The myotonic dystrophy (DM) community has a strong champion in singer-songwriter Eric Hutchinson. As part of his long-time efforts to support Care and a Cure for myotonic dystrophy, Eric is offering one-of-a-kind fan activities and memorabilia in a new pledge campaign, and a portion of the proceeds will be donated to MDF. Eric is offering private concerts for you and your guests as part of the pledge campaign, a deluxe edition of his album Easy Street, a signed and personalized acoustic guitar, framed lyrics and the opportunity to have a private tour of New York City with him, among other items. The pledge campaign ends on December 31, 2016.

"I’m thrilled to announce the Deluxe Edition of my latest album, Easy Street!" said Eric. "I recently learned about PledgeMusic.com and thought it sounded like a fantastic way to share some of my time, new music and some special memorabilia with all of you. Plus, for the first time ever, ‘Easy Street’ is available on VINYL, the first time ANY of my albums has been on wax. I’ve spent a lot of 2016 educating people about myotonic dystrophy, a condition that has affected my dad and my family for a long time. Part of the proceeds from this PledgeMusic campaign will go to support MDF and myotonic dystrophy research.

"I know firsthand what living with myotonic dystrophy looks like for a loved one and his or her caregivers. I'm committed to helping to find care and a cure for DM and I hope you'll join me. I want to thank MDF for helping my family better understand myotonic dystrophy and letting us know that we’re not alone in living with this disease. I’m donating to MDF because it’s important to provide resources and support to families, and accelerate efforts to find a therapy."

Eric’s commitment to support the DM community is driven by his own personal connection to the disease: His father has DM, and for years Eric lived with fear and uncertainty about his own status. Eric wrote about his family connection to myotonic dystrophy this year in a heartfelt personal essay.

The multi-system involvement and heterogeneity that characterize myotonic dystrophy (DM) have fostered several efforts to design patient-reported outcome measures (PROMs) for clinical studies and trials. The intent of PROMs is to use patient feedback in design and implementation of validated questionnaires that can simultaneously capture changes across the challenging symptomology of DM while obtaining clinically meaningful information to support regulatory approval. While PROMs can prove insightful as an analytic tool for complex disorders, the potential barriers to PROM design, development, and interpretation are such that the Food and Drug Administration (FDA) developed a Guidance for Industry document (pdf) to aid in development of PROMs. Choice of PROMs for use in interventional trials must then be carefully informed.

Dr. Tara Symonds and her colleagues at Clinical Outcomes Solutions (COS) recently reported out a literature review of available PROMs that focus on type 1 myotonic dystrophy (DM1). COS a is health economics and outcomes research consulting group with considerable experience in understanding PROM design and implementation in clinical studies. Disclosure: The COS project was funded by Biogen, a company engaged in therapy development in DM1.

Dr. Symonds and her group evaluated a health status measure (MDHI), three activities of daily living scales (DM1-Activ, DM-Activc, and Life-H), two health related quality of life measures (INQoL & INQoL Serbian), and five sleep and fatigue measures (ESS, DSS, CFS, FSS, and FDSS) comparing their validity, reliability, and ability to detect change of each to guide choice of PROMs for use in DM1 studies.

MDHI was viewed as the only measure that attempted to capture all aspects of a DM1 patient's life that were impacted. Design of MDHI specifically for DM, internal consistency of the tool across domains assessed, test-retest reliability, and design in compliance with FDA’s Guidance for Industry were viewed as favorable traits. It was also noted that construct validity had been established for MDHI via comparison with a variety of existing functional measures (e.g., MMT, grip testing, and timed function tests).

DM1-Activ also was considered to have good validity and reliability and showed construct validity when compared to various manual testing measures and the Muscular Impairment Rating Scale (MIRS).

Most other PROMs assessed by the authors were viewed as more limited in capability and performance, and all PROMs were thought to require further assessment of responsiveness and meaningful change thresholds in interventional clinical trials. Dr. Symonds and team concluded that MDHI is arguably the best measure for use in clinical studies and trials provided that the critical areas of responsiveness and definition of meaningful change to patient are addressed. DM1-Activ also was deemed to have potential as a PROM in interventional trials, as long as content validity is explored further and the issues of responsiveness and meaningful change prove acceptable. Other measures were considered acceptable in evaluation of specific domains of the symptomatology of DM1.

FDA’s Guidance for Industry supports the use of well-designed and implemented PROMs as putative primary endpoint measures for clinical trials. Even as a secondary measure, a carefully selected PROM can bring considerable value to clinical trials, not the least is insight into meaningful benefit to the patient. The publication by Dr. Symonds and colleagues provides an evaluation of currently available tools by experts outside of the DM community. While current drug discovery and development efforts have focused on skeletal muscle function, desired treatments for DM will have to address a much wider disease burden. Validated and reliable PROMs with an ability to capture changes in multiple symptoms important to DM1 patients may prove to be a valuable tool in natural history studies and definitive clinical trials.

Reference:

A Review of Patient Reported Outcome Measures for Use in DM1 Patients
Symonds T, Randall JA, Campbell P.
Muscle Nerve. 2016 Nov 11. doi: 10.1002/mus.25469.

To date, technological hurdles have been a barrier to creating a mouse model for type 2 myotonic dystrophy (DM2), hindering understanding and treatment development for this disorder. But that’s about to change, thanks in part to the work of Łukasz Sznajder, Ph.D., a recipient of a 2016-2017 research fellowship grant from MDF.

"Currently, there are only cellular and fruit fly models available," says Dr. Sznajder, "and they’re not sufficient to understand the complex nature of DM2. A mouse model is urgently necessary to break this barrier."

Without mouse models it would have been impossible to develop the drugs now being tested to treat most neuromuscular disorders, including type 1 myotonic dystrophy (DM1).

A DM2 mouse model “will provide an excellent platform to evaluate DM2 phenotypes,” Dr. Sznajder says.

It would also allow researchers to study tissues that are hard to obtain from patients, such as those from the cardiac muscle and brain, and it would shed light on the differences between DM1 and DM2.

"My proposed model represents a unique opportunity to distinguish the differences between DM1 and DM2," Sznajder says. "We expect to answer puzzling questions, such as why there is no congenital-onset form of DM2," which is caused by several thousand CCTG repeats in the first intron of the CNBP gene.

"It is worth mentioning that the size of this mutation is several times that of the expansion that leads to DM1," Sznajder says. That, he notes, poses some challenges in developing a DM2 mouse model. "First, the amplification of even a few hundred repeats is not possible using conventional strategies. Second, the precise insertion of these repeats into the mouse CNBP gene is a highly inefficient process," he says.

"New technologies have remarkably improved the efficiency of genome engineering, and we hope to use these technologies to overcome the current challenges in DM2 modeling," he says.

Moving Toward DM2 Therapies

A mouse model will also allow Dr. Sznajder and his team to test therapeutic strategies for DM2 like antisense oligonucleotides and small molecules.

The antisense oligonucleotide-based drug IONIS-DMPKRx, designed to block harmful interactions between expanded RNA repeats and cellular proteins in DM1, is now in a phase 1-2 trial. Dr. Sznajder and his colleagues hope to develop a similar molecule to treat DM2.

"It is scientifically possible to adjust the oligonucleotide sequence to make it useful for DM2," Sznajder says. "However, a good mouse model of the disease is needed to test the efficiency of this or other approaches." His new DM2 mouse is expected to provide this vital tool.

A Passion for DM Research

Dr. Sznajder recently moved from his native Poland to realize his dream of working with a renowned DM researcher in the United States.

Coming of age in Poland in the 2000s, Sznajder decided to become a biomedical scientist, ultimately earning his doctorate in biotechnology and molecular biology from the Adam Mickiewicz University in Poznań in December 2015.

"For some time," he says, "I had dreamed about working at a prestigious university in the United States under the supervision of someone who would enable me to develop my scientific career while following my passion for research in myotonic dystrophy."

During his graduate studies, Sznajder was fortunate enough to work under Dr. Krzysztof Sobczak, who had been a postdoc in the laboratory of Dr. Charles Thornton, a DM researcher at the University of Rochester in New York state and a colleague of Dr. Maurice Swanson.

Under the mentorship of Dr. Sobczak, Sznajder started working on RNA toxicity and MBNL proteins, which he describes as "critical players in the molecular cascade of DM."

Dr. Sznajder is continuing his vital DM research under Dr. Maurice Swanson at the University of Florida.

As a consequence of the retention of mutant DMPK transcripts in the nucleus in DM1, patients express baseline levels of DMPK protein that are already half those of unaffected individuals. Since a key therapeutic strategy relies upon degradation of DMPK transcripts using antisense oligonucleotides (ASO), there are concerns as to whether essential functions of DMPK may be comprised and thereby contribute to the pathogenesis in DM1.

A University of Rochester team led by Dr. Charles Thornton has addressed this issue using mouse models with constitutive (genetic deletion) or acquired (ASO reduction) reductions in Dmpk. The function of DMPK is currently unknown. Prior reports in genetic models have shown that mice with heterozygous deletion of Dmpk exhibit cardiac conduction system defects, while those with homozygous deletion show skeletal muscle myopathy and weakness. Thus optimization of the ability of ASOs to target and degrade DMPK transcripts could exacerbate cardiac and skeletal muscle dysfunction in DM1.

Dr. Thornton and colleagues reevaluated the impact of genetic and ASO-induced reductions in Dmpk in two mouse models. They saw no effect of genetic deletion or ASO knockdown on cardiac (heart rate, PR interval, QRS duration, left ventricular contractile parameters) or skeletal (grip strength) functional measures, despite the substantial reductions that were achieved in Dmpk protein levels. Current strategies for ASO knockdown in DM1 utilize an allele-selective approach by targeting and degrading the mutant DMPK transcripts that are retained in the nucleus. However, there is the possibility that wild-type DMPK transcripts that traffic to the cytoplasm may also be degraded, as the next generation ASO chemistries result in more effective delivery to skeletal and cardiac muscles.

Yet despite the concern that substantial reductions in Dmpk protein may impact these muscles, Dr. Thornton’s team did not uncover any pathophysiology associated with Dmpk knockdown, even when genetic and ASO strategies were combined to yield as much as 90% reduction. Differences between the results of the Thornton team and prior investigations may relate to technical differences in the studies, mouse background strain differences, or features of the genetic knockout alleles.

The levels of Dmpk silencing seen in this study most likely would exceed those that could be obtained in DM1 patients, even with a highly effective ASO drug. The level of reduction of Dmpk in the mouse models also would likely exceed the reductions that are necessary to effectively restore the DM1-linked changes in mRNA splicing, and thereby mitigate DM1 signs and symptoms.

Hence these findings support the notion that strategies to increase the effectiveness of ASO candidate therapies can be effective in DM1 without increasing the risk of cardiac and skeletal muscle events.

Reference:

Dmpk gene deletion or antisense knockdown does not compromise cardiac or skeletal muscle function in mice.
Carrell ST, Carrell EM, Auerbach D, Pandey SK, Bennett CF, Dirksen RT, Thornton CA.
Hum Mol Genet. 2016 Aug 13. pii: ddw266.

Endpoint Award

Dr. Donovan Lott, of the University of Florida, has successfully competed for support of his project, “Development of Magnetic Resonance Imaging as an Endpoint in Myotonic Dystrophy Type 1.” The award is for one year, at $150,000. 

Dr. Lott’s group has extensive experience in developing skeletal muscle MRI as an endpoint measure in neuromuscular disease, including their ongoing interactions with FDA to obtain biomarker qualification. There have been very few imaging studies of myotonic dystrophy skeletal muscle. Given the considerable potential of MRI, an assessment of the feasibility of the approach in DM is essential.

Drug development in myotonic dystrophy (DM) enjoys an important advantage—having the tools in hand to show that a drug candidate gains access to and modifies the primary cause of the disease. Since expanded repeats in DMPK (in DM1) and CNBP (DM2) sequester MBNL1 protein and cause easily assessable molecular (mis-splicing of a large set of genes) and physiological (myotonia) changes, we can get an early signal in Phase 1/2 trials that a candidate therapy engages and modulates a key drug discovery and development target.

The existence of clear endpoints for early stage clinical trials helps de-risk DM for investments by pharmaceutical and biotechnology companies. By contrast, the development of endpoint measures that either establish, or are surrogates for, a clinically meaningful benefit is a clear need for Phase 3 trials in DM, in order to gain regulatory approval for a drug or biologic.

With the objective of meeting this critical need, MDF issued a Request for Applications to identify and support a project with the objective of developing new, clinically meaningful endpoint measures or refining endpoint measures already in development. Dr. Donovan’s project received the highest rating from the MDF peer review panel and was selected for funding.

Dr. Donovan’s team will complete a project in 25 DM1 patients. In these studies, they will quantitatively assess upper and lower limb muscle status by MRI and relate findings to a battery of functional measures, thereby taking the first steps toward development and qualification of MRI as a sensitive and non-invasive biomarker for clinical trials in DM. A qualified endpoint measure, with established linkage to clinically meaningful outcomes for patients, will make each of our clinical trials considerably more efficient and informative.

UK Natural History Grant 

Professor Hanns Lochmuller and Newcastle University are being awarded a $125,000 grant to extend a natural history study of 200-400 adult DM1 patients. 

The Newcastle group is currently funded by the UK National Institute for Health Research to recruit and collect natural history data on the DM1 cohort for one year, through March 31, 2017. MDF funding will leverage this existing funding to allow Professor Lochmuller and colleagues to reach the upper end of their recruitment target and to extend the duration of data collection from this valuable cohort for an additional year. Data collection involves a wide variety of endpoints, with the aggregate data assisting in the planning, design, and recruitment of future clinical trials, as well as supporting identification of putative biomarkers of DM1.

Robust natural history studies are critical to the development of endpoint measures that reflect clinically meaningful benefit for use in registration trials. MDF and MDF UK are pleased to be able to leverage other grant funding to increase the value and impact of this study.

Dr. Yao Yao, a former MDF Fellow, has brought us a step closer to effective muscle stem cell therapies for muscular dystrophy.

Dr. Yao identified a cell signaling mechanism by which muscle stem cells are directed to aid muscle regeneration. His work was recently published in the prestigious research journal, Nature Communications.

Muscle stem cells are responsible for the growth and regeneration of skeletal muscles. They are located immediately adjacent to muscle fibers and divide and fuse with the muscle fiber to increase its size and strength, for example, when you exercise.

These stem cells are also the means by which damaged and weakened muscles are strengthened and repaired. The process is very similar, whether the muscle damage is due to an injury or a muscle wasting disease, like DM.

Because of their vital role in muscle regeneration, muscle stem cells are a potentially important target for developing therapies. Increasing their activity should improve muscle repair.

The development of cell therapies has been difficult, however, because we don’t sufficiently understand stem cell biology. Muscle stem cells participate in both muscle regeneration and the fatty deterioration of muscle. Understanding the regulation of muscle stem cell fate is a critical, early step in therapy development.

A better understanding of the properties of muscle stem cells (and the molecular and cellular mechanisms that control their fate) will be essential to using them in therapies. MDF is pleased to have supported Dr. Yao’s advances in the therapeutic potential for muscle stem cells.

Dr. Yao currently holds a faculty position in the College of Pharmacy at the University of Minnesota, Duluth. For more details on Dr. Yao’s lab, click here.

Reference:

Laminin regulates PDGFRβ(+) cell stemness and muscle development.
Yao Y, Norris EH, E Mason C, Strickland S. 
Nat Commun. 2016 May 3.

There has been relatively little research on quality of life for DM2 patients, and DM2 is often considered “less severe” than DM1. However, a new study identified a subset of DM2 patients who are impacted as severely as those with DM1.

Dr. Dusanka Savic-Pavicevic and colleagues recently published a comparison of genetically confirmed DM2 and DM1 patients using a variety of quality of life measures.

The research team found no differences between DM2 and DM1 in the overall and physical composite scores of the survey.

Emotional and mental composite scores were typically better in DM2 patients, as were independence and body image scores. Disease impact on cognition, strength, heart function, breathing and cataracts were also less severe in DM2.

The DM2 patients who reported worse scores were typically older, weaker, and had higher fatigue levels than the DM2 patients who scored better on certain segments of the surveys. Lower quality of life scores were also associated with lower cognitive achievement, memory impairment and lower educational levels.

A deeper understanding of the correlation of age, strength, and fatigue with quality of life in DM2 is needed to facilitate better patient outcomes. More DM2 studies like this will pave the way for higher quality care.

Reference:

Quality of life in patients with myotonic dystrophy type 2.
Rakocevic Stojanovic V, Peric S, Paunic T, Pesovic J, Vujnic M, Peric M, Nikolic A, Lavrnic D, Savic Pavicevic D.
J Neurol Sci. 2016 Jun 15. 

“CRISPR-Cas9" (pronounced "crisper") is an acronym for the full name of a new cutting edge, gene-editing technology: “Clustered Regularly Interspaced Short Palindromic Repeat - Cas9". 

CRISPR-Cas9 has garnered wide research interest for its capacity to target and correct disease-causing mutations. A naturally occurring gene editing technology, it was first identified in bacteria, which use it to protect against invasive viruses. 

CRISPR and DM 

DM is a disease of RNA processing, and understanding RNA binding proteins is at the core of understanding DM. It is the reduced availability of the RNA binding proteins muscleblind and CUGBP1 that cause the alterations in RNA splicing leading to many, if not all, of the signs and symptoms of DM.  

New Breakthroughs in Targeting RNA from University of California

Dr. Gene Yeo’s lab at University of California, San Diego focuses on how gene expression is controlled at the level of RNA, the intermediary step in the DNA to RNA to protein pathway by which genes produce proteins. 

His lab is specifically interested in RNA processing, RNA binding proteins, and how defects in RNA binding proteins cause neurological and neuromuscular diseases like DM.

In a recent publication in Cell and a more detailed commentary on technology development in Bioessays, Yeo and colleagues show that incorporating a fluorescent tag into the CRISPR-Cas9 system allows them to target and track the movements of RNA within individual living cells.  

Importantly, the binding of the CRISPR-Cas9 tracker did not appear to influence the level of RNA or its function, letting it function as an inert tracking tool. We know that proper RNA localization and movement within the cell is essential to faithfully transmit the genetic code into protein synthesis.  

This latest publication offers an opportunity to better understand the disease mechanisms in DM (through precise tracking of intracellular movement of RNA), an essential step in therapy development. 

CRISPR for DM Mouse Models 

Another important use of CRISPR-Cas9 technology is in the development of better DM mouse models to support studies of disease mechanisms and developing therapies. 

This novel gene editing approach allows triplet repeat expansions to be precisely inserted into the mouse DMPK and ZNF9 genes in the same locations the expansions occur in the human genes. MDF is currently working with researchers to improve DM models, including mouse models, and make them available to our research community through this strategy.

The Future of CRISPR

Although there are considerable hurdles to overcome, we will likely see CRISPR-Cas9 technology in clinical trials in the next several years as a novel, potentially disease-mitigating approach.  

Since editing of the genome is involved, unintended consequences could be severe, so the first uses of CRISPR-Cas9 in humans will draw considerable attention from national regulatory authorities like the Food and Drug Administration (FDA) in the US, and the European Medicines Agency (EMA) in Europe.

We look forward to gene editing progress on the use of CRISPR-Cas9 to treat disease, and learning more about the potential for this approach to edit the CTG and CTTG expansions in DM1 and DM2. 

References:

For more information on CRISPR, see a recent New Yorker article, The Gene Hackers.

Programmable RNA Tracking in Live Cells with CRISPR/Cas9.
Nelles DA, Fang MY, O'Connell MR, Xu JL, Markmiller SJ, Doudna JA, Yeo GW.
Cell. 2016 Apr 7. Epub 2016 Mar 17.

Applications of Cas9 as an RNA-programmed RNA-binding protein.
Nelles DA, Fang MY, Aigner S, Yeo GW.
Bioessays. 2015 Jul. Epub 2015 Apr 16.

Dr. Matt Disney brings an unusual and increasingly valuable skill to therapy development for DM—he’s a chemist. 

Dr. Disney’s background, position and interests give him the flexibility to do exploratory work that leverages the latest advances in RNA biology in order to target the unique disease mechanisms of DM. By focusing on small molecules, his work has the potential to target all organ systems affected by DM and move toward practical applications in treating DM.

Medicinal chemists working on rare diseases at universities or non-profit research organizations, like his home base at The Scripps Research Institute, Florida, are rare, as they usually are based in the Pharma/Biotech sector.  

The NIH has recently awarded two research grants in support of Dr. Disney’s research.  

The first grant is an NIH Director’s Pioneer Award— a program that the NIH describes as supporting “individual scientists of exceptional creativity, who propose pioneering and transforming approaches to major challenges in biomedical and behavioral research.” 

The Pioneer program is extremely competitive, with only 13 Pioneer Awards issued by NIH in 2015. This five-year, $960,000/year award seeks to utilize the defective gene as a catalyst for the synthesis of highly selective therapeutic compounds directly in the affected cells. The approach ensures that the drug will be available in precisely the cells where it is needed, thereby entirely avoiding issues encountered by traditional drug development and delivery strategies.

The second grant award is a renewal of Dr. Disney’s current NIH funding, providing an additional 5 years and $2.5M of support. In this work, he is trying to overcome the limitations of oligonucleotide therapeutics traditionally used to target RNA through the design, synthesis, and evaluation of small drug-like compounds with potent RNA binding capacity. Dr. Disney and colleagues have recently described this novel platform in an article in Bioorganic & Medicinal Chemistry Letters.

Reference:

Comparison of small molecules and oligonucleotides that target a toxic, non-coding RNA.
Costales MG, Rzuczek SG, and Disney MD.
Bioorg Med Chem Lett. 2016 Jun 1. Epub 2016 Apr 11.

While it has been widely recognized by clinicians treating DM that gender plays an important role in determining disease heterogeneity and progression, there is little hard data to support differential response of males and females to DM.

Dr. Guillaume Bassez and a large team in France and Canada have recently published an analysis of gender as a modifying factor of the DM1 phenotype. In the study, they evaluated 1,409 adult DM1 patients in the French DM-Scope registry. Importantly, findings were validated using additional cohorts from the AFM-Telethon DM1 survey and the French National Health Service Database.

The research team identified clear differences in symptoms detected by gender. Adult males were much more likely to present with “traditional” DM1 signs and symptoms, including muscle weakness and myotonia, cognitive impairment, and cardiac and respiratory involvement. By contrast, adult females had symptoms that were less suggestive of “traditional” DM1, instead showing predominance of cataracts, obesity, thyroid signs, and GI symptoms.  

The differing constellation of symptoms in the two sexes led the research team to conclude that women were often less symptomatic of DM1 and thus often undiagnosed, although this was potentially offset by the finding that women appeared to more often seek specialist care for DM1 symptoms.

Gender matters in DM1. The biologic mechanisms underlying the gender differences that the French group has documented for DM1 are unknown. To improve diagnosis and management of DM1, as well as to better plan for inclusion of both genders in clinical trials, it will be important to understand the factors responsible for the very different onset and progression of DM1 in males and females.

The heterogeneity (variability) that characterizes the clinical manifestations of myotonic dystrophy type 1 (DM1) has been well recognized by physicians, patients, and family members. Although the length of CTG expansions in the DMPK gene correlates with age of onset and severity of DM1, knowledge of other factors that impact progression of DM1 currently is rather limited.  

Intensive analysis of large cohorts of DM1 and DM2 patients are underway to identify both genetic modifiers, gene variants that can speed or slow disease onset or progression, and biomarkers, measurable indicators in blood or other tissues that can be critical for studies of disease progression and clinical trials. 

MDF is partnering with the research community to identify biomarkers and move them toward qualification by the regulatory authorities as drug development tools.

Understanding of the biological factors behind heterogeneity of DM1 is critical to help patients better understand their disease, as well as to help drug developers design successful clinical trials. The studies necessary to identify the underlying factors require large cohorts of affected individuals—for this reason, it is essential that patients become involved in research efforts that build the requisite databases, such as the Myotonic Dystrophy Family Registry.