Scientific Research Report from euro-ATAXIA - May 2011

Several researchers took time out from their busy schedules at the scientific conference to give presentations about their current research to euro-ATAXIA. We are very grateful to all who contributed their time!

Annual update on EFACTS

Professor Massimo Pandolfo (Université Libre de Bruxelles, Brussels)
Professor Jörg Schulz (University Clinic, RWTH Aachen, Aachen Germany)

The European Friedreich’s Ataxia Consortium for Translational Studies (EFACTS) is a network of 14 partners from across Europe that is performing clinical and scientific research into Friedreich’s ataxia (FA). The project started in May 2010 and is funded by the European Commission.

Professor Pandolfo spoke about the scientific parts of the project and said that progress had been made with induced pluripotent stem (iPS) cells, which are created by reprogramming skin cells, or other cell types eg blood, to give them stem-cell like features, similar to cells from an embryo. These cells have now been developed into nerve and heart cells, the main cell types affected in FA, giving new models of FA which can be used to understand how FA occurs (the iPS cells maintain features of FA). They can also be used as systems in which to screen for new potential drugs. Professor Pandolfo said that research is uncovering more about the expression of the frataxin gene, the function of the frataxin protein and the way in which it interacts with other proteins and that these things should open up more therapeutic avenues in the future.

Professor Schulz works on the clinical side of the research and spoke about the FA patient database that is being created. It aims to enrol 600 people with FA over four years. Clinical data including scores from clinical rating scales will be collected and used to assess the natural progression of FA over time. The database is also hoped to provide a pool of potential people for future clinical trials. Biomaterials (eg blood or urine samples) will also be collected and stored for future analyses (eg to look for biomarkers or to use for other research). Dr Schulz explained that there will be a representative clinician (called a Principal Investigator), for each participating country, who will recruit patients and add them to the database, where their data will be anonymised to remove all identifying information such as date of birth, name etc. That way, all Principal Investigators can have access to the database without there being any concerns about patient confidentiality. Dr Schulz pointed out that this database differs from the one set up in the US by FARA, because the data will be added by clinicians rather than patients. He is keen to recruit people onto this database and encouraged people to contact their national ataxia organisation to register their interest. More information on e-facts and contact persons is available at www.efacts.eu. Furthermore you can subscribe for a newsletter at http://www.efacts.eu/html/studies/home/newsletter/subscribe.

Update on dominant ataxias

Dr Paola Giunti (National Hospital for Neurology and Neurosurgery, London) Dr Giunti spoke about the complexity of dominant ataxias and how increasing knowledge in this field is leading to increased challenges; over 30 different types of ADCA (Autosomal Dominant Cerebellar Ataxia) have been identified and the mutated genes have not been discovered for all of these conditions. Dr Giunti said that spinocerebellar ataxia type 6 (SCA6) is the most common ataxia in the UK and explained that because it has quite a slow progression and is not associated with many other symptoms, it was a useful ataxia to use for her Ataxia UK-funded research project looking at a possible physiotherapy intervention for spinocerebellar ataxia. The goals of the intervention were to improve functional, physical and quality of life measurements. All the data has now been collected and is awaiting publication.

Dr Giunti also spoke about her SCA11 research project which identified tau tubulin kinase II (TTBK2) mutations as the cause of SCA11 and investigated the effects of the mutations in cells and mice. The mutations were found by screening DNA from blood samples taken from people with SCA11 as well as healthy family members and comparing them. The mutated TTBK2 gene has been expressed in cultured cells, but no abnormalities have been found in investigations so far. In mice, mutated TTBK2 does not alter health or behaviour, although when the gene is completely deleted it is lethal. Mice with total and partially deleted TTBK genes are being used for further experiments aimed at understanding how the SCA11 mutations affect the function of TTBK2. Dr Giunti said that clinically, SCA11 is a rare ataxia with few associated symptoms, making it a ‘pure’ form of ataxia. It is also a very slowly progressive.

The role of frataxin and the development of cellular models

Dr Alain Martelli (IGBMC, Strasbourg)

Dr Martelli works in Dr Hélène Puccio’s lab and he described the group’s work towards improving cell models of FA and increasing understanding of the function of frataxin protein. As part of this work, the group has developed mouse models in which the frataxin gene can be deleted in certain parts of the animal’s body. (Total deletion of the frataxin gene is lethal but targeted removal of the gene from certain parts of the body is not, allowing the function of frataxin to be studied in these organs.) Mice with frataxin deleted from the heart or brain have FA-like features and have been relatively well characterised by the group, but ones with frataxin deleted from the liver or skeletal muscle, are newer models. Deletion of frataxin from the liver (important in regulation of iron levels) revealed that the primary role of frataxin is its involvement in the formation of iron sulphur cluster (ISC) proteins (complexes required for essential cell processes such as energy production, DNA and RNA metabolism, and iron metabolism). The group also established that although frataxin exists as monomers (single frataxin proteins on their own) and heteromers (groups of more than one frataxin protein joined together), its primary function is performed by the monomers.

Members of the lab have also been establishing induced pluripotent stem (iPS) cells from fibroblasts obtained from patients (see Dr Dottori’s summary for more information about iPS cells). The group has successfully created iPS cells and developed them into other cell types, namely heart (cardiac) cells and brain (neuronal) cells. Not only do these cells exhibit markers to show their new cell type (the heart cells even beat synchronously in the culture dish) but they also maintain the same genetic abnormalities as the original cells. This makes them good models of FA in which to examine the disease process in the lab and good tools in which to screen for potential new compounds for the treatment of FA. Developments on our understanding of disease mechanisms in FA and implications for therapy Dr Pierre Rustin (INSERM, Paris) Dr Rustin spoke about the theories for the consequences of reduced frataxin protein in Friedreich’s ataxia. The original theory, established some 14 years ago, was that frataxin loss caused a vicious cycle of oxidative damage, loss of iron sulphur cluster proteins and iron overload that led to cell dysfunction. However, Dr Rustin’s view is that the vicious cycle may only be seen at late stages of the condition. He proposed that decreased frataxin levels initially cause a sequence of events outlined in diagram below:

Increased sensitivity to oxidative stress --> Loss of iron sulphur cluster proteins --> Increased iron deposits and iron overload in mitochondria

Dr Rustin spoke briefly about his current research project, which is looking at the disruption of a particular signalling pathway in Friedreich’s ataxia and thanked the seven euro-ATAXIA member charities that are funding some of this work. The post doctoral researcher working on the project, Dr Aurélien Bayot, was also at the research conference.

Dr Rustin also spoke about the harlequin mouse model which has a naturally occurring genetic mutation in a gene other than frataxin but actually causes symptoms very similar to Friedreich’s ataxia in humans. When these mice were treated with different drugs, variable results were seen and Dr Rustin proposed this could be due to their complex genetic background and that the animals could be grouped into responders and non-responders. He drew parallels between these results and those from the recent idebenone clinical trials in humans. Despite the evidence not being strong enough to show conclusively that idebenone is beneficial in FA, there was also not sufficient evidence to prove that idebenone is ineffective either, and there have been anecdotal reports of benefits from people taking it. Dr Rustin’s feeling is that discovering the difference between responders and non-responders could allow the efficacy of the drug to be predicted and if this sort of information was available it could help inform clinical trials and promote approval of drugs in the future, even if for only a subset of patients.

Stem cell therapy research in FA

Dr Mirella Dottori (University of Melbourne, Australia) Dr Dottori spoke about the production of and uses for induced pluripotent stem (iPS) cells. IPS cells are cells with stem-cell like properties that have been created in the lab from cells taken from adult tissue, such as skin cells. She described how the addition of a cocktail of specific proteins to these skin cells grown in a dish can reverse their programming and turn them into cells with stem cell-like features, that is the ability to replicate and to become other types of cells. To date, Dr Dottori and her colleagues (including Dr Alice Pébay and Dr Paul Verma) have established two iPS cell lines using skin cells taken from two people with FA. These cells have also been treated in the lab to coax them towards becoming nerve and cardiac cells, the cell types most affected in FA. These cells have been shown to have the same genetic characteristics as the original FA skin cells, meaning that they can be used to study the underlying mechanism of FA in these cell types and to screen for potential future drugs.

Dr Dottori also gave a cautionary word about stem cell treatment clinics that are available in some countries. She pointed out that the procedures carried out in these clinics are unregulated and the claims made are often exaggerated and unproven. She stated that though promising, stem cell research is still at the stage of basic scientific research to understand the mechanisms and processes involved and advised exercising extreme caution with respect to the clinics until the treatments had been proven in clinical trials to be safe and beneficial.

HDAC inhibitors as potential future therapy for Friedreich's ataxia - latest update

Professor Joel Gottesfeld (Scripps Research Institute, California, US) Professor Gottesfeld explained how mutations in the frataxin gene (expanded GAA repeats) influence the chromatin structure (the way DNA is packaged within the cell), making it tightly packed into a conformation that cannot be read (heterochromatin) and causing the gene to be switched off. Histone deacetylase inhibitors prevent heterochromatin formation and help to switch the gene back on, hence their potential for a future FA therapy. Work in Professor Gottesfeld’s lab has been focussing on developing potential HDAC inhibitors for the treatment of FA. The most promising compound, known as 109, increases frataxin in two mouse models and in cells taken from people with FA. Professor Gottesfeld and his lab members have also successfully made iPS cells using the same methods as Dr Dottori’s lab and these have been successfully developed into nerve cells that replicate the gene silencing seen in FA and the associated biochemical abnormalities, such as deficient mitochondrial function. When these cells were treated with compound 109, increases in frataxin and improvements in mitochondrial function were seen. This is the first time that expression of a gene has been shown to improve mitochondrial function.

The pharmaceutical company, Repligen, has been carrying out preclinical studies on a range of HDAC inhibitors and compound 109 is the one showing most promise and therefore being taken forward as the ‘lead’ compound. New investigational drug applications have been filed with the Food and Drug Administration (FDA) in the US and with the European Medicines Agency (EMA) in Europe. A phase I safety trial to determine the safety and tolerability of 109 and its ability to increase frataxin levels in white blood cells is hoped to start in patients later this year at the San Luigi Hospital in Turin, Italy. In addition to this work, Dr Liz Soragni from Professor Gottesfeld’s lab (with funding from Ataxia UK and GoFAR) has been studying molecules generated by Repligen for improving compound 109 by making structural alterations that will increase the compound’s stability and brain penetrability.

Researching the cerebellum

Professor Chris Miall (University of Birmingham, UK and participant of the EC funded research network ‘C7 Cerebellar cortical control’) Cerebellar Cortical Control: Cells, Circuits, Computation and Clinic is a multinational group of researchers funded by the European Commission to study the function of the cerebellum and Professor Miall is part of this group. He said that although the cerebellum is small in volume compared to the rest of the brain, it accounts for approximately 30% of the overall area and 50% of the total number of nerve cells in the brain. It has a unique structure and function and is similar in structure between different vertebrate animals, suggesting an important and conserved role. He described the group’s experiments in animals, healthy volunteers, and patient participants where imaging was used to measure activity in different brain regions whilst performing tasks. These imaging studies showed activity in the cerebellum during movement and motor learning tasks. The cerebellum was found to be involved in hand/eye coordination and prediction of fine-tuned skilled movement. Continued cerebellar activity after completion of tasks was also seen, suggesting a role in the memory and learning processes associated with movement. Imaging studies have also shown cerebellar activity in emotional processing, working memory, language tasks and executive planning (the thinking processes involved in organizing thoughts, prioritizing tasks, making decisions and time management), suggesting a role in these processes. Future work will focus on how the cerebellum interacts with the cerebral cortex, its involvement in cognitive processes (such as awareness, reasoning, judging and learning) and how these processes are affected by cerebellar damage, eg in ataxia.

Update on the recessive ataxias

Professor Michel Koenig (IGBMC, Strasbourg)

Professor Koenig said recessively inherited forms of ataxia could manifest in various ways, including as metabolic ataxia, spastic ataxia, sensorimotor ataxias and congenital ataxia, ataxia with epilepsy and ataxia with mental retardation. The most common forms of recessive ataxia are Friedreich’s ataxia (FA), ataxia with vitamin E deficiency (AVED), ataxia telangiectasia (AT), autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS), and ataxia with oculomotor apraxia type 2 (AOA2). Dr Koenig’s research has identified a new type of recessive ataxia, called PHARC, in five Algerian families, which has been linked to chromosome 20. Symptoms include polyneuropathy (damage to nerves), hypoacousia (diminished hearing), ataxia, retinitis pigmentosa (visual loss caused by abnormalities in the retina) and cataracts. It is a slowly-progressive ataxia with an early age at onset. His work has also identified a new type of ataxia that is linked to chromosome 3. This condition has an age at onset of between 13 and 42 years old and is associated with severe cerebellar atrophy, brisk reflexes and eye movement problems. This condition is caused by mutations in the ANO10 gene. Dr Koenig described a third type of ataxia which has been found in one family from Saudi Arabia, Salih ataxia (SAA). There is an early age at onset, before seven years old, and epilepsy was seen in some young children at seven months old. A mutation was found in the KIAA0226 gene which encodes for a protein called rundataxin/rubicon. The mutation causes rundataxin to be located in the wrong parts of cells and this is thought to contribute towards the mechanism of degeneration in SAA.

Dr Koenig concluded his talk by highlighting the importance of high throughput sequencing technologies (next generation sequencing) for the improved diagnosis of the recessive ataxias; these new technologies will allow screening of larger numbers of genes than is presently offered. [See Ataxia UK website for details of a project testing high throughput sequencing in ataxia funded by Ataxia UK.]

Cerebellar ataxia clinical trials

Dr Francesco Saccá (Università degli Studi di Napoli ‘Federico II’, Naples) Dr Saccá focussed on the clinical trials for lithium in SCA1, SCA2 and multiple systems atrophy (MSA), all of which he has been involved with. Lithium is commonly prescribed for bipolar disorder, but a trial was started in people with SCA1 after improvements were seen with the drug in a mouse model of SCA1. The SCA1 clinical trial ended in February 2010, and the results have not yet been reported. The SCA2 trial will be a small (20 participants) placebo-controlled study looking at lithium treatment over a period of 48 weeks and will measure the safety and tolerability of the drug as well as looking at efficacy. The dose of lithium will be increased over the period of the trial in order to establish the optimum dose (as lithium can be toxic at high concentrations, any potential toxicity will be monitored carefully). One of lithium’s actions is to stimulate the cell’s system of degrading abnormal aggregations of protein within the cell and it is thought that this may be contributing towards the improvements seen in SCA1. A second specific action may be the reduction in Inositol-3-phosphate and in Ca2+ intracellular release, which is known to be increased in SCA2.

Other drugs currently in clinical trials for SCA are sodium phenylbutyrate (SCA3), varenicline (SCA3) and riluzole (hereditary cerebellar ataxias). Varenicline (trade name Chantix) is an anti-smoking medication and the clinical trial is assessing the safety and tolerability of the medication for a small number of people with SCA3. Riluzole is a drug that is prescribed for people with motor neurone disease and as it showed some small improvements in a small pilot study in people with chronic cerebellar ataxia, it is now being tested in a larger study looking at people with hereditary cerebellar ataxia.

Lithium is also being tested in a clinical trial for MSA. Other drugs currently in trials for MSA are fluoxetine, intravenous immunoglobulin, autologous mesenchymal stem cells, rifampicin and rasagiline.

Dr Saccá concluded by highlighting Good Clinical Practice (GCP), the importance of adhering to this procedure in all clinical trials and how non-profit clinical trials are organized in Italy. GCP provides guidelines for high quality clinical trials that involve humans and is based on internationally agreed standards of ethics and scientific quality. The European Medicines Agency (2006) says of GCP that, ‘compliance with this standard provides public assurance that the rights, safety and well-being of trial subjects are protected, consistent with the principles that have their origin in the Declaration of Helsinki, and that the clinical trial data are credible.’ Non-profit clinical trials (NPCT) are trials aimed at public interest with no clear profitable interest. Usually NPCTs are sponsored by an academic institution and not by a pharmaceutical company. No fees for ethical approval, insurance, visits, main diagnostic procedures, are requested. This makes the execution of NPCTs in Italy extremely easy and investments are only used for the remaining research procedures.

Update on idebenone trials in FA

Dr Will Andrews, Vice President, Medical Affairs, Santhera Pharmaceuticals

There have been three trials sponsored by Santhera testing the effect of idebenone in FA (two in the US and one in Europe) with a total of about 350 people (see report in Ataxian 171). While the first trial showed a statistically significant improvement in moderately affected FA patients taking idebenone compared to those taking placebo, these results were not replicated in the subsequent two studies. In Canada, the medical regulatory authorities granted conditional approval to Santhera’s idebenone product (Catena®) in July, 2008, for use in FA patients based on the first study, and pending results of further trials. Health Canada is currently reviewing a complete package of data from all the clinical studies completed to date. Dr Andrews explained that, currently, about half patients with FA in Canada have been prescribed idebenone. Santhera is committed to pursuing this further and has extended both the US trial and the European trial by 12 months to gain more information. During these extension studies, all participants are taking idebenone. The results from the 12 month US extension study combined with the six month original trial (ie total 18 months) were presented and showed that at the highest dose the ataxia rating scale values did not get worse, which is encouraging given FA is a progressive condition. This data is currently under review by Health Canada.

A new study has been recently started by Santhera, involving patients from the European extension study. This is a short, two month randomised withdrawal study, known as the PROTI study. This study involves people in the extension study being temporarily removed from the extension study to be enrolled in PROTI study and randomly assigned to either continue idebenone or to receive placebo in a blinded fashion (meaning that participants will not know whether they are taking idebenone or placebo). Their fatigue levels and speech will be assessed (anecdotally patients have reported benefits in these symptoms whilst taking idebenone), in addition to other neurological endpoints. In addition, patients will be asked to guess whether they think they have been taking idebenone or placebo, as a way of measuring if they feel the benefit. Santhera hopes that information gained from this study will help them to better understand FA and how idebenone helps FA patients feel and function better. This information will help Santhera in the design of new, larger clinical studies evaluating the potential benefit of idebenone in FA patients.

For more support or information please contact:

Ataxia UK, Lincoln House, Kennington Park, 1 – 3 Brixton Road. London SW9 6DE
Website: www.ataxia.org.uk.
Helpline: 0845 644 0606
Tel: +44 (0)20 7582 1444
Fax: +44 (0)20 7582 9444
Email: helpline@ataxia.org.uk.