Elamipretide (SS-31) in Retinal Mitochondrial Protection: A Literature Synthesis
Abstract
A survey of published preclinical and clinical research on the aromatic-cationic tetrapeptide SS-31 (elamipretide) in retinal contexts, including the ReCLAIM programme of AMD and geographic-atrophy clinical trials and preclinical models of traumatic optic neuropathy. Mechanistic emphasis is placed on cardiolipin association and inner-membrane stabilization. Reference survey only; efficacy is not asserted.
Methods
- 01Scope : SS-31 in retinal and mitochondrial research
- 02Sources : preclinical models and reported clinical study programmes
- 03Mechanism : cardiolipin binding, cristae stabilization, ROS
- 04Framing : neutral synthesis, no endpoint adjudication
Literature Synthesis
Clinical Research: The ReCLAIM Program
Three completed clinical studies make up the ReCLAIM program evaluating subcutaneous elamipretide in dry age-related macular degeneration (AMD). Two Phase 1, open-label, 24-week studies from Duke Eye Center enrolled patients with noncentral geographic atrophy [1] and with intermediate AMD and high-risk drusen [2]; both were designed primarily to assess safety and tolerability and both reported exploratory improvements in low-luminance visual acuity and reading measures, with no serious treatment-related adverse events. The subsequent Phase II ReCLAIM-2 trial (NCT03891875) randomized 176 patients and did not meet its primary visual-acuity or geographic-atrophy-area endpoints, but reported a 43-47% reduction in the progression of ellipsoid-zone attenuation — a structural marker of photoreceptor loss — versus placebo at week 48 [3]. That endpoint has since been adopted as the primary outcome for the ongoing Phase III elamipretide program. Elamipretide is one of several mitochondrial-targeted candidates surveyed in recent AMD-therapeutics reviews [4,5].
Mechanism: Cardiolipin Binding and Cristae Stabilization
Elamipretide's proposed mechanism centers on selective, non-receptor-mediated binding to cardiolipin, an anionic phospholipid concentrated in the inner mitochondrial membrane [6,7]. By associating with cardiolipin, the aromatic-cationic tetrapeptide is reported to stabilize cristae architecture, support electron-transport-chain organization, and reduce reactive-oxygen-species leakage [6,7]. This mechanism has also been studied outside the retina, including in Barth syndrome cardiomyopathy — a genetic disorder of cardiolipin remodeling — where mitochondrial-targeted peptides are reviewed as an investigational strategy [8].
Preclinical Neuroprotection: Optic Nerve and Retinal Ganglion Cells
Independent of the AMD clinical program, elamipretide (studied under the earlier designation MTP-131) has been evaluated as a neuroprotective agent for retinal ganglion cells (RGCs) in rodent models of acute optic nerve injury. In a sonication-induced traumatic optic neuropathy model, intravitreal elamipretide combined with the TNF inhibitor etanercept produced a 21% increase in RGC survival over controls, with subcutaneous elamipretide alone showing a 17% increase [9]; a related polytherapy study in the same injury model has since been published [10]. In a methanol-poisoning model of combined optic nerve, retinal, and brain toxicity, elamipretide co-administered with methylprednisolone improved histological retinal-degeneration scores and reduced retinal apoptosis relative to injury controls [11]. Elamipretide-class tetrapeptides have also been evaluated for neuroprotection in non-ocular CNS injury models, including spinal cord injury [12], consistent with a mechanism that generalizes across central-nervous-system tissue rather than being retina-specific.
Documented References
- [1]
Mettu PS, Allingham MJ, Cousins SW. (2022) Phase 1 Clinical Trial of Elamipretide in Dry Age-Related Macular Degeneration and Noncentral Geographic Atrophy: ReCLAIM NCGA Study.
Ophthalmology Science
View on PubMed - [2]
Allingham MJ, Mettu PS, Cousins SW. (2022) Phase 1 Clinical Trial of Elamipretide in Intermediate Age-Related Macular Degeneration and High-Risk Drusen: ReCLAIM High-Risk Drusen Study.
Ophthalmology Science
View on PubMed - [3]
Ehlers JP, et al. (2025) ReCLAIM-2: A Randomized Phase II Clinical Trial Evaluating Elamipretide in Age-related Macular Degeneration, Geographic Atrophy Growth, Visual Function, and Ellipsoid Zone Preservation.
Ophthalmology Science
View on PubMed - [4]
Nashine S. (2021) Potential Therapeutic Candidates for Age-Related Macular Degeneration (AMD).
Cells
View on PubMed - [5]
Samanta A, et al. (2021) Emerging Therapies in Nonexudative Age-Related Macular Degeneration in 2020.
Asia-Pacific Journal of Ophthalmology
View on PubMed - [6]
Szeto HH. (2014) First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics.
British Journal of Pharmacology
View on PubMed - [7]
Tung C, et al. (2025) Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential.
International Journal of Molecular Sciences
View on PubMed - [8]
Sabbah HN. (2021) Barth syndrome cardiomyopathy: targeting the mitochondria with elamipretide.
Heart Failure Reviews
View on PubMed - [9]
Tse BC, et al. (2020) Mitochondrial targeted therapy with elamipretide (MTP-131) as an adjunct to tumor necrosis factor inhibition for traumatic optic neuropathy in the acute setting.
Experimental Eye Research
View on PubMed - [10]
Tse DT, et al. (2025) A Polytherapy Intervention in an Experimental Traumatic Optic Neuropathy Mouse Model.
Ophthalmic Plastic and Reconstructive Surgery
View on PubMed - [11]
Bulbul O, et al. (2025) Effect of elamipretide and methylprednisolone treatment on optic nerve, retina and brain damage in a methanol poisoning model.
Cutaneous and Ocular Toxicology
View on PubMed - [12]
Ravenscraft B, et al. (2025) Mitochondrial Cardiolipin-Targeted Tetrapeptide, SS-31, Exerts Neuroprotective Effects Within In Vitro and In Vivo Models of Spinal Cord Injury.
International Journal of Molecular Sciences
View on PubMed
References point to published, third-party scientific literature, provided for research context. Citation of a study is not an endorsement of any use of this material.
DISCLOSURE : This report presents anonymized in-silico and/or observational reference data. It does not establish a causal relationship between any catalogued material and any physiological outcome, and it is not a claim of safety, efficacy, or benefit.
Compounds referenced
This note surveys published work on the following compound. They are research materials, not treatments, and nothing here indicates they are suitable for any use in humans.