Albrecht Stenzinger

Identification of a population of blood circulating tumor cells from breast cancer patients that initiates metastasis in a xenograft assay.

It has been hypothesized that carcinoma metastasis is initiated by a subpopulation of circulating tumor cells (CTCs) found in the blood of patients. However, although the presence of CTCs is an indicator of poor prognosis in several carcinoma entities, the existence and phenotype of metastasis-initiating cells (MICs) among CTCs has not been experimentally demonstrated. Here we developed a xenograft assay and used it to show that primary human luminal breast cancer CTCs contain MICs that give rise to bone, lung and liver metastases in mice. These MIC-containing CTC populations expressed EPCAM, CD44, CD47 and MET. In a small cohort of patients with metastases, the number of EPCAM+CD44+CD47+MET+ CTCs, but not of bulk EPCAM+ CTCs, correlated with lower overall survival and increased number of metastasic sites. These data describe functional circulating MICs and associated markers, which may aid the design of better tools to diagnose and treat metastatic breast cancer.

The Novel Histologic International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society Classification System of Lung Adenocarcinoma Is a Stage-Independent Predictor of Survival

PURPOSE Our aim was to analyze and validate the prognostic impact of the novel International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) proposal for an architectural classification of invasive pulmonary adenocarcinomas (ADCs) across all tumor stages. PATIENTS AND METHODS The architectural pattern of a large cohort of 500 patients with resected ADCs (stages I to IV) was retrospectively analyzed in 5% increments and classified according to their predominant architecture (lepidic, acinar, solid, papillary, or micropapillary), as proposed by the IASLC/ATS/ERS. Subsequently, histomorphologic data were correlated with clinical data, adjuvant therapy, and patient outcome. RESULTS Overall survival differed significantly between lepidic (78.5 months), acinar (67.3 months), solid (58.1 months), papillary (48.9 months), and micropapillary (44.9 months) predominant ADCs (P = .007). When patterns were lumped into groups, this resulted in even more pronounced differences in survival (pattern group 1, 78.5 months; group 2, 67.3 months; group 3, 57.2 months; P = .001). Comparable differences were observed for overall, disease-specific, and disease-free survival. Pattern and pattern groups were stage- and therapy-independent prognosticators for all three survival parameters. Survival differences according to patterns were influenced by adjuvant chemoradiotherapy; in particular, solid-predominant tumors had an improved prognosis with adjuvant radiotherapy. The predominant pattern was tightly linked to the risk of developing nodal metastases (P < .001). CONCLUSION Besides all recent molecular progress, architectural grading of pulmonary ADCs according to the novel IASLC/ATS/ERS scheme is a rapid, straightforward, and efficient discriminator for patient prognosis and may support patient stratification for adjuvant chemoradiotherapy. It should be part of an integrated clinical, morphologic, and molecular subtyping to further improve ADC treatment.

Detection and Segmentation of Cell Nuclei in Virtual Microscopy Images: A Minimum-Model Approach

Automated image analysis of cells and tissues has been an active research field in medical informatics for decades but has recently attracted increased attention due to developments in computer and microscopy hardware and the awareness that scientific and diagnostic pathology require novel approaches to perform objective quantitative analyses of cellular and tissue specimens. Model-based approaches use a priori information on cell shape features to obtain the segmentation, which may introduce a bias favouring the detection of cell nuclei only with certain properties. In this study we present a novel contour-based “minimum-model” cell detection and segmentation approach that uses minimal a priori information and detects contours independent of their shape. This approach avoids a segmentation bias with respect to shape features and allows for an accurate segmentation (precision = 0.908; recall = 0.859; validation based on ∼8000 manually-labeled cells) of a broad spectrum of normal and disease-related morphological features without the requirement of prior training.

Molecular Diagnostic Profiling of Lung Cancer Specimens with a Semiconductor-Based Massive Parallel Sequencing Approach Feasibility, Costs, and Performance Compared with Conventional Sequencing

In the context of personalized oncology, screening for somatic tumor mutations is crucial for prediction of an individual patients response to therapy. Massive parallel sequencing (MPS) has been suggested for routine diagnostics, but this technology has not been sufficiently evaluated with respect to feasibility, reliability, and cost effectiveness with routine diagnostic formalin-fixed, paraffin-embedded material. We performed ultradeep targeted semiconductor-based MPS (190 amplicons covering hotspot mutations in 46 genes) in a variety of formalin-fixed, paraffin-embedded diagnostic samples of lung adenocarcinoma tissue with known EGFR mutations (n = 28). The samples reflected the typical spectrum of tissue material for diagnostics, including small biopsies and samples with low tumor-cell content. Using MPS, we successfully sequenced all samples, with a mean read depth of 2947 reads per amplicon. High-quality sequence reads were obtained from samples containing ≥10% tumor material. In all but one sample, variant calling identified the same EGFR mutations as were detected by conventional Sanger sequencing. Moreover, we identified 43 additional mutations in 17 genes and detected amplifications in the EGFR and ERBB2 genes. MPS performance was reliable and independent of the type of material, as well as of the fixation and extraction methods, but was influenced by tumor-cell content and the degree of DNA degradation. Using sample multiplexing, focused MPS approached diagnostically acceptable cost rates.

Interobserver variability in the application of the novel IASLC/ATS/ERS classification for pulmonary adenocarcinomas

Recently, a novel classification for pulmonary adenocarcinomas (ADCs) was published, the cornerstone of which is the quantification of growth patterns. Data on reproducibility in the routine diagnostic setting are lacking. 100 constitutive cases of lung ADC resection specimens from our archives were classified independently by five pulmonary pathologists and two residents according to the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification. The most frequent predominant pattern in our cohort was solid (37%), followed by acinar (35%), lepidic (20%), papillary (5%) and micropapillary (3%). &kgr;-values for the denomination of the predominant pattern revealed substantial agreement for pulmonary pathologists (&kgr;=0.44–0.72) and fair agreement for residents (&kgr;=0.38–0.47). Interobserver variability was significantly higher in cases with higher slide numbers (p=0.028) and was considerably reduced after training. Intraobserver variability was low (&kgr;=0.79–0.87). Papillary and micropapillary patterns were the most complicated patterns to evaluate, while evaluation of lepidic and solid tumour growth was straightforward. Our data imply that the novel classification of pulmonary ADC is applicable with acceptable interobserver variability if performed by specifically trained pathologists. Additional efforts are needed to harmonise the application of this novel and clinically important classification scheme of pulmonary ADC.

Increased microtubule assembly rates influence chromosomal instability in colorectal cancer cells

Chromosomal instability (CIN) is defined as the perpetual missegregation of whole chromosomes during mitosis and represents a hallmark of human cancer. However, the mechanisms influencing CIN and its consequences on tumour growth are largely unknown. We identified an increase in microtubule plus-end assembly rates as a mechanism influencing CIN in colorectal cancer cells. This phenotype is induced by overexpression of the oncogene AURKA or by loss of the tumour suppressor gene CHK2, a genetic constitution found in 73% of human colorectal cancers. Increased microtubule assembly rates are associated with transient abnormalities in mitotic spindle geometry promoting the generation of lagging chromosomes and influencing CIN. Reconstitution of proper microtubule assembly rates by chemical or genetic means suppresses CIN and thereby, unexpectedly, accelerates tumour growth in vitro and in vivo. Thus, we identify a fundamental mechanism influencing CIN in cancer cells and reveal its adverse consequence on tumour growth.

Expression of Amphiregulin and EGFRvIII Affect Outcome of Patients with Squamous Cell Carcinoma of the Head and Neck Receiving Cetuximab–Docetaxel Treatment

Purpose: Constitutive activation of epidermal growth factor receptor (EGFR) as a result of gene amplification, mutation, or overexpression of its ligands has been associated with response to EGFR targeting strategies. The role of these molecular mechanisms for the responsiveness of squamous cell carcinoma of the head and neck (SCCHN) to cetuximab-containing regimens remains unknown. Experimental Design: Tumor biopsies from 47 patients, enrolled in a single-arm phase II multicenter study for second-line treatment of recurrent or metastatic SCCHN with cetuximab and docetaxel, were analyzed by immunohistochemistry for expression of EGFR, its deletion variant III (EGFRvIII) and its ligand amphiregulin (AREG). The relation between expression levels and disease control rate (DCR) was evaluated by logistic regression. Association between expression levels, progression-free survival (PFS), and overall survival (OS) was determined by Kaplan–Meier analysis, log-rank test, and uni- and multivariate Cox regression analysis. Results: High expression of EGFR, EGFRvIII, and AREG was detected in 73%, 17%, and 45% of SCCHN cases, respectively. Expression levels of EGFR had no impact on PFS or OS. High expression levels of EGFRvIII were significantly associated with reduced DCR and shortened PFS (HR: 3.3, P = 0.005) but not with OS. Patients with high AREG expression in tumor cells had significantly shortened OS (HR: 2.2, P = 0.002) and PFS (HR 2.2, P = 0.019) compared with patients with low expression score. Multivariate Cox analysis revealed an independent association of AREG and EGFRvIII with PFS but only AREG was an independent prognosticator of OS. Conclusions: High EGFRvIII and AREG expression levels identify SCCHN patients who are less likely to benefit from combination treatment with cetuximab and docetaxel. Clin Cancer Res; 17(15); 5197–204. ©2011 AACR.

mTOR expression and activity patterns in gastroenteropancreatic neuroendocrine tumours

Clinical trials indicate efficacy of drugs inhibiting the mammalian target of rapamycin (mTOR) in the treatment of gastroenteropancreatic neuroendocrine tumours (GEP-NET); however, information on detailed expression and activity patterns of mTOR in these tumours is sparse. We investigated the expression of mTOR and expression as well as phosphorylation of its downstream targets 4EBP1, S6K and eIF4E in a cohort of 99 human GEP-NET by immunohistochemistry. We correlated our findings with clinicopathological variables and patient prognosis. We found that 61, 93, 80, 69, 57 and 79% of GEP-NET were positive for mTOR, 4EBP1, cytoplasmic phospho-4EBP1 (p-4EBP1), nuclear p-4EBP1, phospho-S6K (p-S6K) and phospho-eIF4E (p-eIF4E) respectively. mTOR expression and activity were higher in foregut than in midgut tumours. In foregut tumours, expression of mTOR was higher when distant metastases were present (P=0.035). Strong mTOR activity was associated with higher proliferative capacity. In patients with stage IV midgut tumours, strong p-S6K expression was associated with poor disease-specific survival (P=0.048). In conclusion, mTOR shows considerable variations in expression and activity patterns in GEP-NET in dependence of tumour location and metastatic status. We hypothesise that these differences in mTOR expression and activity might possibly influence response to mTOR inhibitors.

The presence of circulating tumor cells (CTCs) correlates with lymph node metastasis in nonresectable squamous cell carcinoma of the head and neck region (SCCHN)

BACKGROUND The mechanisms regulating tumor cell dissemination in locally advanced squamous cell carcinoma of the head and neck region (SCCHN) are largely unresolved. We assessed the frequency of circulating tumor cells (CTCs), their association with clinicopathologic parameters and their kinetics during radiochemotherapy. PATIENTS AND METHODS Peripheral blood samples from 42 patients with locally advanced SCCHN were included. CTCs were detected using flow cytometric analysis of CD45-epithelial cell adhesion molecule+cytokeratin+ cells and results were validated by nested RT-PCR analysis of circulating epidermal growth factor receptor transcripts. The association between the presence of CTCs and T stage, tumor volume, N stage and human papillomavirus status was evaluated. The influence of radiochemotherapy on CTC numbers was determined. RESULTS CTCs were detected in 18 of 42 SCCHN patients (43%), with a mean ± standard deviation of 1.7 ± 0.9 CTCs per 3.75 ml blood. We observed no significant correlation between the presence of CTCs and T stage or tumor volume. However, a nodal stage of N2b or higher was associated with higher frequency of CTCs. Though concurrent radiochemotherapy reduced their frequency, CTCs persisted during treatment in 20% of cases. CONCLUSIONS Detection of CTCs correlates with regional metastasis in inoperable SCCHN. Further follow-up is needed to evaluate the prognostic significance of CTC detection, in addition to clinical staging of lymph nodes, for regional or distant recurrence.

CYP3A5 mediates basal and acquired therapy resistance in different subtypes of pancreatic ductal adenocarcinoma

Although subtypes of pancreatic ductal adenocarcinoma (PDAC) have been described, this malignancy is clinically still treated as a single disease. Here we present patient-derived models representing the full spectrum of previously identified quasi-mesenchymal (QM-PDA), classical and exocrine-like PDAC subtypes, and identify two markers—HNF1A and KRT81—that enable stratification of tumors into different subtypes by using immunohistochemistry. Individuals with tumors of these subtypes showed substantial differences in overall survival, and their tumors differed in drug sensitivity, with the exocrine-like subtype being resistant to tyrosine kinase inhibitors and paclitaxel. Cytochrome P450 3A5 (CYP3A5) metabolizes these compounds in tumors of the exocrine-like subtype, and pharmacological or short hairpin RNA (shRNA)-mediated CYP3A5 inhibition sensitizes tumor cells to these drugs. Whereas hepatocyte nuclear factor 4, alpha (HNF4A) controls basal expression of CYP3A5, drug-induced CYP3A5 upregulation is mediated by the nuclear receptor NR1I2. CYP3A5 also contributes to acquired drug resistance in QM-PDA and classical PDAC, and it is highly expressed in several additional malignancies. These findings designate CYP3A5 as a predictor of therapy response and as a tumor cell–autonomous detoxification mechanism that must be overcome to prevent drug resistance.