Publications by authors named "Kristian Pajtler"

Recent genomic studies have allowed the subdivision of intracranial ependymomas into molecularly distinct groups with highly specific clinical features and outcomes. The majority of supratentorial ependymomas (ST-EPN) harbor ZFTA-RELA fusions which were designated, in general, as an intermediate risk tumor variant. However, molecular prognosticators within ST-EPN ZFTA-RELA have not been determined yet.

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Background: Ependymomas of the spinal cord are rare among children and adolescents, and the individual risk of disease progression is difficult to predict. This study aims to evaluate the prognostic impact of molecular typing on pediatric spinal cord ependymomas.

Methods: Eighty-three patients with spinal ependymomas ≤22 years registered in the HIT-MED database (German brain tumor registry for children, adolescents, and adults with medulloblastoma, ependymoma, pineoblastoma, and CNS-primitive neuroectodermal tumors) between 1992 and 2022 were included.

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Article Synopsis
  • - Chromothripsis is a process where a single catastrophic event causes significant genomic rearrangements, but its variability across different tumor clones and response to treatments is not well understood.
  • - This study investigates chromothripsis in p53-deficient medulloblastoma and neural stem cells, focusing on the genomic and transcriptomic changes involved.
  • - The researchers analyze the order of genetic events, explore subclonal variation, and identify how chromothripsis influences cancer development, targeted therapies, and the fitness of neural progenitor cells.
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Wilms tumors are commonly associated with predisposition syndromes. Many of these syndromes are associated with specific phenotypic features and are discussed in the related article from the AACR Pediatric Cancer Working Group. Guidelines for surveillance in this population were published in 2017, but since then several studies have identified new genes with recurrent pathogenic variants associated with increased risk for Wilms tumor development.

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Adolescents and young adults (AYAs; ages 15-39 years) are a vulnerable population facing challenges in oncological care, including access to specialized care, transition of care, unique tumor biology, and poor representation in clinical trials. Brain tumors are the second most common tumor type in AYA, with malignant brain tumors being the most common cause of cancer-related death. The 2021 WHO Classification for central nervous system (CNS) Tumors highlights the importance of integrated molecular characterization with histologic diagnosis in several tumors relevant to the AYA population.

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Article Synopsis
  • - Wilms tumors are linked to various predisposition syndromes, many of which involve overgrowth and an increased risk for other cancers like hepatoblastoma.
  • - In 2017, surveillance guidelines for patients at risk for Wilms tumors were established, and the AACR Pediatric Cancer Working Group recently updated these guidelines based on new research and risk data.
  • - The update aims to inform healthcare professionals—including pediatric oncologists and geneticists—about revised diagnostic criteria and to standardize surveillance recommendations in North America and Australia for patients with relevant syndromes.
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Background: Ependymoma (EPN) is not a uniform disease but represents different disease types with biological and clinical heterogeneity. However, the pattern of when and where different types of EPN relapse is not yet comprehensively described.

Methods: We assembled 269 relapsed intracranial EPN from pediatric (n=233) and adult (n=36) patients from European and Northern American cohorts and correlated DNA methylation patterns and copy-number alterations with clinical information.

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Background: Radiotherapy (RT) involving craniospinal irradiation (CSI) is important in the initial treatment of medulloblastoma. At recurrence, the re-irradiation options are limited and associated with severe side-effects.

Methods: For pre-irradiated patients, patients with re-irradiation (RT2) were matched by sex, histology, time to recurrence, disease status and treatment at recurrence to patients without RT2.

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Genetic predisposition to neuroblastoma (NB) is relatively rare. Only 1% to 2% of patients have a family history of NB, 3% to 4% of cases present with bilateral or multifocal primary tumors, and occasional patients have syndromes that are associated with increased NB risk. Previously, a germline pathogenic variant (GPV) in PHOX2B was associated with Hirschsprung disease and congenital central hypoventilation syndrome.

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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
  • * Many children with brain tumors display features of specific syndromes or have a family history of cancer, highlighting a potential genetic link to their tumors.
  • * Advances in molecular research have improved our understanding of CNS tumors, leading to better identification of germline predispositions, which can guide family testing and tumor management.
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Purpose: Primary central nervous system (CNS) gliomas can be classified by characteristic genetic alterations. In addition to solid tissue obtained via surgery or biopsy, cell-free DNA (cfDNA) from cerebrospinal fluid (CSF) is an alternative source of material for genomic analyses.

Experimental Design: We performed targeted next-generation sequencing of CSF cfDNA in a representative cohort of 85 patients presenting at two neurooncological centers with suspicion of primary or recurrent glioma.

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Posterior fossa type A (PF-EPN-A, PFA) ependymoma are aggressive tumors that mainly affect children and have a poor prognosis. Histopathology shows significant intratumoral heterogeneity, ranging from loose tissue to often sharply demarcated, extremely cell-dense tumor areas. To determine molecular differences in morphologically different areas and to understand their clinical significance, we analyzed 113 PF-EPN-A samples, including 40 corresponding relapse samples.

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The diagnosis of ependymoma has moved from a purely histopathological review with limited prognostic value to an integrated diagnosis, relying heavily on molecular information. However, as the integrated approach is still novel and some molecular ependymoma subtypes are quite rare, few studies have correlated integrated pathology and clinical outcome, often focusing on small series of single molecular types. We collected data from 2023 ependymomas as classified by DNA methylation profiling, consisting of 1736 previously published and 287 unpublished methylation profiles.

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Many genes that drive normal cellular development also contribute to oncogenesis. Medulloblastoma (MB) tumors likely arise from neuronal progenitors in the cerebellum, and we hypothesized that the heterogeneity observed in MBs with sonic hedgehog (SHH) activation could be due to differences in developmental pathways. To investigate this question, here we perform single-nucleus RNA sequencing on highly differentiated SHH MBs with extensively nodular histology and observed malignant cells resembling each stage of canonical granule neuron development.

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Medulloblastomas with extensive nodularity are cerebellar tumors characterized by two distinct compartments and variable disease progression. The mechanisms governing the balance between proliferation and differentiation in MBEN remain poorly understood. Here, we employ a multi-modal single cell transcriptome analysis to dissect this process.

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Lynch syndrome (LS) predisposes to cancer in adulthood and is caused by heterozygous germline variants in a mismatch repair (MMR) gene. Recent studies show an increased prevalence of LS among children with cancer, suggesting a causal relationship. For LS-spectrum (LSS) cancers, including high-grade gliomas and colorectal cancer, causality has been supported by typical MMR-related tumor characteristics, but for non-LSS cancers, causality is unclear.

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Article Synopsis
  • The study focuses on the progression of low-grade diffuse astrocytomas into grade 4 tumors and its impact on patient outcomes, highlighting the need for better understanding to enhance patient care.
  • Researchers analyzed genetic data from a cohort of patients with IDH-mutant astrocytomas, revealing significant alterations like increased chromosomal rearrangements and inactivation of key genes related to cell cycle regulation after treatment.
  • Results indicate that combined postoperative radiation and chemotherapy, especially temozolomide, may lead to improved survival outcomes, particularly in patients with grade 3 tumors, suggesting a need for more effective treatment strategies.
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Background: Parameningeal location of rhabdomyosarcoma (PM RMS) is known to be an unfavorable prognostic factor. Scarce data are available on radiotherapy (RT) concepts with regard to outcome.

Methods: Treatment and outcome of 395 children with PM RMS registered within two Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry (1995-2021) were evaluated.

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Purpose: Inflammatory myofibroblastic tumors (IMTs) are often driven by anaplastic lymphoma kinase fusions and less frequently by alternative fusions such as . We describe the clinical characteristics, treatment approach, and outcome for a series of young patients with IMTs and alterations.

Methods: This was a retrospective, international, multicenter study analyzing young patients (younger than 21 years) with -altered IMTs treated in 10 European referral centers between 2014 and 2022.

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Background: Outcome of primary metastatic rhabdomyosarcoma (RMS) is poor. Certain risk factors as fusion status, Oberlin score, and local treatment of primary tumor are known to influence prognosis.

Procedure: Patients with metastatic RMS were treated according to Cooperative Weichteilsarkom Studiengruppe (CWS) guidance with chemotherapy (CHT), radiotherapy (RT) excluding total lung irradiation (TLI), complete resection of the primary tumor, and metastasectomy if possible.

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Article Synopsis
  • - This study focuses on identifying the cellular origins of common childhood brain tumors (ependymoma, pilocytic astrocytoma, and medulloblastoma) using a human cerebellar atlas, which offers a more accurate reference than previous methods that compared human tumors to mouse tissues.
  • - Using a large dataset of normal and tumor-specific gene expressions, the researchers suggest that different brain tumors can arise from various progenitor cells in the cerebellum and have distinct lineage origins.
  • - The findings indicate that tumors may consist of cells resembling different types from a specific developmental lineage, highlighting the complexity of tumor origins and suggesting potential therapeutic strategies based on identified tumor-specific genes.
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Novel drug treatments for pediatric patients with cancer are urgently needed. Success of drug development in pediatric oncology has been promising, but many drugs still fail in translation from preclinical to clinical phases. To increase the translational potential, several improvements have been implemented, including the use of clinically achievable concentrations in the drug testing phase.

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Background: The prognosis for Li-Fraumeni syndrome (LFS) patients with medulloblastoma (MB) is poor. Comprehensive clinical data for this patient group is lacking, challenging the development of novel therapeutic strategies. Here, we present clinical and molecular data on a retrospective cohort of pediatric LFS MB patients.

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