Dimethyl fumarate dosing in humans increases frataxin expression: A potential therapy for Friedreich’s Ataxia

Mittal Jasoliya , Francesco Sacca , Sunil Sahdeo, Frederic Chedin, Chiara Pane, Vincenzo Brescia Morra, Alessandro Filla, Mark Pook, Gino Cortopassi. PLoS ONE 14(6): e0217776. doi:10.1371/journal.pone.0217776

Friedreich’s Ataxia (FA) is an inherited neurodegenerative disorder resulting from decreased expression of the mitochondrial protein frataxin, for which there is no approved therapy. High throughput screening of clinically used drugs identified Dimethyl fumarate (DMF) as protective in FA patient cells. Here we demonstrate that DMF significantly increases frataxin gene (FXN) expression in FA cell model, FA mouse model and in DMF treated humans. DMF also rescues mitochondrial biogenesis deficiency in FA-patient derived cell model. We further examined the mechanism of DMF's frataxin induction in FA patient cells. It has been shown that transcription-inhibitory R-loops form at GAA expansion mutations, thus decreasing FXN expression. In FA patient cells, we demonstrate that DMF significantly increases transcription initiation. As a potential consequence, we observe significant reduction in both R-loop formation and transcriptional pausing thereby significantly increasing FXN expression. Lastly, DMF dosed Multiple Sclerosis (MS) patients showed significant increase in FXN expression by ~85%. Since inherited deficiency in FXN is the primary cause of FA, and DMF is demonstrated to increase FXN expression in humans, DMF could be considered for Friedreich's therapy.

Efficient Electroporation of Neuronal Cells Using Synthetic Oligonucleotides: Identifying Duplex RNA and Antisense Oligonucleotide Activators of Human Frataxin Expression

Xiulong Shen, Sharon Beasley, Jennifer Putnam, Yanjie Li, Thahza Prakash, Frank Rigo, Marek Napierala, and David Corey. RNA rna.071290.119 Published in Advance May 31, 2019, doi:10.1261/rna.071290.119

We have previously shown that synthetic nucleic acids can activate FXN expression in human patient-derived fibroblast cells. We chose to further test these compounds in induced pluripotent stem cell-derived neuronal progenitor cells (iPSC-NPCs). Here we describe methods to deliver oligonucleotides and duplex RNAs into iPSC-NPC’s cells using electroporation. Activation of FXN expression is potent, easily reproducible, and potencies parallel those determined using patient-derived fibroblast cells. A duplex RNA and several antisense oligonucleotides with different combinations of 2’-methoxylethyl (2’-MOE), 2’-fluoro (2’-F), and constrained ethyl (cEt) were active, providing multiple starting points for further development and highlighting improved potency as an important goal for preclinical development. Our data support the conclusion that ASO-mediated activation of FXN is a feasible approach for treating FRDA and that electroporation is a robust method for introducing ASOs to modulate gene expressions in neuronal cells.

p53 Binds Preferentially to Non-B DNA Structures Formed by the Pyrimidine-Rich Strands of GAA·TTC Trinucleotide Repeats Associated with Friedreich’s Ataxia

Helma, R.; Bažantová, P.; Petr, M.; Adámik, M.; Renčiuk, D.; Tichý, V.; Pastuchová, A.; Soldánová, Z.; Pečinka, P.; Bowater, R.P.; Fojta, M.; Brázdová, M. . Molecules 2019, 24, 2078. doi: 10.3390/molecules24112078

In summary, we show that non-B DNA structures formed by TNR (TTC, GAA, CTG, CAG) and simple T-repeat are recognized by p53. Moreover, p53 prefers non-B DNA structures formed by the pyrimidine-rich strands of the investigated repetitive sequences and that the intact C-terminus is responsible for high p53 affinity to TNR non-B DNA structures. Further studies are needed to understand the precise function of p53 TNR non-B DNA recognition in relation to the development of Friedreich’s ataxia or other diseases coupled with TNR expansion.

Chondrial Therapeutics, Inc., the Bala Cynwyd-based biopharmaceutical company, has raised $25.8 million to develop treatment for mitochondrial disorders.

THE INQUIRER, phillynews.com. Sam Wood, Updated: May 23, 2019
Chondrial Therapeutics, Inc., the Bala Cynwyd-based biopharmaceutical company, has raised $25.8 million to develop treatment for mitochondrial disorders.
Chondria’s FA therapy has the much-coveted orphan drug designation from the FDA. Chondrial will file an Investigational New Drug application in the next couple of months and go into trials “almost immediately”.

Structure of the human frataxin-bound iron-sulfur cluster assembly complex provides insight into its activation mechanism

Nicholas G. Fox, Xiaodi Yu, Xidong Feng, Henry J. Bailey, Alain Martelli, Joseph F. Nabhan, Claire Strain-Damerell, Christine Bulawa, Wyatt W. Yue & Seungil Han; Nature Communications volume 10, Article number: 2210 (2019). doi:10.1038/s41467-019-09989-y

The core machinery for de novo biosynthesis of iron-sulfur clusters (ISC), located in the mitochondria matrix, is a five-protein complex containing the cysteine desulfurase NFS1 that is activated by frataxin (FXN), scaffold protein ISCU, accessory protein ISD11, and acyl-carrier protein ACP. Deficiency in FXN leads to the loss-of-function neurodegenerative disorder Friedreich’s ataxia (FRDA). Here the 3.2 Å resolution cryo-electron microscopy structure of the FXN-bound active human complex, containing two copies of the NFS1-ISD11-ACP-ISCU-FXN hetero-pentamer, delineates the interactions of FXN with other component proteins of the complex. FXN binds at the interface of two NFS1 and one ISCU subunits, modifying the local environment of a bound zinc ion that would otherwise inhibit NFS1 activity in complexes without FXN. Our structure reveals how FXN facilitates ISC production through stabilizing key loop conformations of NFS1 and ISCU at the protein–protein interfaces, and suggests how FRDA clinical mutations affect complex formation and FXN activation.

Peripapillary retinal nerve fibre layer thickness in Friedreich’s ataxia: a biomarker for trials?

Gilbert J Thomas-Black Micheal H Parkinson Fion Bremner Paola Giunti; Brain, awz117, doi:10.1093/brain/awz117

The results from this study show that OCT measurements of RNFL thickness have the potential to become a robust and objective biomarker for future treatment trials in FRDA.

Altered neocortical tactile but preserved auditory early change detection responses in Friedreich ataxia

Gilles Naeije, Vincent Wens, Mathieu Bourguignon, Serge Goldman, Massimo Pandolfo, Xavier De Tiège, Clinical Neurophysiology, 2019, ISSN 1388-2457, doi:10.1016/j.clinph.2019.05.003.

Evoked responses were detectable in all FRDA patients but one. In patients, TERs were delayed and reduced in amplitude, while AERs were only delayed. Only tactile MMN responses at the contralateral secondary somatosensory cortex were altered in FRDA patients. Maximal amplitudes of TERs, AERs and tactile MMN correlated with genotype, but did not correlate with clinical parameters.
In FRDA, the amplitude of tactile MMN responses at SII cortex are reduced and correlate with the genotype, while auditory MMN responses are not altered. Somatosensory pathways and tactile early change detection are selectively impaired in FRDA.

Characterization of human frataxin missense variants in cancer tissues

Maria Petrosino Alessandra Pasquo Leonore Novak Angelo Toto Stefano Gianni Elide Mantuano Liana Veneziano Velia Minicozzi Annalisa Pastore Rita Puglisi Emidio Capriotti Roberta Chiaraluce Valerio Consalvi; Hum Mutat. 2019 May 10. doi: 10.1002/humu.23789.

Defective function of frataxin may cause defects in mitochondria, leading to increased tumorigenesis. Tumour initiating cells show higher iron uptake, a decrease in iron storage and a reduced Fe‐S clusters synthesis and utilization. In this study we selected, from COSMIC database, the somatic human frataxin missense variants found in cancer tissues p.D104G, p.A107V, p.F109L, p.Y123S, p.S161I, p.W173C, p.S181F, and p.S202F to analyze the effect of the single amino acid substitutions on frataxin structure, function and stability. The spectral properties, the thermodynamic and the kinetic stability, as well as the molecular dynamics of the frataxin missense variants found in cancer tissues point to local changes confined to the environment of the mutated residues. The global fold of the variants is not altered by the amino acid substitutions, however some of the variants show a decreased stability and a decreased functional activity in comparison to that of the wild type protein.

Priorities when deciding on participation in early-phase gene therapy trials for Duchenne muscular dystrophy: a best–worst scaling experiment in caregivers and adult patients

Ryan S. Paquin, Ryan Fischer, Carol Mansfield, Brennan Mange, Katherine Beaverson, Annie Ganot, Amy Strong Martin, Carl Morris, Colin Rensch, Valeria Ricotti, Leo J. Russo, Alesia Sadosky, Edward C. Smith and Holly L.; Orphanet Journal of Rare Diseases 2019 14:102 doi:10.1186/s13023-019-1069-6

Several gene therapy trials for Duchenne muscular dystrophy initiated in 2018. Trial decision making is complicated by non-curative, time-limited benefits; the progressive, fatal course; and high unmet needs. Here, caregivers and patients prioritize factors influencing decision making regarding participation in early-phase gene therapy trials.

Objects used to construct choice sets for the best-worst choice experiment

Object	Description
Chance of improved muscle function	Data are positive about the chance of maintaining, and maybe improving, muscle function.
Chance of improved heart function	Data are positive about the chance of maintaining, and maybe improving, heart function.
Chance of improved lung function	Data are positive about the chance of maintaining, and maybe improving, lung function.
Benefit lasts about 10 years	Data suggest that gene therapy will last for 10 years. It may be shorter or longer, but no one knows. It is currently not possible to give a second dose of gene therapy. It may be possible in the future, but no one knows.
Chance of being in placebo group	The trial uses a placebo group, where some participants are randomly assigned to a group that gets an inactive (fake) treatment. People who get placebo during the trial would be eligible for gene therapy in the future.
Lowest dose may be too low for benefit	One of the trial’s goals is to test the right dose of gene therapy. If participants get a dose that is too low to work, they will not get another chance to use gene therapy.
Two muscle biopsies required	Being in the trial requires 2 muscle biopsies (one from the arm and one from the leg) to test for dystrophin production.
Not eligible for future trials	People who get gene therapy will most likely not be eligible for other clinical trials for the rest of their lives. It may someday be possible, but no one knows.
Limits later use of gene therapies or CRISPR	People who get gene therapy may not be able to use some newer types of gene therapy or gene editing (like CRISPR) for the rest of their lives. It may someday be possible, but no one knows.
Chance of long hospitalization	Data suggest a low risk of needing a long hospitalization of 4 weeks or more to recover from serious side effects.
Chance of death (low risk)	Data suggest a very low risk of death soon after using gene therapy. That risk should be even lower than we showed you in the first survey task.

Orphan designation was granted by the European Commission to Takeda Pharma for TAK-831for the treatment of Friedreich’s ataxia

On 1 April 2019, orphan designation (EU/3/19/2148) was granted by the European Commission to Takeda Pharma A/S, Denmark, for 4-hydroxy-6-{2-[4-(trifluoromethyl)phenyl]ethyl}pyridazin-3(2H)-one (also known as TAK-831) for the treatment of Friedreich’s ataxia.

First published: 07/05/2019
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