Stealth BioTherapeutics Announces Positive End-of-Phase 2 Meeting with FDA on the Development of Elamipretide in Patients with Dry Age-related Macular Degeneration

• Elamipretide showed favorable effect on photoreceptor integrity (ellipsoid zone attenuation) and visual function (low light - best corrected visual acuity)
• Positive end-of-phase 2 FDA meeting confirmed ellipsoid zone attenuation as an approvable clinical trial endpoint in dry AMD

NEEDHAM, Mass., June 12, 2023 /PRNewswire/ -- Stealth BioTherapeutics Inc. (the “Company” or “Stealth BioTherapeutics”), a clinical-stage biotechnology company focused on the discovery, development, and commercialization of novel therapies for diseases involving mitochondrial dysfunction, today announced the successful and favorable outcomes of an end-of-phase 2 meeting with the U.S. Food and Drug Administration (FDA) for elamipretide, its lead drug candidate for the treatment of dry age-related macular degeneration (AMD).

The end-of-phase 2 meeting scope included all aspects of the elamipretide development plan and clinical data, including the correlation analyses between anatomical (total ellipsoid zone attenuation) and functional (low light-best corrected visual acuity (LL BCVA)) outcomes. The analyses demonstrated that patients with a greater degree of ellipsoid zone (EZ) integrity showed a better functional response in elamipretide-treated patients.¹ These findings support that EZ attenuation is likely to predict disease progression and suggest clinical and functional benefit of elamipretide in dry AMD. Following the meeting, the FDA’s minutes confirmed EZ attenuation as an approvable endpoint in dry AMD. Results from the ReCLAIM-2 trial in dry AMD were recently presented by Dr. Peter K. Kaiser, from the Cole Eye Institute at the Cleveland Clinic, at the Clinical Trials at the Summit Meeting on June 10, 2023, in Park City, Utah.

“Since photoreceptor-mediated vision loss is of utmost importance to patients suffering from dry AMD, we are thrilled that our mitochondria-targeted investigational drug showed a favorable effect on visual function (≥2-line improvement in LL-BCVA) and photoreceptor integrity (43% reduction in total EZ attenuation),” said Reenie McCarthy, Chief Executive Officer of Stealth BioTherapeutics. “FDA’s confirmation that EZ attenuation is an approvable marker of photoreceptor loss is a huge step forward for our ophthalmology program and, we hope, patients.”

“There is a need for measures of dry AMD progression that occur earlier than the development of geographic atrophy or visual acuity loss as these outcomes are limited due to the relatively slow progression of the disease” said Dr. Kaiser, of the Cleveland Clinic. “With the identification of agents with novel mechanisms of action, such as mitochondrial-targeted elamipretide, we are able to identify very interesting changes in our imaging tests that can potentially help guide registration studies.”

About Dry AMD
Dry AMD is a leading cause of blindness impacting more than 5 million people worldwide which can severely impair visual function, independence, and quality of life. Dry AMD is a progressive retinal disease in which the photoreceptors, which are specialized neurons found in the retina that convert light into electrical signals required for normal visual function, suffer progressive damage and death, leading to progressive loss of vision. One of the earliest signs of photoreceptor dysfunction is progressive damage to, or attenuation of, the ellipsoid zone (EZ), which is a mitochondrial rich layer of the photoreceptors. EZ attenuation has been shown to precede and predict visual dysfunction in dry AMD and other retinal diseases.

About Elamipretide and Dry AMD
Elamipretide is an investigational mitochondrial protective agent that has been shown in preclinical studies to normalize mitochondrial structure and function and improve cell viability and organ function across a spectrum of disease models, including models of cardiovascular, renal, metabolic, skeletal muscle, neurodegenerative, and genetic mitochondrial disease. Elamipretide readily penetrates cell membranes and transiently localizes to the inner membrane of the mitochondria where it interacts with cardiolipin. Elamipretide has been assessed in a phase 2, randomized, double-masked, placebo-controlled clinical study to evaluate the safety, efficacy, and pharmacokinetics of subcutaneous injections of elamipretide in subjects with dry AMD with geographic atrophy.

About Stealth
The Company is a clinical-stage biotechnology company focused on the discovery, development, and commercialization of novel therapies for diseases involving mitochondrial dysfunction. Mitochondria, found in nearly every cell in the body, are the body’s main source of energy production and are critical for normal organ function. Dysfunctional mitochondria characterize a number of rare genetic diseases and are involved in many common age-related diseases, typically involving organ systems with high energy demands such as the eye, the neuromuscular system, the heart and the brain. The Company believes that its lead product candidate, elamipretide, has the potential to treat ophthalmic diseases, such as dry AMD, rare neuromuscular disorders, such as primary mitochondrial myopathy, and rare cardiomyopathies, such as Barth syndrome. The Company has a deep pipeline of novel mitochondria-targeted compounds under evaluation as therapeutic product candidates.

Investor Relations
Kendall Investor Relations
Adam Bero, Ph.D.
abero@kendallir.com
IR@StealthBT.com

Media Relations
Anna Stallman Communications
Anna Stallman
anna@annacomms.com

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SOURCE Stealth BioTherapeutics Inc.