Why cardiolipin is part of the story
SS-31, also known as elamipretide, is a peptide investigated for its interaction with cardiolipin, a lipid in the inner mitochondrial membrane. That membrane is where components of the electron-transport machinery operate. Researchers therefore ask whether changing lipid–protein interactions can help preserve energy production in a defined experimental setting. [1]
Birk and colleagues examined this question using membrane models and mitochondrial preparations. Their measurements linked the interaction with cardiolipin to cytochrome c function and ATP synthesis. This provides a mechanistic rationale for clinical investigation, while leaving the clinical question open. [1]
What the selected sources show
A focused reading list. The model, result and interpretation belong together.
Birk et al.
SS-31 interacted with cardiolipin-containing membranes and supported electron transfer and ATP synthesis in the tested systems.
Interpretation: An effect in isolated mitochondria does not establish better exercise capacity or everyday energy in people.
Karaa et al.
At 24 weeks, elamipretide did not significantly improve either primary endpoint—six-minute walking distance or total fatigue—compared with placebo.
Interpretation: The population had genetically confirmed primary mitochondrial myopathy. Exploratory subgroup signals do not replace the overall primary result.
U.S. Food and Drug Administration
Forzinity (elamipretide) received accelerated approval in September 2025 for Barth syndrome in patients weighing at least 30 kg, based on a knee muscle-strength endpoint.
Interpretation: The approval requires confirmation of patient benefit. It concerns a specific medicine and disease context, not every SS-31 preparation.
Clinical results depend on the disease and endpoint
MMPOWER-3 tested function in people, rather than mitochondrial activity in a laboratory preparation. Its negative primary results are central to interpreting SS-31: a plausible mechanism did not produce a demonstrated advantage on walking distance or fatigue in the overall trial population. [2]
Barth syndrome represents a different clinical setting. The FDA's 2025 accelerated approval of Forzinity was based on an improvement in knee extensor muscle strength considered reasonably likely to predict patient benefit. The agency required a confirmatory randomized trial. This distinction preserves both the actual clinical development and the uncertainty that remains. [3]
Keep membrane function and physical function distinct
“Mitochondrial function” can refer to several endpoints. Oxygen consumption in an isolated preparation, ATP production, walking distance and a fatigue score describe different levels of biology. A useful article names the measurement instead of treating them as equivalent forms of increased energy.
When following this field, look for a defined diagnosis, an appropriate comparison and an endpoint selected before analysis. A subgroup observation can suggest a new question, but it needs its own prospective test. Research into SS-31 is therefore best framed around membrane biology and disease-specific functional outcomes, with each conclusion tied to the study that produced it.
References
- Birk et al. (2014). Targeting mitochondrial cardiolipin and the cytochrome c/cardiolipin complex to promote electron transport and optimize mitochondrial ATP synthesisDOI: 10.1111/bph.12468
- Karaa et al. (2023). Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical TrialDOI: 10.1212/WNL.0000000000207402
- U.S. Food and Drug Administration (2025). FDA Grants Accelerated Approval to First Treatment for Barth Syndrome
Two primary research publications and one primary regulatory announcement were checked. The Birk indexed abstract and MMPOWER-3 indexed/full-text record informed the study summaries. The FDA announcement supplies clinical context, not an additional efficacy trial.