Omaveloxolone for the Treatment of Friedreich Ataxia: Efficacy, Safety, and Future Perspectives

Naghipour S, Corben LA, Hulme AJ, Dottori M, Delatycki MB, Lees JG, Lim SY. Omaveloxolone for the Treatment of Friedreich Ataxia: Efficacy, Safety, and Future Perspectives. Mov Disord. 2024 Nov 19. doi: 10.1002/mds.30070. Epub ahead of print. PMID: 39559924. 

The scarcity literature addressing the cardiovascular effects omaveloxolone in FRDA is concerning, especially considering that cardiomyopathy is the primary cause of mortality in affected individuals. Furthermore, the reported potential of omaveloxolone to induce mil elevations in B-natriuretic peptide (BNP), a known marker of heart failure, adds to this concern. Thus, those individuals with FRDA who have cardiomyopathy are advised to monitor BNP levels while using omaveloxolone. In this viewpoint, we examine the current literature on the efficacy and safety of omaveloxolone in treating FRDA, with a focus on its potential impact on cardiovascular health.

Assessment of the Clinical Interactions of GAA Repeat Expansions in FGF14 and FXN

Gerhart BJ, Pellerin D, Danzi MC, Zuchner S, Brais B, Matos-Rodrigues G, Nussenzweig A, Usdin K, Park CC, Napierala JS, Lynch DR, Napierala M. Assessment of the Clinical Interactions of GAA Repeat Expansions in FGF14 and FXN. Neurol Genet. 2024 Nov 20;10(6):e200210. doi: 10.1212/NXG.0000000000200210. PMID: 39574782; PMCID: PMC11581763.

Despite both molecular and clinical similarities between FRDA and SCA27B, the length of the GAA repeats in the FGF14 gene, including potentially pathogenic alleles, did not influence the clinical presentation of FRDA.

Recurrent DNA nicks drive massive expansions of (GAA)n repeats

Li L, Scott WS, Khristich AN, Armenia JF, Mirkin SM. Recurrent DNA nicks drive massive expansions of (GAA)n repeats. Proc Natl Acad Sci U S A. 2024 Dec 3;121(49):e2413298121. doi: 10.1073/pnas.2413298121. Epub 2024 Nov 25. PMID: 39585990.

 We found that DNA nicks 5' of the (GAA)100 run led to a dramatic increase in both the rate and scale of its expansion in dividing cells. Strikingly, they also promoted large-scale expansions of carrier- and large normal-size (GAA)n repeats, recreating, in a model system, the expansion events that occur in human pedigrees. DNA nicks 3' of the (GAA)100 repeat led to a smaller but significant increase in the expansion rate as well. Our genetic analysis implies that in dividing cells, conversion of nicks into double-strand breaks (DSBs) during DNA replication followed by DSB or fork repair leads to repeat expansions. Finally, we showed that 5' GAA-strand nicks increase expansion frequency in nondividing yeast cells, albeit to a lesser extent than in dividing cells.

Two-stage binding of mitochondrial ferredoxin-2 to the core iron-sulfur cluster assembly complex

Steinhilper R, Boß L, Freibert SA, Schulz V, Krapoth N, Kaltwasser S, Lill R, Murphy BJ. Two-stage binding of mitochondrial ferredoxin-2 to the core iron-sulfur cluster assembly complex. Nat Commun. 2024 Dec 4;15(1):10559. doi: 10.1038/s41467-024-54585-4. PMID: 39632806; PMCID: PMC11618653.  

The structural interaction of FDX2 with the complex remains unclear. Here, we present cryo-EM structures of the human FDX2-bound core ISC complex showing that FDX2 and FXN compete for overlapping binding sites. FDX2 binds in either a 'distal' conformation, where its helix F interacts electrostatically with an arginine patch of NFS1, or a 'proximal' conformation, where this interaction tightens and the FDX2-specific C terminus binds to NFS1, facilitating the movement of the [2Fe-2S] cluster of FDX2 closer to the ISCU2 FeS cluster assembly site for rapid electron transfer. Structure-based mutational studies verify the contact areas of FDX2 within the core ISC complex.

Stabilization of expandable DNA repeats by the replication factor Mcm10 promotes cell viability

Masnovo, C., Paleiov, Z., Dovrat, D. et al. Stabilization of expandable DNA repeats by the replication factor Mcm10 promotes cell viability. Nat Commun 15, 10532 (2024). doi:10.1038/s41467-024-54977-6  

Here, we show that deficiency of the essential replisome component Mcm10 dramatically elevates (GAA)n repeat instability in a budding yeast model by loss of proper CMG helicase interaction. When repair is inefficient, such as in the case of RPA depletion, breakage of under-replicated repetitive DNA can occur during G2/M, leading to loss of essential genes and cell death. We hypothesize that the CMG-Mcm10 interaction promotes replication through hard-to-replicate regions, assuring genome stability and cell survival.

Therapeutic hypoxia for mitochondrial disease via enhancement of hemoglobin affinity and inhibition of HIF-2α

Therapeutic hypoxia for mitochondrial disease via enhancement of hemoglobin affinity and inhibition of HIF-2α. Hong Wang, … , Fumito Ichinose, Vamsi K. Mootha. Published December 2, 2024. J Clin Invest. 2024;134(23):e185569. doi:10.1172/JCI185569. 

Our results provide preclinical proof of concept that simultaneously enhancing Hb oxygen affinity while antagonizing HIF-2α can mimic the effects of continuous hypoxic breathing for therapeutic benefit. The regimen did not confer as impressive a lifespan rescue as continuous breathing of 11% oxygen, probably because GBT440 has a short half-life (6), and for practical reasons, we treated the mice five weekdays per week. Future studies in humans are required to evaluate the safety of this combination, given that hypoxia can be associated with acute and long-term side effects. Such safety studies could pave the path for first-in-human “hypoxia-in-a-pill” trials in patients with mitochondrial disease.

Safeguarding the brain from oxidative damage

Kyung Hee Lee, Un Jeng Kim, Bae Hwan Lee, Myeounghoon Cha, Safeguarding the brain from oxidative damage, Free Radical Biology and Medicine, Volume 226, 2025, Pages 143-157, ISSN 0891-5849, doi:10.1016/j.freeradbiomed.2024.11.019. 

This paper aims to provide a concise and objective review of the oxidative and antioxidant pathways and their potential therapeutic applications in treating oxidative injury in the brain.

Exploring neuropsychiatric symptoms in Friedreich ataxia

Karamazovova, S., Stovickova, L., Jester, D.J. et al. Exploring neuropsychiatric symptoms in Friedreich ataxia. Sci Rep 14, 29076 (2024). doi:10.1038/s41598-024-80258-9 

 In conclusion, our findings show that NPS are common in FRDA and manifest not only as depression and anxiety but also as decreased motivation. It is difficult to distinguish whether these NPS are due to the neurodegenerative process or to the burden of living with a progressive, devastating disease, but in any case they need to be considered in clinical care.

Ferroptosis—disease perils and therapeutic promise

Ashley R. Brown et al. ,Ferroptosis—disease perils and therapeutic promise.Science386,848-849(2024).DOI:10.1126/science.adn703 

Identifying new strategies to inhibit ferroptosis offers therapeutic promise in contexts where ferroptotic cell death contributes to disease progression. By contrast, selective induction of ferroptosis is a promising approach in cancer therapeutics. Continuing discoveries about the mechanisms governing ferroptosis are likely to improve our understanding of disease biology and provide ideas that may assist in the diagnosis and treatment of diverse human maladies.

Therapeutic Activity of a Haematopoietic Stem Cell-Delivered Tissue-Penetrating Peptide in Friedreich's Ataxia Models

Pido, Jeffrey and Shaban, Enas and Moula, Shefta and Chritchely, Bethan and Whittaker, Thomas and Svensson, Stina and Anjomani Virmouni, Sara and Kalef-Ezra, Ester and Carr, Lucinda and Hassell, Jane and Thrasher, Adrian J. and Kurian, Manju A. and Santilli, Giorgia and Sala, Arturo and Administrator, Sneak Peek, Therapeutic Activity of a Haematopoietic Stem Cell-Delivered Tissue-Penetrating Peptide in Friedreich's Ataxia Models. doi:10.2139/ssrn.5026639 

We developed a replacement strategy for this disease by designing a fusion peptide containing secretion and tissue penetrating sequences at the amino terminus of the frataxin precursor protein. Secretion and penetration of the fusion peptide was validated in experiments that confirmed its ability to localise in the mitochondria and rescue the biochemical defects and apoptotic phenotype of FRDA patient cells, in vitro. Autologous transplantation of the modified HSPCs resulted in stable secretion of the peptide in the blood stream of recipient animals, impacting disease progression by delaying the manifestation of motor-coordination/sensory symptoms, paralleled by improved biochemical and anatomical parameters.