Patient-derived Cell Models Research Articles

DDDR-32. EVALUATING THE THERAPEUTIC EFFECTS OF SMALL MOLECULE INHIBITORS OF CDK4/6 AND FAK IN PRECLINICAL MENINGIOMA MODELS

Abstract BACKGROUND New therapies are needed for meningioma since treatment options are limited once patients have exhausted surgery and radiation. FAK, CDK4/6 and RAF/MEK represent potential targets because of synthetic lethality with NF2, loss of CDKN2A, and activation of MAPK signaling pathway in meningioma, respectively. The objective of this study was to evaluate the efficacy of targeting FAK, CDK4/6 and RAF/MEK as monotherapies and combination therapies in traditional and patient-derived cell lines and xenografts. METHODS In vitro, cell viability and proliferation assays were used to test abemaciclib (CDK4/6 inhibitor), defactinib (FAK inhibitor) and VS-6766 (RAF/MEK inhibitor) as monotherapy and in combination. To better recapitulate the meningioma microenvironment, targeted agents were evaluated with Matrigel, an artificial extracellular matrix. The efficacy of VS-4718 (in vivo formulation of defactinib) and abemaciclib were evaluated in a subcutaneous IOMM-lee meningioma model (having CDKN2A loss) in nude mice. Furthermore, we are establishing cell cultures and patient-derived cell and xenograft (PDX) models using freshly-resected tissue from patients with recurrent or high-grade (WHO grade 2-3) meningiomas. RESULTS In vitro evaluation identified the combination of defactinib with abemaciclib resulted in a synergistic decrease in cell viability relative to each monotherapy alone, while the combination of defactinib+VS-6766 was not beneficial. The presence of Matrigel enhanced the sensitivity of all three agents. In vivo, we observed improved survival in mice treated with abemaciclib vs control (45 days vs 26 days; p=0.03), as well as combination of VS-4718 + abemaciclib vs control (44 days vs 26 days; p=0.04, Gehan-Breslow-Wilcoxon test). We did not observe survival extension with VS-4718 monotherapy. Lastly, we successfully established an orthotopic meningioma PDX using a WHO Grade 3 tumor for evaluation of novel therapies in meningioma. CONCLUSION Abemaciclib showed promising efficacy in preclinical meningioma xenografts with CDKN2A loss. Studies to evaluate these therapies in other orthotopic models are underway.

CNSC-15. MITOCHONDRIA TRANSFER VIA GLIOMA-ASTROCYTE NETWORK MICROTUBES REPROGRAMS TUMOR CELLS FOR ENHANCED TUMORIGENICITY

Abstract Glioblastoma (GBM) interaction with neural cells is critical to its pathobiology. Emerging evidence suggests that GBM cells form an interconnected network with astrocytes, facilitating tumor persistence. Given reports of intercellular transfer of mitochondria in ischemic stroke and other pathologic disease states outside the CNS, we hypothesized that this network facilitates mitochondria transfer from astrocytes to GBM with protumorigenic sequelae. Employing transgenic mice and intracranial viral vector transductions in rats, we found that mitochondria transfer from the TME to GBM occurs in intracranial mouse and patient-derived xenograft models (in nude rats) of GBM. Mitochondria transfer from bone marrow-derived immune cells was minimal in bone marrow chimera mouse models of orthotopic GBM, suggesting that neural cells were the primary mitochondria donors. We confirmed this in vitro, where mouse astrocytes were the major mitochondria donors, followed by microglia and to a much smaller extent bone marrow-derived macrophages. Immortalized human astrocytes transduced with mitochondria-localized mCherry (mito-mCherry) also transferred their mitochondria to numerous patient-derived glioma stem cell (GSC) models at rates of ~5-20%, assessed by flow cytometry and confocal microscopy. Mitochondria were visualized along intercellular actin bridges, structurally resembling tumor microtubes. Blocking actin polymerization or knocking down GAP43 (previously linked to microtube formation) decreased mitochondria transfer from astrocytes to GBM in vitro. Functionally, sorted mito-mCherry+ patient-derived GSCs displayed higher mitochondrial respiration, metabolomic reprogramming and proliferation-promoting phospho-signaling. Mito-mCherry+ GBM cells were more likely to be in the proliferative G2/M phases of the cell cycle, and when sorted from co-cultures had high self-renewal (in vitro) and tumor-initiating capacity (in vivo xenograft mouse model). In ongoing work, we are investigating the role of retrograde GBM to astrocyte transfer of mitochondria by dual-color labeling of the organelle, as well as further delineating the protein machinery involved in this fundamental protumorigenic process, with the goal of identifying novel therapeutic targets.

EXTH-54. GB13 IS A POTENT TREATMENT FOR IL13RA2-EXPRESSING GBM AND DMG AND IMPROVES STANDARD-OF-CARE THERAPY

Abstract GB13 is a novel biologic therapy in the final stages of preclinical development for the treatment of glioblastoma (GBM) and H3 K27-altered diffuse midline glioma (DMG) that has received Orphan Drug Designation by the Food and Drug Administration for treatment of malignant gliomas. GB13 targets a specific tumor-restricted receptor of interleukin 13 called interleukin 13 receptor alpha 2 (IL13Rα2). IL13Rα2 is highly expressed in malignant gliomas and, importantly, is not expressed on non-cancerous cells of the brain. GB13 consists of an engineered proprietary mutant of IL13, which binds exclusively to IL13Rα2, and is fused to a highly cytotoxic exotoxin molecule. In vitro data demonstrate that GB13 potently kills IL13Rα2+ cancer cells while sparing non-cancerous cells. These characteristics make GB13 an attractive agent for safe and efficacious targeting of tumor cells expressing IL13Rα2 in upcoming clinical trials. In the current studies, we employed patient-derived GBM and DMG cell and animal models to provide key conclusions that support GB13 as an effective treatment option for gliomas in the clinic. First, we demonstrated that single acute infusions of GB13 by enhanced delivery (CED) is effective at decreasing orthotopic tumor volumes and increasing animal survival and that a long-term infusion can more significantly extend animal survival. Second, we determined that IL13Rα2 is requisite for GB13 activity as tumors that do not express the receptor are insensitive to the cytotoxic effects of GB13, demonstrating a precise and clear biomarker for clinical trial patient selection. Finally, we determined that GB13 works in concert with clinical standard-of-care radiation therapy to increase cell death, compared to radiation alone. Based on this work, we and our clinical collaborators are confident that the current work confirms GB13 has many important characteristics as an exciting therapy, which continues development towards a Phase I clinical trial for both GBM and pediatric DMG.

MODL-11. EXPLORING THE THERAPEUTIC POTENTIAL OF YAP-TEAD INHIBITORS FOR TARGETING GBM CELL MIGRATION AT THE INFILTRATIVE MARGIN

Abstract Glioblastoma (GBM) is an aggressive brain tumor with a median overall survival of only 12-15 months. Despite remarkable cellular and molecular heterogeneity, all GBM subtypes exhibit an infiltrating growth pattern which leads to incomplete surgical resection and inevitable recurrence, representing a major obstacle for effective treatment and an unmet need for therapy. Our research project aims to investigate the efficacy of YAP-TEAD inhibitors, including Verteporfin (VP), on migratory properties of GBM cells at the interface between the tumor core and the infiltrative tumor margin. Recently, several groups have implicated Hippo pathway YAP-TEAD activation in GBM growth and mesenchymal transition, and our laboratory demonstrated anti-migration and anti-invasion efficacy of the YAP-TEAD inhibitor VP across GBM subtypes, in patient-derived cell and xenograft (PDX) mouse models. Here we set to develop an ex vivo model for high-throughput testing of various YAP-TEAD inhibitors using organotypic slice cultures obtained from PDX and primary glioblastoma resection specimens, focusing on tumor areas around the infiltrative margin. Tumor cells within 250µ-thick organotypic slices were infected with GFP labeled retrovirus and subjected to confocal time-lapse imaging 72-96 hours later. Slices were treated first with vehicle (DMSO) for 4 hours, and subsequently with the YAP-TEAD inhibitor VP for 4 hours. To assess drug impact on tumor cell migration, we gathered imaging data on migration properties such as speed and directionality. Analysis of a PDX model generated from a de-novo GBM surgical resection (G-17969) revealed significantly decreased distance traveled in GFP+ cells treated with VP, compared to DMSO (p-value = 0.0002, n=50 cells). These pilot results corroborate other studies demonstrating anti-invasion properties of VP, contributing towards our goal of establishing a preclinical pipeline for rapid, high-throughput screening of anti-invasion drug inhibitors ex vivo. Key words: Glioblastoma, cell migration, YAP-TEAD inhibitors, time-lapse imaging

Abstract 18778: Patient-Derived Stem Cell Models of Pediatric Restrictive Cardiomyopathy Exhibit Increased Resting Tension and Cardiomyocyte Calcium Sensitivity

Introduction: Pediatric Restrictive Cardiomyopathy (RCM) is a genetic cardiomyopathy resulting from profoundly increased stiffness of the wall of the cardiac ventricle with normal or low normal contractility. Treatment options are limited, with most patients necessitating heart transplant. Therapies that can improve diastolic function are needed for this severe disease. However, development of novel therapies has been limited by a paucity of models of this rare disease. Here, we develop two novel models of pediatric RCM and use novel high-throughput functional analysis to measure diastolic dysfunction and defects in calcium handling. Hypothesis: Patient-derived human induced pluripotent stem cell (hiPSC) models of pediatric RCM will exhibit increased resting tension indicative of diastolic dysfunction, as well as increased calcium sensitivity. Methods: Cardiomyocytes were differentiated from hiPSCs derived from two pediatric patients with RCM, as well as a paired isogenic CRISPR-corrected lines. Cells were replated onto polyacrylamide gels and stained with calcium sensitive dyes, and contractility, resting tension, and calcium sensitivity were measured using a novel high-throughput functional imaging platform. Results: RCM cells from both patients showed elevated contractility, resting tension, and calcium sensitivity compared to their isogenic controls. Conclusions: Patient-derived RCM cells show alterations in calcium sensitivity and resting tension that recapitulate and explain the diastolic dysfunction seen in patients. These lines, combined with the high-throughput measurement platform described here, will provide a powerful platform for exploring novel therapeutic strategies for this severe disease.

777P Targeting cadherin-6 in epithelial ovarian cancer: Clinical significance of its expression and efficacy of raludotatug deruxtecan (R-DXd) in patient-derived cell models

777P Targeting cadherin-6 in epithelial ovarian cancer: Clinical significance of its expression and efficacy of raludotatug deruxtecan (R-DXd) in patient-derived cell models

Patient-Derived Cellular Models for Polytarget Precision Medicine in Pantothenate Kinase-Associated Neurodegeneration.

The term neurodegeneration with brain iron accumulation (NBIA) brings together a broad set of progressive and disabling neurological genetic disorders in which iron is deposited preferentially in certain areas of the brain. Among NBIA disorders, the most frequent subtype is pantothenate kinase-associated neurodegeneration (PKAN) caused by pathologic variants in the PANK2 gene codifying the enzyme pantothenate kinase 2 (PANK2). To date, there are no effective treatments to stop the progression of these diseases. This review discusses the utility of patient-derived cell models as a valuable tool for the identification of pharmacological or natural compounds for implementing polytarget precision medicine in PKAN. Recently, several studies have described that PKAN patient-derived fibroblasts present the main pathological features associated with the disease including intracellular iron overload. Interestingly, treatment of mutant cell cultures with various supplements such as pantothenate, pantethine, vitamin E, omega 3, α-lipoic acid L-carnitine or thiamine, improved all pathophysiological alterations in PKAN fibroblasts with residual expression of the PANK2 enzyme. The information provided by pharmacological screenings in patient-derived cellular models can help optimize therapeutic strategies in individual PKAN patients.

Research prospect of preclinical model construction and precision therapy in ameloblastoma

Ameloblastoma (AM) is a benign odontogenic tumor with unknown etiology. It is prone to recurrence and has a potential for malignant transformation. Patients often show high rates of relapse after curettage, or suffer from structural and functional damage of jaw after partial resection. Whole-genome sequencing data revealed that BRAF mutations and SMO mutations were common and likely to be mutually exclusive in AM. It was also reported that BRAF inhibitors were effective in several patients carrying BRAFV600E mutation. However, reliable preclinical models are urgently needed for exploring targeted therapy as it's so difficult to conduct large clinical trials in this tumor. Patient-derived cell models in vitro and xenograft models in vivo are frequently used preclinical models. In fact, benign tumor cells generally showed a finite proliferative capacity in two-dimensional culture, and most likely, they could exhibit altered cellular phenotype after immortalization. Moreover, this benign tumor presented low chances of subcutaneous engraftment in nude mice. Accordingly, humanized mouse xenograft model needs more exploration. Yet, it is worth mentioning that a three-dimensional organoid model presents a high potential in culturing stem-cell-like epithelial cells in AM, and it would further be used in recapitulating corresponding tumors and developing targeted medicines. In this paper, we review research progress in preclinical models and the genetic variations of AM, and raise drug screening prospect of the current organoid models, which may pave the way for the possible personalized medicine in AM.

Prediction of mechanistic subtypes of Parkinson’s using patient-derived stem cell models

Parkinson’s disease is a common, incurable neurodegenerative disorder that is clinically heterogeneous: it is likely that different cellular mechanisms drive the pathology in different individuals. So far it has not been possible to define the cellular mechanism underlying the neurodegenerative disease in life. We generated a machine learning-based model that can simultaneously predict the presence of disease and its primary mechanistic subtype in human neurons. We used stem cell technology to derive control or patient-derived neurons, and generated different disease subtypes through chemical induction or the presence of mutation. Multidimensional fluorescent labelling of organelles was performed in healthy control neurons and in four different disease subtypes, and both the quantitative single-cell fluorescence features and the images were used to independently train a series of classifiers to build deep neural networks. Quantitative cellular profile-based classifiers achieve an accuracy of 82%, whereas image-based deep neural networks predict control and four distinct disease subtypes with an accuracy of 95%. The machine learning-trained classifiers achieve their accuracy across all subtypes, using the organellar features of the mitochondria with the additional contribution of the lysosomes, confirming the biological importance of these pathways in Parkinson’s. Altogether, we show that machine learning approaches applied to patient-derived cells are highly accurate at predicting disease subtypes, providing proof of concept that this approach may enable mechanistic stratification and precision medicine approaches in the future.

Novel Strategies in the Early Detection and Treatment of Endothelial Cell-Specific Mitochondrial Dysfunction in Coronary Artery Disease.

Although elevated cholesterol and other recognised cardiovascular risk factors are important in the development of coronary artery disease (CAD) and heart attack, the susceptibility of humans to this fatal process is distinct from other animals. Mitochondrial dysfunction of cells in the arterial wall, particularly the endothelium, has been strongly implicated in the pathogenesis of CAD. In this manuscript, we review the established evidence and mechanisms in detail and explore the potential opportunities arising from analysing mitochondrial function in patient-derived cells such as endothelial colony-forming cells easily cultured from venous blood. We discuss how emerging technology and knowledge may allow us to measure mitochondrial dysfunction as a potential biomarker for diagnosis and risk management. We also discuss the "pros and cons" of animal models of atherosclerosis, and how patient-derived cell models may provide opportunities to develop novel therapies relevant for humans. Finally, we review several targets that potentially alleviate mitochondrial dysfunction working both via direct and indirect mechanisms and evaluate the effect of several classes of compounds in the cardiovascular context.

Disruption of Intracellular Calcium Homeostasis Leads to ERLIN2-Linked Hereditary Spastic Paraplegia in Patient-Derived Stem Cell Models

Hereditary spastic paraplegia (HSP) is a category of neurodegenerative illnesses with significant clinical and genetic heterogeneity. Homozygous truncated variants of the ERLIN2 gene lead to HSP18 (MIM #611225). However, it is still unclear whether there is an autosomal dominant pathogenic pattern. The specific molecular mechanism needs to be investigated. We generated patient-derived iPSC models to study the mechanism of ERLIN2 heterogeneous variants leading to HSP. We identified a heterozygous missense variant p.Val71Ala of ERLIN2 in an HSP family. Based on IP-mass spectrometry, we found that the ERLIN2 heterozygous missense variant protein recruited the ubiquitin E3 ligase RNF213 to degrade IP3R1. The degradation of IP3R1 leads to the reduction of intracellular free calcium, which triggered endoplasmic reticulum (ER) stress-mediated apoptosis. Calcium homeostasis imbalance inhibited the MAPK signaling pathway that contributed to decreased cell proliferation. In summary, these results suggest that the autosomal dominant inheritance of heterozygous missense variants in ERLIN2 is a novel pathogenic mode of HSP. Furthermore, the disruption of intracellular calcium homeostasis is the pathological mechanism.

HGG-08. COMBINATORIAL ACTIVITY OF CDK4/6-INHIBITORS AND TRAMETINIB IN PEDIATRIC HIGH-GRADE GLIOMA WITH BRAFV600E MUTATION AND HOMOZYGOUS CDKN2A DELETION

Abstract BRAFV600E mutations occur in 10-15% and homozygous CDKN2A deletions in approximately 40% of adolescent and pediatric high-grad glioma (HGG) and is associated with significantly decreased overall survival. Moreover, a subset of pHGG is defined by combined BRAFV600E mutation and concomitant CDKN2A homozygous deletion. Standard therapy has remained unchanged and consists of maximal safe resection and focal radiotherapy still resulting in poor overall survival. Therefore, new therapeutic approaches to increase patient survival are of utmost importance. Targeted therapy of BRAFV600E mutant HGG has emerged as effective treatment but remains challenging due to therapy resistance. CDK4/6 inhibitors represent a promising target in CDKN2A altered HGG. However, palbociclib demonstrated only low efficacy in HGG patients. Therefore, combination approaches may be more effective, and we investigated CDK4/6-inhibitors alone and in combination with trametinib in HGG cell models with BRAFV600E mutation and homozygous CDKN2A deletion. Efficacy of CDK4/6-inhibitor monotherapy and combinatorial approach with trametinib was assessed by short- and long-term viability assays in four patient-derived HGG cell models with homozygous CDKN2A deletion and BRAFV600E mutation. Furthermore, effects of CDK4/6 inhibitor therapy alone or in combination with trametinib on downstream signaling pathways (MAPK, PI3K) were analyzed with Western blots. Abemaciclib showed the highest activity in all cell models with IC50-values ranging from 0,5 – 2µM. Combined treatment approaches with trametinib showed synergistic effects across all cell models. Long-term viability assays revealed distinct sensitivity in the nanomolar range for CDK4/6-inhibitors and combined treatment with trametinib in all cell models. Exposure to abemaciclib and trametinib significantly decreased pRB, pERK, pS6, and pAKT protein expression levels when compared to monotherapy alone. Summarizing, combined treatment with CDK4/6-inhibitors and trametinib showed promising therapeutic effects on HGG models with homozygous CDKN2A deletion and BRAFV600E mutation. Currently, effects on cell cycle distribution and downstream molecular mechanisms are investigated to identify potential predictive biomarkers.

Q1291H-CFTR molecular dynamics simulations and ex vivo theratyping in nasal epithelial models and clinical response to elexacaftor/tezacaftor/ivacaftor in a Q1291H/F508del patient.

Background: Cystic fibrosis (CF) is caused by a wide spectrum of mutations in the CF transmembrane conductance regulator (CFTR) gene, with some leading to non-classical clinical presentations. We present an integrated in vivo, in silico and in vitro investigation of an individual with CF carrying the rare Q1291H-CFTR allele and the common F508del allele. At age 56years, the participant had obstructive lung disease and bronchiectasis, qualifying for Elexacaftor/Tezacaftor/Ivacaftor (ETI) CFTR modulator treatment due to their F508del allele. Q1291H CFTR incurs a splicing defect, producing both a normally spliced but mutant mRNA isoform and a misspliced isoform with a premature termination codon, causing nonsense mediated decay. The effectiveness of ETI in restoring Q1291H-CFTR is largely unknown. Methods: We collected clinical endpoint measurements, including forced expiratory volume in 1s percent predicted (FEV1pp) and body mass index (BMI), and examined medical history. In silico simulations of the Q1291H-CFTR were compared to Q1291R, G551D, and wild-type (WT)-CFTR. We quantified relative Q1291H CFTR mRNA isoform abundance in patient-derived nasal epithelial cells. Differentiated pseudostratified airway epithelial cell models at air liquid interface were created and ETI treatment impact on CFTR was assessed by electrophysiology assays and Western blot. Results: The participant ceased ETI treatment after 3months due to adverse events and no improvement in FEV1pp or BMI. In silico simulations of Q1291H-CFTR identified impairment of ATP binding similar to known gating mutants Q1291R and G551D-CFTR. Q1291H and F508del mRNA transcripts composed 32.91% and 67.09% of total mRNA respectively, indicating 50.94% of Q1291H mRNA was misspliced and degraded. Mature Q1291H-CFTR protein expression was reduced (3.18% ± 0.60% of WT/WT) and remained unchanged with ETI. Baseline CFTR activity was minimal (3.45 ± 0.25μA/cm2) and not enhanced with ETI (5.73 ± 0.48μA/cm2), aligning with the individual's clinical evaluation as a non-responder to ETI. Conclusion: The combination of in silico simulations and in vitro theratyping in patient-derived cell models can effectively assess CFTR modulator efficacy for individuals with non-classical CF manifestations or rare CFTR mutations, guiding personalized treatment strategies and optimizing clinical outcomes.

THU-271 - Immortalized patient-derived cell models for analysis of liver disease

THU-271 - Immortalized patient-derived cell models for analysis of liver disease

Hepatic Steatosis in Spinal Muscular Atrophy: Evidence for a Primary Hepatic Defect and Implications (S33.009)

<h3>Objective:</h3> To investigate evidence of hepatic steatosis in patients with spinal muscular atrophy (SMA) and SMA patient-derived induced pluripotent stem cell (iPSC) models of disease. <h3>Background:</h3> SMA is generally regarded as a motor neuron disease but increasing evidence of extra-neuronal manifestations suggest that these may become future co-morbidities when lifespan is prolonged. Hepatocellular microsteatosis has been noted in mouse models and pediatric autopsies, but it is unclear whether this is a primary defect from hepatocyte Survival Motor Neuron (SMN) deficiency or secondary to muscle denervation. <h3>Design/Methods:</h3> We retrospectively analyzed clinical data from a single center cohort of pediatric and adult SMA patients without liver disease who received hepatic sonography or fibroscan. Sonographic/fibroscan steatosis grade and serum markers of liver function were reviewed. In parallel, we differentiated Type 0–3 SMA patient iPSCs into hepatocytes (iHeps) and analyzed lipid accumulation and markers of hepatocyte function compared to wild-type (WT). We CRISPR edited a SMA Type 1 iPSC line to derive isogenic carrier (1 SMN1, 1 SMN2) and isogenic WT lines (2 SMN1) and analyzed the isolated effect of SMN deficiency on iHeps. <h3>Results:</h3> Mild to moderate hepatic steatosis was present in 100% SMA patients regardless of age and therapy. Raised hepatic enzymes were found in 33% SMA patients, but serum albumin, protein and INR were normal. Compared to WT, SMA iHeps displayed significantly more lipid accumulation which did not differ by SMA Type. Isolated SMN rescue on the same genetic background by CRISPR editing ameliorated lipid accumulation. <h3>Conclusions:</h3> To our knowledge, this is the first study to present evidence that hepatic steatosis may be a primary defect in all SMA types. Imaging evidence of hepatic steatosis may be frequent and could be used as a clinical biomarker. Establishing currently lacking screening and treatment guidelines for primary extra-neuronal defects in treated SMA patients is important. <b>Disclosure:</b> Dr. Yeo has nothing to disclose. Mr. Kiat has nothing to disclose. Mr. Ng has nothing to disclose. Prof. Ong has nothing to disclose. The institution of Dr. Darras has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Amicus. Dr. Darras has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Amicus. The institution of Dr. Darras has received research support from National Institutes of Health/National Institute of Neurological Disorders and Stroke,. The institution of Dr. Darras has received research support from Slaney Family Fund for SMA. The institution of Dr. Darras has received research support from Spinal Muscular Atrophy Foundation. The institution of Dr. Darras has received research support from CureSMA. The institution of Dr. Darras has received research support from Working on Walking Fund . The institution of Dr. Darras has received research support from CHERISH, CS2/CS12 . The institution of Dr. Darras has received research support from Biogen for CS11. The institution of Dr. Darras has received research support from AveXis. The institution of Dr. Darras has received research support from Sarepta Pharmaceuticals. The institution of Dr. Darras has received research support from PTC Therapeutics. The institution of Dr. Darras has received research support from Roche. The institution of Dr. Darras has received research support from Santhera. The institution of Dr. Darras has received research support from Scholar Rock. The institution of Dr. Darras has received research support from Fibrogen. The institution of Dr. Darras has received research support from Summit. Dr. Darras has received publishing royalties from a publication relating to health care. Dr. Darras has received publishing royalties from a publication relating to health care.

Abstract 1225: the existence, characteristics and underlying regulators of spontaneous epithelial-mesenchymal transition from a monophasic metaplastic squamous carcinoma patient-derived cancer cell model

Abstract Epithelial-mesenchymal transition (EMT) has been considered the mechanism underlying distant metastasis in epithelial cancers. The hallmarks of the EMT phenomenon are mainly the loss of cell-cell adhesion, acquisition of a mesenchymal phenotype, gain of mobility and invasiveness, and attainment of enhanced tumorigenicity and anchorage-independent growth. After EMT, cancer cells can enter and survive in fluid-filled spaces and subsequently colonize distant sites. Despite a huge body of in vitro and in vivo evidence recognizing EMT as an important event in tumor progression, whether EMT exists in naturally-occurring experimental settings remains a contentious debate in the field of pathology. Lack of convincing histopathological evidence of EMT in tumor subtypes without spindle sarcomatous tumor components and lack of dynamic change demonstration of EMT are to blame. In this report, we devised a naturally-occurring experimental setting to prove the existence of EMT in tumors completely lacking histological evidence of EMT. Further, we demonstrated dynamic change of EMT in in vitro and in vivo settings. We performed primary culture 37H from a monophasic metaplastic squamous cell carcinoma tissue (MMSCC), which exhibited no histologic features reminiscent of EMT, to examine whether EMT exists in tumors without sarcomatous histology. Two dominant subtypes demonstrating different morphology were derived from parental 37H: polygonal epithelial-type (HE) and epithelioid mesenchymal-type (HM) cells. The HE cells were E-cadherin+vimentin- predominant; while the HM cells were E-cadherin-vimentin+ predominant, and functionally concomitant with increased migration and invasion and anchorage-independent tumorigenicity. Taking advantage of the inherited differences between the HE and HM cells, we performed head-to-head comparison by RNA-seq and subsequently identified key EMT transcription factors (EMT-TFs) ZEB1 and ZEB2 in this naturally-occurring experimental setting. In the primary MMSCC tissue where 37H was derived, the upregulation of ZEB1 and ZEB2 was also observed in vimentin+ carcinoma cells. Further, the dynamic change of EMT was demonstrated in the HE and HM cells in in vitro and in vivo settings. Spontaneous EMT was observed specifically in the ZEB1-or ZEB2-overexpressed polygonal epithelial-type cells; the knockdown of ZEB1 and ZEB2 reverted EMT in the HM cells; and reverse EMT was found a requirement for HM cells to grow in a xenograft mouse model. In conclusion, this report backed up the existence of EMT in naturally-occurring tumor without histologic evidence of EMT. The identification of underlying regulators contributing to spontaneous EMT, and the demonstration of EMT dynamic change were also included. Citation Format: Huang-Chun Lien, Hui-Chieh Yu, Tom Wei-Wu Chen, I-Chun Chen, Chiao Lo, Ling-Chun Yeh, Li-Ping Hsiao, Yen-Shen Lu. the existence, characteristics and underlying regulators of spontaneous epithelial-mesenchymal transition from a monophasic metaplastic squamous carcinoma patient-derived cancer cell model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1225.

PD04-09 COMBINATION TREATMENT WITH HSP70/STUB1 MODULATOR AND ENZALUTAMIDE YIELDS SYNERGISTIC ACTIVITY IN ADVANCED PROSTATE CANCER

You have accessJournal of UrologyCME1 Apr 2023PD04-09 COMBINATION TREATMENT WITH HSP70/STUB1 MODULATOR AND ENZALUTAMIDE YIELDS SYNERGISTIC ACTIVITY IN ADVANCED PROSTATE CANCER Pengfei Xu, Joy C. Yang, Bo Chen, Christopher Nip, Shu Ning, Allen C. Gao, Hao Shao, Jason Gestwicki, Christopher P. Evans, and Chengfei Liu Pengfei XuPengfei Xu More articles by this author , Joy C. YangJoy C. Yang More articles by this author , Bo ChenBo Chen More articles by this author , Christopher NipChristopher Nip More articles by this author , Shu NingShu Ning More articles by this author , Allen C. GaoAllen C. Gao More articles by this author , Hao ShaoHao Shao More articles by this author , Jason GestwickiJason Gestwicki More articles by this author , Christopher P. EvansChristopher P. Evans More articles by this author , and Chengfei LiuChengfei Liu More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003228.09AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Ubiquitin proteasome system is suppressed in enzalutamide resistant prostate cancer cells and that the HSP70/STUB1 machinery is involved in androgen receptor (AR) and AR variant protein stabilization. Targeting HSP70 could be a valuable strategy to overcome the resistance of androgen receptor signaling inhibitors (ARSI) in advanced prostate cancer. In this study, we tested novel HSP70/STUB1modulators in enzalutamide resistant cells and patient-derived prostate cancer cell models. METHODS: Expression of AR-V7, HSP70 and STUB1 were determined by qRT-PCR and western blot. Expression of HSP70 and STUB1 was down-regulated using specific siRNA. HSP70/STUB1 and AR-V7 interaction was determined by co-immunoprecipitation and dual immunofluorescence. Tumor organoids were established from the patient derived xenografts (PDX) and the viability was stained by LIVE/DEAD™ Cell Imaging Kit. The effects of HSP70 inhibitors on enzalutamide sensitivity were examined in cell line model and patient-derived cell models. RESULTS: A novel HSP70 inhibitor JG98 significantly suppressed drug resistant C4-2B MDVR and CWR22Rv1 cell growth and enhanced enzalutamide treatment (p<0.001). JG98 also suppressed the PDX derived organoid growth and induced organoid death in a dose dependent manner (p<0.001). Mechanistically, JG98 suppressed AR/AR-V7 expression in resistant cells and promoted STUB1 entering into the nucleus and bound to AR-V7. Knockdown of STUB1 diminished the anti-cancer effect and AR-V7 inhibition by JG98. A more potent HSP70 inhibitor JG231 was developed from JG98. JG231 significantly improved the drug solubility and showed better pharmacokinetic characteristics than JG98. Moreover, JG231 effectively suppressed the cell growth and enhanced enzalutamide treatment in resistant cells and PDX derived prostate cancer cells (p<0.001). CONCLUSIONS: The HSP70/STUB1 machinery involved in AR/AR-V7 regulation and enzalutamide resistance. Targeting HSP70 by novel HSP70/STUB1 modulators overcome the ARSI resistance and improve their therapy. Source of Funding: This work was supported in part by grants NIH/NCI R37CA249108 (C, Liu) and R01CA251253 (C, Liu) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e145 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Pengfei Xu More articles by this author Joy C. Yang More articles by this author Bo Chen More articles by this author Christopher Nip More articles by this author Shu Ning More articles by this author Allen C. Gao More articles by this author Hao Shao More articles by this author Jason Gestwicki More articles by this author Christopher P. Evans More articles by this author Chengfei Liu More articles by this author Expand All Advertisement PDF downloadLoading ...

Novel therapeutic approaches for pleural mesothelioma identified by functional ex vivo drug sensitivity testing

ObjectivesPleural mesothelioma (PM) is an aggressive malignancy with limited treatment options. The first-line therapy has remained unchanged for two decades and consists of pemetrexed in combination with cisplatin. Immune-checkpoint inhibitors (nivolumab plus ipilimumab) have high response rates, resulting in recent updates in treatment recommendations by the U.S. Food and Drug Administration. However, the overall benefits of combination treatment are modest, suggesting that other targeted therapy options should be investigated. Materials and MethodsWe employed high-throughput drug sensitivity and resistance testing on five established PM cell lines using 527 cancer drugs in a 2D setting. Drugs of the greatest potential (n = 19) were selected for further testing in primary cell models derived from pleural effusions of seven PM patients. ResultsAll established and primary patient-derived PM cell models were sensitive to the mTOR inhibitor AZD8055. Furthermore, another mTOR inhibitor (temsirolimus) showed efficacy in most of the primary patient-derived cells, although a less robust effect was observed when compared with the established cell lines. Most of the established cell lines and all patient-derived primary cells exhibited sensitivity to the PI3K/mTOR/DNA-PK inhibitor LY3023414. The Chk1 inhibitor prexasertib showed activity in 4/5 (80%) of the established cell lines and in 2/7 (29%) of the patient-derived primary cell lines. The BET family inhibitor JQ1 showed activity in four patient-derived cell models and in one established cell line. ConclusionmTOR and Chk1 pathways had promising results with established mesothelioma cell lines in an ex vivo setting. In patient-derived primary cells, drugs targeting mTOR pathway in particular showed efficacy. These findings may inform novel treatment strategies for PM.

3D in vitro modelling of human patient microglia: A focus on clinical translation and drug development in neurodegenerative diseases

Microglia have an increasingly well-recognised role in the pathogenesis of neurodegenerative diseases, thereby becoming attractive therapeutic targets. However, the development of microglia-targeted therapeutics for neurodegeneration has had limited success. This stems partly from the lack of clinically relevant microglia model systems. To circumvent this translational gap, patient-derived microglial cell models established using conventional 2D in vitro techniques have emerged. Though promising, these models lack the microenvironment and multicellular interactions of the brain needed to maintain microglial homeostasis. In this review, we discuss the use of 3D in vitro platforms to improve microglia modelling and their potential benefits to fast-track drug development for neurodegenerative diseases.

Addressing Modern Diagnostic Pathology for Patient-Derived Soft Tissue Sarcosphere Models in the Era of Functional Precision Oncology

Responses to therapy often cannot be exclusively predicted by molecular markers, thus evidencing a critical need to develop tools for better patient selection based on relations between tumor phenotype and genotype. Patient-derived cell models could help to better refine patient stratification procedures and lead to improved clinical management. So far, such ex vivo cell models have been used for addressing basic research questions and in preclinical studies. As they now enter the era of functional precision oncology, it is of utmost importance that they meet quality standards to fully represent the molecular and phenotypical architecture of patients’ tumors. Well-characterized ex vivo models are imperative for rare cancer types with high patient heterogeneity and unknown driver mutations. Soft tissue sarcomas account for a very rare, heterogeneous group of malignancies that are challenging from a diagnostic standpoint and difficult to treat in a metastatic setting because of chemotherapy resistance and a lack of targeted treatment options. Functional drug screening in patient-derived cancer cell models is a more recent approach for discovering novel therapeutic candidate drugs. However, because of the rarity and heterogeneity of soft tissue sarcomas, the number of well-established and characterized sarcoma cell models is extremely limited. Within our hospital-based platform we establish high-fidelity patient-derived ex vivo cancer models from solid tumors for enabling functional precision oncology and addressing research questions to overcome this problem. We here present 5 novel, well-characterized, complex-karyotype ex vivo soft tissue sarcosphere models, which are effective tools to study molecular pathogenesis and identify the novel drug sensitivities of these genetically complex diseases. We addressed the quality standards that should be generally considered for the characterization of such ex vivo models. More broadly, we suggest a scalable platform to provide high-fidelity ex vivo models to the scientific community and enable functional precision oncology.