Contribution of 1p, 19q, 9p and 10q Automated Analysis by FISH to the Diagnosis and Prognosis of Oligodendroglial Tumors According to WHO 2016 Guidelines

1p and/or 19q polysomy is an adverse prognostic factor in oligodendrogliomas, and easy to detect by automated FISH

OBJECTIVE

To study the feasibility of automated analysis by FISH technique in the determination of the 1p and/or 19q polysomy in oligodendrogliomas (OGs) and to explore its prognostic value.

METHODS

We analyzed a retrospective monocentric series of 145 consecutive OGs with IDH mutation and 1p/19q codeletion. For all cases, automated FISH analyses were performed to determine 1p and/or 19q polysomy status and results were compared to manual analysis to verify the concordance of the two methods. Polysomic status was then compared to clinical and histological data, the CDKN2A deletion status when available, event free survival (EFS) and overall survival (OS).

RESULTS

Our study comprised 79 grade 2 OGs (O2) and 66 grade 3 OGs (O3). Polysomy of 1p and/or 19q was observed in 58 cases (40% of whole cohort) with a significant enrichment in the high grade cohort (59% versus 24%; p < 0,0001) and recurrent cases (55%). A majority of polysomic cases were copolysomic for 1p and 19q (75% of the polysomic cohort) rather than 1p or 19q single polysomy (21% and 4% respectively). Polysomy was correlated to high grade histological criteria of high mitotic and Mib1 proliferative indices (p = 0,002 and p = 0,0005 respectively) and to vascular proliferation (p = 0,0003). Univariate and multivariate analysis showed a significant correlation betwen polysomy and a shorter EFS and OS (p = 0,02 and p = 0,016 respectively). Concordance between manual and automated analysis was almost perfect for both 1p and 19q analysis (96 and 98% respectively, κ = 0,92 and 0,95 respectively). Automated analysis revealed that the large majority of polysomic signatures are represented by a small number of R/G signals (mainly 7 signatures) allowing a very easy implementation to pre-existent FISH platforms analysis software.

CONCLUSION

1p and/ or 19q polysomy status represent a prognostic factor in OGs and can be easily determined by automated analysis. Our study supports the clinical interest to determine the polysomic status in all primitive or recurrent OGs and underline the benefits of automated analysis which offers a better archive storage and facilitates multicentric comparison.

Spatial synaptic connectivity underlies oligodendroglioma evolution and recurrence

Oligodendrogliomas are initially slow-growing brain tumors that are prone to malignant transformation despite surgery and cytotoxic therapy. Understanding of oligodendroglioma evolution and new treatments for patients have been encumbered by a paucity of patient-matched newly diagnosed and recurrent tumor samples for multiplatform analyses, and by a lack of preclinical models for interrogation of therapeutic vulnerabilities that drive oligodendroglioma growth. Here we integrate spatial and functional analyses of tumor samples and patient-derived organoid co-cultures to show that synaptic connectivity is a hallmark of oligodendroglioma evolution and recurrence. We find that patient-matched recurrent oligodendrogliomas are enriched in synaptic gene expression programs irrespective of previous therapy or histologic grade. Analyses of spatial, single-cell, and clinical data reveal epigenetic misactivation of synaptic genes that are concentrated in regions of cortical infiltration and can be used to predict eventual oligodendroglioma recurrence. To translate these findings to patients, we show that local field potentials from tumor-infiltrated cortex at the time of resection and neuronal hyperexcitability and synchrony in patient-derived organoid co-cultures are associated with oligodendroglioma proliferation and recurrence. In preclinical models, we find that neurophysiologic drugs block oligodendroglioma growth and pathologic electrophysiology. These results elucidate mechanisms underlying oligodendroglioma evolution from an indolent tumor to a fatal disease and shed light on new biomarkers and new treatments for patients.

Evaluation of ploidy and the DNA index by flow cytometry in central nervous system tumors: a review

Research on central nervous system tumors (CNSTs) has a significant impact on the diagnosis and prognosis of patients. Currently, CNSTs are classified according to the schema proposed by the World Health Organization (WHO), which considers clinical, histopathological, and molecular characteristics, highlighting the importance of tumor biology for accurate diagnosis and optimal treatment approaches. Despite these advances, assessing DNA ploidy-a marker of tumor aggressiveness-remains complex in CNSTs. This review investigates the utility of DNA index (DNAi) and DNA ploidy analysis by flow cytometry in diagnosing CNSTs and prognosing their outcomes. We systematically reviewed studies in the PubMed database from 1990 to the present using the keywords "DNA Index", "Brain", "Flow cytometry", and "Ploidy". We identified 151 studies, 36 of which met our inclusion criteria. We found considerable variation in sample sizes and methodological variation across the studies. Discrepancies between the reported DNAi and ploidy values were observed. Aneuploidy is generally associated with more aggressive tumors, although exceptions exist. Higher DNAi levels correlate with increased malignancy, notably in glioblastomas, astrocytomas, and meningiomas, whereas diploid astrocytomas and oligodendrogliomas are associated with shorter survival rates. DNA ploidy assessment via flow cytometry could predict CNST behavior, yet methodological issues with tissue selection, adequate control samples, and technique variability remain. DNAi and ploidy assessments show promise as prognostic markers in CNSTs. However, the standardization of flow cytometry protocols and alignment with the current WHO classification schema are essential steps to integrate ploidy analysis in routine CNST assessment.

The biological significance of tumor grade, age, enhancement, and extent of resection in IDH-mutant gliomas: How should they inform treatment decisions in the era of IDH inhibitors?

The 2016 and 2021 World Health Organization 2021 Classification of central nervous system tumors have resulted in a major improvement in the classification of isocitrate dehydrogenase (IDH)-mutant gliomas. With more effective treatments many patients experience prolonged survival. However, treatment guidelines are often still based on information from historical series comprising both patients with IDH wild-type and IDH-mutant tumors. They provide recommendations for radiotherapy and chemotherapy for so-called high-risk patients, usually based on residual tumor after surgery and age over 40. More up-to-date studies give a better insight into clinical, radiological, and molecular factors associated with the outcome of patients with IDH-mutant glioma. These insights should be used today for risk stratification and for treatment decisions. In many patients with IDH-mutant grades 2 and 3 glioma, if carefully monitored postponing radiotherapy and chemotherapy is safe, and will not jeopardize the overall outcome of patients. With the INDIGO trial showing patient benefit from the IDH inhibitor vorasidenib, there is a sizable population in which it seems reasonable to try this class of agents before recommending radio-chemotherapy with its delayed adverse event profile affecting quality of survival. Ongoing trials should help to further identify the patients that are benefiting from this treatment.

Oligodendroglial tumours: subventricular zone involvement and seizure history are associated with CIC mutation status

BACKGROUND

CIC-mutant oligodendroglial tumours linked to better prognosis. We aim to investigate associations between CIC gene mutation status, MR characteristics and clinical features.

METHODS

Imaging and genomic data from the Cancer Genome Atlas and the Cancer Imaging Archive (TCGA/TCIA) for 59 patients with oligodendroglial tumours were used. Differences between CIC mutation and CIC wild-type were tested using Chi-square test and binary logistic regression analysis.

RESULTS

In univariate analysis, the clinical variables and MR features, which consisted 3 selected features (subventricular zone[SVZ] involvement, volume and seizure history) were associated with CIC mutation status (all p < 0.05). A multivariate logistic regression analysis identified that seizure history (no vs. yes odd ratio [OR]: 28.960, 95 confidence interval [CI]:2.625-319.49, p = 0.006) and SVZ involvement (SVZ- vs. SVZ+ OR: 77.092, p = 0.003; 95% CI: 4.578-1298.334) were associated with a higher incidence of CIC mutation status. The nomogram showed good discrimination, with a C-index of 0.906 (95% CI: 0.812-1.000) and was well calibrated. SVZ- group has increased (SVZ- vs. SVZ+, hazard ratio [HR]: 4.500, p = 0.04; 95% CI: 1.069-18.945) overall survival.

CONCLUSIONS

Absence of seizure history and SVZ involvement (-) was associated with a higher incidence of CIC mutation.

Genomic analysis reveals secondary glioblastoma after radiotherapy in a subset of recurrent medulloblastomas

Despite great advances in understanding of molecular pathogenesis and achievement of a high cure rate in medulloblastoma, recurrent medulloblastomas are still dismal. Additionally, misidentification of secondary malignancies due to histological ambiguity leads to misdiagnosis and eventually to inappropriate treatment. Nevertheless, the genomic characteristics of recurrent medulloblastomas are poorly understood, largely due to a lack of matched primary and recurrent tumor tissues. We performed a genomic analysis of recurrent tumors from 17 pediatric medulloblastoma patients. Whole transcriptome sequencing revealed that a subset of recurrent tumors initially diagnosed as locally recurrent medulloblastomas are secondary glioblastomas after radiotherapy, showing high similarity to the non-G-CIMP proneural subtype of glioblastoma. Further analysis, including whole exome sequencing, revealed missense mutations or complex gene fusion events in PDGFRA with augmented expression in the secondary glioblastomas after radiotherapy, implicating PDGFRA as a putative driver in the development of secondary glioblastomas after treatment exposure. This result provides insight into the possible application of PDGFRA-targeted therapy in these second malignancies. Furthermore, genomic alterations of TP53 including 17p loss or germline/somatic mutations were also found in most of the secondary glioblastomas after radiotherapy, indicating a crucial role of TP53 alteration in the process. On the other hand, analysis of recurrent medulloblastomas revealed that the most prevalent alterations are the loss of 17p region including TP53 and gain of 7q region containing EZH2 which already exist in primary tumors. The 7q gain events are frequently accompanied by high expression levels of EZH2 in both primary and recurrent medulloblastomas, which provides a clue to a new therapeutic target to prevent recurrence. Considering the fact that it is often challenging to differentiate between recurrent medulloblastomas and secondary glioblastomas after radiotherapy, our findings have major clinical implications both for correct diagnosis and for potential therapeutic interventions in these devastating diseases.

Impact of 9p deletion and p16, Cyclin D1, and Myc hyperexpression on the outcome of anaplastic oligodendrogliomas

Objective

To study the presence of 9p deletion and p16, cyclin D1 and Myc expression and their respective diagnostic and prognostic interest in oligodendrogliomas.

Methods

We analyzed a retrospective series of 40 consecutive anaplastic oligodendrogliomas (OIII) from a single institution and compared them to a control series of 10 low grade oligodendrogliomas (OII). Automated FISH analysis of chromosome 9p status and immunohistochemistry for p16, cyclin D1 and Myc was performed for all cases and correlated with clinical and histological data, event free survival (EFS) and overall survival (OS).

Results

Chromosome 9p deletion was observed in 55% of OIII (22/40) but not in OII. Deletion was highly correlated to EFS (median = 29 versus 53 months, p<0.0001) and OS (median = 48 versus 83 months, p<0.0001) in both the total cohort and the OIII population. In 9p non-deleted oligodendrogliomas, p16 hyperexpression correlated with a shorter OS (p = 0.02 in OII and p = 0.0001 in OIII) whereas lack of p16 expression was correlated to a shorter EFS and OS in 9p deleted OIII (p = 0.001 and p = 0.0002 respectively). Expression of Cyclin D1 was significantly higher in OIII (median expression 45% versus 14% for OII, p = 0.0006) and was correlated with MIB-1 expression (p<0.0001), vascular proliferation (p = 0.002), tumor necrosis (p = 0.04) and a shorter EFS in the total cohort (p = 0.05). Hyperexpression of Myc was correlated to grade (median expression 27% in OII versus 35% in OIII, p = 0.03), and to a shorter EFS in 9p non-deleted OIII (p = 0.01).

Conclusion

Chromosome 9p deletion identifies a subset of OIII with significantly worse prognosis. The combination of 9p status and p16 expression level identifies two distinct OIII populations with divergent prognosis. Hyperexpression of Bcl1 and Myc appears highly linked to anaplasia but the prognostic value is unclear and should be investigated further.

A Comparative Review of Demographics, Incidence, and Epidemiology of Histologically Confirmed Intracranial Tumors in Brazil and Bulgaria

Intracranial tumors (ICTs) attract numerous scientific teams and tremendous financial resources worldwide. These lesions of the central nervous system (CNS) can be both benign and malignant in biological behavior as well as local or metastatic in origin. We compared data from two studies on primary and metastatic ICTs from Brazil and Bulgaria, based on histopathologically confirmed ICTs from tertiary health centers. Primary ICTs significantly outweigh the frequency of metastatic ICTs. Primary ICTs represent 86.45% in Brazil and 69.17% in Bulgaria, with around 60% of their totals being malignant. There is a statistical dominance of tumors from the neuroepithelial origin, with the most common entry being glioblastoma multiforme. The second-most common primary ICT group comprises tumors of meningeal origin. Metastatic ICTs show great variance; 13.55% in Brazil and 31.38% in Bulgaria of all ICT cases being attributed to them. However, metastatic ICTs are even a more diverse group than neuroepithelial tumors, with the majority of this group comprising metastatic colorectal adenocarcinoma (almost exclusively in males), metastatic breast adenocarcinoma in females, metastatic pulmonary carcinomas (primarily from the non-small cell group with a male predominance), and metastatic melanoma with an even gender ratio.