Abstract PD7-12: Molecular subtyping of male breast cancer by the International male breast cancer program (IMBC): EORTC 10085/TBCRC 0-29/BIG 2-07/NABCG/BOOG 2009-04

Introduction. Male breast cancer (male BC) is a rare disease for which disease management is extrapolated from females. IMBC, an international consortium, which previously reported on clinico-pathological aspects, now reports on molecular subgroups revealed by RNA sequencing and their relation to patient outcome.

Methods. Tumor samples from the retrospective MALE BC registry diagnosed between 1990-2010 and with pathology and outcome data (relapse-free- (RFS) and overall survival (OS)) were included (n=699). To allow the discovery of prognostic features, we selected, stratified for known risk factors (TN stage, grade, age at diagnose and adjuvant endocrine treatment), from the cohort 152 cases with poor (RFS <= 4 yrs) and good outcome (RFS > 7yrs) evenly distributed. Here, we report RNA sequencing results of the first 73 cases, 38 with poor and 35 with good outcome. RNA sequencing reads were used to generate gene expression values and to report transcripts carrying driver mutations. Unsupervised clustering identified subgroups and within subgroups differentially expressed genes were identified. The reported prognostic male BC subgroups M1 and M2 (Johansson BCR 2012(14):R31) were also annotated. All identified subgroups were related to outcome using logistic regression (p-value using Wald test).

Results. Unsupervised clustering revealed 2 main subgroups of which group 1 was enriched for expression of ER target genes, WNT3 and genes from amplicons known for female BC, e.g. 19p13 (CCNE1), 8q24 (MYC), and 11q13 (CCND1). The biology of the smaller group 2 was less defined but TGFβ2 expression was high as were various kallikreins (KLK) including interestingly KLK3 (prostate specific antigen). Other known amplified regions [(8p11 (FGFR1), 20q13 (ZNF217) and 12q15 (MDM2)] and mutated transcripts [PIK3CA (H1047R/L/Q; E542K, E545K, N345K; 16% of cases), TP53 and SF3B1 (K700E) (2% of cases)] were identified. Profound tumor infiltrate gene expression was present in 5% of cases and one third of cases expressed proliferation markers. Except for TP53, none of these latter characteristics were unevenly distributed among the 2 main subgroups. ER and AR were highly correlated, particularly in group 1. The two main groups could be further subdivided. Group 1 comprised 3 subgroups of which subgroup 1a expressed TFF1/3 and NAT1, well-known ER targets, while subgroups 1b and 1c expressed other ER targets,respectively BEX1 and PITX1. HOXC cluster expression differentiated subgroup 1b from 1a and 1c. None of these intrinsic subgroups were, however, related to RFS. The previously reported M2 subgroup, which largely segregated with subclusters 1a and 1b, was associated with a better RFS than the M1 subgroup (OR=2.9; 95%CI 1.1-7.5; p-value=0.03).

Conclusions. 1) Intrinsic subtypes of male BC were revealed and their subgrouping is defined by ER associated subsets of genes. 2) The association of the reported M2 subgroup of male BC with longer RFS was validated; 3) Currently identified biological characteristics of male BC may improve future treatments. The full report on 152 cases including a comparison to female BC will be presented at the conference.

This research was funded by Breast Cancer Research Foundation

Citation Format: Martens JWM, Sieuwerts A, Ponchet C, Smid M, de Weerd V, Slaets L, Piper T, van Deurzen CHM, Schroder CP, Stangle C, Kloosterman W, van Leeuwen-Stok E, Nilsson C, Vermeij J, Peeters S, Goulioti T, Nowaczyk M, Aebi S, Rubio IT, Kelly C, Bayani J, Porter P, Murray M, Hudis C, Middleton L, Korde L, Ruddy K, Winer E, Bogler O, van den Weyngaert D, dal Lago L, Fraser J, Benstead K, van Asperen C, Linderholm B, Hedenfalk I, Tryfonidis K, Giordano S, Bartlett J, Cardoso F. Molecular subtyping of male breast cancer by the International male breast cancer program (IMBC): EORTC 10085/TBCRC 0-29/BIG 2-07/NABCG/BOOG 2009-04 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD7-12.

Abstract P6-06-02: Functional homologous recombination REpair CAPacity (RECAP) test in metastatic breast cancer biopsies

Introduction Tumors of germline BRCA1/2 mutated carriers cannot repair DNA double strand breaks (DSB) due to homologous recombination deficiency (HRD), rendering them highly sensitive to Poly ADP Ribose Polymerase (PARP) inhibitors and DSB inducing chemotherapy. Although evidence is emerging that the use of these therapies could be extended beyond germline BRCA1/2 mutated carriers, a robust validated test to detect HRD tumors is lacking. We have developed a functional HR assay exploiting the formation of RAD51 foci in proliferating cells after ex vivo irradiation of fresh primary breast cancer (BrC) tissue: the RECAP test. Here, we investigated feasibility of this test on small biopsies from metastatic BrC lesions.

Methods Patients with advanced or recurrent BrC with easily accessible metastases were eligible. Patients with pulmonary or bone metastases were excluded due to risk of pneumothorax and technical issues with calcifications. Biopsies were collected in customized DMEM/F12 medium, irradiated with 5Gy and cultured for 2 hours. Final test outcomes were available within 1 week after the biopsy procedure. The primary endpoint was the proportion of patients with a successful test result defined as either less than 20% (i.e. HRD), 20-50% (i.e. HR intermediate), or more than 50% (i.e. HR proficient) of S/G2 phase cells showing RAD51 foci. Using a Simon 2-stage design (p0=60%, p1=80%, α=0.1, β=0.1), 38 patients were required. When at least 27 had a successful test result, we decided to further develop this test.

Results 51 patients enrolled in the RECAP trial. Core needle biopsies were collected from liver (n=16), breast (n=4), lymph nodes (n=13) and other sites (n=6), as well as punch biopsies from skin metastases (n=5). In 6 cases a biopsy could not be obtained; 1 patient was excluded as the biopsy appeared to be a metastasis of a neuroendocrine tumor. Of 44 obtained biopsies, 42 biopsies contained tumor cells. Successful test results were obtained in 40 of the 42 metastatic biopsies (95%, CI 89-100%). The reason for the two unsuccessful tests, both derived from ER+/PR+/HER2-liver metastases, was absence of tumor cells in S-phase. Success of the test in biopsies was independent of BrC subtype (p=0.12), histological grade (p=0.65), receptor status (p=0.74), biopsy type (p=0.82) and metastatic site (p=0.78). We found that 25 metastatic lesions were HR proficient, 13 were HR deficient and 2 were HR intermediate. Germline BRCA testing showed mutations in 6/13 HRD lesions. Somatic and epigenetic analyses are ongoing.

Conclusion In this study, we enhance the diagnostic potential and clinical applicability of the functional RECAP test by demonstrating novel feasibility on metastatic biopsies from BrC patients. Robustness of the test is shown, as its applicability extends from core needle biopsies from different metastatic sites to punch biopsies from skin metastases. Comparison of HRD status of primary versus metastatic tumors and among BrC subtypes will be presented at the conference.

Citation Format: Meijer TG, Verkaik NS, Naipal KAT, van Deurzen CHM, Kanaar R, van Gent DC, Jager A. Functional homologous recombination REpair CAPacity (RECAP) test in metastatic breast cancer biopsies [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-06-02.

Abstract P5-23-01: Clinical and biological characterization of male breast cancer (BC) EORTC 10085/TBCRC 029/BOOG 2013-02/BIG 2-07: Baseline results from the prospective registry

BACKGROUND: Through the International Male Breast Cancer Program, a prospective registry for male BC was created with the goals of evaluating 1) the clinical and biological features of this disease and 2) assessing feasibility of a prospective therapeutic clinical trial.

METHODS: All men, with any stage histologically proven invasive breast cancer, age 3 18 years, and newly presenting at the participating institutions (within 3 months prior) were eligible. Patients were enrolled for 30 months after activation of the first center, through February 2017. Per the study design, if <100 men enrolled, the study would be considered a failure and therapeutic trials would not be pursued through this network. Epidemiologic data, staging, pathologic features, and BRCA status were collected. Treatment and outcome data collection is ongoing. Optional collection of FFPE tumor samples, blood, and QOL were performed in the US, the Netherlands, and Latin America. Clinical database lock for this report was May 30, 2017. We currently report patient and disease characteristics and will update with patterns of treatment for the presentation. Outcomes and biological samples will be analyzed in the future.

RESULTS: 557 patients were enrolled: 75% in Europe, 20% in United States, 5% in other countries. 6.3% of patients had missing forms. Median age was 67 years (range 26-92). 93% were diagnosed 2010-2017. Among patients with complete data, 79% presented with a breast mass. 88% were M0 and 12% M1. Among M0 patients: 47%, 39%, 2%, and 11% had T1, T2, T3, and T4 disease respectively; 52% were N0. Overall, 98% had ER+ disease and 11% had HER2+ cancer. 14% had grade 1, 56% had grade 2, and 30% had grade 3 tumors. Among 112 men who underwent BRCA1 testing, 1 was positive. Among 118 men who had BRCA2 testing, 18 (15%) were positive. 21% of men had prior or concurrent malignancies, with the following most common sites: prostate, non-melanoma skin, colorectal, and melanoma. The prevalence of previously identified possible risk factors for male breast cancer were: overweight/obesity (72%), former/current smoker (51%), current alcohol 31 drink daily (41%), family history of breast cancer (35%), gynecomastia (16%), history radiation exposure (8%), use of anti-androgens (1%), and use of estrogens (1%).

CONCLUSION: Through an international collaborative effort, we were able to prospectively accrue 557 patients to a male breast cancer registry. These results demonstrate feasibility of pursuing a therapeutic clinical trial in men with breast cancer. In addition, this study shows the relatively low uptake of BRCA testing, high rates of concurrent/prior malignancy, and the rates of potentially modifiable risk factors in this patient population.

Funding from Breast Cancer Research Foundation, Susan G. Komen, Dutch Pink Ribbon Foundation, Swedish Breast Cancer Association (BRO) and EBCC Council.

Citation Format: Giordano SH, Schröder CP, Poncet C, van Leeuwen-Stok E, Linderholm B, Abreu MH, Rubio I, Van Poznak C, Morganstern D, Cameron D, Vleugel MM, Smilde TJ, Bozovic-Spasojevic I, Korde L, Russell NS, den Hoed IDM, Honkoop AH, van der Velden AWG, van 't Riet M, Dijkstra N, Bogler O, Goulioti T, Hilsenbeck S, Ruddy KJ, Wolff A, van Deurzen CHM, Martens J, Bartlett JMS, Aalders K, Tryfonidis K, Cardoso F. Clinical and biological characterization of male breast cancer (BC) EORTC 10085/TBCRC 029/BOOG 2013-02/BIG 2-07: Baseline results from the prospective registry [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-23-01.

Abstract P3-17-02: Gene expression differences between ductal carcinoma in situ with and without progression to invasive breast cancer

Background

The mechanism behind progression of ductal carcinoma in situ (DCIS) to invasive breast cancer (IBC) remains unknown. The aim of our study was to increase our understanding regarding molecular alterations driving DCIS progression by comparing gene-expression patterns between patients with pure DCIS and patients with synchronous DCIS and IBC.

Methods

In this retrospective study, we included patients with extensive pure DCIS (n=12), defined as > 5 cm, as a representation of biologically indolent lesions with limited invasive capacity. These cases were matched with patients with a limited DCIS component, defined as < 1 cm, and synchronous IBC (n=12), representing lesions with a high invasive potential. Matching was based on age and surrogate DCIS subtypes. Gene expression profiling, using 93 tumor-specific target genes, was performed to identify transcriptional differences between the DCIS components of these two groups. The identified genes were validated by immunohistochemistry.

Results

In total, for 9 genes there was a significant difference in gene expression between patients with pure DCIS and patients with DCIS and synchronous IBC. The majority of these 9 genes were significantly higher expressed in DCIS samples with IBC, including PLAU (P=0.002), COL1A1 (P=0.006), KRT81 (P=0.009), S100A7 (P=0.015), SCGB1D2 (P=0.023), KRT18 (P=0.029) and NOTCH3 (P= 0.044), while EGFR and CXCL14 showed a significantly higher expression in pure DCIS (P=0.015 and P=0.028 respectively). Based on these 9 genes, unsupervised hierarchical clustering-analysis revealed distinct clustering of patients with pure DCIS and patients with DCIS and synchronous IBC. Immunohistochemical analyses are in progress.

Conclusion

This pilot study suggests that patients with pure DCIS have a significant different gene expression pattern as compared to patients with DCIS and synchronous IBC. If these results can be validated in an independent cohort, these differently expressed genes could be used to predict progression in individual patients diagnosed with DCIS. Furthermore, these genes may pinpoint driver pathway(s) that play an important role in the progression of DCIS to IBC.

Citation Format: Doebar SC, Sieuwerts AM, de Weerd V, Martens JWM, van Deurzen CHM. Gene expression differences between ductal carcinoma in situ with and without progression to invasive breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-17-02.

Abstract P5-08-51: SIAH2 protein expression is inversely correlated with the ER status and outcome to tamoxifen therapy in metastatic breast cancer patients

Introduction: In a previous study we observed a positive correlation between Seven in Absentia Homolog 2 (SIAH2) and Estrogen Receptor (ER) mRNA levels. Additionally, high SIAH2 mRNA levels were related to a favorable progression-free survival (PFS) after first-line tamoxifen. In contrast, others showed high SIAH2 protein levels in ER-negative breast cancer associated with an unfavorable relapse-free survival. In this study, we investigated the above discrepancy between SIAH2 protein and mRNA findings and evaluated the prognostic and predictive value of SIAH2 protein in breast cancer patients.

Patients and methods: Tissue microarrays (TMAs) of formalin-fixed, paraffin-embedded primary breast tumors were immunohistochemically stained for SIAH2 protein. The TMAs contained core specimens of 759 patients with early disease and of 245 ER-positive patients with advanced disease treated with first-line tamoxifen. SIAH2 protein staining was scored for its intensity and proportion positive cells and subsequently evaluated for its relationship with metastasis-free survival (MFS) and PFS in uni- and multivariate analyses including traditional prognostic or predictive factors, respectively.

Results: The proportion SIAH2-positive cells had a relationship with MFS and PFS, whereas staining intensity and a previous described score for SIAH2 combining intensity and proportion were not related with clinical outcome. Based on these results, tumors with more than 20% positive cells were considered as SIAH2-positive. In early disease, 267 patients (35%) had SIAH2-positive tumors, which were further characterized by decreased expression of ER at protein and mRNA levels (P <0.001 and P = 0.003, respectively). These SIAH2-positive tumors correlated with significant unfavorable MFS in lymph node negative, ER-positive breast cancer patients, but only in univariate analysis. In advanced disease, 86 patients (35%) had SIAH2-positive tumors which was associated with an unfavorable PFS after first-line tamoxifen in both uni- and multivariate analyses (HR = 1.45; 95% CI, 1.07 to 1.96; P = 0.015).

Conclusions: SIAH2 protein expression is especially observed in ER-negative tumors and has no additional prognostic value in breast cancer. The proportion SIAH2-positive cells in ER-positive tumors can be used as biomarker to predict tamoxifen treatment failure in breast cancer patients with advanced disease. Future studies should establish if expression of certain microRNAs explain the observed discrepancy in SIAH2 mRNA and protein levels.

Citation Format: van der Willik KD, Timmermans MM, Look MP, Reijm EA, van Deurzen CHM, den Bakker MA, Westenend PJ, Martens JWM, Berns EMJJ, Jansen MPHM. SIAH2 protein expression is inversely correlated with the ER status and outcome to tamoxifen therapy in metastatic breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-51.

Abstract P5-05-05: Lower mitotic activity in BRCA1/2-associated primary breast cancers occurring after risk-reducing salpingo-oophorectomy

Background Bilateral salpingo-oophorectomy reduces breast cancer (BC) risk by about 50% in BRCA1/2 mutation carriers when performed premenopausally. It has been hypothesized that growth activity of BCs originating after risk-reducing salpingo-oophorectomy (RRSO) is lower. We compared tumor characteristics and growth rates of BRCA1/2-associated primary BCs (PBCs) detected after RRSO with those of tumors originating without RRSO.

Methods From a cohort of 271 female BRCA1/2-associated patients with screen detected BC, 20 BRCA1/2 mutation carriers with PBC detected ≥12 months after RRSO were selected (RRSO group). Controls were 36 BRCA1/2 mutation carriers with PBC detected without RRSO (non-RRSO group) matched for age at PBC diagnosis (± 2.5 years) and for BRCA1 or BRCA2 mutation (intended matching ratio 1:2). Tumor growth rates, expressed as tumor volume doubling times (DT), were calculated. Pathology samples were revised for histological subtype, tumor differentiation grade, estrogen receptor (ER), progesterone receptor (PR) and HER2 status. Imaging examinations (magnetic resonance imaging (MRI), mammography) before and at BC diagnosis were revised.

Results Median age at PBC diagnosis was 52 years (range 35-67). MRI detected more BC than mammography in the RRSO-group as compared to the non-RRSO group (83% vs. 39%, P = 0.02). Tumor size at diagnosis was smaller in the RRSO group (11.0 mm vs. 17.0 mm, P = 0.01). Mitotic activity indexes (MAI) in the RRSO and non-RRSO group were 12 vs. 22 mitotic counts/2 mm2 (P = 0.02). No significant differences in differentiation grade, ER and HER2 status were found. PR-status was more often positive in the RRSO group without reaching statistical significance (38% vs. 13%, P = 0.07). Median DT in the RRSO group was 124 days (range 89-193) and 93 days (range 54-253) in the non-RRSO group (P = 0.47).

Conclusion BC occurring after RRSO in BRCA mutation carriers features a lower MAI, suggesting a less aggressive biological behavior. When confirmed in larger series, this may have consequences for BC screening protocols for BRCA1/2 mutation carriers after RRSO.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-05-05.

Abstract P5-01-13: Flat Epithelial Atypia: Management and outcome in three Dutch teaching hospitals

Background: Flat Epithelial Atypia (FEA) is a presumably neoplastic alteration of terminal duct-lobular units, characterized by the replacement of native luminal epithelium by ductal cells demonstrating low-grade cytologic atypia. The architecture shows stratification of epithelial cells. FEA is often accompanied by microcalcifications and therefore discovered in biopsies following screening mammography. FEA is frequently seen in association with ADH (atypical ductal hyperplasia), DCIS (ductal carcinoma in situ), lobular neoplasia and invasive tubular carcinomas. There is emerging evidence suggesting FEA may represent a precursor to DCIS. The risk of subsequent breast carcinoma remains to be defined. The aim of this study is therefore to inventorise the management and outcome of solitary FEA in histological biopsies in three Dutch teaching hospitals.

Materials and Methods: Data of this retrospective multicentre study were collected in a database. Local pathology databases were screened with the terms: ‘FEA’, ‘Flat Epithelial Atypia’, ‘columnar atypia’ and Dutch equivalents. Results were manually screened, only including solitary FEA.

Patient files were viewed for information on presentation, mammography, ultrasound and management: surgery vs follow-up. In case of excision, definitive pathology was added.

Results: We included 103 patients showing only solitary FEA in the primary biopsy. Management of these patients consisted of follow-up for 60 patients (58,3%) and surgery for 43 patients (41,7%, 49 excisions): lumpectomy (42) or mastectomy (7). Reason for choosing mastectomy was preventive in case of contralateral breast cancer or increased familial or genetic risk.

Definitive pathology of lumpectomy or mastectomy showed no abnormalities or solitary FEA in 31 patients; other findings were ADH in 7, LCIS in 4 and DCIS in 7 patients. Some patients showed more than one finding. Invasive breast cancer (IBC) was detected in 3 patients. Only one mastectomy showed invasive disease, located in a different lobe, however.

No incidents occurred in the follow-up group.

Conclusions: No consistent management exists concerning solitary FEA in these three hospitals. Also, one hospital used the diagnosis of FEA inconsistently and interchangingly with other terms. Lack of this study is the retrospective gathering of data, making it difficult to detect the reasons for the chosen management. DCIS or IBC was discovered in 20,4% of all surgical specimens. It was concluded that FEA should be seen as a red flag, indicating the possible presence of a more malignant lesion. Additional research is warranted concerning long term follow-up for this patient group.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-01-13.