CBIO-28. IDENTIFYING THE ROLE OF MISMATCH REPAIR IN TEMOZOLOMIDE-INDUCED ATR ACTIVATION FOR MGMT-METHYLATED GLIOBLASTOMA MULTIFORME

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi32-vi33
Author(s):  
Sachita Ganesa ◽  
Amrita Sule ◽  
Ranjini Sundaram ◽  
Ranjit Bindra
Keyword(s):  
Glioblastoma Multiforme ◽  
Cell Line ◽  
Mismatch Repair ◽  
Methylation Status ◽  
Gene Promoter ◽  
Mgmt Gene ◽  
Mgmt Promoter ◽  
Atr Activation ◽  
Mmr Proteins

Abstract The methylation status of the O6-methyl guanine methyltransferase (MGMT) gene promoter is a prognostic biomarker for treatment with the alkylator, temozolomide (TMZ) in many solid tumors including gliomas and colorectal cancers. It is well established that patients with a methylated MGMT promoter (MGMT-) who are treated with the TMZ have a better overall survival than patients with an unmethylated MGMT promoter (MGMT+). The enzyme produced by the MGMT gene is responsible for removing cytotoxic O6-methylguanine (O6-meG) lesions formed by TMZ. In the MGMT- setting, the O6-meG lesion activates the mismatch repair (MMR) pathway which functions to remove the damage. Published work from our group reported differential activation of the ataxia telangiectasia and RAD3 related protein (ATR) in MGMT- and MGMT+ glioblastoma multiforme (GBM) cells in response to TMZ treatment, as demonstrated through the phosphorylation of CHK1. Though it is known that MMR proteins are involved in ATR activation, the specific MMR proteins required for ATR activation by TMZ-induced alkyl lesions remain unknown in the MGMT- setting. Here, we demonstrate that specific mismatch repair proteins, including MSH2, MSH6, and PMS2 play a role in ATR activation in the presence of O6-meG lesions. We show that there is potent synergy with ATRi and TMZ in the MGMT- MMR- proficient GBM cell line, which is abrogated in an shMMR MGMT- GBM cell line. Additionally, we observe decreased levels of pCHK1 in the shMMR MGMT- setting compared to the MGMT- MMR-proficient cells, suggesting that MMR is integral in the activation of ATR upon TMZ treatment. Mechanistic understanding of how the MMR system is involved in ATR activation by TMZ can ultimately be exploited for therapeutic gain.

scholarly journals CBIO-14. ELUCIDATING THE MECHANISM OF TEMOZOLOMIDE-INDUCED ATR ACTIVATION IN MGMT-METHYLATED GLIOBLASTOMA MULTIFORME

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii18-ii18
Author(s):  
Sachita Ganesa ◽  
Amrita Sule ◽  
Ranjini Sundaram ◽  
Ranjit Bindra
Keyword(s):  
Glioblastoma Multiforme ◽  
Cell Line ◽  
Potential Role ◽  
Standard Of Care ◽  
Related Protein ◽  
Current Standard ◽  
Mgmt Promoter ◽  
Atr Activation ◽  
Methylated Mgmt Promoter ◽  
Mmr Proteins

Abstract Glioblastoma multiforme (GBM) is an aggressive, malignant brain tumor in adults. The current standard of care for GBM is surgical resection, radiation therapy and chemotherapy with temozolomide (TMZ). It is well established that GBM patients with a methylated MGMT promoter (MGMT-) who are treated with TMZ have a better overall survival than patients with an unmethylated MGMT promoter (MGMT+). The enzyme produced by the MGMT gene is responsible for removing cytotoxic O6-methylguanine (O6-meG) lesions formed by TMZ. In the MGMT- setting, the O6-meG lesion activates the mismatch repair (MMR) pathway which functions to remove the damage. Published work from our group reported differential activation of the ataxia telangiectasia and RAD3 related protein (ATR) in MGMT- and MGMT+ GBM cells in response to TMZ treatment, as demonstrated through the phosphorylation of CHK1. It is known that MMR proteins are involved in ATR activation, however, this project aims to unravel the specific MMR proteins required for ATR activation by TMZ-induced alkyl lesions. To accomplish this, we treated an shMSH2 MGMT- GBM cell line with TMZ and an ATR inhibitor (ATRi) compared to treatment in an MSH2-proficient MGMT- GBM cell line. We observed decreased cell death in the shMSH2 setting compared to the MSH2-proficient cells, suggesting that MSH2 is integral in the activation of ATR upon TMZ treatment in the MGMT- setting. This study elucidates a potential role for MSH2 in ATR activation. Mechanistic understanding of how the MMR system is involved in ATR activation by TMZ can ultimately be exploited for therapeutic gain in the treatment of patients with GBM.

scholarly journals MPTH-14PROGNOSTIC ROLE OF METHYLATION STATUS OF MGMT PROMOTER ON GLIOBLASTOMA PATIENTS ESTIMATED QUANTITATIVELY BY PYROSEQUENCING

2015 ◽  
Vol 17 (suppl 5) ◽  
pp. v141.1-v141
Author(s):  
Dae Cheol Kim ◽  
Young Jin Song ◽  
Eun Hee Lee ◽  
Ki Uk Kim ◽  
Young Zoon Kim
Keyword(s):  
Methylation Status ◽  
Mgmt Promoter

MGMT methylation in newly-diagnosed glioblastoma multiforme (GBM): From the S0001 phase III study of radiation therapy (RT) and O6-benzylguanine, (O6BG) plus BCNU versus RT and BCNU alone for newly diagnosed GBM

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 1512-1512 ◽  
Author(s):  
D. T. Blumenthal ◽  
M. Wade ◽  
C. J. Rankin ◽  
F. Fitzpatrick ◽  
K. Stelzer ◽  
...  
Keyword(s):  
Glioblastoma Multiforme ◽  
Median Survival ◽  
Promoter Methylation ◽  
Promoter Region ◽  
Alkylating Agents ◽  
Methylation Status ◽  
Phase Iii ◽  
Newly Diagnosed ◽  
Tissue Samples ◽  
Mgmt Promoter

1512 Background: Glioblastoma multiforme (GBM) is a high grade primary brain neoplasm associated with a median survival of less than a year. Historically, one-third of patients seem to benefit from treatment with alkylating chemotherapy. This minority may correspond to a population with decreased levels of active O6-methylguanine- methyltransferase enzyme (MGMT). MGMT repairs tumor DNA damaged by chemotherapy, allowing continued replication after exposure to treatment. Patients with low tumor MGMT activity may be more likely to respond to alkylating treatment. Hypermethylation of the MGMT promoter region leads to decreased transcription of the enzyme and is associated with improved outcome in GBM patients treated with radiation and alkylating chemotherapy. Methods: We studied a patient cohort with newly diagnosed GBM registered on Southwest Oncology Group protocol S0001, a phase III randomized, two arm clinical trial investigating an inhibitor of MGMT (O6-benzylguanine, O6BG). Both groups received standard radiation and BCNU (carmustine). The experimental group additionally received O6BG. We determined polymerase chain reaction (PCR) methylation status of the promoter region of MGMT in 88 patients with adequate tissue samples. In 41 cases, we were able to obtain successful PCR results. Results: 28 of 41 samples (68%) were found to be unmethylated and 13 of 41 (32%, 95% c. i. 18% to 50%) were methylated. Patients with methylated MGMT had a median survival of 12.6 months (95% c.i. of 7.8–15.8 months). Patients with unmethylated MGMT had a median survival of 10.6 months (95% c.i. of 8.7–12.0 months). Median progression-free survivals were 4.5 and 3.1 months respectively, for the methylated and unmethylated groups. Conclusions: This result is consistent with prior studies which showed that approximately two-thirds of patients express MGMT, and accordingly, are resistant to alkylating agents. The subgroup of patients without promoter methylation may be more likely to benefit from treatment with O6BG. Analysis of MGMT promoter methylation status per study treatment group, and correlation with median survival and progression-free survival will be presented. No significant financial relationships to disclose.

scholarly journals exo1-Dependent Mutator Mutations: Model System for Studying Functional Interactions in Mismatch Repair

2001 ◽  
Vol 21 (15) ◽  
pp. 5142-5155 ◽  
Author(s):  
Neelam S. Amin ◽  
My-Nga Nguyen ◽  
Scott Oh ◽  
Richard D. Kolodner
Keyword(s):  
Mismatch Repair ◽  
Copy Number ◽  
Model System ◽  
Mutation Rates ◽  
Binding Region ◽  
Functional Interactions ◽  
Interaction Regions ◽  
Overexpressed Gene ◽  
Mmr Proteins

ABSTRACT EXO1 interacts with MSH2 and MLH1 and has been proposed to be a redundant exonuclease that functions in mismatch repair (MMR). To better understand the role of EXO1 in mismatch repair, a genetic screen was performed to identify mutations that increase the mutation rates caused by weak mutator mutations such as exo1Δ andpms1-A130V mutations. In a screen starting with anexo1 mutation, exo1-dependent mutator mutations were obtained in MLH1, PMS1, MSH2, MSH3, POL30 (PCNA),POL32, and RNR1, whereas starting with the weakpms1 allele pms1-A130V,pms1-dependent mutator mutations were identified inMLH1, MSH2, MSH3, MSH6, and EXO1. These mutations only cause weak MMR defects as single mutants but cause strong MMR defects when combined with each other. Most of the mutations obtained caused amino acid substitutions in MLH1 or PMS1, and these clustered in either the ATP-binding region or the MLH1-PMS1 interaction regions of these proteins. The mutations showed two other types of interactions: specific pairs of mutations showed unlinked noncomplementation in diploid strains, and the defect caused by pairs of mutations could be suppressed by high-copy-number expression of a third gene, an effect that showed allele and overexpressed gene specificity. These results support a model in which EXO1 plays a structural role in MMR and stabilizes multiprotein complexes containing a number of MMR proteins. A similar role is proposed for PCNA based on the data presented.

scholarly journals Favorable role of IDH1/2 mutations aided with MGMT promoter gene methylation in the outcome of patients with malignant glioma

2020 ◽  
pp. FSO663
Author(s):  
Arshad A Pandith ◽  
Iqbal Qasim ◽  
Shahid M Baba ◽  
Aabid Koul ◽  
Wani Zahoor ◽  
...  
Keyword(s):  
Promoter Methylation ◽  
Gene Promoter ◽  
Mgmt Promoter Methylation ◽  
Mgmt Methylation ◽  
Gene Methylation ◽  
Specific Pcr ◽  
Mgmt Promoter ◽  
Promoter Gene ◽  
Prognostic Outcome

Aim: The implications of molecular biomarkers IDH1/2 mutations and MGMT gene promoter methylation were evaluated for prognostic outcome of glioma patients. Materials & methods: Glioma cases were analyzed for IDH1/2 mutations and MGMT promoter methylation by DNA sequencing and methylation-specific PCR, respectively. Results: Mutations found in IDH1/2 genes totaled 63.4% (N = 40) wherein IDH1 mutations were significantly associated with oligidendrioglioma (p = 0.005) and astrocytoma (p = 0.0002). IDH1 mutants presented more, 60.5% in MGMT promoter-methylated cases (p = 0.03). IDH1 mutant cases had better survival for glioblastoma and oligodendrioglioma (log-rank p = 0.01). Multivariate analysis confirmed better survival in MGMT methylation carriers (hazard ratio [HR]: 0.59; p = 0.031). Combination of both biomarkers showed better prognosis on temozolomide (p < 0.05). Conclusion: IDH1/2 mutations proved independent prognostic factors in glioma and associated with MGMT methylation for better survival.

Phase II Study of Avelumab in Patients With Mismatch Repair Deficient and Mismatch Repair Proficient Recurrent/Persistent Endometrial Cancer

2019 ◽  
Vol 37 (30) ◽  
pp. 2786-2794 ◽  
Author(s):  
Panagiotis A. Konstantinopoulos ◽  
Weixiu Luo ◽  
Joyce F. Liu ◽  
Doga C. Gulhan ◽  
Carolyn Krasner ◽  
...  
Keyword(s):  
Endometrial Cancer ◽  
Mismatch Repair ◽  
Phase Ii ◽  
Phase Ii Study ◽  
Objective Response ◽  
Progression Free Survival ◽  
Complete Response ◽  
Immune Checkpoint Blockade ◽  
Mmr Proteins

PURPOSE Despite the tissue-agnostic approval of pembrolizumab in mismatch repair deficient (MMRD) solid tumors, important unanswered questions remain about the role of immune checkpoint blockade in mismatch repair–proficient (MMRP) and –deficient endometrial cancer (EC). METHODS This phase II study evaluated the PD-L1 inhibitor avelumab in two cohorts of patients with EC: (1) MMRD/ POLE (polymerase ε) cohort, as defined by immunohistochemical (IHC) loss of expression of one or more mismatch repair (MMR) proteins and/or documented mutation in the exonuclease domain of POLE; and (2) MMRP cohort with normal IHC expression of all MMR proteins. Coprimary end points were objective response (OR) and progression-free survival at 6 months (PFS6). Avelumab 10 mg/kg intravenously was administered every 2 weeks until progression or unacceptable toxicity. RESULTS Thirty-three patients were enrolled. No patient with POLE-mutated tumor was enrolled in the MMRD cohort, and all MMRP tumors were not POLE-mutated. The MMRP cohort was closed at the first stage because of futility: Only one of 16 patients exhibited both OR and PFS6 responses. The MMRD cohort met the predefined primary end point of four ORs after accrual of only 17 patients; of 15 patients who initiated avelumab, four exhibited OR (one complete response, three partial responses; OR rate, 26.7%; 95% CI, 7.8% to 55.1%) and six (including all four ORs) PFS6 responses (PFS6, 40.0%; 95% CI, 16.3% to 66.7%), four of which are ongoing as of data cutoff date. Responses were observed in the absence of PD-L1 expression. IHC captured all cases of MMRD subsequently determined by polymerase chain reaction or genomically via targeted sequencing. CONCLUSION Avelumab exhibited promising activity in MMRD EC regardless of PD-L1 status. IHC for MMR assessment is a useful tool for patient selection. The activity of avelumab in MMRP/non- POLE–mutated ECs was low.

Phase I/IIa trial of cilengitide (EMD121974) and temozolomide with concomitant radiotherapy, followed by temozolomide and cilengitide maintenance therapy in patients (pts) with newly diagnosed glioblastoma (GBM)

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 2000-2000 ◽  
Author(s):  
R. Stupp ◽  
R. Goldbrunner ◽  
B. Neyns ◽  
U. Schlegel ◽  
P. Clement ◽  
...  
Keyword(s):  
Primary Endpoint ◽  
Dna Methyltransferase ◽  
Methylation Status ◽  
Tumor Resection ◽  
Gene Promoter ◽  
Progression Free Survival ◽  
Liver Function Tests ◽  
Mri Imaging ◽  
Mgmt Gene ◽  
Grade 3

2000 Background: To evaluate safety, toxicity, and efficacy of the combination of the cyclic RGD pentapeptide cilengitide (EMD121974), an inhibitor of integrins avβ3 and avβ5, in addition to standard temozolomide (TMZ) and radiotherapy (RT). Methods: 52 pts (PS 0–1: 92%, 2: 8%; median age 57 yrs) after tumor resection (n=43/83%) or biopsy (n= 9/17%) were treated with standard TMZ/RT (Stupp et al. NEJM 2005). In addition cilengitide (500 mg i.v., 2x/week) was started one week before TMZ/RT and given throughout for the duration of chemotherapy or until progression. The primary endpoint was progression free survival rate at 6 months (target: 65%). Pts were followed with MRI every 2 months. Histopathologic diagnosis and MRI imaging were independently reviewed, O6-Methylguanine- DNA methyltransferase (MGMT) promotor methylation status was assessed in 45 (86.5%) pts. Results: 46 pts (92%) completed RT, = 90% of concomitant TMZ was received by 42 pts and cilengitide by 45 pts. 20 pts (3 ongoing) completed 6 cycles of maintenance TMZ and cilengitide. Observed hematological grade 3 and 4 toxicities were: lymphopenia (28/52, 53.8%), thrombocytopenia (7/52 pt. 13.4%) and neutropenia (5/52, 9.6%). Treatment related non-hematologic grade 3/4 toxicities were reported for n=3/52 (5.7%) patients: constitutional symptoms (asthenia, fatigue, anorexia, n=3); elevated liver function tests (n=1), deep venous thrombosis and pulmonary embolism (n=1). One patient with a history of sigmoid diverticulosis experienced sigmoid perforation (grade 2). In total, 34/52 (65.4% [95% CI, 50.9–78.0%]) of the pts were progression free at 6 months. Pts with MGMT gene-promotor methylation in the tumor were more likely to reach 6 months PFS endpoint. Conclusions: The study reached its primary endpoint. The combination of the integrin inhibitor RGD peptide Cilengitide and TMZ/RT was well tolerated, PFS at 6 months is encouraging. MGMT gene promoter methylation correlates with outcome. At the time of ASCO, updated results and survival estimates after a minimum follow-up of at least 1 year will be available. [Table: see text]

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