Mechanizm działania
SS-31 accumulates at the inner mitochondrial membrane independently of membrane potential and selectively binds cardiolipin there via electrostatic and hydrophobic interactions, a phospholipid found almost exclusively in this membrane that is important for cristae architecture and the organization of the respiratory chain. A review by Szeto (2014) describes cardiolipin binding as inhibiting the conversion of cytochrome c into a peroxidase while preserving its electron-carrier function, thereby stabilizing oxidative phosphorylation and reducing the formation of reactive oxygen species in cell and animal models. On this basis, the substance was first studied in preclinical models of ischemia-reperfusion injury, heart failure and mitochondrial disease; it was subsequently tested in randomized human trials, including in heart failure, after myocardial infarction and in mitochondrial myopathy, several of which missed their primary endpoints. To what extent the mechanistic findings translate to humans therefore remains open. On pharmacokinetics: the US prescribing information for FORZINITY states no numeric elimination half-life; Szeto (2014) reports a human elimination half-life of approximately 4 hours, based on phase 1 data.
Stan dowodów naukowych
The evidence on elamipretide is unusually split. The preclinical work was followed by a broad clinical program: MMPOWER, a randomized dose-escalation trial in primary mitochondrial myopathy (Karaa et al., 2018); the phase 3 trial MMPOWER-3 with 218 participants, which missed both of its primary endpoints (6-minute walk test and fatigue score) (Karaa et al., 2023); and the phase 2 trial ReCLAIM-2 in dry age-related macular degeneration, which likewise did not meet its primary endpoints (Ehlers et al., 2025). The cardiac phase 2 trials were negative as well: in PROGRESS-HF in heart failure with reduced ejection fraction, elamipretide was well tolerated but did not improve left ventricular end-systolic volume at 4 weeks (Butler et al., 2020), and in EMBRACE STEMI after myocardial infarction, treatment was not associated with a reduction in infarct size (Gibson et al., 2016). MMPOWER-3 and its open-label extension were terminated after the primary endpoints were missed (ClinicalTrials.gov NCT03323749, NCT02976038). In Barth syndrome, the randomized crossover part of the TAZPOWER trial in 12 participants missed its primary endpoints, while the open-label extension showed improvements including knee extensor strength (Reid Thompson et al., 2021). On this basis, the FDA granted accelerated approval of FORZINITY for Barth syndrome on September 19, 2025 (NDA 215244), based on knee extensor strength as an intermediate clinical endpoint; under this approval pathway, confirmation of clinical benefit in further studies is still pending. The approval is a regulatory statement for a very rare indication and does not establish efficacy in the other studied indications. All of these data were generated with the pharmaceutical product under controlled trial conditions; they permit no conclusions about the efficacy or safety of research-grade material.
Przechowywanie i postępowanie
Lyophilized peptides are generally stored cool, dry and protected from light; for long-term storage, the literature describes temperatures of 2 to 8 °C or below. After reconstitution, peptide solutions are typically kept refrigerated and used within a few days; repeated freeze-thaw cycles are considered unfavorable. No product-specific stability data exist for research-grade material.
Pytania dotyczące stanu badań
- What is SS-31 (elamipretide) studied for in research?
- SS-31 is used primarily as a tool for studying cardiolipin biology and mitochondrial bioenergetics, for example in preclinical models of ischemia-reperfusion injury, heart failure and age-related mitochondrial dysfunction. Clinically, the substance has been tested in primary mitochondrial myopathy (the MMPOWER program), in Barth syndrome (TAZPOWER), in dry age-related macular degeneration (ReCLAIM-2) and in heart failure (PROGRESS-HF) and after myocardial infarction (EMBRACE STEMI). The 2025 accelerated FDA approval is narrow: it covers only the improvement of muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg, a very rare genetic disorder of cardiolipin metabolism.
- What is the state of the evidence on SS-31 (elamipretide)?
- The pharmaceutical product FORZINITY has been approved in the United States under the accelerated pathway since September 2025 to improve muscle strength in Barth syndrome in patients weighing at least 30 kg, based on knee extensor strength as an intermediate clinical endpoint from the small TAZPOWER trial. At the same time, the two largest trials, MMPOWER-3 in mitochondrial myopathy and ReCLAIM-2 in dry macular degeneration, missed their primary endpoints, as did the cardiac phase 2 trials PROGRESS-HF and EMBRACE STEMI; MMPOWER-3 and its open-label extension were subsequently terminated. The approval therefore does not establish broad efficacy; the data refer to the medicinal product under trial conditions and cannot be transferred to research-grade material.
Źródła
- Szeto, Br J Pharmacol 2014DOI: 10.1111/bph.12461PMID: 24117165
- Gibson et al., Eur Heart J 2016 (EMBRACE STEMI, NCT01572909)DOI: 10.1093/eurheartj/ehv597PMID: 26586786
- Karaa et al., Neurology 2018 (MMPOWER)DOI: 10.1212/WNL.0000000000005255PMID: 29500292
- Butler et al., J Card Fail 2020 (PROGRESS-HF, NCT02788747)DOI: 10.1016/j.cardfail.2020.02.001PMID: 32068002
- Reid Thompson et al., Genetics in Medicine 2021 (TAZPOWER)DOI: 10.1038/s41436-020-01006-8PMID: 33077895
- Karaa et al., Neurology 2023 (MMPOWER-3)DOI: 10.1212/WNL.0000000000207402PMID: 37268435
- ClinicalTrials.gov NCT03323749 (MMPOWER-3, terminated)
- ClinicalTrials.gov NCT02976038 (MMPOWER-3 open-label extension, terminated)
- Ehlers et al., Ophthalmol Sci 2025 (ReCLAIM-2)DOI: 10.1016/j.xops.2024.100628PMID: 39605874
- FDA: FORZINITY Approval Letter, NDA 215244 (2025)
- Shirley, Drugs 2026 (Elamipretide: First Approval)DOI: 10.1007/s40265-025-02269-8PMID: 41335372