Abstract P6-09-03: Association of Caspase 8 polymorphisms with TILs and disease-free survival in primary breast cancer patients

BACKGROUND: The minor allele of two caspase-8 polymorphisms, namely CASP8 -652 6N InsDel and CASP8 Asp302His, were shown to promote survival of T-lymphocytes and were repeatedly associated with reduced breast cancer susceptibility. However, besides some preliminary findings, clinical relevance of these polymorphisms in patients with already existing primary breast cancer has not yet been established. Considering an immunomodulatory and potentially tumor-protective role of these caspase-8 variants, we genotyped 785 primary breast cancer patients and correlated caspase-8 variants with i) disease-free survival (DFS) and ii) the presence of tumor infiltrating lymphocytes (TILs).

METHODS: Primary breast cancer samples were collected at the Martin-Luther University, Halle-Wittenberg between 2009 and 2011 as part of the multicenter prospective PiA trial (NCT 01592825). The majority of patients had luminal-like tumors (75.9%), followed by triple negative (10.1%), luminal-Her2-like (9.6%) and Her2-enriched tumors (4.5%). Genotyping was performed by pyrosequencing, TILs status was assessed by hematoxylin and eosin staining.

RESULTS: The CASP8 -652 deletion was significantly associated with improved DFS in an allele-dose dependent manner (p=0.027). Homozygosity for the -652 6N Del variant was an independent predictor for improved DFS (p=0.005). In patients with a 302His/His genotype, there was no event of recurrence during the entire observation time. Combined analysis of diplotypes revealed that both polymorphisms had an influence on DFS (p=0.029). Interestingly, patients with the 302His/His variant among the unstratified patient cohort and among the luminal-like subtype alone had tumors with very low lymphocyte infiltration (0-10% TILs in 65% of cases compared to 31% of cases for other genotypes, p=0.025).

CONCLUSION: In line with previous epidemiological findings, we propose a prognostically favorable role of the CASP8 -652 6N Del and the Asp302His variant in primary breast cancer patients. Moreover, we suggest for the first time a role of the Asp302His variant in immunosurveillance and lymphocyte infiltration of breast cancer. Our findings strongly encourage further analyze of these genetic variants as a biomarker for prognostic and immunotherapeutic considerations.

Citation Format: Wimberger P, Bachmann HS, Kuhlmann JD, Link T, Kröber E, Thomssen C, Malle B, Vetter M, Kantelhardt EJ. Association of Caspase 8 polymorphisms with TILs and disease-free survival in primary breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-09-03.

Prognostic relevance of caspase 8 -652 6N InsDel and Asp302His polymorphisms for breast cancer

Background

The minor allele of two caspase 8 polymorphisms, namely CASP8 -652 6N InsDel (rs3834129) and CASP8 Asp302His (rs1045485), were repeatedly associated with reduced breast cancer susceptibility. Contrarily, the presence of the -652 6N Del or the CASP8 302His variant was reported to be an unfavorable prognostic factor in colorectal cancer or neuroblastoma. However, prognostic relevance of these genetic variants for breast cancer is completely unknown and is therefore adressed by the current study.

Methods

Genotyping was performed by pyrosequencing. Caspase 8 mRNA expression was quantified by comparative RT-qPCR.

Results

We observed an allele-dose dependent association between CASP8 -652 6N InsDel and caspase 8 mRNA expression in breast cancer tissue, with homozygous deletion carriers showing lowest relative caspase 8 expression (p = 0.0131). Intriguingly, the presence of the -652 6N Del or the 302His variant was shown to be a negative prognostic factor for breast cancer in terms of an allele-dose dependent influence on overall survival (OS, p = 0.0018, p = 0.0150, respectively). Moreover, both polymorphisms were independent predictors of OS after adjusting for co-variats (p = 0.007, p = 0.037, respectively). Prognostic relevance of both polymorphisms were confirmed to be independent from each other and combined analysis of diplotypes revealed an additive influence upon OS (p = 0.0002).

Conclusion

This is the first report, showing negative and independent prognostic impact of the CASP8 -652 6N Del and the 302His variant for breast cancer. Our data provide rationale to further validate clinical utility of these polymorphisms for breast cancer and to extend this investigation to a broad scope of other malignancies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2662-x) contains supplementary material, which is available to authorized users.

Abstract LB-044: Germline mutations in patients with hereditary breast and ovarian cancer establish ERCC2 as a cancer susceptibility gene

Introduction: Breast and ovarian cancer (BC/OC) predisposition is associated with a number of high- and low-penetrance susceptibility genes. Despite comprehensive testing there is still a large portion of high risk cases without mutation in any of the known susceptibility loci. Therefore novel candidate genes need to be identified. Here we report on the results of testing 94 genes in 717 BC/OC patients from Germany and Lithuania.

Method: Inclusion criteria for the patients in this study were defined by the German Consortium for Breast and Ovarian Cancer. Next generation sequencing (NGS) was performed on an Illumina MiSeq sequencer, with 150 bp paired end sequencing chemistry and an average base coverage of 300 fold. Target enrichment was performed with the Illumina TruSight cancer panel, which includes 94 genes associated with both common (e.g., breast, colorectal) and rare cancers.

Results: In 19.7% of the patients, BRCA1 or BRCA2 variations have been found. These were either clearly pathogenic loss-of-function mutations (43%) or very rare, unclassified missense variations with high probability of a deleterious effect (57%). In 17.9% of the patients we found null-mutations and rare, unclassified missense variants in the acknowledged BC/OC susceptibility genes ATM, CDH1, CHEK2, NBN, PALB2, RAD51C/D and TP53. Analysis of the non-BC/OC genes on the NGS panel identified the “excision repair cross-complementing rodent repair deficiency, complementation group 2” gene (ERCC2 or XPD) as a promising BC/OC predisposition candidate: we found 3 frame-shift mutations and 1 splice-site mutation in four independent BC/OC families. Additionally we found 20 rare, unclassified sequence variations in ERCC2. These variants have a cumulative allele frequency of 2.9% in our BC/OC cohort, which is 14.5-fold overrepresentation compared to the “exome aggregation consortium” (ExAC) cohort (61486 exomes). In all affected families tested so far, the ERCC2 mutations co-segregate with the occurrence of BC and/or OC. Functional assays testing the ERCC2 variants have been initiated. First results show that at least some of the missense variants (e.g. NM_000400.3:p.Val536Met) have lost their DNA repair ability.

Conclusion: Deleterious mutations and probably pathogenic missense variations in ERCC2, which are significantly overrepresented in our BC/OC families and co-segregate with the affected individuals, define ERCC2 clearly as a susceptibility gene for BC/OC predisposition. Functional assays will be continued in order to identify missense variations that diminish the DNA-repair capacity of ERCC2. Affected individuals with excluded mutations in the known BC/OC predisposition genes should be tested for mutations in ERCC2.

Citation Format: Evelin Schrock, Anna Benet-Pagès, Steffen Schubert, Ramūnas Janavicius, Karl Hackmann, Elitza Betcheva-Krajcir, Luisa Mackenroth, Janin Lehmann, AM Nissen, Janine Altmueller, Holger Thiele, Nataliya Di Donato, Barbara Klink, Jan D. Kuhlmann, Andreas Tzschach, Karin Kast, Pauline Wimberger, Elke Holinski-Feder, Alfons Meindl, Steffen Emmert, Andreas Rump. Germline mutations in patients with hereditary breast and ovarian cancer establish ERCC2 as a cancer susceptibility gene. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-044. doi:10.1158/1538-7445.AM2015-LB-044

Abstract 2217: Primary tumor loss of heterozygosity proximal to M6P/IGF2R locus is predictive for the presence and persistence of disseminated tumor cells in the bone marrow of ovarian cancer patients

Introduction: Disseminated tumor cells (DTC) in the bone marrow (BM) are present in about 35% of all ovarian cancer patients before surgery and after platinum-based chemotherapy which has been associated with an adverse prognosis. Since invasive BM aspirations are less accepted and often not feasible, it would be highly desirable to unmask a molecular biomarker in the primary tumor predicting tumor cell spread and persistence. It was the purpose of the study to 1) investigate loss of heterozygosity (LOH) incidence at four ovarian cancer relevant chromosomal loci involved in inter alia apoptosis, platinum sensitivity or DNA repair in primary ovarian tumor tissue 2) assess the prognostic value of LOH after a median follow-up time of three years and 3) correlate LOH incidence with the occurrence of DTC before surgery and after platinum-based chemotherapy.

Methods: In total, 88 ovarian cancer patients were recruited for this study. Primary tumor DNA was extracted from paraffin embedded tissue and analyzed for LOH status at four polymorphic microsatellite markers including D10S1765 (PTEN locus), D13S218 (BRCA1 locus), D17S855 (BRCA2 locus) and D6S1581 (proximal to M6P/IGF2R locus) using PCR-based fluorescence microsatellite analysis. BM aspirates were feasible in 53 patients before surgery and in 40 patients after chemotherapy. BM cells were isolated from heparinized BM by Ficoll-Hypaque density gradient centrifugation and analyzed for DTC by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3.

Results: In our cohort of 88 patients, we recorded at least one LOH in 56/88 patients (63%), two LOH in 30/88 patients (34%), three LOH in 8/88 patients (9%) and LOH at all four markers in 3/88 patients (3%), respectively. The occurrence of LOH at the entire marker set significantly correlated with tumor grading (p=0.0001) and histology (p=0.004). The frequency of LOH at the marker D10S1765 correlated with FIGO stage (p=0.046) and grading (p=0.05) whereas LOH at D17S855 was associated with grading (p=0.023) and histology (p=0.012). The occurrence did not correlate with disease free as well as overall survival. Prior to surgery, DTC were detected in 26/53 patients (49%) with a median number of 6 cells (range 1-38 cells). After chemotherapy, 20/40 patients (50 %) revealed DTC in their BM with a median number of 10 cells, ranging from 1 to 35 cells. Interestingly, the LOH incidence proximal to D6S1581 significantly correlated with DTC presence before surgery (p=0.05) as well as DTC persistence after chemotherapy (p=0.022).

Conclusion: In primary ovarian tumors, allelic loss proximal to D6S1581 might serve as a potential molecular biomarker for the presence and persistence of DTC in the BM. Further investigations have to prove whether such a molecular marker could replace invasive BM aspirations in the future.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2217. doi:10.1158/1538-7445.AM2011-2217