EPCO-03. GLIOMA ONCOGENESIS IN THE CONSTITUTIONAL MISMATCH REPAIR DEFICIENCY (CMMRD) SYNDROME

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi1-vi2
Author(s):  
Léa Guerrini-Rousseau ◽  
Jane Merlevede ◽  
Philippe Denizeau ◽  
Felipe Andreiuolo ◽  
Pascale Varlet ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Somatic Mutations ◽  
Mismatch Repair Deficiency ◽  
Mutational Signatures ◽  
Tumor Mutation Burden ◽  
Repair Deficiency ◽  
Whole Exome ◽  
Mutation Burden ◽  
Tumor Material ◽  
Constitutional Mismatch Repair Deficiency

Abstract PURPOSE Constitutional Mismatch Repair Deficiency (CMMRD) is a cancer predisposition due to bi-allelic mutations in one of the four main mismatch repair (MMR) genes (PMS2, MSH2, MSH6 or MLH1) associated with early onset of cancers, especially glioblastomas (GBM). Our aim was to decipher the molecular specificities of gliomas occurring in this context. METHODS A comprehensive analysis of clinical, histopathological and genomic data (whole exome sequencing) was performed for 12 children with a CMMRD for which we had available frozen brain tumor material (10 GBM and 2 anaplastic astrocytomas). RESULTS Eight patients harbored an ultra-mutated phenotype with more than 100 somatic non synonymous (NS) SNV/Mb. No correlation was observed between the number of mutation and sex, age, overall survival or mutated MMR gene. POLE and POLD1 exonuclease domain driver somatic mutations were described for eight and one patients respectively. The 4/12 tumors without POLE somatic mutation did not show the classical ultra-hypermutation pattern. All patients with POLE mutation had already more than 20 NS SNV/Mb (median 40NS SNV/Mb, [range 23-114]) suggesting that the hypermutation phenomenon started before the appearance of the somatic POLE mutation. The mutational signatures of the tumors, dominated by the MMR signatures, were not modified after the onset of the POLE mutation when analyzing the different mutation bursts. Specific recurrent somatic mutations were observed in SETD2 (9/12), TP53 (9/12), NF1 (9/12), EPHB2 (8/12), and DICER1 (7/12). Only half of the tumors overexpressed PDL1 by immunohistochemistry and this overexpression was not associated with a higher tumor mutation burden. CONCLUSION CMMRD-associated gliomas have a specific oncogenesis that does not trigger usual pathways and mutations seen in sporadic pediatric or adult GBM. Frequent alterations in other pathways (e.g. MAPK or DNA-PK pathway) may suggests the use of other targeted therapies aside from PD1 inhibitors.

scholarly journals Explosive mutation accumulation triggered by heterozygous human Pol ε proofreading-deficiency is driven by suppression of mismatch repair

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Karl P Hodel ◽  
Richard de Borja ◽  
Erin E Henninger ◽  
Brittany B Campbell ◽  
Nathan Ungerleider ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Dna Polymerase ◽  
Mutation Accumulation ◽  
Critical Force ◽  
Mismatch Repair Deficiency ◽  
Tumor Mutation Burden ◽  
Repair Deficiency ◽  
Mutation Burden ◽  
Generation Sequencing

Tumors defective for DNA polymerase (Pol) ε proofreading have the highest tumor mutation burden identified. A major unanswered question is whether loss of Pol ε proofreading by itself is sufficient to drive this mutagenesis, or whether additional factors are necessary. To address this, we used a combination of next generation sequencing and in vitro biochemistry on human cell lines engineered to have defects in Pol ε proofreading and mismatch repair. Absent mismatch repair, monoallelic Pol ε proofreading deficiency caused a rapid increase in a unique mutation signature, similar to that observed in tumors from patients with biallelic mismatch repair deficiency and heterozygous Pol ε mutations. Restoring mismatch repair was sufficient to suppress the explosive mutation accumulation. These results strongly suggest that concomitant suppression of mismatch repair, a hallmark of colorectal and other aggressive cancers, is a critical force for driving the explosive mutagenesis seen in tumors expressing exonuclease-deficient Pol ε.

scholarly journals B-cell acute lymphoblastic leukemia with high mutation burden presenting in a child with constitutional mismatch repair deficiency

2019 ◽  
Vol 3 (12) ◽  
pp. 1795-1798
Author(s):  
Benjamin Oshrine ◽  
Nanette Grana ◽  
Colin Moore ◽  
Johnny Nguyen ◽  
Melissa Crenshaw ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Lymphoblastic Leukemia ◽  
Treatment Strategies ◽  
Treatment Resistance ◽  
Skin Lesions ◽  
Deficiency Syndrome ◽  
Mismatch Repair Deficiency ◽  
Repair Deficiency ◽  
Mutation Burden ◽  
Constitutional Mismatch Repair Deficiency

Key Points Constitutional mismatch repair deficiency syndrome should be considered in children with acute leukemia and characteristic skin lesions. The high mutation burden of CMMRD-related cancers contributes to treatment resistance, necessitating individualized treatment strategies.

scholarly journals RARE-55. CHALLENGES AND SPECIFIC STRATEGIES FOR CONSTITUTIONAL MISMATCH REPAIR DEFICIENCY SYNDROME IN LOW RESOURCE SETTINGS. ON BEHALF OF THE INTERNATIONAL RRD CONSORTIUM IN LOW RESOURCE SETTINGS PANEL

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii454-iii454
Author(s):  
Rejin Kebudi ◽  
Nisreen Amayiri N ◽  
Malak Abedalthagafi ◽  
Asim Noor Rana ◽  
Slman Kirmani ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Checkpoint Inhibitors ◽  
Immune Therapy ◽  
Malignant Gliomas ◽  
Mismatch Repair Deficiency ◽  
Term Survival ◽  
Low Resource Settings ◽  
Low Resource ◽  
Repair Deficiency ◽  
Constitutional Mismatch Repair Deficiency

Abstract Germline biallelic mutations in one of the mismatch repair genes (MSH2/MSH6/MLH1/PMS2 results in constitutional mismatch repair deficiency (CMMRD), a condition associated with multiple tumors arising from multiple organs during childhood, and these individuals rarely reach adulthood. The paucity of information with respect to these conditions leads to mismanagement and may be a factor in the high mortality of patients with CMMRD. Two international consortia, the European CARE4CMMRD, and the international replication repair deficiency (RRD) consortium, are addressing the many challenges associated with this condition. To address specific issues surrounding the management of CMMRD in low and middle income countries (LMIC), a multidisciplinary taskforce of 11 specialists from nine countries was formed. Preliminary conclusions are: 1) Immunohistochemistry for CMMRD should be considered for all patients with suggestive clinical features. In countries where CMMRD is common, malignant gliomas, colon cancers and T cell lymphomas should be stained routinely as the prevalence of CMMRD in these tumors can exceed 40%. 2) Temozolomide should not be used in the management of malignant glioma. By contrast, preclinical studies have suggested increased sensitivity to nitrosoureas. For the management of CMMRD related lymphoma and leukemia, mercaptopurines should not be avoided or discontinued as a part of the standard of care before more data are collected. 3) Management with checkpoint inhibitors should be limited to centers with intensive care units and expertise in complex supportive care to manage side effects of immune therapy. 4) Surveillance protocols have demonstrated long term survival benefits and should be implemented in LMIC.

scholarly journals The Challenge of Diagnosing Constitutional Mismatch Repair Deficiency Syndrome in Brain Malignancies from Young Individuals

2021 ◽  
Vol 22 (9) ◽  
pp. 4629
Author(s):  
Cristina Carrato ◽  
Carolina Sanz ◽  
Ana María Muñoz-Mármol ◽  
Ignacio Blanco ◽  
Marta Pineda ◽  
...  
Keyword(s):  
Brain Tumors ◽  
Mismatch Repair ◽  
Rare Event ◽  
Deficiency Syndrome ◽  
Mismatch Repair Deficiency ◽  
Malignant Brain Tumors ◽  
Repair Deficiency ◽  
Clinical Awareness ◽  
High Degree ◽  
Constitutional Mismatch Repair Deficiency

Biallelic germline mismatch repair (MMR) gene (MLH1, MSH2, MSH6, and PMS2) mutations are an extremely rare event that causes constitutional mismatch repair deficiency (CMMRD) syndrome. CMMRD is underdiagnosed and often debuts with pediatric malignant brain tumors. A high degree of clinical awareness of the CMMRD phenotype is needed to identify new cases. Immunohistochemical (IHC) assessment of MMR protein expression and analysis of microsatellite instability (MSI) are the first tools with which to initiate the study of this syndrome in solid malignancies. MMR IHC shows a hallmark pattern with absence of staining in both neoplastic and non-neoplastic cells for the biallelic mutated gene. However, MSI often fails in brain malignancies. The aim of this report is to draw attention to the peculiar IHC profile that characterizes CMMRD syndrome and to review the difficulties in reaching an accurate diagnosis by describing the case of two siblings with biallelic MSH6 germline mutations and brain tumors. Given the difficulties involved in early diagnosis of CMMRD we propose the use of the IHC of MMR proteins in all malignant brain tumors diagnosed in individuals younger than 25 years-old to facilitate the diagnosis of CMMRD and to select those neoplasms that will benefit from immunotherapy treatment.

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