Prognostic significance of TERT promoter mutations in adult-type diffuse gliomas

Characterization of MRI findings by pTERT mutation status and the prognostic significance in GBM patients with recurrent lesions

AIM

To investigate the MRI characteristics of recurrent glioblastoma (GBM) in relation to telomerase reverse transcriptase-promoter (pTERT) mutation status and their prognostic significance.

MATERIALS AND METHODS

A retrospective analysis was conducted on 80 patients with primary IDH wild-type GBM. MRI features, including conventional and functional imaging, were compared between pTERT mutant and wild-type groups. Cox regression and receiver operating characteristic (ROC) analyses were performed to evaluate survival outcomes and predictive models.

RESULTS

Compared to patients with wild-type pTERT (n = 24), those with mutant pTERT (n = 56) were older (p = 0.008) and had shorter overall survival (OS) (p = 0.003). They also exhibited a higher incidence of massive-like enhancement (p = 0.036) and new subependymal enhancement (p = 0.034), lower relative apparent diffusion coefficient (rADC) (p = 0.006), and higher relative cerebral blood volume (rCBV) (p = 0.048) and choline/N-acetyl aspartate ratio (p = 0.033). Multivariate analysis identified new subependymal enhancement (HR = 2.348, p = 0.018) and massive-like enhancement (HR = 2.348, p = 0.018) as independent risk factors for shorter OS. The areas under the ROC curve (AUCs) for predicting poor OS using pTERT mutation status, conventional MRI, and combination models were 0.700, 0.695, and 0.764, respectively. Among the 31 patients with available functional MRI data, the AUCs for prediction using functional MRI, conventional MRI + pTERT mutation status, and the combination model were 0.783, 0.710, and 0.888, respectively.

CONCLUSIONS

MRI features, particularly subependymal and massive-like enhancements, along with pTERT mutation status, serve as valuable prognostic markers for survival outcomes in recurrent GBM patients. The combination model incorporating MRI characteristics and genetic status enhances predictive accuracy.

TERT promoter mutations in gliomas: Molecular roles in tumorigenesis, metastasis, diagnosis, prognosis, therapeutic targeting, and drug resistance

Telomerase reverse transcriptase (TERT), a critical player in cellular immortalization, has emerged as a focal point of investigation due to its frequent promoter mutations in various human malignancies. TERT promoter mutations exhibit a significant role in tumorigenesis, fostering unbridled cellular proliferation and survival. This comprehensive review delves into the landscape of TERT promoter mutations and their profound implications in cancer, particularly within the context of gliomas. This article meticulously examines the intricate interplay between TERT promoter mutations and the metastatic cascade, shedding light on their capacity to orchestrate invasive behavior in gliomas. Moreover, this review describes the recent trends in therapeutic targeting of the TERT and dissects the evolving landscape of drug resistance associated with TERT mutations, providing insights into potential therapeutic challenges. In addition, the diagnostic and prognostic implications of TERT promoter mutations in gliomas are scrutinized, unraveling their potential as robust biomarkers. It also discusses the recent advancements in molecular diagnostics, illustrating the promise of TERT mutations as diagnostic tools and prognostic indicators. This review collectively aims to contribute to a deeper understanding of TERT promoter mutations in gliomas, offering a foundation for future research endeavors and paving the way for innovative strategies in glioma management.

Potential of sonobiopsy as a novel diagnosis tool for brain cancer

Brain tumors have a poor prognosis. Early, accurate diagnosis and treatment are crucial. Although brain surgical biopsy can provide an accurate diagnosis, it is highly invasive and risky and is not suitable for follow-up examination. Blood-based liquid biopsies have a low detection rate of tumor biomarkers and limited evaluation ability due to the existence of the blood-brain barrier (BBB). The BBB is composed of brain capillary endothelial cells through tight junctions, which prevents the release of brain tumor markers to the human peripheral circulation, making it more difficult to diagnose, predict prognosis, and evaluate therapeutic response through brain tumor markers than other tumors. Focused ultrasound (FUS)-enabled liquid biopsy (sonobiopsy) is an emerging technique using FUS to promote the release of tumor markers into the circulatory system and cerebrospinal fluid, thus facilitating tumor detection. The feasibility and safety data from both animal models and clinical trials support sonobiopsy as a great potential in the diagnosis of brain diseases.

Comparative analysis of molecular and histological glioblastomas: insights into prognostic variance

PURPOSE

Whether molecular glioblastomas (GBMs) identify with a similar dismal prognosis as a "classical" histological GBM is controversial. This study aimed to compare the clinical, molecular, imaging, surgical factors, and prognosis between molecular GBMs and histological GBMs.

METHODS

Retrospective chart and imaging review was performed in 983 IDH-wildtype GBM patients (52 molecular GBMs and 931 histological GBMs) from a single institution between 2005 and 2023. Propensity score-matched analysis was additionally performed to adjust for differences in baseline variables between molecular GBMs and histological GBMs.

RESULTS

Molecular GBM patients were substantially younger (58.1 vs. 62.4, P = 0.014) with higher rate of TERTp mutation (84.6% vs. 50.3%, P < 0.001) compared with histological GBM patients. Imaging showed higher incidence of gliomatosis cerebri pattern (32.7% vs. 9.2%, P < 0.001) in molecular GBM compared with histological GBM, which resulted in lesser extent of resection (P < 0.001) in these patients. The survival was significantly better in molecular GBM compared to histological GBM (median OS 30.2 vs. 18.4 months, P = 0.001). The superior outcome was confirmed in propensity score analyses by matching histological GBM to molecular GBM (P < 0.001).

CONCLUSION

There are distinct clinical, molecular, and imaging differences between molecular GBMs and histological GBMs. Our results suggest that molecular GBMs have a more favorable prognosis than histological GBMs.

Prognostic Impact of TERT Promoter Mutations in Adult-Type Diffuse Gliomas Based on WHO2021 Criteria

Mutation in the telomerase reverse transcriptase promoter (TERTp )is commonly observed in various malignancies, such as central nervous system (CNS) tumors, malignant melanoma, bladder cancer, and thyroid carcinoma. These mutations are recognized as significant poor prognostic factors for these tumors. In this investigation, a total of 528 cases of adult-type diffuse gliomas diagnosed at a single institution were reclassified according to the 2021 WHO classifications of CNS tumors, 5th edition (WHO2021). The study analyzed clinicopathological and genetic features, including TERTp mutations in each tumor. The impact of known prognostic factors on patient outcomes was analyzed through Kaplan-Meier survival and Cox regression analysis. TERTp mutations were predominantly identified in 94.1% of oligodendrogliomas (ODG), followed by 66.3% in glioblastoma, IDH-wildtype (GBM-IDHwt), and 9.2% of astrocytomas, IDH-mutant (A-IDHm). When considering A-IDHm and GBM as astrocytic tumors (Group 1) and ODGs (Group 2), TERTp mutations emerged as a significant adverse prognostic factor (p = 0.013) in Group 1. However, within each GBM-IDHwt and A-IDHm, the presence of TERTp mutations did not significantly impact patient prognosis (p = 0.215 and 0.268, respectively). Due to the high frequency of TERTp mutations in Group 2 (ODG) and their consistent prolonged survival, a statistical analysis to evaluate their impact on overall survival was deemed impractical. When considering MGMTp status, the combined TERTp-mutated and MGMTp-unmethylated group exhibited the worst prognosis in OS (p = 0.018) and PFS (p = 0.034) of GBM. This study confirmed that the classification of tumors according to the WHO2021 criteria effectively reflected prognosis. Both uni- and multivariate analyses in GBM, age, MGMTp methylation, and CDKN2A/B homozygous deletion were statistically significant prognostic factors while in univariate analysis in A-IDHm, grade 4, the Ki-67 index and MYCN amplifications were statistically significant prognostic factors. This study suggests that it is important to classify and manage tumors based on their genetic characteristics in adult-type diffuse gliomas.

The C250T Mutation of TERTp Might Grant a Better Prognosis to Glioblastoma by Exerting Less Biological Effect on Telomeres and Chromosomes Than the C228T Mutation

The aim of this study was to determine how TERTp mutations impact glioblastoma prognosis.

MATERIALS AND METHODS

TERTp mutations were assessed in a retrospective cohort of 258 uniformly treated glioblastoma patients. RNA-sequencing and whole exome sequencing results were available in a subset of patients.

RESULTS

Overall, there were no differences in outcomes between patients with mutated TERTp-wt or TERTp. However, we found significant differences according to the type of TERTp mutation. Progression-free survival (mPFS) was 9.1 months for those with the C250T mutation and 7 months for those with either the C228T mutation or TERTp-wt (p = 0.016). Overall survival (mOS) was 21.9 and 15 months, respectively (p = 0.026). This differential effect was more pronounced in patients with MGMTp methylation (mPFS: p = 0.008; mOS: p = 0.021). Multivariate analysis identified the C250T mutation as an independent prognostic factor for longer mOS (HR 0.69; p = 0.044). We found no differences according to TERTp mutation status in molecular alterations common in glioblastoma, nor in copy number variants in genes related to alternative lengthening of telomeres. Nevertheless, in the gene enrichment analysis adjusted for MGMTp methylation status, some Reactome gene sets were differentially enriched, suggesting that the C250T mutation may exert a lesser effect on telomeres or chromosomes.

CONCLUSIONS

In our series, patients exhibiting the C250T mutation had a more favorable prognosis compared to those with either TERPp-wt or TERTp C228T mutations. Additionally, our findings suggest a reduced involvement of the C250T mutation in the underlying biological mechanisms related to telomeres.

A Novel Type of IDH-wildtype Glioma Characterized by Gliomatosis Cerebri-like Growth Pattern, TERT Promoter Mutation, and Distinct Epigenetic Profile

Diffuse gliomas in adults encompass a heterogenous group of central nervous system neoplasms. In recent years, extensive (epi-)genomic profiling has identified several glioma subgroups characterized by distinct molecular characteristics, most importantly IDH1/2 and histone H3 mutations. A group of 16 diffuse gliomas classified as "adult-type diffuse high-grade glioma, IDH-wildtype, subtype F (HGG-F)" was identified by the DKFZ v12.5 Brain Tumor Classifier . Histopathologic characterization, exome sequencing, and review of clinical data was performed in all cases. Based on unsupervised t -distributed stochastic neighbor embedding and clustering analysis of genome-wide DNA methylation data, HGG-F shows distinct epigenetic profiles separate from established central nervous system tumors. Exome sequencing demonstrated frequent TERT promoter (12/15 cases), PIK3R1 (11/16), and TP53 mutations (5/16). Radiologic characteristics were reminiscent of gliomatosis cerebri in 9/14 cases (64%). Histopathologically, most cases were classified as diffuse gliomas (7/16, 44%) or were suspicious for the infiltration zone of a diffuse glioma (5/16, 31%). None of the cases demonstrated microvascular proliferation or necrosis. Outcome of 14 patients with follow-up data was better compared to IDH-wildtype glioblastomas with a median progression-free survival of 58 months and overall survival of 74 months (both P <0.0001). Our series represents a novel type of adult-type diffuse glioma with distinct molecular and clinical features. Importantly, we provide evidence that TERT promoter mutations in diffuse gliomas without further morphologic or molecular signs of high-grade glioma should be interpreted in the context of the clinicoradiologic presentation as well as epigenetic profile and may not be suitable as a standalone marker for glioblastoma, IDH-wildtype.

IDH wild-type lower-grade gliomas with glioblastoma molecular features: a systematic review and meta-analysis

The WHO 2021 classification defines IDH wild type (IDHw) histologically lower-grade glioma (hLGG) as molecular glioblastoma (mGBM) if TERT promoter mutation (pTERTm), EGFR amplification or chromosome seven gain and ten loss aberrations are indicated. We systematically reviewed articles of IDHw hLGGs studies (49 studies, N = 3748) and meta-analyzed mGBM prevalence and overall survival (OS) according to the PRISMA statement. mGBM rates in IDHw hLGG were significantly lower in Asian regions (43.7%, 95% confidence interval [CI: 35.8-52.0]) when compared to non-Asian regions (65.0%, [CI: 52.9-75.4]) (P = 0.005) and were significantly lower in fresh-frozen specimen when compared to formalin-fixed paraffin-embedded samples (P = 0.015). IDHw hLGGs without pTERTm rarely expressed other molecular markers in Asian studies when compared to non-Asian studies. Patients with mGBM had significantly longer OS times when compared to histological GBM (hGBM) (pooled hazard ratio (pHR) 0.824, [CI: 0.694-0.98], P = 0.03)). In patients with mGBM, histological grade was a significant prognostic factor (pHR 1.633, [CI: 1.09-2.447], P = 0.018), as was age (P = 0.001) and surgical extent (P = 0.018). Although bias risk across studies was moderate, mGBM with grade II histology showed better OS rates when compared to hGBM.

Favorable prognostic impact of phosphatase and tensin homolog alterations in wild-type isocitrate dehydrogenase and telomerase reverse transcriptase promoter glioblastoma

Background

Telomerase reverse transcriptase promoter (TERTp) mutations are a biological marker of glioblastoma; however, the prognostic significance of TERTp mutational status is controversial. We evaluated this impact by retrospectively analyzing the outcomes of patients with isocitrate dehydrogenase (IDH)- and TERTp-wild-type glioblastomas.

Methods

Using custom next-generation sequencing, we analyzed 208 glioblastoma samples harboring wild-type IDH.

Results

TERTp mutations were detected in 143 samples (68.8%). The remaining 65 (31.2%) were TERTp-wild-type. Among the TERTp-wild-type glioblastoma samples, we observed a significant difference in median progression-free survival (18.6 and 11.4 months, respectively) and overall survival (not reached and 15.7 months, respectively) in patients with and without phosphatase and tensin homolog (PTEN) loss and/or mutation. Patients with TERTp-wild-type glioblastomas with PTEN loss and/or mutation were younger and had higher Karnofsky Performance Status scores than those without PTEN loss and/or mutation. We divided the patients with TERTp-wild-type into 3 clusters using unsupervised hierarchical clustering: Good (PTEN and TP53 alterations; lack of CDKN2A/B homozygous deletion and platelet-derived growth factor receptor alpha (PDGFRA) alterations), intermediate (PTEN alterations, CDKN2A/B homozygous deletion, lack of PDGFRA, and TP53 alterations), and poor (PDGFRA and TP53 alterations, CDKN2A/B homozygous deletion, and lack of PTEN alterations) outcomes. Kaplan-Meier survival analysis indicated that these clusters significantly correlated with the overall survival of TERTp-wild-type glioblastoma patients.

Conclusions

Here, we report that PTEN loss and/or mutation is the most useful marker for predicting favorable outcomes in patients with IDH- and TERTp-wild-type glioblastomas. The combination of 4 genes, PTEN, TP53, CDKN2A/B, and PDGFRA, is important for the molecular classification and individual prognosis of patients with IDH- and TERTp-wild-type glioblastomas.

Molecular Genetic Profile of 300 Japanese Patients with Diffuse Gliomas Using a Glioma-tailored Gene Panel

Rapid technological advances in molecular biology, including next-generation sequencing, have identified key genetic alterations in central nervous system (CNS) tumors. Accordingly, the fifth edition of the World Health Organization (WHO) CNS tumor classification was published in 2021. We analyzed 303 patients with diffuse glioma using an amplicon-based glioma-tailored gene panel for detecting 1p/19q codeletion and driver gene mutations such as IDH1/2, TERTp, EGFR, and CDKN2A/B on a single platform. Within glioblastomas (GBMs), the most commonly mutated genes were TERTp, TP53, PTEN, NF1, and PDGFRA, which was the most frequently mutated tyrosine kinase receptor in GBM, followed by EGFR. The genes that most commonly showed evidence of loss were PTEN, CDKN2A/B, and RB1, whereas the genes that most commonly showed evidence of gain/amplification were EGFR, PDGFRA, and CDK4. In 22 grade III oligodendroglial tumors, 3 (14%) patients had CDKN2A/B homozygous deletion, and 4 (18%) patients had ARID1A mutation. In grade III oligodendroglial tumors, an ARID1A mutation was associated with worse progression-free survival. Reclassification based on the WHO 2021 classification resulted in 62.5% of grade II/III isocitrate dehydrogenase (IDH)-wildtype astrocytomas being classified as IDH-wildtype GBM and 37.5% as not elsewhere classified. In summary, our glioma-tailored gene panel was applicable for molecular diagnosis in the WHO 2021 classification. In addition, we successfully reclassified the 303 diffuse glioma cases based on the WHO 2021 classification and clarified the genetic profile of diffuse gliomas in the Japanese population.

Gliomas: Genetic alterations, mechanisms of metastasis, recurrence, drug resistance, and recent trends in molecular therapeutic options

Glioma is the most common intracranial tumor with poor treatment outcomes and has high morbidity and mortality. Various studies on genomic analyses of glioma found a variety of deregulated genes with somatic mutations including TERT, TP53, IDH1, ATRX, TTN, etc. The genetic alterations in the key genes have been demonstrated to play a crucial role in gliomagenesis by modulating important signaling pathways that alter the fundamental intracellular functions such as DNA damage and repair, cell proliferation, metabolism, growth, wound healing, motility, etc. The SPRK1, MMP2, MMP9, AKT, mTOR, etc., genes, and noncoding RNAs (miRNAs, lncRNAs, circRNAs, etc) were shown mostly to be implicated in the metastases of glioma. Despite advances in the current treatment strategies, a low-grade glioma is a uniformly fatal disease with overall median survival of ∼5-7 years while the patients bearing high-grade tumors display poorer median survival of ∼9-10 months mainly due to aggressive metastasis and therapeutic resistance. This review discusses the spectrum of deregulated genes, molecular and cellular mechanisms of metastasis, recurrence, and its management, the plausible causes for the development of therapy resistance, current treatment options, and the recent trends in malignant gliomas. Understanding the pathogenic mechanisms and advances in molecular genetics would aid in the novel diagnosis, prognosis, and translation of pathogenesis-based treatment opportunities which could pave the way for precision medicine in glioma.

Role of TERT mutation for treatment prognosis in patients with IDH-negative anaplastic astrocytoma

OBJECTIVE

To study the effect of TERT mutation on overall and relapse-free survival in patients with IDH-negative diffuse astrocytomas grade III (anaplastic gliomas).

MATERIAL AND METHODS

The study included 45 patients aged 45.5 years. Forty-two patients underwent resection of tumor, other 3 ones - stereotactic biopsy. TERT mutation was identified in 21 patients. External beam radiation therapy was performed in 35 patients (60 Gy), chemotherapy - in 34 patients (mainly temozolomide). Follow-up data were available in 44 patients.

RESULTS

Median of overall survival in patients with TERT mutation was 15.3 months, in patients with TERT-negative tumors - 65.1 months. Median of relapse-free survival in patients with TERT-positive anaplastic astrocytoma (AA) was 13.3 months, in patients with TERT-negative glioma - 57.7 months. These differences were not significant. Relapse-free survival was higher in patients with AA and no TERT mutation at all intervals, but especially at early stages (12 and 24 months).

CONCLUSION

Inclusion of TERT mutation in mandatory examination panel for gliomas in general and, in particular, gliomas grade II/III without IDH mutation can lead to sub-classification of these tumors in the near future. Routine analysis of TERT mutation in these patients will be valuable for correct medical consultation regarding prognosis and adequate adjuvant treatment.