Stealth BioTherapeutics Initiates Two Phase 2 Trials Evaluating Elamipretide for the Treatment of Heart Failure

Trials to evaluate potential treatment option for heart failure patients with either reduced or preserved ejection fraction

BOSTON – June 27, 2016 – Stealth BioTherapeutics (Stealth), a clinical-stage biopharmaceutical company developing investigational drugs to treat mitochondrial dysfunction, today announced the initiation of two Phase 2 studies evaluating elamipretide in heart failure: PROGRESS-HF in patients with heart failure with reduced ejection fraction and RESTORE-HF in those with preserved ejection fraction. Top-line data from each are expected in the second half of 2017.

“The heart’s reduced ability to relax and contract during heart failure may be linked to mitochondrial dysfunction and a resulting lack of energy in heart muscle,” said Stealth Vice President of Clinical Development Jim Carr. “Since muscle is required for both pumping and re-filling the heart, we believe elamipretide could address this lack of energy in the heart muscle in the two major forms of heart failure by improving mitochondrial function.”

PROGRESS-HF and RESTORE-HF are randomized, double-blind, placebo-controlled trials to evaluate the effects of four weeks’ treatment with daily subcutaneous injections of elamipretide on left ventricular function in patients with stable heart failure with reduced ejection fraction (PROGRESS-HF) or preserved ejection fraction (RESTORE-HF).

The primary endpoint of PROGRESS-HF is change from baseline in the volume of blood remaining in the left ventricle at end of contraction, as assessed by cardiac magnetic resonance imaging (MRI). Secondary endpoints will include additional measures of cardiac function, including ejection fraction, by echocardiography and MRI. The primary endpoints of RESTORE-HF are changes in diastolic heart function at rest and during submaximal stress, as assessed by echocardiography. Secondary endpoints include changes in exercise capacity, as measured by the six-minute walk test, and responses to the SF36 patient-reported health survey.

“Our initiation of these Phase 2 trials marks an important milestone for Stealth and the progression of our cardiorenal program for elamipretide. Following the promising findings from our Phase 1 PREVIEW trial in heart failure, we hope to demonstrate improvements in heart function across both types of heart failure with longer-term dosing,” said Stealth Chief Executive Officer Reenie McCarthy.

For additional information on PROGRESS-HF, RESTORE-HF or elamipretide, please refer to Stealth’s website and

About Heart Failure

Heart failure affects approximately 21 million people in the United States and Europe, and the incidence is anticipated to increase as the population continues to age. The disease is characterized by a reduced ability to relax and contract the heart to pump blood throughout the body. Heart failure comes in two forms, based on changes in the amount of blood the left ventricle pumps out with each contraction, known as ejection fraction. Both forms, heart failure with reduced ejection fraction and heart failure with preserved ejection fraction, are associated with mitochondrial dysfunction and the resulting lack of energy in the heart muscle. There are currently no FDA-approved treatments for heart failure with preserved ejection fraction, and only limited treatments for heart failure with reduced ejection fraction.

About Elamipretide

Stealth’s lead candidate, elamipretide, is an investigational drug with the potential to modify disease by preserving energetics and restoring normal energy production in mitochondria, while decreasing oxidative stress. The energetics from mitochondria maintain healthy physiology and prevent disease. This mitochondria-targeted candidate is being developed for both rare and common diseases.

Stealth BioTherapeutics: Leading Mitochondrial Medicine

Stealth BioTherapeutics is a privately held biopharmaceutical company committed to bringing mitochondrial therapies to patients to treat both rare and common diseases. Stealth’s clinical development program is focused along several core therapeutic areas, including primary mitochondrial diseases, cardiorenal diseases and ophthalmic disorders. More information regarding Stealth and its pipeline is available at

# # #


Media Relations
dna Communications

Taylor Ramsey
Phone: 617-520-7018

Investor Relations
Stern IR

Beth DelGiacco
Phone: 212-362-1200