Wakefield, Mass., Wednesday, May 31, 2023 – 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 (CD) using the Company’s recombinant adeno-associated virus (rAAV) vector-based investigational gene therapy will be presented at the National Tay-Sachs and Allied Diseases Annual Family Conference, taking place in Reston, Virginia June 1-4, 2023. Olga Flamini, MD, PhD, Medical Director at Myrtelle, will deliver a presentation on Friday, June 2, 2023.

Clinical measurements of motor, language, and cognitive function using validated assessment scales that demonstrate mean absolute and percent improvements across multiple domains will be presented, as well as improvements in anatomic and biomarker measurementsx observed in magnetic resonance imaging (MRI) and spectroscopy (MRS). In particular, patients show mean improvements across multiple subscales of the Gross Motor Function Measure-88 (GMFM-88) and Mullen Scales of Early Learning (MSEL), including first-time achievement of milestones such as sitting, standing with support, and taking steps with assistance, improvement in language ability (verbal and receptive language domains) and improvement in cognitive ability (visual reception daomain). Supporting the functional gains, the patient group also shows mean improvements in MRI-based measures of myelin, white matter, grey matter and CSF volumes, along with reductions in NAA levels. Several changes represent statistically significant improvements from baseline over six months post treatment. 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. Under the clinical protocol, patients were treated with a single dose of 3.7 x 1013 vector copies, administered by intraventricular delivery to directly target oligodendrocytes of the brain, where ASPA activity needs to be restored. This direct delivery potentially mitigates certain side effects associated with IV administration such as immune responses, complement activation, increases in liver enzymes, or other off-target complications, thereby avoiding the need of high dose steroid administration. Based on the positive results to date, Myrtelle anticipates meeting with regulatory authorities in the near-term to discuss remaining requirements for product approval. Accordingly, the current study is closed to enrollment, as posted on https://clinicaltrials.gov/ under the identifier NCT04833907.

“We look forward to sharing encouraging updates with the NTSAD community from Myrtelle’s Phase 1/2 gene therapy study using its oligodendrocyte-targeting AAV vector,” said Dr. Flamini. “Connecting with patients and caregivers allows us to incorporate the patient voice into our drug development activities.”

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 PatientAdvocacy@MyrtelleGTX.com.

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 direct delivery potentially mitigating certain side effects associated with IV administration such as immune responses, complement activation, increases in liver enzymes, or other off-target complications, thereby avoiding the need of high dose steroid administration, meeting with regulatory authorities in the near-term to discuss remaining requirements for product approval. 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.

Media Contact:

Jordana Holovach

Head of Communications and Community

Myrtelle Inc.

781-621-2797 Ext. 102

jholovach@myrtellegtx.com