Claimed effect · SS-31 (elamipretide)

Does SS-31 (elamipretide) help with primary mitochondrial myopathy?

D
Grade D — no human evidence1 phase 3 RCT (n=218) · effect size: not measurable
Short answerNo human evidence. As of 3 September 2026, only 1 phase 3 RCT (n=218) exists for SS-31 (elamipretide) for primary mitochondrial myopathy. MMPOWER-3, the pivotal trial in the larger primary-mitochondrial-myopathy population, was negative on both primary endpoints at 24 weeks.

What the studies show

MMPOWER-3, the pivotal trial in the larger primary-mitochondrial-myopathy population, was negative on both primary endpoints at 24 weeks.

“The study did not meet its primary endpoints assessing changes in the 6MWT and PMMSA total fatigue score (TFS).”

Verbatim, from the abstractKaraa A, et al. Efficacy and safety of elamipretide in individuals with primary mitochondrial myopathy: the MMPOWER-3 randomized clinical trial. Neurology, 2023;101:e238–e252

Animal studies, cell studies, or anecdotes only. This is where almost every viral peptide sits. Promising and proven are different words for a reason.

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In context

SS-31, developed as elamipretide, is a four-amino-acid peptide that concentrates in mitochondria and binds cardiolipin, a lipid of the inner membrane. After a decade of trials it was approved in the United States in September 2025 for Barth syndrome, an ultra-rare genetic disease — on the strength of an open-label extension, since its randomised crossover missed both primary endpoints. Larger randomised trials in primary mitochondrial myopathy and in heart failure were negative. It is a genuine, narrowly approved medicine, not a general 'mitochondrial' or anti-ageing treatment.

SS-31 (elamipretide) is approved (rx, us; barth syndrome only). Legal status differs by country — see the regulation section or the jurisdiction pages.

Questions

Is SS-31 (elamipretide) proven to help with primary mitochondrial myopathy?
No. There is no human evidence for it (1 phase 3 RCT (n=218)); the claim rests on animal or cell studies and LYO grades it D.
What studies are behind the grade?
MMPOWER-3, the pivotal trial in the larger primary-mitochondrial-myopathy population, was negative on both primary endpoints at 24 weeks.
Is SS-31 (elamipretide) approved for this?
SS-31 (elamipretide) is an approved medicine (Approved (Rx, US; Barth syndrome only)); whether this particular outcome is a licensed indication is stated on the compound page's regulation section.

Other outcomes for SS-31 (elamipretide)

Written and maintained by LYO Research — how pages are written and checked. Reviewed 3 September 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →