Dr. Timothy Barrett’s Update | University of Birmingham, United Kingdom

Dear friends and colleagues,

I hope everyone is keeping OK. I have 3 items to update you on.

Firstly, the TREATWOLFRAM trial is continuing to progress well. We had an independent Data Monitoring Committee meeting in January. This is chaired by Professor Karen Morrison, an honorary consultant in adult neurology, who previously led the highly specialised service for adults with Wolfram syndrome. The Data Monitoring Committee reviewed the unblinded data. I am pleased to say that they had no safety concerns, and were happy for the trial to continue to completion. Following this meeting, our Trial Steering Committee met, chaired by Professor Marc Peschanski, Director of INSERM, a large research institute outside Paris. We discussed the trial progress so far, and plans for acting on the results at the end of the trial. The last participant will complete the trial at the end of October 2024. We will then have 2-3 months to collect any outstanding data from study sites. The Clinical Trials Unit…..
read in full here.

Dr. Fumihiko Urano Washington University School of Medicine, USA

Dr. Fumihiko Urano

Washington University School of Medicine, USA

Dear Friends,

 

I want to take a moment to express my deep gratitude for your unwavering belief in and support of our mission to find a cure for Wolfram syndrome. Your enduring encouragement has been a beacon of hope guiding us on this remarkable journey. As we embark on the year 2024, filled with hope and determination to inch closer to our goal of finding a cure, I would like to provide a summary of our progress in the battle against Wolfram syndrome.

 

Rare Disease Day at NIH 2024

Before I delve into our progress update, I’m excited to share some fantastic news with you. I’ve received an invitation to present our research on Wolfram Syndrome at the Rare Disease Day event held at the National Institutes of Health on February 29, 2024. This event is widely regarded as one of the most prestigious gatherings for rare diseases, offering an excellent platform for us to raise awareness about Wolfram Syndrome. Even if you can’t attend in person, you can still participate by watching my presentation remotely. Here is the link to access it: https://ncats.nih.gov/news-events/events/rdd

 

Ongoing clinical trial

In partnership with Amylyx Pharmaceuticals, we are actively advancing the development of AMX0035, an innovative oral medication designed to slow or halt the progression of Wolfram syndrome. In 2020, the US FDA granted AMX0035 orphan drug status for Wolfram syndrome. Using data from previous clinical studies, we have developed a protocol to assess the safety and effectiveness of AMX0035. This protocol has been approved by both the US FDA and the Institutional Review Board at Washington University Medical Center. We have initiated a phase 2 clinical trial for adult patients with Wolfram syndrome at Washington University Medical Center, with the first participant starting AMX0035 treatment in April 2023.

 

Our trial is proceeding smoothly, and we are currently planning our next steps. We have received numerous inquiries about including children in the trial, as well as patients without diabetes and patients with WFS1-related disorders (those who have hearing loss and optic nerve atrophy due to having one pathogenic copy of WFS1). We appreciate your interest and feedback, and we plan to make a formal announcement later this year. Please stay tuned for further updates.

 

Regenerative Therapy for Optic Nerve Atrophy

Our primary objective is to halt and reverse the progression of low vision resulting from optic nerve atrophy in individuals with Wolfram syndrome. We are pursuing this goal through regenerative medicine. Our current strategy involves the administration of a regenerative factor called MANF into the eyes of Wolfram syndrome patients using a viral vector. As you may be aware, our brain naturally produces certain neurotrophic factors like BDNF and CDNF to maintain brain health. MANF is also a neurotrophic factor, but it stands out because it offers protection against Endoplasmic Reticulum (ER) stress, a key molecular mechanism involved in Wolfram syndrome. Additionally, MANF aids in boosting the growth of ER-stressed cells. We are presently conducting preclinical studies using cell and rodent models specifically designed to mimic Wolfram syndrome, in order to evaluate the effectiveness of MANF in addressing optic nerve atrophy. Promising results have emerged from our humanized mouse model of Wolfram syndrome, indicating the potential of this innovative approach to treat other causes of low vision as well. While there are undoubtedly several challenges ahead, our ultimate aim is to initiate a regenerative therapy trial for optic nerve atrophy within the next 3 to 7 years.

 

Gene Editing Therapy

The primary cause of Wolfram syndrome stems from a pathogenic alteration within the WFS1 gene. Consequently, the most effective approach to treating Wolfram syndrome involves rectifying these gene mutations. To ensure safety, we have transitioned from using CRISPR to utilizing the more advanced Base Editing (2nd generation) and Prime Editing (3rd generation) techniques to correct the pathogenic changes in the WFS1 gene associated with Wolfram syndrome. These cutting-edge gene editing technologies are currently considered the most advanced methods available. To evaluate the efficacy of this technology, we have generated rodent models featuring pathogenic mutations in the Wfs1 gene that closely mimic those observed in our patients. Our ultimate objective is to apply this therapeutic approach to benefit our patients within the next 5-10 years.

 

International Consortium

I’d like to present a significant idea to you. After extensive thought and discussions with senior advisers, I’ve made the decision to establish an international consortium focused on Wolfram Syndrome and Related Disorders and join the Rare Diseases Clinical Research Network (https://www.rarediseasesnetwork.org/). I intend to submit a substantial grant application to the National Institutes of Health. Through this consortium, my goals are as follows. I’m pleased to share that The Snow Foundation has graciously agreed to lead the patient organization group for objective #4.

1. Advance our understanding of the clinical manifestations of Wolfram syndrome and related disorders through collaborative clinical research.

2. Collaboratively create thorough clinical guidelines.

3. Investigate genotype-phenotype correlations and identify drug targets.

4. Improve awareness among scientists, physicians, and the general public regarding the unique needs of patients with Wolfram syndrome and related disorders with patient organizations.

 

Clinical service

To improve the clinical care for patients with Wolfram syndrome and WFS1-related disorders, including WFS1-related deafness and optic nerve atrophy, we have been running the WFS1 clinic at the Center for Advanced Medicine, Washington University Medical Center. This clinic has been successful, and I see patients from different states and countries almost every week. I appreciate that the Snow Foundation, the Ellie White Foundation, the Unravel Wolfram Syndrome, and the FB groups related to Wolfram syndrome have referred patients to our clinic. We offer genetic evaluations, education, and counseling for patients and family members of all ages with or suspected to have Wolfram syndrome and WFS1-related disorders. We also provide personalized management plans with other specialists at our medical center and beyond. We accept international patients via our international patient care office. We also accept out-of-state patients.

 

Patients in the US

If you’re in the US, please call Christine Manning, RN, Nurse Coordinator, at 314-747-7055 or 314-362-3500. Let her know that you or your family member has Wolfram syndrome or WFS1-related medical conditions and need to make an appointment. Once we review your medical records, Dr. Urano or his staff will contact you to discuss which specialists you may need to see.

 

Sending Medical Records via Fax

Please fax your medical records to 314-747-7065.

 

Referrals via Fax for both Missouri patients and out-of-state patients

Please fax your referral request to 314-747-7065.

 

International Patients

International patients are welcome to contact our international patient care office to schedule an appointment by calling +1-314-273-3780 or sending an email to Internationalpatients@wustl.edu.

 

Conclusion

The encouraging outcomes we’ve witnessed fill us with hope for the future, and we’re dedicated to forging ahead in our mission to bring about meaningful change. Thank you again for your unwavering support. Together, we will persist in our efforts and shine a beacon of hope for those affected by Wolfram syndrome. Here’s to a brighter future on the horizon!

 

With grace and gratitude,

Fumi

 

Fumihiko Urano, MD, PhD, FACMG

Professor of Medicine and of Pathology & Immunology

Samuel E. Schechter Endowed Professor in Medicine

Director, Wolfram Syndrome/WFS1-related disorders Registry & Clinical Study and WFS1 clinic at BJC HealthCare

Washington University School of Medicine

https://wolframsyndrome.wustl.edu/

Dr. Vania Broccoli
San Raffaele Hospital/CNR-Institute of Neuroscience in Milan, Italy.
Eye gene therapy for restoring WFS1 gene function in Wolfram mice
AAV-based gene therapy is based on intra-vitreal injections of AAV vector expressing a therapeutic gene. This strategy is already in clinical use for treating Leber hereditary optic neuropathy (LHON) and clinical trials performed in multiple centers have reached beneficial effects without any troublesome side-effects. Strong advantages of this approach areå the ease of the surgical intervention, the efficacy of the AAV infection and the durable expression of the therapeutic genes for many years if not forever. Thus, we are developing an AAV-based replacement gene therapy to express a functional copy of the Wfs1 in retinal tissue to eb tested in Wolfram mice. However, our recent results indicate that Wolframin is significantly more expressed in glial cells where it controls MCT1 protein levels and its inactivation leads to RGC death through a non-cell autonomous mechanism of energy deprivation. These results clearly implicate that restoring Wfs1 gene expression only in RGCs might not be sufficient to protect from progressive visual loss. Our previous results indicate that both astrocytes in the retina and oligodendrocytes in the optic nerve play a crucial role in supplying energetic molecules to RGCs and this function is affected when Wolframin is inactivate in these cells. Thus, the question is in which cells the reintroduction of Wfs1 will have the best therapeutic effects in promoting RGC survival and functions. To answer to this question and to establish the most efficient strategy of gene therapy, we have been generating 4 different AAV vectors where the WFS1 gene is under the control of different promoters that combined with a specific delivery route will allow the expression of the therapeutic WFS1 gene copy in either only RGCs, optic nerve oligodendrocytes, retinal astrocytes, both glial cell types or all these type together. We will produce in our lab the AAV viral particles for intra-vitreal injections in the Wolfram mice.
This study will determine the best AAV gene therapy method considering both the ease of the administration route and its beneficial effects on visual functions. These results will pave the way to the clinical exploitation of this approach in Wolfram patients for establishing the first neuroprotective approach to arrest RGC loss in the disease.

2024 Support Drive, Could you help?

This year, we are funding four projects worth almost $400,000.
Please donate today to support our community. Your gift will make a significant difference and help us achieve our goal.
Please read below to learn about our projects.

Donate

1. Novel experimental therapies to treat blindness in Wolfram syndrome- Eye gene therapy for restoring WFS1 gene function in Wolfram mice

Dr. Vania Broccoli
San Raffaele Hospital/CNR-Institute of Neuroscience, Milan Italy

Eye gene therapy for restoring WFS1 gene function in Wolfram mice

AAV-based gene therapy is based on intra-vitreal injections of AAV vector expressing a therapeutic gene. This strategy is already in clinical use for treating Leber hereditary optic neuropathy (LHON) and clinical trials performed in multiple centers have reached beneficial effects without any troublesome side-effects. Strong advantages of this approach areå the ease of the surgical intervention, the efficacy of the AAV infection and the durable expression of the therapeutic genes for many years if not forever. Thus, we are developing an AAV-based replacement gene therapy to express a functional copy of the Wfs1 in retinal tissue to eb tested in Wolfram mice. However, our recent results indicate that Wolframin is significantly more expressed in glial cells where it controls MCT1 protein levels and its inactivation leads to RGC death through a non-cell autonomous mechanism of energy deprivation. These results clearly implicate that restoring Wfs1 gene expression only in RGCs might not be sufficient to protect from progressive visual loss. Our previous results indicate that both astrocytes in the retina and oligodendrocytes in the optic nerve play a crucial role in supplying energetic molecules to RGCs and this function is affected when Wolframin is inactivate in these cells. Thus, the question is in which cells the reintroduction of Wfs1 will have the best therapeutic effects in promoting RGC survival and functions. To answer to this question and to establish the most efficient strategy of gene therapy, we have been generating 4 different AAV vectors where the WFS1 gene is under the control of different promoters that combined with a specific delivery route will allow the expression of the therapeutic WFS1 gene copy in either only RGCs, optic nerve oligodendrocytes, retinal astrocytes, both glial cell types or all these type together. We will produce in our lab the AAV viral particles for intra-vitreal injections in the Wolfram mice.

This study will determine the best AAV gene therapy method considering both the ease of the administration route and its beneficial effects on visual functions. These results will pave the way to the clinical exploitation of this approach in Wolfram patients for establishing the first neuroprotective approach to arrest RGC loss in the disease.

Donate

 

2. Wolframin Protein Project

Understanding the molecular role of WFS1
and how mutations in this protein cause Wolfram syndrome.

Filippo Mancia, Ph.D. Columbia University, USA
Dr. Rosemary Cater, University of Queensland, Australia
Wolfram syndrome manifests as a genetic disorder marked by early-onset diabetes, progressive optic atrophy, and hearing loss. In addition to these defining symptoms, some individuals may also experience neurological complications, including motor impairments, neurological disorders, and deficits in memory and learning. Tragically, Wolfram syndrome carries a high mortality rate, and currently, there are no therapeutic interventions available to halt or slow its progression. This lack of effective treatment stems, in part, from our incomplete understanding of the disease’s underlying mechanisms.While it is known that Wolfram syndrome is caused by mutations in the WFS1 gene, the precise role of the WFS1 protein in healthy individuals remains elusive, as does the link between its various mutations and Wolfram Syndrome. Our research is focused on understanding the molecular function of the protein encoded by WFS1, and what this protein looks like on an atomic level. By gaining these molecular insights into the normal WFS1 protein, we will be able to understand how mutations in this protein disrupt its activity and cause Wolfram syndrome.Through a collaborative effort with Prof Vania Broccoli (San Raffaele Hospital and CNR-Institute of Neuroscience in Milan) and Prof Filippo Mancia (Columbia University, USA), we have preliminary results that are already helping us understand what this protein looks like and are enthusiastic about furthering this research to fill this gap in knowledge within the field, and ultimately contribute to the development of effective treatments for Wolfram syndrome.

Donate

3. Mario Plaas

University of Tartu, Estonia

Our primary focus is to discover preclinical Liraglutide and other GLP1 receptor agonists available on the market to help slow the progression of Wolfram syndrome. Additionally, we are exploring a new generation of GLP1 and GIP co-agonists for the same reason. We are also developing gene therapy against WS-associated neurodegeneration.

Donate

 

4. 2024 International Research Symposium
Windsor, England

The Wolfram Syndrome International Symposium, an event facilitating collaborative efforts to advance medical knowledge for over 13 years, is all set to take place from October 22-24, 2024, in Windsor, England. This invite-only conference, hosted by The Snow Foundation and Wolfram Syndrome UK, is expected to be attended by over 35 leading research scientists. These meetings have proved indispensable in driving medical advancement, improving patient care, and developing new treatments and therapies for patients afflicted with Wolfram syndrome.

Donate

National Research Council of Italy: Project application

Title: Novel experimental therapies to treat blindness in Wolfram syndrome
Applicant: Dr. Vania Broccoli

San Raffaele Hospital/CNR-Institute of Neuroscience, Milan Italy

Eye gene therapy for restoring WFS1 gene function in Wolfram mice

AAV-based gene therapy is based on intra-vitreal injections of AAV vector expressing a therapeutic gene. This strategy is already in clinical use for treating Leber hereditary optic neuropathy (LHON) and clinical trials performed in multiple centres have reaches beneficial effects without any troublesome side-effects. Strong advantages of this approach areå the ease of the surgical intervention, the efficacy of the AAV infection and the durable expression of the therapeutic genes for many years if not forever. Thus, we are developing an AAV-based replacement gene therapy to express a functional copy of the Wfs1 in retinal tissue to eb tested in Wolfram mice. However, our recent results indicate that Wolframin is significantly more expressed in glial cells where it controls MCT1 protein levels and its inactivation leads to RGC death through a non-cell autonomous mechanism of energy deprivation. These results clearly implicate that restoring Wfs1 gene expression only in RGCs might not be sufficient to protect from progressive visual loss. Our previous results indicate that both astrocytes in the retina and oligodendrocytes in the optic nerve play a crucial role in supplying energetic molecules to RGCs and this function is affected when Wolframin is inactivate in these cells. Thus, the question is in which cells the reintroduction of Wfs1 will have the best therapeutic effects in promoting RGC survival and functions. To answer to this question and to establish the most efficient strategy of gene therapy, we have been generating 4 different AAV vectors where the WFS1 gene is under the control of different promoters that combined with a specific delivery route will allow the expression of the therapeutic WFS1 gene copy in either only RGCs, optic nerve oligodendrocytes, retinal astrocytes, both glial cell types or all these type together. We will produce in our lab the AAV viral particles for intra-vitreal injections in the Wolfram mice. Six groups of mice will be prepared (4 animals for each group) to be treated each group with a different AAV vector at 2 months of age. Then, treated mice will be subjected to the visual acuity test (Optodrum machine) every 2 months. After 10 months from the treatment, the eyes will be isolated and analyzed for retinal morphology, RGC numbers and optic nerve anatomy by electron microscopy. This analysis will define in which cell type is most relevant to express the WFS1 functional gene copy to obtain the best protection of visual functions in Wolfram mice.

Although we expect that the AAV supporting the expression of WFS1 in both RGC and glial cells will provide the most beneficial effects, it is possible that WFS1 expression only in retinal astrocytes will trigger significant improvements. In that case, this last option might be preferable given that it might be easier to transduce glial cells respect to RGCs in the retina with AAV particles. This study will determine the best AAV gene therapy method considering both the ease of the administration route and its beneficial effects on visual functions. These results will pave the way to the clinical exploitation of this approach in Wolfram patients for establishing the first neuroprotective approach to arrest RGC loss in the disease.

Timeline

Dr. Vania Broccoli, Project application timeline

Understanding the molecular role of WFS1 and how mutations in this protein cause Wolfram syndrome.

Wolfram syndrome manifests as a genetic disorder marked by early-onset diabetes, progressive optic atrophy, and hearing loss. In addition to these defining symptoms, some individuals may also experience neurological complications, including motor impairments, neurological disorders, and deficits in memory and learning. Tragically, Wolfram syndrome carries a high mortality rate, and currently, there are no therapeutic interventions available to halt or slow its progression. This lack of effective treatment stems, in part, from our incomplete understanding of the disease’s underlying mechanisms.

While it is known that Wolfram syndrome is caused by mutations in the WFS1 gene, the precise role of the WFS1 protein in healthy individuals remains elusive, as does the link between its various mutations and Wolfram Syndrome. Our research is focused on understanding the molecular function of the protein encoded by WFS1, and what this protein looks like on an atomic level. By gaining these molecular insights into the normal WFS1 protein, we will be able to understand how mutations in this protein disrupt its activity and cause Wolfram syndrome.

Through a collaborative effort with Prof Vania Broccoli (San Raffaele Hospital and CNR-Institute of Neuroscience in Milan) and Prof Filippo Mancia (Columbia University, USA), we have preliminary results that are already helping us understand what this protein looks like and are enthusiastic about furthering this research to fill this gap in knowledge within the field, and ultimately contribute to the development of effective treatments for Wolfram syndrome.

The Neural Circuit Development and Regeneration research group at the University of Leuven (Biology Department, KU Leuven, Belgium), led by Prof. L. Moons and Dr. Lies De Groef, aims to define the cellular and molecular mechanisms underlying neurodegeneration, -inflammation and -regeneration in the injured, diseased or aged central nervous system. Within their research, they focus on the inter-relatedness of neurobiology and ophthalmology research, and position the eye ‘as a window to the brain’. Besides glaucoma, Alzheimer’s and Parkinson’s disease, they have a major interest in Wolfram syndrome. Via ocular and MRI imaging, electrophysiology and visual function testing in laboratory animals, they try to unravel the impact of Wolfram syndrome on the retina and visual system and understand the underlying disease mechanisms. Their studies in a Wolfram mouse model (Wfs1Δexon8) revealed progressive vision loss, neuronal dysfunction and neuroinflammation in the retina, and axonal conduction defects in the optic nerve. Based on these findings and their special interest in the role of glial cells (oligodendrocytes, micro- and astroglia) in the pathogenesis of Wolfram syndrome, they are further complementing this work with mechanistic studies in patient iPSC-derived cells (in collaboration with Prof. C. Verfaillie and G. Bultynck, KU Leuven). Furthermore, building on their expertise in visual system phenotyping, the Neural Circuit Development and Regeneration research group is also evaluating the effect of novel therapeutics to prevent blindness, including preclinical studies with GLP-1 analogues (in collaboration with M. Igoillo Esteve, Université Libre de Bruxelles) and gene editing approaches (in collaboration with C. Verfaillie).

Our team’s goal is to discover, test and develop treatments in order to prevent or limit visual impairment and to improve the autonomy and the quality of life of patients with Wolfram syndrome.

Update March 5, 2024:

Recently we have identified a family of molecules with the capacity to significantly stimulate the growth of retinal ganglion cells in vitro in a model of optic atrophy. We developed a zebrafish model with an optic atrophy and we have treated these fishes with one of these molecules. We used increasing doses of molecules to measure the toxicity and determine the most effective dose to protect the optic nerve. We have determined the dose with the best effect and confirmed that treatment with this molecule can prevent optic nerve developmental delay in vivo in our model of optic neuropathy. We are studying the mechanism of action of this molecule and using it in several model of Wolfram syndrome. We look forward to a clear indication of the possibility of using this molecule in the future development of a treatment for Wolfram syndrome.

Gene therapy projects using WFS1 are also important for us. We have synthesized a novel AAV2/9-WFS1 vector to treat all affected tissues in a previously established mouse model of Wolfram syndrome. After injection of the vector in young mice, we have checked that the vector could transduce all affected tissues including, eye, ear, brain and pancreas. We are now evaluating the efficacy of this gene transfer on the visual and auditory function of our mouse model.

Update May 26, 2023:

Development of a novel molecule to treat optic atrophy in Wolfram syndrome

Wolfram syndrome is a devastating multisystemic disorder and despite decades of intense research, no curative therapies are currently available. All aspects of this disease reinforce our commitment to elaborate a therapeutic strategy for Wolfram patients.

We have identified a molecule with the capacity to stimulate significantly the growth of retinal ganglion cells in vitro in a model of optic atrophy. This molecule appears to represent interesting therapeutic candidate for the disease. We have generated a zebrafish model reproducing an optic atrophy similar to that observed in wolfram syndrome. In this model we show a decrease of optic nerve volume and retinal ganglion cell number, and a decrease of visual motor response. To obtain information on whether our molecule could be used in the future development of a treatment for Wolfram syndrome we have treated our optic atrophy zebrafish model. Very interestingly our preliminary results show a significant protection of the optic nerve from degeneration in early stage in the treated model. Our project is now to study the mechanism of action of this molecule and use it in several model of Wolfram syndrome. These results can raise the interesting possibility of a future therapy.

Update October 9, 2020:

For the last 20 years, our group together with Pr Christian Hamel has made highly significant contributions concerning the clinics, genetics and pathophysiology of autosomal inherited optic neuropathies, by identifying the genes involved in these diseases, analyzing mouse models reproducing human pathologic mutations, deciphering the basic function of the uncharacterized genes and start therapy projects in this field.

Wolfram syndrome is a devastating multisystemic disorder and despite decades of intense research, no curative therapies are currently available. All aspects of this disease reinforce our commitment to elaborate a therapeutic strategy for Wolfram patients.

Our team are working on two axes:

  1. Development and testing of new therapeutic drugs
  2. Use gene therapy delivering WFS1 to treat Wolfram syndrome

Recently we have identified a family of molecules with the capacity to stimulate significantly the growth of retinal ganglion cells in vitro in a model of optic atrophy. These molecules appear to represent interesting therapeutic candidates for the disease. Our project is to test the efficacy of these molecules in a previously established mouse model of Wolfram syndrome.

Gene therapy has exciting potential. For several reasons, gene therapy will have considerable therapeutic potential in this monogenic disorder. In our first gene therapy
studies in a mouse model of Wolfram syndrome, we have demonstrated that it is possible to rescue visual function using overexpression of WFS1 when it is administrated into the
vitreous. To go further, we hypothesized that a systemic delivery of WFS1 could restore WFS1 expression and function in both retinal ganglion cells and other organs. Our project will evaluate functional evidence that WFS1 expression by systemic gene transfer in a Wolfram model greatly mitigates the development of the phenotype.

Our projects represent a first step in acquiring the proof of principle necessary for carrying out clinical trial in human. Our link with the reference center for genetic sensory diseases Maolya in Montpellier will help us to improve preclinical to clinical translation.

 

Cécile Delettre
Neuropathies Optiques Héréditaires et Déficits Mitochondriaux
Inherited Optic Neuropathies and Mitochondrial Disorders
INSERM U 1051 – Pathologies sensorielles, Neuroplasticité et Thérapies
Institut des Neurosciences de Montpellier
Hôpital Saint Eloi, 80 rue Augustin Fliche
BP74103, 34091 MONTPELLIER Cedex 5
Tel: (33/0) 499 63 60 30 Fax: (33/0) 499 63 60 20

http://www.inmfrance.com

Washington University School Of Medicine

The study of liraglutide (Victoza) in Wolfram Syndrome that is being conducted by Drs. White and Marshall at Washington University has gotten off to a slow start because of the COVID-19 pandemic. However, they have now recruited 10 subjects who are in various stages of recruitment, screening or treatment.  Two have already started treatment and eight more should be starting soon.  If you are interested in participating, please contact Dr. White (white_n@wustl.edu or 314-286-1156) or Dr. Marshall (bmarshall@wustl.edu).

Catholic University of Leuven, Belgium

Genome editing for Wolfram syndrome:

Although rare individually, genetic disorders collectively constitute a common health problem. As the cause of these diseases is a defective gene, gene therapy would be able to resolve all of these disorders. Wolfram syndrome is a genetic disorder, with the ultimate symptoms of Diabetes, blindness and deafness in young kids. The most recent method of gene therapy is gene editing. Gene editing is repairing the defect of the gene by using molecular scissors such as CRISPR/Cas9. CRISPR/Cas9, which is the most commonly used type of this system is, composed of two components Cas9 protein which can make a cleavage in DNA and a guide RNA that is a RNA molecule which binds to Cas9 and guide it towards a specific target sequence of 20 bases. CRISPR/Cas9 allows us to cut the human genome by generating DNA double-strand breaks (DSB) close to the mutation. Such DSB is sensed by two main cellular repair pathways, nonhomologous end-joining (NHEJ) and homology-directed repair (HDR). While NHEJ is generally known to be an error-prone pathway causing insertions and deletions (indels) of DNA bases, which occurs independently of a repair template, HDR relies on the presence of a repair template to refill the correct bases and is considered an error-free pathway. Therefore, HDR has been extensively tested and used for precise gene editing.  Given that HDR is restricted to the S and G2 phases of the cell cycle, only present in dividing cells, this approach might not be suitable for editing and repairing the genome in non-dividing cells. However many of monogenic disorders, including Wolfram syndrome cause disease, because the function of terminally differentiated non-dividing cells in different organs is impaired. Therefore, to reverse the defect caused by monogenic diseases, therapies that can correct the genetic defect in non-dividing cells are required. One very recent tool that is made based on CRISPR/Cas9 system is called Base editor. Base editing is a direct replacement of a single DNA base with the correct one without making a DSB and therefore not relying on HDR. Base editor (BE) is an engineered fusion enzyme consist of Cas9 and cytidine deaminase (CD) that enables a C-G to T-A conversion in an activity window that can be as narrow as 1-2 bases. Since the initial description, BE has been extensively improved and expanded. Another important base editing tool is adenine base editors (ABEs) contains a DNA adenosine deaminase instead of CD and enables a T-A to C-G transition. ABE is a major milestone in base editing considering that the target mutations (C-G to T-A ) account for half of the pathogenic known point mutations in human. Some of the mutations causing wolfram syndrome are targetable by ABE (e.g. c.2002 C>T or c.1620 G>A). ABE has been proven effective in mice on different non-dividing cell types including the cells in retina. However, due to differences between mice and human in many aspects and specifically on DNA repair system, before moving forward to clinical application of ABE, it is important to evaluate this tool on human cells in vitro (in a dish). Therefore, in our study we are planning to evaluate the efficiency of ABE on human derived non-dividing cells. Since these cells are not accessible from human, we will generate them in the lab from Wolfram patient derived stem cells. We are focused on two cell types; oligodendrocytes and retinal ganglion cells as two non-dividing cells leading to eye and brain related symptoms of Wolfram syndrome. We successfully differentiated our patient derived stem cells to oligodendrocytes and retinal ganglion cells. Next, we tested the efficiency of the ABE tool on the stem cells of patients to confirm that the tool is generated correctly. Our result showed highly efficient correction of the mutated DNA base in the stem cells of patients (around 90%). Therefore, we proceed with making delivery vectors to be able to get the ABE tool to oligodendrocyte and retinal ganglion cells. Our vectors are successfully generated, and we are currently performing delivery of the tools to our target cells. We hope to release the result of this part in near future.

Catherine Verfaille