A patient with medulloblastoma in its early developmental stage

Pediatric WNT medulloblastoma predisposition in intraoperative blood loss: a retrospective observational cohort study

Introduction

Molecular subgroups influence the vascular architecture within medulloblastomas, particularly the wingless (WNT) subgroup, which contributes to its propensity for primary tumor hemorrhage. Whether this mechanism affects intraoperative blood loss remains unknown. This study aimed to assess the association between WNT medulloblastoma and the predisposition for blood loss.

Methods

This was a retrospective observational study using data from a neuro-oncology center comprising molecular data on patients treated between December 31, 2014, and April 30, 2023. Differences between WNT and other subgroups in the risk of primary outcome-intraoperative blood loss were assessed using multivariable-adjusted linear regression.

Results

Of the 148 patients included in the analysis, 18 patients (12.2%) had WNT, 42 (28.4%) had sonic hedgehog (SHH) TP53-wildtype, 7 (4.7%) had SHH TP53-mutant, and 81 (54.7%) were non-WNT/ non-SHH. The WNT subgroup more frequently underwent primary intratumoral hemorrhage (22% vs. 3.8%; p = 0.011). The median intraoperative blood loss was 400.00 (interquartile range [IQR] 250, 500) mL for WNT and 300.00 [200, 400] mL for the other subgroups (p = 0.136), with an adjusted β of 135.264 (95% confidence intervals [CI], 11.701-258.827; p = 0.032). Similar results were observed in both midline and noninfiltrative margin medulloblastoma.

Discussion

WNT medulloblastoma is typically associated with primary intratumoral hemorrhage and intraoperative blood loss. The validity of determining the surgical approach based on predicted molecular subtypes from imaging data is questionable. However, attempting to engage in risk communication with patients in a molecular-specific way is worthwhile to validate.

Predisposition of Wingless Subgroup Medulloblastoma for Primary Tumor Hemorrhage

BACKGROUND

Primary intratumoral hemorrhage as a presenting sign is rare in children with medulloblastomas but may result in severe complications. Given the distinct properties of molecular medulloblastoma subgroups, the impact on neurosurgical practice has still to be defined.

OBJECTIVE

To investigate both clinical and radiological presentation of intratumoral hemorrhage in medulloblastoma patients in the context of molecular subgroups.

METHODS

Data of all consecutive medulloblastoma patients treated at our institution between 1993 and 2018 (n = 104) were retrospectively reviewed in respect of clinical and radiological presentation as well as molecular subgroups. For cases with available tumor tissue (n = 86), subgroups were assigned by either 450 K methylation array or immunohistochemistry and CTNNB1 sequencing. Available imaging at diagnosis (n = 62) was reviewed by an experienced neuroradiologist.

RESULTS

Within the entire cohort, 4 patients (4%) presented with massive spontaneous hemorrhage. Although no patient died as a direct consequence of hemorrhage, all suffered from serious sequelae. Moreover, 3 additional patients displayed radiological evidence of significant hemorrhage. Interestingly, all 7 cases belonged to the wingless (WNT) subgroup (n = 13), resulting in intratumoral hemorrhage in 54% (7/13) of pediatric WNT medulloblastomas. In contrast, significant hemorrhage was absent in all other molecular subgroups.

CONCLUSION

Our results suggest that a substantial proportion of pediatric WNT medulloblastomas display significant intratumoral hemorrhage at the time of diagnosis. Consequently, the presence of significant hemorrhage in fourth ventricle childhood tumors is suggestive of WNT medulloblastoma and should lead to a less aggressive attempt for total resection in this prognostically favorable tumor type.

Medulloblastoma: Challenges and advances in treatment and research

Background

Medulloblastoma (MB) is a pediatric brain tumor occurring in the posterior fossa. MB is a highly heterogeneous tumor, which can be grouped into four main subgroups: WNT, SHH, Group 3, and Group 4. Each subgroup is different both in its implicated pathways and pathology, as well as how they are treated in the clinic.

Recent Findings

Standard protocol for MB treatment consists of maximal safe resection, followed by craniospinal radiation (in patients 3 years and older) and adjuvant chemotherapy. Advances in clinical stratification of this tumor have allowed establishment of treatment de‐escalation trials aimed at reducing long‐term side effects. However, there have been few advances in identifying novel therapeutic strategies for MB patients due to difficulties in creating chemotherapeutics that can bypass the blood‐brain‐barrier—among other factors. On the other hand, with the help of whole genome sequencing technologies, molecular pathways involved in MB pathogenesis have become clearer and have helped drive MB research. Regardless, this advance in research has yet to translate to the clinic, which may be due to the inability of current in vivo and in vitro models to accurately recapitulate this heterogeneous tumor in humans.

Conclusions

There have been significant advances in knowledge and treatment of medulloblastoma over the last few decades. Whole genome sequencing has helped elucidate clear differences between the subgroups of MB, allowing physicians to better tailor treatments to each patient in an effort to reduce long‐term sequelae. However, there are still many more obstacles to overcome, including less cytotoxic therapies in the clinic and better modeling systems to accurately replicate this disease in the laboratory. Scientists and physicians must work in a more cohesive manner to create translatable results from the laboratory to the clinic—helping improve therapies for medulloblastoma patients.

Clinical significance of polyglutamylation in primary central nervous system lymphoma

The therapeutic response to high-dose methotrexate (HD-MTX) therapy for primary central nervous system lymphoma (PCNSL) varies. Polyglutamylation is a reversible protein modification with a high occurrence rate in tumor cells. MTX incorporated into cells is polyglutamylated and strongly binds to dihydrofolate reductase without competitive inhibition by leucovorin (LV). Tumor cells with high polyglutamylation levels are selectively killed, whereas normal cells with lower polyglutamylation are rescued by LV. We hypothesized that the extent of polyglutamylation in tumor cells determines treatment resistance. Here, we investigated the therapeutic response of PCNSL to HD-MTX therapy with LV rescue based on polyglutamylation status. Among 113 consecutive PCNSL patients who underwent HD-MTX therapy in our department between 2001 and 2014, polyglutamylation was evaluated by immunostaining in 82 cases, with relationships between polyglutamylation and therapeutic response retrospectively examined. Human malignant lymphoma lines were used for in vitro experiments, and folpolyglutamate synthetase (FPGS), which induces polyglutamylation, was knocked down with short-hairpin RNA, and a stable cell line with a low rate of polyglutamylation was established. Cell viability after MTX treatment with LV rescue was evaluated using sodium butyrate (NaBu), a histone-deacetylase inhibitor that induces polyglutamylation by elevating FPGS expression. The complete response rate was significantly higher in the group with polyglutamylation than in the non-polyglutamylation group [58.1% (25/43) and 33.3% (13/39), respectively] (p < 0.05), and progression-free survival was also significantly increased in the group with polyglutamylation (p < 0.01). In vitro, the relief effect of LV after MTX administration was significantly enhanced after FPGS knockdown in al cell lines, whereas enhancement of FPGS expression by NaBu treatment significantly reduced this relief effect. These findings suggested that polyglutamylation could be a predictor of therapeutic response to HD-MTX therapy with LV rescue in PCNSL. Combination therapy with HD-MTX and polyglutamylation-inducing agents might represent a promising strategy for PCNSL treatment.

Imaging Biomarkers for Adult Medulloblastomas: Genetic Entities May Be Identified by Their MR Imaging Radiophenotype

BACKGROUND AND PURPOSE

The occurrence of medulloblastomas in adults is rare; nevertheless, these tumors can be subdivided into genetic and histologic entities each having distinct prognoses. This study aimed to identify MR imaging biomarkers to classify these entities and to uncover differences in MR imaging biomarkers identified in pediatric medulloblastomas.

MATERIALS AND METHODS

Eligible preoperative MRIs from 28 patients (11 women; 22-53 years of age) of the Multicenter Pilot-study for the Therapy of Medulloblastoma of Adults (NOA-7) cohort were assessed by 3 experienced neuroradiologists. Lesions and perifocal edema were volumetrized and multiparametrically evaluated for classic morphologic characteristics, location, hydrocephalus, and Chang criteria. To identify MR imaging biomarkers, we correlated genetic entities sonic hedgehog (SHH) TP53 wild type, wingless (WNT), and non-WNT/non-SHH medulloblastomas (in adults, Group 4), and histologic entities were correlated with the imaging criteria. These MR imaging biomarkers were compared with corresponding data from a pediatric study.

RESULTS

There were 19 SHH TP53 wild type (69%), 4 WNT-activated (14%), and 5 Group 4 (17%) medulloblastomas. Six potential MR imaging biomarkers were identified, 3 of which, hydrocephalus (P = .03), intraventricular macrometastases (P = .02), and hemorrhage (P = .04), when combined, could identify WNT medulloblastoma with 100% sensitivity and 88.3% specificity (95% CI, 39.8%-100.0% and 62.6%-95.3%). WNT-activated nuclear β-catenin accumulating medulloblastomas were smaller than the other entities (95% CI, 5.2-22.3 cm³ versus 35.1-47.6 cm³; P = .03). Hemorrhage was exclusively present in non-WNT/non-SHH medulloblastomas (P = .04; n = 2/5). MR imaging biomarkers were all discordant from those identified in the pediatric cohort. Desmoplastic/nodular medulloblastomas were more rarely in contact with the fourth ventricle (4/15 versus 7/13; P = .04).

CONCLUSIONS

MR imaging biomarkers can help distinguish histologic and genetic medulloblastoma entities in adults and appear to be different from those identified in children.

Meningioma in Down Syndrome

BACKGROUND

Down syndrome comprises multiple malformations and is due to trisomy of chromosome 21. There is epidemiologic evidence that individuals with Down syndrome are at decreased risk for solid tumors including brain tumors. It has been suggested that some genes expressed on the extra copy of chromosome 21 act as tumor suppressor genes and contribute to protection against tumorigenesis.

CASE DESCRIPTION

We report the first case to our knowledge of a patient with Down syndrome, an 8-year-old boy, with an intracranial meningioma, in which the status of chromosome 21 was examined. The diagnosis was based on histologic examination of the surgically resected tumor. Postoperatively, the patient's neurologic status improved, and there was no tumor regrowth in the next 2 years. Fluorescence in situ hybridization for chromosome 22 confirmed high allele loss involving the neurofibromin 2 gene locus, a finding typical in meningiomas. Fluorescence in situ hybridization also revealed chromosome 21 heterogeneity in tumor cells; not only cells with trisomy 21 but also cells with disomy and monosomy 21 were present. All blood cells from the patient manifested trisomy 21.

CONCLUSIONS

Deletion of the chromosome 21 allele may be associated with tumorigenesis of meningioma in Down syndrome. This supports the hypothesis that some genes whose expression is increased on the extra copy of chromosome 21 function as tumor suppressor genes and that they contribute to the reduced tumor incidence in individuals with Down syndrome.