Rescue of STXBP1 encephalopathies with small molecules in mouse models in vivo

Awardee: Jacqueline Burré

Institution: Weill Medical College of Cornell University

Grant Amount: $80,070

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Mutations in STXBP1 lead to nerve cell dysfunction in the brain due to a reduction in functional STXBP1 amount. We had previously identified three small molecules (4-phenylbutyrate and two novel compounds) that restore nerve cell function in cultured mouse nerve cells and in live worm disease models. Yet, if and to what extent these small molecules revert the dysfunction in a brain remains unknown. Plus, it remains unclear if there is a critical period for when treatment needs to start, necessitating studies in a mouse model. We have established a mouse line with half of STXBP1 amount and are in the process of generating two additional mouse lines with missense mutations in STXBP1. We will use these mouse models of STXBP1 disorder to test the effect of our three small molecules in living animals. We will measure changes in seizure frequency, learning and memory, anxiety, hyperactivity and general movement, in addition to brain structure and development. To reveal if there is a critical period for when treatment needs to be started, we will determine the efficiency of the three small molecules in reversing the identified dysfunction when given to mice in utero, to newborn mice or to adolescent mice. Our study is significant because it further dissects the disease mechanism in a living animal, and because of its translational importance. Importantly, our studies will go hand-in-hand with the on-going 4-phenylbutyrate clinical trial at Weill Cornell Medicine, to achieve the most effect with the least amount of drug.

A novel mouse model for developing therapeutic approaches of STXBP1 encephalopathy

Awardee: Mingshan Xue

Institution: Baylor College of Medicine

Grant Amount: $80,070

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

STXBP1 encephalopathy is a severe neurodevelopmental disorder caused by heterozygous pathogenic variants in syntaxin-binding protein 1 (STXBP1). Both protein haploinsufficiency and dominant-negative mutations were identified as the disease mechanisms. Models of haploinsufficiency have been developed and validated and are currently being used to test potential disease-modifying therapies. However, dominant-negative mutations may require therapeutic approaches that are different from those for haploinsufficiency. Mammalian models carrying dominant-negative mutations are currently lacking. Thus, this project aims to develop and validate a new mouse model carrying a dominant-negative missense variant to fill this critical gap. This model will provide a new tool for preclinical evaluations of different therapies of STXBP1 encephalopathy and lead to a better understanding of the disease pathogenesis.

CXCL13 as a novel biomarker and therapeutic target in idiopathic multicentric Castleman disease

Awardee: David Fajgenbaum

Institution: University of Pennsylvania

Grant Amount: $64,205

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Idiopathic multicentric Castleman disease (iMCD) is a poorly understood disorder involving lymphoproliferation and multiple organ failure due to a cytokine storm often involving interleukin-6 (IL-6). Its causes, key immune cell types, signaling pathways, and cytokines involved in the disease are poorly understood. Diagnosis is challenging due to lack of a positive diagnostic biomarker and management is suboptimal due to a lack of indicators of response and novel therapeutic approaches. Annual US incidence is ~1000 individuals of all ages, and 5-year survival is estimated at 65-75%. Few treatment options exist beyond cytotoxic chemotherapies for the 50-66% of patients who do not respond to the only FDA-approved therapy, siltuximab, which blocks IL-6. Advances in discovering treatments, diagnostic biomarkers, and indicators of response to siltuximab are critically needed. We recently identified the chemokine CXCL13 as a potential, novel biomarker and therapeutic target in iMCD. CXCL13 is critical to maintaining lymph node morphology as well as developing appropriate adaptive immune responses, both of which are abnormal in iMCD. In a pilot study, we found that CXCL13 is the most elevated circulating cytokine in iMCD patients and that CXCL13 expression is increased in iMCD lymph node tissue (Pierson et al, AJH, 2018). Proteomic profiling of serum from 88 iMCD patients revealed CXCL13 to be the most elevated cytokine compared to healthy controls and, further, it decreases rapidly in siltuximab responders upon administration but remains elevated in siltuximab non-responders (unpublished). The overall goal of this project is to investigate CXCL13 as a possible diagnostic biomarker, indicator of response to therapy, and/or therapeutic target for iMCD. These goals directly align with one of the top priority research questions outlined on the RFA (“What is the role of CXCL13 in iMCD?”). The specific aims of this project are to (1) quantify CXCL13 expression in iMCD lymph node tissue to assess the diagnostic applicability of this test for iMCD and to determine the cellular source of CXCL13, (2) quantify CXCL13 levels in serum to determine a threshold for serum CXCL13 as a potential diagnostic test or a clinical indicator biomarker of response to siltuximab, and (3) assess the in vitro effects of CXCL13 on circulating immune cells from iMCD patients. These studies will improve understanding of iMCD biology and may translate into more effective and personalized therapies and biomarkers that will have a transformative impact. Thank you for your consideration.

Leveraging proteostasis to improve Niemann-Pick C gene therapy

Awardee: Mark Schultz

Institution: Regents of the University of Michigan

Grant Amount: $50,010

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Niemann-Pick C is a genetically inherited disease caused by an abnormal accumulation of cholesterol. This cholesterol build-up commonly occurs due to a defect in a gene called NPC1. In Niemann-Pick C mouse models, adding back a fully functional NPC1 gene via gene therapy improves but does not fully correct the disease. Here we will leverage the information we have gained on protein folding to significantly increase the efficacy of Niemann-Pick C gene therapy.

Natural History of the Hyperinsulinism Hyperammonemia Syndrome – A Multi-center Observational Study Incorporating Patient-centered Data through the HI Global Registry

Awardee: Elizabeth Rosenfeld

Institution: Children's Hospital of Philadelphia

Grant Amount: $73,045

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Congenital hyperinsulinism (HI) is a rare genetic disorder that causes low blood sugar. The second most common genetic form of hyperinsulinism is the hyperinsulinism hyperammonemia (HI/HA) syndrome. Individuals with HI/HA syndrome develop low blood sugar after fasting and after eating protein-rich foods. HI/HA syndrome is also associated with high blood concentrations of ammonia, characteristic seizures, and learning and behavioral problems. Low blood sugar in HI/HA syndrome is treated with dietary modification and a medication called diazoxide, Studies have shown that the severity of low blood sugar in other (ie: non-HI/HA) forms of HI treated with diazoxide can improve with time – many individuals are able to discontinue diazoxide, or decrease the dose, as they age. There have been isolated reports documenting resolution of low blood sugar and seizures in individuals with HI/HA syndrome. However, studies describing the typical trajectory of disease over time in HI/HA syndrome are lacking. Closing this knowledge gap is an important first step toward individualizing therapy, establishing standards of care, and improving patient outcomes. We propose a multi-center, multimodal approach to describe the natural history of the HI/HA syndrome. Data will be obtained through both medical chart review and telephone interview of patients with HI/HA syndrome followed by the Hyperinsulinism Centers at the Children’s Hospital of Philadelphia and Cook Children's Health Care System. The HI Global Registry will additionally be utilized as a source for collection of detailed, patient-level data. Primary outcomes will include the frequency of diazoxide discontinuation and seizure resolution in individuals with HI/HA syndrome. The relationship between these outcomes and other assessed patient characteristics will be explored. We will also explore the utility of this multi-prong approach to examine the natural history of different HI subtypes. Ultimately, by combining clinical data and patient perspectives, we aim to develop a deeper understanding of the natural history of the HI/HA syndrome that will lead to improved patient outcomes.

Evaluating the Effects of Selected Small-Molecules on a Zebrafish Model of TBCK Syndrome

Awardee: Gerald B. Downes

Institution: University of Massachusetts Amherst

Grant Amount: $50,400

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

TBCK Syndrome is a rare, poorly understood, severe neurological disease. In 2016 multiple publications first reported that mutations in the TBCK gene result in a progressive loss of muscle tone, intellectual disability, characteristic facial features, drug resistant epilepsy, and a high incidence of childhood or adolescent mortality. Outside of managing symptoms, there are currently no treatments to slow the progression of the disease. Animal models are often a key step towards better understanding a disease and developing new therapeutics, however there are currently no published animal models of TBCK Syndrome. Zebrafish are a widely used disease model due to several advantageous features, which also make this an excellent system to evaluate or screen for new therapeutic drugs. My laboratory is establishing a zebrafish model of TBCK Syndrome, and we have already created multiple tbck mutant lines and identified a phenotype. Our goals here are to continue characterizing the effects of tbck mutation on the zebrafish nervous system and to evaluate whether any of three different small-molecules, already FDA approved or known to be safe for human consumption, decrease the severity of tbck-mutant phenotypes. The completion of this project will establish a foundation to use zebrafish for small-molecule screens and help determine whether any of these compounds should be further investigated as a treatment for TBCK Syndrome.

Identify genetic regulatory circuitry driving the development of rapamycin tolerance

Awardee: Yan Tang

Institution: Brigham and Women's Hospital

Grant Amount: $73,491

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Rapamycin (and its analogues, rapalogs) are the only effective treatment for TSC-associated diseases, including lymphangioleiomyomatosis (LAM). However, rapalogs can only stabilize lung function in LAM, but lung function continues to decline upon treatment cessation. It’s of paramount importance to understand the mechanisms of why and how LAM cells can survive rapamycin treatment and regrow after treatment cessation. Our single cell RNA-seq analysis of five LAM and six AML (angiomyolipoma, kidney manifestation of TSC) samples identified a subset population of LAM/AML cells with elevated stemness and dormancy programs, two typical features of drug tolerant/resistant tumor persister cells. These cells exhibited stabilized tumor cell phenotypes upon rapamycin treatment, including maintaining high expression of many TSC marker genes, suggesting a rapamycin tolerance mechanism. To identify drivers of development of rapamycin tolerance in a heterogeneous population, we have adopted a high-complex barcoding lineage tracing system that enables simultaneous assessing of each cell’s origin/lineage and transcriptomic/epigenomic profiles at single cell level. This novel approach will enable us to identify lineage-specific drivers for the development of rapamycin tolerance.

Identifying SETBP1 haploinsufficiency molecular pathways to improve patient diagnosis and treatment.

Awardee: Vanessa Fear

Institution: Telethon Kids Institute, University of Western Australia

Grant Amount: $45,733

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

SETBP1 haploinsufficiency disorder presents with intellectual disability, speech impairment and development delay, among other symptoms. There is little information regarding SETBP1 haploinsufficiency disorder and the cellular pathways that lead to disease. This study will use CRISPR gene editing and stem cell neural disease modelling to elucidate cellular pathways that contribute to SETBP1 haploinsufficiency disorder, and identify new treatments.

Toward Structure-based Drug-Discovery for SETBP1

Awardee: Jerome Baudry

Institution: The University of Alabama in Huntsville

Grant Amount: $45,733

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

We will start the first drug discovery pipeline toward finding a pharmaceuticals that can counter the effect of SETBP1 mutations. We will use very powerful computers to predict how mutated SETBP1 interacts with its partners in the cell, and we will identify small molecules that can correct the problems.

Exercise as Medicine in Cystic Fibrosis: A pilot study assessing the impact of a telehealth exercise program on adherence and self-efficacy

Awardee: Stefanie Krick

Institution: The University of Alabama at Birmingham

Grant Amount: $117,655

Funding Period: February 1, 2022 - January 31, 2023

Targeting the shelterin component TINF2 in telomere diseases

Awardee: Suneet Agarwal

Institution: Boston Children's Hospital

Grant Amount: $65,445

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Telomere biology disorders (TBDs) affect multiple parts of the body, including the blood, lungs, liver and bones. There are no effective treatments that address the life-threatening problems. Telomeres are the ends of chromosomes that ensure ability of cells to keep dividing to replace damaged cells with new healthy ones. In TBDs, genetic mutations reduce telomere length and thus cells cannot regenerate themselves, and the tissues fail causing disease. By studying a particular mutation, we have found that decreasing a protein called TIN2 can increase telomere length in TBD patient cells. In this proposal we will study in depth whether reducing TIN2 could be a viable strategy to restore telomeres in the setting of various mutations that cause TBDs, and also test whether chemicals can be used to achieve this effect. These studies could provide a new therapeutic strategy that could be applied throughout the body for patients with TBDs.

Identification and signaling characterization of GNASR201H/C selective inhibitors for FD/MAS

Awardee: Edward Hsiao

Co-PI: Kelly Wentworth

Institution: University of California, San Francisco

Grant Amount: $53,791

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Fibrous dysplasia and McCune Albright syndrome (FD/MAS) are severe congenital conditions caused by activating point mutations in the GNAS gene; however, specific molecular tools for directly perturbing GNAS activity in a mutation specific fashion are largely lacking. The overall goal of this proposal is to complete the analysis of a series of promising compounds that we previously identified as likely to specifically bind GNASR201H. We will use a novel human induced pluripotent stem cell model carrying the GNASR201H mutation in the endogenous locus to test our top drug candidates for their ability to block the abnormal cAMP production, and also use physical assays to determine if the inhibition occurs through direct binding to GNAS or by acting on a downstream pathway component. This proposal directly addresses critical needs by identifying promising molecular tools for dissecting GNASR201H function and serving as scaffolds for developing novel therapeutics that directly target GNAS mutations that cause FD/MAS, and validating a new human IPS cell model that will be useful for studies of cellular differentiation and function in FD/MAS. All reagents, compounds, cell lines, and analytical methods are already available through the collaborators and experienced team.

Structure activity relationship studies of compounds to treat FD/MAS

Awardee: Fernando Fierro

Co-PI: Charles Hoffman

Institution: University of California Davis

Grant Amount: $53,791

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

FD lesions contain cells with excess G alpha protein activity that stimulates adenylyl cyclases (ACs), increasing cAMP levels. This disruption of appropriate cell signaling ultimately affects normal bone homeostasis. We propose testing a set of compounds with promising AC-inhibitory activity, with the ultimate goal of developing a therapeutic drug. Our proposal is a collaborative effort among different research groups: Dr. Fierro will identify compounds that reverse GNAS(R201H) or GNAS(R201C) effects in human bone marrow stromal/stem cells. Dr. Hoffman will use yeast to elucidate if the compounds act directly or indirectly on ACs. Dr. Inglese will perform in vitro pharmacokinetic studies with the same compounds.

Unraveling the role of Adiponectin-expressing bone marrow stromal cells in the cellular pathogenesis of Fibrous Dysplasia

Awardee: Biagio Palmisano

Institution: Sapienza University of Rome

Grant Amount: $53,791

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

We have previously shown that osteoclasts, the cells that normally destroy damaged bone to allow its regeneration, play a major role in the appearance and evolution of Fibrous Dysplasia (FD). We know that in growing FD lesions, the number of osteoclasts is abnormally high due to the production of a factor named RANKL by the pathological tissue. However, what we do not know yet is who produces RANKL at the very beginning of the disease, when osteoclasts destroy the healthy bone that will be then replaced by the pathological tissue. Recently, by generating a new Gs(alpha) transgenic mouse model, we have identified the cell type that is involved in this early phase of the disease. In this project, we want to investigate the characteristics of this cell type and the mechanisms through which it produces RANKL, both in the absence and in the presence of the Gs(alpha) mutation. Understanding these points may allow the development of therapies that act specifically on the very first trigger of FD lesions.

Reversing Brain Iron Overload in BPAN by a Natural Small Molecule

Awardee: Young-Ah Seo

Institution: University of Michigan

Grant Amount: $66,366

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

The overall goal of this project is to develop new therapeutic strategies that can reduce brain iron overload and iron-induced neurodegeneration in BPAN patients. We have identified that a natural small molecule is exceptionally effective at promoting iron transport. We have now found that iron accumulates in the BPAN cell model and that the resulting iron overload can be mitigated by this small molecule. Building on these preliminary results, this proposal will extensively characterize the capacity for a small molecule to mobilize excess iron from inside cells and will test the overarching hypothesis that small molecule-mediated iron mobilization can mitigate neuronal cell death in BPAN cell models and patient-derived primary fibroblast cells. Completion of the proposed research will advance our fundamental understanding of the mechanistic underpinnings of brain iron overload in BPAN and will build a foundation for the potential therapeutic use of small molecule mobilizers of intracellular iron.

Membrane homeostasis as potential therapeutic angle in Cohen Syndrome

Awardee: Jens Luders

Institution: Institute for Research in Biomedicine, Barcelona, Spain

Grant Amount: $47,161.00

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Cohen Syndrome is a rare disease caused by mutations in the VPS13B gene. Patients affected by this disease are born with several disabilities and health problems. For example, children with Cohen Syndrome may develop slowly, have a small head size, intellectual disability, and an overall weak muscle tone. They frequently suffer from a reduction in the number of certain blood cells, which increases the risk of infections, and loss of vision, which becomes worse with age and can lead to blindness. Unfortunately, there is no treatment available for these patients. Since the molecular and cellular functions of the VPS13B gene are still poorly understood, it is unclear how its mutation leads to Cohen Syndrome. This makes it impossible to develop a treatment or therapy. We have recently obtained preliminary data suggesting that Cohen Syndrome may involve defects in primary cilia, hair-like structures on the surface of cells that function as a cell's antenna. They allow cells to receive and respond to signals from their environment and are very important for various developmental processes including formation of the brain and the retina. In this project we will uncover how defects in VPS13B may affect cilium formation and function in three different model systems: cultured cells including cells obtained from Cohen Syndrome patients, retinal tissue grown in a culture dish from patient cells, and zebrafish embryos, which recapitulate many developmental processes that also occur in humans including brain and eye development. Using the same model systems, we will then test if culture supplements or pharmacological treatments may be used to repair ciliary defects. If so, these treatments may be further developed into therapies in the future.

Determination of pathomechanisms and assessment of therapeutic strategies for Cohen Syndrome in patient derived cells and a murine model

Awardee: Muhammad Ansar

Institution: Jules-Gonin Eye Hospital, Ophthalmology Department of the University of Lausanne, Lausanne, Switzerland

Grant Amount: $$115,000

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Cohen Syndrome (CS) is a rare genetic disease caused by the loss of function of the gene called VPS13B. Individuals with CS suffer from developmental, intellectual, motor, metabolic, immunologic and progressive vision loss problems. In this project we proposed to study and understand how the VPS13B gene functions and how the loss of this gene causes the disease symptoms. At the same time we’ll try to explore and test various treatment options by using cellular and mouse models, with the aim to ultimately find the cure for the CS disease or to at least stop the progressive loss of vision in these patients. Treatment strategies include the use of chemical drugs as well as gene therapy.

High Resolution Ventilation and Perfusion MRI Assessment of Neuroendocrine Cell Hyperplasia of Infancy (NEHI) in Infants and Young Children: Technical Feasibility and Direct Clinical Application

Awardee: Katie Krone

Institution: Boston Children's Hospital

Grant Amount: $41,000

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Neuroendocrine cell hyperplasia of infancy (NEHI) is a type of childhood lung disease that is very challenging to diagnose because of the lack of specific disease features. Clinical and radiologic features may overlap with other types of lung disease affecting children. Currently, clinicians rely on imaging with high-resolution chest computed tomography (HRCT) and/or tissue diagnosis by surgical lung biopsy in order to identify NEHI in patients who have suggestive clinical signs and symptoms. This diagnostic approach poses risks to the vulnerable pediatric population. HRCT exposes infants and children to potentially harmful ionizing radiation, and often requires sedation to obtain adequate images in younger children. There are also some concerns about the effects of general anesthesia on the developing brain. An additional problem is that HRCT scans are often not specific enough to be diagnostic of NEHI. Given the potential risks of exposure to radiation and anesthesia, and the limitations of HRCT interpretation, new diagnostic strategies are needed that provide insight into the pathophysiology of NEHI, ensure timely, safe and accurate diagnostic information, and improve patient care. High-resolution ventilation and perfusion MRI is new attractive alternative that overcomes the limitations and risks of HRCT and has the potential to provide improved diagnostic information. Thus, the main objective of this study is to prospectively investigate the technical feasibility and clinical utility of high-resolution ventilation and perfusion MRI in infants and young children with clinically suspected or confirmed NEHI.

Spatial Transcriptomics to Identify Cellular Alterations in NEHI

Awardee: W. Adam Gower

Institution: University of North Carolina at Chapel Hill School of Medicine

Grant Amount: $41,000

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

The diagnosis and management of NEHI is complicated by a lack of understanding about the biologic processes at work in the lungs of affected children. Research so far has suggested that NEHI is unique from other forms of childhood interstitial lung disease, and likely involves abnormal function of neuroendocrine cells and other cell types in the smallest airways. We propose to utilize a new technology that will allow use to determine what genetic pathways and biological processes are unique to NEHI lung tissue, using excess lung biopsy material that has already been collected and banked. By understanding which genetic pathways and processes are unique to NEHI compared to children with other lung diseases and healthy controls, we may identify ways to improve diagnosis and perhaps targets for new and unique treatments. Our team has extensive expertise in NEHI and rare lung disease research, access to tissues samples for use, and colleagues who can assist in the analyses needed to complete this project during the award period.

Targeting mTOR signaling to improve neurologic outcomes in MSUD

Awardee: Rebecca Ahrens-Nicklas

Institution: The Children's Hospital of Philadelphia and The University of Pennsylvania

Grant Amount:

Funding Period: February 1, 2022 - January 31, 2023

---

Summary:

Maple Syrup Urine Disease arises from a defect in branched chain amino acid metabolism (BCAA), that leads to toxic increases in certain amino acids throughout the body. Dietary therapy and liver transplantation can improve levels of BCAAs; however, unfortunately, patients still have neurocognitive and psychiatric symptoms. Based on work in a mouse model of MSUD, we believe that an inability to use BCAAs as fuel in the brain changes mTOR signaling, an important pathway for neurodevelopment. Other disorders with abnormal mTOR activation are known to result in learning difficulties and psychiatric symptoms. In this application, we plan to study how abnormal mTOR signaling affects the brain in MSUD and to explore new therapeutic approaches aimed at correcting this difference.