Research explained · Reviewed September 15, 2026
SS-31, also called elamipretide, is a compelling example of mitochondrial research reaching clinical development. Its story includes a disease-specific approval and trials that help sharpen the next research questions.
Why target mitochondrial membranes?
Elamipretide is a tetrapeptide studied for its interaction with cardiolipin, a lipid important to mitochondrial membrane biology. This gives researchers a focused way to investigate mitochondrial function. A clinical study in Barth syndrome explored this approach in a genetic disorder affecting cardiolipin metabolism. Read the Barth syndrome trial.
A concrete clinical milestone
On September 19, 2025, the U.S. FDA granted accelerated approval to Forzinity, an elamipretide product, to improve muscle strength in people with Barth syndrome weighing at least 30 kg. The supporting study enrolled 12 participants. The approval was based on knee-extensor strength increases observed during longer open-label follow-up; the initial randomized portion did not demonstrate superiority on its primary walking and fatigue endpoints. Read the approval and trial summary.
Accelerated approval recognizes a promising result while further studies are required to confirm clinical benefit. That is both real progress and a continuing scientific process. This U.S. decision applies to a specific medicine and indication; it does not establish Canadian authorization or equivalence for other products labelled SS-31.
What the broader trials teach us
In MMPOWER-3, 218 adults with primary mitochondrial myopathy were randomized to elamipretide or placebo. At 24 weeks, the study did not meet its primary walking-distance and fatigue endpoints. That result matters because different mitochondrial disorders need not respond in the same way. Read the phase 3 study.
A subsequent analysis explored whether genetic subgroups differed in response and described a more targeted follow-up trial. These subgroup findings are a direction to test prospectively, rather than a replacement for the original trial result. Read the genotype-focused analysis.
Where the optimism is strongest
The most exciting part is the move toward precise questions: which mitochondrial disorder, which biological feature and which patient outcome? A walking test, a muscle-strength measure and a laboratory energy measurement each tell a different part of the story.
Elamipretide’s development shows how a mechanistic idea can become a clinical programme and reach a specific regulatory milestone. The next advances depend on confirming benefits in well-defined groups. Those are worthwhile possibilities to follow, while keeping general longevity or wellness claims separate from the outcomes actually studied.