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Schleiermacher, G.

Publications and source records attributed to Schleiermacher, G..

7 recordsLinked to original sources

Sensitivity profiling reveals consistent drug responses across preclinical neuroblastoma models

Despite intensive treatment, overall survival for high-risk and relapse neuroblastoma patients remains below 50%. Even though comprehensive molecular profiling enables treatment stratification, druggable alterations have been identified for only a subset of patients. In vitro drug screening offers a complementary approach. Here, we compare the translational potential of three preclinical drug screening methods: ex vivo short-term, in vitro patient-derived organoid and in vivo patient-derived xenograft (PDX) drug testing. In total, 55 screens were performed from 38 neuroblastoma samples and five pediatric non-malignant samples, testing 77-224 drugs per screen. Ex vivo short-term drug screens achieved higher success rates than organoid screens (65% versus 23%) and shorter turnaround times (14 days versus 3-12 months). Matched samples showed consistent drug sensitivities across sample origin (patient versus PDX-derived; mean r = 0.84) and method (ex vivo short-term versus organoids; mean r = 0.87), demonstrating that ex vivo short-term screens recapitulate drug sensitivities found in long-term organoid models. In parallel, as part of the ITCC-P4 consortium, ten compounds were tested in vivo in eight PDX models, with samples matching the ex vivo screens. For seven out of ten clinically available compounds, ex vivo drug responses were comparable with in vivo responses in matched PDX models. These results demonstrate that, while organoids and PDX models remain essential for drug discovery, ex vivo short-term drug screening provides a rapid alternative for functional precision oncology in neuroblastoma.

cell biology↗

KDM5-driven transcriptional noise fuels plasticity-led awakening and relapse in paediatric cancer

How drug-tolerant persister (DTP) cells escape quiescence to drive tumour relapse is a central unresolved question in cancer evolution. Here, we identify transcriptional noise (TN), defined as the stochastic variability in gene expression, as a latent property of paediatric cancer cells that becomes a driver of adaptive regrowth after treatment withdrawal. Using functional assays, lineage tracing, single-cell transcriptomics, and multiscale landscape modelling, we show that therapy enriches mesenchymal-like tolerant states in neuroblastoma without clonal selection, while post-treatment awakening is a stochastic process fuelled by noise-enabled plasticity in cell-identity programmes. The histone demethylase KDM5A relocates to noisy cell-state genes during awakening, promoting H3K4me3 removal and chromatin remodelling at these loci. KDM5 inhibition abrogates this process, and suppresses transcriptional noise, halts DTP exit, and prevents tumour recovery in both neuroblastoma and hepatoblastoma models. These results establish DTP as an exploitable evolutionary bottleneck, positioning KDM5-mediated transcriptional noise as an actionable therapeutic target to limit cancer adaptation and relapse GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/682004v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@edba70org.highwire.dtl.DTLVardef@16b1bd9org.highwire.dtl.DTLVardef@f153acorg.highwire.dtl.DTLVardef@1ac5a4e_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

Differential chromatin response to retinoic acid in neuroblastoma according to type of ATRX mutation

Neuroblastoma is a childhood cancer, arising in the developing sympathetic nervous system. Differentiation therapy with 13-cis-retinoic acid (RA) is routinely given to children with high-risk neuroblastoma in the minimal residual disease setting to prevent relapse, however there is little understanding of which patients benefit from RA therapy. ATRX alterations are identified in 10% of high-risk neuroblastomas and associated with poor outcomes. The commonest type of ATRX alterations in neuroblastoma are in-frame multi-exon deletions, followed by nonsense mutations predicted to result in loss-of-function (ATRX LoF). We treated paired ATRX wild-type and ATRX LoF neuroblastoma cell lines with RA and show that cells with ATRX LoF fail to upregulate direct RA target genes. Cells with ATRX LoF also show reduced chromatin accessibility at genes involved in differentiation and development following RA treatment. Conversely, neuroblastoma models with in-frame deletions mount a response to RA and show in-vitro sensitivity to RA. Taken together this shows that the mechanism of differentiation in ATRX-altered neuroblastoma depends on the type of ATRX alteration, with implications relating to both oncogenesis and therapeutic response.

cancer biology↗

COMBINATION THERAPIES TARGETING ALK-ABERRANT NEUROBLASTOMA IN PRECLINICAL MODELS.

BackgroundALK activating mutations are identified in approximately 10% of newly diagnosed neuroblastomas and ALK amplifications in a further 1-2% of cases. Lorlatinib, a third generation ALK inhibitor, will soon be given alongside induction chemotherapy for children with ALK-aberrant neuroblastoma. However, resistance to single agent treatment has been reported and therapies that improve the response duration are urgently required. We studied the preclinical combination of lorlatinib with chemotherapy, or with the MDM2 inhibitor, idasanutlin, as recent data has suggested that ALK inhibitor resistance can be overcome through activation of the p53-MDM2 pathway. AimsTo study the preclinical activity of ALK inhibitors alone and in combination with chemotherapy or idasanutlin. MethodsWe compared different ALK inhibitors in preclinical models prior to evaluating lorlatinib in combination with chemotherapy or idasanutlin. We developed a triple chemotherapy (CAV: cyclophosphamide, doxorubicin and vincristine) in vivo dosing schedule and applied this to both neuroblastoma genetically engineered mouse models (GEMM) and patient derived xenografts (PDX). ResultsLorlatinib in combination with chemotherapy was synergistic in immunocompetent neuroblastoma GEMM. Significant growth inhibition in response to lorlatinib was only observed in the ALK-amplified PDX model with the highest ALK expression. In this PDX lorlatinib combined with idasanutlin resulted in complete tumor regression and significantly delayed tumor regrowth. ConclusionOur study suggests that in neuroblastoma, high ALK expression could be associated with response to lorlatinib and either chemotherapy or idasanutlin. The synergy between MDM2 inhibition and ALK inhibition warrants further evaluation of this combination as a potential clinical approach for children with neuroblastoma. STATEMENT OF TRANSLATIONAL RELEVANCENeuroblastoma is a pediatric tumor of the developing sympathetic nervous system. Around 50% of high-risk neuroblastoma patients are curable. Mutations or amplification of Anaplastic Lymphoma Kinase (ALK) have emerged as a marker with which to further risk-stratify patients. The ALK inhibitor lorlatinib will soon be used alongside chemotherapy in upfront treatment of high-risk patients with ALK-aberrant disease. In this preclinical study, we used a panel of ALK aberrant neuroblastoma models to evaluate ALK inhibitors focusing on lorlatinib in combination with conventional chemotherapy and the small molecule MDM2 inhibitor idasanutlin. In both approaches we found synergy in models with high basal ALK expression without MAPK pathway alterations. We conclude that in neuroblastoma the level of ALK expression could be an additional biomarker predictive of clinical response to ALK inhibitors.

cancer biology↗

Interplay between intrinsic reprogramming potential and microenvironment controls neuroblastoma cell plasticity and identity

Two cell identities, noradrenergic and mesenchymal, have been characterized in neuroblastoma cell lines according to their epigenetic landscapes relying on specific circuitries of transcription factors. Yet, their relationship and relative contribution in patient tumors remain poorly defined. Here, we demonstrate that the knock-out of GATA3, but not of PHOX2A or PHOX2B, in noradrenergic cells induces a mesenchymal phenotype. Our results document spontaneous plasticity in several models between both identities and show that plasticity relies on epigenetic reprogramming. We demonstrate that an in vivo microenvironment provides a powerful pressure towards a noradrenergic identity for these models. Consistently, tumor cells with a mesenchymal identity are not detected in a series of PDX models. Further study of the intra-tumor noradrenergic heterogeneity reveals two distinct cell populations exhibiting features of chromaffin-like or sympathoblast-like cells. This work emphasizes that both external cues of the environment and intrinsic factors control plasticity and cell identity in neuroblastoma.

cancer biology↗

Minimally invasive classification of pediatric solid tumors using reduced representation bisulfite sequencing of cell-free DNA: a proof-of-principle study

In the clinical management of pediatric solid tumors, histological examination of tumor tissue obtained by a biopsy remains the gold standard to establish a conclusive pathological diagnosis. The DNA methylation pattern of a tumor is known to correlate with the histopathological diagnosis across cancer types and is showing promise in the diagnostic workup of tumor samples. This methylation pattern can be detected in the cell-free DNA. Here, we provide proof-of-concept of histopathologic classification of pediatric tumors using cell-free reduced representation bisulfite sequencing (cf-RRBS) from retrospectively collected plasma and cerebrospinal fluid samples. We determined the correct tumor type in 49 out of 60 (81.6%) samples starting from minute amounts (less than 10 ng) of cell-free DNA. We demonstrate that the majority of misclassifications were associated with sample quality and not with the extent of disease. Our approach has the potential to help tackle some of the remaining diagnostic challenges in pediatric oncology in a cost-effective and minimally invasive manner. Translational relevanceObtaining a correct diagnosis in pediatric oncology can be challenging in some tumor types, especially in renal tumors or central nervous system tumors. Furthermore, the diagnostic odyssey can result in anxiety and discomfort for these children. By applying a novel technique, reduced representation bisulfite sequencing on cell-free DNA (cf-RRBS), we show the feasibility of obtaining the histopathological diagnosis with a minimally invasive test on either plasma or cerebrospinal fluid. Furthermore, we were able to derive the copy number profile or tumor subtype from the same assay. Given that primary tumor material might be difficult to obtain, in particular in critically ill children or depending on the tumor location, and might be limited in terms of quantity or quality, our assay could become complementary to the classical tissue biopsy in difficult cases.

genomics↗

Circulating microRNA biomarkers for metastatic disease in neuroblastoma patients

In this study, the circulating miRNome from diagnostic neuroblastoma serum was assessed for identification of non-invasive biomarkers with potential in monitoring metastatic disease. After determining the circulating neuroblastoma miRNome, 743 miRNAs were screened in two independent cohorts of 131 and 54 patients. Evaluation of serum miRNA variance in a model testing for tumor stage, MYCN status, age at diagnosis and overall survival, revealed tumor stage as the most significant factor impacting miRNA abundance in neuroblastoma serum. Differential expression analysis between patients with metastatic and localized disease revealed 9 miRNAs strongly associated with metastatic stage 4 disease in both patient cohorts. Increasing levels of these miRNAs were also observed in serum from xenografted mice bearing human neuroblastoma tumors. Moreover, murine serum miRNA levels were strongly associated with tumor volume, suggesting this miRNA signature may be applied to monitor disease burden.

cancer biology↗