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.
Relevant Reference Materials
This report's structural and literature findings are studied against the following catalogued reference material.