👤 Wilhelm G Dirks

Pediatric Low-Grade Glioma (pLGG) is the most common pediatric brain tumor, and radiomics-based machine learning (ML) models have shown promise in identifying BRAF fusion and BRAF p.V600E mutation. This bicentric retrospective study included 495 children diagnosed between 1999 and 2023. The local hospital dataset comprised Magnetic Resonance Imaging (MRI) scans of patients with BRAF fusion (n = 190), BRAF p.V600E mutation (n = 95), FGFR1 (n = 25), and other molecular subtypes (n = 144), while an external dataset included BRAF fusion (n = 32) and BRAF p.V600E mutation (n = 9) cases. Radiomics features were extracted from Fluid-Attenuated Inversion Recovery images, and Random Forest classifiers were trained using Monte Carlo data splits and leave-one-out validation. The best-performing model achieved an average one-vs-the-rest area under receiver operating characteristic curve of 0.819 (95% confidence interval [0.791, 0.848]). This study highlights the potential of radiomics-based ML models for molecular subtype differentiation in pLGG, with per-patient predictions enabling outlier identification and subgroup performance evaluation. Show less

CNS tumors are a significant cause of death in the adolescent and young adult (AYA; age 15-39 years) population; however, these patients often lack standardized treatments. In Canada, we have established national multidisciplinary virtual AYA CNS tumor board rounds (national rounds) to improve and standardize care. From November 2021 to June 2024, 185 AYA patients with CNS tumors were presented from centers nationwide, including 138 patients with glioma. Before case presentation, 5.1% of patients with glioma were taking targeted agents or were enrolled in clinical trials. However, after national rounds, 72.6% of patients with pediatric-type glioma and 45.9% of patients with adult-type glioma were recommended clinical trials and/or targeted agents. Among the 44 patients with glioma who had received radiation therapy before national rounds, only 14 were recommended further radiation. Cumulatively, 68.9% of patients analyzed received a treatment recommendation that represented a change in clinical management compared with their previous treatments. Concurrently, we performed molecular review of 174 AYA CNS tumors during the study time frame. Using TruSight, we identified gene fusions involving Our results suggest that national rounds with centralized molecular review can direct AYA patients with CNS tumors toward targeted agents and clinical trials, while deferring radiation therapy. Taken together, our work details an ongoing effort to improve and standardize care of AYA patients with CNS tumors in Canada. Show less

Leukemic stem cells (LSCs) comprise a very rare cell population that results in the development of acute myeloid leukemia. The selective targeting of drivers in LSCs with small molecule inhibitors holds promise for treatment of acute myeloid leukemia. Recently, we reported the identification of inhibitors of the histone lysine demethylase JMJD1C that preferentially kill MLL rearranged acute leukemia cells. Here, we report the identification of jumonji domain modulator #7 (JDM-7). Surface plasmon resonance analysis showed that JDM-7 binds to JMJD1C and its family homolog JMJD1B. JDM-7 did not significantly suppress cell proliferation in liquid cell culture at higher doses, although it led to a significant decrease in semi-solid colony formation experiments at lower concentrations. Moreover, low doses of JDM-7 did not suppress the proliferation of erythroid progenitor cells. We identified that JDM-7 downregulates the LSC self-renewal gene HOXA9 in leukemia cells. We further found that the structure of JDM-7 is similar to that of tadalafil, a drug approved by the US Food and Drug Administration. Molecular docking and surface plasmon resonance analysis showed that tadalafil binds to JMJD1C. Moreover, similar to JDM-7, tadalafil suppressed colony formation of leukemia cells in semi-solid cell culture at a concentration that did not affect primary umbilical cord blood cells. In summary, we have identified JDM-7 and tadalafil as potential JMJD1C modulators that selectively inhibit the growth of LSCs. Show less

Histone demethylases are promising therapeutic targets as they play fundamental roles for survival of Mixed lineage leukemia rearranged acute leukemia (MLLr AL). Here we focused on the catalytic Jumonji domain of histone H3 lysine 9 (H3K9) demethylase JMJD1C to screen for potential small molecular modulators from 149,519 natural products and 33,765 Chinese medicine components via virtual screening. JMJD1C Jumonji domain inhibitor 4 (JDI-4) and JDI-12 that share a common structural backbone were detected within the top 15 compounds. Surface plasmon resonance analysis showed that JDI-4 and JDI-12 bind to JMJD1C and its family homolog KDM3B with modest affinity. In vitro demethylation assays showed that JDI-4 can reverse the H3K9 demethylation conferred by KDM3B. In vivo demethylation assays indicated that JDI-4 and JDI-12 could induce the global increase of H3K9 methylation. Cell proliferation and colony formation assays documented that JDI-4 and JDI-12 kill MLLr AL and other malignant hematopoietic cells, but not leukemia cells resistant to JMJD1C depletion or cord blood cells. Furthermore, JDI-16, among multiple compounds structurally akin to JDI-4/JDI-12, exhibits superior killing activities against malignant hematopoietic cells compared to JDI-4/JDI-12. Mechanistically, JDI-16 not only induces apoptosis but also differentiation of MLLr AL cells. RNA sequencing and quantitative PCR showed that JDI-16 induced gene expression associated with cell metabolism; targeted metabolomics revealed that JDI-16 downregulates lactic acids, NADP Show less

We report the genetic analysis of a "humanized" hyperlipidemic mouse model for progressive nonalcoholic steatohepatitis (NASH) and fibrosis. Mice carrying transgenes for human apolipoprotein E*3-Leiden and cholesteryl ester transfer protein and fed a "Western" diet were studied on the genetic backgrounds of over 100 inbred mouse strains. The mice developed hepatic inflammation and fibrosis that was highly dependent on genetic background, with vast differences in the degree of fibrosis. Histological analysis showed features characteristic of human NASH, including macrovesicular steatosis, hepatocellular ballooning, inflammatory foci, and pericellular collagen deposition. Time course experiments indicated that while hepatic triglyceride levels increased steadily on the diet, hepatic fibrosis occurred at about 12 weeks. We found that the genetic variation predisposing to NASH and fibrosis differs markedly from that predisposing to simple steatosis, consistent with a multistep model in which distinct genetic factors are involved. Moreover, genome-wide association identified distinct genetic loci contributing to steatosis and NASH. Finally, we used hepatic expression data from the mouse panel and from 68 bariatric surgery patients with normal liver, steatosis, or NASH to identify enriched biological pathways. Conclusion: The pathways showed substantial overlap between our mouse model and the human disease. Show less

The molecular pathogenesis of pediatric ependymoma remains unclear. Our study was designed to identify genetic changes implicated in ependymoma progression. We characterized 59 ependymoma samples (33 at diagnosis and 26 at relapse) using array-comparative genomic hybridization (aCGH). Specific chromosomal imbalances were confirmed by fluorescent in situ hybridization, and candidate genes were assessed by real-time quantitative polymerase chain reaction (qPCR), immunohistochemistry, sequencing, and in vitro functional studies. aCGH analysis revealed a significant increase in genomic imbalances on relapse compared with diagnosis, such as gain of 9qter and 1q (54% v 21% and 12% v 0%, respectively) and loss of 6q (27% v 6%). Supervised tumor classification showed that gain of 9qter was associated with tumor recurrence, age older than 3 years, and posterior fossa location. Using a candidate-gene strategy, we found an overexpression of two potential oncogenes at the locus 9qter: Tenascin-C and Notch1. Moreover, Notch pathway analysis (qPCR) revealed overexpression of Notch ligands, receptors, and target genes (Hes-1, Hey2, and c-Myc), and downregulation of Notch repressor Fbxw7. We confirmed by immunohistochemistry the overexpression of Tenascin-C and Hes-1. We detected Notch1 missense mutations in 8.3% of the tumors (only in the posterior fossa location and in case of 9q33-34 gain). Furthermore, inhibition of Notch pathway with a gamma-secretase inhibitor impaired the growth of ependymoma stem cell cultures. The activation of the Notch pathway and Tenascin-C seem to be important events in ependymoma progression and may represent future targets for therapy. We report, to our knowledge for the first time, recurrent oncogenic mutations in pediatric posterior fossa ependymomas. Show less