Prospective Biomarker Study in Newly Diagnosed Glioblastoma: Cyto-C Clinical Trial

Background Glioblastoma (GBM) has a 5-year survival rate of 3–5%. GBM treatment includes maximal resection followed by radiotherapy with concomitant and adjuvant temozolomide (TMZ). Cytochrome c oxidase (CcO) is a mitochondrial enzyme involved in the mechanism of resistance to TMZ. In a prior retrospective trial, CcO activity in GBMs inversely correlated with clinical outcome. The current Cyto-C study was designed to prospectively evaluate and validate the prognostic value of tumor CcO activity in patients with newly diagnosed primary GBM, and compared to the known prognostic value of MGMT promoter methylation status. Methods This multi-institutional, blinded, prospective biomarker study enrolled 152 patients with newly diagnosed GBM who were to undergo surgical resection and would be candidates for standard of care. The primary end point was overall survival time (OS), and the secondary end point was progression-free survival time (PFS). Tumor CcO activity and MGMT promoter methylation status were assayed in a centralized laboratory. Results OS and PFS did not differ by high or low tumor CcO activity, and the prognostic validity of MGMT promoter methylation was confirmed. Notably, a planned exploratory analysis suggested that the combination of low CcO activity and MGMT promoter methylation in tumors may be predictive of long-term survival. Conclusions Tumor CcO activity alone was not confirmed as a prognostic marker in GBM patients. However, the combination of low CcO activity and methylated MGMT promoter may reveal a sub-group of GBM patients with improved long term survival that warrants further evaluation. Our work also demonstrates the importance of performing large, multi-institutional, prospective studies to validate biomarkers. We also discuss lessons learned in assembling such studies.

Artificial intelligence for early prediction of treatment response in glioblastoma

Aims Treatment response assessment in glioblastoma is challenging. Patients routinely undergo conventional magnetic resonance imaging (MRI), but it has a low diagnostic accuracy for distinguishing between true progression (tPD) and pseudoprogression (psPD) in the early post-chemoradiotherapy time period due to similar imaging appearances. The aim of this study was to use artificial intelligence (AI) on imaging data, clinical characteristics and molecular information within machine learning models, to distinguish between and predict early tPD from psPD in patients with glioblastoma. Method The study involved retrospective analysis of patients with newly-diagnosed glioblastoma over a 3.5 year period (n=340), undergoing surgery and standard chemoradiotherapy treatment, with an increase in contrast-enhancing disease on the baseline MRI study 4-6 weeks post-chemoradiotherapy. Studies had contrast-enhanced T1-weighted imaging (CE-T1WI), T2-weighted imaging (T2WI) and apparent diffusion coefficient (ADC) sequences, acquired at 1.5 Tesla with 6-months follow-up to determine the reference standard outcome. 76 patients (mean age 55 years, range 18-76 years, 39% female, 46 tPD, 30 psPD) were included. Machine learning models utilised information from clinical characteristics (age, gender, resection extent, performance status), O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status and 307 quantitative imaging features; extracted from baseline study CE-T1WI/ADC and T2WI sequences using semi-automatically segmented enhancing disease and perilesional oedema masks respectively. Feature selection was performed within bootstrapped cross-validated recursive feature elimination with a random forest algorithm and Naïve Bayes five-fold cross-validation to validate the final model. Results Treatment response assessment based on the standard-of-care reports by clinical neuroradiologists showed an accuracy of 33% (sensitivity/specificity 52%/3%) to distinguish between tPD and psPD from the early post-treatment MRI study at 4-6 weeks. Machine learning-based models based on clinical and molecular features alone demonstrated an AUC of 0.66 and models using radiomic features alone from the early post-treatment MRI demonstrated an AUC of 0.46-0.69 depending on the feature and mask subset. A combined clinico-radiomic model utilising top common features demonstrated an AUC of 0.80 and an accuracy of 74% (sensitivity/specificity 78%/67%). The features in the final model were age, MGMT promoter methylation status, two shape-based features from the enhancing disease mask (elongation and sphericity), three radiomic features from the enhancing disease mask on ADC (kurtosis, correlation, contrast) and one radiomic feature from the perilesional oedema mask on T2WI (dependence entropy). Conclusion Current standard-of-care glioblastoma treatment response assessment imaging has limitations. In this study, the use of AI through a machine learning-based approach incorporating clinical characteristics and MGMT promoter methylation status with quantitative radiomic features from standard MRI sequences at early 4-6 weeks post-treatment imaging showed the best model performance and a higher accuracy to distinguish between tPD and psPD for early prediction of glioblastoma treatment response.

PL02.5.A 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 IDHwildtype glioblastoma (GBM) patients (PTS): A large mono-institutional study

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 monoinstitutional study to better investigate their impact and their interaction on clinical outcomes MATERIAL AND 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 CONCLUSION 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

Elderly glioblastoma patients: Survival analysis according adjuvant therapy and tumor molecular analysis.

e14046 Background: Glioblastoma (GBM) grade IV represents the most frequent and aggressive primary brain tumor. Despite complete surgical resection, GBM infiltrative potential leads to local recurrence rates of around 100%. Standard treatment with adjuvant chemotherapy (CT) and radiotherapy (RT) according Stupp regimen aims to reduce relapse and improve survival, but toxicities associated with these therapies represent a problem in elderly unfit population. O6-Methylguanine-DNA methyltransferase (MGMT) promoter methylation status has been recognized as a predictive factor of response to alkylating agents as temozolomide. We aimed to compare overall survival (OS) results in elderly GBM patients according with MGMT promoter status and systemic treatment after surgery. Methods: We performed a database from the information available from RETSINE (Registro Nacional Español de Tumores de Sistema Nervioso Central). We selected ≥ 65 years GBM diagnosed patients. Relevant information was tumor MGMT promoter methylation status and adjuvant CT and/or RT after resection. Kaplan- Meier analysis was performed. Selected outcome was OS and 95% confidence intervals (CI) and p value < 0.05 were used as measures of statistical significance. Results: We identified 400 eligible GBM patients diagnosed ≥ 65 years (male = 232- 58%; female = 168-42% ). According tumor MGMT status: 125 (31.3%) methylated tumors, 115 (28.7%) non methylated and 160 unknown MGMT status. Included population median age was 72 years (65-88 years). Median global population OS was 7.93 months (IC95% 6.84-9.02). Survival analysis showed better OS for methylated tumors group, median OS 7.33 (IC 95%4.1-10.56) vs. unmethylated OS 7.06 (IC95% 4.9-9.1) (p = 0.021). Survival analysis in methylated patients showed improved OS in patients treated with RT + CT vs. no adjuvant therapy. Median OS for methylated patients treated with CT + RT was 11.46m (IC95%7.6-15.9) vs 9.6 months with only RT(IC95%3.67-7.26) and 2.1m with no treatment (IC95%2.03-3.76) p = 0,00. Unmethylated patients median OS was 9.36m (IC95%3.67-7.26) for RT-CT, 5.4 m (IC95%2.37-8.42) for RT only and 2.76 (IC95% 1.37-4.15) for no treatment p = 0.00. Conclusions: Elderly GBM patients have similar treatment options than young patients and comprise surgical resection, RT and alkylating CT with temozolomide. Comorbidities and performance status have relevant implications in elderly population treatment decisions. The MGMT promoter status has been described as a prognostic and predictive marker of response to temozolomide. In our series both methylated and unmethylated patients can benefit with systemic treatment.

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.

The MGMT (O6-methylguanine–DNA methyltransferase) promotes methylation and clinical outcomes of salvage temozolomide and irinotecan chemotherapy in progressive Ewing sarcoma: A preliminary report.

e23507 Background: There remains an unmet need to identify prognostic and predictive molecular biomarkers in advance Ewing sarcoma (ES). We sought to assess the influence of MGMT promoter methylation status on response rate, time to progression (TTP), and overall survival (OS) following salvage irinotecan and temozolomide (IT) chemotherapy. Methods: Data of advanced ES patients, treated with IT chemotherapy from Jan, 2014 to Jan, 2020 were retrospectively collected. Patients were required to have previously received and progressed after vincristine, doxorubicin, and cyclophosphamide alternating with ifosfamide and etoposide (VDC-IE). MGMT promoter methylation status was assessed by Methylation Sensitive Restriction Enzyme quantitative-PCR (MSRE-qPCR) on non-decalcified Formalin-fixed paraffin embedded (FFPE) tissue using internally developed primers and the OneStep qMethyl Kit (ZYMO RESEARCH CORP). Responses were assessed by response evaluation criteria in solid tumors (RECIST v. 1.1). TTP and OS were assessed by the Kaplan-Meier method. Survival comparisons were performed by the Log-rank test. Results: Herein, we present data of the preliminary analysis of the first 18 patients who underwent MGMT promoter methylation testing. Patients had a median age of 18 years (range: 5-34 years), and were predominantly male ( n=11; 61%). The primary tumor was located in the pelvis in 9 patients (50%), femur in 3 (17%), tibia in 2 (11%), kidney in 2 (11%), chest wall in one (6%), and scapula in one patient (6%). IT was given in a second ( n=15) or third-line setting ( n=3). At the time of initiation of IT, 13 patients (72%) had distant metastasis, and 5 (28%) had unresectable local progression in the pelvis ( n=4) or chest wall ( n=1). The mean percentage of MGMT promoter methylation was 29% (range: 3-98%). Five patients (28%) had methylated MGMT promoter, whereas the remaining had partially methylated ( n=6; 33%) or unmethylated ( n=7;39%) promoter. Five patients (28%) had objective response, with no observed difference according to MGMT promoter methylation ( p=0.58 for comparison between methylated and unmethylated/ partially methylated). Median TTP was 4.9 and 2.2 months for patients with methylated and partially methylated/ unmethylated MGMT respectively; p=0.76. The corresponding median OS was 69.4 and 14.3 months in favor of the methylated group; p=0.3. Conclusions: This preliminary data suggests a possible prognostic role for MGMT promoter methylation, with a markedly extended median OS for the methylated group. Nevertheless, the median OS difference did not reach statistical significance in this preliminary analysis. We plan to report data of the final analysis after finalizing MGMT testing for the rest of our study patients.