TERT Promoter Status Research Articles

BIOM-24. GLIOBLASTOMA DNA ALTERATIONS AND RAPID EARLY PROGRESSION AFTER SURGERY

Abstract Glioblastoma is the most common primary brain cancer with overall poor prognosis. In the weeks following initial resection, approximately 50% of glioblastoma patients will demonstrate rapid early progression (REP) on MRI prior to the start of radiation therapy (RT). REP is associated with worse overall survival (OS), however associations between REP and biomarkers in glioblastoma have yet to be evaluated. A single institution sample of 100 patients (age 61.2 years median, 57 males) with a primary diagnosis of glioblastoma were included in this study. Patients underwent gross or subtotal resection followed by RT within 60 days of their surgery. Patients who received biopsy only were excluded. For this analysis, REP was defined as increased nodular enhancement at the border of the resection cavity between the post-operative MRI and RT planning MRI. DNA mutations were collected from commercial next generation sequencing (NGS) results. Biomarkers with a mutational incidence of >10% were used in the analysis, which included TERT promoter (N=80), EGFR (N=38), PTEN (N=40), TP53 (N=36), CDKN2A/2B (N=41), NF1 (N=16), MTAP (N=24), PIK3CA (N=14), and MGMT methylation status (N=32). Statistical analysis was performed using SPSS Statistics 28.0. Of the patients sampled, 45 met the classification of REP. The presence of EGFR alterations (p=0.001) and MGMT methylation (p=0.016) strongly correlated with REP. After multivariate linear regression, only EGFR alterations significantly correlated with REP (p=0.006). There was no significant correlation between REP or overall survival and mutations in TERT promoter, PTEN, TP53, CDKN2A/2B, NF1, MTAP, and PIK3CA. This is the first study to analyze molecular contributors to REP. We identified that EGFR alterations are most strongly correlated with REP. This suggests that patients with EGFR alterations identified on pathology should move rapidly to adjuvant therapies given their propensity to quickly re-grow after resection.

BIOM-49. FGFR ALTERATIONS IN GLIOMAS; CLINICAL, RADIOGRAPHIC AND MOLECULAR CHARACTERIZATION

Abstract BACKGROUND FGFR-TACC is the most prevalent type of gene fusion in adult gliomas. It is present in 3-6% of IDH WT (wild-type) gliomas. Due to their histopathological and molecular features, it has been suggested that FGFR3-TACC3 fusions (F3T3) gliomas represent a unique entity among IDH WT gliomas. F3T3 are potent oncogenes that confer sensitivity to FGFR inhibitors. Preliminary data showed promising results of these alterations as actionable targets by FGFR inhibitors. METHODS We retrospectively analyzed molecular data on 912 glioma patients treated at our institution from 2014 to 2023. RESULTS We identified 22 gliomas (2.5%) with FGFR alterations. Median age was 60 years, 14 were female. 14 patients (64%) self-identified as Hispanic. 18 had a diagnosis of glioblastoma, 3 had other gliomas, and one had a low-grade neuroepithelial neoplasm. Ten patients had tumor location in the temporal lobe, 6 frontal, 5 parietal, 3 occipital, 1 multifocal, and 1 basal ganglia. 19 patients had enhancing tumors, while three were non-enhancing. The most common FGFR alteration was FGFR3-TACC3 fusion in 14/22 patients, 6 had FGFR mutations (either single base or amino acid substitutions), one had FGFR-LMNB2 fusion, and one had FGFR3 amplification. 86.4% of our patient cohort (19/22) had a confirmed TERT promoter mutation, while 100% of GBM patients with known TERT promoter status had an associated TERT promoter mutation. 10/22 had CDKN2A/B alterations. One patient had pathology-proven systemic metastases. CONCLUSIONS FGFR3-TACC3 fusions (F3T3) gliomas represent a unique entity among IDH WT gliomas. In our cohort, 100% of the patients with F3T3-positive glioblastomas also had an associated TERT promoter mutation. To our knowledge, this is one of the larger cohorts showing the association between FGFR3 and TERT promoter alterations in glioblastomas. RESULTS will be validated through the upcoming clinical trial ETCTN 10559, including tumor evolution and mechanisms of resistance.

EPCO-15. DETECTING HISTOLOGIC & CLINICAL GLIOBLASTOMA PATTERNS OF PROGNOSTIC RELEVANCE

Abstract BACKGROUND Glioblastoma is the most common adult primary brain tumor. Limited improvement in patient prospects over the last 20 years reflects our limited disease understanding. Robust prognostic patient stratification from whole slide images (WSI) & clinical data using interpretable computational methods could improve disease understanding and patient management. MATERIAL AND METHODS The TCGA-GBM and TCGA-LGG data collections were reclassified according to the 2021 WHO classification criteria, identifying 188 glioblastoma (IDH-wt, Gr.4) cases and stratifying them to short- (< 9 months) and long-survivors ( > 13 months). H&E-stained WSI were comprehensively curated to remove artifactual content. An interpretability mechanism based on weakly-supervised attention-based multiple-instance-learning was employed. The prognostic relevance of associated clinical data was also evaluated both independently and integratively, using XGBoost and ‘SHapely Additive exPlanations’. Late fusion amalgamates the advantage of WSI patterns with clinical features by averaging the output probabilities of two distinct models at the decision level. Quantitative performance evaluation was based on a 10-fold monte carlo cross-validation, with training (80%), validation (10%), and test (10%) sets. RESULTS Our imaging, clinical, and integrative multi-modal models revealed AUCTest of 0.68/0.72/0.75 respectively. The imaging analysis revealed correctly predicted long-survivors associated with histologically malignant areas, including necrosis, hypercellularity, atypia, infiltration, and proliferation. Correctly classified short survivors highlighted influence by aggressive infiltrative features, including leptomeningeal involvement. The clinical analysis revealed age, mutation count, and TERT promoter status as the top three features contributing to stratification, in the XGBoost model. CONCLUSION Our findings support data-driven histology & data interpretation of algorithmic decisions contribute to further understanding of glioblastoma by identifying morphology patterns & clinical patterns of prognostic relevance. Integration of multiple modalities can be a powerful approach for improving the performance of AI models.

ATRX Loss in the Development and Prognosis of Conjunctival Melanoma.

Metastatic disease is linked to TERT promoter mutations in conjunctival melanomas (CM). Both TERT promoter and ATRX mutations are associated with faulty telomere maintenance. This study aimed to determine the prognostic value of ATRX loss in conjunctival melanocytic lesions. Eighty-six conjunctival melanocytic lesions from the Rotterdam Ocular Melanoma Study group were collected. ATRX status and TERT promoter status were determined using immunohistochemical staining and molecular diagnostics, respectively. None of the nevi (n = 16) and primary acquired melanosis (PAM) without atypia (n = 6) showed ATRX loss. ATRX loss was found in 2/5 PAM with atypia without CM and in 8/59 CM. No cases with a TERT promoter mutation (n = 26) showed ATRX loss. Eight/eleven metastatic CM harbored a TERT promoter mutation, two other metastatic CM showed ATRX loss and one metastatic case showed no TERT promoter/ATRX alterations. In conclusion ATRX loss and TERT promoter mutations are only found in (pre)malignant conjunctival melanocytic lesions, with most metastatic cases harboring one of these alterations, suggesting that both alterations are associated with adverse behavior. Similar to TERT promoter mutations, ATRX loss may be used as a diagnostic tool in determining whether a conjunctival melanocytic lesion is prone to having an adverse course.

Approach to risk stratification for papillary thyroid carcinoma based on molecular profiling: institutional analysis

Currently, treatment recommendations for papillary thyroid carcinoma are not based on the genetic background causing tumourigenesis. The aim of the present study was to correlate the mutational profile of papillary thyroid carcinoma with clinical parameters of tumour aggressiveness, to establish recommendations for risk-stratified surgical treatment. Papillary thyroid carcinoma tumour tissue of patients undergoing thyroid surgery at the University Medical Centre Mainz underwent analysis of BRAF, TERT promoter and RAS mutational status as well as potential RET and NTRK rearrangements. Mutation status was correlated with clinical course of disease. One hundred and seventy-one patients operated for papillary thyroid carcinoma were included. The median age was 48 years (range 8-85) and 69 per cent (118/171) of patients were females. One hundred and nine papillary thyroid carcinomas were BRAF-V600E mutant, 16 TERT promotor mutant and 12 RAS mutant; 12 papillary thyroid carcinomas harboured RET rearrangements and two papillary thyroid carcinomas showed NTRK rearrangements. TERT promoter mutant papillary thyroid carcinomas had a higher risk of distant metastasis (OR 51.3, 7.0 to 1048.2, P < 0.001) and radioiodine-refractory disease (OR 37.8, 9.9 to 169.5, P < 0.001). Concomitant BRAF and TERT promoter mutations increased the risk of radioiodine-refractory disease in papillary thyroid carcinoma (OR 21.7, 5.6 to 88.9, P < 0.001). RET rearrangements were associated with a higher count of tumour-affected lymph nodes (OR 7950.9, 233.7 to 270495.7, P < 0.001) but did not influence distant metastasis or radioiodine-refractory disease. Papillary thyroid carcinoma with concomitant BRAF-V600E and TERT promoter mutations demonstrated an aggressive course of disease, suggesting the need for a more extensive surgical strategy. RET rearrangement-positive papillary thyroid carcinoma did not affect the clinical outcome, potentially obviating the need for prophylactic lymphadenectomy.

Pathological features and clinicopathological significance of TERT promoter mutation in breast fibroepithelial tumors without definite diagnosis

Objective: To investigate the pathological features and the clinicopathological significance of TERT detection in those tumors that were difficult to diagnosis. Methods: A total of 93 cases of fibroepithelial tumors without definite diagnosis were collected from the Affiliated Hospital of Qigndao University between 2013 and 2021. The clinical details such as patients' age and tumor size were collected. All slides were re-reviewed and the pathologic parameters, including stromal cellularity, stromal cell atypia, stromal cell mitoses, and stromal overgrowth were re-interpreted. Sanger sequencing was used to detect TERT promoter status, and immunohistochemistry was performed to detect TERT protein expression. The relationship between TERT promoter mutation as well as protein expression levels and the clinicopathological parameters were also analyzed. Results: The patients' ages ranged from 30 to 71 years (mean of 46 years); the tumor size ranged from 1.2 to 8.0 cm (mean 3.8 cm). These tumors showed the following morphologic features: leafy structures in the background of fibroadenoma, or moderately to severely abundant stromal cells. The interpretations of tumor border status were ambiguous in some cases. The incidence of TERT promoter mutation was high in patients of age≥50 years, tumor size≥4 cm, and stromal overgrowth at ×4 or ×10 objective, and these clinicopathologic features were in favor of diagnosis of phyllodes tumors. TERT protein expression levels was not associated with the above clinicopathologic parameters and its promoter mutation status. Conclusions: The diagnostic difficulty for the breast fibroepithelial tumors is due to the difficulty in recognition of the leafy structures or in those cases with abundant stromal cells. A comprehensive evaluation combined with morphologic characteristics and molecular parameters such as TERT promoter may be helpful for the correct diagnosis and better evaluating recurrence risk.

TERT Promoter Mutations Are Enriched in Oral Cavity Cancers and Associated With Locoregional Recurrence.

We retrospectively identified patients who were diagnosed with HNSCC between July 1, 2004, and October 12, 2017, at Memorial Sloan Kettering Cancer Center and whose tumors underwent next-generation sequencing using the MSK-IMPACT panel. Patients with HPV-positive oropharyngeal squamous cell carcinoma (SCC) were excluded. Cumulative incidence of LRF, patterns of failure, and overall survival were measured. We identified 117 patients with SCC of the oral cavity (OSCC), larynx, hypopharynx, or HPV-negative oropharynx whose tumors underwent next-generation sequencing. Sequencing was performed on 95 tumors that were obtained after recurrence and 22 that were obtained before recurrence. TERT promoter mutations were enriched in OSCC compared with laryngopharyngeal cancers (81.1% v 7.0%; P < .001), which was the largest genetic difference between these anatomic disease subsites. TERT promoter mutations were associated with LRF in OSCCs (Gray's test, P < .001) and in the overall cohort (Gray's test, P < .001). On multivariate analysis, TERT promoter mutations were associated with an increased risk for LRF (subdistribution hazard ratio, 2.82; 95% CI, 1.47 to 5.42; P = .0019), independent of oral cavity primary site and TP53 mutation status. TERT promoter status is associated with the cumulative incidence of LRF and patterns of failure. TERT promoter mutations may define a subset of OSCCs with unique pathogenesis that is associated with an increased risk of LRF. Validation in prospective cohorts is warranted.

Clinical Significance of Telomerase Reverse-Transcriptase Promoter Mutations in Hepatocellular Carcinoma.

Simple SummaryActivating mutations in the promoter region of TERT (TERTp) gene are frequently observed in low- and high-grade dysplastic nodules and defined as early events in hepatocellular carcinoma development. This study shows that the nucleotide change G>A at position −124 in the TERTp region is very common in hepatocellular carcinoma. The concordance rate between droplet digital PCR (ddPCR) (63.6%) and Sanger sequencing (52.1%) detection methods is good (83.5%). HCC patients carrying the TERTp mutation had lower levels of the tumour biomarker Ca19-9 but showed reduced survival. The presence of TERTp mutations may represent a prognostic signature in liver cancer.Telomerase reactivation during hepatocarcinogenesis is recurrently caused by two point mutations occurring most frequently at the nucleotide −124 (95%) and occasionally at the nucleotide −146 (<5%) upstream of the TERT translational start site in hepatocellular carcinoma (HCC). In this study, we designed a droplet digital PCR (ddPCR) assay to detect TERT promoter (TERTp) nucleotide change G>A at position −124 and to quantify the mutant allele frequency (MAF) in 121 primary liver cancers, including 114 HCC along with 23 autologous cirrhotic tissues, five cholangiocarcinoma (CC), and two hepato-cholangiocarcinoma (HCC-CC). All cases were evaluated for tumour markers such as α-fetoprotein (AFP), carbohydrate antigen 19-9 (CA19-9), and carcinoembryonic antigen (CEA). We compared the sensitivity of ddPCR and Sanger sequencing and investigated the prognostic relevance of TERTp mutations. The TERTp G>A transition was identified in 63.6% and 52.1% of HCC samples by ddPCR and Sanger sequencing, respectively. One out of 23 (4.3%) peri-tumour tissues tested positive only by ddPCR. One out of five CC (20%) and none of the HCC-CC were found concordantly mutated by the two methods. The TERTp MAF ranged from 2% to 66%, and the large majority (85.5%) of mutated samples showed a value above 20%. A statistically significant correlation was found between TERTp mutation and tumour size (p = 0.048), while an inverse correlation was observed with CA19-9 levels (p = 0.0105). Moreover, HCC patients with TERTp −124A had reduced survival. In conclusion, the single nucleotide variation G>A at position −124 in TERTp, detected either by ddPCR or by Sanger sequencing, showed a remarkable high frequency in HCC. Such mutation is associated with lower levels of CA19-9 and reduced survival in HCC patients suggesting that the TERTp status may represent a distinct signature of liver cancer subgroups.

The clinical significance of telomerase reverse transcriptase (TERT) promoter mutations, telomere length and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status in newly diagnosed and recurrent IDH-wildtype glioblastoma (GBM) patients (PTS): A large mono-institutional study.

2053 Background: the clinical significance of TERT promoter mutations, telomere length and their interactions with MGMT promoter methylation status in patients with IDH-wildtype GBM patients remain unclear. We performed a large mono-institutional study to better investigate their impact and their interaction on clinical outcomes Methods: TERT promoter mutations (C228T and C250T), relative telomere length (RTL) and MGMT methylation status were assessed in 278 newly diagnosed and in 65 recurrent IDH-wildtype GBM PTS which were treated at Veneto Institute of Oncology (Padua, Italy) from Dec 2016 to Jan 2020. We have retrospectively explored association between gene characteristics and neuroradiological response (RANO criteria), progression-free survival (PFS), overall survival (OS). Telomere length was measured by monochrome multiplex PCR and RTL values were calculated as a telomere/single-copy gene ratio Results: characteristics of newly diagnosed GBM PTS were: median age 63 ys, ECOG PS 0-1 in 71% of PTS, radical surgery in 38%, 78% received radiation therapy plus TMZ, MGMT was methylated in 53%, TERT promoter was mutated in 80% (75% C228T, 25% C250T), median RTL was 1.57 (range 0.4-11.37). Objective response rate was reported in 15% of PTS, median OS was 15ms (95% CI 13-18ms), median PFS was 8ms (95% CI 7-9ms). At multivariable analysis, TERT promoter mutations and RTL were not associated with clinical outcomes; about OS, TERT promoter mutations and RTL reported a HR of 1.05 (95% CI 0.64-1.64) and 0.99 (95% CI 0.89-1.10), respectively; MGMT methylated tumors showed significant improved PFS and OS with a HR of 0.54 (95% CI 0.40-0.71) and 0.47 (95% CI 0.34-0.64), respectively. All interactions among MGMT status, TERT mutation status and RTL were not statistically significant. Characteristics of recurrent GBM PTS were: median age 55 ys, ECOG PS 0-1 in 60% of PTS, MGMTmet in 37%, TERT promoter mutations in 75% (75% C228T, 25% C250T), RTL was 1.67 (range 0.68-8.87). At multivariable analysis, only MGMT methylated tumors resulted significantly associated to prolonged OS (HR 0.16; 95% CI 0.07-0.40). No gene interaction was significant. Conclusions: for the first time worldwide, we analyzed the impact of TERT promoter mutations, RTL and MGMT methylation status in both newly diagnosed and recurrent IDH-wildtype GBM PTS. TERT promoter status and RTL were not associated with clinical outcomes at both diagnosis and relapse. MGMT promoter methylation status was the only prognostic factor in both cases. No significant interaction was demonstrated between TERT promoter mutations, RTL and MGMT methylation status.

Prediction of Lower Grade Insular Glioma Molecular Pathology Using Diffusion Tensor Imaging Metric-Based Histogram Parameters.

ObjectivesTo explore whether a simplified lesion delineation method and a set of diffusion tensor imaging (DTI) metric-based histogram parameters (mean, 25th percentile, 75th percentile, skewness, and kurtosis) are efficient at predicting the molecular pathology status (MGMT methylation, IDH mutation, TERT promoter mutation, and 1p19q codeletion) of lower grade insular gliomas (grades II and III).Methods40 lower grade insular glioma patients in two medical centers underwent preoperative DTI scanning. For each patient, the entire abnormal area in their b-non (b0) image was defined as region of interest (ROI), and a set of histogram parameters were calculated for two DTI metrics, fractional anisotropy (FA) and mean diffusivity (MD). Then, we compared how these DTI metrics varied according to molecular pathology and glioma grade, with their predictive performance individually and jointly assessed using receiver operating characteristic curves. The reliability of the combined prediction was evaluated by the calibration curve and Hosmer and Lemeshow test.ResultsThe mean, 25th percentile, and 75th percentile of FA were associated with glioma grade, while the mean, 25th percentile, 75th percentile, and skewness of both FA and MD predicted IDH mutation. The mean, 25th percentile, and 75th percentile of FA, and all MD histogram parameters significantly distinguished TERT promoter status. Similarly, all MD histogram parameters were associated with 1p19q status. However, none of the parameters analyzed for either metric successfully predicted MGMT methylation. The 25th percentile of FA yielded the highest prediction efficiency for glioma grade, IDH mutation, and TERT promoter mutation, while the 75th percentile of MD gave the best prediction of 1p19q codeletion. The combined prediction could enhance the discrimination of grading, IDH and TERT mutation, and also with a good fitness.ConclusionsOverall, more invasive gliomas showed higher FA and lower MD values. The simplified ROI delineation method presented here based on the combination of appropriate histogram parameters yielded a more practical and efficient approach to predicting molecular pathology in lower grade insular gliomas. This approach could help clinicians to determine the extent of tumor resection required and reduce complications, enabling more precise treatment of insular gliomas in combination with radiotherapy and chemotherapy.

MicroRNAs expression associated with aggressive clinicopathological features and poor prognosis in primary cutaneous melanomas.

Several studies have focused on identifying microRNAs involved in the pathogenesis of melanoma. However, its association with clinicopathological features has been scarcely addressed. The aim of this study is to identify microRNAs expression profiles related to aggressive clinicopathological and molecular features, and to analyze the association with melanoma survival. A retrospective and observational study was performed in a series of 179 formalin-fixed paraffin embedded primary cutaneous melanomas. First, a screening analysis on a discovery set (n = 22) using miRNA gene chip array (Affymetrix, Santa Clara, California, USA) was performed. Differentially expressed microRNAs were detected employing the software Partek Genomic Suite. Validation of four microRNAs was subsequently performed in the entire series (n = 179) by quantitative real time PCR (qRT-PCR). MicroRNAs expression screening analysis identified 101 microRNAs differentially expressed according to Breslow thickness (≤1 mm vs. >1 mm), 79 according to the presence or absence of ulceration, 78 according to mitosis/mm2 (<1 mitosis vs. ≥1 mitosis) and 97 according to the TERT promoter status (wt vs. mutated). Six microRNAs (miR-138-5p, miR-130b-3p, miR-30b-5p, miR-34a-5p, miR-500a-5p, miR-339-5p) were selected for being validated by qRT-PCR in the discovery set (n = 22). Of those, miR-138-5p, miR-130b-3p, miR-30b-5p, miR-34a-5p were selected for further analysis in the entire series (n = 179). Overexpression of miR-138-5p and miR-130b-3p was significantly associated with greater Breslow thickness, ulceration, and mitosis. TERT mutated melanomas overexpressed miR-138-5p. Kaplan-Meier survival analysis showed poorer survival in melanomas with miR-130b-3p overexpression. Our findings provide support for the existence of a microRNA expression profile in melanomas with aggressive clinicopathological features and poor prognosis.

CTNI-22. RETROSPECTIVE ANALYSIS OF THE COMBINED TREATMENT OF VINCRISTINE, ACNU, CARBOPLATIN AND INTERFERON-β PLUS RADIOTHERAPY (VAC-FERON-R)IN PATIENTS WITH DIFFUSE ASTROCYTOMA

Abstract OBJECTIVE Diffuse astrocytomas are classified as WHO grade II and its median overall survival (mOS) is 10 to 11 years. The efficacy of chemoradiation in the high-risk feature has been reported. The prognosis is associated with IDH and TERT promoter (TERTp) mutations. Here, we retrospectively analyzed the patients with diffuse astrocytoma treated with vincristine, ACNU, carboplatin and interferon-β plus radiotherapy (VAC-feron-R)in our institute. PATIENTS AND METHODS Between December 2003 to January 2016, 44 patients were diagnosed as diffuse astrocytoma with integrated diagnosis of histological and molecular analysis. The average age was 43.1 years (22–71 years). They received VAC-feron-R as initial treatment in our institute. We analyzed the IDH1/2 and the TERTp mutation using Sangar sequencing and determined the 1p/19q codeletion by the fluorescence in situ hybridization or the multiplex ligation-dependent probe amplification. RESULTS Median follow-up period was 76.5 months, mPFS was 126 months, mOS did not reach, and 10-year survival rate was 60%.IDH status was determined in 29 patients, 9 mutant and 20 wild types. There was no significant difference in PFS and OS between the two groups. TERTp status was determined in 18 patients with IDH wild type, 6 mutant and 12 wild types. mPFS of patients with TERTp wild type did not reach, but that with TERTp mutant type was 34.5 months (p = 0.0356). CONCLUSION Compared with previous clinical studies, VAC-feron-R showed a favorable clinical outcome in diffuse astrocytoma. The impact of TERTp status on prognosis was identified but not IDH status in this cohort.

RNA expression profiling reveals PRAME, a potential immunotherapy target, is frequently expressed in solitary fibrous tumors.

Solitary fibrous tumors are a type of translocation-associated sarcoma with up to 30% rates of metastasis and poor response to conventional chemotherapy. Other translocation-associated sarcomas have been shown to display elevated expression of various cancer-testis antigens which may render them susceptible to immunotherapy strategies such as cancer vaccines and adoptive T-cell therapy. After an RNA sequencing assay brought the cancer-testis antigen Preferentially Expressed Antigen In Melanoma (PRAME) to our attention as possibly being upregulated in aggressive TERT promoter-mutated solitary fibrous tumors, we used tissue microarrays to asses PRAME expression in a large series of previously characterized solitary fibrous tumors, with correlation to various clinicopathologic features, as well as with tumor-infiltrating macrophages and the associated signal regulatory protein α (SIRPα)-CD47 regulatory checkpoint. We found that PRAME was expressed in 165/180 solitary fibrous tumors, with high expression seen in 58%, irrespective of TERT promoter status. Elevated PRAME expression was more frequent in primary intrathoracic solitary fibrous tumors and correlated with older age at primary diagnosis. Elevated PRAME was also associated with features suggestive of immune evasion, including lower numbers of antigen-presenting CD163+ and CD68+ macrophages, and expression of the "don't eat me" receptor CD47 on tumor cells. Taken together, these features suggest that strategies targeting PRAME with or without concomitant SIRPα-CD47 axis inhibition may represent a potential future therapeutic option in aggressive solitary fibrous tumor.

TERT promoter mutation analysis as a surrogate to morphology and immunohistochemistry in problematic spindle cell lesions of the urinary bladder.

Pseudosarcomatous myofibroblastic proliferations (PSMPs) of the urinary bladder are diagnostically challenging. Diagnostic difficulties are mainly due to frequent cytokeratin expression, variable ALK expression and worrisome morphological features suggestive of malignancy. Conversely, sarcomatoid urothelial carcinoma (UC) may show bland inflammatory myofibroblastic tumour (IMT)-like morphology. TERT promoter mutations are characteristic events in urothelial cancers, but have not been studied in PSMPs. We compared histomorphological and immunohistochemical features and TERT promoter status in 16 PSMPs and 18 sarcomatoid UC. In a subset of PSMPs, RNA sequencing was performed. At least focal IMT-like morphology was seen in nine of 17 sarcomatoid UC. Atypical mitoses, differentiated urothelial component and heterologous elements were the most reliable distinguishing histomorphological features of sarcomatoid UC, if present. A panel of immunohistochemistry (IHC) including ALK (clone D5F3), p53 pattern, p63 and GATA3 reliably distinguished PSMP from sarcomatoid UC. GATA3 (P=0.001) and p53 patterns (mutant versus wild-type; P<0.001) were differentially expressed between PSMPs and sarcomatoid UC. Diffuse pancytokeratin staining was significantly associated with PSMPs (10 of 13) compared to four of 14 sarcomatoid UCs (P=0.012). TERT promoter mutations were found in 17 of 18 sarcomatoid UC versus none of 16 PSMPs (P<0.001). RNA sequencing revealed ALK genetic rearrangements in one of two ALK-positive and one of 10 ALK-negative PSMPs, which revealed a novel FN1/RET gene fusion. Careful histomorphological analysis and differential IHC reliably distinguish the majority of PSMPs and sarcomatoid UC. In equivocal cases, TERT promoter mutation analysis and/or detection of ALK expression/rearrangements are valuable additional diagnostic adjuncts, strongly supporting sarcomatoid UC and PSMP, respectively.

LGALS3 Is a Poor Prognostic Factor in Diffusely Infiltrating Gliomas and Is Closely Correlated With CD163+ Tumor-Associated Macrophages.

Background: Glioma, the most common brain tumor, is a heterogeneous group of glia-derived tumors, the majority of which have characteristics of diffuse infiltration and immunosuppression. The LGALS protein family is a large class of sugar-binding proteins. Among them, LGALS3 has been reported to promote tumor development and progression in some cancers. However, the clinical significance and biological functions of LGALS3 in glioma remain virtually unknown. The purpose of our research is to detect LGALS3 expression and its prognostic value in glioma and reveal the relationship between its expression and the clinico/molecular-pathological features of patients and immune cell infiltration.Methods: LGALS3 protein expression was examined by immunohistochemistry. The mRNA expression data of LGALS3 was downloaded and analyzed from TCGA and Rembrandt datasets. The association between LGALS3 and glioma clinically relevant diagnostic/molecular markers (IDH, 1p19q, ATRX, MGMT, and TERT) was examined using the Chi-Squared (χ2) test. The correlation between LGALS3 expression and the infiltration of multiple intra-tumoral immune cell types, including B cells (CD20), T cells (CD4 and CD8), macrophages (CD68), and M2 tumor-associated macrophages (CD163), was evaluated by Spearman correlation analysis. Kaplan-Meier analysis and the Cox regression analysis were applied to evaluate the prognostic value of LGALS3 in glioma. The log-rank test was used to evaluate Kaplan-Meier results for significance.Results: Out of all 304 glioma cases, LGALS3 protein was expressed in 125 glioma cases (41.1%, 125/304), with 69.2% (9/13) in WHO I, 9.8% (8/82) in WHO II, 34.2% (26/76) in WHO III, and 61.7% (82/133) in WHO IV. The expression of LGALS3 was correlated with patient age, WHO grade, PHH3 (mitosis), Ki67 index, IDH, 1p/19q codeletion, and TERT promoter status. LGALS3 was an independent poor prognostic marker in diffusely infiltrating gliomas and was positively correlated with immune cell infiltration, particularly CD163+ tumor-associated macrophages in the TCGA dataset, Rembrandt dataset, and our SYSUCC cohort (R = 0.419, 0.627, and 0.724).Conclusion: LGALS3 was highly expressed in pilocytic astrocytoma, GBM, and IDH wild-type LGG. It served as a poor prognostic marker in diffusely infiltrating gliomas. Based on its prognostic significance and strong correlation with CD163+ TAMs, it may act as an important therapeutic target for human glioma.

MPC-01 PROGNOSTIC ROLE OF TERT PROMOTER IMPROVES THE STRATIFICATION OF IDH-MUTATED LOWER GRADE GLIOMA

TERT promoter mutation is associated with favorable prognosis and 1p/19q codeletion in IDH-mutated gliomas. The current diagnostic system, however, did not incorporate this change as a diagnostic marker in this entity. We investigated the value of prognostication incorporating TERT using the Japanese original cohort of 560 IDH-mutated adult gliomas. We collected the information of molecular status of IDH, TERT and 1p/19q and patient clinical data including Karnofsky performance status (KPS). TERT mutation and 1p/19q codeletion were found in 303 and 285 cases, respectively. For the purpose of this study, the patient cohort was divided into four groups by a combination of 1p/19q and TERT status, and the characteristics of 1p/19q intact-TERT mutated group (Astro-TERT group) (n=24) were dissected in light of the differences comparing with 1p/19q intact-TERT wild (Astro-group, n=251) or 1p/19q codeleted-TERT mutated (Oligo-group, n=279) cases. Astro-TERT group with any grade showed intermediate overall survival between the Oligo-group and Astro-group although the survival differences were not statistically significant (median OS: not reached (NR) versus NR, and 106 months, respectively. p>0.05). In grade II-III gliomas, the survival curve of the Astro-TERT group overlapped with that of the Oligo-group while the Astro-TERT group showed short survival as well as the Astro-group. We further conducted subgroup analysis by adjusting KPS in grade II-III tumors. In the subgroup with favorable KPS (90–100) and gradeII-III (n=438), The OS of Astro-TERT group (median NR) was significantly longer survival than that of Astro-group (median NR p=0.032), and was comparable with that of the Oligo-group (median NR, p>0.05). Thus, TERT promoter status provides the additional information for prognostication at least in grade II-III gliomas in the current diagnostic system.

PATH-37. PROGNOSTIC ROLE OF TERT PROMOTER MUTATIONS IMPROVES THE STRATIFICATION OF IDH-MUTATED LOWER GRADE GLIOMA

Abstract TERT promoter mutation is associated with 1p/19q codeletion and favorable prognosis in IDH-mutated gliomas. Prognostic and diagnostic significance of TERT promoter mutation is well-recognized in IDH-wildtype glioblastomas, but not in IDH-mutated gliomas. We investigated prognostic efficacy of TERT mutation in a cohort of 560 Japanese IDH-mutated adult gliomas. The molecular status of IDH, TERT and 1p/19q and patient clinical data including Karnofsky performance status (KPS) were collected in all cases. TERT mutations and 1p/19q codeletions were found in 303 and 285 cases, respectively. The patient cohort was divided into four groups by a combination of the 1p/19q and TERT status. The characteristics of 1p/19q intact-TERT mutated group (Astro-TERT group, n=24) were compared with those of 1p/19q intact-TERT wild (Astro-group, n=251) or 1p/19q codeleted-TERT mutated (Oligo-group, n=279) cases. Astro-TERT group with any grade showed intermediate overall survival between the Oligo-group and Astro-group although the survival differences were not statistically significant (median overall survival (OS) not reached (NR) versus NR, and 106 months, respectively. p &gt;0.05). We further conducted subgroup analysis by adjusting KPS and WHO grade as Cox regression analysis for survival indicated the unfavorable survival impact of KPS &lt; 90 and WHO grade IV. In the subgroup with favorable KPS (90–100) and grade II-III (n=438), The OS of Astro-TERT group (median NR) was significantly longer survival than that of Astro-group (median 120.2 months, p=0.032), and was comparable with that of the Oligo-group (median NR, p &gt;0.05). On the other hand, OS of none of the molecular groups significantly differ in poorer KPS subgroups (p &gt;0.05). In grade IV tumors, the OS of the Astro-TERT group (NR) was comparable with that of Astro-group (29 months, p=0.19) rather than Oligo-group (NR, p=0.051). Thus, TERT promoter status provides a valuable prognostic information for IDH-mutated grade II-III gliomas in the current molecular diagnostic system.

Solitary fibrous tumor: a case series identifying pathological adverse factors-implications for risk stratification and classification.

Solitary fibrous tumors (SFTs) are a rare type of mesenchymal lesion in which specific clinicopathologic factors have been related to patient outcome. We collected clinical, pathological, and molecular data of 28 patients with histologically confirmed SFT having at least one pathological factor associated with aggressive behavior. Molecular analysis to detect NAB2/STAT6 gene fusion, TP53, and/or TERT promoter mutation was performed. We analyzed the pathological factors predictive of recurrence/metastasis and compared with clinical outcome. The risk of metastasis was calculated using four previously described scoring systems. Histopathologically, all tumors revealed hypercellularity, 11 had ≥ 4 mitoses/10 HPF, and 12 showed necrosis. Dedifferentiation was observed in three tumors. STAT6 was positive in all cases. Desmin, p16, INSM1, and HTER immunoexpressions were detected in 14, 18, 21, and 46% of the SFT, respectively. The NAB2/STAT6 gene fusion was detected in 16 tumors. After a median follow-up of 34months, 32.0% recurred, 32.1% metastasized, and 35.7% died of disease. TERT mutations were detected in almost half the tumors. Tumors with TP53 mutations or with TP53 and TERT promoter mutations were almost always classified as high risk, and the patients developed metastases and/or died of disease. Tumors with intermediate-risk and TERT mutation had a worse evolution. SFTs with adverse pathological parameters were not always related with a poor outcome, thus confirming the unpredictable clinical behavior of SFT. The inclusion of molecular factors (TP53 and TERT promoter status) may provide new prognostic indicators for future risk stratification systems, especially in the intermediate-risk group.

Pathological prognostic markers in central nervous system solitary fibrous tumour/hemangiopericytoma: Evidence from a small series.

BackgroundPrimary central nervous system (CNS) solitary fibrous tumour/hemangiopericytoma (SFT/HPC) is a rare neoplasm and its classification criteria have been redefined by the latest WHO Classification of CNS Tumours. Outcome can vary significantly among patients, thus reliable prognostic markers are warranted.MethodsPrimary CNS SFT/HPC diagnosed at the Pathology Unit of our Institution between 2006 and 2016 were retrospectively collected. Tumour grade along with immunohistochemistry for Ki67, STAT6, PHH3, CD34 and Bcl-2 were assessed. TERT promoter status was evaluated by Sanger sequencing.ResultsFifteen SFT/HPC were analysed: 9/15 (60%) female, median age at diagnosis 60 (range: 10–67). Six (40%) cases showed a SFT phenotype and mean H&E-mitotic count was 4.8/10 HPF. Tumour grade was I in 6, II in 4 and III in 5 cases. Mean PHH3-mitotic count was higher than H&E count (8.4 versus 4.8/10 HPF), but it would have determined a change in tumour grade in a sole case. Nuclear staining for STAT6 was present in 14/15 (93.3%). CD34 and Bcl-2 expression rates were lower in higher grade tumours. TERT promoter was mutated in two cases. Median follow up time was 2.4 years (6 months-7.4 years) and 5/15 (33%) patients developed local disease recurrence. Partial resection (p = 0.0185), higher WHO grade (p = 0.038), lower CD34 (p = 0.038) and Bcl-2 (p = 0.010) expressions were significantly associated with a poorer disease-free interval.ConclusionsWHO grade is the main prognostic tool in CNS SFT/HPC, but it could be integrated by other markers, like CD34 and Bcl-2, in the clinical practice. The relevance of TERT promoter mutations in this subset of CNS tumours needs further evaluation.

Abstract 3117: Eribulin is a novel TERT-targeting inhibitor that penetrates into intracerebrally grown glioblastomas and suppresses their growth in mice

Abstract [Introduction] No effective molecular targeting therapy has been clinically developed for patients with glioblastoma (GBM) despite of intense genome analysis. Approximately 60-80% of GBM harbor mutations in the promoter region of TERT that leads to its upregulation, making it the most common single genetic abnormalities in GBM. TERT, a reverse-transcriptase subunit of telomerase, has been an attractive candidate for therapy target because of their observed upregulation in a wide variety of cancers, including GBMs, a phenomenon that presumably helps maintain telomeres for their indefinite proliferation. It has been reported recently that TERT has an RNA-dependent RNA polymerase (RdRP) activity, with which TERT is involved in maintenance of stem cell phenotype and mitotic progression. We have previously identified eribulin as a specific inhibitor of RdRP activity of TERT through drug screening and shown that eribulin suppressed growth of ovarian cancers with high TERT expression. In order to investigate an efficacy of eribulin as a novel TERT-targeted therapy against GBM, we investigated the antitumor effect of eribulin in cultured cell and brain tumor model using GBM cell lines. [Methods] The TERT promoter status was examined in 20 glioma cell lines. Seven cell lines were subjected to in vitro cytotoxicity assay. U87MG was either subcutaneously or intracranially transplanted in athymic mice. Tissue or plasma concentration of eribulin was measured by LC-MS/MS. [Results] All GBM cell lines tested that harbored TERT promoter mutations including U87MG, U251MG, U118MG as well as several patient-derived glioblastoma sphere culture cells were highly sensitive to eribulin, IC50 below 1nM. Intraperitoneal administration of eribulin completely suppressed the growth of U87MG subcutaneous tumor in nude mice, and the RdRP activities in treated tumors were significantly decreased in a dose-dependent manner. In the brain tumor model, a high concentration of eribulin was detected in the brain tumor tissues as early as 15 minutes after intravenous injection of eribulin, which remained stable even 24 hours later when the plasma concentration of eribulin became undetectable. Finally, intraperitoneal administration of eribulin significantly prolonged the survival of mice with intracerebrally transplanted U87MG xenograft (p&amp;lt;0.001). [Conclusion] Our results showed that eribulin efficiently transfers into brain tumor tissues and has a strong antitumor effect against GBM cells through inhibition of RdRP activity. Eribulin thus appears to be a promising novel TERT-targeting therapeutic agent against GBM. A clinical trial is being scheduled. Citation Format: Masamichi Takahashi, Shunichiro Miki, Yuko Matsushita, Kohei Fukuoka, Yoshiko Maida, Mami Yasukawa, Mitsuhiro Hayashi, Akinobu Hamada, Akitake Mukasa, Ryo Nishikawa, Kenji Tamura, Yoshitaka Narita, Kenkichi Masutomi, Koichi Ichimura. Eribulin is a novel TERT-targeting inhibitor that penetrates into intracerebrally grown glioblastomas and suppresses their growth in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3117. doi:10.1158/1538-7445.AM2017-3117