Prognostic role and interaction of TERT promoter status, telomere length and MGMT promoter methylation in newly diagnosed IDH wild-type glioblastoma patients

BACKGROUND

The clinical relevance of promoter mutations and single nucleotide polymorphism rs2853669 of telomerase reverse transcriptase (TERT) and telomere length in patients with isocitrate dehydrogenase (IDH) wild-type glioblastoma (GBM) patients remains unclear. Moreover, some studies speculated that TERT promoter status might influence the prognostic role of O6-methylguanine DNA methyltransferase (MGMT) promoter methylation in newly diagnosed GBM. We carried out a large study to investigate their clinical impact and their interaction in newly diagnosed GBM patients.

PATIENTS AND METHODS

We included 273 newly diagnosed IDH wild-type GBM patients who started treatment at Veneto Institute of Oncology IOV - IRCCS (Padua, Italy) from December 2016 to January 2020. TERT promoter mutations (-124 C>T and -146 C>T) and SNP rs2853669 (-245 T>C), relative telomere length (RTL) and MGMT methylation status were retrospectively assessed in this prospective cohort of patients.

RESULTS

Median overall survival (OS) of 273 newly diagnosed IDH wild-type GBM patients was 15 months. TERT promoter was mutated in 80.2% of patients, and most had the rs2853669 single nucleotide polymorphism as T/T genotype (46.2%). Median RTL was 1.57 (interquartile range 1.13-2.32). MGMT promoter was methylated in 53.4% of cases. At multivariable analysis, RTL and TERT promoter mutations were not associated with OS or progression-free survival (PFS). Notably, patients C carrier of rs2853669 (C/C+C/T genotypes) showed a better PFS compared with those with the T/T genotype (hazard ratio 0.69, P = 0.007). In terms of OS and PFS, all interactions between MGMT, TERT and RTL and between TERT and rs2853669 genotype were not statistically significant.

CONCLUSIONS

Our findings suggest the presence of the C variant allele at the rs2853669 of the TERT promoter as an attractive independent prognostic biomarker of disease progression in IDH wild-type GBM patients. RTL and TERT promoter mutational status were not correlated to survival regardless of MGMT methylation status.

P18.05.A Bevacizumab in atypical and anaplastic meningiomas: the BEMEN study

Background

meningiomas are the most frequent primary brain tumours. The current standard treatment for atypical and anaplastic meningioma can include surgical resection and radiotherapy. Despite the high rate of relapse no systemic treatment is indicated. Few data are available regarding the effectiveness of bevacizumab (BEV) in this setting. We performed a retrospective analysis investigating the efficacy and safety of BEV in meningioma patients relapsed after receiving surgery and radiotherapy. Gene mutations were also collected

Material and Methods

we retrospectively analyzed patients treated with off-label BEV at the Veneto Institute of Oncology from July 2019 to February 2022. Major inclusion criteria were histologically-confirmed diagnosis of grade 2-3 meningioma (according to WHO 2016 classification), previous treatment with surgery and radiotherapy, no indication to further surgical reintervention or reirradiation, absence of major contraindications to the use of BEV. Data were estrapolated from local clinical records. Bevacizumab was administered at 10 or 5mg/Kg every 2 weeks (at physician’s discretion) until progressive disease/death or unacceptable toxicity. Kaplan-Meier curves were used to estimate the survival rate; CTCAE v 5.0 was used to estimate treatment-related toxicities; RANO criteria were used for radiological assessment; NGS Foundation One panel was used to examine molecular data

Results

the median follow up was 13 months (3-30 range). 26 patients were enrolled. Median age was 68 ys (29-84); male pts were 16 (61%); 61% (16 pts) with atypical meningioma, 38.5% (10 pts) with anaplastic meningioma; 27% (7 pts) had underwent 2 or more surgeries; 58% had had 2 or more RT treatments; 96.1% (25 pts) received <2 previous lines of systemic treatment. 77% (20 pts) and 23% (6) received BEV 10 and 5mg/Kg every 2 weeks, respectively. For 61% of patients (16 pts), NGS analyses were available; 62% (10 pts) harboured NF2 mutations (1 patient had a confirmed diagnosis of neurofibromatosis type 2), 23% (6 pts) CDKN2A/2B deletion, 11% (3 pts) PTEN mutation, 8% (2 pts) FGFR mutation, 8% (2 pts) JAK alteration. Overall survival (OS) rate was 82% and 62% at 6 and 12 months respectively; 6 months PFS rate was 83%. 4 patients showed PR, 11 SD, 6 PD, no patient had CR; 5 patients were not evaluable for response. Among evaluable patients the disease control rate (stability+response) was 71% and the objective response rate was 19%. Median PFS and OS were not reached19% (5 pts) experienced CTCAE grade 1 or 2 toxicity, mainly hypertension (4 pts); 1 patient experienced grade 3 hypertension.

Conclusion

BEV showed very promising activity in recurrent grade 2-3 meningioma. The treatment was well tolerated. BEV should be considered an optimal therapeutic option in this setting of meningioma patients. The NGS results might be useful in identifying targetable mutations in case of further recurrence

P02.02.A Next-generation sequencing (NGS) for identifying actionable molecular alterations in newly diagnosed and recurrent IDHwt-glioblastoma (GBM) patients: a large mono institutional experience

Background

NGS panels allow the identification of alterations within hundreds of cancer-related genes and can guide a personalized strategy in glioma treatment.

Material and Methods

From Nov 2019 to Jan 2022 at Veneto Institute of Oncology, Padua, Italy, a large cohort of IDHwt-GBM tissues was analyzed by NGS (FoundationOne®CDx). We identified all potential actionable molecular alterations at diagnosis and/or at recurrence. High tumor mutational burden (TMB) was defined as ≥10 mutations/megabase.

Results

We analyzed 429 IDHwt-GBM samples: NGS profile was available for 419 samples (97.7%); sample failures in 10 cases (2.3%). 351 (84%) and 68 (16%) GBM samples derived from surgery at diagnosis and recurrence, respectively. All patients received radiotherapy and/or temozolomide as first line therapy. Among all the analyzed samples, the most frequent actionable molecular alterations were: CDKN2A (57%), CDKN2B (53%), EGFR amplification (39%), EGFR mutation (24%), PTEN loss (27%), RB1 (23%), NF1 (18%), PIK3CA (18%), CDK4 (15%), MDM2 (10%), PDGFRA (8%), BRCA1-2 (7%), FGFR1-3 (7%), Myc (6%), JAK (6%), ROS1 (5%), METmut (2%), METampl (2%), BRAF V600E (2%). No NTRK1/2/3 druggable alterations were observed. High TMB was found in 18 samples. The incidence of alteration of EGFR (ampl/mut), RB1, PIK3CA was statistically different between the two subgroups of samples (Fisher test). To date, 10% of patients received a personalized treatment as compassionate use, off-label use or in clinical trials (9 Dabrafenib/Trametinib, 8 Alpelisib, 3 Erdafitinib, 2 Ipatasertib, 1 Alectinib, 1 Capmatinib, 1 Palbociclib, 1 Entrectinib, 1 Pamiparib). Activity analysis is still ongoing.

Conclusion

NGS is feasible in GBM samples. Potentially, a high rate of patients could receive a personalized treatment. The activity analysis is ongoing. However, the incidence of actionable molecular alterations may differ between diagnosis and recurrent GBM samples.

P11.20.A Correlation between thyroid function and regorafenib activity in recurrent IDH wild-type(IDHwt) glioblastoma(GBM) patients: a large monocentric study

Background

Glioblastoma is the most frequent CNS malignant tumor, with high aggressiveness and poor prognosis. Regorafenib has recently demonstrated promising activity in terms of survival in recurrent glioblastoma patients. The impact of thyroid function on regorafenib activity has alreasy described in in patients with other types of tumors. This study aimed to investigate the relationship between baseline thyroid variables (TSH, fT3, fT4, fT3/fT4 ratio) and survival in IDHwt GBM patients who were treated with regorafenib.

Material and Methods

We retrospectively evaluated all consecutive recurrent IDHwt GBM patients who were treated with regorafenib at the Veneto Institute of Oncology in Padua (Italy) for which baseline thyroid function assessment was available prior to starting regorafenib. Major inclusion criteria were: histological diagnosis of IDHwt glioblastoma, regorafenib as second-line treatment, basel thyroid values available.The relationships between baseline thyroid variables (TSH, fT3, fT4, fT3/fT4 ratio) and outcomes (PFS, OS) were investigated with Cox regression models, where thyroid variables were modeled with first order polynomial or restricted cubic splines.

Results

We enrolled 108 recurrent IDHwt glioblastoma patients treated with regorafenib at our center From November 2015 to January 2022: 70% were male and median age was 50 years old. All patients received post-surgical treatment with concomitant chemotherapy and subsequent temozolomide according to Stupp protocol as first-line therapy. 32 patients (30%) underwent a second surgery upon recurrence. From starting regorafenib the median follow-up was 7.3 months (IQR 4.0-12.7). MedianPFS was 2.2 months (95% CI 2.0 to 3.4), and PFS rate was 43-13-4% at 3-6-12ms, respectively. MedianOS was 10.4 months (95% CI 7.5 to 14.5), and OS rate was 92-70-46% at 3-6-12 months, respectively. Disease Control Rate (DCR) was 42.7%. Univariate analysis suggested that the relationship between PFS and baseline fT4 may be modelled with first order polynomial (linear term p=0.06, non-linear term p=0.61) and also suggested a non-linear relationship between PFS and baseline fT3/fT4 (linear term p=0.06, non-linear term p=0.04).When adjusting for major clinical confounding factors (age, ECOG PS, second surgery, MGMT), multivariate analysis identified that baseline fT4 (as a continuous variable) is an independent risk factor for PFS (HR 1.09, 95% CI 1.02 to 1.17; p=0.02). We did not find any statistically significant associations between all baseline thyroid variables with OS and response.

Conclusion

Our study demonstrated fT4 value to be a predictive biomarker of PFS in recurrent glioblastoma patients treated with regorafenib. No correlation was showed between baseline thyroid function and survival.

P17.06.B Different dosage of bevacizumab treatment in recurrent IDHwt glioblastoma/IDHmut grade 4 astrocytoma and its impact on outcome

Background

Angiogenesis is one of the most distinctive hallmarks of glioblastoma (GBM). Although bevacizumab did not show to improve overall survival in phase 3 trials, it was approved by FDA and is often prescribed as off-label therapy in the recurrent clinical setting. The aim of this study is to evaluate the difference in terms of survival and safety between the 5 mg/m2 and 10 mg/m2 bevacizumab schedule in recurrent GBM.

Material and methods

All pts treated at Veneto Institute of Oncology from May 2013 to March 2022 were retrospectively reviewed. Major inclusion criteria were: histologically confirmed diagnosis of IDHwt GBM/IDHmut grade 4 astrocytoma (according to the WHO 2021 classification), relapse after first or subsequent line of therapy, treatment with bevacizumab at 5 mg/m2 or/and 10 mg/m2 every 2 weeks until progression/death or unacceptable toxicity. Bevacizumab was administered as off-label therapy. The treatment schedule was at physician’s discretion. RANO criteria and CTCAE v5.0 were used for response and toxicity assessment.

Results

81 pts were enrolled. From starting bevacizumab the median follow-up was 10.9ms [95% CI 9.8-14.0] and median age was 53ys (range 18-81). 33 (41%) pts received the 5 mg/m2 schedule. Among them, 2 (6%) were IDHmut grade 4, 8 (24%) had ≥65ys and ECOG-PS was 0-1 in 16 (48%) and ≥2 in 17 (51%), respectively. MGMT was methylated in 15 of 30 (50%) evaluable pts. Median number of prior lines of treatment was 2 (range 1-4) and 30% of pts received bevacizumab at first recurrence. 28 (84.9%) pts were evaluable for response: 7 (21%) and 5 (15%) showed PR and SD. 48 pts received the 10 mg/m2 schedule: 5 (10%) were IDHmut grade 4 astrocytoma; 29 (60%) had an ECOG-PS of 0 or 1 and 4 (8%) had ≥65ys, MGMT was methylated in 20 of 44 (45%) evaluable pts. 36 (75%) pts received bevacizumab beyond the second line of therapy. 46 (96%) pts were evaluable for response: 6 (12%) had PR, 19 (39%) SD. mOS from the start of bevacizumab was 7.3ms (95% CI 4.3-6.4), mPFS was 4.4ms [95% CI 3.7 - 6.4]. At univariate analysis, pts who received the 5 mg/m2 or the 10 mg/m2 schedule had a mOS of 5.4 and 7.7ms (p=0.08); mOS for pts with ECOG-PS < or ≥2 was 9.0 and 5.4ms (p=0.04) while mOS for pts with <2 or ≥2 lines of therapy was 4.7 and 7.7ms (p=0.056). Age and type of the tumor were not statistically significant. At multivariate analysis, MGMT methylated status was the only factor statistically associated with OS (HR=0.48, 95% CI, p=0.002) and PFS (HR=0.33, 95% CI, p=0.001), while a number of prior lines of therapy ≥2 (HR=2.07, 95% CI, p=0.02) was significantly associated only with PFS. Grade 3-4 most common adverse events were hypertension (18%) in pts treated with 5 mg/m2 and hypertension (16%) and proteinuria (2%) in pts treated with 10 mg/m2.

Conclusions

Bevacizumab treatment with a dosage of 5 mg/m2 and 10 mg/m2 seems to give comparable outcome in terms of survival in recurrent GBM pts. No difference was demonstrated for safety.

P17.07.A Metronomic temozolomide therapy in heavily pretreated patients with recurrent glioblastoma: a large mono-institutional retrospective study

Background

Glioblastoma (GBM) is the most common and aggressive primary brain cancer. Despite advances in surgical and first-line treatment, all pts relapse. The aim of this study is to evaluate the benefit of metronomic Temozolomide (mTMZ) for recurrent GBM.

Material and Methods

All pts treated at Veneto Institute of Oncology from September 2013 to March 2021 were retrospectively reviewed. Major inclusion criteria were: first-line therapy with Stupp protocol, relapse after first or subsequent line of therapy, treatment with mTMZ schedule (50mg/m2 continuously), hystologically confirmed diagnosis of GBM. RANO criteria and CTCAE v 5.0 were used for response and toxicity assessment.

Results

120pts were enrolled. Median follow-up was 15.6ms. Median age was 59ys (range 18-81), ECOG-PS was 0-2 in 107pts (89%) and 3 in 11 (9%). MGMT was methylated and IDH mutated in 66 of 105 (62%) and in 9 of 106 (8%) evaluable pts, respectively. Median number of prior lines of treatment was 2 (range 1-7) and 41% of pts received the therapy beyond the third line. Median time between the last standard maintenance TMZ (sTMZ) cycle and the mTMZ administration was 6ms (range 1-50) and 40% of pts started mTMZ after 3ms from sTMZ. All pts were evaluable for response: 3 (2%) and 48 (40%) showed PR and SD. mOS from the start of mTMZ was 5.4ms (95% CI 4.3-6.4), mPFS was 2.6ms (95% CI 2.3-2.8). At univariate analysis, MGMTmet and MGMTunmet pts had a mOS of 5.6 and 4.4ms (p=0.03); mOS for patients with ECOG-PS > or ≤2 was 2.3 and 6.0ms (p<0.001); number of prior lines of therapies, time between sTMZ and mTMZ and age were not significant. At multivariate analysis, MGMT methylated status (HR=2.3, 95% CI, p=0.004) and ECOG-PS (HR=0.5, 95% CI, p=0.017) remained statistically significant for PFS, while ECOG-PS (HR=0.4, 95% CI, p=0.001) was the only factor significantly associated with OS. The most common grade 3-4 hematologic toxicities were lymphopenia (10%) and thrombocytopenia (3%). Grade 3-4 nonhematologic toxicities were uncommon.

Conclusion

Rechallenge with mTMZ can be a well tolerated treatment option for recurrent GBM, even in heavily pretreated pts. Pts with MGMTmet and good ECOG-PS might report the major benefit.

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

P14.19 Regorafenib in recurrent glioblastoma patients: a large real-life experience

BACKGROUND

Regorafenib (REG), an oral multikinase inhibitor of angiogenic, stromal, and oncogenic receptor tyrosine kinases showed encouraging benefit in recurrent GBM patients enrolled in the randomized, phase 2 REGOMA trial. We investigated the clinical outcome and safety of REG in a real-life population of recurrent glioblastoma patients treated at Veneto Institute of Oncology as off-label use.

MATERIAL AND METHODS

Patients receiving REG at Veneto Institute of Oncology (Padua, Italy) were entered prospectively on a clinical database. Data were retrospectively analyzed. The primary endpoints of the study were overall survival (OS) and safety. The major inclusion criteria were: histologically confirmed diagnosis of GBM, disease progression as defined by RANO criteria after surgery followed by radiochemotherapy with temozolomide, ECOG PS ≤ 2; PTS with ≥ 2 prior lines of therapy were excluded. According to original schedule, patients received REG 160 mg once daily for the first 3 weeks of each 4-week cycle until disease progression, death, unacceptable toxicity, or consent withdrawal. Kaplan-Meier method was used to estimate the survival curves, RANO criteria for radiological assessment, CTCAE v5.0 for drug related adverse events.

RESULTS

From February 2018 to September 2020, 54 consecutive patients were treated with REG and enrolled in this study: median age was 56, ECOG PS 0–1 in 91% of patients, MGMTmet in 53%, second surgery at the time of relapse were performed in 30% of enrolled patient, 41% of patients underwent steroids at baseline. At the time of analysis, median follow-up was 11.1 ms, 30 PTS (56%) had died and 50 PTS (93%) had progressed. Median OS was 10.2 ms (95%CI, 6.4–13.9), 12m-OS was 43%; median PFS was 2.3ms (95%CI, 1.3–3.3) and 6m-PFS was 18%. All patients were evaluable for response: disease control rate (DCR) was 46.3%; stable disease was reported in 38.8% and partial response in 7.4%. Age, MGMT status and corticosteroid use at baseline were not statistically significant on multivariate analysis for OS. Grade 3 drug-related adverse events (AEs) occurred in 10 patients (18%) and the most frequent were hand-foot skin reaction, asthenia and increased lipase and transaminases; 1 PT (2%) reported a grade 4 AE (rash maculo-papular). AEs led to REG dose reductions in 37% of patients and, it was permanently discontinued in 5%. No death was considered to be drug-related.

CONCLUSION

We reported a large, mono-institutional “real world” experience of REG in recurrent glioblastoma patients. Overall, results are close to those reported in REGOMA trial although, we showed a longer OS. Toxicity was moderate and manageable. Encouraging clinical benefits of REG in recurrent GBM population were confirmed.