Myrtelle Announces Presentation of Positive 6-month Post-Treatment Data in Its First-in-Human Clinical Study of rAAV-Olig001-ASPA Gene Therapy in Canavan Disease at the American Society of Gene and Cell Therapy 26th Annual Meeting

Myrtelle Inc. ("Myrtelle" or the "Company"), a gene therapy company focused on developing transformative treatments for neurodegenerative diseases, today announced that updated positive data in its open-label Phase 1/2 First-in-Human (FIH) clinical trial for Canavan disease using the Company's recombinant adeno-associated virus (rAAV) vector-based investigational gene therapy will be presented at the upcoming American Society of Gene and Cell Therapy (ASGCT) 26^th Annual Meeting, taking place in Los Angeles May 16-20, 2023.

Christopher Janson, M.D., Principal Investigator on Myrtelle's Canavan Disease Gene Therapy Trial and Assistant Professor of Neurology and Neuroscience at Wright State University Boonshoft School of Medicine and Director of Human Gene Therapy Center at Wright State Neuroscience Institute in Dayton, Ohio, will deliver a presentation entitled "Phase 1/2 First-in-Human Gene Therapy Clinical Trial ?in Patients with Canavan Disease" on Friday, May 19, 2023.

Clinical measurements of motor and cognitive function using validated assessment scales demonstrate mean absolute and percent improvements across multiple domains. Improvements in multiple anatomic and biomarker measurements by magnetic resonance imaging (MRI) and spectroscopy (MRS) have also been observed. These improvements in treated patients contrast the deterioration in untreated age-matched CD patients in Myrtelle's natural history data set. No serious drug-related adverse events have been observed to date.

Myrtelle's FIH trial utilizes the Company's proprietary rAAV vector to directly target oligodendrocytes, the brain cells affected in CD that are responsible for producing myelin ? the insulating material that enables proper neuronal function. In CD, normal brain development is impaired due to a mutation in the ASPA gene that encodes the enzyme aspartoacylase. The deficiency of aspartoacylase enzyme results in multiple biochemical and anatomic changes, including the inability to metabolize the neurochemical N-acetylaspartate (NAA). The lack of normal aspartoacylase expression negatively impacts brain bioenergetics and development, including myelin production. The oligodendrocyte-targeting rAAV vector-based gene therapy is intended to restore ASPA function and hence the metabolism of NAA and brain development in patients with CD.

"The functional, anatomic and biomarker data observed in patients treated in Myrtelle's Phase 1/2 gene therapy study using its oligodendrocyte-targeting AAV vector are encouraging and suggest the gene therapy is having its intended effect," said Dr. Janson. "We look forward to sharing details at the upcoming ASGCT conference."

Session: Gene Therapies Targeting Oligodendrocytes

Date/Time: Friday May 19, 2023, 12pm ? 1:30 pm PT

Location: Room 501

ABOUT MYRTELLE

Myrtelle Inc. is a gene therapy company focused on developing transformative treatments for neurodegenerative diseases. The company has a proprietary platform, intellectual property, and portfolio of programs and technologies supporting innovative gene therapy approaches for neurodegenerative diseases. Myrtelle has an exclusive worldwide licensing agreement with Pfizer Inc. for its Canavan disease program. For more information, please visit the Company's website at: www.myrtellegtx.com.

ABOUT CANAVAN DISEASE

Canavan disease (CD) is a fatal childhood genetic brain disease caused by mutations in the ASPA gene (ASPA) which prevent the normal expression of aspartoacylase, a critical enzyme produced in oligodendrocytes that breaks down the neurochemical N-acetylaspartate (NAA). When not properly metabolized by oligodendrocytes, NAA accumulates in the brain. The lack of normal aspartoacylase expression negatively impacts brain bioenergetics and development, including myelin production. Patients with CD are impacted at birth but may appear normal until several months old when symptoms begin to develop. Poor head control, abnormally large head size, difficulty in eye tracking, excessive irritability, severely diminished muscle tone, and delays in reaching motor milestones, such as rolling, sitting, and walking, are the typical initial manifestations of CD. As the disease progresses, seizures, spasticity, difficulties in swallowing, and overall muscle deterioration emerge with most affected children developing life-threatening complications by approximately 10 years of age. Currently, there are no cures for CD, and only palliative treatments are available.

More information on Myrtelle's clinical trial in Canavan disease can be found on https://clinicaltrials.gov/ under the identifier NCT04833907 or by emailing [email protected].

Forward-Looking Statements

This press release contains forward-looking statements. Words such as "may," "believe," "will," "expect," "plan," "anticipate," "estimate," "intend" and similar expressions (as well as other words or expressions referencing future events, conditions, or circumstances) are intended to identify forward-looking statements. Forward-looking statements are based upon current estimates and assumptions and include statements regarding the functional, anatomic and biomarker data observed in patients treated in Myrtelle's Phase 1/2 gene therapy study using its oligodendrocyte-targeting AAV vector suggesting the gene therapy is having its intended effect. While Myrtelle believes these forward-looking statements are reasonable, undue reliance should not be placed on any such forward-looking statements, which are based on information available to us on the date of this release. These forward-looking statements are subject to various risks and uncertainties, many of which are difficult to predict, that could cause actual results to differ materially from current expectations and assumptions from those set forth or implied by any forward-looking statements. Important factors that could cause actual results to differ materially from current expectations include, among others, Myrtelle's program demonstrating safety and efficacy, as well as future results that are consistent with prior results, the ability to generate the data needed for further development of this novel gene therapy in the patients with CD, and the ability to continue its clinical trials and to complete them on time and achieve the desired results. All forward-looking statements are based on Myrtelle's expectations and assumptions as of the date of this press release. Actual results may differ materially from these forward-looking statements. Except as required by law, Myrtelle expressly disclaims any responsibility to update any forward-looking statement contained herein, whether as a result of new information, future events, or otherwise.