Molecular-Clinical Correlation in Pediatric Medulloblastoma: A Cohort Series Study of 52 Cases in Taiwan

Medulloblastoma and other neoplasms in patients with heterozygous germline SUFU variants: A scoping review

In 2002, heterozygous suppressor of fused variants (SUFU+/-) in the germline were described to have a tumor suppressor role in the development of pediatric medulloblastoma (MB). Other neoplasms associated with pathologic germline SUFU+/- variants have also been described among patients with basal cell nevus syndrome (BCNS; BCNS is also known as Gorlin syndrome, nevoid basal cell carcinoma [BCC] syndrome or Gorlin-Goltz syndrome; OMIM 109400), an autosomal-dominant cancer predisposition syndrome. The phenotype of patients with germline SUFU+/- variants is very poorly characterized due to a paucity of large studies with long-term follow-up. As such, there is a clinical need to better characterize the spectrum of neoplasms among patients with germline SUFU+/- variants so that clinicians can provide accurate counseling and optimize tumor surveillance strategies. The objective of this study is to perform a scoping review to map the evidence on the rate of medulloblastoma and to describe the spectrum of other neoplasms among patients with germline SUFU+/- variants. A review of all published literature in PubMed (MEDLINE), EMBASE, Cochrane, and Web of Science were searched from the beginning of each respective database until October 9, 2021. Studies of pediatric and adult patients with a confirmed germline SUFU+/- variant who were evaluated for the presence of any neoplasm (benign or malignant) were included. There were 176 patients (N = 30 studies) identified with a confirmed germline SUFU+/- variant who met inclusion criteria. Data were extracted from two cohort studies, two case-control studies, 18 case series, and eight case reports. The median age at diagnosis of a germline SUFU+/- variant was 4.5 years where 44.4% identified as female and 13.4% of variants were de novo. There were 34 different neoplasms (benign and malignant) documented among patients with confirmed germline SUFU+/- variants, and the most common were medulloblastoma (N = 59 patients), BCC (N = 21 patients), and meningioma (N = 19 patients). The median age at medulloblastoma diagnosis was 1.42 years (range 0.083-3; interquartile range 1.2). When data were available for these three most frequent neoplasms (N = 95 patients), 31 patients (32.6%) had neither MB, BCC nor meningioma; 51 patients (53.7%) had one of medulloblastoma or BCC or meningioma; eight patients (8.4%) had two of medulloblastoma or BCC or meningioma, and five patients (5.3%) had medulloblastoma and BCC and meningioma. This is the first study to synthesize the data on the frequency and spectrum of neoplasms specifically among patients with a confirmed germline SUFU+/- variant. This scoping review is a necessary step forward in optimizing evidence-based tumor surveillance strategies for medulloblastoma and estimating the risk of other neoplasms that could impact patient outcomes.

Cerebellar phenotypes in germline PTEN mutation carriers

PTEN hamartoma tumour syndrome (PHTS) comprises different hereditary conditions caused by germline PTEN mutations, predisposing to the development of multiple hamartomas in many body tissues and also increasing the risk of some types of cancer. Cerebellar involvement in PHTS patients has been long known due to the development of a pathognomonic cerebellar hamartoma (known as dysplastic gangliocytoma of the cerebellum or Lhermitte-Duclos disease). Recently, a crucial role of the cerebellum has been highlighted in the pathogenesis of autism spectrum disorders, now recognised as a phenotype expressed in a variable percentage of PHTS children. In addition, rare PTEN variants are indeed identified in medulloblastoma as well, even if they are less frequent than other germline gene mutations. The importance of PTEN and its downstream signalling enzymatic pathways, PI3K/AKT/mTOR, has been studied at different levels in both human clinical settings and animal models, not only leading to a better understanding of the pathogenesis of different disorders but, most importantly, to identify potential targets for specific therapies. In particular, PTEN integrity makes an important contribution to the normal development of tissue architecture in the nervous system, including the cerebellum. Thus, in patients with PTEN germline mutations, the cerebellum is an affected organ that is increasingly recognised in different disorders, whereas, in animal models, cerebellar Pten loss causes a variety of functional and histological alterations. In this review, we summarise the range of cerebellar involvement observed in PHTS and its relationships with germline PTEN mutations, along with the phenotypes expressed by murine models with PTEN deficiency in cerebellar tissue.

Clinical and Molecular Features in Medulloblastomas Subtypes in Children in a Cohort in Taiwan

Simple Summary

Medulloblastoma (MB) was classified into four subgroups: WNT, SHH, group 3, and group 4. In 2017, 12 subtypes within 4 subgroups and 8 subtypes within non-WNT/non-SHH subgroups according to the heterogenous features were announced. In this study, we aimed to identify the heterogeneity of molecular features for discovering subtype specific factors linked to diagnosis and prognosis. We retrieved 70 MBs to perform RNA sequencing and a DNA methylation array. Integrated with clinical annotations, we classified 12 subtypes of pediatric MBs. We found that M2 macrophages were enriched in SHH β, which correlated with good outcomes of SHH MBs. The high infiltration of M2 macrophages may be an indicator of a favorable prognosis and therapeutic target for SHH MBs. Furthermore, C11orf95-RELA fusion was observed to be associated with recurrence and a poor prognosis. These results will contribute to the establishment of a molecular diagnosis linked to prognostic factors of relevance for MBs.

Abstract

Medulloblastoma (MB) was classified into four molecular subgroups: WNT, SHH, group 3, and group 4. In 2017, 12 subtypes within 4 subgroups and 8 subtypes within non-WNT/non-SHH subgroups according to the differences of clinical features and biology were announced. In this study, we aimed to identify the heterogeneity of molecular features for discovering subtype specific factors linked to diagnosis and prognosis. We retrieved 70 MBs in children to perform RNA sequencing and a DNA methylation array in Taiwan. Integrated with clinical annotations, we achieved classification of 12 subtypes of pediatric MBs in our cohort series with reference to the other reported series. We analyzed the correlation of cell type enrichment in SHH MBs and found that M2 macrophages were enriched in SHH β, which related to good outcomes of SHH MBs. The high infiltration of M2 macrophages may be an indicator of a favorable prognosis and therapeutic target for SHH MBs. Furthermore, C11orf95-RELA fusion was observed to be associated with recurrence and a poor prognosis. These results will contribute to the establishment of a molecular diagnosis linked to prognostic indicators of relevance and help to promote molecular-based risk stratified treatment for MBs in children.

Enrichment of Tumor-Infiltrating B Cells in Group 4 Medulloblastoma in Children

Medulloblastoma (MB) is the most common malignant brain tumor in children. It is classified into core molecular subgroups (wingless activated (WNT), sonic hedgehog activated (SHH), Group 3 (G3), and Group 4 (G4)). In this study, we analyzed the tumor-infiltrating immune cells and cytokine profiles of 70 MB patients in Taiwan using transcriptome data. In parallel, immune cell composition in tumors from the SickKids cohort dataset was also analyzed to confirm the findings. The clinical cohort data showed the WNT and G4 MB patients had lower recurrence rates and better 5-year relapse-free survival (RFP) compared with the SHH and G3 MB patients, among the four subgroups of MB. We found tumor-infiltrating B cells (TIL-Bs) enriched in the G4 subgroups in the Taiwanese MB patients and the SickKids cohort dataset. In the G4 subgroups, the patients with a high level of TIL-Bs had better 5-year overall survival. Mast cells presented in G4 MB tumors were positively correlated with TIL-Bs. Higher levels of CXCL13, IL-36γ, and CCL27 were found compared to other subgroups or normal brains. These three cytokines, B cells and mast cells contributed to the unique immune microenvironment in G4 MB tumors. Therefore, B-cell enrichment is a G4-subgroup-specific immune signature and the presence of B cells may be an indicator of a better prognosis in G4 MB patients.

Integration of immunohistochemistry, RNA sequencing, and multiplex ligation-dependent probe amplification for molecular classification of pediatric medulloblastoma

BACKGROUND

Medulloblastoma (MB) is commonly classified into four molecular groups, that is, WNT, SHH, group 3, and group 4, for prognostic and therapeutic purposes.

METHODS

Here we applied immunohistochemistry (IHC) and RNA sequencing (RNA-seq) for the molecular classification of MB, and utilized multiplex ligation-dependent probe amplification (MLPA) to determine chromosomal alterations and specific gene amplifications.

RESULTS

We retrospectively enrolled 37 pediatric MB patients. Twenty-three had genomic material available for gene/RNA analysis. For IHC, β-catenin, GAB1, and YAP were the biomarkers to segregate MB into three subgroups, WNT (1/23), SHH (5/23), and non-WNT/non-SHH (17/23). However, four cases (17.3%) were found to be misclassified after analysis by RNA-seq. The result of MLPA revealed two group 3 tumors carrying MYC amplification, and three SHH tumors harboring MYCN amplification. While IHC provided rapid subgroup stratification, it might result in incorrect subgrouping. Thus, validation of the IHC result with genomic data analysis by RNA-seq or other tools would be preferred. In addition, MLPA can detect important genetic alterations and is helpful for the identifications of high-risk patients.

CONCLUSIONS

Our study revealed that integration of these diagnostic tools can provide a precise and timely classification of MB, optimizing an individualized, risk-directed postoperative adjuvant therapy for these patients. This workflow can be applied in a countrywide fashion to guide future clinical trials for patients with MB.

Notch signaling and natural killer cell infiltration in tumor tissues underlie medulloblastoma prognosis

Medulloblastoma is the most common embryonic brain tumor in children. We investigated a cohort of 52 Asian medulloblastoma patients aged between 0 and 19 years old, who received surgical resections and post-resection treatments in the Taipei Medical University Hospital and the Taipei Veterans General Hospital. Genome-wide RNA sequencing was performed on fresh-frozen surgical tissues. These data were analyzed using the CIBERSORTx immune deconvolution software. Two external clinical and molecular datasets from United States (n = 62) and Canada (n = 763) were used to evaluate the transferability of the gene-signature scores across ethnic populations. The abundance of 13 genes, including DLL1, are significantly associated with overall survival (All Cox regression P < 0.001). A gene-signature score was derived from the deep transcriptome, capable of indicating patients’ subsequent tumor recurrence (Hazard Ratio [HR] 1.645, confidence interval [CI] 1.337–2.025, P < 0.001) and mortality (HR 2.720, CI 1.798–4.112, P < 0.001). After the adjustment of baseline clinical factors, the score remains indicative of recurrence-free survival (HR 1.604, CI 1.292–1.992, P < 0.001) and overall survival (HR 2.781, CI 1.762–4.390, P < 0.001). Patients stratified by this score manifest not only distinct prognosis but also different molecular characteristics: Notch signaling ligands and receptors are comparatively overexpressed in patients with poorer prognosis, while tumor infiltrating natural killer cells are more abundant in patients with better prognosis. Additionally, immunohistochemical staining showed the DLL1 protein, a major ligand in the Notch signaling pathway, and the NCAM1 protein, a representative biomarker of natural killer cells, are present in the surgical tissues of patients of four molecular subgroups, WNT, SHH, Group 3 and Group 4. NCAM1 RNA level is also positively associated with the mutation burden in tumor (P = 0.023). The gene-signature score is validated successfully in the Canadian cohort (P = 0.009) as well as its three molecular subgroups (SHH, Group 3 and Group 4; P = 0.047, 0.018 and 0.040 respectively). In conclusion, pediatric medullablastoma patients can be stratified by gene-signature scores with distinct prognosis and molecular characteristics. Ligands and receptors of the Notch signaling pathway are overexpressed in the patient stratum with poorer prognosis. Tumor infiltrating natural killer cells are more abundant in the patient stratum with better prognosis.

Magnetic resonance radiomics features and prognosticators in different molecular subtypes of pediatric Medulloblastoma

Purpose

Medulloblastoma (MB) is a highly malignant pediatric brain tumor. In the latest classification, medulloblastoma is divided into four distinct groups: wingless (WNT), sonic hedgehog (SHH), Group 3, and Group 4. We analyzed the magnetic resonance imaging radiomics features to find the imaging surrogates of the 4 molecular subgroups of MB.

Material and methods

Frozen tissue, imaging data, and clinical data of 38 patients with medulloblastoma were included from Taipei Medical University Hospital and Taipei Veterans General Hospital. Molecular clustering was performed based on the gene expression level of 22 subgroup-specific signature genes. A total 253 magnetic resonance imaging radiomic features were generated from each subject for comparison between different molecular subgroups.

Results

Our cohort consisted of 7 (18.4%) patients with WNT medulloblastoma, 12 (31.6%) with SHH tumor, 8 (21.1%) with Group 3 tumor, and 11 (28.9%) with Group 4 tumor. 8 radiomics gray-level co-occurrence matrix texture (GLCM) features were significantly different between 4 molecular subgroups of MB. In addition, for tumors with higher values in a gray-level run length matrix feature—Short Run Low Gray-Level Emphasis, patients have shorter survival times than patients with low values of this feature (p = 0.04). The receiver operating characteristic analysis revealed optimal performance of the preliminary prediction model based on GLCM features for predicting WNT, Group 3, and Group 4 MB (area under the curve = 0.82, 0.72, and 0.78, respectively).

Conclusion

The preliminary result revealed that 8 contrast-enhanced T1-weighted imaging texture features were significantly different between 4 molecular subgroups of MB. Together with the prediction models, the radiomics features may provide suggestions for stratifying patients with MB into different risk groups.

Genomic and Transcriptomic Analyses Reveals ZNF124 as a Critical Regulator in Highly Aggressive Medulloblastomas

Medulloblastoma (MB) is the most common malignant pediatric brain tumor, however, the mechanisms underlying tumorigenesis in different MB subgroups remain incompletely understood. Although previous studies of MB predisposition have been conducted in tertiary referral centers primarily in Caucasian cohorts, it is not unclear clear whether there exist population-specific genetic alterations in MBs. In this study, we investigated the contribution of genomic and transcriptomic alterations to the risk of malignant MB in the Chinese population (designated as the Asian cohort). We analyze the genomic and transcriptomic alterations of the Asian MB cohort by using a combination of whole-exome sequencing (WES) and RNA-deep-sequencing. In addition, we integrate publicly available data with the Asian MB cohort and identify a subset of potential MB-driving genes specifically enriched in each of the MB subgroups. We further characterize a newly identified group-3-enriched transcriptional regulator, ZNF124, and demonstrate that ZNF124 is critical for the growth of the most aggressive group-3 MB cells. Together, our analyses indicate conserved yet distinct genetic alterations and gene expression patterns of MBs between different ethnic groups. Our studies further provide an important resource for identifying potential tumor-driving factors in MBs, enhancing our understanding of the disease process for developing ethnically targeted therapies in patients with MB.