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Pembrolizumab in MMR-Proficient Metastatic Colorectal Cancer Pharmacologically Primed to Trigger Hypermutation Status

ABSTRACT: In this study, MMRd metastatic colorectal cancer (mCRC) patients who failed standard therapies will undergo treatment with pembrolizumab, while RAS-extended mutated MMR-proficient mCRC patients will be tested for o6-methylguanine-DNA-methyltransferase (MGMT) expression (IHC) and then for MGMT promoter methylation. MGMT IHC-negative, promoter methylation positive patients will be treated with temozolomide (TMZ). Patients progressing under temozolomide will be tested for tumor mutational burden (TMB) and proceed to pembrolizumab if TMB is > 20 mutations/Mb. The primary study hypothesis is that tumors with acquired resistance to temozolomide become hypermutated and are sensitive to pembrolizumab.

DISEASE(S): Microsatellite Instability,Cancro Metastatico Al Colon Retto In Pazienti Con Mutazioni Ras,Colorectal Cancer Metastatic,Ras Mutated Metastatic Colorectal Cancer,Colorectal Neoplasms

PROVIDER: 2272487 | ecrin-mdr-crc |

REPOSITORIES: ECRIN MDR

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MGMT enhancer modulates glioma cell sensitivity to temozolomide through long-range regulations of multiple genes

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Combined bioinformatic and clinical assay uncovers resistance and susceptibility mechanisms of human glioblastomas to temozolomide and identifies new survival biomarkers outperforming MGMT promoter methylation

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MGMT genomic rearrangements contribute to chemotherapy resistance in gliomas

Project description:Temozolomide (TMZ) is an oral alkylating agent used for the treatment of glioblastoma and is now becoming a chemotherapeutic option in patients diagnosed with high-risk low-grade gliomas1. The O-6-methylguanine-DNA methyltransferase (MGMT) is responsible for the direct repair of the main TMZ-induced toxic DNA adduct, the O6-Methylguanine lesion. MGMT promoter hypermethylation is currently the only known biomarker for TMZ response in glioblastoma patients2. Here we show that a subset of recurrent gliomas carry MGMT genomic rearrangements that lead to MGMT overexpression, independently from changes in its promoter methylation. By leveraging the CRISPR/Cas9 technology we generated some of these MGMT rearrangements in glioma cells and demonstrated that they lead to TMZ resistance both in vitro and in vivo. Lastly we showed that such fusions can be detected in tumor-derived exosomes and could potentially represent an early detection marker of tumor recurrence in a subset of patients treated with TMZ.

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661b1868-1ffa-4101-a0ac-6eed395c92db - samples

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2022-08-20 | GSE207426 | GEO

5FU/LV, Irinotecan, Temozolomide and Bevacizumab for MGMT Silenced, Microsatellite Stable Metastatic Colorectal Cancer.

Project description:An upfront-intensified treatment combining all the three active cytotoxic agents in metastatic colorectal cancer (mCRC) including fluoropyrimidines, oxaliplatin, irinotecan (FOLFOXIRI) plus antiangiogenic blockade with bevacizumab significantly improved survival. No biomarkers are available for predicting sensitivity/resistance to single chemotherapeutic drugs, the simultaneous delivery of all active chemotherapeutic agents might overcome resistance to single drugs. Temozolomide has modest but non-negligible activity (about 10%) in chemo-refractory patients with MGMT methylated mCRC. The response rate to temozolomide-based therapy in pretreated patients is increased to up to 20% when restricting the focus on those with MGMT IHC-negative/MGMT methylated and MSS cancers. Clinical and preclinical synergy has been reported for combination of temozolomide with irinotecan and fluoropyrimidines. Temozolomide could be regarded as a "targeted" chemotherapy for patients with MSS and MGMT silenced tumors. In this subgroup of patients, an intensified triplet upfront regimen including temozolomide, fluoropyrimidines, irinotecan, associated with bevacizumab, could be a novel combination in molecularly super-selected mCRC patients. Moving from this, the investigators designed this open-label, monocentric, phase 1b study evaluating the safety of the combination regimen 5-fluorouracil, leucovorin, irinotecan, temozolomide and bevacizumab in patients with MGMT silenced and MSS mCRC. The study will consist in a dose-escalation assessment of the safety of the treatment in subjects with previously untreated MGMT silenced, MSS mCRC. A 3 + 3 design will be used to assess the maximum tolerated dose (MTD) or maximum tested dose of the combination FLIRT-bevacizumab.

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