New Treatments for Friedreich’s

AtaxiaLisa Bartoli

Sasha FarinaGabriel Epshtein

Alexandra Cerulli-Kanellopulos

November 3rd, 2015

PHM142 Fall 2015Coordinator: Dr. Jeffrey HendersonInstructor: Dr. David Hampson

Table of Contents• Introduction

• Treatments

• Mitochondrial function-related drugs

• Deferiprone

• Idebenone

• Drugs to increase FXN

• Erythropoietin

• Nicotinimide

• Interferon gamma

• Gene therapy

• Summary

Introduction• What is the disease?

• Who gets it?

• What are the signs and symptoms?

• Low frataxin → Iron accumulation in the mitochondria → oxidative stress → fenton reaction

Frataxin Function

Mitochondrial function-related drugs:Deferiprone

• Deferiprone: good candidate drug

• Can cross the BBB and has low iron affinity

• Lipid soluble iron chelator

• Facilitates the export of iron to extracellular transferrin and pre-erythroid cells

• Shown to reduce the overall iron content in the dendate nucleus + slight improvement in ataxia related symptoms

• Dosing is important! High levels correlated to worsening symptoms; low doses showed some benefits for patients with mild symptoms of the disorder

Mitochondrial function-related drugs:Idebenone

• Strong antioxidant properties

• Shown to significantly reduce cardiac hypertrophy associated with the cardiomyopathy of Friedreich’s ataxia; no effect shown in patients with little cardiac hypertrophy

• Long-term use correlates to slight improvement of neurological symptoms

Erythropoietin (EPO)• EPO is a hormone produced by the kidneys that

promotes red blood cell synthesis (erythropoeisis) in the bone marrow

• Recent studies suggest EPO may be promising new treatment for friedreich’s ataxia

• Human recombinant erythropoeitin (rhuEPO) lead to an increase in frataxin protein levels in vitro

• Human Fibroblast, cardiomycyte and primary lymphocyte cells from FRDA patients and mouse neural cells were all given rhuEPO (Sturm et al)

• Frataxin protein levels increased significantly and in a dose-dependent manner

Erythropoietin (EPO)

• In vivo studies were conflicting however:

• one study claimed that EPO had no significant effect on frataxin levels, but had a small sample size of 16 patients (Mariotti et al)

• other studies showed an increase in frataxin protein, but mRNA expression was unchanged

• suggests EPO regulates frataxin post translationally

Erythropoietin (EPO) Mechanism• Current mechanism of action of EPO on frataxin is unknown

• Studies suggest it acts on frataxin post-translationally (Acquaviva et al)

• No increase in frataxin mRNA

• Possibly increasing protein half-life

• Also EPO increases frataxin levels independently of EPO receptor (Sturm et al)

• rhuEPO (which can bind receptor) increased frataxin protein but not frataxin mRNA

• carbamylated EPO (which cannot bind receptor) also increased frataxin protein to the same degree as rhuEPO, again frataxin mRNA did not increase

Histone Deacetylase Inhibitors: Nicotinamide

• Newer techniques focusing more on countering the silencing of the gene

• Expanded GAA repeats induce heterochromatin formation (condensed DNA) and silence expression

• Locus goes from acetylation (active) to methylation (methylation) (Gottesfeld et al.)

• Inhibiting histone deacetylases (HDACs) → could counter silencing of frataxin gene

• Nicotinamide (vitamin B3): HDAC inhibitor (Lynch et al.)

• Good bioavailability, tissue penetration

• Especially blood brain barrier

Histone Deacetylase Inhibitors: Nicotinamide

• Landmark Study: Patients given single doses and repeated doses of 2-8g of nicotinamide (single dose, 5 days, 8 weeks) (Libri et al.)

• Increased frataxin protein concentration in peripheral mononuclear blood cells

• Upregulation of frataxin mRNA

• Associated with alterations in chromatin structure

• ie reduction in heterochromatin modifications at frataxin gene locus

• However, no significant clinical improvements to neurological measures

Histone Deacetylase Inhibitors: RG2833

• Another study assessed neuronal cell lines (Soragni et al.)

• Created ataxia neurons from Induced pluripotent stem cells (derived from patients)

• 4 cohorts of patients: ranging from 30mg/day to

240mg/day

• Increased frataxin mRNA and protein concentrations

• Epigenetic changes→ Reactivation of gene through

acetylation

Gene Therapy• GAA triplet repeat in the intron region of the FXN gene

reduces frataxin expression

• Viral vectors can be used to introduce FXN in FDRA cells by integrating into host genome

• In mouse studies HSV-1 viral vectors inserted into FDRA fibroblasts resulted in decreased oxidative stress and increased frataxin levels (Gomez-Sebastian et al)

• In FXN knockout mice the neurological defects were reversed after gene therapy with HSV-1 vector containing normal human FXN gene (Lim et al)

• Other kinds of viral vectors such as adenoviruses and retroviruses had a similar effect, reducing oxidative damage and increasing lifespan

• Bacterial and Yeast chromosomes containing the LXN gene have also shown to be effective vectors in FXN knockout mice

Summary• Friedreichs ataxia is an autosomal recessive inherited disease that leads to degeneration of the nervous system

• Mutation has increased copies of the trinucleotide repeat GAA

• EPO shows promise as a potential new treatment to increase frataxin protein levels (mechanism unknown but regulates frataxin post translationally and independently of EPO receptor)

• Deferiprone and idebenone are two mitochondrial function-related drugs

• Deferiprone has been shown to reduce the total iron content in cells of the CNS; however, if doses are too high, the drug can actually worsen the symptoms of the disease

• Idebenone has significant effects in reducing the cardiac hypertrophy associated with the disorder; it shows only slight improvements with relation to its neurological symptoms when administered for an extended period of time.

• Histone deacetylase inhibitors try to counter epigenetic changes

• Through increasing preventing deacetylation and transition to methylation and silencing

• Nicotinamide and RG2833 have been shown to increase frataxin mRNA and protein levels

• Viral vectors aim to introduce FXN gene, shown to decrease oxidative stress and increase frataxin levels

References• Abrahão, A., Pedroso, J.L., Braga-Neto, P., Bor-Seng-Shu, U., de Carvalho Aguiar, P., Barsottini, O.G. (2015). Milestones in Friedreich ataxia: more than a century and still learning.

Neurogenetics. 16(3), 151-160.

• Acquaviva, Fabio, Imma Castaldo, Alessandro Filla, Manuela Giacchetti, Daniele Marmolino, Antonella Monticelli, Michele Pinelli, Francesco Saccà, and Sergio Cocozza. "Recombinant Human Erythropoietin Increases Frataxin Protein Expression Without Increasing MRNA Expression." Cerebellum The Cerebellum 7.3 (2008): 360-65. Web.

• Evans-Galea, Marguerite V., Alice Pébay, Mirella Dottori, Louise A. Corben, Sze Hwee Ong, Paul J. Lockhart, and Martin B. Delatycki. "Cell and Gene Therapy for Friedreich Ataxia: Progress to Date." Human Gene Therapy25.8 (2014): 684-93. Web.

• Gomez-Sebastian, Silvia, Alfredo Gimenez-Cassina, Javier Diaz-Nido, Filip Lim, and Richard Wade-Martins. "Infectious Delivery and Expression of a 135 Kb Human FRDA Genomic DNA Locus Complements Friedreich's Ataxia Deficiency in Human Cells." Mol Ther Molecular Therapy 15.2 (2007): 248-54. Web.

• Gottesfeld, Joel M., James R. Rusche, and Massimo Pandolfo. "Increasing frataxin gene expression with histone deacetylase inhibitors as a therapeutic approach for Friedreich's ataxia." Journal of neurochemistry 126.s1 (2013): 147-154.

• Libri, Vincenzo, et al. "Epigenetic and neurological effects and safety of high-dose nicotinamide in patients with Friedreich's ataxia: an exploratory, open-label, dose-escalation study." The Lancet 384.9942 (2014): 504-513.

• Liddell, J.R. (2015). Targeting mitochondrial metal dyshomeostasis for the treatment of neurodegeneration. Neurodegener Dis Manag. 5(4), 345-364.

• Lim, Filip, Gloria M. Palomo, Christina Mauritz, Alfredo Giménez-Cassina, Belen Illana, Francisco Wandosell, and Javier Díaz-Nido. "Functional Recovery in a Friedreich's Ataxia Mouse Model by Frataxin Gene Transfer Using an HSV-1 Amplicon Vector." Mol Ther Molecular Therapy (2007): n. pag. Web.

• Lynch, David R., and Kenneth H. Fischbeck. "Nicotinamide in Friedreich's ataxia: useful or not?." The Lancet 384.9942 (2014): 474-475.

• Mariotti, Caterina, Wolfgang Nachbauer, Marta Panzeri, Werner Poewe, Franco Taroni, and Sylvia Boesch. "Erythropoietin in Friedreich Ataxia."J. Neurochem. Journal of Neurochemistry 126 (2013): 80-87. Web.

• Nachbauer, Wolfgang, Sascha Hering, Markus Seifert, Hannes Steinkellner, Brigitte Sturm, Barbara Scheiber-Mojdehkar, Markus Reindl, Alexander Strasak, Werner Poewe, Guenter Weiss, and Sylvia Boesch. "Effects of Erythropoietin on Frataxin Levels and Mitochondrial Function in Friedreich Ataxia – a Dose–Response Trial." Cerebellum The Cerebellum 10.4 (2011): 763-69. Web.

• Pandolfo, M., Hausmann, L. (2013). Deferiprone for the treatment of Friedreich’s ataxia. J Neurochem. 126(1), 142-146.

• Parkinson, M.H., Schulz, J.B., and Giunti, P. (2013). Co-Enzyme Q10 and idebenone use in Friedreich’s ataxia. J Neurochem, 126(1), 125-141.

References (continued)• Soragni, Elisabetta, et al. "Epigenetic therapy for Friedreich ataxia." Annals of neurology 76.4 (2014): 489-508.

• Strawser, C.J., Schadt, K.A., Lynch, D.R. (2014). Therapeutic approaches for the treatment of Friedreich’s ataxia. Expert Rev Neurother. 14(8). 949-957.

• Sturm, Brigitte, Melissa Helminger, Hannes Steinkellner, Mohammad Mehdi Heidari, Hans Goldenberg, and Barbara Scheiber-Mojdehkar. "Carbamylated Erythropoietin Increases Frataxin Independent from the Erythropoietin Receptor." European Journal of Clinical Investigation40.6 (2010): 561-65. Web.