Interobserver Variation in the Assessment of Immunohistochemistry Expression Levels in HER2-Negative Breast Cancer: Can We Improve the Identification of Low Levels of HER2 Expression by Adjusting the Criteria? An International Interobserver Study

The classification of human epidermal growth factor receptor 2 (HER2) expression is optimized to detect HER2-amplified breast cancer (BC). However, novel HER2-targeting agents are also effective for BCs with low levels of HER2. This raises the question whether the current guidelines for HER2 testing are sufficiently reproducible to identify HER2-low BC. The aim of this multicenter international study was to assess the interobserver agreement of specific HER2 immunohistochemistry scores in cases with negative HER2 results (0, 1+, or 2+/in situ hybridization negative) according to the current American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines. Furthermore, we evaluated whether the agreement improved by redefining immunohistochemistry (IHC) scoring criteria or by adding fluorescent in situ hybridization (FISH). We conducted a 2-round study of 105 nonamplified BCs. During the first assessment, 16 pathologists used the latest version of the ASCO/CAP guidelines. After a consensus meeting, the same pathologists scored the same digital slides using modified IHC scoring criteria based on the 2007 ASCO/CAP guidelines, and an extra "ultralow" category was added. Overall, the interobserver agreement was limited (4.7% of cases with 100% agreement) in the first round, but this was improved by clustering IHC categories. In the second round, the highest reproducibility was observed when comparing IHC 0 with the ultralow/1+/2+ grouped cluster (74.3% of cases with 100% agreement). The FISH results were not statistically different between HER2-0 and HER2-low cases, regardless of the IHC criteria used. In conclusion, our study suggests that the modified 2007 ASCO/CAP criteria were more reproducible in distinguishing HER2-0 from HER2-low cases than the 2018 ASCO/CAP criteria. However, the reproducibility was still moderate, which was not improved by adding FISH. This could lead to a suboptimal selection of patients eligible for novel HER2-targeting agents. If the threshold between HER2 IHC 0 and 1+ is to be clinically actionable, there is a need for clearer, more reproducible IHC definitions, training, and/or development of more accurate methods to detect this subtle difference in protein expression levels.

Abstract P2-08-23: Early intratumoral changes after a single dose of anti-PD-1 treatment in patients with early breast cancer (BC)

Intro: Despite the growing success of immune checkpoint blockade in BC, the underlying mechanisms of response or resistance to these treatments is still poorly understood. We recently conducted a window-of-opportunity study (BioKey) including 54 patients with early BC (NCT03197389) in which patients were treated with one dose of pembrolizumab 10 ± 4 days before surgery. A tumor biopsy was taken before and after the administration of pembrolizumab. Using single-cell transcriptome profiling, we identified patients with clonotype expansion of PD-1-expressing T-cells after treatment with pembrolizumab (Bassez A, Vos H et al, Nature Medicine 2021). Expansion mainly involved CD8+ T - and CD4+ T cells. We designated these as patients with clonotype expansion or ‘expanders’ (E), whereas patients lacking clonotype expansion were considered ‘non-expanders’ (NE). In this study, we aimed at investigating the association between stromal tumor infiltrating lymphocytes (sTIL) and various immune markers using immunohistochemistry with the E phenotype. Methods: The BioKey trial has 2 cohorts. The first one included 39 treatment-naive patients who were scheduled for upfront surgery. The second cohort included 15 patients with an estimated residual tumor size of at least 1cm on imaging after neo-adjuvant chemotherapy. All molecular subtypes were represented: triple-negative (TN) BC (n= 18, 8 E and 10 NE), HER2-positive BC (n= 5, 1 E and 4 NE) and hormone receptor (HR)-positive/HER2-negative BC (n= 17, 3 E and 14 NE). 7 core biopsies and 5 resection slides were not contributive and were excluded. The expander status of 14 patients was unknown. sTIL were evaluated and immunohistochemical stains (CD3, CD4, CD8, CD68, CD73, FoxP3, Ki67, PD-1 and PD-L1) were performed. Associations between expander status and biomarkers were assessed using firth logistic regressions, adjusting per cohort. Biomarkers were considered as continuous variables and Odds Ratio computed per one unit increase on a non-transformed scale. Given the low number of E in cohort B, subgroup analyses were performed only in cohort A. Results: We observed that 1) higher levels of sTIL, PD-1+ sTIL and FOXP3+ cells in the pre-treatment biopsies, 2) higher levels of sTIL, PD1+ sTIL, PD-L1+, CD3+, CD4+, CD8+, CD68+, FOXP3+ cells and Ki67 in the post-treatment surgical specimen, as well as, 3) higher delta values (surgical specimen - biopsy) of sTIL, CD3+, CD4+, CD8+, CD68+ and Ki67 are associated with the E phenotype (Table 1). With regard to the subgroup analyses, we observed that higher levels of PD-1+ sTIL and CD68+ cells at diagnosis and surgery respectively, as well as higher delta values for CD68+, Ki67 and sTIL were associated with the E phenotype in HR+/HER2- BC, while high levels of FOXP3+ cells and PD-1+ sTILs in the biopsies, high levels of sTIL, CD3+, CD4+, CD8+, CD68+, FOXP3+, PD-1+ sTILs, PD-L1+ and Ki67 as well as higher delta values for PD-L1+ in the resection specimen were associated with the E phenotype in TNBC. Conclusion: We were able to detect associations between various cell populations of the tumor immune microenvironment evaluated before and after a single dose of pembrolizumab and the T-cell expansion phenotype previously defined at the single-cell level. It highlights the possible clinical utility of a biopsy taken early during treatment. Future neo-adjuvant studies will allow the validation of our findings and investigate the association between T-cell expansion and clinical outcomes.

Table 1.Association between the various biomarkers and the expanding T-cell phenotypeVariableOdds RatioLower 95% CIUpper 95% CIp-valuePre-treatment. Core biopsyCD31.071.001.160.061CD41.060.981.170.156CD81.130.951.380.161CD681.050.901.230.494CD73.tumor1.070.821.370.609CD73.on sTIL1.010.961.060.713FoxP32.251.394.030.001Ki671.021.001.050.107sTIL1.061.021.140.005PD-1 on sTIL1.731.212.830.001PD-L11.041.011.070.002Post-treatment. Resection specimenCD31.091.031.190.001CD41.151.051.29<0.001CD81.581.192.34<0.001CD681.471.152.15<0.001CD73.tumor1.090.771.520.608CD73.on sTIL1.030.991.080.110FoxP32.051.313.82<0.001Ki671.041.011.070.004sTIL1.081.031.15<0.001PD-1 on sTIL1.641.152.650.004PD-L11.051.021.110.002Delta (resection-biopsy)CD31.071.011.250.029CD41.091.011.280.030CD81.211.021.690.025CD681.221.051.580.007CD73.tumor0.970.731.290.794CD73.on sTIL1.040.991.120.132FoxP31.220.891.810.219Ki671.051.001.130.031sTIL1.071.001.160.046PD-1 on sTIL0.960.701.330.765PD-L11.000.961.040.941

Citation Format: Hanne Vos, Kathleen Lambein, François Richard, Ines Nevelsteen, Ayse Bassez, Diether Lambrechts, Kevin Punie, Hans Wildiers, Giuseppe Floris, Christine Desmedt, Ann Smeets. Early intratumoral changes after a single dose of anti-PD-1 treatment in patients with early breast cancer (BC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-08-23.

Interobserver variability in the assessment of stromal tumor-infiltrating lymphocytes (sTILs) in triple-negative invasive breast carcinoma influences the association with pathological complete response: the IVITA study

High stromal tumor-infiltrating lymphocytes (sTILs) in triple-negative breast cancer (TNBC) are associated with pathological complete response (pCR) after neoadjuvant chemotherapy (NAC). Histopathological assessment of sTILs in TNBC biopsies is characterized by substantial interobserver variability, but it is unknown whether this affects its association with pCR. Here, we aimed to investigate the degree of interobserver variability in an international study, and its impact on the relationship between sTILs and pCR. Forty pathologists assessed sTILs as a percentage in digitalized biopsy slides, originating from 41 TNBC patients who were treated with NAC followed by surgery. Pathological response was quantified by the MD Anderson Residual Cancer Burden (RCB) score. Intraclass correlation coefficients (ICCs) were calculated per pathologist duo and Bland-Altman plots were constructed. The relation between sTILs and pCR or RCB class was investigated. The ICCs ranged from -0.376 to 0.947 (mean: 0.659), indicating substantial interobserver variability. Nevertheless, high sTILs scores were significantly associated with pCR for 36 participants (90%), and with RCB class for eight participants (20%). Post hoc sTILs cutoffs at 20% and 40% resulted in variable associations with pCR. The sTILs in TNBC with RCB-II and RCB-III were intermediate to those of RCB-0 and RCB-I, with lowest sTILs observed in RCB-I. However, the limited number of RCB-I cases precludes any definite conclusions due to lack of power, and this observation therefore requires further investigation. In conclusion, sTILs are a robust marker for pCR at the group level. However, if sTILs are to be used to guide the NAC scheme for individual patients, the observed interobserver variability might substantially affect the chance of obtaining a pCR. Future studies should determine the 'ideal' sTILs threshold, and attempt to fine-tune the patient selection for sTILs-based de-escalation of NAC regimens. At present, there is insufficient evidence for robust and reproducible sTILs-guided therapeutic decisions.

Stromal Changes are Associated with High P4HA2 Expression in Ductal Carcinoma in Situ of the Breast

Ductal carcinoma in situ (DCIS) of the breast is able to induce stromal changes, which likely reflect the crosstalk between DCIS and its microenvironment. These changes harbor prognostic information, although the interobserver variability of scoring stromal changes is moderate. A more robust evaluation of the DCIS-associated stroma is therefore needed. The aim of this study was to characterize P4HA2 expression, which is involved in collagen biosynthesis, in DCIS and to assess whether P4HA2 expression enables a more robust evaluation of the DCIS-associated stroma compared to histomorphology. This study included 410 patients with DCIS. Stromal changes were scored on hematoxylin/eosin-stained whole slides. P4HA2 expression in DCIS-associated stroma was assessed by whole slide immunohistochemistry. One hundred DCIS lesions were evaluated by seven pathologists to study the interobserver variability in the assessment of stromal changes and stromal P4HA2 expression. High P4HA2 expression in stromal fibroblasts was present in 14.1% of the patients. High P4HA2 expression was associated with the presence of periductal stromal changes (P = 0.004). The interobserver variability was similar for the assessment of stromal changes and the percentage of P4HA2-positive fibroblasts. Although we demonstrated a significant association between high P4HA2 expression in fibroblasts and the morphological presence of stromal changes, it seems unlikely that P4HA2 expression can be used as an alternative for the histopathological evaluation of the DCIS-associated stroma.

A single-cell map of intratumoral changes during anti-PD1 treatment of patients with breast cancer

Immune-checkpoint blockade (ICB) combined with neoadjuvant chemotherapy improves pathological complete response in breast cancer. To understand why only a subset of tumors respond to ICB, patients with hormone receptor-positive or triple-negative breast cancer were treated with anti-PD1 before surgery. Paired pre- versus on-treatment biopsies from treatment-naive patients receiving anti-PD1 (n = 29) or patients receiving neoadjuvant chemotherapy before anti-PD1 (n = 11) were subjected to single-cell transcriptome, T cell receptor and proteome profiling. One-third of tumors contained PD1-expressing T cells, which clonally expanded upon anti-PD1 treatment, irrespective of tumor subtype. Expansion mainly involved CD8⁺ T cells with pronounced expression of cytotoxic-activity (PRF1, GZMB), immune-cell homing (CXCL13) and exhaustion markers (HAVCR2, LAG3), and CD4⁺ T cells characterized by expression of T-helper-1 (IFNG) and follicular-helper (BCL6, CXCR5) markers. In pre-treatment biopsies, the relative frequency of immunoregulatory dendritic cells (PD-L1⁺), specific macrophage phenotypes (CCR2⁺ or MMP9⁺) and cancer cells exhibiting major histocompatibility complex class I/II expression correlated positively with T cell expansion. Conversely, undifferentiated pre-effector/memory T cells (TCF7⁺, GZMK⁺) or inhibitory macrophages (CX3CR1⁺, C3⁺) were inversely correlated with T cell expansion. Collectively, our data identify various immunophenotypes and associated gene sets that are positively or negatively correlated with T cell expansion following anti-PD1 treatment. We shed light on the heterogeneity in treatment response to anti-PD1 in breast cancer.

Abstract P5-04-23: Characterization of the tumor microenvironment in a large series of ER/PR negative breast cancer

Introduction: Recent data show that a subgroup of patients with breast cancer might benefit from immune checkpoint blockade (ICB). However, adequate biomarkers to select patients for ICB are lacking. A better understanding of the immune microenvironment of breast cancer is paramount in the quest for appropriate biomarkers. We investigated several immune related parameters in hormone receptor negative breast cancer, attempting to characterize the tumor microenvironment. We observed the immune micro-environment from three angles. Firstly, we counted and further characterised stromal tumour infiltrating lymphocytes (sTILs). Secondly, we measured the expression of PD1 and PD-L1. Lastly, the expression of CD73 on tumor cells, a potential regulatory molecule of immune escape, was analysed.

Methods: Resection specimens of 198 patients, diagnosed with ER/PR negative invasive adenocarcinoma of > 2 cm between 2005 and 2010, were analysed. TILs percentages were analysed according to the international guidelines. Immunohistochemical (IHC) analyses of CD3, CD4, CD8, CD68, CD73, FoxP3 and PD1 were assessed. PD-L1 IHC assay and interpretation was performed by QualTek and a modified proportion score (MPS) was used. The immune parameters were correlated with clinicopathological parameters.

Results: Clinicopathological characteristics are summarized in Table 1. The median expression of the immune parameters ranges from 0 to 10 and is presented in Table 2. Further, sTIL percentages were categorised into three groups, with 10% and 30% as cut-off, which matches with respectively 31%, 50% and 19% of the patients. Applying a cut-off of 1%, only 17% of the samples showed PD-L1 expression while 97% of the samples showed PD-1 expression on TILs. As could be expected a significant positive association was observed between sTILs and CD3, CD4 and CD8, but also with CD68, FoxP3 and PD-L1. No association could be noted between PD-1 expression and any of the other parameters. When taking patient age into account, older patients have significant less sTILs and expression of CD3, CD4, CD8 and FoxP3.

An increase in the fraction of sTILs with 10% was significantly associated with a lower risk of metastasis ([HR] = 0.529, p < 0.01). This also reflects in the observation that an increase in CD3, CD8 and FoxP3 lowers the risk of metastasis ([HR] of respectively 0.940 (p < 0.01), 0.876 (p = 0.02) and 0.658 (p = 0.01)). No significant association between CD73 and the risk of metastasis was observed (p = 0.1098).

Table 1: Clinicopathological informationAge (mean)56,36  N%Histological typeNon special type16382,32Special type3517,68 Molecular type Triple negative14271,72HER2 positive5628,28 Tumour grade 110,512115,56318693,94pT217487,8832311,62410,51pN09748,9917638,382136,573126,06

Table 2: Expression of the different immune parametersVariableMedian (%)IQR (%)Range (%)sTILs105 - 305 - 80CD3105 - 205 - 70CD455 - 55 - 20CD855 - 105 - 60CD68105 - 205 - 80CD7300 - 50 - 90FoxP321 - 20 - 10PD-155 - 50 - 30PD-L100 - 00 - 100

Conclusion: The expression of immune parameters is this cohort of patients was rather low. Only 19% have high number of sTILs (>30%) and PD-L1 expression (>1%) was present in 17% of patients. Moreover, the number of sTILs as well as subtypes of lymphocytes decreases with age. Further, our data show a significant positive association between sTILs, subtypes of lymphocytes (CD3, CD4, CD8, FoxP3), macrophages (CD68) and PD-L1. Lastly, high sTIL count, expression of CD3, CD8 and FoxP3 were associated with a decreased risk of metastasis.

Citation Format: Hanne Vos, Kathleen Lambein, Giuseppe Floris, Bram Mariën, Lieze Berben, Patrick Neven, Hans Wildiers, Ines Nevelsteen, Ann Smeets. Characterization of the tumor microenvironment in a large series of ER/PR negative breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-04-23.

Abstract P4-06-14: Single-cell RNA sequencing to delineate changes in tumor microenvironment induced by immunotherapy

Introduction: Improved understanding of the interplay between the immune system and cancer would lead to more adequate response prediction to immune-checkpoint blockade (ICB) treatment. Furthermore, insight into immune interactions would allow identifying biomarkers for response to ICB. Single-cell RNA sequencing has emerged as a powerful technology to characterize heterogeneity in a large population of cells and opens up opportunities to predict response to therapy.

Purpose: Tracking the effect of a single dose of Pembrolizumab on the tumor microenvironment through single-cell RNA sequencing.

Methods: Single-cell RNA sequencing was performed on tumor tissue of one patient before and 10 days after a 200 mg dose of Pembrolizumab (Keytruda®). Changes in cell (sub)populations were analyzed. Fresh tumor material was obtained from a core needle biopsy at diagnosis and from the resection specimen.Single cell suspensions were converted to barcoded scRNA-seq libraries with the Chromium Single Cell 3' kit with 10X Genomics platform, aiming for an estimated 5,000 cells per library. The libraries were sequenced using HiSeq400. Expression matrices were generated using CellRanger and analyzed by Seurat package. Dimensionality reduction using principle component analysis was applied to identify major cell types and their subtypes.

Results: The analyzed tumor was a grade 3 invasive ductal adenocarcinoma, hormone receptor negative and HER2+ positive, pT2N0M0. Tumor infiltrating lymphocyte (TIL) count was 30% on core biopsy and 50% on resection specimen. We sequenced a total of 9867 transcriptomes at single cell resolution before and after Pembrolizumab treatment, consisting of 5808 and 4049 cells, respectively. Major cell types of the tumor microenvironment were identified by leveraging single-cell transcriptomics analysis. We observed a sharp decrease in cancer cells after treatment (74% versus 25%), which was accompanied by an increase of tumor infiltrating T cells (18% versus 50%). The residual cancer cells after immunotherapy showed a higher expression of the major histocompatibility complex (MHC), MHC-II in particular. In addition, we found enrichment of B-cells and endothelial cells and a downregulation of fibroblasts and myeloid cells. Furthermore, we analyzed subtypes of each cell type. We found a marked increase in cytotoxic CD4 (6% versus 18%) and cytotoxic CD8 cells (4% versus 12%) in the T cell population. These cytotoxic CD8 cells clearly expressed higher PD-1 after immunotherapy. A decrease in CD4 Tregs, naïve CD4 and intermediate CD8 cells was observed and the B cell enrichment after treatment was mainly driven by the increase of follicular B-cells. The increase of endothelial cells was driven by capillary tumor endothelial but not tip cell population, suggesting vessel normalization rather than neo-vascularization.

Conclusion: Single-cell RNA sequencing provides a powerful tool in detecting changes in the tumor microenvironment induced by immunotherapy, and thus offers new opportunities to predict response to immunotherapy. Thirty-three additional patient samples will be analyzed in the near future, with a special focus on T- and B- cell receptor repertoire.

Citation Format: Vos H, Qian J, Floris G, Nevelsteen I, Lambein K, Berben L, Neven P, Wildiers H, Lambrechts D, Smeets A. Single-cell RNA sequencing to delineate changes in tumor microenvironment induced by immunotherapy [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 P4-06-14.

Stromal characteristics are adequate prognosticators for recurrence risk in ductal carcinoma in situ of the breast

BACKGROUND

Ductal carcinoma in situ (DCIS) of the breast constitutes a heterogeneous group of non-obligate precursors for invasive breast cancer. To date, adequate risk stratification is lacking, which is presumed to result in overtreatment. We previously identified myxoid stromal architecture as a potential prognosticator for loco-regional recurrence. In the present study, we investigated the prognostic potential of stromal characteristics.

METHODS

Hematoxylin and eosin stained slides from 211 DCIS patients were reviewed. The following histological features were dichotomously assessed: nuclear grade, DCIS architecture, presence of necrosis, intraductal calcifications, stromal inflammation and myxoid stromal architecture. Loco-regional recurrences constituted the primary endpoint.

RESULTS

Cox regression analysis showed that high nuclear grade, myxoid stromal architecture and moderate to extensive stromal inflammation were significantly associated with decreased recurrence-free survival, independent of radiotherapy. Based on these features, a combined risk score (CRS) was calculated, ranging from zero to three. A high CRS of three was associated with significantly shorter recurrence-free survival. Nineteen patients had a CRS of three, of which three relapsed (15.7%), whereas only one out of 113 patients with a CRS of zero relapsed (0.9%).

CONCLUSIONS

We were able to validate our previously reported findings regarding the prognostic potential of myxoid periductal stroma in an independent DCIS patient cohort. A CRS based on nuclear grade, myxoid stromal architecture and stromal inflammation might facilitate discrimination of low risk from high risk patients. Consequently, the CRS may tailor adjuvant therapy. Future research should investigate whether radiotherapy can be safely omitted in patients with a low CRS.

Dichotomous histopathological assessment of ductal carcinoma in situ of the breast results in substantial interobserver concordance

AIMS

Robust prognostic markers for ductal carcinoma in situ (DCIS) of the breast require high reproducibility and thus low interobserver variability. The aim of this study was to compare interobserver variability among 13 pathologists, in order to enable the identification of robust histopathological characteristics.

METHODS AND RESULTS

One representative haematoxylin and eosin-stained slide was selected for 153 DCIS cases. All pathologists independently assessed nuclear grade, intraductal calcifications, necrosis, solid growth, stromal changes, stromal inflammation, and apocrine differentiation. All characteristics were assessed categorically. Krippendorff's alpha was calculated to assess overall interobserver concordance. Cohen's kappa was calculated for every observer duo to further explore interobserver variability. The highest concordance was observed for necrosis, calcifications, and stromal inflammation. Assessment of solid growth, nuclear grade and stromal changes resulted in lower concordance. Poor concordance was observed for apocrine differentiation. Kappa values for each observer duo identified the 'ideal' cut-off for dichotomisation of multicategory variables. For instance, concordance was higher for 'non-high versus high' nuclear grade than for 'low versus non-low' nuclear grade. 'Absent/mild' versus 'moderate/extensive' stromal inflammation resulted in substantially higher concordance than other dichotomous cut-offs.

CONCLUSIONS

Dichotomous assessment of the histopathological features of DCIS resulted in moderate to substantial agreement among pathologists. Future studies on prognostic markers in DCIS should take into account this degree of interobserver variability to define cut-offs for categorically assessed histopathological features, as reproducibility is paramount for robust prognostic markers in daily clinical practice. A new prognostic index for DCIS might be considered, based on two-tier grading of histopathological features. Future research should explore the prognostic potential of such two-tier assessment.

Accurate detection and quantification of epigenetic and genetic second hits in BRCA1 and BRCA2-associated hereditary breast and ovarian cancer reveals multiple co-acting second hits

BACKGROUND

This study characterizes the second hit spectrum in BRCA1 and BRCA2-associated breast and ovarian cancers at both gene loci to investigate if second hit mechanisms are mutually exclusive or able to coincide within the same tumor.

METHODS

Loss of heterozygosity, somatic point mutations and copy number alterations along with promoter methylation were studied in 56 breast and 15 ovarian cancers from BRCA1 and BRCA2 germline mutation carriers. A mathematical methodology was introduced to quantify the tumor cell population carrying a second hit.

RESULTS

Copy neutral LOH was the most prevalent LOH mechanism in this cohort (BC 69%, OC 67%). However, only 36% of BC and 47% of OC showed LOH in all cancerous cells. Somatic intragenic deletions and methylated subclones were also found in combination with (partial) loss of heterozygosity. Unequivocal deleterious somatic point mutations were not identified in this cohort.

CONCLUSION

Different mechanisms inactivating the wild type allele are present within the same tumor sample at various extents. Results indicate that BRCA1/2-linked breast and ovarian cancer cells are predominantly characterized by LOH, but harbor a complex combination of second hits at various frequencies.

Abstract P3-05-15: PD-1 expression and its correlation with tumour infiltrating lymphocytes and Ki67 in patients with breast cancer

Introduction: Immunotherapy targeting the programmed death-1 (PD-1) checkpoint has resulted in good outcomes in patients with melanoma, non-small cell lung cancer and head and neck cancer. Recent data have showed that patients with ER/PR negative breast cancer might benefit from immunotherapy as well. We investigated PD-1 expression on tumour infiltrating lymphocytes (TILs), the presence of TILs and Ki67. Furthermore, the association of PD-1, TILs and Ki67 with time to metastasis was statistically determined.

Methods: Resection specimens of 284 patients with an ER/PR negative invasive ductal adenocarcinoma of at least 2 cm were analysed. Haematoxylin-eosin staining was performed to determine the percentage of TILs. Subsequently these percentages were divided into three groups: less than 10%, 10%-30% and more than 30% which matches with respectively 30%, 50% and 20% of the patients. PD-1 expression on the TILs of 116 patients and Ki67 expression of 185 patients were assessed using immunohistochemistry.

Results: An increase in the fraction of TILs was significantly associated with a lower risk of metastasis (hazard ratio [HR] = 0.7, 95% CI = 0.6-0.9). PD-1 expression on TILs was observed in 97% of the patients. Three patients had no expression of PD-1, this lack of PD-1 expression significantly increased the risk of metastasis (HR = 5.541, 95% CI = 1.2-25.0). No association could be noted between PD-1 expression and the amount of TILs or Ki67 (p-values of respectively 0.272 and 0.637). Similarly, no association could be noted between Ki67 and the amount of TILs (p-value = 0.1954)

Conclusion: PD-1 was expressed on TILs in patients with breast cancer. Surprisingly, no correlation was found between PD-1 expression and TILs or Ki67. However, an increased amount of TILs was significantly associated with a lower risk of metastasis.

Citation Format: Vos H, Lambein K, Floris G, Nevelsteen I, Smeets A. PD-1 expression and its correlation with tumour infiltrating lymphocytes and Ki67 in patients with breast cancer [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 P3-05-15.

Comparison of HER2 amplification status among breast cancer subgroups offers new insights in pathways of breast cancer progression

Although the prognostic and predictive significance of human epidermal growth factor receptor 2 (HER2) in invasive breast cancer is well established, its role in ductal carcinoma in situ (DCIS) remains unclear. Reports on combined evaluation of both HER2 protein expression and HER2 amplification status in pure DCIS and DCIS adjacent to invasive ductal carcinoma (i.e., admixed DCIS) are scarce. In this study, immunohistochemistry and fluorescence in situ hybridization (FISH) were used to assess HER2 status in 72 cases of pure DCIS, 73 cases of DCIS admixed with invasive ductal carcinoma (IDC), and 60 cases of pure IDC. HER2 copy number-based amplification was present in 49% of pure DCIS, 16% of admixed DCIS, 18% of admixed IDC, and 8% of pure IDC. Amplified pure DCIS with clusters of HER2 signals showed a significantly lower HER2 copy number than amplified admixed DCIS with clusters. Whereas pure DCIS and admixed DCIS presented significant differences, the in situ and invasive component of admixed tumors showed striking similarities regarding mean HER2 and chromosome 17 centromere (CEP17) copy number, grade, and estrogen and progesterone receptor expression. The discrepant prevalence of HER2 amplification among breast cancer subgroups indirectly suggests that HER2 may not play a crucial role in the transition of in situ to invasive breast cancer. The similarities in HER2 amplification status between the in situ and invasive component of admixed tumors hint at a common biological pathway for both components. Our data support the theory that pure DCIS, pure IDC, and admixed lesions have a common progenitor, but can progress as separate lineages.

Abstract P1-03-14: Assessment of stromal characteristics in ductal carcinoma in situ of the breast: An inter-observer variability study

Aim. Ductal carcinoma in situ (DCIS) is considered to be a non-obligate pre-invasive precursor of invasive ductal carcinoma. We previously showed that DCIS with a predominantly myxoid periductal stromal architecture is associated with an increased risk of both overall and invasive recurrence. The aim of this study is to determine a cut-off for the assessment of myxoid stroma and stromal inflammation in DCIS, based on inter-observer variability. Here, preliminary results of the histopathological analysis of 285 DCIS patients are presented, in which the consistency of assessment of stromal features is compared to the reproducibility of other morphological characteristics.

Methods. Hematoxylin/eosin stained tissue sections of 285 DCIS lesions were retrieved from the archives of the Department of Pathology of Leuven University Hospitals, Leuven, Belgium. The following characteristics were independently scored by two pathologists: nuclear grade, intraductal calcifications, extensive comedonecrosis, DCIS architecture, stromal architecture and stromal inflammation. Nuclear grade was scored as low, intermediate or high grade. Intraductal calcifications were scored as absent or present. Extensive comedonecrosis was defined as eosinophilic necrotic debris in >50% of ductal lumina. DCIS architecture was categorized as non-solid or solid, with a cut-off at 50% of ducts presenting with solid growth. Myxoid stroma was defined as loosely arranged collagen fibers interspersed with an amorphous, slightly basophilic substance. Stromal architecture was classified into 4 categories (0%, 1-33%, 33-66% or >66% myxoid stroma). By applying identical cut-offs, stromal inflammation was subdivided into absent, mild, moderate or extensive periductal inflammation. All features were dichotomized, using different cut-offs. Kappa values were determined to assess inter-observer variability.

Results. Nuclear grade was dichotomized as low grade versus intermediate/high grade (κ 0,500), and as grade low/intermediate versus high grade (κ 0,507). The kappa value for scoring myxoid stromal architecture was highest by dichotomization with a cut-off at 33% (κ 0,566), compared to κ 0,454 and κ 0,501 when using 1% and 66% as a cut-off, respectively. A similar analysis for stromal inflammation revealed that the highest kappa value was obtained by dichotomization as 'absent to mild' versus 'moderate to extensive' inflammation (κ 0,724). Dichotomization with cut-offs of 1% and 66% resulted in lower kappa values of κ 0,564 and κ 0,670, respectively. Scores for extensive comedonecrosis showed substantial agreement (κ 0,604). Scores for solid versus non-solid DCIS architecture (κ 0,507), and presence or absence of calcifications (κ 0,664) showed moderate and substantial agreement, respectively.

Conclusions. Adequate prognostic markers require robustness of assessment, i.e. low inter-observer variability and thus high reproducibility. The dichotomous assessment of stromal features in DCIS resulted in similar or even higher kappa values compared to the dichotomous scoring of other histopathological characteristics. This study demonstrates the robustness of dichotomous assessment of both stromal architecture and stromal inflammation.

Citation Format: Van Bockstal M, Lambein K, Smeets A, Nevelsteen I, Neven P, Christiaens M-R, Libbrecht L, Floris G. Assessment of stromal characteristics in ductal carcinoma in situ of the breast: An inter-observer variability study [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 P1-03-14.

Quality of pathology reporting is crucial for cancer care and registration: a baseline assessment for breast cancers diagnosed in Belgium in 2008

OBJECTIVES

Given the crucial role of pathology reporting in the management of breast cancers, we aimed to investigate the quality and variability of breast cancer pathology reporting in Belgium.

MATERIALS AND METHODS

Detailed information on non-molecular and molecular parameters was retrieved from the pathology protocols available at the Belgian Cancer Registry for 10,007 breast cancers diagnosed in Belgium in 2008.

RESULTS

Substantial underreporting was shown for several clinically relevant non-molecular parameters, such as lymphovascular invasion. High-volume laboratories performed only slightly better than others, and analyses at the individual laboratory level showed clear inter-laboratory variability in reporting for all volume categories. Information on ER/PR and HER2 IHC was mentioned in respectively 91.7% and 90.8% of evaluative cases. HER2 ISH data were available for 78.5% of the cases judged to be 2+ for HER2 IHC. For cases with different specimens analysed, discordance between these specimens was highest for HER2, followed by PR. For HER2, results obtained from different laboratories were even less concordant. In addition, inter-laboratory differences were noted in the used ER/PR scoring systems, the proportion of ER-/PR+ cases, and the relation between histological grade and ER/PR positivity. Data on Ki67 were only available for 43.8% of the investigated cases, and showed inconsistent use of cut-off values.

CONCLUSION

Breast pathology reporting in Belgium in 2008 was suboptimal and showed considerable inter-laboratory variability. Synoptic reporting has been proposed as a facilitator towards increased reporting quality and harmonization, but the lack of aligned informatics remains a major hurdle in its concrete implementation.

A nanobody targeting the F-actin capping protein CapG restrains breast cancer metastasis

Introduction

Aberrant turnover of the actin cytoskeleton is intimately associated with cancer cell migration and invasion. Frequently however, evidence is circumstantial, and a reliable assessment of the therapeutic significance of a gene product is offset by lack of inhibitors that target biologic properties of a protein, as most conventional drugs do, instead of the corresponding gene. Proteomic studies have demonstrated overexpression of CapG, a constituent of the actin cytoskeleton, in breast cancer. Indirect evidence suggests that CapG is involved in tumor cell dissemination and metastasis. In this study, we used llama-derived CapG single-domain antibodies or nanobodies in a breast cancer metastasis model to address whether inhibition of CapG activity holds therapeutic merit.

Methods

We raised single-domain antibodies (nanobodies) against human CapG and used these as intrabodies (immunomodulation) after lentiviral transduction of breast cancer cells. Functional characterization of nanobodies was performed to identify which biochemical properties of CapG are perturbed. Orthotopic and tail vein in vivo models of metastasis in nude mice were used to assess cancer cell spreading.

Results

With G-actin and F-actin binding assays, we identified a CapG nanobody that binds with nanomolar affinity to the first CapG domain. Consequently, CapG interaction with actin monomers or actin filaments is blocked. Intracellular delocalization experiments demonstrated that the nanobody interacts with CapG in the cytoplasmic environment. Expression of the nanobody in breast cancer cells restrained cell migration and Matrigel invasion. Notably, the nanobody prevented formation of lung metastatic lesions in orthotopic xenograft and tail-vein models of metastasis in immunodeficient mice. We showed that CapG nanobodies can be delivered into cancer cells by using bacteria harboring a type III protein secretion system (T3SS).

Conclusions

CapG inhibition strongly reduces breast cancer metastasis. A nanobody-based approach offers a fast track for gauging the therapeutic merit of drug targets. Mapping of the nanobody-CapG interface may provide a platform for rational design of pharmacologic compounds.

Distinguishing score 0 from score 1+ in HER2 immunohistochemistry-negative breast cancer: clinical and pathobiological relevance

OBJECTIVES

To investigate the clinical and pathobiological significance of distinguishing score 0 and score 1+ within the group of immunohistochemistry (IHC)-negative invasive breast cancers.

METHODS

We studied HER2 status using both IHC and fluorescence in situ hybridization (FISH) in 150 consecutive breast tumors submitted to our laboratory after a negative IHC result in local testing centers.

RESULTS

We were able to discern a group of score 0 tumors that had a lower HER2 copy number than the group consisting of score 1+ tumors. In contrast with the group of score 1+ tumors, HER2 FISH was consistently negative for both copy number-based and ratio-based tumors without equivocal results.

CONCLUSIONS

In a setting with stringent quality assurance, score 0 and score 1+ tumors emerge as distinct and clinically important subgroups within the HER2 IHC-negative population.

Leiomyomatosis peritonealis disseminata associated with ascites and endometriosis: a case report and review of the literature

We present a case of leiomyomatosis peritonealis disseminata (LPD) and review the literature. LPD is a rare, benign disorder that is characterized by multiple subperitoneal or peritoneal nodules of varying sizes on the omentum and peritoneal surfaces, grossly resembling disseminated carcinoma. It should be differentiated from other peritoneal tumors. It is mostly asymptomatic and diagnosis is often incidental during surgery. One should be aware of the iatrogenic component of this entity. LPD is being documented with increasing frequency. We report the case of a 39-year-old woman with chronic abdominal pain and heavy dysmenorrhea due to endometriosis associated with LPD. She underwent an abdominal hysterectomy with bilateral salpingo-oophorectomy and omentectomy. LPD and endometriosis is a known association. LPD with ascites and endometriosis however has not yet been reported.

Stromal architecture and periductal decorin are potential prognostic markers for ipsilateral locoregional recurrence in ductal carcinoma in situ of the breast

AIMS

The incidence of ductal carcinoma in situ (DCIS) has increased since the introduction of screening mammography. Recurrence prediction is still not accurate, and could be improved by identifying additional prognostic markers. Periductal stroma actively participates in early breast cancer progression. Therefore, the aim of this study was to explore the prognostic potential of stromal characteristics in DCIS.

METHODS AND RESULTS

Histopathological features and hormone receptor/HER2 status were analysed in a first cohort of 65 cases of DCIS with a median follow-up of 112 months. Cox regression analysis revealed that myxoid stromal architecture was significantly associated with increased ipsilateral locoregional recurrence (P = 0.015). Next, we performed immunohistochemical screening of nine stromal proteins in a second cohort of 82 DCIS cases, and correlated their expression with stromal architecture. Because reduced stromal decorin expression correlated most strongly with myxoid stroma (P < 0.001), it was selected for further analysis in the first cohort. Patients with reduced periductal decorin expression had a higher risk of recurrence (P = 0.008). Furthermore, HER2 overexpression was significantly associated with invasive but not with in situ recurrence (P = 0.007).

CONCLUSIONS

Periductal myxoid stroma and reduced periductal decorin expression seem to be prognostic for overall ipsilateral locoregional recurrence in DCIS, whereas HER2 expression might be a more specific biomarker for invasive recurrence.

Radiation-induced myosin IIA expression stimulates collagen type I matrix reorganization

BACKGROUND AND PURPOSE

Extracellular matrix (ECM) reorganization critically contributes to breast cancer (BC) progression and radiotherapy response. We investigated the molecular background and functional consequences of collagen type I (col-I) reorganization by irradiated breast cancer cells (BCC).

MATERIALS AND METHODS

Radiation-induced (RI) col-I reorganization was evaluated for MCF-7/6, MCF-7/AZ, T47D and SK-BR-3 BCC. Phase-contrast microscopy and a stressed matrix contraction assay were used for visualization and quantification of col-I reorganization. Cell-matrix interactions were assessed by the inhibition of β1 integrin (neutralizing antibody 'P5D2') or focal adhesion kinase (FAK; GSK22560098 small molecule kinase inhibitor). The role of the actomyosin cytoskeleton was explored by western blotting analysis of myosin II expression and activity; and by gene silencing of myosin IIA and pharmacological inhibition of the actomyosin system (blebbistatin, cytochalasin D). BCC death was evaluated by propidium iodide staining.

RESULTS

We observed a radiation dose-dependent increase of col-I reorganization by BCC. β1 Integrin/FAK-mediated cell-matrix interactions are essential for RI col-I reorganization. Irradiated BCC are characterized by increased myosin IIA expression and myosin IIA-dependent col-I reorganization. Moreover, RI col-I reorganization by BCC is associated with decreased BCC death, as suggested by pharmacological targeting of the β1 integrin/FAK/myosin IIA pathway.

CONCLUSIONS

Our data indicate the role of myosin IIA in col-I reorganization by irradiated BCC and reciprocal BCC death.

Bone marrow-derived mesenchymal stem cells promote colorectal cancer progression through paracrine neuregulin 1/HER3 signalling

OBJECTIVE

Bone marrow-derived mesenchymal stem cells (BM-MSC) migrate to primary tumours and drive tumour progression. This study aimed to identify the molecular mechanisms associated with these heterotypic cellular interactions and analyse their relevance in colorectal cancer (CRC).

DESIGN

Paracrine interactions of BM-MSC with CRC cells were studied using collagen invasion assays, cell counts, flow cytometric cell-cycle analysis and tumour xenograft models. The role of neuregulin 1 (NRG1) and the human epidermal growth factor receptor (HER) family pathways were investigated using tyrosine kinase assays, mass spectrometry, pharmacological inhibition, antibody-mediated neutralisation and RNA interference. Transmembrane neuregulin 1 (tNRG1), HER2 and HER3 expression was analysed in primary CRC (n=54), adjacent normal colorectal tissues (n=4), liver metastases (n=3) and adjacent normal liver tissues (n=3) by immunohistochemistry.

RESULTS

BM-MSC stimulate invasion, survival and tumorigenesis of CRC through the release of soluble NRG1, activating the HER2/HER3-dependent PI3K/AKT signalling cascade in CRC cells. Similarly, tumour-associated mesenchymal cells (T-MC) in CRC demonstrate high tNRG1 expression, which is significantly associated with advanced Union for International Cancer Control stage (p=0.005) and invasion depth (p=0.04) and decreased 5-year progression-free survival (p=0.01). HER2 and HER3 show membrane localisation in cancer cells of CRC tissue.

CONCLUSION

Paracrine NRG1/HER3 signals initiated by BM-MSC and T-MC promote CRC cell progression, and high tNRG1 expression is associated with poor prognosis in CRC.

Vacuolar H+ ATPase expression and activity is required for Rab27B-dependent invasive growth and metastasis of breast cancer

The secretory Rab27B small GTPase promotes invasive growth and metastasis in estrogen receptor (ER) α-positive breast cancer cells by orchestrating the peripheral targeting of vesicles secreting proinvasive growth regulators. Increased Rab27B expression is associated with poor prognosis in breast cancer patients. The molecular mechanisms of peripheral Rab27B secretory vesicle distribution are poorly understood. Mass spectrometry analysis on green fluorescent protein (GFP)-Rab27B vesicles prepared from GFP-Rab27B transfected MCF-7 human breast cancer cells detected eight subunits of the vacuolar H(+)-ATPase (V-ATPase) and the presence of V0a1 and V0d1 subunits was confirmed by Western blot analysis. Reversible inhibition of V-ATPase activity by bafilomycin A1 or transient silencing of V0a1 or V0d1 subunits demonstrated that V-ATPase controls peripheral localization and size of Rab27B vesicles. V-ATPase expression and activity further controls Rab27B-induced collagen type I invasion, cell-cycle progression and invasive growth in the chorioallantoic membrane assay. In agreement, Rab27B-dependent extracellular heat shock protein90α release and matrix metalloprotease-2 activation is markedly reduced by bafilomycin A1 and transient silencing of V0a1 and V0d1 subunits. Poor prognosis ERα-positive primary breast tumors expressing high levels of Rab27B also expressed multiple V-ATPase subunits and showed a strong cytoplasmic and peripheral V-ATPase V1E expression. In conclusion, inhibiting V-ATPase activity by interfering agents and drugs might be an effective strategy for blocking Rab27B-dependent proinvasive secretory vesicle trafficking in ERα-positive breast cancer patients.

An immunohistochemical analysis of Rab27B distribution in fetal and adult tissue

Regulated secretory pathways coordinated by small Rab GTPases are critically involved in intercellular communications. Here, we report the expression and localization of Rab27B in developing and differentiated epithelial human tissues by immunohistochemistry. Rab27B is poorly expressed in fetal tissues suggesting that several developmental mechanisms involved in epithelial differentiation and functions are mediated by other secretory Rab GTPases, such as Rab27A or Rab3 family members. In adult tissues, Rab27B is expressed in a wide variety of differentiated secretory epithelial cells, including those lining the salivary gland, gastrointestinal, mammary and prostate tracts. The complex pattern of Rab27B expression indicates that dysregulation of Rab27B-mediated secretion may have profound implications for disease pathology.

Analysis of microsatellite instability in gastric mucosa-associated lymphoid tissue lymphoma

In Helicobacter pylori gastritis, constant antigenic stimulation triggers a sustained B-cell proliferation. Errors made during this continuous DNA replication are supposed to be corrected by the DNA mismatch repair mechanism. Failure of this mismatch repair mechanism has been described in hereditary non-polyposis colorectal cancer (HNPCC) and results in a replication error phenotype. Inherent to their instability during replication, microsatellites are the best markers of this replication error phenotype. We aimed to evaluate the role of defects in the DNA mismatch repair (MMR) mechanism and microsatellite instability (MSI) in relation to the most frequent genetic anomaly, translocation t(11;18)(q21;q21), in gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Therefore, we examined 10 microsatellite loci (BAT25, BAT26, D5S346, D17S250, D2S123, TGFB, BAT40, D18S58, D17S787 and D18S69) for instability in 28 patients with MALT lymphomas. In addition, these tumors were also immunostained for MLH1, MSH2, MSH6 and PMS2, as well as screened for the presence of t(11;18)(q21;q21) by real-time polymerase chain reaction (RT-PCR). We found MSI in 5/28 (18%) lymphomas, with MSI occurring in both t(11;18)(q21;q21)-positive and -negative tumors. One tumor displayed high levels of instability, and, remarkably, this was the only case displaying features of a diffuse large B-cell lymphoma. All microsatellite unstable lymphomas showed a loss of MSH6 expression. In conclusion, our data suggest that a MMR-defect may be involved in the development of gastric MALT lymphomas, and that a defect of MSH6 might be associated with those MSI-driven gastric lymphomas.

Identification of a GαGβγ, AKT and PKCα signalome associated with invasive growth in two genetic models of human breast cancer cell epithelial-to-mesenchymal transition

The epithelial-to-mesenchymal transition (EMT) confers an aggressive subtype associated with chemotherapy resistance in epithelial cancers. However, the mechanisms underlying the EMT and its associated signaling dysfunctions are still poorly understood. In two genetic models of MCF-7 breast cancer cells induced to EMT by WISP-2 silencing and Snail transformation, we investigated the status of several signaling elements downstream of G-protein receptors (GPR) and their functional roles in the invasive growth potential. We report that the E-cadherin repressors Slug, Zeb1/2 and Twist are overexpressed in these EMT cells characterized by a triple negative phenotype (loss of estrogen ERα and progesterone PRA/PRB receptors, no HER2 amplification), combined with loss of the alternative GPR30 estrogen receptor and induction of the invasive growth in collagen type I gels. Ectopic Snail expression suppressed WISP-2 transcripts and down-regulated WISP-2 gene promoter expression in transfected cells. Accordingly, WISP-2 transcripts and Wisp-2 protein were depleted in these two convergent models of BC cell EMT. The EMT caused dominance of several proinvasive pathways downstream of GPR, including GαGβγ subunits, PKCα, AKT and c-Jun induction, constitutive activation of the actin-remodeling GTPase Rac1, coupled with growth responses (more cells at S and G2/M phases of the cell cycle), in line with inhibition of the p27kip1/cyclin-dependent kinase CDK3 cascade. RNA interference or selective inhibitors targeting GαGβγ subunits (BIM-46187, gallein), PKCα (Gö6976, MT477, sh-RNAs) and PI3K-AKT (wortmannin) alleviated the invasive phenotype. In contrast, MCF-7 cells in EMT showed signaling independence to inhibitors of HER family tyrosine kinases and the mitogen- and stress-activated protein kinases. Our study suggests that the signaling protagonists GαGβγ, PKCα and PI3K-AKT are promising candidates as predictive molecular biomarkers and therapeutic targets in the management of clinical BC in EMT.

Intensity-modulated arc therapy with cisplatin as neo-adjuvant treatment for primary irresectable cervical cancer. Toxicity, tumour response and outcome

PURPOSE

The goal of this work was to evaluate the feasibility and outcome of intensity-modulated arc therapy ± cisplatin (IMAT ± C) followed by hysterectomy for locally advanced cervical cancer.

PATIENTS AND METHODS

A total of 30 patients were included in the study. The primary tumour and PET-positive lymph node(s) received a simultaneous integrated boost. Four weeks after IMAT ± C treatment, response was evaluated. Resection consisted of hysterectomy with or without lymphadenectomy. Tumour response, acute and late radiation toxicity, postoperative morbidity and outcome were evaluated.

RESULTS

All hysterectomy specimens were macroscopically tumour-free with negative resection margins; pathological complete response was 40%. In 2 patients, one resected lymph node was positive. There was no excess in postoperative morbidity. Apart from two grade 3 hematologic toxicities, no grade 3 or 4 acute radiation toxicity was observed. No grade 3, 1 grade 4 (4%) intestinal, and 4 grade 3 (14%) urinary late toxicities were observed. The 2-year local and regional control rates were 96% and 100%, respectively. The 2-year distant control rate was 92%. Actuarial 2-year progression free survival rate was 89%. Actuarial 1- and 2-year overall survival rates were 96% and 91%, while 3-year overall survival was 84%.

CONCLUSION

Surgery after IMAT ± C is feasible with low postoperative morbidity and radiation toxicity. Local, regional, distant control and survival rates are promising.

P4-18-06: Relationship between Pathological Features, Her2 Protein Expression, and HER2 and CEP17 Copy Numbers in DCIS

Background Previous studies in which HER2 status in ductal carcinoma in situ (DCIS) was evaluated yielded conflicting results. The reported prevalences of HER2 overexpression and amplification vary remarkably. These discrepancies might partly be due to differences in assessment methods, i.e. FISH or immunohistochemistry (IHC) and usage of tissue microarray or whole mount slides. To further investigate this issue, we performed both FISH and IHC for HER2, evaluated HER2 and CEP17 copy numbers and correlated these data with histopathological findings.

Methods 61 DCIS cases were studied, of which 55 pure DCIS and 6 DCIS with micro-invasion. Pathological features were evaluated and included: architecture, nuclear atypia, necrosis, calcifications, stromal inflammation, stromal morphology, extent of lesion, margin width, Van Nuys Prognostic Index and Pinder classification. Her2 IHC and HER2 dual probe FISH analysis were performed and scored according to ASCO/CAP guidelines. HER2/CEP17 ratio and HER2 and CEP17 copy numbers were separately analysed. IHC for estrogen and progesterone receptor (ER and PR) was also performed. Whole mount slides were used for all analyses.

Results 15 cases (25%) were scored negative (1+), 10 cases (16%) equivocal (2+) and 36 cases (59%) positive (3+) using Her2 IHC. According to FISH analysis, 34 of 60 cases (57%) showed HER2 amplification; there was insufficient tissue for FISH analysis in one case.

The amplification status of the DCIS lesions correlated with the IHC score (p&lt;0,001). 30 of all 34 amplified cases were assigned a 3+ IHC score, and remarkably, all these cases showed HER2 clusters on FISH analysis (88%).

Amplified lesions showed more frequently nuclear atypia grade 3 (p=0.0335), extensive comedonecrosis (p=0.002) and stromal inflammation (p=0.003). HER2 amplification correlated with the presence of micro-invasion (p=0.0218)%. There was no correlation with hormone receptor status or other pathological variables.

In the amplified group, high-grade nuclear atypia was associated with a higher mean HER2 copy number (p=0.0026) and HER2/CEP17 ratio (p=0.0356), while this was not the case in the non-amplified group. CEP17 copy numbers did not correlate with nuclear atypia. Conclusions

The correlation between HER2 amplification and adverse pathological features, including micro-invasion and the association in amplified DCIS between HER2 copy number and high-grade nuclear atypia, underscore that HER2 is a driver of DCIS aggressiveness and possibly of recurrence in the form of non-invasive cancer. However, the prevalence of HER2 overexpression, amplification and cluster formation was much higher than in invasive carcinoma, suggesting that HER2 might play a less important role in transition from DCIS to frankly invasive cancer. Further studies should evaluate non-invasive and invasive recurrence of resected DCIS separately.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-18-06.

P1-03-08: Adipose Tissue in Breast Cancer: Not an Idle Bystander but an Active Participant in Breast Cancer Progression

Background: Adipose tissue is a dynamic organ that secretes a plethora of molecules called adipokines. In breast cancer we find a unique situation were genetically changed cells (the cancer cells) are in close contact with adipocytes. Moreover, obesity is a known negative prognostic marker for postmenopausal breast cancer patients. We hypothesize that adipocyte-derived factors influence breast cancer progression.

Materials and methods: Adipose tissue was collected from breast cancer patients undergoing a mastectomy. After macroscopic removal of blood vessels and connective tissue, the adipose tissue was carefully cut into 2–3mm3 pieces and were incubated in specific adipose-tissue culture medium. After 24h, the medium was collected and the quality was checked by determining the concentration of total proteins, leptin, adiponectin, TNFalpha and triglycerides. This conditioned medium of adipose tissue (CM AT) was used for in vitro experimentation with MCF-7 breast cancer cells.

Results: Effect of AT on morphology and aggregation: when MCF-7 cells are grown in a culture flask, they tend to form round compact islands. Under influence of CM AT, the islands form sharp edges, the cells in an island can be counted individually and they show scattering. Importantly, despite the major changes in cellular morphology, CM AT removal rescued the compact island formation of MCF-7 cells. In the slow aggregation assay, cells treated with CM AT (and a subtherapeutic concentration of a neutralizing E-cadherin antibody) lost the ability to form compact aggregates. Furthermore, MCF-7 spheroids placed inside adipose tissue showed massive reorganization into an irregularly shaped mass.

Effect of AT on proliferation: starting from an equal number of cells and counting them every 2 days, it became clear that MCF-7 cells with CM AT had a higher rate of proliferation than MCF-7 cells in control medium. This stimulation of proliferation was confirmed by cell cycle analysis which revealed a doubling of cells in the G2/M phase, and western blot which showed an upregulation of cyclin A and cyclin E, both positive regulators of the cell cycle. Effect of AT on invasion: a 24h collagen type I invasion assay revealed invasive characteristics of MCF-7 cells treated with CM AT while MCF-7 cells in control conditions are round and non-invasive. In contrast, a transwell collagen test over 14 days was not able to show MCF-7 cells invading the collagen gel under influence of CM AT. However, the growth pattern of MCF-7 cells on the collagen gel was clearly disorganised when compared with the control situation.

Conclusion: These findings suggest that adipose tissue-derived factors exert a dramatic selective force on patterning, invasion and growth of MCF-7 breast cancer cells. Unraveling the mechanism behind these observations may provide vital information regarding the link between obesity and poor prognosis in postmenopausal breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-03-08.

Microscopic polyangiitis involving the breast

We report a case of a 76-year-old woman, presenting with a persistent dry cough, subfebrility, arthralgia and myalgia, weight loss and a breast lesion. She has elevated inflammatory parameters, impaired renal function with proteinuria, bilateral lung nodules on computed tomography scan (CT scan) and a suspect lesion on mammography. A diagnosis of microscopic polyangiitis with involvement of the breast is made based on clinical and radiographic findings, with positive auto-immune serology and histological confirmation. Although vasculitis of the breast is uncommon, this case illustrates that when a breast lesion is found, in combination with constitutional symptoms, we should think about the possibility of an anti-Neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis. Therefore it may be important to perform auto-immune serology in these cases before proceeding to major surgery.

Relationship between pathological features, HER2 protein expression and HER2 and CEP17 copy number in breast cancer: biological and methodological considerations

AIMS

A few reports have assessed HER2 status in breast cancer by both dual-probe fluorescence in situ hybridisation (FISH) and immunohistochemistry (IHC) in an unselected and consecutive fashion, but CEP17 and HER2 copy number were not evaluated separately in these studies. Therefore, the aim of this study was to perform FISH testing for HER2 in a large number of breast tumours, irrespective of the IHC scores, which were also determined in all cases.

METHODS

Both FISH and IHC were applied to 200 tumours from 196 consecutive patients who underwent resection of primary breast cancer with the sentinel procedure and/or axillary dissection. Not only the ratio, but also mean HER2 and CEP17 copy number were determined and used in statistical analyses to evaluate relationships between FISH, IHC and clinicopathological features.

RESULTS

The amplification status based solely on HER2 signals was 98% concordant with results of dual-probe FISH. In non-amplified tumours, the mean CEP17 and HER2 copy number correlated, possibly because of cell cycling. Amplified tumours were histopathologically more aggressive than non-amplified tumours, and features of aggressiveness increased with the mean HER2 copy number. In both amplified and non-amplified tumours, a gene dosage effect was observed: an increase in the mean HER2 copy number was associated with a higher IHC score.

CONCLUSIONS

This working method and analysis enabled new insights to be obtained into the pathobiology of HER2 in breast cancer. The findings may be helpful in optimising the methodology of HER2 testing.

Biomarkers ER, PR, HER-2 En Topoisomerase II alpha in Correlation with Response to Neoadjuvant Chemotherapy for Primary Breast Cancer

Background: Neoadjuvant chemotherapy (CT) is widely accepted for patients with primary breast cancer (BC) not eligible for breast conservative surgery (BCS). Docetaxel, when used in combination with or when sequentially added to an anthracycline-based regimen, is active in the adjuvant setting. The objectives of this trial were to assess the activity of sequential anthracycline-docetaxel chemotherapy in the neo-adjuvant setting and to evaluate these markers as predictors of response.Patients and methods: Patients with unilateral BC &gt; 2 cm (with or without positive sentinel lymph node (LN)), adequate liver, kidney and bone marrow function and no evidence of distant metastasis were eligible for enrolment. Patients with stage T4d or inflammatory BC were excluded. Treatment prior to surgery consisted of 4 cycles of Adriamycin (60 mg/m²) plus cyclophosphamide (600 mg/m²) (AC) administered intravenously every 3 weeks (q3wk), followed by 4 cycles of docetaxel (D) (100mg/m²) q3wk. Patients were clinically evaluated after 4 cycles of AC and again after 4 cycles of D. Pathological evaluation was performed after definitive surgery. Hormonal receptor, HER2 and topoisomerase II alpha (topoII) status and tumor grade were evaluated for their ability to predict response to treatment.Results: Fifty-three patients with a mean age of 49 years (range 31-69), were included in this analysis. Mean largest tumor diameter before treatment was 49.1 mm (range 25-90 mm). There were 12 grade 2 and 30 grade 3 tumours representing 46 ductal carcinomas, 5 lobular carcinomas and 2 mixed tumors. Eleven tumors (21%) were not evaluable (NE). LNs were positive in 62% of patients. Forty patients were evaluable for HER-2 and topoII. Thirteen patients (33%) were HER2-positive by immunohistochemistry (IHC) and 11 of these 13 were also HER2-positive by fluorescence in situ hybridization (FISH), 4 patients were topoII positive by FISH. The mean topoII level for FISH-positive patients was 1.83 (CI, 95%, 1.49 to 2.16). There was no increase in the topoII level without HER2 amplification by FISH. Forty-three percent of patients were oestrogen (E) and progesterone (P) receptor (R) positive, 28% were ER and PR negative, and 15% of patients were triple negative. After 4 cycles of AC, a complete reponse (CR) was seen in 17% of patients, partial response (PR) in 53% stable disease (SD) in 26%, and progressive disease (PD) in 4%. After 4 cycles of D the corresponding figures were 30%, 45%, 11% and 2% respectively. Eleven percent of patients were NE. Forty patients (75.5%) had BCS and 13 (24.5%) underwent mastectomy. A correlation was found between HER2 amplification by FISH and topoII amplification: r=0.576 (95% CI, 0.290 to 0.767). ER, PR, tumor grade, HER2 and topoII failed to predict response.Conclusions: Sequential AC followed by D is a highly effective neoadjuvant treatment and permits BCS in more than 75% of patients. There is a significant correlation between HER2 amplification by FISH and topoII levels. Tumor grade, ER, PR, HER2 or topoII were no predictors of response to AC nor D.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2045.

Comparison of miRNA profiles of microdissected Hodgkin/Reed-Sternberg cells and Hodgkin cell lines versus CD77+ B-cells reveals a distinct subset of differentially expressed miRNAs

Classical Hodgkin lymphoma (cHL) is characterized by the presence of malignant Hodgkin and Reed Sternberg (HRS) cells. The scarcity of tumour cells in lymphoma biopsies has hampered genetic analyses of HRS cells, including microRNA (miRNA) expression profiling. We determined the expression of 360 miRNAs in microdissected HRS cells from nine cHL patients. These miRNA profiles were compared to those from four cHL cell lines and CD77+ B-cells, yielding a distinct cHL signature of 12 over- and three underexpressed miRNAs. Our data suggest that miRNAs are implicated in the pathogenesis of Hodgkin lymphoma and prompt further investigations concerning their role in cHL.

The extracellular matrix regulates cancer progression and therapy response: implications for prognosis and treatment

Emerging evidence points towards a key role of the extracellular matrix (ECM) during tumor progression and therapy resistance. Paradoxically, in today's routine of cancer management the ECM is not taken into account. It is the aim of the present review to broaden our understanding of the mechanisms of therapy resistance, taking the ECM as a presumptive central regulator. The stromal ecosystem drives the accumulation of ECM at the invasion front. Therefore, we address the question whether the detection of ECM signatures in histopathology and biofluids may help predicting therapy resistance and determining the prognosis of cancer. Since the ECM is an attractive target for tumor therapy, current therapeutic strategies in preclinical or clinical development will be discussed.