When did you first come into contact with Angelman syndrome?

At Ovid, we believe that neuroscience is the next frontier for exciting research and developments for medical therapies. However, there is still a lack of understanding of the complexity of the brain and nervous system, as evidenced by the many failed trials for the more prevalent conditions, and a lack of research in the more challenging orphan neurological diseases. However, we saw that the research was evolving very rapidly. Early in the history of Ovid we began to understand that neurodevelopmental conditions such as Angelman syndrome had no therapies directly addressing them. Since the company launched in 2014, our first focus was working to understand how our lead therapeutic candidate, OV101 (gaboxadol), may play a role in treating Angelman Syndrome.

What makes Angelman syndrome interesting for you from a scientific point of view?

From a scientific point of view, deficits in GABA levels or functioning have been associated with the symptoms of Angelman syndrome due to what we believe is a fundamental mechanism of the condition which is an imbalance in tonic inhibition. Tonic inhibition is the ability to differentiate ‘signal’ in the brain from background ‘noise’, and is mediated by two key chemical messengers (neurotransmiPers) in the brain called glutamate (which is ‘excitatory’) and GABA (which is ‘inhibitory’). The lack of GABA in Angelman syndrome leads to lack of the inhibitory signal and thus to many of the symptoms we see in Angelman syndrome. OV101 is an oral drug in late clinical development for Angelman syndrome, and could potentially be the first therapeutic option to make a meaningful change for individuals with Angelman syndrome and their families by addressing the severe symptoms of the condition.

How do you assess the future of drug treatment for Angelman syndrome?

Current treatment approaches in Angelman syndrome focus on managing specific symptoms. There is a high unmet medical need for therapies that target the root cause of the disease and improve these symptoms. At Ovid Therapeutics, our mission is to make a difference. A difference for rare neurological disease communities that truly need it and a difference in a field where change does not come easily: neuroscience drug development.

If OV101 - Gaboxadol is approved, what can we expect? How can Angelman patients benefit from OV 101?

Tonic inhibition is an important mechanism in the nervous system because it modulates the ability of cells in the brain to distinguish a real signal from noise, and deficits in GABA levels or functioning has been associated with the symptoms of Angelman syndrome. Studies of OV101 in animal models of Angelman syndrome show OV101 may restore tonic inhibition, improve gait and balance, improve memory, and have positive behavior effects. Our first clinical study in Angelman syndrome with OV101, called STARS, showed signals of improvement in several symptoms of Angelman syndrome including sleep, motor Dr. Amit Rakhit is president and Chief Medical Officer of Ovid Therapeutics. He is responsible for the drug development and commercialization of new drugs in the Ovid porWolio. Dr. Rakhit worked in India together with Mother Teresa at the Missionaries of Charity (CalcuPa). He is commiPed to human rights and has been working in the health sector for over 20 years. Virtual on tour ASA ANGELMAN SYNDROME ALLIANCE New York „For the future of Angelman patients, I hope to make a meaningful change for individuals with Angelman syndrome and their families and bring about positive impact in their daily lives.“ Dr. Amit Rakhit Ovid Therapeutics Page 2 function, and behavior. Research of OV101 in individuals with Angelman syndrome is now in the Phase 3 stage as the NEPTUNE study in children ages 4-12 years old and we expect to have results from this trial in the 4th quarter of 2020.

How does the drug OV-101 work? Which ASpatients will benefit most of that treatment, concerning age and genotype?

Our lead therapeutic candidate, OV101 (gaboxadol), is a first-in-class, oral, highly selective extra-synaptic GABAA receptor (GABAAR) agonist. It passes the blood-brain barrier and binds tightly to the unique extrasynaptic GABAA receptors on neurons throughout the brain, restoring the levels of tonic inhibition that exist when intrinsic GABAA levels are low. OV101 is different than other GABAlike compounds because it is a pure agonist. That is, it can interact with the GABA receptor directly just like GABA normally does. Other compounds are typically allosteric modulators, that is they need intrinsic GABA to be around to have their effect. Also, OV101 primarily acts in the extrasynaptic space, which is the area around brain cells (neurons) that is thought to be heavily involved in tonic inhibition. We believe that all ages of individuals with Angelman syndrome will benefit from therapies given our results from the STARS trial which occurred in adults and adolescents and our hopes for the NEPTUNE trial results in children. However we will need to await these trial results to have a bePer understanding. It is encouraging to see that emerging data in individuals with Angelman syndrome seem to indicate that all ages have the potential to respond to clinical and medical therapy. As to genotypes, we are continually learning, and we will need to do more research to understand specifically if there are certain genotypes that respond differently than others.

More to come. Please tell us something about OV titi1. What is that? What can we expect of this treatment?

Ovid Therapeutics is advancing the search for therapeutic options for Angelman syndrome in addition to OV101. With OVtiti1 we are currently exploring microRNA and its involvement in regulating UBE3A antisense that blocks UBE3A expression. The most common cause of Angelman syndrome is the result of the loss of functional UBE3A protein due to defect of UBE3A gene. Our aim is to develop a disease-modifying noncoding microRNA vector that reduces expression of UBE3A-antisense and restores UBE3A expression. We are in early stages of our research and hope to announce more soon.

How do you rate the development opportunities of "full-grown Angelman brains"?

As mentioned previously, there seems to be emerging research that suggests that all ages of individuals can benefit from clinical and medical therapies, so that young as well as older individuals may see positive changes. We were encouraged by the signals we saw in the data from our STARS trial in adolescents and adults (ages 13-49 years) so we are hopeful that the signals we saw there will be confirmed in our phase 3 trial NEPTUNE.

How important is Ovid Therapeutics in terms of future treatment of AS?

OV101 is currently our lead program in clinical development for Angelman syndrome and could potentially be the first therapeutic option to make a meaningful impact in the lives of individuals with Angelman syndrome and their families. We hope to make a meaningful contribution to the science, understanding, and future treatment options for this condition.

Is there anything you want to say to the ASfamilies?

Dedication to us means not only relentless pursuit of meaningful scientific discovery, but also building strong connections with individuals and families with rare neurologic conditions. Being embedded into these communities, I am continually moved by your stories and inspired by your courage. Your input helps guide our research and trials, and continues to influence our overall development strategy. I am honored to work alongside you with the singular goal to provide meaningful impact for those living with Angelman syndrome.

In conversation with Bernhard Horsthemke

Prof. Dr. B. Horsthemke was the Director of the Institute of Human Genetics at the University Hospital Essen from 2001 to 2019. He has been familiar with research on Angelman syndrome for more than 30 years and is one of the leading Angelman experts in Germany. In his research he devotes himself, among other things, to genomic imprinting, which was groundbreaking for the understanding of AS. His outstanding scientific achievements are internationally appreciated.

In 2007 he was awarded the Dr. Claudia Benton Award of the Angelman Syndrome Foundation (USA). In 2016 he received the Medal of Honour of the German Society for Human Genetics (GfH). The genetic studies of Prof. Dr. Horsthemke have contributed to the basis for the ASO therapy.

When did you first come into contact with Angelman syndrome?

I started a research project on the genetics of PraderWilli syndrome (PWS) in 1986. When it became known in 1989 that the genetic locus for Angelman Syndrome (AS) on chromosome 15 is also in the region q11q13, I extended the research project to Angelman syndrome. I was also present at the founding meeting of the Angelman Parent Association Germany in 1993.

What makes Angelman syndrome interesting for you from a scientific point of view?

Prader-Willi syndrome and Angelman syndrome involve genes that are subject to genomic imprinting. Of the 20,000 human genes, only 100 are imprinted. The PWS genes are only active on the paternal chromosome 15, the AS gene in the brain only on the maternal chromosome 15. I was fascinated by this type of gene regulation, in which DNA methylation plays a role. My team has not only revolutionized the genetic diagnosis of PWS and AS with the methylation test, but has also identified the long RNA (SNHG14) that silences the UBE3A gene on the paternal chromosome 15 and which is now the target of ASO therapy. With the ASO, this long RNA is stopped, so that the paternal copy of the UBE3A gene can become active and replace the missing or defective maternal copy. ASA ANGELMAN SYNDROME ALLIANCE Virtual on tour Essen

"I am committed to Angelman Syndrome research because it gives us new insights into the regulation of imprinted genes, which can also be important for the development of future therapies“

How do you assess the future of Angelman syndrome?

Unfortunately, a causal therapy is not that simple, and I do not believe that there will be a complete cure in the foreseeable future. However, I am confident that some symptoms can be alleviated in the future, but only if you start the therapy very early. This therapy will probably have to be done for life.

What do you expect from the clinical trials of ASO therapy? How can Angelman patients benefit from ASO therapy?

The ASO studies planned for 2020 will focus on the tolerability and possible side effects of ASOs, on finding the right dose and on verifying that the chosen clinical endpoints are appropriate. These studies will involve very few patients. Only when the ASOs have been proven to be safe will further studies involving slightly more patients be carried out in order to see if and which symptoms improve under therapy.

"My mission is to connect basic
research and clinical application.“

What experiences do you and your team have with ASO therapies for other diseases?

In spinal muscular atrophy (SMA), ASOs are a success story. Here, the treatment clearly leads to an improvement in the clinical picture. The success was so convincing in the first study that it was discontinued in order to be able to treat more patients.

What role do you think Germany plays in the development and research of AS drugs?

Unfortunately, Germany does not play a direct role here. However, Germany is a good location for clinical trials. In addition, our health insurance companies – more so than the health systems in other countries - are prepared to cover very expensive therapies.

How do you assess the developmental possibilities of "grown-up Angelman brains"?

That is hard to say. Although older brains still have some plasticity, I am skeptical about this. Experiments in mice show that the best effects can be achieved by switching on the UBE3A gene as early as possible, preferably before birth.

Are there (comparative) studies that show that an unused brain area has been reactivated after causal therapy?

So far there is no causal therapy for other genetic brain diseases. It is known that other brain regions can step in a`er injuries (accident, stroke). However, these are regionally limited injuries; this situation cannot be compared to Angelman syndrome. In Angelman syndrome, all brain cells of a certain type are affected; no other cells can step in, but the affected cells have to be "repaired".

They expand the AS parent association competence as a medical advisory board. Without hesitation, you have promised, why?

In rare diseases, there is a mutual give and take between parents and patients on the one hand and researchers on the other. Parents and patients benefit from our exper.se and we benefit from their experience and samples for our investigations. Since our research is funded by society, I think it is morally imperative that we researchers also give something back to society. One possibility is to participate in parent support groups.

Conflicts:

Prof. Dr. B. Horsthemke is a consultant for Ionis Pharmaceuticals, has received grants for conferences from Ionis Pharmaceuticals and Pfizer, and has filed two patents with ROCHE.

In conversation with Brenda Vincenzi, MD Together with its American "subsidiary" Genentech and other partners, Roche is the largest biotech company in the world. Since 2015, the pharmaceutical giant has been dedicated to Angelman syndrome with its own program. According to FREESIAS, an observational study on Angelman syndrome, the company will start the ASO therapy study TANGELO (Targeting Angelman Syndrome with an oligo-nucleotide) in the summer. Reason enough for us to ask Brenda Vincenzi, MD (Ass. Medical Director, Roche):

When did you first come into contact with Angelman syndrome?

I trained in neuropsychiatry and worked with children 0-17 yo with diverse neurodevelopmental and neuropsychiatric disorders. In 2014, during my first year of residency, I was asked to evaluate a 12- month-old girl because of developmental delay. Although the pediatrician initially tried to reassure the family, the mother knew that something was not right. It did take a few weeks to confirm the diagnosis, Angelman syndrome. It is impossible to forget the tears of the little girl’s mother while I communicated the diagnosis and answered that no, there was no treatment available for their little girl.

What makes Angelman syndrome interesting for you from a scientific point of view?

I would like to cite dr. Art Beaudet, a professor at Houston’s Baylor College of Medicine: “Compared to 30 other paediatric neurological disorders, I would make the case that Angelman syndrome holds one of the single most optimistic possibilities for a treatment”. The biology of AS almost calls out for intervention and at Roche we are very excited to be able to act on it. Although there are current knowledge gaps around our understanding of the disease, Angelman syndrome can function as a model that allows researchers to investigate the complexity of neurodevelopment and brain maturation.

How do you assess the future of drug treatment for Angelman syndrome?

I want to look at the future with optimistic eyes. This is a very exciting time for the Angelman community as many have decided to invest in better understanding AS. It is important that we continue to work together with patients’ organizations, families, clinician and researchers, health authorities and pharma companies to build the bridge of knowledge around AS and achieve something meaningful for patients and their families.

"I stand up for AS research because we need to bring more attention to neurogenetic disorders like Angelman Syndrome and to advance this field of research in order to offer patients and their families meaningful treatment options.“

What do you expect from the clinical studies concerning ASO therapy? How can Angelman patients benefit from ASO therapy?

Roche listens and learns from the AS community and works to identify what is truly important for patients and their families. Our goal is to bring to the market a therapy that will address all the symptoms of the underlying disease. We are optimistic that our ASO therapy will be truly disease modifying, which would not only improve the health and wellbeing of affected children but also improve the quality of life for entire families. Moreover, our target at Roche is to include in our future clinical trials all ages and all genotypes.

What do you expect of the gene therapy, concerning AS treatment? How do you assess the chances and risks of this treatment?

Gene therapy is an exciting field that on one hand has a track record of troubling setbacks but on the other has incredible potential for curing a plethora of genetic disorders in different disease areas. Given that AS is a monogenic disorder, the likelihood of reaching a successful form of gene therapy is, in my opinion, high.

What are the risks associated with ASO therapy for Angelman syndrome?

Our Roche ASO treatment went through a very strict selection process. More than 2,300 molecules were screened and the most potent and safest LNA was selected for our clinical development program. In animals’ experiments our drug was safe and well tolerated so that we do not expect any significant side effect from the drug.

How do you rate the development opportunities of "full-grown Angelman brains“?

At Roche, we always look at the big picture, which means including in our clinical development plans all ages whenever possible. Although animal studies have shown that the impact of a treatment could have different effects when provided to younger or older animals, we currently do not know how this works in humans. This makes this study very important, as the learnings will be used to provide hopeful treatment opportunities to patients of all ages and with all genotypes.

Are there any (comparative) studies that prove that an unused brain area has been reactivated after causal therapy?

As mentioned, we do not have any human data on the efficacy of our treatment in AS individuals. Nevertheless it was recently that reinstatement of Ube3a in adult mice rescues the excitatory and inhibitory synaptic deficits in the pre-frontal cortex, supporting the idea that UBE3A restoration leads to a change in cortical circuit activity demonstrated (Rotaru et al. Adult Ube3a Gene Reinstatement Restores the Electrophysiological Deficits of Prefrontal Cortex Layer 5 Neurons in a Mouse Model of Angelman Syndrome. The Journal of Neuroscience: the official journal of the Society for Neuroscience 2018;38:8011-30).

Is there anything you want to say to the AS-families?

I am a clinician by training but also a mother of two. I want you all to know that the AS Roche team is working non-stop with one goal in mind: to bring you and your children a meaningful treatment that will improve the quality of life of your child and of the whole family.

Neuren Pharmaceuticals is a biopharmaceucal company focused on developing new therapies for neurodevelopmental disorders. In 2019, the company is causing a stir with its headline: NNZ-2591 has shown positive effects in a mouse model of Angelman syndrome, treating all symptoms of the disease. Meanwhile the drug is in a Phase 1 clinical trial and has Orphan Drug status in the US. High time to explore a little bit there.

Nancy E. Jones, PhD is the Vice President of Clinical Development for Neuren.
She works with her team and clinician experts to design and execute the clinical trials for the development programs. Nancy is passionate about facilita

“Individuals with Angelman and their families deserve high quality, evidence-based information, and the most innovative treatments possible.“

Regarding Neuren’s research in neurodevelopmental disorders, when and why did Neuren start to get involved in Angelman-Syndrome's research?
Neurodevelopmental disorders arise from a range of genetic and neuropathological causes and are characteristically very heterogeneous in their presentation across patients. But many have a similar neurobiological dysfunction in common: problems with the connectivity between brain cells (neurons and their supporting cells). The problem with these connections, or synapses, means that from a treatment perspective, a very diverse range of disorders may actually have a common treatable dysfunction. Neuren’s development portfolio includes compounds that have been shown to improve synaptic connectivity in preclinical models. One of these novel treatments, trofinetide, has already shown evidence in clinical trials conducted by Neuren that it can improve clinical symptoms in other rare, genetically based disorders. Given the underlying problems with synaptic connectivity in Angelman, we felt that our compound, NNZ-2591, could be a potentially useful treatment for Angelman syndrome. Our development program commenced in 2019 with very promising results in an Angelman mouse model after which we received Orphan Drug designation from the FDA.

In Neuren's pipeline, we see your candidate ‘NNZ-2591 in Angelman Syndrome’ already entered Phase 1. How is it going? What are the next steps?
Neuren is conducting a Phase 1 study in healthy, typically developing adults. This study will assess the safety and tolerability of treatment with NNZ-2591 and provide information on how the drug is absorbed and distributed throughout the body (the pharmacokinetics of the drug). The study is currently on-going. AYer the completion of the Phase 1, we will initiate the necessary steps to start an Angelman syndrome study in 2021. This is planned to be a Phase 2 study that will assess safety and efficacy of treatment with NNZ-2591. NNZ-2591 – what is this? How does it work? NNZ-2591 is a synthetic version of a fragment of Insulin-like growth factor (or IGF-1), a growth factor essential for brain development. The fragment, called “cGP”, regulates IGF-1 and inhibits inflammation in the brain. Normal brain function requires mature, well-maintained synapses. The UBE3A deficiency that occurs in Angelman syndrome impairs neuronal communication by reducing the brain’s ability to synthesize proteins needed to build synapses and by impacting microglia, specialized cells that maintain dendrites, the parts of neurons that form synapses.

  “By normalizing IGF-1 levels, NNZ-2591 restores the brain’s ability to create new synapses. By inhibiting inflammation, NNZ-2591 rescues the function of microglia in maintaining synapses.“

In which way can Angelman patients benefit from this treatment?
As was noted above, we believe that NNZ-2591 can have an effect on the underlying dysfunction in the synapses and the cells that regulate the growth and function of synapses. Therefore, the aim of treatment with NNZ-2591 is not only to have a fast-acting impact on a particular set of symptoms, but also to have an impact on brain architecture and function, which over time will lead to improvements across a wide range of symptoms of Angelman syndrome. In the Phase 2 study, we will be able to determine the effects on symptom severity in patients and identify which symptoms may be responsive to treatment.

“In the preclinical study in the Angelman mouse model, consistent improvements were seen in analogous symptoms relevant to and clinically important in patients including cognition, adaptive behaviors, motor function and seizures.“

What makes Angelman syndrome interesting from a scientific point of view?
As in most neurodevelopmental disabilities, Angelman is characterized by deficits in synaptic formation, maintenance and function. If NNZ-2591 results in clinical benefits for patients with Angelman syndrome, it will reinforce our belief that it could be useful in a wide range of syndromes for which there are currently no treatments.

How do you assess the future of drug treatment for Angelman syndrome?
The Angelman community is well-positioned to advance the clinical trials needed to develop potential treatments. The scientific advances that have been made in understanding the gene, and methodologies for gene therapy, but also our understanding of the pathology of Angelman syndrome has laid the foundation for advancing studies in both gene-modifying and medicinal treatments. Another important and critical contribution has been the collective efforts of the Angelman advocacy groups and caregiver communities to build the infrastructure to support clinical trials. Resources such as registries, outcome measures consortiums, clinical trial and scientific advisory committees and family-centered trial information have played a critical role in facilitating the development of clinical treatment programs for Angelman syndrome.

“We believe that it is possible to restore synaptic plasticity in adult patients.“

How do you rate the development opportunities of ‘full-grown Angelman brains’ in consideration of NNZ-2591?
The ability to grow new dendrites and to create functioning synapses is life-long although it may be somewhat diminished in later life. Whether the magnitude of clinical benefit is similar and whether longer duration of treatment is required will be assessed in later clinical trials. In a clinical trial of trofinetide, Neuren’s other drug candidate, in ReP syndrome patients up to age 45, the clinical benefit in older and younger subjects was comparable.

Did you choose to publish the research results of the mouse study regarding NNZ-2591 in Angelman Syndrome? If yes, where did you publish them?
The manuscript describing results from the mouse study in Angelman Syndrome (as well as Phelan McDermid and Pitt Hopkins syndromes) is presently in development.

Do you plan to roll out the study also into other countries, except Australia?
The locations for the planned study have not been finalized. When study locations are confirmed, these will be announced and posted on www.clinicaltrials.gov.

Is there anything you want to say to the European AS-families? How can they keep informed regarding future clinical trials of NNZ-2591?
Our aim is to be able to develop a meaningful treatment that would be available to all families. As we progress with our program, we will provide updates or announcements on our webpage: www.neurenpharma.com.

In conversation with Stormy Chamberlain, PhD On our virtual tour through the Angelman community, we stopped at the University of Connecticut to meet Stormy Chamberlain, PhD. In 2009 she established her own lap at Uconn, focused on human imprinting disorders, such as Angelman syndrome. With good reasons she is member of ASF Scientific Advisory Committee, because time and again she surprises the community with groundbreaking insights. Especially her research dealing with pluripotent stem cells usher in a new era of Angelman drug development. High time for us to inquire more precisely … 

When did you first come into contact with Angelman syndrome? What makes AS so special from a scientific point of view?

I first became aware of Angelman syndrome as a PhD student at the University of Florida in 1997. My thesis project involved finding the genes important for Prader- Willi syndrome using a mouse model, and I had to learn about and understand the reciprocal regulation of paternal and maternal copies of chromosome 15q. 

What makes Angelman syndrome interesting for you from a scientific point of view?

I have always been intrigued as to why evolution chose to turn off one of the copies of a gene that is so important for normal development. All placental mammals imprint UBE3A and it’s not clear why. One might argue that the dose of the gene is super important, but actually, expression from the maternal copy of UBE3A is increased over the course of neurodevelopment, just as the paternal copy is getting silenced, so the dosage argument doesn’t make a lot of sense. Although every placental mammal imprints UBE3A, there are subtle differences in how it achieved as well. This means that the imprinting is important, but evolution has come up with some slightly different ways to achieve it. I just think that the complexity of how this all happens is so interesting, and can reveal lessons that can be applied to other genes in the genome. 

„I am committed to AS research because I firmly believe that by investing in knowledge about a disorder and gene that science can make a therapeutic that is more likely to provide substantial benefit. AS will be an excellent example for other disorders.“  

One part of your research is focused on pluripotent stem cells. What exactly is it?

My lab uses human pluripotent stem cells as a model system. Some people use mice to study Angelman syndrome, but my lab uses human pluripotent stem cells. These cells can be converted into neurons, so we can study actual human neurons with the disorder. Furthermore, we can follow the process of imprinting during neurodevelopment. The stem cells express UBE3A from both parental copies, but as they are converted into neurons, the paternal copy of UBE3A becomes silenced. We study this process. The other cool feature about these cells is that if we use induced pluripotent stem cells (as opposed to human embryonic stem cells)—where we convert a patient blood cell or a skin cell into a pluripotent stem cell--they carry the genetics of the patient. 

Which role does pluripotent stem cells play for research on Angelman syndrome?

We can use pluripotent stem cells to study the process of imprinting during human neurodevelopment. This helps us understand how the different parts of the human genome regulate this process. We can also use the neurons created from the pluripotent stem cells to understand the deficits in early human neurons with Angelman syndrome. This is important to figure out what goes wrong first, so we can determine how loss of UBE3A causes it. It’s important to do this in human cells, since this also might differ between human and mouse. Finally, we have been using our pluripotent stem cell models to screen therapeutics that can activate paternal UBE3A. We have tested small molecules (such as topotecan), antisense oligonucleotides (ASOs), and shRNAs. The therapeutics that are DNA-based drugs, like ASOs and shRNAs, need to be tested in a human cell model because the DNA is different between humans and mice. These pluripotent stem cells are pretty much required for testing these therapeutics. 

How are pluripotent stem cells produced?

Many of our pluripotent stem cells are produced using reprogramming. We take a blood sample or skin sample from a patient and artificially express stem cell genes (OCT4, KLF4, SOX2, and MYC) using a viral vector. These genes jumpstart the stem cell program in the blood or skin cells, turning them into stem cells. We can also make Angelman syndrome-like deletions—either the large deletions seen in patients or smaller, specific mutations of UBE3A—using CRISPR/Cas9 to cut the DNA in human embryonic stem cells. This means that we can create identical twin stem cells with and without Angelman syndrome. 

How do you assess the possibility of using pluripotent stem cells as a possible therapeutic approach for the treatment of Angelman syndrome?

There is no possibility of using the stem cells as a therapeutic approach for AS. The brains of individuals with AS develop with normal structure and cell types overall. If we introduce new stem cells or neural stem cells, they are not likely to make the connections that they’re supposed to in order to be of benefit to the patient. Furthermore, the dangers of putting new cells into a brain is much greater than the anticipated benefit. There are much better and safer therapeutic approaches for AS. 

„My mission is to use my talents and tools to learn all we can about AS and contribute to a variety of therapeutic approaches. Along the way, my mission is to train the next generation of researchers who will do the same for AS and other disorders. “

Neuron models can be made of pluripotent stem cells. How can these neuron models help to understand Angelman syndrome? Could neuron models be developed for all AS genotypes? What added value could this bring to the AS research?

The neurons made from pluripotent stem cells can help us understand human gene regulation—how UBE3A and UBE3A-ATS are regulated during neural development. They can help us understand what are the earliest deficits in the neuron. If we can figure out how UBE3A causes the first deficits, those are the most critical to fix because other things are likely downstream of the primary deficits. They can also be used to test therapeutics. These pluripotent stem cell models can be made for all AS genotypes. We have already made them for deletions, multiple UBE3A mutations, and uniparental disomy. The only one we don’t have is imprinting defect. It’s valuable to have the different genotypes for a variety of reasons. First, the deletion type has really helped us look at regulation because there is only the paternal copy present. This has helped us understand how UBE3A-ATS silences UBE3A. The UBE3A mutation type really helps us narrow down which neuron deficits are caused by UBE3A (as opposed to loss of one copy of the other genes). One of our cell lines with a UBE3A mutation has revealed a new way to regulate UBE3A protein as well. The uniparental disomy type helps us understand whether those individuals make a little bit of UBE3A, which might give them different therapeutic options. We have also used uniparental disomy neurons to see whether therapeutic approaches turn on both paternal copies of UBE3A, which can make too much UBE3A a possibility. The cells have indicated that they may want to use a lower dose of ASO on individuals with uniparental disomy and imprinting defect (which also has 2 copies of UBE3A that act like they’re paternal).

What role could neuron models play in the success of clinical trials? (e.B. ASOs, AVV gene therapy, Neuren, OV101)

Our models aren’t as helpful for OV101 and Neuren approaches because it’s hard to extrapolate from a neuron in a dish to an organism. This might change as we get better at making organoids or mini-brains, which may have features more like actual brains. However for ASOs they can help and have already helped us identify the sequence to target and learn the “rules” for the drug. For instance, how much UBE3A can the paternal allele maximally produce? How do the drugs work? What other genes do they impact? For AAV gene therapy, they can help us anticipate how much UBE3A is produced in a cell. They’ve also told us a bit about how much of each UBE3A protein isoform is normally in a human neuron and where in the cell it needs to be.

You also do research on shRNA together with Ovid pharmaceuticals. Can you explain briefly how shRNA maybe one day could be used as treatment for AS?

The shRNA approach works a lot like ASOs—they cut UBE3A-ATS RNA at a specific spot. However, they can be delivered with AAV vectors, so it’s a long-lasting approach that can’t potentially over-produce UBE3A, like other types of AAV gene therapy can. It’s also a proof-of-concept for other RNA cutters that can be similarly delivered, such as miRNA, CRISPR/Cas13, and ribozymes. They all cut RNA, and can theoretically be delivered using long lasting viral vectors. Our goal for the shRNA is to use it to provide a one-time treatment that would last decades. We’ll have to be extra careful to think about safety, though because it is so long lasting.

How do you assess - from today's point of view - the future of the drug treatment of Angelman syndrome?

Like you all, I’m anxiously awaiting the results of the clinical trials for ASOs. I think we need to be patient and wait until kids of different ages have been treated with what is determined to be the best dose before we get too confident. Other therapeutic approaches, like the shRNAs, will depend on how the ASO trials go. However, I think we all should be optimistic because we have three different attempts coming up and their interest and progress has drawn other companies into Angelman therapeutics. Pharma thinks they can make a difference for kids with AS, and it’s always good to have their optimism behind the community. If the ASOs work, then there will be many trying to make better therapeutics. Better can mean many things—easier to deliver, longer lasting, or targeting a different area of the brain. I just hope that some companies and research labs continue to study ways to therapeutically help older individuals with AS who may not benefit as strongly from the ASOs and other genetic therapies.

How do you assess the developmental potential of "adult Angelman brains" in a possible future treatment?

The information inferred about this from mice is only a hint, and shouldn’t be taken too literally. Humans take much longer to develop, so it seems possible that humans would have a longer developmental window for treatment. The only way to know this for sure is to treat individuals of different ages with ASOs. I suspect that will happen by real, careful clinical trials, however, it will likely happen after trials involving younger kids have been completed. Humans can learn throughout life, so it’s possible that there will be some benefit of restoring UBE3A in older individuals, too. Then it becomes a risk versus benefit calculation.

„For the future of Angelman patients, I hope we change what it means to have a diagnosis of Angelman syndrome. I hope we can provide therapeutic options to make life easier for a child with AS and their families.“