Postmortem Study of Organ-Specific Toxicity in Glioblastoma Patients Treated with a Combination of Temozolomide, Irinotecan and Bevacizumab

Purpose Systemic monotherapy with temozolomide (TMZ) or bevacizumab (BEV); two-drug combinations, such as Irinotecan (IRI) and BEV, TMZ and BEV and a three-drug combination with TMZ, IRI and BEV (TIB) have been used in treating patients with progressive high-grade gliomas including glioblastoma. Most patients tolerated these regimens well with well-established sides effects of hypertension, proteinuria, and reversible clinical myelosuppression (CM). However, organ-specific toxicities have never been examined by postmortem studies. Methods Postmortem tissues (from all major organs) were prospectively collected and examined by standard institution autopsy and brain cutting procedures from 76 decedents, including gliomas (N=68, 44/M, and 24/F) and brain metastases (N=8, 5/M, and 3/F) between 2009 and 2019. Standard hematoxylin and eosin (H&E) were performed on all major organs and brain samples harvested. Electronic microscopic (EM) study was carried on selected subjects kidney samples per standard EM protocol. Results Twenty-four glioma subjects were treated with TIB [median: 5.5 (range: 1-25) cycles] at glioma recurrence. Exposure to IRI significantly increased the frequency of CM (p=0.05). No unexpected adverse events were detected clinically or permenant end-organ damage by postmortem examination among subjects who received TIB compared to subjects who received standard of care (SOC) therapies. Among glioma decedents, the most common causes of death (COD) were tumor progression (63.2%, N=43), followed by aspiration pneumonia (48.5%, N=33). No COD was attributed to acute toxicity from TIB. The study also demonstrated that postmortem kidney specimen is unsuitable for studying renal ultrastructural pathological changes due to autolysis. Conclusion IRI, but not the extended use of TMZ, significantly increased CM in recurrent glioma patients. There is no permanent organ-specific toxicity among glioma decedents who received prolonged BEV, TMZ or TIB regimen based chemotherapies except expected occasional myelosuppresson. COD are most commonly resulted from glioma tumor progression and aspiration pneumonia.

PIK3CA Mutations in Diffuse Gliomas: An Update on Molecular Stratification, Prognosis, Recurrence, and Aggressiveness

Introduction: PIK3CA is one of the most mutated oncogenes in solid tumors. In breast cancer (ER-positive, HER2-negative), these events represent a predictive biomarker of response to alpelisib. In glioblastomas (GBM), PIK3CA mutations were described as early constitutive events. Here, we investigated PIK3CA mutational profile across glioma molecular subgroups and its relevance during glioma recurrence. Furthermore, PIK3CA mutations’ effect in PI3K pathway, prognosis, and response to therapy was also explored. Material and Methods: Exons 10 and 21 of PIK3CA mutations were evaluated in 394 gliomas and 19 glioma recurrences from Instituto Português de Oncologia Lisboa Francisco Gentil (IPOLFG) and compared with The Cancer Genome Atlas (TCGA) data. TIMER2.0 and NetMHCpan4.1 were used to assess the immune-microenvironment contribution. Results: PIK3CA mutations were identified among all glioma subgroups, although with no impact on their stratification or prognosis. In both cohorts (IPOLFG and TCGA), PIK3CA mutation frequencies in IDH-mutant and IDH-wild-type GBM were similar (IPOLFG: 9% and 3%; TCGA: 8% and 2%). These mutations were not mutually exclusive with PTEN deletion and EGFR amplification. Despite their reduced frequency, we discovered PIK3CA mutations were maintained during glioma recurrence regardless of administered therapies. The immune microenvironment might not contribute to this phenotype as PIK3CA mutations did not influence immune cell infiltration. Conclusions: Despite the absence of a predominant effect in glioma stratification, PIK3CA mutations were maintained during glioma recurrence, possibly contributing to glioma cell survival, representing promising therapeutic targets in recurrent glioma. Nevertheless, understanding the potential synergistic effects between PIK3CA mutations, PTEN deletion, and EGFR amplification is pivotal to targeted therapies’ efficiency.

MEOX2 Transcription Factor Is Involved in Survival and Adhesion of Glioma Stem-like Cells

The high expression of MEOX2 transcription factor is closely associated with poor overall survival in glioma. MEOX2 has recently been described as an interesting prognostic biomarker, especially for lower grade glioma. MEOX2 has never been studied in glioma stem-like cells (GSC), responsible for glioma recurrence. The aim of our study was to investigate the role of MEOX2 in GSC. Loss of function approach using siRNA was used to assess the impact of MEOX2 on GSC viability and stemness phenotype. MEOX2 was localized in the nucleus and its expression was heterogeneous between GSCs. MEOX2 expression depends on the methylation state of its promoter and is strongly associated with IDH mutations. MEOX2 is involved in cell proliferation and viability regulation through ERK/MAPK and PI3K/AKT pathways. MEOX2 loss of function correlated with GSC differentiation and acquisition of neuronal lineage characteristics. Besides, inhibition of MEOX2 is correlated with increased expression of CDH10 and decreased pFAK. In this study, we unraveled, for the first time, MEOX2 contribution to cell viability and proliferation through AKT/ERK pathway and its potential involvement in phenotype and adhesion properties of GSC.

C.4 Epigenetic drivers of malignant transformation in diffuse gliomas

Background: Despite treatment, gliomas often exhibit disease progression, leading to recurrent glioblastoma (GBM) or malignant transformation of low-grade gliomas (LGG) associated with treatment resistance and poor prognosis. To date, the molecular factors driving glioma recurrence are poorly understood. Methods: We analyzed a cohort of 324 glioma samples from our institution including a unique cohort of 81 patients with matched primary and recurrent tumour pairs. We performed a paired, integrated multi-platform analysis consisting of DNA methylation profiling on all 324 samples, gene expression on 87 samples, and matched plasma cell-free DNA methylome analysis on 82 samples. Results: LGG that undergo malignant transformation are associated with DNA hypomethylation at recurrence, including decreased tumour purity and increased copy number variation. Integrated pathway analyses identified IL-6, associated with multiple pro-oncogenic pathways, and CCR2, associated with the recruitment of tumour-associated macrophages, as top genes involved in malignant transformation. Matched plasma methylation demonstrated a shift in the methylation signature at recurrence that can prove valuable as a non-invasive biomarker for early detection of malignant progression. Conclusions: We provide the first detailed description of the epigenetic evolution of gliomas and identify epigenetic drivers of malignant transformation including non-invasive biomarkers for early detection of malignant progression.

A Novel Nomogram for Predicting the Risk of Short-Term Recurrence After Surgery in Glioma Patients

ObjectiveThe aim of this study was to establish a nomogram model for predicting the risk of short-term recurrence in glioma patients.MethodsThe clinical data of recurrent glioma patients were summarized and analyzed in this study. Univariate and multivariate logistic regression analyses were performed to analyze the correlation between clinical data and the risk of short-term recurrence after operation. A nomogram was established based on the multivariate logistic regression model results.ResultsA total of 175 patients with recurrent glioma were enrolled, with 53 patients in the short-term recurrence (STR) group (recurrent time ≤6 months) and 122 patients in the long-term recurrence (LTR) group (recurrent time ≥36 months). Univariate analysis revealed that age at diagnosis, Karnofsky performance scores (KPSs), tumor location, glioma grade, glioma type, extent of resection (EOR), adjuvant chemotherapy (ad-CT), concurrent chemotherapy (co-CT), and isocitrate dehydrogenase (IDH) status were significantly associated with the short-term glioma recurrence. Multivariate analyses revealed that age at diagnosis, KPS, glioma grade, EOR, and IDH were independent risk factors for short-term glioma recurrence. A risk nomogram for the short-term recurrence of glioma was established, with the concordance index (C-index) of 0.971. The findings of calibration and receiver operating characteristic (ROC) curves showed that our nomogram model had good performance and discrimination to estimate short-term recurrence probability.ConclusionThis nomogram model provides reliable information about the risk of short-term glioma recurrence for oncologists and neurosurgeons. This model can predict the short-term recurrence probability and give assistance to decide the interval of follow-up or formulate individualized treatment strategies based on the predicted results. A free online prediction risk tool for this nomogram is provided: https://rj2021.shinyapps.io/Nomogram_ recurrence-risk/.

Diagnostic and Prognostic Potential of 18F-FET PET in the Differential Diagnosis of Glioma Recurrence and Treatment-Induced Changes After Chemoradiation Therapy

BackgroundMRI-based differential diagnosis of glioma recurrence (GR) and treatment-induced changes (TICs) remain elusive in up to 30% of treated glioma patients. We aimed to determine 18F-FET PET diagnostic performance in this clinical scenario, its outcome dependency on established prognostic factors, optimal 18F-FET semi-quantitative thresholds, and whether 18F-FET parameters may instantly predict progression-free survival (PFS) and overall survival (OS).MethodsWe retrospectively analyzed 45 glioma patients treated with chemoradiation therapy (32 males; mean age: 51 years, glioma grade: n=26 WHO4; n=15 WHO3; n=4 WHO2) who underwent 18F-FET PET to resolve differential diagnosis of GR and TICs raised by MRI performed in the preceding 2 weeks and depicting any of the following changes in their radiation field: volumetric increase of contrast-enhancing lesions; new contrast-enhancing lesion; significant increase in T2/FLAIR non-enhancing lesion without reducing corticosteroids. 18F-FET PET outcome relied on evaluation of maximum tumor-to-brain ratio (TBRmax), time-to-peak (TTP), and time-activity curve pattern (TAC). Metabolic tumor volume (MTV) and total tumor metabolism (TTM) were calculated for prognostic purposes. Standard of reference was repeat MRI performed 4–6 weeks after the previous MRI. Non-parametric statistics tested 18F-FET-based parameters for dependency on established prognostic markers. ROC curve analysis determined optimal cutoff values for 18F-FET semi-quantitative parameters. 18F-FET parameters and prognostic factors were evaluated for PFS and OS by Kaplan-Meier, univariate, and multivariate analyses.Results18F-FET PET sensitivity, specificity, positive predictive value, negative predictive value were 86.2, 81.3, 89.3, 76.5%, respectively; higher diagnostic accuracy was yielded in IDH-wild-type glioma patients compared to IDH-mutant glioma patients (sensitivity: 81.8 versus 88.9%; specificity: 80.8 versus 81.8%). KPS was the only prognostic factor differing according to 18F-FET PET outcome (negative versus positive). Optimal 18F-FET cutoff values for GR were TBRmax ≥ 2.1, SUVmax ≥ 3.5, and TTP ≤ 29 min. PFS differed based on 18F-FET outcome and related metrics and according to KPS; a different OS was observed according to KPS only. On multivariate analysis, 18F-FET PET outcome was the only significant PFS factor; KPS and age the only significant OS factors.Conclusion18F-FET PET demonstrated good diagnostic performance. 18F-FET PET outcome and metrics were significantly predictive only for PFS.

Dynamic 11C-Methionine PET-CT: Prognostic Factors for Disease Progression and Survival in Patients with Suspected Glioma Recurrence

Purpose: The prognostic evaluation of glioma recurrence patients is important in the therapeutic management. We investigated the prognostic value of 11C-methionine PET-CT (MET-PET) dynamic and semiquantitative parameters in patients with suspected glioma recurrence. Methods: Sixty-seven consecutive patients who underwent MET-PET for suspected glioma recurrence at MR were retrospectively included. Twenty-one patients underwent static MET-PET; 46/67 underwent dynamic MET-PET. In all patients, SUVmax, SUVmean and tumour-to-background ratio (T/B) were calculated. From dynamic acquisition, the shape and slope of time-activity curves, time-to-peak and its SUVmax (SUVmaxTTP) were extrapolated. The prognostic value of PET parameters on progression-free (PFS) and overall survival (OS) was evaluated using Kaplan–Meier survival estimates and Cox regression. Results: The overall median follow-up was 19 months from MET-PET. Recurrence patients (38/67) had higher SUVmax (p = 0.001), SUVmean (p = 0.002) and T/B (p < 0.001); deceased patients (16/67) showed higher SUVmax (p = 0.03), SUVmean (p = 0.03) and T/B (p = 0.006). All static parameters were associated with PFS (all p < 0.001); T/B was associated with OS (p = 0.031). Regarding kinetic analyses, recurrence (27/46) and deceased (14/46) patients had higher SUVmaxTTP (p = 0.02, p = 0.01, respectively). SUVmaxTTP was the only dynamic parameter associated with PFS (p = 0.02) and OS (p = 0.006). At univariate analysis, SUVmax, SUVmean, T/B and SUVmaxTTP were predictive for PFS (all p < 0.05); SUVmaxTTP was predictive for OS (p = 0.02). At multivariate analysis, SUVmaxTTP remained significant for PFS (p = 0.03). Conclusion: Semiquantitative parameters and SUVmaxTTP were associated with clinical outcomes in patients with suspected glioma recurrence. Dynamic PET-CT acquisition, with static and kinetic parameters, can be a valuable non-invasive prognostic marker, identifying patients with worse prognosis who require personalised therapy.

P05.04 Reradiation by reccurent gliomas with VMAT (Volumetric Modulated Arc Therapy) technique- survival benefit

BACKGROUND Patients who have been treated with reirradiation for recurrent glioma reported survival benefits. Limited data are available for the outcomes after fractionated re-irradiation. This study aims to investigate whether re-irradiation of recurrent glioma with 45Gy dose can increase the overall survival of patients. MATERIAL AND METHODS A retrospective analysis of 35 patients re-irradiated for high-grade glioma recurrence between 2012 and 2020 was performed. All included patients met the following criteria: a) histopathological confirmation of primary brain cancer at initial diagnosis; b) a history of initial primary radiation; c) histological and/or imaging modality confirmation of recurrence. Outcome metrics included overall survival, prognostic factors for survival, and treatment-related toxicity. RESULTS After the end of re-irradiation the median overall survival was 11 months (95% confidence interval, 7–14 months). From the patients evaluated in the current study after the end of re-irradiation the progression free survival was 6 months (3.8 - 8 months) while after the end of first radiation was 13 months (8 - 17.9 months). Our findings suggest that re-irradiation might prolong survival rates. CONCLUSION Recurrent Glioblastoma WHO IV is associated with a median overall survival of less than a year and the majority of patients have profound tumor-related symptoms.The results of this study suggest that re-irradiation may prolong the overall survival.