Sporadic and Lynch syndrome-associated mismatch repair-deficient brain tumors

MSH2, MSH6, MLH1, and PMS2 immunohistochemistry as highly sensitive screening method for DNA mismatch repair deficiency syndromes in pediatric high-grade glioma

Pediatric high-grade glioma (pedHGG) can occur as first manifestation of cancer predisposition syndromes resulting from pathogenic germline variants in the DNA mismatch repair (MMR) genes MSH2, MSH6, MLH1, and PMS2. The aim of this study was to establish a generalized screening for Lynch syndrome and constitutional MMR deficiency (CMMRD) in pedHGG patients, as the detection of MMR deficiencies (MMRD) may enable the upfront therapeutic use of checkpoint inhibitors and identification of variant carriers in the patients' families. We prospectively enrolled 155 centrally reviewed primary pedHGG patients for MMR-immunohistochemistry (IHC) as part of the HIT-HGG-2013 trial protocol. MMR-IHC results were subsequently compared to independently collected germline sequencing data (whole exome sequencing or pan-cancer DNA panel next-generation sequencing) available in the HIT-HGG-2013, INFORM, and MNP2.0 trials. MMR-IHC could be successfully performed in 127/155 tumor tissues. The screening identified all present cases with Lynch syndrome or CMMRD (5.5%). In addition, MMR-IHC also detected cases with exclusive somatic MMR gene alterations (2.3%), including MSH2 hypermethylation as an alternative epigenetic silencing mechanism. Most of the identified pedHGG MMRD patients had no family history of MMRD, and thus, they represented index patients in their families. Cases with regular protein expression in MMR-IHC never showed evidence for MMRD in DNA sequencing. In conclusion, MMR-IHC presents a cost-effective, relatively widely available, and fast screening method for germline MMRD in pedHGG with high sensitivity (100%) and specificity (96%). Given the relatively high prevalence of previously undetected MMRD cases among pedHGG patients, we strongly recommend incorporating MMR-IHC into routine diagnostics.

Genetic and clinical characteristics of genetic tumor syndromes in the central nervous system cancers: Implications for clinical practice

Recognizing individuals with Genetic tumor syndromes (GTS) in the primary central nervous system (CNS) tumors is crucial for optimizing proper genetic counseling and improving therapeutics and clinical care. We retrospectively analyzed the GTS in a Chinese CNS tumor cohort and examined the molecular characteristics and their clinical significance for diagnostic and therapeutic purposes. Our study identified 34 categories of GTS in 258 patients with CNS tumors. The gene with the highest germline pathogenic or likely pathogenic mutation frequency was TP53, followed by MSH2, NF1, and BRCA2. The top five GTS in CNS tumors showed high genetic heterogeneity GTS analysis reclassifies CNS tumors as "NEC." 53.88% of patients diagnosed with GTS harbor potential precision oncology therapy target mutations. The results of our study deepen our understanding of CNS tumors, provide a reference direction for the future design of clinical trials, and further expect to improve disease entire process management in CNS tumors.

Primary mismatch repair-deficient IDH-mutant astrocytoma in child: Unusual entity

INTRODUCTION

"Primary Mismatch Repair-Deficient IDH-mutant Astrocytoma" (PMMRDIA) is a newly identified high-grade glioma with a poor prognosis. It has not been officially recognized as a distinct entity in the 5th edition of the WHO Classification of Central Nervous System Tumors 2021, making its diagnosis challenging.

CASE PRESENTATION

To highlight this entity, we present the case of a 7-year-old boy with a family history of cerebral tumor among the father's relatives and first-degree parental consanguinity. He experienced increased intracranial hypertension and inguinal café-au-lait macules. Brain imaging revealed a cystic and solid mass with irregular enhancement in the left parietal lobe, indicating a possible Pilocytic astrocytoma. The final diagnosis of PMMRDIA was confirmed through histological, immunohistochemical, and molecular analysis.

CLINICAL DISCUSSION

This tumor is mainly observed in children and is characterized by microsatellite instability (MSI) and high tumor mutational burden (TMB). MSI is known to occur in recurrent IDH-mutant gliomas as a resistance mechanism towards alkylating chemotherapy.

CONCLUSION

In PMMRDIA, MSI can be a good predictive biomarker for responding to immunotherapy, which could improve the outcome of these children.

Genetic and epigenetic instability as an underlying driver of progression and aggressive behavior in IDH-mutant astrocytoma

In recent years, the classification of adult-type diffuse gliomas has undergone a revolution, wherein specific molecular features now represent defining diagnostic criteria of IDH-wild-type glioblastomas, IDH-mutant astrocytomas, and IDH-mutant 1p/19q-codeleted oligodendrogliomas. With the introduction of the 2021 WHO CNS classification, additional molecular alterations are now integrated into the grading of these tumors, given equal weight to traditional histologic features. However, there remains a great deal of heterogeneity in patient outcome even within these established tumor subclassifications that is unexplained by currently codified molecular alterations, particularly in the IDH-mutant astrocytoma category. There is also significant intercellular genetic and epigenetic heterogeneity and plasticity with resulting phenotypic heterogeneity, making these tumors remarkably adaptable and robust, and presenting a significant barrier to the design of effective therapeutics. Herein, we review the mechanisms and consequences of genetic and epigenetic instability, including chromosomal instability (CIN), microsatellite instability (MSI)/mismatch repair (MMR) deficits, and epigenetic instability, in the underlying biology, tumorigenesis, and progression of IDH-mutant astrocytomas. We also discuss the contribution of recent high-resolution transcriptomics studies toward defining tumor heterogeneity with single-cell resolution. While intratumoral heterogeneity is a well-known feature of diffuse gliomas, the contribution of these various processes has only recently been considered as a potential driver of tumor aggressiveness. CIN has an independent, adverse effect on patient survival, similar to the effect of histologic grade and homozygous CDKN2A deletion, while MMR mutation is only associated with poor overall survival in univariate analysis but is highly correlated with higher histologic/molecular grade and other aggressive features. These forms of genomic instability, which may significantly affect the natural progression of these tumors, response to therapy, and ultimately clinical outcome for patients, are potentially measurable features which could aid in diagnosis, grading, prognosis, and development of personalized therapeutics.

NTRK-fused central nervous system tumours: clinicopathological and genetic insights and response to TRK inhibitors

Background Neurotrophic tropomyosin receptor kinase (NTRK) gene fusions are found in 1% of gliomas across children and adults. TRK inhibitors are promising therapeutic agents for NTRK-fused gliomas because they are tissue agnostic and cross the blood-brain barrier (BBB). Methods We investigated twelve NGS-verified NTRK-fused gliomas from a single institute, Seoul National University Hospital. Results The patient cohort included six children (aged 1-15 years) and six adults (aged 27-72 years). NTRK2 fusions were found in ten cerebral diffuse low-grade and high-grade gliomas (DLGGs and DHGGs, respectively), and NTRK1 fusions were found in one cerebral desmoplastic infantile ganglioglioma and one spinal DHGG. In this series, the fusion partners of NTRK2 were HOOK3, KIF5A, GKAP1, LHFPL3, SLMAP, ZBTB43, SPECC1L, FKBP15, KANK1, and BCR, while the NTRK1 fusion partners were TPR and TPM3. DLGGs tended to harbour only an NTRK fusion, while DHGGs exhibited further genetic alterations, such as TERT promoter/TP53/PTEN mutation, CDKN2A/2B homozygous deletion, PDGFRA/KIT/MDM4/AKT3 amplification, or multiple chromosomal copy number aberrations. Four patients received adjuvant TRK inhibitor therapy (larotrectinib, repotrectinib, or entrectinib), among which three also received chemotherapy (n = 2) or proton therapy (n = 1). The treatment outcomes for patients receiving TRK inhibitors varied: one child who received larotrectinib for residual DLGG maintained stable disease. In contrast, another child with DHGG in the spinal cord experienced multiple instances of tumour recurrence. Despite treatment with larotrectinib, ultimately, the child died as a result of tumour progression. An adult patient with glioblastoma (GBM) treated with entrectinib also experienced tumour progression and eventually died. However, there was a successful outcome for a paediatric patient with DHGG who, after a second gross total tumour removal followed by repotrectinib treatment, showed no evidence of disease. This patient had previously experienced relapse after the initial surgery and underwent autologous peripheral blood stem cell therapy with carboplatin/thiotepa and proton therapy. Conclusions Our study clarifies the distinct differences in the pathology and TRK inhibitor response between LGG and HGG with NTRK fusions.

Immunohistochemical Approach to Mismatch Repair Deficiency in Pediatric High-Grade Glioma

Knowledge of the molecular pathways of pediatric high-grade gliomas is increasing. Gliomas with mismatch repair deficiency do not currently comprise a distinct group, but data on this topic have been accumulating in recent publications. Immunohistochemistry can effectively determine mismatch repair status, indirectly suggesting the microsatellite instability of the tumor. This study aimed to determine the number of mismatch repair-deficient pediatric high-grade gliomas in a tertiary institution and assess the relationship between the survival and mismatch repair status of the patients. It also aimed to assess the potential for further clinical studies including immunotherapy. Of 24 patients with high-grade gliomas, 3 deceased patients were mismatch repair-deficient. Mismatch repair deficiency was significantly associated with shorter survival ( P =0.004). Immunotherapy trials need to progress, and patients with mismatch repair-deficient pediatric high-grade gliomas are the most suitable candidates for such studies.

Association between the Anatomical Location of Glioblastoma and Its Evaluation with Clinical Considerations: A Systematic Review and Meta-Analysis

Background: Glioblastoma is a primary malignant brain tumor; it is aggressive with a high degree of malignancy and unfavorable prognosis and is the most common type of malignant brain tumor. Glioblastomas can be located in the brain, cerebellum, brainstem, and spinal cord, originating from glial cells, particularly astrocytes. Methods: The databases MEDLINE, Scopus, Web of Science, Google Scholar, and CINAHL were researched up to January 2024. Two authors independently performed the search, study selection, and data extraction. Methodological quality was evaluated with an assurance tool for anatomical studies (AQUA). The statistical mean, standard deviation, and difference of means calculated with the Student's t-test for presence between hemispheres and presence in the frontal and temporal lobes were analyzed. Results: A total of 123 studies met the established selection criteria, with a total of 6224 patients. In relation to the mean, GBM between hemispheres had a mean of 33.36 (SD 58.00) in the right hemisphere and a mean of 34.70 (SD 65.07) in the left hemisphere, due to the difference in averages between hemispheres. There were no statistically significant differences, p = 0.35. For the comparison between the presence of GBM in the frontal lobe and the temporal lobe, there was a mean in the frontal lobe of 23.23 (SD 40.03), while in the temporal lobe, the mean was 22.05 (SD 43.50), and for the difference in means between the frontal lobe and the temporal lobe, there was no statistically significant difference for the presence of GBM, p = 0.178. Conclusions: We believe that before a treatment, it will always be correct to know where the GBM is located and how it behaves clinically, in order to generate correct conservative or surgical treatment guidelines for each patient. We believe that more detailed studies are also needed to show why GBM is associated more with some regions than others, despite the brain structure being homologous to other regions in which GMB occurs less frequently, which is why knowing its predominant presence in brain regions is very important.

Pediatric high grade gliomas: A comprehensive histopathological, immunohistochemical and molecular integrated approach in routine practice

Pediatric high grade gliomas have undergone remarkable changes in recent time with discovery of new molecular pathways. They have been added separately in current WHO 2021 blue book. All the entities show characteristic morphology and immunohistochemistry. Methylation data correctly identifies these entities into particular group of clusters. The pediatric group high grade glioma comprises- Diffuse midline glioma, H3K27-altered; Diffuse hemispheric glioma, H3G34-mutant; Diffuse pediatric-type high-grade glioma, H3-wild type & IDH-wild type; Infant hemispheric glioma and Epithelioid glioblastoma/Grade 3 pleomorphic xanthoastrocytoma and very rare IDH-mutant astrocytoma. However it is not always feasible to perform these molecular tests where cost-effective diagnosis is a major concern. Here we discuss the major entities with their characteristic histopathology, immunohistochemistry and molecular findings that may help to reach to suggest the diagnosis and help the clinician for appropriate treatment strategies. We have also made a simple algorithmic flow chart integrated with histopathology, immunohistochemistry and molecular characteristics for better understanding.

A case report: Gliosarcoma associated with a germline heterozygous mutation in MSH2

Gliosarcoma is a rare subtype of glioblastoma (GBM) with a shorter medical history and a worse prognosis compared to other Grade 4 gliomas. Most gliosarcomas are sporadic, but it is undeniable that a small percentage are linked to germline mutations and several inherited cancer susceptibility syndromes, including Lynch Syndrome (LS). The authors present a case of a primary mismatch repair-deficient gliosarcoma in LS. A 54-year-old Chinese male patient was admitted to the hospital with a history of facial asymmetry for over 1 month and right temporo-occipital pain for 5 days. Head MRI revealed a complex mass lesion in the right frontoparietal region, consisting of cystic and solid components. The patient's history of colon malignancy and family history of rectal carcinoma were noteworthy. Postoperative pathology indicated the presence of gliosarcoma with high-frequency microsatellite instability (MSI-H) and mismatch repair deficiency (MMRD). Further genetic testing results confirmed a germline heterozygous mutation in MSH2, which is considered the gold standard for diagnosing LS. This case report enriches the existing literature on germline MSH2 mutations and gliosarcomas. It highlights the importance for neurosurgeons to consider possible hereditary disorders when treating patients with a history of concurrent tumors outside the nervous system. Genetic testing is crucial for further identification of such disorders.

Clinicopathological and molecular landscape of 5-year IDH-wild-type glioblastoma survivors: A multicentric retrospective study

Five-year glioblastoma (GBM) survivors (LTS) are the minority of the isocitrate dehydrogenase (IDH)-wild-type GBM patients, and their molecular fingerprint is still largely unexplored. This multicenter retrospective study analyzed a large LTS-GBM cohort from nine Italian institutions and molecularly characterized a subgroup of patients by mutation, DNA methylation (DNAm) and copy number variation (CNV) profiling, comparing it to standard survival GBM. Mutation scan allowed the identification of pathogenic variants in most cases, showing a similar mutational spectrum in both groups, and highlighted TP53 as the most commonly mutated gene in the LTS group. We confirmed DNAm as a valuable tool for GBM classification with a diagnostic refinement by using brain tumor classifier v12.5. LTS were more heterogeneous with more cases classified as diffuse pediatric high-grade glioma subtypes and having peculiar CNVs. We observed a global higher methylation in CpG islands and in gene promoters of LTS with methylation levels of distinct gene promoters correlating with prognosis.

Therapeutic Strategies for Gliomas Associated With Cancer Predisposition Syndromes

PURPOSE

The purpose of this article was to provide an overview of syndromic gliomas.

DESIGN

The authors conducted a nonsystematic literature review.

RESULTS

Cancer predisposition syndromes (CPSs) are genetic conditions that increase one's risk for certain types of cancer compared with the general population. Syndromes that can predispose one to developing gliomas include neurofibromatosis, Li-Fraumeni syndrome, Lynch syndrome, and tuberous sclerosis complex. The standard treatment for sporadic glioma may involve resection, radiation therapy, and/or alkylating chemotherapy. However, DNA-damaging approaches, such as radiation and alkylating agents, may increase the risk of secondary malignancies and other complications in patients with CPSs. In some cases, depending on genetic aberrations, targeted therapies or immunotherapeutic approaches may be considered. Data on clinical characteristics, therapeutic strategies, and prognosis of syndromic gliomas remain limited.

CONCLUSION

In this review, we provide an overview of syndromic gliomas with a focus on management for patients with CPSs and the role of novel treatments that can be considered.

Adult glioblastoma with Lynch syndrome-associated mismatch repair deficiency forms a distinct high-risk molecular subgroup

Glioblastoma is the most frequent and malignant primary brain tumor. Although the survival is generally dismal for glioblastoma patients, risk stratification and the identification of high-risk subgroups is important for prompt and aggressive management. The G1-G7 molecular subgroup classification based on the MAPK pathway activation has offered for the first time a non-redundant, all-inclusive classification of adult glioblastoma. Five patients from the large, 218-patient, prospective cohort showed germline mutations in mismatch repair (MMR) genes (Lynch syndrome) and a significantly worse median survival of 3.25 months post-surgery than those from the G1/EGFR and G3/NF1 major subgroups, or from the rest of the cohort adjusted for age. These rare tumors were assigned to a new subgroup, G3/MMR, a G3/NF1 subgroup spin-off, as they generally show genomic alterations leading to RAS activation, such as NF1 and PTPN11 mutations. An integrated clinical, histologic and molecular analysis of the G3/MMR tumors showed distinct characteristics as compared to other glioblastomas, including those with iatrogenic high tumor mutation burden (TMB), warranting a separate subgroup. Prior history of cancer, midline location or multifocality, presence of multinucleated giant cells (MGCs), positive p53 and MMR immunohistochemistry, and specific molecular characteristics, including high TMB, MSH2/MSH6 alterations, biallelic TP53 Arg mutations and co-occurring PIK3CA p.R88Q and PTEN alterations, alert to this high-risk G3/MMR subgroup. The MGCs and p53 immunohistochemistry analysis in G1-G7 subgroups showed that one in 7 tumors with these characteristics is a G3/MMR glioblastoma. The FDA-approved first-line therapy for many advanced solid tumors consists of nivolumab-ipilimumab immune checkpoint inhibitors. One G3/MMR patient received this regimen and survived much longer than the rest, setting a proof-of-principle example for the treatment of these very aggressive G3/MMR glioblastomas.

Lynch Syndrome-Associated Glioblastoma Treated With Concomitant Chemoradiotherapy and Immune Checkpoint Inhibitors: Case Report and Review of Literature

Lynch syndrome (LS) is an autosomal dominant disorder caused by mutations in mismatch repair (MMR) genes and is also known to be associated with glioblastomas. The efficacy of immunotherapy for LS-associated glioblastomas remains unknown. Herein, we report a rare case of LS-associated glioblastoma, treated with chemotherapy using immune checkpoint inhibitors (ICI). A 41-year-old female patient presented with headaches and sensory disturbances in the right upper limb for 6 weeks. She had been treated for rectal cancer and had a family history of LS. MRI revealed two ring-enhancing lesions in the left precentral gyrus. She underwent subtotal resection, leading to a pathological diagnosis of isocitrate dehydrogenase wild-type glioblastoma. She received daily administration of (temozolomide, 75 mg/m²) and concurrent radiotherapy (60 Gy) postoperatively. However, the tumor recurred 1 year after the initial treatment. A molecular genetic study showed high microsatellite instability (MSI), and she was treated with pembrolizumab therapy. Disease progression occurred despite six cycles of pembrolizumab therapy and radiotherapy at the dose of 40 Gy. She died due to glioblastoma progression 19 months after the initial treatment. The present case demonstrates that some LS-associated glioblastomas may be resistant to ICI despite high MSI, possibly because of intratumor heterogeneity related to MMR deficiency.

SOMATIC DEFICIENT MISMATCH REPAIR ASSESSED BY IMMUNOHISTOCHEMISTRY AND CLINICAL FEATURES IN BRAZILIAN GLIOBLASTOMA PATIENTS

BACKGROUND

Glioblastoma (GBM) is the most frequent primary malignant CNS tumor. Deficient mismatch repair (dMMR) is associated with better prognosis and is a biomarker for immunotherapy. Evaluation of MMR by immunohistochemistry (IHC) is accessible, cost effective, sensitive, and specific.

AIM

Our objective was to investigate MMR proteins in adult GBM patients.

MATERIALS AND METHODS

We retrospectively analyzed 68 GBM samples to evaluate the proficiency of MMR genes expression assessed by IHC. Clinicopathologic and molecular features were compared in proficient (pMMR) or dMMR.

RESULTS

10 (14.7%) samples showed dMMR, and the most frequent was MSH6 (100%) followed by MSH2, PMS2, and MLH1. We observed heterogeneous expression of dMMR in 5 GBMs. The median overall survival did not differ between pMMR (19.8 months; 0.2-30) and dMMR (16.9 months; 6.4-27.5) (p = 0.31). We observed a significantly higher overall survival associated with gross total resection compared to subtotal resection or biopsy (30.7 vs. 13.6 months, p = 0.02) and MGMT methylated status (29.6 vs. 19.8 months, p = 0.049). At the analysis time, 10 patients were still alive, all in the pMMR group.

CONCLUSIONS

Our data demonstrated dMMR phenotype assessed by IHC in an expressive portion of GBM patients, however without significant impact on overall survival.

Germline Variants in Cancer Predisposition Genes in Pediatric Patients with Central Nervous System Tumors

Central nervous system (CNS) tumors comprise around 20% of childhood malignancies. Germline variants in cancer predisposition genes (CPGs) are found in approximately 10% of pediatric patients with CNS tumors. This study aimed to characterize variants in CPGs in pediatric patients with CNS tumors and correlate these findings with clinically relevant data. Genomic DNA was isolated from the peripheral blood of 51 pediatric patients and further analyzed by the next-generation sequencing approach. Bioinformatic analysis was done using an "in-house" gene list panel, which included 144 genes related to pediatric brain tumors, and the gene list panel Neoplasm (HP:0002664). Our study found that 27% of pediatric patients with CNS tumors have a germline variant in some of the known CPGs, like ALK, APC, CHEK2, ELP1, MLH1, MSH2, NF1, NF2 and TP53. This study represents the first comprehensive evaluation of germline variants in pediatric patients with CNS tumors in the Western Balkans region. Our results indicate the necessity of genomic research to reveal the genetic basis of pediatric CNS tumors, as well as to define targets for the application and development of innovative therapeutics that form the basis of the upcoming era of personalized medicine.

Revealing Pan-Histology Immunomodulatory Targets in Pediatric Central Nervous System Tumors

BACKGROUND

The application of immunotherapy for pediatric CNS malignancies has been limited by the poorly understood immune landscape in this context. The aim of this study was to uncover the mechanisms of immune suppression common among pediatric brain tumors.

METHODS

We apply an immunologic clustering algorithm validated by The Cancer Genome Atlas Project to an independent pediatric CNS transcriptomic dataset. Within the clusters, the mechanisms of immunosuppression are explored via tumor microenvironment deconvolution and survival analyses to identify relevant immunosuppressive genes with translational relevance.

RESULTS

High-grade diseases fall predominantly within an immunosuppressive subtype (C4) that independently lowers overall survival time and where common immune checkpoints (e.g., PDL1, CTLA4) are less relevant. Instead, we identify several alternative immunomodulatory targets with relevance across histologic diseases. Specifically, we show how the mechanism of EZH2 inhibition to enhance tumor immunogenicity in vitro via the upregulation of MHC class 1 is applicable to a pediatric CNS oncologic context. Meanwhile, we identify that the C3 (inflammatory) immune subtype is more common in low-grade diseases and find that immune checkpoint inhibition may be an effective way to curb progression for this subset.

CONCLUSIONS

Three predominant immunologic clusters are identified across pediatric brain tumors. Among high-risk diseases, the predominant immune cluster is associated with recurrent immunomodulatory genes that influence immune infiltrate, including a subset that impacts survival across histologies.

Network-targeting combination therapy of leptomeningeal glioblastoma using multiple synthetic lethal strategies: a case report

Network targeting of disease-specific nodes represents a useful principle for designing combination cancer therapy. In this case of a patient with relapsed leptomeningeal glioblastoma, comprehensive molecular diagnosis led to the identification of a disease network characterized by multiple disease-specific synthetic lethal vulnerabilities involving DNA repair, REDOX homeostasis, and impaired autophagy which suggested a novel network-targeting combination therapy (NTCT). A treatment regimen consisting of lomustine, olaparib, digoxin, metformin, and high dose intravenous ascorbate was employed using the principle of intra-patient dose escalation to deliver the treatment with adequate safety measures to achieve a definitive clinical result.

Severe Untreated Scoliosis and Early Onset Breast Cancer in a Patient with Neurofibromatosis Associated with a Nonsense Variant of NF1 Gene

Background

Neurofibromatosis 1 (NF1) is a relatively common genetic disorder linked to skeletal abnormalities and elevated risk of cancer. Early onset scoliosis is common in patients with NF1 although severe scoliosis is rare. Scoliosis complicates the normal development and growth and may lead to thoracic insufficiency syndrome. The increased risk for breast cancer in young NF1 female patients has been recently identified.

Case Presentation

We describe a NF1 patient with dystrophic scoliosis symptoms emerged at childhood. At 37 years of age major scoliosis curve in the thoracolumbar region was 80 degrees. The patient was diagnosed with breast cancer at the age of 37 years, histologically the breast cancer was ductal, hormone receptor positive and Her2-positive.

Results

A novel pathogenic variant in NF1 p.(Trp2348*) was identified by next-generation sequencing method. The patient did not have pathogenic variants in BRCA genes or in other currently known hereditary breast cancer genes.

Conclusion

Here, we describe a novel pathogenic variant in NF1 named p.(Trp2348*) which may cause severe dystrophic scoliosis and deteriorate the quality of life and physical function, as well as Her-2 positive breast cancer. Untreated dystrophic scoliosis in patients with NF1 may result in significant spinal deformity and deteriorate the quality of life and physical function. Genetic counseling is recommended in all patients with NF1. Patients need routine follow-up throughout life. Multidisciplinary consulting is warranted in patients with neurofibromatosis 1.

Characteristics of glioblastomas and immune microenvironment in a Chinese family with Lynch syndrome and concurrent porokeratosis

Background

Lynch syndrome (LS)-associated glioblastoma (GBM) is rare in clinical practice, and simultaneous occurrence with cutaneous porokeratosis is even rarer. In this study, we analyzed the clinicopathological and genetic characteristics of LS-associated GBMs and concurrent porokeratosis, as well as evaluated the tumor immune microenvironment (TIME) of LS-associated GBMs.

Methods

Immunohistochemical staining was used to confirm the histopathological diagnosis, assess MMR and PD-1/PD-L1 status, and identify immune cell subsets. FISH was used to detect amplification of EGFR and PDGFRA, and deletion of 1p/19q and CDKN2A. Targeted NGS assay analyzed somatic variants, MSI, and TMB status, while whole-exome sequencing and Sanger sequencing were carried out to analyze the germline mutations.

Results

In the LS family, three members (I:1, II:1 and II:4) were affected by GBM. GBMs with loss of MSH2 and MSH6 expression displayed giant and multinucleated bizarre cells, along with mutations in ARID1A, TP53, ATM, and NF1 genes. All GBMs had TMB-H but not MSI-H. CD8+ T cells and CD163+ macrophages were abundant in each GBM tissue. The primary and recurrent GBMs of II:1 showed mesenchymal characteristics with high PD-L1 expression. The family members harbored a novel heterozygous germline mutation in MSH2 and FDPS genes, confirming the diagnosis of LS and disseminated superficial actinic porokeratosis.

Conclusion

LS-associated GBM exhibits heterogeneity in clinicopathologic and molecular genetic features, as well as a suppressive TIME. The presence of MMR deficiency and TMB-H may serve as predictive factors for the response to immune checkpoint inhibitor therapy in GBMs. The identification of LS-associated GBM can provide significant benefits to both patients and their family members, including accurate diagnosis, genetic counseling, and appropriate screening or surveillance protocols. Our study serves as a reminder to clinicians and pathologists to consider the possibility of concurrent genetic syndromes in individuals or families.

Mismatch Repair Deficiency and Lynch Syndrome Among Adult Patients With Glioma

PURPOSE

The Lynch syndrome (LS)-glioma association is poorly documented. As for mismatch repair deficiency (MMRd) in glioma, a hallmark of LS-associated tumors, there are only limited data available. We determined MMRd and LS prevalence in a large series of unselected gliomas, and explored the associated characteristics. Both have major implications in terms of treatment, screening, and prevention.

METHODS

Somatic next-generation sequencing was performed on 1,225 treatment-naive adult gliomas referred between 2017 and June 2022. For gliomas with ≥1 MMR pathogenic variant (PV), MMR immunohistochemistry (IHC) was done. Gliomas with ≥1 PV and protein expression loss were considered MMRd. Eligible patients had germline testing. To further explore MMRd specifically in glioblastomas, isocitrate dehydrogenase (IDH)-wild type (wt), we performed IHC, and complementary sequencing when indicated, in a series of tumors diagnosed over the 2007-2021 period.

RESULTS

Nine gliomas were MMRd (9/1,225; 0.73%). Age at glioma diagnosis was <50 years for all but one case. Eight were glioblastomas, IDH-wt, and one was an astrocytoma, IDH-mutant. ATRX (n = 5) and TP53 (n = 8) PV were common. There was no TERT promoter PV or EGFR amplification. LS prevalence was 5/1,225 (0.41%). One 77-year-old patient was a known LS case. Four cases had a novel LS diagnosis, with germline PV in MSH2 (n = 3) and MLH1 (n = 1). One additional patient had PMS2-associated constitutional mismatch repair deficiency. Germline testing was negative in three MSH6-deficient tumors. In the second series of glioblastomas, IDH-wt, MMRd prevalence was 12.5% in the <40-year age group, 2.6% in the 40-49 year age group, and 1.6% the ≥50 year age group.

CONCLUSION

Screening for MMRd and LS should be systematic in glioblastomas, IDH-wt, diagnosed under age 50 years.

Recapitulating the Key Advances in the Diagnosis and Prognosis of High-Grade Gliomas: Second Half of 2021 Update

High-grade gliomas (World Health Organization grades III and IV) are the most frequent and fatal brain tumors, with median overall survivals of 24–72 and 14–16 months, respectively. We reviewed the progress in the diagnosis and prognosis of high-grade gliomas published in the second half of 2021. A literature search was performed in PubMed using the general terms “radio* and gliom*” and a time limit from 1 July 2021 to 31 December 2021. Important advances were provided in both imaging and non-imaging diagnoses of these hard-to-treat cancers. Our prognostic capacity also increased during the second half of 2021. This review article demonstrates slow, but steady improvements, both scientifically and technically, which express an increased chance that patients with high-grade gliomas may be correctly diagnosed without invasive procedures. The prognosis of those patients strictly depends on the final results of that complex diagnostic process, with widely varying survival rates.

MYB/MYBL1::QKI fusion-positive diffuse glioma

The MYB/MYBL1::QKI fusion induces the protooncogene, MYB, and deletes the tumor suppressor gene, QKI. MYB/MYBL1::QKI rearrangement was previously reported only in angiocentric glioma (AG) and diffuse low-grade glioma. This report compares 2 tumors containing the MYB/MYBL1::QKI fusion: a diffuse pediatric-type high-grade glioma (DPedHGG) in an 11-year-old boy and an AG in a 46-year-old woman. We used immunohistochemistry, next-generation sequencing, and methylation profiling to characterize each tumor and compare our findings to the literature on AG and tumors with the MYB/MYBL1::QKI rearrangement. Both tumors were astrocytic with angiocentric patterns. The MYB::QKI fusion-positive DPedHGG, which recurred once, was accompanied by TP53 mutation and amplification of CDK6 and KRAS, suggesting malignant transformation secondary to additional genetic aberrations. The second case was the adult AG with MYBL1::QKI fusion, which mimicked ependymoma based on histopathology and its dot- and ring-like epithelial membrane antigen positivity. Combined with a literature review, our results suggest that MYB/MYBL1 alterations are not limited to low-grade gliomas, including AG. AG is most common in the cerebra of children and adolescents but exceptional cases occur in adults and the acquisition of additional genetic mutations may contribute to high-grade glioma. These cases further demonstrate that molecular characteristics, morphologic features, and clinical context are essential for diagnosis.

Pediatric brain tumors: A neuropathologist's approach to the integrated diagnosis

The classification of tumors of the central nervous system (CNS) is a rapidly evolving field. While tumors were historically classified on the basis of morphology, the recent integration of molecular information has greatly refined this process. In some instances, molecular alterations provide significant prognostic implications beyond what can be ascertained by morphologic examination alone. Additionally, tumors may harbor molecular alterations that provide a therapeutic target. Pediatric CNS tumors, in particular, rely heavily on the integration of molecular data with histologic, clinical, and radiographic features to reach the most accurate diagnosis. This review aims to provide insight into a neuropathologist's approach to the clinical workup of pediatric brain tumors with an ultimate goal of reaching an integrated diagnosis that provides the most accurate classification and informs prognosis and therapy selection. The primary focus will center on how histology and molecular findings are used in combination with clinical and radiographic information to reach a final, integrated diagnosis.

Mismatch repair protein mutations in isocitrate dehydrogenase (IDH)-mutant astrocytoma and IDH-wild-type glioblastoma

Background

Mutations in mismatch repair (MMR) genes (MSH2, MSH6, MLH1, and PMS2) are associated with microsatellite instability and a hypermutator phenotype in numerous systemic cancers, and germline MMR mutations have been implicated in multi-organ tumor syndromes. In gliomas, MMR mutations can function as an adaptive response to alkylating chemotherapy, although there are well-documented cases of germline and sporadic mutations, with detrimental effects on patient survival.

Methods

The clinical, pathologic, and molecular features of 18 IDH-mutant astrocytomas and 20 IDH-wild-type glioblastomas with MMR mutations in the primary tumor were analyzed in comparison to 361 IDH-mutant and 906 IDH-wild-type tumors without MMR mutations. In addition, 12 IDH-mutant astrocytomas and 18 IDH-wild-type glioblastomas that developed MMR mutations between initial presentation and tumor recurrence were analyzed in comparison to 50 IDH-mutant and 104 IDH-wild-type cases that remained MMR-wild-type at recurrence.

Results

In both IDH-mutant astrocytoma and IDH-wild-type glioblastoma cohorts, the presence of MMR mutation in primary tumors was associated with significantly higher tumor mutation burden (TMB) (P < .0001); however, MMR mutations only resulted in worse overall survival in the IDH-mutant astrocytomas (P = .0069). In addition, gain of MMR mutation between the primary and recurrent surgical specimen occurred more frequently with temozolomide therapy (P = .0073), and resulted in a substantial increase in TMB (P < .0001), higher grade (P = .0119), and worse post-recurrence survival (P = .0022) in the IDH-mutant astrocytoma cohort.

Conclusions

These results suggest that whether present initially or in response to therapy, MMR mutations significantly affect TMB but appear to only influence the clinical outcome in IDH-mutant astrocytoma subsets.

Imaging features associated with H3 K27-altered and H3 G34-mutant gliomas: a narrative systematic review

Background

Advances in molecular diagnostics accomplished the discovery of two malignant glioma entities harboring alterations in the H3 histone: diffuse midline glioma, H3 K27-altered and diffuse hemispheric glioma, H3 G34-mutant. Radiogenomics research, which aims to correlate tumor imaging features with genotypes, has not comprehensively examined histone-altered gliomas (HAG). The aim of this research was to synthesize the current published data on imaging features associated with HAG.

Methods

A systematic search was performed in March 2022 using PubMed and the Cochrane Library, identifying studies on the imaging features associated with H3 K27-altered and/or H3 G34-mutant gliomas.

Results

Forty-seven studies fulfilled the inclusion criteria, the majority on H3 K27-altered gliomas. Just under half (21/47) were case reports or short series, the remainder being diagnostic accuracy studies. Despite heterogeneous methodology, some themes emerged. In particular, enhancement of H3 K27M-altered gliomas is variable and can be less than expected given their highly malignant behavior. Low apparent diffusion coefficient values have been suggested as a biomarker of H3 K27-alteration, but high values do not exclude this genotype. Promising correlations between high relative cerebral blood volume values and H3 K27-alteration require further validation. Limited data on H3 G34-mutant gliomas suggest some morphologic overlap with 1p/19q-codeleted oligodendrogliomas.

Conclusions

The existing data are limited, especially for H3 G34-mutant gliomas and artificial intelligence techniques. Current evidence indicates that imaging-based predictions of HAG are insufficient to replace histological assessment. In particular, H3 K27-altered gliomas should be considered when occurring in typical midline locations irrespective of enhancement characteristics.

Chromosomal instability in adult-type diffuse gliomas

Chromosomal instability (CIN) is a fundamental property of cancer and a key underlying mechanism of tumorigenesis and malignant progression, and has been documented in a wide variety of cancers, including colorectal carcinoma with mutations in genes such as APC. Recent reports have demonstrated that CIN, driven in part by mutations in genes maintaining overall genomic stability, is found in subsets of adult-type diffusely infiltrating gliomas of all histologic and molecular grades, with resulting elevated overall copy number burden, chromothripsis, and poor clinical outcome. Still, relatively few studies have examined the effect of this process, due in part to the difficulty of routinely measuring CIN clinically. Herein, we review the underlying mechanisms of CIN, the relationship between chromosomal instability and malignancy, the prognostic significance and treatment potential in various cancers, systemic disease, and more specifically, in diffusely infiltrating glioma subtypes. While still in the early stages of discovery compared to other solid tumor types in which CIN is a known driver of malignancy, the presence of CIN as an early factor in gliomas may in part explain the ability of these tumors to develop resistance to standard therapy, while also providing a potential molecular target for future therapies.

Comprehensive development and validation of gene signature for predicting survival in patients with glioblastoma

Glioblastoma (GBM) is the most common brain tumor, with rapid proliferation and fatal invasiveness. Large-scale genetic and epigenetic profiling studies have identified targets among molecular subgroups, yet agents developed against these targets have failed in late clinical development. We obtained the genomic and clinical data of GBM patients from the Chinese Glioma Genome Atlas (CGGA) and performed the least absolute shrinkage and selection operator (LASSO) Cox analysis to establish a risk model incorporating 17 genes in the CGGA693 RNA-seq cohort. This risk model was successfully validated using the CGGA325 validation set. Based on Cox regression analysis, this risk model may be an independent indicator of clinical efficacy. We also developed a survival nomogram prediction model that combines the clinical features of OS. To determine the novel classification based on the risk model, we classified the patients into two clusters using ConsensusClusterPlus, and evaluated the tumor immune environment with ESTIMATE and CIBERSORT. We also constructed clinical traits-related and co-expression modules through WGCNA analysis. We identified eight genes (ANKRD20A4, CLOCK, CNTRL, ICA1, LARP4B, RASA2, RPS6, and SET) in the blue module and three genes (MSH2, ZBTB34, and DDX31) in the turquoise module. Based on the public website TCGA, two biomarkers were significantly associated with poorer OS. Finally, through GSCALite, we re-evaluated the prognostic value of the essential biomarkers and verified MSH2 as a hub biomarker.

Therapeutic Opportunities of Disrupting Genome Integrity in Adult Diffuse Glioma

Adult diffuse glioma, particularly glioblastoma (GBM), is a devastating tumor of the central nervous system. The existential threat of this disease requires on-going treatment to counteract tumor progression. The present outcome is discouraging as most patients will succumb to this disease. The low cure rate is consistent with the failure of first-line therapy, radiation and temozolomide (TMZ). Even with their therapeutic mechanism of action to incur lethal DNA lesions, tumor growth remains undeterred. Delivering additional treatments only delays the inescapable development of therapeutic tolerance and disease recurrence. The urgency of establishing lifelong tumor control needs to be re-examined with a greater focus on eliminating resistance. Early genomic and transcriptome studies suggest each tumor subtype possesses a unique molecular network to safeguard genome integrity. Subsequent seminal work on post-therapy tumor progression sheds light on the involvement of DNA repair as the causative contributor for hypermutation and therapeutic failure. In this review, we will provide an overview of known molecular factors that influence the engagement of different DNA repair pathways, including targetable vulnerabilities, which can be exploited for clinical benefit with the use of specific inhibitors.