A threshold for mitotic activity and post-surgical residual volume defines distinct prognostic groups for astrocytoma IDH-mutant.

AIMS: The distinction between CNS WHO grade 2 and grade 3 is instrumental in choosing between observational follow-up and adjuvant treatment for resected astrocytomas IDH-mutant. However, the criteria of CNS WHO grade 2 vs 3 have not been updated since the pre-IDH era. METHODS: Maximal mitotic activity in consecutive high-power fields corresponding to 3 mm2 was examined for 118 lower-grade astrocytomas IDH-mutant. The prognostic value for time-to-treatment (TTT) and overall survival (OS) of mitotic activity and other putative prognostic factors (including age, performance status, pre-surgical tumour volume, multilobar involvement, post-surgical residual tumour volume and midline involvement) was assessed for tumours with ATRX loss and the absence of CDKN2A homozygous deletion or CDK4 amplification, contrast enhancement, histological necrosis and microvascular proliferation. RESULTS: Seventy-one per cent of the samples had <6 mitoses per 3 mm2 . Mitotic activity, residual volume and multilobar involvement were independent prognostic factors of TTT. The threshold of ≥6 mitoses per 3 mm2 identified patients with a shorter TTT (median 18.5 months). A residual volume ≥1 cm3 also identified patients with a shorter TTT (median 24.5 months). The group defined by <6 mitoses per 3 mm2 and a residual volume <1 cm3 had the longest TTT (median 73 months) and OS (100% survival at 7 years). These findings were confirmed in a validation cohort of 52 tumours. CONCLUSIONS: Mitotic activity and post-surgical residual volume can be combined to evaluate the prognosis for patients with resected astrocytomas IDH-mutant. Patients with <6 mitoses per 3 mm2 and a residual volume <1 cm3 were the best candidates for observational follow-up.

T2-Fluid-attenuated inversion recovery (FLAIR) pseudoprogression in patients with anaplastic oligodendrogliomas treated with procarbazine, lomustine and vincristine (PCV) chemotherapy alone.

BACKGROUND: Pseudoprogression in gliomas has been extensively described after radiotherapy with or without chemotherapy, but not after chemotherapy alone. Here we describe the occurrence of pseudoprogression in patients with anaplastic oligodendrogliomas treated with postoperative procarbazine, lomustine and vincristine (PCV) chemotherapy alone. METHODS: We retrospectively reviewed the medical and radiological files of patients with 1p/19q codeleted, IDH-mutant anaplastic oligodendrogliomas treated with PCV chemotherapy alone who presented magnetic resonance imaging (MRI) modifications suggestive of tumour progression and in whom the final diagnosis was a pseudoprogression. RESULTS: We identified six patients. All patients underwent a surgical resection and were treated with PCV chemotherapy without radiotherapy. After a median of 11 months following the initiation of chemotherapy (range: 3-49 months), the patients developed asymptomatic white matter MRI modifications around the surgical cavity leading to the suspicion of a tumour progression. These modifications appeared as hyperintense on T2-fluid-attenuated inversion recovery (FLAIR) sequence, hypointense on T1 sequence, and lacked mass effect (0/6), contrast enhancement (0/6), restriction on diffusion-weighted imaging (0/4), relative cerebral blood volume (rCBV) increase on perfusion MRI (0/4), and hypermetabolism on 18 F-fluoro-L-dopa positron emission tomography (18 F-DOPA PET) scan (0/3). One patient underwent a surgical resection demonstrating no tumour recurrence; the five other patients were considered as having post-therapeutic modifications based on imaging characteristics. After a median follow-up of 4 years all patients were progression-free. CONCLUSIONS: Anaplastic oligodendroglioma patients treated with postoperative PCV chemotherapy alone occasionally develop T2/FLAIR hyperintensities around the surgical cavity that can wrongly suggest tumour progression. Multimodal imaging and close follow-up should be considered in this situation.

Characteristics of Anaplastic Oligodendrogliomas Short-Term Survivors: A POLA Network Study.

BACKGROUND: Anaplastic oligodendrogliomas IDH-mutant and 1p/19q codeleted (AO) occasionally have a poor outcome. Herein we aimed at analyzing their characteristics. METHODS: We retrospectively analyzed the characteristics of 44 AO patients with a cancer-specific survival <5 years (short-term survivors, STS) and compared them with those of 146 AO patients with a survival ≥5 years (classical survivors, CS) included in the POLA network. RESULTS: Compared to CS, STS were older (P = .0001), less frequently presented with isolated seizures (P < .0001), more frequently presented with cognitive dysfunction (P < .0001), had larger tumors (P = .= .003), a higher proliferative index (P = .= .0003), and a higher number of chromosomal arm abnormalities (P = .= .02). Regarding treatment, STS less frequently underwent a surgical resection than CS (P = .= .0001) and were more frequently treated with chemotherapy alone (P = .= .009) or with radiotherapy plus temozolomide (P = .= .05). Characteristics independently associated with STS in multivariate analysis were cognitive dysfunction, a number of mitosis > 8, and the absence of tumor resection. Based on cognitive dysfunction, type of surgery, and number of mitosis, patients could be classified into groups of standard (18%) and high (62%) risk of <5 year survival. CONCLUSION: The present study suggests that although STS poor outcome appears to largely result from a more advanced disease at diagnosis, surgical resection may be particularly important in this population.

Radiotherapy Plus Procarbazine, Lomustine, and Vincristine Versus Radiotherapy Plus Temozolomide for IDH-Mutant Anaplastic Astrocytoma: A Retrospective Multicenter Analysis of the French POLA Cohort.

BACKGROUND: IDH-mutant anaplastic astrocytomas (AAs) are chemosensitive tumors for which the best choice of adjuvant chemotherapy between procarbazine, lomustine, and vincristine (PCV) or temozolomide (TMZ) after radiotherapy (RT) remains unclear. METHODS: In a large cohort of patients with histologically proven 2016 World Health Organization classification AA with IDH1/2 mutations included in the French national POLA cohort (n = 355), the primary objective was to compare progression-free survival (PFS) between the two treatment regimens (n = 311). Secondary endpoints were overall survival (OS), progression type, pseudoprogression rate, and toxicity. RESULTS: The 4-year PFS in the RT + PCV arm was 70.8% versus 53.5% in the RT + TMZ arm, with a hazard ratio (HR) of 0.58 (95% confidence interval [CI], 0.38-0.87; p = .0074) in univariable analysis and 0.63 (95% CI, 0.41-0.97; p = .0348) in multivariable analysis. The 4-year OS in the RT + PCV arm was 84.3% versus 76.6% in the RT + TMZ arm, with an HR of 0.57 (95% CI, 0.30-1.05; p = .0675) in univariable analysis. Toxicity was significantly higher in the RT + PCV arm with more grade ≥3 toxicity (46.7% vs. 8.6%, p < .0001). CONCLUSION: RT + PCV significantly improved PFS compared with RT + TMZ for IDH-mutant AA. However, RT + TMZ was better tolerated. IMPLICATIONS FOR PRACTICE: In the absence of fully conducted randomized trials comparing procarbazine, lomustine, and vincristine (PCV) with temozolomide (TMZ) in adjuvant treatment after radiotherapy (RT) for the management of IDH-mutant anaplastic astrocytoma (AA) and a similar level of evidence, these two chemotherapies are both equally recommended in international guidelines. This study in a national cohort of IDH-mutant AA defined according the 2016 World Health Organization (WHO) classification shows for the first time that the RT + PCV regimen significantly improves progression-free survival in comparison with the RT + TMZ regimen. Even if at the time of analysis the difference in overall survival was not significant, this result provides new evidence for the debate about the chemotherapy regimen to prescribe in adjuvant treatment to RT for WHO 2016 IDH-mutant AA.

Prognostic impact of the 2016 WHO classification of diffuse gliomas in the French POLA cohort.

The new WHO classification of diffuse gliomas has been refined and now includes the 1p/19q codeletion, IDH1/2 mutation, and histone H3-K27M mutation. Our objective was to assess the prognostic value of the updated 2016 WHO classification in the French POLA cohort. All cases of high-grade oligodendroglial tumors sent for central pathological review and included into the French nationwide POLA cohort were reclassified according to the updated 4th WHO classification. In total, 1041 patients were included, with a median age at diagnosis of 50.4 years (range 17.1-84.4). Based on the new histomolecular classification, diagnoses included anaplastic oligodendroglioma IDH mutant and 1p/19q-codeleted (32.5 %), anaplastic astrocytoma IDH mutant (IDH (mut)) (11.0 %), anaplastic astrocytoma IDH wild type (IDH (wt)) (5.3 %), glioblastoma IDH (mut) (17.1 %), and glioblastoma IDH (wt) (33.2 %). Ten patients presented with a diffuse midline tumor, H3 K27M mutant. The new WHO classification was prognostic for progression-free survival (PFS) and overall survival (OS) (p < 0.001). We did not find prognosis differences between grades III and IV for IDH (mut) 1p/19q intact and IDH (wt) gliomas in univariate and multivariate analyses. Among anaplastic astrocytoma IDH (wt), cases with chromosome arm 7p gain and 10q loss (55 %) had shorter PFS than the others (p = 0.027). In conclusion, the new WHO histomolecular classification of diffuse gliomas presented with high prognostic value. Grading was not discriminant between grade III and IV high-grade gliomas.

[Improving the management of rare brain cancers with the POLA network]. / Améliorer la prise en charge des cancers rares du cerveau avec le réseau POLA.

The national POLA network is dedicated to the management of certain rare brain tumours, mainly anaplastic oligodendrogliomas, anaplastic oligoastrocytomas and glioblastomas with oligodendroglioma component. The nursing team and the patient are at the heart of the organisation.

REVOLUMAB: A phase II trial of nivolumab in recurrent IDH mutant high-grade gliomas.

BACKGROUND: Novel effective treatments are needed for recurrent IDH mutant high-grade gliomas (IDHm HGGs). The aim of the multicentric, single-arm, phase II REVOLUMAB trial (NCT03925246) was to assess the efficacy and safety of the anti-PD1 Nivolumab in patients with recurrent IDHm HGGs. PATIENTS AND METHODS: Adult patients with IDHm WHO grade 3-4 gliomas recurring after radiotherapy and ≥ 1 line of alkylating chemotherapy were treated with intravenous Nivolumab until end of treatment (12 months), progression, unacceptable toxicity, or death. The primary endpoint was the 24-week progression-free survival rate (24w-PFS) according to RANO criteria. RESULTS: From July 2019 to June 2020, 39 patients with recurrent IDHm HGGs (twenty-one grade 3, thirteen grade 4, five grade 2 with radiological evidence of anaplastic transformation; 39% 1p/19q codeleted) were enrolled. Median time since diagnosis was 5.7 years, and the median number of previous systemic treatments was two. The 24w-PFS was 28.2% (11/39, CI95% 15-44.9%). Median PFS and OS were 1.84 (CI95% 1.81-5.89) and 14.7 months (CI95% 9.18-NR), respectively. Four patients (10.3%) achieved partial response according to RANO criteria. There were no significant differences in clinical or histomolecular features between responders and non-responders. The safety profile of Nivolumab was consistent with prior studies. CONCLUSIONS: We report the results of the first trial of immune checkpoint inhibitors in IDHm gliomas. Nivolumab failed to achieve its primary endpoint. However, treatment was well tolerated, and long-lasting responses were observed in a subset of patients, supporting further evaluation in combination with other agents (e.g. IDH inhibitors).

Chromosome 7p11.2 (EGFR) variation influences glioma risk.

While gliomas are the most common primary brain tumors, their etiology is largely unknown. To identify novel risk loci for glioma, we conducted genome-wide association (GWA) analysis of two case-control series from France and Germany (2269 cases and 2500 controls). Pooling these data with previously reported UK and US GWA studies provided data on 4147 glioma cases and 7435 controls genotyped for 424 460 common tagging single-nucleotide polymorphisms. Using these data, we demonstrate two statistically independent associations between glioma and rs11979158 and rs2252586, at 7p11.2 which encompasses the EGFR gene (population-corrected statistics, P(c) = 7.72 × 10(-8) and 2.09 × 10(-8), respectively). Both associations were independent of tumor subtype, and were independent of EGFR amplification, p16INK4a deletion and IDH1 mutation status in tumors; compatible with driver effects of the variants on glioma development. These findings show that variation in 7p11.2 is a determinant of inherited glioma risk.

Cellular senescence in malignant cells promotes tumor progression in mouse and patient Glioblastoma.

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults, yet it remains refractory to systemic therapy. Elimination of senescent cells has emerged as a promising new treatment approach against cancer. Here, we investigated the contribution of senescent cells to GBM progression. Senescent cells are identified in patient and mouse GBMs. Partial removal of p16Ink4a-expressing malignant senescent cells, which make up less than 7 % of the tumor, modifies the tumor ecosystem and improves the survival of GBM-bearing female mice. By combining single cell and bulk RNA sequencing, immunohistochemistry and genetic knockdowns, we identify the NRF2 transcription factor as a determinant of the senescent phenotype. Remarkably, our mouse senescent transcriptional signature and underlying mechanisms of senescence are conserved in patient GBMs, in whom higher senescence scores correlate with shorter survival times. These findings suggest that senolytic drug therapy may be a beneficial adjuvant therapy for patients with GBM.

Incidence and characteristics of pseudoprogression in IDH-mutant high-grade gliomas: A POLA network study.

BACKGROUND: Incidence and characteristics of pseudoprogression in isocitrate dehydrogenase-mutant high-grade gliomas (IDHmt HGG) remain to be specifically described. METHODS: We analyzed pseudoprogression characteristics and explored the possibility of pseudoprogression misdiagnosis in IDHmt HGG patients, treated with radiotherapy (RT) (with or without chemotherapy [CT]), included in the French POLA network. Pseudoprogression was analyzed in patients with MRI available for review (reference cohort, n = 200). Pseudoprogression misdiagnosis was estimated in this cohort and in an independent cohort (control cohort, n = 543) based on progression-free survival before and after first progression. RESULTS: In the reference cohort, 38 patients (19%) presented a pseudoprogression after a median time of 10.5 months after RT. Pseudoprogression characteristics were similar across IDHmt HGG subtypes. In most patients, it consisted of the appearance of one or several infracentimetric, asymptomatic, contrast-enhanced lesions occurring within 2 years after RT. The only factor associated with pseudoprogression occurrence was adjuvant PCV CT. Among patients considered as having a first true progression, 7 out of 41 (17%) in the reference cohort and 35 out of 203 (17%) in the control cohort were retrospectively suspected to have a misdiagnosed pseudoprogression. Patients with a misdiagnosed pseudoprogression were characterized by a time to event and an outcome similar to that of patients with a pseudoprogression but presented with larger and more symptomatic lesions. CONCLUSION: In patients with an IDHmt HGG, pseudoprogression occurs later than in IDH-wildtype glioblastomas and seems not only frequent but also frequently misdiagnosed. Within the first 2 years after RT, the possibility of a pseudoprogression should be carefully considered.

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.

Comparative assessment of 5 methods (methylation-specific polymerase chain reaction, MethyLight, pyrosequencing, methylation-sensitive high-resolution melting, and immunohistochemistry) to analyze O6-methylguanine-DNA-methyltranferase in a series of 100 glioblastoma patients.

BACKGROUND: There is a strong need to determine the best technique for O(6) -methylguanine-DNA-methyltranferase (MGMT) analysis, because MGMT status is currently used in clinical trials and occasionally in routine clinical practice for glioblastoma patients. METHODS: The authors compared analytical performances and predictive values of 5 techniques in a series of 100 glioblastoma patients who received standard of care treatment (Stupp protocol). RESULTS: MGMT promoter was considered methylated in 33%, 33%, 42%, and 60% of patients by methylation-sensitive high-resolution melting, MethyLight, pyrosequencing (with an optimal risk cutoff at 8% for the average percentage of the 5 CpGs tested), and methylation-specific polymerase chain reaction (MS-PCR), respectively. Fifty-nine percent of the samples had <23% (the optimal risk cutoff) of MGMT-positive tumor cells. The best predictive values for overall survival (OS), after adjustment for age and performance status, were obtained by pyrosequencing (hazard ratio [HR], 0.32; P < .0001), MS-PCR (HR, 0.37; P < .0001), and immunohistochemistry (HR, 0.43; P = .0005) as compared with methylation-sensitive high-resolution melting (HR, 0.52 P = .02) and MethyLight (HR, 0.6; P = .05). For progression-free survival (PFS), the best predictive values were obtained with pyrosequencing (HR, 0.35; P < .0001), methylation-sensitive high-resolution melting (HR, 0.46; P = .002), and MS-PCR (HR, 0.49; P = .002). Combining pyrosequencing and immunohistochemistry slightly improved predictive power for OS, but not for PFS. Poor reproducibility and interobserver variability were, however, observed for immunohistochemistry. CONCLUSIONS: Good prediction of survival in addition to high reproducibility and sensitivity made pyrosequencing the best among the 5 techniques tested in this study.

Identification of growth hormone receptor as a relevant target for precision medicine in low-EGFR expressing glioblastoma.

OBJECTIVE: New therapeutic approaches are needed to improve the prognosis of glioblastoma (GBM) patients. METHODS: With the objective of identifying alternative oncogenic mechanisms to abnormally activated epidermal growth factor receptor (EGFR) signalling, one of the most common oncogenic mechanisms in GBM, we performed a comparative analysis of gene expression profiles in a series of 54 human GBM samples. We then conducted gain of function as well as genetic and pharmocological inhibition assays in GBM patient-derived cell lines to functionnally validate our finding. RESULTS: We identified that growth hormone receptor (GHR) signalling defines a distinct molecular subset of GBMs devoid of EGFR overexpression. GHR overexpression was detected in one third of patients and was associated with low levels of suppressor of cytokine signalling 2 (SOCS2) expression due to SOCS2 promoter hypermethylation. In GBM patient-derived cell lines, GHR signalling modulates the expression of proteins involved in cellular movement, promotes cell migration, invasion and proliferation in vitro and promotes tumourigenesis, tumour growth, and tumour invasion in vivo. GHR genetic and pharmacological inhibition reduced cell proliferation and migration in vitro. CONCLUSION: This study pioneers a new field of investigation to improve the prognosis of GBM patients.

Up-front temozolomide in elderly patients with anaplastic oligodendroglioma and oligoastrocytoma.

Optimal treatment of anaplastic oligodendroglial tumors (AOT) in elderly patients is debatable. We report a retrospective study of 44 consecutive patients aged 70 years or older [median age: 74 years; median Karnofsky performance status (KPS): 70] treated with up-front chemotherapy using temozolomide (TMZ) at conventional doses until tumor progression. O(6)-methylguanine-DNA methyltransferase promoter (MGMTP) methylation was assessed in 38 patients. Of the 41 evaluable patients, partial response (PR) was seen in 13 (32%) patients, 17 (41%) patients achieved stable disease, while the disease progressed in 11 (27%) patients. Median progression-free survival (PFS) and overall survival (OS) were 6.9 and 12.4 months, respectively. Hematotoxicity grades 3-4 occurred in nine patients (20%). MGMTP was methylated in 50% of patients and was associated with both longer PFS (8.7 versus 5.7 months, P = 0.01) and longer OS (16.1 versus 12.4 months, P = 0.05). The rate of responders to chemotherapy was similar in MGMTP-methylated (38%) and in MGMTP-unmethylated patients (31%), but duration of response was significantly longer in responders with methylated MGMTP than in responders with unmethylated MGMTP (16.1 versus 9.6 months, P = 0.0004). This study demonstrates that a substantial number of elderly patients with AOT can achieve prolonged survival with up-front chemotherapy using TMZ. Further investigation is needed to determine whether this treatment is preferable to initial radiation therapy.

Genomic aberrations associated with outcome in anaplastic oligodendroglial tumors treated within the EORTC phase III trial 26951.

Despite similar morphological aspects, anaplastic oligodendroglial tumors (AOTs) form a heterogeneous clinical subgroup of gliomas. The chromosome arms 1p/19q codeletion has been shown to be a relevant biomarker in AOTs and to be perfectly exclusive from EGFR amplification in gliomas. To identify new genomic regions associated with prognosis, 60 AOTs from the EORTC trial 26951 were analyzed retrospectively using BAC-array-based comparative genomic hybridization. The data were processed using a binary tree method. Thirty-three BACs with prognostic value were identified distinguishing four genomic subgroups of AOTs with different prognosis (p < 0.0001). Type I tumors (25%) were characterized by: (1) an EGFR amplification, (2) a poor prognosis, (3) a higher rate of necrosis, and (4) an older age of patients. Type II tumors (21.7%) had: (1) loss of prognostic BACs located on 1p tightly associated with 19q deletion, (2) a longer survival, (3) an oligodendroglioma phenotype, and (4) a frontal location in brain. Type III AOTs (11.7%) exhibited: (1) a deletion of prognostic BACs located on 21q, and (2) a short survival. Finally, type IV tumors (41.7%) had different genomic patterns and prognosis than type I, II and III AOTs. Multivariate analysis showed that genomic type provides additional prognostic data to clinical, imaging and pathological features. Similar results were obtained in the cohort of 45 centrally reviewed-validated cases of AOTs. Whole genome analysis appears useful to screen the numerous genomic abnormalities observed in AOTs and to propose new biomarkers particularly in the non-1p/19q codeleted AOTs.

Ki-67 and MCM6 labeling indices are correlated with overall survival in anaplastic oligodendroglioma, IDH1-mutant and 1p/19q-codeleted: a multicenter study from the French POLA network.

Anaplastic oligodendroglioma (AO), IDH-mutant and 1p/19q codeleted (IDHmut+/1p19qcodel), is a high-grade glioma with only limited prognostic markers. The primary objective of this study was to evaluate, by immunohistochemistry, the prognostic value of two proliferation markers, MCM6 and Ki-67, in a large series of IDHmut+/1p19qcodel AO included in the POLA ("Prise en charge des Oligodendrogliomes Anaplasiques") French national multicenter network. We additionally examined the transcriptome obtained from this series to understand the functional pathways dysregulated with the mRNA overexpression of these two markers. The labeling indices (LI) of MCM6 and Ki-67 were obtained via computer-assisted color image analyses on immunostained AO tissues of the cohort (n = 220). Furthermore, a subgroup of AO (n = 68/220) was used to perform transcriptomic analyses. A high LI of either MCM6 (≥50%) or Ki-67 (≥15%) correlated with shorter overall survival, both in univariate (P = 0.013 and P = 0.004, respectively) and multivariate analyses (P = 0.027; multivariate Cox model including age, mitotic index, MCM6 and Ki-67). MCM6 and Ki-67 LI also correlated with overall survival in an additional retrospective cohort of 30 grade II IDHmut+/1p19qcodel oligodendrogliomas. The prognostic value of MCM6 mRNA level was confirmed in The Cancer Genome Atlas (TCGA) IDHmut+/1p19qcodel gliomas. The transcriptomic approach revealed that high transcriptional expressions of MCM6 and MKI67 were both linked positively with cell cycle progression, DNA replication, mitosis, pro-neural phenotype as well as neurogenesis, and negatively with microglial cell activation, immune response, positive regulation of myelination, oligodendrocyte development, beta-amyloid binding and postsynaptic specialization. In conclusion, the overexpression of MCM6 and/or Ki-67 is independently associated to shorter overall survival in IDHmut+/1p19qcodel AO. These two easy-to-use and cost-effective markers could thus be used concurrently in routine pathology practice. Additionally, the transcriptomic analyses showed that AO with high proliferation index have down-regulated immune response and lower microglial cells activation, and bears pro-neural phenotype.

CDKN2A homozygous deletion is a strong adverse prognosis factor in diffuse malignant IDH-mutant gliomas.

BACKGROUND: The 2016 World Health Organization (WHO) classification of central nervous system tumors stratifies isocitrate dehydrogenase (IDH)-mutant gliomas into 2 major groups depending on the presence or absence of 1p/19q codeletion. However, the grading system remains unchanged and it is now controversial whether it can be still applied to this updated molecular classification. METHODS: In a large cohort of 911 high-grade IDH-mutant gliomas from the French national POLA network (including 428 IDH-mutant gliomas without 1p/19q codeletion and 483 anaplastic oligodendrogliomas, IDH-mutant and 1p/19q codeleted), we investigated the prognostic value of the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene homozygous deletion as well as WHO grading criteria (mitoses, microvascular proliferation, and necrosis). In addition, we searched for other retinoblastoma pathway gene alterations (CDK4 amplification and RB1 homozygous deletion) in a subset of patients. CDKN2A homozygous deletion was also searched in an independent series of 40 grade II IDH-mutant gliomas. RESULTS: CDKN2A homozygous deletion was associated with dismal outcome among IDH-mutant gliomas lacking 1p/19q codeletion (P < 0.0001 for progression-free survival and P = 0.004 for overall survival) as well as among anaplastic oligodendrogliomas, IDH-mutant + 1p/19q codeleted (P = 0.002 for progression-free survival and P < 0.0001 for overall survival) in univariate and multivariate analysis including age, extent of surgery, adjuvant treatment, microvascular proliferation, and necrosis. In both groups, the presence of microvascular proliferation and/or necrosis remained of prognostic value only in cases lacking CDKN2A homozygous deletion. CDKN2A homozygous deletion was not recorded in grade II gliomas. CONCLUSIONS: Our study pointed out the utmost relevance of CDKN2A homozygous deletion as an adverse prognostic factor in the 2 broad categories of IDH-mutant gliomas stratified on 1p/19q codeletion and suggests that the grading of these tumors should be refined.

The level of activity of the alternative lengthening of telomeres correlates with patient age in IDH-mutant ATRX-loss-of-expression anaplastic astrocytomas.

All cancer cells need to maintain functional telomeres to sustain continuous cell division and proliferation. In human diffuse gliomas, functional telomeres are maintained due either to reactivation of telomerase expression, the main pathway in most cancer types, or to activation of a mechanism called the alternative lengthening of telomeres (ALT). The presence of IDH1/2 mutations (IDH-mutant) together with loss of ATRX expression (ATRX-lost) are frequently associated with ALT in diffuse gliomas. However, detection of ALT, and a fortiori its quantification, are rarely, if ever, measured in neuropathology laboratories. We measured the level of ALT activity using the previously described quantitative "C-circle" assay and analyzed it in a well characterized cohort of 104 IDH-mutant and ATRX-lost adult diffuse gliomas. We report that in IDH-mutant ATRX-lost anaplastic astrocytomas, the intensity of ALT was inversely correlated with age (p < 0.001), the younger the patient, the higher the intensity of ALT. Strikingly, glioblastomas having progressed from anaplastic astrocytomas did not exhibit this correlation. ALT activity level in the tumor did not depend on telomere length in healthy tissue cells from the same patient. In summary, we have uncovered the existence, in anaplastic astrocytomas but not in glioblastomas with the same IDH and ATRX mutations, of a correlation between patient age and the level of activity of ALT, a telomerase-independent pathway of telomere maintenance.

Gene amplification is a poor prognostic factor in anaplastic oligodendrogliomas.

Various gene amplifications have been observed in gliomas. Prognostic-genomic correlations testing simultaneously all these amplified genes have never been conducted in anaplastic oligodendrogliomas. A set of 38 genes that have been reported to be amplified in gliomas and investigated as the main targets of amplicons were studied in a series of 52 anaplastic oligodendrogliomas using bacterial artificial chromosome-array based comparative genomic hybridization and quantitative polymerase chain reaction. Among the 38 target genes, 15 were found to be amplified in at least one tumor. Overall, 27% of anaplastic oligodendrogliomas exhibited at least one gene amplification. The most frequently amplified genes were epidermal growth factor receptor (EGFR) and cyclin-dependent kinase 4/sarcoma amplified sequence (CDK4/SAS) in 17% and 8% of anaplastic oligodendrogliomas, respectively. Gene amplification and codeletion of chromosome arms 1p/19q were perfectly exclusive (p = 0.005). In uni- and multivariate analyses, gene amplification was a negative prognostic factor for progression-free survival and overall survival in anaplastic oligodendrogliomas, providing complementary information to the classic prognostic factors identified in anaplastic oligodendrogliomas (extent of surgery, KPS, and chromosome arms 1p/19q status).

Influence of MDM2 SNP309 alone or in combination with the TP53 R72P polymorphism in oligodendroglial tumors.

The transcription factor p53 and its negative regulator MDM2 are pivotal in normal and cancer cells biology. Recently, a functional single-nucleotide polymorphism in the promoter region of MDM2 (MDM2 SNP309), alone or in combination with TP53 R72P, was shown to be associated with the risk, prognosis, age at onset, molecular markers, and response to chemotherapy of various cancers. This SNP has never been specifically investigated in a large series of oligodendroglial tumors. In a comparison with 232 healthy controls, we retrospectively analyzed blood samples of 293 oligodendroglial tumor patients for MDM2 SNP309. In addition, the TP53 R72P polymorphism and chromosome 1p/19q status, a major biomarker in oligodendroglial tumors, were investigated. The frequencies of T/T, T/G, and G/G genotypes in patients and controls did not suggest an increased risk of oligodendroglial tumor formation correlating with MDM2 SNP309. A borderline association was found between MDM2 SNP309 and overall survival (p=0.05), but in multivariate analysis, MDM2 SNP309 did not provide prognostic information complementary to age, tumor phenotype, grade, and 1p/19q status in oligodendroglial tumors. Finally, MDM2 SNP309, alone or in combination with TP53 R72P, was not associated with oligodendroglial tumors.