by the FDA in 1996, can lower homocysteine levels in the blood through remethylation to methionine

but does not metabolize homocysteine and clear it from the body

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 at lowering tHcy to guidance levels 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 tHcy = total

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, the definition of B6 responsiveness 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 Complications2,3 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 BioTherapeutics

Pegtarviliase: An Innovative Enzyme

Approach to Lowering Homocysteine 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 tissues and into plasma Equilibrium in plasma favors dimer over monomer Flux enables further metabolism of both monomer and dimer 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 total homocysteine increase risk for disease manifestations1 Reduction of plasma total homocysteine has been correlated with reduced risk of developing disease

manifestations2 Generally accepted aim of treatment is to lower the plasma total homocysteine concentration below certain thresholds to reduce risk of disease-related events Depiction of Normal and Therapeutic Metabolism 2023 Aeglea

Phase 1/2 Clinical Trial Design

Cohort 2 Cohort 3 PART 1 (Intravenous) PART 2 (Subcutaneous) Dose 0.45 mg/kg n = 4 Dose 1.35 mg/kg n = 4 Dose 0.15 mg/kg n = 3 Cohort 1 Cohort 5 Completed Dosing in Cohort 3 Endpoints & Design Key Inclusion Criteria Safety and tolerability

Pharmacokinetics Reduction in plasma homocysteine levels 4 once weekly doses HCU diagnosis Plasma homocysteine 50 M with documented history of plasma homocysteine 80 M 12 years of age ( 18 years of age in U.S.

and certain Australian sites) 2023 Aeglea BioTherapeutics Cohort 4 Optional Cohorts Within Protocol

2023 Aeglea BioTherapeutics.

External Interim Results from Phase 1/2 Clinical Trial: Lowering of Homocysteine Data from Cohorts 1 and 2 showed that treatment with pegtarviliase lowered total homocysteine levels when compared to baseline values Cohort 3 data confounded by

presence of anti-drug antibodies (ADAs) Potential to dose through ADAs with longer treatment duration and/or higher dose Cohort 1 (0.15 mg/kg) n=3 Cohort 3 (1.35 mg/kg) n=4* Cohort 2 (0.45 mg/kg) n=4 Percent Change of Homocysteine from Baseline

After 4 Once-Weekly Treatments *n=3 for 7 days post dose, due to missing data point from one of four evaluable patients

Interim Results from Phase 1/2

Clinical Trial: Safety Summary 2023 Aeglea BioTherapeutics. Confidential Information Adverse Events Participants N=13 Any treatment-emergent AE 13 (100%) AE leading to discontinuation 0 AE leading to dose reduction 0 AE of special interest:

HSR ISR 2 (15.3%) 10 (76.9%) Serious AEs Fatal Related 1 (7.7%) 0 0 Adverse events (AEs) associated with subcutaneous administration Majority of AE were Grade 1/2 injection site reactions (ISR) and hypersensitivity reactions (HSR) Managed with

antihistamines, steroids Pegtarviliase was Well Tolerated with Adverse Events Primarily Associated with Subcutaneous Route of Administration

Efficacy Data from Phase 1/2

clinical trial indicated pegtarviliase is capable of lowering homocysteine levels Results from cohort 3 did not show consistent homocysteine lowering, likely due to the presence of ADAs ADAs frequently seen with other pegylated enzyme therapies;

potential to dose through pharmacological impact Pegtarviliase Program Summary Safety Adverse events have been mild to moderate in data gathered to date Toxicology data indicates a large dosing window and potential to continue dose escalation

Manufacturing Stable, high-concentration liquid formulation Regulatory Orphan Disease, Fast Track and Rare Pediatric Disease designations for Homocystinuria 2023 Aeglea BioTherapeutics Additional cohorts could be used to explore higher doses,

longer dosing duration, and the potential to dose through the impact of ADAs

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