The tumor biology and molecular characteristics of medulloblastoma identifying prognostic factors associated with survival outcomes and prognosis

CLINICAL, DEMOGRAPHIC, ANATOMOPATHOLOGICAL, AND MOLECULAR FINDINGS IN PATIENTS WITH MEDULLOBLASTOMA TREATED IN A SINGLE HEALTH FACILITY

Objective:

To describe the clinical, demographic, anatomopathological, molecular, and survival characteristics of patients with medulloblastoma.

Methods:

Retrospective study based on patient information obtained from the review of medical records. Overall and event-free survival were analyzed using the Kaplan-Meier estimator, and the curves were compared by the log-rank test.

Results:

Among the patients investigated, 70 were male (66%), and age at diagnosis ranged from 2 months to 22 years. The most frequent signs and symptoms were headache (80.8%) and vomiting (75.8%). Regarding treatment, most patients (63.2%) underwent complete surgical resection, with a predominance of classic histology (63.2%). The 5-year overall survival rate was 67.9%, and the 10-year rate was 64.2%. Patients with molecular profile characteristic of the wingless (WNT) subgroup had a better prognosis, with 5-year overall survival of 75%.

Conclusions:

The clinical, demographic, anatomopathological, and molecular characteristics of patients with medulloblastoma described in the present study were mostly similar to those reported in the literature. Patients submitted to complete tumor resection had better clinical outcomes than those who underwent incomplete resection/biopsy. Patients classified as high-risk showed worse overall and event-free survival than those in the standard-risk group, and the presence of metastasis at diagnosis was associated with recurrence.

Exosomal miR-130b-3p targets SIK1 to inhibit medulloblastoma tumorigenesis

Exosomes are an important carrier for cell communication. miRNAs in exosomes are potential biomarkers and therapeutic targets in different types of cancer. However, the role of exosomal miRNAs in medulloblastoma (MB) patients is largely unknown. In this study, we reported that there was a higher level of miR-130b-3p in exosomes derived from MB patient plasma compared with exosomes from healthy control plasma. Exosomes from MB patient plasma could transfer miR-130b-3p to an MB cell line and played suppressor roles for cell proliferation. miR-130b-3p suppressed MB tumorigenesis by targeting a previously unknown target, serine/threonine-protein kinase 1 (SIK1), through the p53 signaling pathways. In addition, we found an unreported role of SIK1 in promoting MB tumor growth and an SIK1 inhibitor could inhibit MB cell proliferation. This research provides new insight into the molecular mechanism of MB and may provide a new therapeutic strategy for MB treatment.

Reproducibility of the NanoString 22-gene molecular subgroup assay for improved prognostic prediction of medulloblastoma

Medulloblastoma is the most frequent malignant brain tumor in children. Four medulloblastoma molecular subgroups, MB_SHH , MB_WNT , MB_GRP3 and MB_GRP4 , have been identified by integrated high-throughput platforms. Recently, a 22-gene panel NanoString-based assay was developed for medulloblastoma molecular subgrouping, but the robustness of this assay has not been widely evaluated. Mutations in the gene for human telomerase reverse transcriptase (hTERT) have been found in medulloblastomas and are associated with distinct molecular subtypes. This study aimed to implement the 22-gene panel in a Brazilian context, and to associate the molecular profile with patients' clinical-pathological features. Formalin-fixed, paraffin-embedded (FFPE) medulloblastoma samples (n = 104) from three Brazilian centers were evaluated. Expression profiling of the 22-gene panel was performed by NanoString and a Canadian series (n = 240) was applied for training phase. hTERT mutations were analyzed by PCR followed by direct Sanger sequencing and the molecular profile was associated with patients' clinicopathological features. Overall, 65% of the patients were male, average age at diagnosis was 18 years and 7% of the patients presented metastasis at diagnosis. The molecular classification was attained in 100% of the cases, with the following frequencies: MB_SHH (n = 51), MB_WNT (n = 19), MB_GRP4 (n = 19) and MB_GRP3 (n = 15). The MB_SHH and MB_GRP3 subgroups were associated with older and younger patients, respectively. The MB_GRP4 subgroup exhibited the lowest 5-year cancer-specific overall survival (OS), yet in the multivariate analysis, only metastasis at diagnosis and surgical resection were associated with OS. hTERT mutations were detected in 29% of the cases and were associated with older patients, increased hTERT expression and MB_SHH subgroup. The 22-gene panel provides a reproducible assay for molecular subgrouping of medulloblastoma FFPE samples in a routine setting and is well-suited for future clinical trials.

Impact of tumor location and fourth ventricle infiltration in medulloblastoma

BACKGROUND

Medulloblastoma is the most common intracranial malignancy in children; with comprehensive treatment the 5-year overall survival (OS) is now greater than 80 %. Only few studies have addressed the relation of tumor location with patient's prognosis. Based on experiences in our institution, we further classified the tumor location. This study aimed to investigate the impact of tumor location and fourth ventricle infiltration in medulloblastoma (MB) prognosis.

METHODS

We retrospectively followed all MB patients at the Beijing Tiantan Hospital between 2004 and 2007 to investigate treatment outcomes and prognostic factors in MB patients. The data of 119 patients were collected. Tumor removal was performed in all patients, and all patients received postsurgical radiotherapy or chemotherapy. The patients were subclassified into three subtypes according to tumor location and tumor infiltration into the fourth ventricular floor (V4 floor). The prognostic factors were analyzed using Kaplan-Meier and Cox regression analysis.

RESULTS

The median follow-up period was 75 months (range, 6-127 months). A total of 65 patients experienced recurrence or progression, and 56 patients were still alive at the time of follow-up. The 5-year progression-free survival (PFS) and overall survival (OS) rates were 47.1 ± 4.6 % and 54.6 ± 4.6 %, respectively.

CONCLUSIONS

According to the multivariate analysis, large cell and anaplastic (LC/A) subtype, patient age, and metastasis were found to be independent prognostic factors. Tumors with V4 floor infiltration exhibited a trend toward recurrence (P = 0.054). This investigation is the largest single-institution study of MB cases in China. The LC/A subtype, patient age, and metastasis were important prognostic factors. V4 floor infiltration was correlated with metastasis and younger age.

Medulloblastoma treatment in a child on dialysis

SUMMARY Managing patients who suffer from both cancer and end-stage renal disease is challenging because there is a paucity of data, especially for children. There are no published reports of adjuvant chemotherapy for medulloblastoma being used in children on dialysis. In this article we describe the case of an Italian 5-year-old boy on hemodialysis for chronic renal failure who presented with a desmoplastic medulloblastoma with extensive nodularity and nuclear β-catenin expression. The patient was treated with craniospinal irradiation after complete surgical resection, followed by six cycles of cyclophosphamide and vincristine. Vincristine was administered at the usual dosage for children with normal kidney function, cyclophosphamide was delivered after dialysis and over the course of the following day, starting with 50% of the commonly used dosage. This is the first case report of chemotherapy given during hemodialysis in a child with medulloblastoma. This treatment proved easy to administer despite the child’s kidney disease and it maintained disease remission with no additional toxicity.

Medulloblastoma expresses CD1d and can be targeted for immunotherapy with NKT cells

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. Current therapies are toxic and not always curative that necessitates development of targeted immunotherapy. However, little is known about immunobiology of this tumor. In this study, we show that MB cells in 9 of 20 primary tumors express CD1d, an antigen-presenting molecule for Natural Killer T cells (NKTs). Quantitative RT-PCR analysis of 61 primary tumors revealed an elevated level of CD1d mRNA expression in a molecular subgroup characterized by an overactivation of Sonic Hedgehog (SHH) oncogene compared with Group 4. CD1d-positive MB cells cross-presented glycolipid antigens to activate NKT-cell cytotoxicity. Intracranial injection of NKTs resulted in regression of orthotopic MB xenografts in NOD/SCID mice. Importantly, the numbers and function of peripheral blood type-I NKTs were preserved in MB patients. Therefore, CD1d is expressed on tumor cells in a subset of MB patients and represents a novel target for immunotherapy.

Nuclear IRS-1 and cancer

The family of insulin receptor substrates (IRS) consists of four proteins (IRS-1-IRS-4), which were initially characterized as typical cytosolic adaptor proteins involved in insulin receptor (IR) and insulin-like growth factor I receptor (IGF-IR) signaling. The first cloned and characterized member of the IRS family, IRS-1, has a predicted molecular weight of 132 kDa, however, as a result of its extensive serine phosphorylation it separates on a SDS gel as a band of approximately 160-185 kDa. In addition to its metabolic and growth-promoting functions, IRS-1 is also suspected to play a role in malignant transformation. The mechanism by which IRS-1 supports tumor growth is not fully understood, and the argument that IRS-1 merely amplifies the signal from the IGF-1R and/or IR requires further investigation. Almost a decade ago, we reported the presence of nuclear IRS-1 in medulloblastoma clinical samples, which express viral oncoprotein, large T-antigen of human polyomavirus JC (JCV T-antigen). This first demonstration of nuclear IRS-1 was confirmed by several other laboratories. Nuclear IRS-1 was also detected by cells expressing the SV40 T-antigen, v-Src, in immortalized fibroblasts stimulated with IGF-I, in hepatocytes, 32D cells, and in an osteosarcoma cell line. More recently, nuclear IRS-1 was detected in breast cancer cells in association with estrogen receptor alpha (ERα), and in JC virus negative medulloblastoma cells expressing estrogen receptor beta (ERβ), further implicating nuclear IRS-1 in cellular transformation. Here, we discuss how nuclear IRS-1 acting on DNA repair fidelity, transcriptional activity, and cell growth can support tumor development and progression.