Publications by authors named "Olaf Witt"

Introduction: Despite druggable events to be present in 80 % of neuroblastomapatients within the Princess Máxima Center precision medicine program 'iTHER', clinical uptake of treatment recommendations has been low, and the clinical impact for individual patients remains hard to predict. This stresses the need for a method integrating genomics and transcriptomics with functional approaches into therapeutic decision making.

Methods: We aimed to launch an online repository integrating genomics and transcriptomics with high-throughput drug screening (HTS) of nineteen commonly used neuroblastoma cell lines and fifteen neuroblastoma patient-derived organoids (NBL-PDOs).

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Background: High-grade glioma (HGG) of the spinal cord constitutes rare tumors in the pediatric population. Knowledge of the molecular profile of this pediatric HGG (pedHGG) subgroup is limited and the clinical outcome is poor. Therefore, the aim of this study is to provide more profound investigations of molecular characteristics and clinical features of these tumors.

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Background: Due to their anatomical locations, optic pathway gliomas (OPGs) can rarely be cured by resection. Given the importance of preserving visual function, we analyzed radiological and visual acuity (VA) outcomes for the type II RAF inhibitor tovorafenib in the OPG subgroup of the phase 2 FIREFLY-1 trial.

Methods: FIREFLY-1 investigated the efficacy (arm 1, n=77), safety, and tolerability (arms 1/2) of tovorafenib (420 mg/m2 once weekly; 600 mg maximum) in patients with BRAF-altered relapsed/refractory pediatric low-grade glioma (pLGG).

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Aims: DNA methylation profiling, recently endorsed by the World Health Organisation (WHO) as a pivotal diagnostic tool for brain tumours, most commonly relies on bead arrays. Despite its widespread use, limited data exist on the technical reproducibility and potential cross-institutional differences. The LOGGIC Core BioClinical Data Bank registry conducted a prospective laboratory comparison trial with 12 international laboratories to enhance diagnostic accuracy for paediatric low-grade gliomas, focusing on technical aspects of DNA methylation data generation and profile interpretation under clinical real-time conditions.

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Our international team highlights issues with efficacy reports in several studies on DMG with the new drug ONC201.

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Background: Certain paediatric nervous system malignancies have dismal prognoses. Retinoic acid (RA) is used in neuroblastoma treatment, and preclinical data indicate potential benefit in selected paediatric brain tumour entities. However, limited single-agent efficacy necessitates combination treatment approaches.

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Introduction: Neurosurgery is considered the mainstay of treatment for pediatric low-grade glioma (LGG); the extent of resection determines subsequent stratification in current treatment protocols. Yet, surgical radicality must be balanced against the risks of complications that may affect long-term quality of life. We investigated whether this consideration impacted surgical resection patterns over time for patients of the German LGG studies.

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Within the past decade, incremental integration of molecular characteristics into the classification of central nervous system neoplasms increasingly facilitated precise diagnosis and advanced stratification, beyond potentially providing the foundation for advanced targeted therapies. We report a series of three cases of infant-type hemispheric glioma (IHG) involving three infants diagnosed with neuroepithelial tumors of the cerebral hemispheres harboring a novel, recurrent TRIM24::MET fusion. Histopathology showed glial tumors with either low-grade or high-grade characteristics, while molecular characterization found an additional homozygous CDKN2A/B deletion in two cases.

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Pediatric low-grade glioma (pLGG) is the most common childhood brain tumor group. The natural history, when curative resection is not possible, is one of a chronic disease with periods of tumor stability and episodes of tumor progression. While there is a high overall survival rate, many patients experience significant and potentially lifelong morbidities.

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Introduction: Patients with pediatric low-grade gliomas (pLGGs), the most common primary brain tumors in children, can often benefit from MAPK inhibitor (MAPKi) treatment. However, rapid tumor regrowth, also referred to as rebound growth, may occur once treatment is stopped, constituting a significant clinical challenge.

Methods: Four patient-derived pediatric glioma models were investigated to model rebound growth in vitro based on viable cell counts in response to MAPKi treatment and withdrawal.

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Article Synopsis
  • Pediatric low-grade glioma (pLGG) is mainly caused by genomic changes in the MAPK pathway, particularly KIAA1549::BRAF fusions and BRAF V600E mutations, making it suitable for targeted therapies like tovorafenib instead of traditional treatments.
  • The combination of dabrafenib and trametinib is FDA-approved for BRAF V600E-pLGG but not effective for tumors with BRAF fusions, as it may worsen tumor growth.
  • The LOGGIC/FIREFLY-2 trial is assessing tovorafenib against standard chemotherapy in patients under 25 with pLGG and BRAF mutations, focusing on overall response rate and safety.
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Purpose: Patients with MYC-amplified Group 3 medulloblastoma (MB) (subtype II) show poor progression-free survival rates. Class I histone deacetylase inhibitors (HDACi) are highly effective for the treatment of MYC-amplified MB in vitro and in vivo. Drug combination regimens including class I HDACi may represent an urgently needed novel treatment approach for this high risk disease.

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Within the last few decades, we have witnessed tremendous advancements in the study of pediatric low-grade gliomas (pLGG), leading to a much-improved understanding of their molecular underpinnings. Consequently, we have achieved successful milestones in developing and implementing targeted therapeutic agents for treating these tumors. However, the community continues to face many unknowns when it comes to the most effective clinical implementation of these novel targeted inhibitors or combinations thereof.

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Purpose: Although pediatric low-grade gliomas (pLGG) are the most common pediatric brain tumors, patient-derived cell lines reflecting pLGG biology in culture are scarce. This also applies to the most common pLGG subtype pilocytic astrocytoma (PA). Conventional cell culture approaches adapted from higher-grade tumors fail in PA due to oncogene-induced senescence (OIS) driving tumor cells into arrest.

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Article Synopsis
  • The trial demonstrated an overall response rate of 67% and a median duration of response of 16.6 months based on RANO-HGG criteria, while the RAPNO criteria showed an overall response rate of 51% and median duration of response of 13.8 months.
  • Common treatment-related side effects included hair color changes (76%), elevated creatine phosphokinase
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Article Synopsis
  • * pLGG is viewed as a chronic condition, emphasizing the significance of quality of life and functional outcomes, along with advancements in understanding its biological mechanisms for developing targeted therapies.
  • * The International Pediatric Low-Grade Glioma Coalition (iPLGGc) reviews the latest information on pLGG, including its epidemiology, treatment options, and ongoing challenges, while introducing additional research papers on preclinical models, clinical trial frameworks, and tumor resistance issues.
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Purpose: MYC-driven Group 3 medulloblastoma (MB) (subtype II) is a highly aggressive childhood brain tumor. Sensitivity of MYC-driven MB to class I histone deacetylase inhibitors (HDACi) has been previously demonstrated in vitro and in vivo. In this study we characterize the transcriptional effects of class I HDACi in MYC-driven MB and explore beneficial drug combinations.

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Pediatric low-grade gliomas (pLGGs) are the most common brain tumor in young children. While they are typically associated with good overall survival, children with these central nervous system tumors often experience chronic tumor- and therapy-related morbidities. Moreover, individuals with unresectable tumors frequently have multiple recurrences and persistent neurological symptoms.

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Background: Detection of the V600E mutation in pediatric low-grade glioma has been associated with a lower response to standard chemotherapy. In previous trials, dabrafenib (both as monotherapy and in combination with trametinib) has shown efficacy in recurrent pediatric low-grade glioma with V600 mutations, findings that warrant further evaluation of this combination as first-line therapy.

Methods: In this phase 2 trial, patients with pediatric low-grade glioma with V600 mutations who were scheduled to receive first-line therapy were randomly assigned in a 2:1 ratio to receive dabrafenib plus trametinib or standard chemotherapy (carboplatin plus vincristine).

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Article Synopsis
  • The study focuses on the effectiveness of the combination of dabrafenib and trametinib for treating pediatric high-grade gliomas (pHGG) with the V600 mutation, which is found in 5%-10% of such cases and has limited treatment options.
  • It was a phase II trial involving 41 pediatric patients, and results showed a 56% overall response rate (ORR), with a median duration of response of 22.2 months and a median overall survival of 32.8 months.
  • The findings indicate that this treatment combination may offer better outcomes compared to traditional chemotherapy, representing a potential targeted therapy for affected children and adolescents with relapsed or refractory V600-mutant HGG.*
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Background: FGFR alterations are reported across various malignancies and might act as oncogenic drivers in multiple histologies. Erdafitinib is an oral, selective pan-FGFR tyrosine kinase inhibitor with activity in FGFR-altered advanced urothelial carcinoma. We aimed to evaluate the safety and activity of erdafitinib in previously treated patients with FGFR-altered advanced solid tumours.

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