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PanCurX_hrd - samples

ABSTRACT: Background and Aims: Homologous recombination deficiency (HRD) in pancreatic ductal adenocarcinoma (PDAC), remains poorly defined beyond germline(g) alterations in BRCA1, BRCA2 and PALB2. Methods: We interrogated whole genome sequencing (WGS) data on 391 patients including 49 carriers of pathogenic variants (PVs) in g_BRCA_ and PALB2. HRD classifiers were applied to the dataset and included: 1) the genomic instability score (GIS) used by Myriad MyChoice HRD assay; 2) substitution base signature 3 (SBS3); 3) HRDetect; and, 4) Structural Variant (SV) burden. Clinical outcomes and responses to chemotherapy were correlated with HRD status. Results: Biallelic tumour inactivation of g_BRCA_ or PALB2 was evident in 43/49 germline carriers identifying HRD-PDAC. HRDetect (score ?0.7) predicted gBRCA1/PALB2 deficiency with highest sensitivity (98%) and specificity (100%). HRD genomic tumour classifiers suggested that 7-10% of PDAC that do not harbor g_BRCA/PALB2_ have features of HRD. Of the somatic HRDetect cases, 69% were attributed to alterations in BRCA1/2, PALB2, RAD51C/D and XRCC2, and a tandem duplicator phenotype. TP53 loss was more common in BRCA1- compared to BRCA2-associated HRD-PDAC. HRD status was not prognostic in resected PDAC. However in advanced disease the GIS (p=0.02), SBS3 (p=0.03) and HRDetect score (p=0.005) were predictive of platinum response and superior survival. PVs in g_ATM_ (n=6) or g_CHEK2_ (n=2) did not result in HRD-PDAC by any of the classifiers. In four patients, BRCA2 reversion mutations associated with platinum resistance. Conclusions: Germline and parallel somatic profiling of PDAC outperforms germline testing alone in identifying HRD-PDAC. An additional 7-10% of patients without gBRCA/PALB2 mutations may benefit from DNA damage response agents.

PROVIDER: EGAD00001007571 | EGA |

REPOSITORIES: EGA

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Project description:Background:This study was a hypothesis generating exploration of genomic data collected at diagnosis for 19 patients, who later participated in a clinical trial. BRCA1/2 germline mutation related hereditary cancers are candidates for new immune therapeutic interventions. However, contrary to what is expected of tumors with compromised DNA repair, a prominent tumor mutation burden (TMB) in hereditary breast and ovarian cancers in this cohort, was not correlated with high global immune activity in their microenvironments. More information is needed about the relationship between genomic instability, phenotypes and immune microenvironments of BRCA1/2 related hereditary tumors in order to find appropriate markers of immune activity and the most effective anticancer immune strategies. Methods:Mining and statistical analyses of the original DNA and RNA sequencing data and data available from The Cancer Genome Atlas (TCGA) were performed using the R computing environment. To interpret the data, we have used published literature and web available resources such as Gene Ontology Tools, The Cancer immunome Atlas (TCIA) and the Cancer Research Institute iAtlas. Results: We found that BRCA1/2 germline related breast and ovarian cancers do not represent a unique phenotypic identity, but that they express a range of phenotypes similar to sporadic cancers. Importantly, BRCA2 germline mutation related breast tumors have a different profile of genomic instability compared to those related to BRCA1. However, all breast and ovarian BRCA1/2 related tumors are characterized by high homologous recombination deficiency (HRD) and low aneuploidy. Interestingly, all sporadic high grade serous ovarian cancers (HGSOC) and most of the subtypes of triple negative breast cancers (TNBC), but not other types of breast cancer, also express a high degree of HRD. Conclusion: : Tumor mutation burdon (TMB) is not associated with the magnitude of the immune response in hereditary BRCA1/2 related breast and ovarian cancers or in sporadic TNBC and sporadic HGSOC. Hereditary tumors express phenotypes as heterogenous as sporadic tumors with various degree of “BRCAness” and various characteristics of the immune microenvironments. The subtyping criteria developed for sporadic tumors can be applied for the classification of hereditary tumors and possibly also characterization of their immune microenvironment. A high HRD score may be a good candidate biomarker for response to platinum, and potentially PARP-inhibition.

Project description:Molecular Profiling of BRCA1-and BRCA2-associated Breast Cancers Identifies FGFR2 as a Gene More Highly Expressed in BRCA2-associated Tumors BRCA1- and BRCA2-associated tumors have many morphologic characteristics in common, but appear to have distinct molecular signatures. BRCA1-associated tumors are predominantly basal-like cancers, whereas BRCA2-associated tumors have a predominant luminal-like phenotype. These two molecular signatures reflect in part the two cell types, basal/myoepithelial and luminal, found in the terminal duct lobular unit of the breast. To elucidate novel genes involved in these two spectra of breast cancer tumorigenesis we performed global gene expression analysis on breast tumors from germline BRCA1 and BRCA2 mutation carriers. Breast tumor RNAs from 7 germline BRCA1 and 6 germline BRCA2 carriers were profiled using UHN human 19K cDNA microarrays. Supervised univariate analyses were conducted to identify genes differentially expressed between BRCA1 and BRCA2-associated tumors. Selected discriminatory genes were validated using real time reverse transcription polymerase chain reaction (RT-PCR) in the tumor RNAs, and/or by immunohistochemistry (IHC) or by in situ hybridization (ISH) on tissue microarrays (TMAs) containing an independent set of 58 BRCA1 and 64 BRCA2-associated tumors. Genes more highly expressed in BRCA1-associated tumors included stathmin/oncoprotein 18, osteopontin, TGFß2 and Jagged 1 in addition to genes previously identified as characteristic of basal-like breast cancers. Genes more highly expressed in BRCA2-associated tumors had functions related to transcription, signal transduction (particularly MAPK signaling), cell proliferation, cell adhesion and extracellular matrix remodeling. BRCA2-associated cancers were characterized by the higher relative expression of amongst others, FGF1 and FGFR2. Tissue microarrays were used to validate the expression of FGFR2 protein by immunohistochemistry and Jagged 1 expression by in situ hybridization. BRCA2-associated cancers expressed higher levels of FGFR2 protein than BRCA1-associated cancers (p=0.004); whereas BRCA1-associated tumors exhibited elevated levels of Jagged1 mRNA compared to BRCA2-associated cancers (p=0.02). FGFR2 and FGF1 were more highly expressed in BRCA2-associated cancers compared with BRCA1-associated breast cancers, suggesting the existence of an autocrine or paracrine stimulatory loop. In addition to corroborating the basal-like signature of BRCA1-associated tumors, we identified osteopontin, stathmin/oncoprotein 18, TGFβ2, and Jagged 1 as being more highly expressed in BRCA1-associated tumors. Keywords: Gene expression profiling, genetic comparison

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PanCurX_hrd - samples

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