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Stealth BioTherapeutics Announces Positive Results for Elamipretide in Ophthalmic Conditions

April 30, 2019

BOSTON, April 30, 2019 /PRNewswire/ -- Stealth BioTherapeutics (NASDAQ: MITO), a clinical-stage biotechnology company focused on the discovery, development and commercialization of novel therapies for diseases involving mitochondrial dysfunction, recently presented positive results from its ophthalmic programs in dry age-related macular degeneration (AMD) and Leber's hereditary optic neuropathy (LHON). The data, which were presented at the Association for Research in Vision and Ophthalmology (ARVO) 2019 Annual Meeting, being held April 28May 2 in Vancouver, British Columbia, demonstrated significant improvements in visual function following treatment with elamipretide, an investigational drug, in its ReCLAIM study of patients with dry AMD and in the open-label portion of its ReSIGHT study of patients with LHON.

Stealth BioTherapeutics Logo (PRNewsFoto/Stealth BioTherapeutics)

"People with dry AMD typically experience a progressive vision loss that interferes with day-to-day living and limits independence," said Dr. Scott Cousins, principal investigator and Professor of Ophthalmology and Director of the Duke University Center for Macular Diseases, who gave an oral presentation of the non-central geography cohort data at ARVO. "ReCLAIM provides preliminary evidence that elamipretide improved vision in patients with the disease, and we look forward to further evaluation in the ongoing Phase 2 study."

ReCLAIM was a Phase 1 open-label study evaluating daily subcutaneous elamipretide for 24 weeks in patients with dry AMD with non-central geographic atrophy or high-risk drusen. Patients with non-central geographic atrophy (n=15) showed a mean increase in low-luminance visual acuity, or clarity of vision in low light, of 5.4 ± 7.9 letters (baseline of 43.9 ± 19.8 letters; p=0.025) and best-corrected visual acuity, or best distance vision with glasses or contact lenses, of 4.6 ± 5.1 letters (baseline of 73.7 ± 9.5 letters; p=0.003). A significant improvement was also observed in low-luminance smallest line read correctly of -0.52 ± 0.75 (p<0.017), which corresponds to a gain of five lines on an eye chart. Patient-reported outcomes on the low-luminance and visual function questionnaires demonstrated significant improvement in daily quality-of-life measures, especially relating to low-luminance visual function. The patients with high-risk drusen (n=19; fatty deposits under the retina that can lead to future vision loss) also showed significant improvements in best corrected visual acuity, low-luminance visual acuity, reading acuity and patient-reported outcomes. Data were also presented showing similar visual acuity improvements in fellow eyes that had neovascular AMD.

Significant improvements in visual function were also observed in the open-label extension portion of ReSIGHT, a Phase 2, double-masked, placebo-controlled study investigating the safety, tolerability and efficacy of elamipretide topical ophthalmic solution for 52 weeks in 12 patients with established vision loss (greater than one year but less than 10 years) due to genetically confirmed LHON with the G11778A mutation, followed by an ongoing open-label extension in which all 12 patients participated and have completed at least 84 total weeks of treatment. Although no difference in best-corrected visual acuity was observed during the double-masked portion of the trial, trends toward improvement were observed, including significant improvement in patient-reported outcomes. The poster presentation of the week 84 open-label results showed amplification of improvement with introduction of bilateral elamipretide therapy, demonstrating significant improvements compared to baseline in best-corrected visual acuity, visual field mean deviation, contrast sensitivity and color discrimination.

"LHON is a devastating disease that causes profound and sudden vision loss in the prime of life and currently has no FDA-approved treatment," said Dr. Alfredo Sadun, UCLA Doheny Eye Institute, the primary investigator for the study. "It's encouraging that patients reported an impact on their daily activities and vision, both being key goals of a potential treatment for those with LHON."

In both studies, elamipretide was well tolerated and most adverse events were mild to moderate in severity. In the ReCLAIM study, the most commonly reported adverse events included injection site reactions. In the ReSIGHT study, adverse events occurred in a similar frequency between elamipretide and placebo-treated eyes.

"Our visual system, which has the greatest demand and highest mitochondrial density in the body, can be severely compromised by age-related or genetic mitochondrial dysfunction," said Stealth Chief Executive Officer Reenie McCarthy. "Since loss of visual function may have devastating impacts on quality of life, we are highly encouraged by this early evidence that elamipretide may have the potential to improve vision in these severe, progressive ophthalmic diseases for which there are no approved medicines. We look forward to completing enrollment in our ReCLAIM-2 study by early next year, as well as our upcoming regulatory discussion regarding LHON."

The U.S. Food and Drug Administration (FDA) has granted Fast Track designations for elamipretide for the treatment of dry AMD and LHON, as well as Orphan Drug designation for LHON. For additional information on the studies or elamipretide, please refer to Stealth's website and ClinicalTrials.gov.

About Age-Related Macular Degeneration

Age-related macular degeneration (AMD), a progressive eye condition that is the leading cause of blindness in adults, is estimated to affect approximately 10 million people in the U.S. AMD affects the center portion of the retina, called the macula, which is responsible for central vision and color perception. Although there are FDA-approved treatments for wet AMD, which affects approximately 10 percent of those suffering from the disease, there are no approved therapies for dry AMD. Dry AMD with geographic atrophy, an advanced form of dry AMD, is characterized by central blind spots leading to permanent loss of vision. The disease is a major contributor to loss of independence and diminished quality of life in older persons.

About LHON

Affecting approximately 35,000 people worldwide, LHON causes neuropathy of the optic nerve and retinal ganglion cells in the back of the eye and can lead to legal blindness. Mitochondrial dysfunction is a key factor in genetic optic neuropathies such as LHON, characterized by loss of visual function resulting from impaired cellular energetics. LHON primarily affects young men between the ages of 18 and 30. Vision problems, such as blurring or clouding of vision, may begin in one eye or both eyes at the same time. Over time, vision worsens in both eyes and often leads to severe and permanent legal blindness.

About Stealth

We are 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, collectively known as primary mitochondrial diseases, and are also involved in many common age-related diseases. We believe our lead product candidate, elamipretide, has the potential to treat both rare genetic and common age-related mitochondrial diseases. We are studying elamipretide in the following primary mitochondrial diseases: primary mitochondrial myopathy, Barth syndrome and Leber's hereditary optic neuropathy. We are also studying elamipretide in dry age-related macular degeneration. Our other pipeline candidates include SBT-272, which we are evaluating for rare neurodegenerative disease indications, and SBT-20, which we are evaluating for rare peripheral neuropathies. We have optimized our discovery platform to identify novel mitochondrial-targeted compounds, which may be nominated as therapeutic product candidates or utilized as scaffolds to deliver other compounds to mitochondria. We have assembled a highly experienced management team, board of directors and group of scientific advisors to help us achieve our mission of leading mitochondrial medicine.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Such forward-looking statements include those regarding Stealth BioTherapeutics' plans, strategies and expectations for its preclinical and clinical advancement of its drug development programs, including its ongoing clinical trials of elamipretide for the treatment of dry age-related macular degeneration and Leber's heredity optic neuropathy. Statements that are not historical facts, including statements about Stealth BioTherapeutics' beliefs, plans and expectations, are forward-looking statements. The words "anticipate," "expect," "hope," "plan," "potential," "possible," "will," "believe," "estimate," "intend," "may," "predict," "project," "would" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Stealth BioTherapeutics may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements as a result of known and unknown risks, uncertainties and other important factors, including: Stealth BioTherapeutics' ability to obtain additional funding; the ability to successfully demonstrate the efficacy and safety of Stealth BioTherapeutics' product candidates and future product candidates; the preclinical and clinical results for Stealth BioTherapeutics' product candidates, which may not support further development and marketing approval; the potential advantages of Stealth BioTherapeutics' product candidates; the content and timing of decisions made by the U.S. FDA, the EMA or other regulatory authorities, investigational review boards at clinical trial sites and publication review bodies, which may affect the initiation, timing and progress of preclinical studies and clinical trials of Stealth BioTherapeutics product candidates; Stealth BioTherapeutics' ability to obtain and maintain requisite regulatory approvals and to enroll patients in its planned clinical trials; unplanned cash requirements and expenditures; competitive factors; Stealth BioTherapeutics' ability to obtain, maintain and enforce patent and other intellectual property protection for any product candidates it is developing; and general economic and market conditions. These and other risks are described in greater detail under the caption "Risk Factors" included in Stealth BioTherapeutics' most recent Annual Report on Form 20-F filed with the Securities and Exchange Commission ("SEC"), as well as in any future filings with the SEC. Forward-looking statements represent management's current expectations and are inherently uncertain. Except as required by law, Stealth BioTherapeutics does not undertake any obligation to update forward-looking statements made by us to reflect subsequent events or circumstances.

Media Relations
dna Communications
Kate Contreras, 617-520-7088
Media@StealthBT.com 

Investor Relations
Stern Investor Relations
Lauren Stival, 212-362-1200
IR@StealthBT.com

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SOURCE Stealth BioTherapeutics

Media Relations

dna Communications
Lindsey Colegrove, 212-537-8771
media@stealthbt.com

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Stern IR
Lauren Stival, 212-362-1200
IR@stealthbt.com