Stealth BioTherapeutics Granted Orphan Drug Designation of Elamipretide for Treatment of Leber’s Hereditary Optic Neuropathy

BOSTON – April 30, 2018 – Stealth BioTherapeutics (Stealth), a clinical-stage biopharmaceutical company developing therapeutics to treat mitochondrial dysfunction, announced that the U.S. Food and Drug Administration (FDA) Office of Orphan Products Development has granted Orphan Drug Designation to Stealth’s investigational drug candidate, elamipretide, for the treatment of Leber’s hereditary optic neuropathy (LHON).

LHON is an inherited mitochondrial disease that causes loss of central vision due to damage to neurons in the retina, called retinal ganglion cells. The disease, which affects approximately 10,000 people in the United States, can lead to legal blindness, and there are no FDA-approved therapies to address it.

Orphan Drug Designation provides various benefits for an investigational drug, including seven-year exclusivity after marketing approval is received. Elamipretide has also been granted Orphan Drug Designation for the treatment of primary mitochondrial myopathy and Barth syndrome, two other rare primary mitochondrial diseases.

“This designation further underscores our commitment to develop potential therapies for patients suffering from rare mitochondrial diseases,” said Reenie McCarthy, Stealth’s chief executive officer. “This third Orphan Drug Designation for elamipretide highlights our significant progress within our present rare disease focus, as we continue to advance our longer-term strategy of developing therapies for age-related diseases.”

In December 2017, Stealth was also granted Fast Track designation for elamipretide for the treatment of LHON. Stealth is currently evaluating the safety, tolerability and efficacy of topical eye drop delivery of elamipretide in patients with LHON in ReSIGHT, a phase 2, prospective, double-masked, vehicle-controlled clinical study initiated in 2016. Top-line results from the study are expected later this year.

For additional information on the ReSIGHT study or elamipretide, please refer to Stealth’s website.

About Leber’s Hereditary Optic Neuropathy

Affecting approximately 10,000 people in the United States, 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 privately held clinical-stage biotechnology company focused on the development of therapeutics for diseases involving mitochondrial dysfunction. We believe there is a strong rationale for our lead product candidate, elamipretide, in indications in these diseases based on encouraging preclinical and early clinical data. We are investigating elamipretide in three primary mitochondrial diseases – primary mitochondrial myopathy (PMM), Barth syndrome and LHON – as well as in dry age-related macular degeneration. We received Orphan Drug Designation of elamipretide from the FDA for the treatment of PMM in September 2017 and for Barth syndrome in March 2018. We have a promising pipeline of compounds we expect to develop in additional rare mitochondrial diseases, as well as in diseases associated with aging in which mitochondrial dysfunction has been shown to be involved. To learn more information about us and our pipeline, visit

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