Aeglea BioTherapeutics, Inc. (NASDAQ:AGLE), a clinical-stage biotechnology company developing a new generation of human enzyme therapeutics to benefit people with rare metabolic diseases, today announced that a Marketing Authorization Application (MAA) for pegzilarginase for the treatment of Arginase 1 Deficiency (ARG1-D) has been submitted to and successfully validated by the European Medicines Agency (EMA). The MAA was submitted by Immedica Pharma AB, Aeglea's commercialization partner in Europe and the Middle East.

Pegzilarginase is a novel, recombinant human arginase 1 enzyme that in clinical trials has been shown to normalize the elevated levels of the amino acid arginine in patients with ARG1-D, a rare, progressive disease characterized by high levels of arginine. People living with ARG1-D experience severe spasticity-related mobility limitations, seizures, developmental delay, intellectual disability, and early mortality.

"For progressive diseases like ARG1-D, every day that passes without an approved therapy increases the disease burden and worsens the outcome for patients and their families. If approved, we believe pegzilarginase has the potential to benefit these families," said Anthony G. Quinn, M.B., Ch.B., Ph.D., president and chief executive officer of Aeglea. "We are thrilled with the progress being made with the validation of the MAA and look forward to continuing to work with and support our partner Immedica throughout the EMA review process."

Dr. Quinn continued, "I would like to thank all the patients, families, investigators, staff and advocates who participated in our clinical trials and helped in the advancement of pegzilarginase, potentially the first health authority-approved treatment to address the underlying driver of ARG1-D, elevated arginine levels."

Immedica's MAA submission includes data from multiple clinical studies in ARG1-D, including the double-blind, placebo-controlled PEACE Phase 3 study and its ongoing long-term extension, a Phase 1/2 clinical trial and an open-label extension study. Results from these trials demonstrate that pegzilarginase is able to rapidly and sustainably lower arginine levels and showed improvements in measures of mobility. In the PEACE study, most treatment-emergent adverse events were mild or moderate in severity and there were no discontinuations due to treatment-emergent adverse events. The EMA has granted pegzilarginase Orphan Drug 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. Aeglea's Phase 1/2 and Phase 2 Open-Label Extension (OLE) data for pegzilarginase in patients with ARG1-D demonstrated clinical improvements and sustained lowering of plasma arginine. 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. 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. Aeglea also has an ongoing Phase 1/2 clinical trial of AGLE-177 for the treatment of Homocystinuria. AGLE-177 has been granted Rare Pediatric Disease Designation. 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 http://aeglea.com.

Safe Harbor / Forward Looking Statements

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 our ability to obtain regulatory approval for, and commercialize, pegzilarginase, recognize milestone and royalty payments from our agreement with Immedica, 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, timing and results of meetings with regulators, the timing of announcements and updates relating to our clinical trials and related data, 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 June 30, 2022 filed with the Securities and Exchange Commission (SEC), and 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.