Andreas Seeber

Loss of membranous expression of the intracellular domain of EpCAM is a frequent event and predicts poor survival in patients with pancreatic cancer

Epithelial cell adhesion molecule (EpCAM) is a widely used immunohistochemical marker for epithelial human malignancies. Antibodies to target EpCAM are usually directed against its ectodomain (EpEX), but do not detect the intracellular domain (EpICD). The aim of this study was to compare membranous EpEX versus EpICD expression by immunohistochemistry.

The role of EpCAM in physiology and pathology of the epithelium

Epithelial Cell Adhesion Molecule (EpCAM) has been discovered as one of the first tumor-specific antigens overexpressed in epithelial cancer. The present review focuses on the role of EpCAM in physiology and homeostasis of epithelia. Recent research pointed to a close interaction of EpCAM with other cell-cell contact molecules like E-cadherin and claudins and an intimate crosstalk with Wnt and TGF-beta signaling in the regulation of cell growth. Moreover, EpCAM has been shown to modulate trans-epithelial migration processes of white blood cells. Mutations of the EpCAM gene lead to disturbances of epithelial homeostasis and cellular differentiation from the stem cell compartment. In the intestinal tract EpCAM mutations contribute to congenital tufting enteropathy. Regarding tumorigenesis EpCAM can act as an oncogene still depending on additional driver mutations and epithelial phenotype of tumor cells. Tumor cells display increased EpCAM expression that often correlates with the loss of strict basolateral localization. Many tumors show enhanced regulated intramembrane proteolysis (RIP) of EpCAM and loose EpCAM expression under conditions of epithelial to mesenchymal transition. The resulting extracellular EpEX and intracellular EpICD fragments mediate proliferative signals to the cell. Resulting fragments can be validated either by sensitive enzyme-linked immune-sandwich assays (EpEX) or by immunohistochemistry (EpICD). The present review gives an overview on the detection of EpCAM fragments as predictive markers for disease progression and survival of cancer patients.

Expression of EpCAM MF and EpCAM MT variants in human carcinomas

Aims Regulated intramembrane proteolysis has been shown to be an important mechanism for oncogenic activation of epithelial cell adhesion molecule (EpCAM) through nuclear translocation of the intracellular domain EpICD. Recent studies have identified new membrane-bound EpCAM variants. To evaluate the prevalence of two membranous EpCAM variants in human tumours, we performed a large-scale expression analysis using specific antibodies against the extracellular domain EpEX (MOC-31 clone) and the intracellular domain EpICD (9-2 clone) of the EpCAM antigen by immunohistochemistry. Material and methods Two multi-tissue microarrays (TMA) series containing 1564 tissue samples each of 53 different histological tumour types were stained and compared. One TMA was stained for EpEX and one for EpICD. Membranous full-length EpCAM (EpCAMMF) expression in tissues was defined by the expression of EpEX and EpICD, while the truncated variant of EpCAM (EpCAMMT) was characterised by a significant loss of membranous EpICD expression compared with EpEX expression. Results We defined tumours with high EpCAMMT expression (ie, cancers of the endometrium and bladder), tumours with intermediate (ie, gastric, pancreatic, colorectal and oesophageal cancer) and tumours with low rates of expression of the EpCAMMT variant (ie, lung, ovarian, gallbladder, breast and prostate cancer). Conclusions Our results indicate that loss of membranous EpICD expression is a common event in human epithelial carcinomas, arguing for the expression of different degrees of EpCAMMF and EpCAMMT variants across the most important tumour entities. Future studies evaluating the prognostic and predictive role of these variants in human malignancies, especially in patients treated with EpCAM-specific antibodies, are clearly warranted.

Expression of EpCAMMF and EpCAMMT variants in human carcinomas

Aims Regulated intramembrane proteolysis has been shown to be an important mechanism for oncogenic activation of epithelial cell adhesion molecule (EpCAM) through nuclear translocation of the intracellular domain EpICD. Recent studies have identified new membrane-bound EpCAM variants. To evaluate the prevalence of two membranous EpCAM variants in human tumours, we performed a large-scale expression analysis using specific antibodies against the extracellular domain EpEX (MOC-31 clone) and the intracellular domain EpICD (9-2 clone) of the EpCAM antigen by immunohistochemistry. Material and methods Two multi-tissue microarrays (TMA) series containing 1564 tissue samples each of 53 different histological tumour types were stained and compared. One TMA was stained for EpEX and one for EpICD. Membranous full-length EpCAM (EpCAMMF) expression in tissues was defined by the expression of EpEX and EpICD, while the truncated variant of EpCAM (EpCAMMT) was characterised by a significant loss of membranous EpICD expression compared with EpEX expression. Results We defined tumours with high EpCAMMT expression (ie, cancers of the endometrium and bladder), tumours with intermediate (ie, gastric, pancreatic, colorectal and oesophageal cancer) and tumours with low rates of expression of the EpCAMMT variant (ie, lung, ovarian, gallbladder, breast and prostate cancer). Conclusions Our results indicate that loss of membranous EpICD expression is a common event in human epithelial carcinomas, arguing for the expression of different degrees of EpCAMMF and EpCAMMT variants across the most important tumour entities. Future studies evaluating the prognostic and predictive role of these variants in human malignancies, especially in patients treated with EpCAM-specific antibodies, are clearly warranted.

Prostate cancer changes in clinical presentation and treatments in two decades: an Italian population-based study

INTRODUCTION The incidence of prostate cancer is on the rise in many industrialised countries, including Italy, most likely because of the spread of PSA testing. In Italy, prostate cancer mortality has been dropping since 2000, but it is difficult to understand whether PSA testing is the main reason, considering the role of treatment in prognosis. The objectives of this study were: (1) to describe Italian trends of prostate cancer risk categories and corresponding changes in treatment patterns and (2) to interpret changes in survival over time. METHODS We made a retrospective observational study using population-based cancer registries. We examined two periods, 1996-1999 and 2005-2007, analysing the distribution of patients among risk groups and treatment changes in those intervals. We estimated 7- and 15-year relative survival with the cohort approach, Ederer II method. We analysed 4635 cases. RESULTS There was downward risk migration from the first to the second period. In patients younger than 75 years, there was an increase in radical prostatectomy but not radiotherapy; patients older than 75 years rarely had treatment with radical intent. We noted an improvement of prostate cancer survival in the high-risk group. CONCLUSION These findings raise several questions: the possible overtreatment of low-risk patients undergoing radical treatment; the utility of more aggressive treatment for elderly patients with high-risk disease; and the importance of a multidisciplinary clinical approach to ensure multiple and alternative treatment options. The increase in survival, with the decrease in mortality, suggests an effect of radical treatments on prognosis.

Detection of soluble EpCAM (sEpCAM) in malignant ascites predicts poor overall survival in patients treated with catumaxomab

EpCAM is an attractive target for cancer therapy and the EpCAM-specific antibody catumaxomab has been used for intraperitoneal treatment of EpCAM-positive cancer patients with malignant ascites. New prognostic markers are necessary to select patients that mostly benefit from catumaxomab. Recent data showed that soluble EpCAM (sEpCAM) is capable to block the effect of catumaxomab in vitro. This exploratory retrospective analysis was performed on archived ascites samples to evaluate the predictive role of sEpCAM in catumaxomab-treated patients. Sixty-six catumaxomab-treated patients with an available archived ascites sample were included in this study and tested for sEpCAM by sandwich ELISA. All probes were sampled before treatment start and all patients received at least one catumaxomab infusion. Overall survival, puncture-free survival and time to next puncture were compared between sEpCAM-positive and -negative patients. We detected sEpCAM in ascites samples of 9 patients (13.6%). These patients showed a significantly shorter overall survival. The prognostic significance of sEpCAM in ascites was particularly strong in patients with ovarian cancer. Puncture-free survival and time to next puncture were not significantly different between sEpCAM-positive and -negative patients. We propose sEpCAM in malignant ascites as a potential predictive marker in cancer patients treated with catumaxomab. Prospective studies with larger patients samples are urgently needed to confirm these findings and studies testing dose-intensified catumaxomab in patients with sEpCAM-positive ascites should be envisaged.

Soluble EpCAM levels in ascites correlate with positive cytology and neutralize catumaxomab activity in vitro

BackgroundEpCAM is highly expressed on membrane of epithelial tumor cells and has been detected as soluble/secreted (sEpCAM) in serum of cancer patients. In this study we established an ELISA for in vitro diagnostics to measure sEpCAM concentrations in ascites. Moreover, we evaluated the influence of sEpCAM levels on catumaxomab (antibody) - dependent cellular cytotoxicity (ADCC).MethodsAscites specimens from cancer patients with positive (C+, n = 49) and negative (C-, n = 22) cytology and ascites of patients with liver cirrhosis (LC, n = 31) were collected. All cell-free plasma samples were analyzed for sEpCAM levels with a sandwich ELISA system established and validated by a human recombinant EpCAM standard for measurements in ascites as biological matrix. In addition, we evaluated effects of different sEpCAM concentrations on catumaxomab-dependent cell-mediated cytotoxicity (ADCC) with human peripheral blood mononuclear cells (PBMNCs) and human tumor cells.ResultsOur ELISA showed a high specificity for secreted EpCAM as determined by control HEK293FT cell lines stably expressing intracellular (EpICD), extracellular (EpEX) and the full-length protein (EpCAM) as fusion proteins. The lower limit of quantification was 200 pg/mL and the linear quantification range up to 5,000 pg/mL in ascites as biological matrix. Significant levels of sEpCAM were found in 39% of C+, 14% of C- and 13% of LC ascites samples. Higher concentrations of sEpCAM were detectable in C+ (mean: 1,015 pg/mL) than in C- (mean: 449 pg/mL; p = 0.04) or LC (mean: 326 pg/mL; p = 0.01). Soluble EpCAM concentration of 1 ng/mL significantly inhibited ADCC of PBMNCs on EpCAM overexpressing target cells.ConclusionElevated concentrations of sEpCAM can be found in a subgroup of C+ and also in a small group of C- patients. We consider that sEpCAM levels in different tumor entities and individual patients should be evaluated prior to applying anti-EpCAM antibody-based cancer therapies, since sEpCAM neutralizes catumaxomab activity, making therapy less efficient.

High IDO-1 expression in tumor endothelial cells is associated with response to immunotherapy in metastatic renal cell carcinoma

Nivolumab belongs to the standard therapy in the second‐line setting of metastatic renal cell carcinoma (mRCC). Although deep and long‐lasting responses are seen in some patients, the majority of patients will further progress. PD‐L1 is still under critical evaluation as a predictive biomarker. Thus, more accurate biomarkers are clearly warranted. Here, we investigated for the first time the predictive role of IDO‐1, a negative immune‐regulatory molecule, on clear cell RCC tissues of 15 patients undergoing nivolumab therapy. IDO‐1 and other immune inhibitory molecules (PD‐L1, PD‐L2, FOXP3) as well as immune cell subsets (CD3, CD4 and CD8) were measured on formalin‐fixed, paraffin‐embedded sections of RCC specimens by immunohistochemistry. IDO‐1 was predominantly expressed in tumor endothelial cells, and was totally absent from tumor cells itself. IDO‐1 overexpression (>10%) could be detected more frequently in responders (100%, n = 6/6) compared to non‐responders (33.3%, n = 3/9; P = .028), resulting in a better progression‐free survival during immunotherapy (IDO‐1 ≤ 10% vs >10%, median: 3.5 vs not estimated (NE) months, P = .01 by log‐rank test). In addition, IDO‐1 was positively correlated with CD8+ T cell expression (rs = .691, P = .006). PD‐L1 expression on tumor cells was negative in 13 (86.7%) of 15 patients, irrespective of therapeutic response (responders vs non‐responders: 83.3% vs 88.9%). No differences were noticed in the PD‐L1 expression on tumor‐infiltrating immune cells (PD‐L1 < 1% in 66.7% of both responders and non‐responders). In contrast to PD‐L1, these results suggest that IDO‐1 may be a more promising predictive biomarker for response to immune‐based cancer therapy in mRCC.

Targeted Therapy of Colorectal Cancer.

Over the past decades, considerable progress has been made in the management of colorectal cancer (CRC), leading to a significant improvement in overall survival. Although part of this success has been rightly attributed to aggressive surgical management and advances in other adjunct treatments, our understanding of the pathogenesis of CRC and emergence of newer molecular targets for colon cancer has created a powerful impact. In this review article, we will discuss various targeted therapies in the management of metastatic CRC (mCRC). In particular, vascular endothelial growth factor (VEGF)- and epidermal growth factor receptor (EGFR)-targeting monoclonal antibodies have become integral components of the first-line treatment strategies for mCRC. Newer agents on the horizon soon to be incorporated in clinical practice will be briefly reviewed as well. Currently, the only predictive biomarker for treatment selection in patients with mCRC is tumor RAS mutational status.

Predominant expression of truncated EpCAM is associated with a more aggressive phenotype and predicts poor overall survival in colorectal cancer.

Regulated intramembrane proteolysis (RIP) has been shown to be an important mechanism for oncogenic activation of EpCAM through nuclear translocation of the intracellular domain EpICD. Recently, we identified two different membranous EpCAM variants namely EpCAMMF (full‐length) and EpCAMMT (truncated) to be expressed in the majority of human epithelial tumors. The aim of our study was to evaluate the potential role of these two protein variants as additional prognostic biomarkers in colorectal cancer. In most studies only one antibody targeting the extracellular domain of EpCAM (EpEX) has been used, whereas in the present study additionally an antibody which detects the intracellular domain (EpICD) was applied to discriminate between different EpCAM variants. Using immunohistochemistry, we analyzed the expression of EpCAMMF and EpCAMMT variants in 640 patients with colorectal cancer and determined their correlations with other prognostic factors and clinical outcome. A statistically significant association was observed for EpCAMMT with advanced tumor stage (p < 0.001), histological grade (p = 0.01), vascular (p < 0.001) and marginal (p = 0.002) invasion. Survival analysis demonstrated reduced overall survival (p < 0.004) in patients with tumors expressing the EpCAMMT phenotype when compared to patients with tumors expressing the EpCAMMF variant. In conclusion, this study for the first time indicates that expression of EpCAMMT is associated with a more aggressive phenotype and predicts poor survival in patients with colorectal cancer.