Martin Bak

Vascular grading of angiogenesis: prognostic significance in breast cancer

The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11 years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers was moderately reproduced (κ = 0.59). Vascular grade was significantly associated with axillary node involvement, tumour size, malignancy grade, oestrogen receptor status and histological type. In univariate analyses vascular grade significantly predicted recurrence free survival and overall survival for all patients (P< 0.0001), node-negative patients (P< 0.0001) and node-positive patients (P< 0.0001). Cox multivariate regression analysis showed that vascular grading contributed with independent prognostic value in all patients (P< 0.0001). A prognostic index including the vascular grade had clinical impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer.

Microvessel density compared with the Chalkley count in a prognostic study of angiogenesis in breast cancer patients

Aims:  Evaluation of angiogenesis by intratumoral vessel profiles can be performed by different methods. The aim of this study was to investigate the prognostic value of estimates obtained by the intratumoral microvessel density (MVD) method and then to compare with corresponding estimates obtained by the Chalkley method.

Comparison of Gene Sets for Expression Profiling: Prediction of Metastasis from Low-Malignant Breast Cancer

Purpose: In the low-risk group of breast cancer patients, a subgroup experiences metastatic recurrence of the disease. The aim of this study was to examine the performance of gene sets, developed mainly from high-risk tumors, in a group of low-malignant tumors. Experimental Design: Twenty-six tumors from low-risk patients and 34 low-malignant T2 tumors from patients with slightly higher risk have been examined by genome-wide gene expression analysis. Nine prognostic gene sets were tested in this data set. Results: A 32-gene profile (HUMAC32) that accurately predicts metastasis has previously been developed from this data set. In the present study, six of the eight other gene sets have prognostic power in the low-malignant patient group, whereas two have no prognostic value. Despite a relatively small overlap between gene sets, there is high concordance of classification of samples. This, together with analysis of functional gene groups, indicates that the same pathways may be represented by several of the gene sets. However, the results suggest that low-risk patients may be classified more accurately with gene signatures developed especially for this patient group. Conclusion: Several gene sets, mainly developed in high-risk cancers, predict metastasis from low-malignant cancer.

Classifications within Molecular Subtypes Enables Identification of BRCA1/BRCA2 Mutation Carriers by RNA Tumor Profiling

Pathogenic germline mutations in BRCA1 or BRCA2 are detected in less than one third of families with a strong history of breast cancer. It is therefore expected that mutations still remain undetected by currently used screening methods. In addition, a growing number of BRCA1/2 sequence variants of unclear pathogen significance are found in the families, constituting an increasing clinical challenge. New methods are therefore needed to improve the detection rate and aid the interpretation of the clinically uncertain variants. In this study we analyzed a series of 33 BRCA1, 22 BRCA2, and 128 sporadic tumors by RNA profiling to investigate the classification potential of RNA profiles to predict BRCA1/2 mutation status. We found that breast tumors from BRCA1 and BRCA2 mutation carriers display characteristic RNA expression patterns, allowing them to be distinguished from sporadic tumors. The majority of BRCA1 tumors were basal-like while BRCA2 tumors were mainly luminal B. Using RNA profiles, we were able to distinguish BRCA1 tumors from sporadic tumors among basal-like tumors with 83% accuracy and BRCA2 from sporadic tumors among luminal B tumors with 89% accuracy. Furthermore, subtype-specific BRCA1/2 gene signatures were successfully validated in two independent data sets with high accuracies. Although additional validation studies are required, indication of BRCA1/2 involvement (“BRCAness”) by RNA profiling could potentially be valuable as a tool for distinguishing pathogenic mutations from benign variants, for identification of undetected mutation carriers, and for selecting patients sensitive to new therapeutics such as PARP inhibitors.

Pleomorphic (giant cell) carcinoma of the intestine. An immunohistochemical and electron microscopic study

Pleomorphic (giant cell) carcinomas have been described in the lungs, thyroid, pancreas, and gallbladder. Two pleomorphic carcinomas of the small bowel and two of the large bowel are presented. On light microscopic study, the carcinomas were solid, without squamous or glandular differentiation. The tumors were composed of the following three cell types: gemistocytic (giant) cells, smaller polygonal cells, and spindle cells, with identical immunohistochemical reactions. A panel of monoclonal and polyclonal antibodies was applied. All tumors were found to coexpress keratin and vimentin. A positive reaction for neuron‐specific enolase (NSE) was found in three tumors and a positive reaction for chromogranin was found in one tumor. On electron microscopic study, intracytoplasmic whorls of intermediate filaments were seen in the perinuclear area. Dense core “neurosecretory” granules were rarely seen. Intestinal pleomorphic carcinomas are histologically identical to pulmonary giant cell carcinomas. The prognosis is poor due to early tumor spread, with only a few months of postoperative survival. The pleomorphic carcinomas have some of the differentiation characteristics of carcinoid tumors and are best regarded as poorly differentiated variants of neuroendocrine carcinomas. Cancer 64:2557–2564, 1989.

Prediction of metastasis from low-malignant breast cancer by gene expression profiling

Promising results for prediction of outcome in breast cancer have been obtained by genome wide gene expression profiling. Some studies have suggested that an extensive overtreatment of breast cancer patients might be reduced by risk assessment with gene expression profiling. A patient group hardly examined in these studies is the low‐risk patients for whom outcome is very difficult to predict with currently used methods. These patients do not receive adjuvant treatment according to the guidelines of the Danish Breast Cancer Cooperative Group (DBCG). In this study, 26 tumors from low‐risk patients were examined with gene expression profiling. An intermediate risk group of 34 low‐malignant T2 tumors that fulfilled all other low‐risk criteria than tumor size was included to increase statistical power. A 32‐gene classifier, HUMAC32, was identified and it predicted metastases with 80% sensitivity and 77% specificity. The classifier was also validated in an independent group of high‐risk tumors resulting in comparable performance of HUMAC32 and a 70‐gene classifier developed for this group. Furthermore, the 70‐gene signature was tested in our low‐ and intermediate‐risk samples. The results demonstrated high cross‐platform consistency of the classifiers. Higher performance of HUMAC32 was demonstrated among the low‐malignant cancers compared with the 70‐gene classifier. This suggests that although the metastatic potential to some extend is determined by the same genes in groups of tumors with different characteristics and risk, expression‐based classification specifically developed in low‐risk patients have higher predictive power in this group.

A kinase inhibitor screen identifies Mcl-1 and Aurora kinase A as novel treatment targets in antiestrogen-resistant breast cancer cells

Antiestrogen resistance is a major problem in breast cancer treatment. Therefore, the search for new therapeutic targets and biomarkers for antiestrogen resistance is crucial. In this study, we performed a kinase inhibitor screen on antiestrogen responsive MCF-7 cells and a panel of MCF-7-derived tamoxifen- and fulvestrant-resistant cell lines. Our focus was to identify common and distinct molecular mechanisms involved in tamoxifen- and fulvestrant-resistant cell growth. We identified 18 inhibitors, of which the majority was common for both tamoxifen- and fulvestrant-resistant cell lines. Two compounds, WP1130 and JNJ-7706621, exhibiting prominent preferential growth inhibition of antiestrogen-resistant cell lines, were selected for further studies. WP1130, a deubiquitinase inhibitor, induced caspase-mediated cell death in both tamoxifen- and fulvestrant-resistant cell lines by destabilization of the anti-apoptotic protein Mcl-1. Mcl-1 expression was found upregulated in the antiestrogen-resistant cell lines and depletion of Mcl-1 in resistant cells caused decreased viability. JNJ-7706621, a dual Aurora kinase and cyclin-dependent kinase inhibitor, specifically inhibited growth and caused G2 phase cell cycle arrest of the tamoxifen-resistant cell lines. Knockdown studies showed that Aurora kinase A is essential for growth of the tamoxifen-resistant cells and inhibition of Aurora kinase A resensitized tamoxifen-resistant cells to tamoxifen treatment. Preferential growth inhibition by WP1130 and JNJ-7706621 was also found in T47D-derived tamoxifen-resistant cell lines, pointing at Mcl-1 and Aurora kinase A as potential treatment targets. In addition, tumor samples from 244 estrogen receptor-positive breast cancer patients treated with adjuvant tamoxifen showed that higher expression level of Aurora kinase A was significantly associated with shorter disease-free and overall survival, demonstrating the potential of Aurora kinase A as a biomarker for tamoxifen resistance.

Sentinel Node Localization in Breast Cancer Patients Using Intradermal Dye Injection

In a series of 161 consecutive breast cancer operations, intradermal injection of Patent Blue was used to localize the sentinel node (SN). The surgical localization rate was 60%. Including the blue lymph nodes found by the pathologist, localization rate was 70%. After the first 103 operations, the surgical procedure was changed, resulting in a localization rate of 83%. Ten surgeons participated, but only one had previous experience with SN dissection. The others experienced a steep learning curve. Metastasis was found in 42 of 97 SNs (43%). In 15 cases (36%) metastasis was recognized only after step-sectioning and immunohistochemical staining for cytokeratin. In one case a benign epithelial inclusion was found. The sentinel node was false negative in 9.1% of cases. The consensus from the literature is that the best results are achieved using a combination of dye and isotopic techniques.

High CDK6 Protects Cells from Fulvestrant-Mediated Apoptosis and is a Predictor of Resistance to Fulvestrant in Estrogen Receptor-Positive Metastatic Breast Cancer.

Purpose: Resistance to endocrine therapy in estrogen receptor–positive (ER+) breast cancer remains a major clinical problem. Recently, the CDK4/6 inhibitor palbociclib combined with letrozole or fulvestrant was approved for treatment of ER+ advanced breast cancer. However, the role of CDK4/6 in endocrine resistance and their potential as predictive biomarkers of endocrine treatment response remains undefined. Experimental Design: We investigated the specific role of increased CDK6 expression in fulvestrant-resistant cells by gene knockdown and treatment with palbociclib, and evaluated the effect in cell proliferation, apoptosis, and kinase activity. Furthermore, we evaluated CDK6 expression in metastatic samples from breast cancer patients treated or not with fulvestrant. Results: We found increased expression of CDK6 in two fulvestrant-resistant cell models versus sensitive cells. Reduction of CDK6 expression impaired fulvestrant-resistant cell growth and induced apoptosis. Treatment with palbociclib resensitized fulvestrant-resistant cells to fulvestrant through alteration of retinoblastoma protein phosphorylation. High CDK6 levels in metastatic samples from two independent cohorts of breast cancer patients treated with fulvestrant (N = 45 and 46) correlated significantly with shorter progression-free survival (PFS) on fulvestrant treatment (P = 0.0006 and 0.018), whereas no association was observed in patients receiving other first- or second-/third-line endocrine treatments (N = 68, P = 0.135 and 0.511, respectively). Conclusions: Our results indicate that upregulation of CDK6 may be an important mechanism in overcoming fulvestrant-mediated growth inhibition in breast cancer cells. Patients with advanced ER+ breast cancer exhibiting high CDK6 expression in the metastatic lesions show shorter PFS upon fulvestrant treatment and thus may benefit from the addition of CDK4/6 inhibitors in their therapeutic regimens. Clin Cancer Res; 22(22); 5514–26. ©2016 AACR.

Intratumor Genetic Heterogeneity of Breast Carcinomas as Determined by Fine Needle Aspiration and TaqMan Low Density Array

Background: Gene expression profiling is thought to be an important tool in determining treatment strategies for breast cancer patients. Tissues for such analysis may at a preoperative stage be obtained, by fine needle aspiration (FNA) allowing initiation of neoadjuvant treatment. To evaluate the extent of the genetic heterogeneity within primary breast carcinomas, we examined whether a gene expression profile obtained by FNA was representative of the tumor. Methods: Tumors from 12 consecutive cases of early predominantly estrogen receptor positive (ER+) breast cancer patients undergoing primary surgery were split in halves and FNAs were obtained from each half. A tissue biopsy of the tumors was also snap-frozen for comparison. Non-amplified RNA was investigated by the novel qRT-PCR-based technique, Low Density Array (LDA) using 4 reference genes and 44 target genes. Results: Comparison of gene expression at the single gene level in the two FNA samples from each tumor demonstrated various degrees of heterogeneity. However, compared as gene expression profiles, intratumor correlations for 9/12 patients were high and these pairs could in a theoretical blinding of all the FNAs be correctly matched by statistical analysis. High correlations between the gene profiles of tumor FNAs and tissue biopsies from the same patient were observed for all patients. A cluster analysis identified clustering of both the two FNAs and the tissue biopsy of the same 9 patients. Conclusion: The overall genetic heterogeneity of breast carcinomas, as sampled by FNA, does not prohibit generation of useful gene profiles for treatment decision making. However, sampling and analysis strategies should take heterogeneity within a tumor, and varying heterogeneity amongst the single genes, into account.