Aeglea BioTherapeutics Reports Third Quarter 2022 Financial Results and Provides Program Updates

Interim Clinical Data from Phase 1/2 Trial of Pegtarviliase Expected in Fourth Quarter of 2022; Currently Dosing Cohort 3 at 1.35 mg/kg

MAA for Pegzilarginase for the Treatment of Arginase 1 Deficiency Accepted for Review by the EMA

$75.2 Million of Cash as of September 30, 2022; Runway into Fourth Quarter of 2023

AUSTIN, Texas, Nov. 3, 2022 /PRNewswire/ -- Aeglea BioTherapeutics, Inc. (NASDAQ:AGLE), a clinical-stage biotechnology company developing a new generation of human enzyme therapeutics as innovative solutions for rare metabolic diseases, today announced financial results for the third quarter ended September 30, 2022 and provided program updates.

"With our recent corporate restructuring we have prioritized our pegtarviliase program to optimize our resources and maximize Aeglea's success. We continue to advance our Phase 1/2 trial of pegtarviliase for Classical Homocystinuria with the ongoing enrollment of cohort 3 and look forward to sharing interim data from this trial before the end of the year," said Jim Kastenmayer, Ph. D., J.D., interim chief executive officer and general counsel of Aeglea. "While our primary focus is pegtarviliase, we are a multi-program company and are pleased that the Marketing Authorization Application for pegzilarginase for Arginase 1 Deficiency submitted by our valued partner Immedica is currently under review by the EMA for a potential approval next year. We view the progress in our portfolio as validation of what can be accomplished through our innovative human enzyme engineering platform and its potential to transform the lives of patients and families living with rare metabolic diseases."

Pegtarviliase in Homocystinuria

• Currently dosing Classical Homocystinuria patients in cohort 3 at 1.35 mg/kg once weekly via subcutaneous injection in the Phase 1/2 clinical trial.
• Plan to announce interim Phase 1/2 clinical data, including data from cohort 3, in the fourth quarter of 2022.
• Received a letter from the U.S. Food and Drug Administration (FDA) responding to a protocol amendment stating that patients aged younger than 18 years cannot currently be enrolled in the Phase 1/2 trial. The company believes the letter will have no impact on the timeline for the trial.
• Hosted a Key Opinion Leader (KOL) webinar discussing Classical Homocystinuria and providing an overview of the pegtarviliase program.

Pegzilarginase in Arginase 1 Deficiency

• Marketing Authorization Application (MAA) was submitted by Immedica, Aeglea's commercialization partner in Europe and certain countries in the Middle East, and validated by the European Medicines Agency (EMA). The MAA is currently under review by the EMA.
• Actively engaged with the FDA to identify a viable regulatory approach and path to the resubmission of the Biologics License Application (BLA).
• Presented efficacy and safety data from the PEACE Phase 3 clinical trial at the Society for the Study of Inborn Errors of Metabolism (SSIEM).

Corporate

• Announced a corporate restructuring in order to prioritize resources and focus on the pegtarviliase program while reducing expenses.
• Jim Kastenmayer, Ph.D., J.D, the company's general counsel, was appointed interim chief executive officer. A search for a permanent chief executive officer is currently underway.

• Piper Sandler 34^th Annual Healthcare Conference, November 29-December 1, 2022
• 5^th Annual Evercore ISI HealthCONx Conference, November 29-December 1, 2022
• LifeSci Advisors Corporate Access Event, held during the JP Morgan 41^st Annual Healthcare Meeting, January 9-12, 2023

As of September 30, 2022, Aeglea had available cash, cash equivalents, marketable securities and restricted cash of $75.2 million. The company expects its cash, cash equivalents and marketable securities will enable it to fund its operating expenses and capital expenditure requirements into the fourth quarter of 2023.

Aeglea recognized development fee revenues of $0.2 million in the third quarter of 2022 as a result of its license and supply agreement with Immedica for the commercial rights to pegzilarginase in certain territories outside the U.S. The revenue was related to the PEACE Phase 3 trial and BLA package. In the third quarter of 2021, Aeglea recognized $1.4 million of license and development revenue in connection with the Immedica license and supply agreement.

Research and development expenses totaled $12.0 million for the third quarter of 2022 and $14.9 million for the third quarter of 2021. The decrease was primarily due to a reduction in expenses associated with the PEACE Phase 3 clinical trial and expenses associated with good manufacturing practice readiness for pegtarviliase.

General and administrative expenses totaled $7.0 million for the third quarter of 2022 and $6.8 million for the third quarter of 2021. This increase was due to compensation and other personnel expenses associated with severance pay and benefits which was partially offset by a decrease in commercial expenses.

Net loss totaled $18.2 million and $20.3 million for the third quarter of 2022 and 2021, respectively, with non-cash stock compensation expense of $1.6 million and $2.1 million for the third quarter of 2022 and 2021, respectively.

Pegtarviliase (formerly AGLE-177) is a novel recombinant human enzyme, which is engineered to degrade the amino acid homocysteine and its dimer. Pegtarviliase is currently being studied in a Phase 1/2 clinical trial for the treatment of patients with Classical Homocystinuria, a rare inherited disorder of methionine metabolism that results in elevated levels of total homocysteine. Homocysteine accumulation plays a key role in multiple progressive and serious disease-related complications, including thromboembolic vascular events, skeletal abnormalities (including severe osteoporosis), developmental delay, intellectual disability, lens dislocation and severe near sightedness. In preclinical studies, pegtarviliase improved important disease-related abnormalities and survival in a mouse model of Homocystinuria. Pegtarviliase has received both U.S. and EU Orphan Drug Designation as well as U.S. Rare Pediatric Disease Designation.

Pegzilarginase is a novel recombinant human enzyme engineered to degrade the amino acid arginine and has been shown to rapidly and sustainably lower levels of the amino acid arginine in plasma. Aeglea is developing pegzilarginase for the treatment of people with Arginase 1 Deficiency (ARG1-D), a rare debilitating and progressive disease characterized by the accumulation of arginine. ARG1-D presents in early childhood and patients experience spasticity, seizures, developmental delay, intellectual disability and early mortality. The PEACE Phase 3 clinical trial met its primary endpoint with a 76.7% reduction in mean plasma arginine compared to placebo. Additionally, 90.5% of pegzilarginase treated patients achieved normal plasma arginine levels. The arginine lowering was accompanied by a positive trend in Gross Motor Function Measure Part E, a measure of patient mobility. Pegzilarginase has received multiple regulatory designations, including Rare Pediatric Disease, Breakthrough Therapy, Fast Track and Orphan Drug designations from the U.S. Food and Drug Administration as well as Orphan Drug Designation from the European Medicines Agency.

Aeglea BioTherapeutics is a clinical-stage biotechnology company redefining the potential of human enzyme therapeutics to benefit people with rare metabolic diseases with limited treatment options. Aeglea is investigating pegtarviliase in an ongoing Phase 1/2 clinical trial for the treatment of Classical Homocystinuria. Pegtarviliase has been granted Rare Pediatric Disease Designation. Aeglea's other clinical program, pegzilarginase, achieved the primary endpoint of arginine reduction in the PEACE Phase 3 clinical trial and has received both Rare Pediatric Disease and Breakthrough Therapy Designations. The Marketing Authorization Application for pegzilarginase is currently under review with the European Medicines Agency. Aeglea has an active discovery platform focused on engineering small changes in human enzymes to have a big impact on the lives of patients and their families. For more information, please visit https://aeglea.com.

This press release contains "forward-looking" statements within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by words such as: "anticipate," "intend," "plan," "goal," "seek," "believe," "project," "estimate," "expect," "strategy," "future," "likely," "may," "should," "will" and similar references to future periods. These statements are subject to numerous risks and uncertainties that could cause actual results to differ materially from what we expect. Examples of forward-looking statements include, among others, statements we make regarding the timing of announcements and updates relating to our clinical trials and related data, including the clinical data for our Phase 1/2 trial of pegtarviliase in Classical Homocystinuria, the timing and success of our clinical trials and related data, the timing and expectations for regulatory submissions and approvals, including the MAA for pegzilarginase in Europe, our ability to obtain regulatory approval for, and commercialize, pegzilarginase, recognize milestone and royalty payments from our agreement with Immedica, our ability to enroll patients into our clinical trials, the expected impact of the COVID-19 pandemic on our operations and clinical trials, success in our collaborations, the length of time that we believe our existing cash resources will fund operations, the potential addressable markets of our product candidates and the potential therapeutic benefits and economic value of our lead product candidate or other product candidates. Further information on potential risk factors that could affect our business and its financial results are detailed in our most recent Quarterly Report on Form 10-Q for the quarter ended September 30, 2022 filed with the Securities and Exchange Commission (SEC), and our other reports as filed with the SEC. We undertake no obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise.

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SOURCE Aeglea BioTherapeutics, Inc.