Strategies to improve access to physical activity opportunities for people with physical disabilities.

Community-based physical activity opportunities have been shown to help adults with physical disabilities improve their participation in daily activities and reduce social isolation. Despite the known benefits, substantial barriers and challenges inhibit accessibility to these physical activity opportunities. To facilitate the co-construction of strategies to overcome accessibility issues pertaining to community-based physical activity opportunities. In total, 45 individuals with physical disabilities, patients at a rehabilitation hospital, staff members of disability organizations, staff of local or provincial government agencies/departments, kinesiologists, occupational therapists, graduate students, and peer mentors participated in one of four World Cafés held in their respective cities. World Café is a methodology for fostering collaborative, solution-focused conversation that aims to solve problems through collective intelligence. Participants were divided into groups of three to four people and invited to engage in evolving rounds of discussions responding to prompts about accessibility to physical activity in their communities. Transcripts were analyzed using content analysis. In total, 17 strategies were identified, addressing 5 areas: representation and visibility (e.g., prioritize hiring people with a disability), finances (e.g., reduce direct costs for participants), connection and social support (e.g., foster social networks that provide informational support), education and programming (e.g., enhance awareness of existing services and resources), and government programs and policies (e.g., enforce accessibility standards for indoor and outdoor spaces). The findings of this study provide strategies and practical applications for community programs and governments to consider for increasing access to physical activity opportunities for people with physical disabilities.

Adults living with physical disabilities experience numerous benefits (e.g., greater social connection and ability to complete everyday tasks) from participation in community-based physical activities. Despite the known benefits of physical activity for adults with physical disabilities, accessibility to community-based physical activity opportunities remain limited in Canada. The purpose of this study was to facilitate conversations among members of the disability and physical activity communities and co-develop strategies to improve access to community-based physical activity opportunities. In total, 45 participants in 3 Canadian cities were divided into small groups to engage in evolving rounds of discussions responding to access to physical activity in their communities. Altogether, 17 strategies targeting 5 areas related to accessibility were developed. The five areas included representation and visibility (e.g., prioritize hiring people with a disability), finances (e.g., reduce direct costs for participants), connection and social support (e.g., foster social networks that provide informational support), education and programming (e.g., enhance awareness of existing services and resources), and government programs and policies (e.g., enforce accessibility standards for indoor and outdoor spaces). The findings of this study provide practical strategies that community organizations and governments can implement to improve access to community-based physical activity opportunities for people with physical disabilities.

MOZ and Menin-MLL Complexes Are Complementary Regulators of Chromatin Association and Transcriptional Output in Gastrointestinal Stromal Tumor.

Gastrointestinal stromal tumor (GIST) is commonly characterized by activating mutations in the receptor tyrosine kinase KIT. Tyrosine kinase inhibitors are the only approved therapy for GIST, and complementary treatment strategies are urgently needed. As GIST lacks oncogene amplification and relies upon an established network of transcription factors, we hypothesized that unique chromatin-modifying enzymes are essential in orchestrating the GIST epigenome. We identified through genome-scale CRISPR screening that MOZ and Menin-MLL chromatin regulatory complexes are cooperative and unique dependencies in GIST. These complexes were enriched at GIST-relevant genes and regulated their transcription. Inhibition of MOZ and Menin-MLL complexes decreased GIST cell proliferation by disrupting interactions with transcriptional/chromatin regulators, such as DOT1L. MOZ and Menin inhibition caused significant reductions in tumor burden in vivo, with superior effects observed with combined Menin and KIT inhibition. These results define unique chromatin regulatory dependencies in GIST and identify potential therapeutic strategies for clinical application. SIGNIFICANCE: Although many malignancies rely on oncogene amplification, GIST instead depends upon epigenetic regulation of KIT and other essential genes. Utilizing genome-scale CRISPR dependency screens, we identified complementary chromatin-modifying complexes essential to GIST and characterize the consequences of their disruption, elucidating a novel therapeutic approach to this disease. This article is highlighted in the In This Issue feature, p. 1599.

Dynamics of a Staphylococcus aureus infective endocarditis simulation model.

Infective endocarditis (IE) is a serious infection of the inner surface of heart, resulting from minor lesions in the endocardium. The damage induces a healing reaction, which leads to recruitment of fibrin and immune cells. This sterile healing vegetation can be colonized during temporary bacteremia, inducing IE. We have previously established a novel in vitro IE model using a simulated IE vegetation (IEV) model produced from whole venous blood, on which we achieved stable bacterial colonization after 24 h. The bacteria were organized in biofilm aggregates and displayed increased tolerance toward antibiotics. In this current study, we aimed at further characterizing the time course of biofilm formation and the impact on antibiotic tolerance development. We found that a Staphylococcus aureus reference strain, as well as three clinical IE isolates formed biofilms on the IEV after 6 h. When treatment was initiated immediately after infection, the antibiotic effect was significantly higher than when treatment was started after the biofilm was allowed to mature. We could follow the biofilm development microscopically by visualizing growing bacterial aggregates on the IEV. The findings indicate that mature, antibiotic-tolerant biofilms can be formed in our model already after 6 h, accelerating the screening for optimal treatment strategies for IE.

Preclinical Modeling of Leiomyosarcoma Identifies Susceptibility to Transcriptional CDK Inhibitors through Antagonism of E2F-Driven Oncogenic Gene Expression.

PURPOSE: Leiomyosarcoma (LMS) is a neoplasm characterized by smooth muscle differentiation, complex copy-number alterations, tumor suppressor loss, and the absence of recurrent driver mutations. Clinical management for advanced disease relies on the use of empiric cytotoxic chemotherapy with limited activity, and novel targeted therapies supported by preclinical research on LMS biology are urgently needed. A lack of fidelity of established LMS cell lines to their mesenchymal neoplasm of origin has limited translational understanding of this disease, and few other preclinical models have been established. Here, we characterize patient-derived xenograft (PDX) models of LMS, assessing fidelity to their tumors of origin and performing preclinical evaluation of candidate therapies. EXPERIMENTAL DESIGN: We implanted 49 LMS surgical samples into immunocompromised mice. Engrafting tumors were characterized by histology, targeted next-generation sequencing, RNA sequencing, and ultra-low passage whole-genome sequencing. Candidate therapies were selected based on prior evidence of pathway activation or high-throughput dynamic BH3 profiling. RESULTS: We show that LMS PDX maintain the histologic appearance, copy-number alterations, and transcriptional program of their parental tumors across multiple xenograft passages. Transcriptionally, LMS PDX cocluster with paired LMS patient-derived samples and differ primarily in host-related immunologic and microenvironment signatures. We identify susceptibility of LMS PDX to transcriptional cyclin-dependent kinase (CDK) inhibition, which disrupts an E2F-driven oncogenic transcriptional program and inhibits tumor growth. CONCLUSIONS: Our results establish LMS PDX as valuable preclinical models and identify strategies to discover novel vulnerabilities in this disease. These data support the clinical assessment of transcriptional CDK inhibitors as a therapeutic strategy for patients with LMS.

Identification and Therapeutic Targeting of GPR20, Selectively Expressed in Gastrointestinal Stromal Tumors, with DS-6157a, a First-in-Class Antibody-Drug Conjugate.

Currently, the only approved treatments for gastrointestinal stromal tumor (GIST) are tyrosine kinase inhibitors (TKI), which eventually lead to the development of secondary resistance mutations in KIT or PDGFRA and disease progression. Herein, we identified G protein-coupled receptor 20 (GPR20) as a novel non-tyrosine kinase target in GIST, developed new GPR20 IHC, and assessed GPR20 expression in cell lines, patient-derived xenografts, and clinical samples from two institutes (United States and Japan). We studied GPR20 expression stratified by treatment line, KIT expression, GIST molecular subtype, and primary tumor location. We produced DS-6157a, an anti-GPR20 antibody-drug conjugate with a novel tetrapeptide-based linker and DNA topoisomerase I inhibitor exatecan derivative (DXd). DS-6157a exhibited GPR20 expression-dependent antitumor activity in GIST xenograft models including a GIST model resistant to imatinib, sunitinib, and regorafenib. Preclinical pharmacokinetics and safety profile of DS-6157a support its clinical development as a potential novel GIST therapy in patients who are refractory or have resistance or intolerance to approved TKIs. SIGNIFICANCE: GPR20 is selectively expressed in GIST across all treatment lines, regardless of KIT/PDGFRA genotypes. We generated DS-6157a, a DXd-based antibody-drug conjugate that exhibited antitumor activity in GIST models by a different mode of action than currently approved TKIs, showing favorable pharmacokinetics and safety profiles.This article is highlighted in the In This Issue feature, p. 1307.

HAND1 and BARX1 Act as Transcriptional and Anatomic Determinants of Malignancy in Gastrointestinal Stromal Tumor.

PURPOSE: Gastrointestinal stromal tumor (GIST) arises from interstitial cells of Cajal (ICC) or their precursors, which are present throughout the gastrointestinal tract. Although gastric GIST is commonly indolent and small intestine GIST more aggressive, a molecular understanding of disease behavior would inform therapy decisions in GIST. Although a core transcription factor (TF) network is conserved across GIST, accessory TFs HAND1 and BARX1 are expressed in a disease state-specific pattern. Here, we characterize two divergent transcriptional programs maintained by HAND1 and BARX1, and evaluate their association with clinical outcomes. EXPERIMENTAL DESIGN: We evaluated RNA sequencing and TF chromatin immunoprecipitation with sequencing in GIST samples and cultured cells for transcriptional programs associated with HAND1 and BARX1. Multiplexed tissue-based cyclic immunofluorescence and IHC evaluated tissue- and cell-level expression of TFs and their association with clinical factors. RESULTS: We show that HAND1 is expressed in aggressive GIST, modulating KIT and core TF expression and supporting proliferative cellular programs. In contrast, BARX1 is expressed in indolent and micro-GISTs. HAND1 and BARX1 expression were superior predictors of relapse-free survival, as compared with standard risk stratification, and they predict progression-free survival on imatinib. Reflecting the developmental origins of accessory TF programs, HAND1 was expressed solely in small intestine ICCs, whereas BARX1 expression was restricted to gastric ICCs. CONCLUSIONS: Our results define anatomic and transcriptional determinants of GIST and molecular origins of clinical phenotypes. Assessment of HAND1 and BARX1 expression in GIST may provide prognostic information and improve clinical decisions on the administration of adjuvant therapy.

Detection of Circulating Tumor DNA in Patients With Leiomyosarcoma With Progressive Disease.

PURPOSE: Leiomyosarcoma (LMS) is a soft tissue sarcoma characterized by multiple copy number alterations (CNAs) and without common recurrent single nucleotide variants. We evaluated the feasibility of detecting circulating tumor DNA (ctDNA) with next-generation sequencing in a cohort of patients with LMS whose tumor burden ranged from no evidence of disease to metastatic progressive disease. PATIENTS AND METHODS: Cell-free DNA in plasma samples and paired genomic DNA from resected tumors were evaluated from patients with LMS by ultra-low passage whole genome sequencing (ULP-WGS). Sequencing reads were aligned to the human genome and CNAs identified in cell-free DNA and tumor DNA by ichorCNA software to determine the presence of ctDNA. Clinical data were reviewed to assess disease burden and clinicopathologic features. RESULTS: We identified LMS ctDNA in eleven of sixteen patients (69%) with disease progression and total tumor burden over 5 cm. Sixteen patients with stable disease or low disease burden at the time of blood draw were found to have no detectable ctDNA. Higher ctDNA fraction of total cell-free DNA was associated with increasing tumor size and disease progression. Conserved CNAs were found between primary tumors and ctDNA in each case, and recurrent CNAs were found across LMS samples. ctDNA levels declined following resection of progressive disease in one case and became detectable upon disease relapse in another individual patient. CONCLUSION: These results suggest that ctDNA, assayed by a widely available sequencing approach, may be useful as a biomarker for a subset of uterine and extrauterine LMS. Higher levels of ctDNA correlate with tumor size and disease progression. Liquid biopsies may assist in guiding treatment decisions, monitoring response to systemic therapy, surveying for disease recurrence and differentiating benign and malignant smooth muscle tumors.

Enhancer Domains in Gastrointestinal Stromal Tumor Regulate KIT Expression and Are Targetable by BET Bromodomain Inhibition.

Gastrointestinal stromal tumor (GIST) is a mesenchymal neoplasm characterized by activating mutations in the related receptor tyrosine kinases KIT and PDGFRA. GIST relies on expression of these unamplified receptor tyrosine kinase (RTK) genes through a large enhancer domain, resulting in high expression levels of the oncogene required for tumor growth. Although kinase inhibition is an effective therapy for many patients with GIST, disease progression from kinase-resistant mutations is common and no other effective classes of systemic therapy exist. In this study, we identify regulatory regions of the KIT enhancer essential for KIT gene expression and GIST cell viability. Given the dependence of GIST upon enhancer-driven expression of RTKs, we hypothesized that the enhancer domains could be therapeutically targeted by a BET bromodomain inhibitor (BBI). Treatment of GIST cells with BBIs led to cell-cycle arrest, apoptosis, and cell death, with unique sensitivity in GIST cells arising from attenuation of the KIT enhancer domain and reduced KIT gene expression. BBI treatment in KIT-dependent GIST cells produced genome-wide changes in the H3K27ac enhancer landscape and gene expression program, which was also seen with direct KIT inhibition using a tyrosine kinase inhibitor (TKI). Combination treatment with BBI and TKI led to superior cytotoxic effects in vitro and in vivo, with BBI preventing tumor growth in TKI-resistant xenografts. Resistance to select BBI in GIST was attributable to drug efflux pumps. These results define a therapeutic vulnerability and clinical strategy for targeting oncogenic kinase dependency in GIST. SIGNIFICANCE: Expression and activity of mutant KIT is essential for driving the majority of GIST neoplasms, which can be therapeutically targeted using BET bromodomain inhibitors.

Peptidomimetics Targeting Protein-Protein Interactions for Therapeutic Development.

BACKGROUND: Interactions between proteins play a key role in nearly all cellular process, and therefore, its dysregulation may lead to many different types of cellular dysfunctions. Hence, pathologic Protein-Protein Interactions (PPIs) constitute highly attractive drug targets and hold great potential for developing novel therapeutic agents for the treatment of incurable human diseases. Unfortunately, the identification of PPI inhibitors is an extremely challenging task, since traditionally used small molecules ligands are mostly unable to cover and anchor on the extensive and flat surfaces that define those binary protein complexes. In contrast, large biomolecules such as proteins or peptides are ideal fits for this so-called "undruggable" sites. However, their poor pharmacokinetic properties have also limited their applications as therapeutics. In this context, peptidomimetic molecules have emerged as an alternative and viable solution to this problem, since they conserve the architectural and structural features of peptides and also exhibit substantially improved pharmacokinetic profiles. CONCLUSION: In the last decades, a wide array of chemical approaches granting access to conformationally constrained peptides with substantially improved pharmacokinetic profiles have been described, with a special focus on those affording stapled peptides and allowing large-scale macrocyclizations. These peptidomimetic molecules have been successfully applied to target a plethora of biological hosts, which highlights their promising future as novel therapeutics for the treatment of incurable human diseases.

Crystal structures of a manganese(I) and a rhenium(I) complex of a bi-pyridine ligand with a non-coordinating benzoic acid moiety.

The structures of two facially coordinated Group VII metal complexes are reported, namely: fac-bromido-[2-(2,2'-bipyridin-6-yl)benzoic acid-κ2N,N']tricarbonyl-manganese(I) tetra-hydro-furan monosolvate, [MnBr(C17H12N2O2)(CO)3]·C4H8O, I, and fac-[2-(2,2'-bipyridin-6-yl)benzoic acid-κ2N,N']tricarbonyl-chlorido-rhenium(I) tetra-hydro-furan monosolvate, [ReCl(C17H12N2O2)(CO)3]·C4H8O, II. In both complexes, the metal ion is coordinated by three carbonyl ligands, a halide ion, and a 2-(2,2'-bipyridin-6-yl)benzoic acid ligand, in a distorted octa-hedral geometry. In manganese complex I, the tetra-hydro-furan (THF) solvent mol-ecule could not be refined due to disorder. The benzoic acid fragment is also disordered over two positions, such that the carb-oxy-lic acid group is either positioned near to the bromide ligand or to the axial carbonyl ligand. In the crystal of I, the complex mol-ecules are linked by a pair of C-H⋯Br hydrogen bonds, forming inversion dimers that stack up the a-axis direction. In the rhenium complex II, there is hydrogen bonding between the benzoic acid moiety and a disordered co-crystallized THF mol-ecule. In the crystal, the mol-ecules are linked by C-H⋯Cl hydrogen bonds, forming layers parallel to (100) separated by layers of THF solvent mol-ecules.