Stratifying esophago-gastric cancer treatment using a patient-derived organoid-based threshold

BACKGROUND AND AIMS

This study sought to determine the value of patient-derived organoids (PDOs) from esophago-gastric adenocarcinoma (EGC) for response prediction to neoadjuvant chemotherapy (neoCTx).

METHODS

Endoscopic biopsies of patients with locally advanced EGC (n = 120) were taken into culture and PDOs expanded. PDOs' response towards the single substances of the FLOT regimen and the combination treatment were correlated to patients' pathological response using tumor regression grading. A classifier based on FLOT response of PDOs was established in an exploratory cohort (n = 13) and subsequently confirmed in an independent validation cohort (n = 13).

RESULTS

EGC PDOs reflected patients' diverse responses to single chemotherapeutics and the combination regimen FLOT. In the exploratory cohort, PDOs response to single 5-FU and FLOT combination treatment correlated with the patients' pathological response (5-FU: Kendall's τ = 0.411, P = 0.001; FLOT: Kendall's τ = 0.694, P = 2.541e-08). For FLOT testing, a high diagnostic precision in receiver operating characteristic (ROC) analysis was reached with an AUCROC of 0.994 (CI 0.980 to 1.000). The discriminative ability of PDO-based FLOT testing allowed the definition of a threshold, which classified in an independent validation cohort FLOT responders from non-responders with high sensitivity (90%), specificity (100%) and accuracy (92%).

CONCLUSION

In vitro drug testing of EGC PDOs has a high predictive accuracy in classifying patients' histological response to neoadjuvant FLOT treatment. Taking into account the high rate of successful PDO expansion from biopsies, the definition of a threshold that allows treatment stratification paves the way for an interventional trial exploring PDO-guided treatment of EGC patients.

Epitope base editing CD45 in hematopoietic cells enables universal blood cancer immune therapy

In the absence of cell surface cancer-specific antigens, immunotherapies such as chimeric antigen receptor (CAR) T cells, monoclonal antibodies, or bispecific T cell engagers typically target lineage antigens. Currently, such immunotherapies are individually designed and tested for each disease. This approach is inefficient and limited to a few lineage antigens for which the on-target/off-tumor toxicities are clinically tolerated. Here, we sought to develop a universal CAR T cell therapy for blood cancers directed against the pan-leukocyte marker CD45. To protect healthy hematopoietic cells, including CAR T cells, from CD45-directed on-target/off-tumor toxicity while preserving the essential functions of CD45, we mapped the epitope on CD45 that is targeted by the CAR and used CRISPR adenine base editing to install a function-preserving mutation sufficient to evade CAR T cell recognition. Epitope-edited CD45 CAR T cells were fratricide resistant and effective against patient-derived acute myeloid leukemia, B cell lymphoma, and acute T cell leukemia. Epitope-edited hematopoietic stem cells (HSCs) were protected from CAR T cells and, unlike CD45 knockout cells, could engraft, persist, and differentiate in vivo. Ex vivo epitope editing in HSCs and T cells enables the safe and effective use of CD45-directed CAR T cells and bispecific T cell engagers for the universal treatment of hematologic malignancies and might be exploited for other diseases requiring intensive hematopoietic ablation.

Type I Interferon Signaling via the EGR2 Transcriptional Regulator Potentiates CAR T Cell-Intrinsic Dysfunction

Chimeric antigen receptor (CAR) T cell therapy has shown promise in treating hematologic cancers, but resistance is common and efficacy is limited in solid tumors. We found that CAR T cells autonomously propagate epigenetically programmed type I interferon signaling through chronic stimulation, which hampers antitumor function. EGR2 transcriptional regulator knockout not only blocks this type I interferon-mediated inhibitory program but also independently expands early memory CAR T cells with improved efficacy against liquid and solid tumors. The protective effect of EGR2 deletion in CAR T cells against chronic antigen-induced exhaustion can be overridden by interferon-β exposure, suggesting that EGR2 ablation suppresses dysfunction by inhibiting type I interferon signaling. Finally, a refined EGR2 gene signature is a biomarker for type I interferon-associated CAR T cell failure and shorter patient survival. These findings connect prolonged CAR T cell activation with deleterious immunoinflammatory signaling and point to an EGR2-type I interferon axis as a therapeutically amenable biological system.

SIGNIFICANCE

To improve CAR T cell therapy outcomes, modulating molecular determinants of CAR T cell-intrinsic resistance is crucial. Editing the gene encoding the EGR2 transcriptional regulator renders CAR T cells impervious to type I interferon pathway-induced dysfunction and improves memory differentiation, thereby addressing major barriers to progress for this emerging class of cancer immunotherapies. This article is highlighted in the In This Issue feature, p. 1501.

Engineering the next-generation of CAR T-cells with CRISPR-Cas9 gene editing

Chimeric Antigen Receptor (CAR) T-cells represent a breakthrough in personalized cancer therapy. In this strategy, synthetic receptors comprised of antigen recognition, signaling, and costimulatory domains are used to reprogram T-cells to target tumor cells for destruction. Despite the success of this approach in refractory B-cell malignancies, optimal potency of CAR T-cell therapy for many other cancers, particularly solid tumors, has not been achieved. Factors such as T-cell exhaustion, lack of CAR T-cell persistence, cytokine-related toxicities, and bottlenecks in the manufacturing of autologous products have hampered the safety, effectiveness, and availability of this approach. With the ease and accessibility of CRISPR-Cas9-based gene editing, it is possible to address many of these limitations. Accordingly, current research efforts focus on precision engineering of CAR T-cells with conventional CRISPR-Cas9 systems or novel editors that can install desired genetic changes with or without introduction of a double-stranded break (DSB) into the genome. These tools and strategies can be directly applied to targeting negative regulators of T-cell function, directing therapeutic transgenes to specific genomic loci, and generating reproducibly safe and potent allogeneic universal CAR T-cell products for on-demand cancer immunotherapy. This review evaluates several of the ongoing and future directions of combining next-generation CRISPR-Cas9 gene editing with synthetic biology to optimize CAR T-cell therapy for future clinical trials toward the establishment of a new cancer treatment paradigm.

Abstract 2852: A gene activating in vivo screen identifies EBAG9 as novel metastasis regulator in human colorectal cancer

As colorectal cancer (CRC) mortality remains high due to metastatic spread in patients with advanced disease stages, we here aimed at identifying novel metastasis regulators in CRC and at understanding their mechanism of action. In CRC, tumor progression and metastasis formation are driven by cells that possess tumor-initiating cell (TIC) activity. We therefore employed a collection of primary patient-derived CRC tumor spheroid cultures (TSC) that are enriched for cells with TIC activity to perform a gene activating in vivo screen, intending to identify genes that enhance metastasis formation. To this end, TSC (n=4) were transduced with a lentiviral trapping vector that integrates into the genome and thereby drives the overexpression of genes located in the vicinity of the integration site (IS). Transduced TSC were then serially transplanted under the kidney capsule of immunodeficient mice (NSG) and monitored for the induction of metastasis formation. Analysis of lentiviral IS by linear amplification-mediated (LAM)-PCR revealed an enrichment of an IS within the gene locus of Estrogen Receptor Binding Site Associated Antigen 9 (EBAG9) in metastases. RNA sequencing confirmed the trapping vector mediated upregulation of a truncated version of the EBAG9 gene (exon 5-7), which strongly suggested a contribution of EBAG9 to metastatic spread. To validate these findings, both the truncated (TR) as well as the physiologically occurring full length (FL) EBAG9 gene were overexpressed in TSC (n=4) and serially transplanted into NSG mice. In addition to an augmentation in metastasis upon EBAG9 overexpression compared to controls (FL: 1.4-fold, TR: 2.4-fold), we also detected the occurrence of lymphogenous metastases when EBAG9 levels were increased, indicating that EBAG9 not only contributes to metastatic spread but also modulates tropism. To further characterize the underlying processes, global gene and protein expression analyses were performed in primary TSC as well as in the CRC cell line DLD1. Compared to control transduced cells, EBAG9 overexpression induced expression changes in cell adhesion and microtubule molecules, which led us to investigate cell migration and adhesion as potential contributing mechanisms to metastasis formation. We here observed an increase both in cell migration as well as in adhesion to the extracellular matrix protein collagen I upon EBAG9 overexpression in DLD1. Interestingly, DLD1 adhesion to lymphatic endothelial cells was significantly higher in EBAG9 FL (p=0.008) and EBAG9 TR (p=0.016) overexpressing cells, underscoring the role of EBAG9 in tropism modulation. In summary, we here identified EBAG9 as novel metastasis regulator in CRC which will not only contribute to a better mechanistic understanding of metastatic spread but also to the development of novel future strategies for preventing and targeting advanced disease stages.

Citation Format: Karin Laaber, Taronish D. Dubash, Anna Maria Melzer, Tania Christiansen, Nati Ha, Benedikt Brors, Martin Schneider, Friederike Herbst, Hanno Glimm, Claudia R. Ball. A gene activating in vivo screen identifies EBAG9 as novel metastasis regulator in human colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2852.

Degradation of CCNK/CDK12 is a druggable vulnerability of colorectal cancer

Novel treatment options for metastatic colorectal cancer (CRC) are urgently needed to improve patient outcome. Here, we screen a library of non-characterized small molecules against a heterogeneous collection of patient-derived CRC spheroids. By prioritizing compounds with inhibitory activity in a subset of-but not all-spheroid cultures, NCT02 is identified as a candidate with minimal risk of non-specific toxicity. Mechanistically, we show that NCT02 acts as molecular glue that induces ubiquitination of cyclin K (CCNK) and proteasomal degradation of CCNK and its complex partner CDK12. Knockout of CCNK or CDK12 decreases proliferation of CRC cells in vitro and tumor growth in vivo. Interestingly, sensitivity to pharmacological CCNK/CDK12 degradation is associated with TP53 deficiency and consensus molecular subtype 4 in vitro and in patient-derived xenografts. We thus demonstrate the efficacy of targeted CCNK/CDK12 degradation for a CRC subset, highlighting the potential of drug-induced proteolysis for difficult-to-treat types of cancer.

The balance between the intronic miR-342 and its host gene Evl determines hematopoietic cell fate decision

Protein-coding and non-coding genes like miRNAs tightly control hematopoietic differentiation programs. Although miRNAs are frequently located within introns of protein-coding genes, the molecular interplay between intronic miRNAs and their host genes is unclear. By genomic integration site mapping of gamma-retroviral vectors in genetically corrected peripheral blood from gene therapy patients, we identified the EVL/MIR342 gene locus as a hotspot for therapeutic vector insertions indicating its accessibility and expression in human hematopoietic stem and progenitor cells. We therefore asked if and how EVL and its intronic miRNA-342 regulate hematopoiesis. Here we demonstrate that overexpression (OE) of Evl in murine primary Lin^- Sca1⁺ cKit⁺ cells drives lymphopoiesis whereas miR-342 OE increases myeloid colony formation in vitro and in vivo, going along with a profound upregulation of canonical pathways essential for B-cell development or myelopoietic functions upon Evl or miR-342 OE, respectively. Strikingly, miR-342 counteracts its host gene by targeting lymphoid signaling pathways, resulting in reduced pre-B-cell output. Moreover, EVL overexpression is associated with lymphoid leukemia in patients. In summary, our data show that one common gene locus regulates distinct hematopoietic differentiation programs depending on the gene product expressed, and that the balance between both may determine hematopoietic cell fate decision.

Abstract 1491: Transcriptional heterogeneity identifies functional states of tumor-initiating cell differentiation in human colorectal cancer

Tumor progression in colorectal cancer (CRC) is driven by a subpopulation of cells with tumor-initiating cell (TIC) activity. In the past, bulk experiments provided strong evidence for functional heterogeneity of the CRC TIC compartment with distinct types of TICs driving CRC progression. However, in these retrospective experiments direct assignment of functional states to individual functionally relevant cell types in CRC has not been possible.

We here asked whether functional states of individual cells can be assigned to specific CRC cell subpopulations. Therefore, 4,663 single-cell profiles were generated by single-cell RNA-sequencing (scRNA-seq) of patient-derived CRC spheroid cultures (n=12). Non-negative matrix factorization identified 13 gene expression modules linked to cell states or cell types that resemble differentiation states of normal intestinal epithelial cells.

To evaluate their presence in CRC patient tumors, the identified transcriptional programs were applied to publicly available expression data (TCGA cohort; n=459). Clustering of samples based on the contribution of individual expression signatures revealed six patient clusters with significantly different progression-free survival (p=0.043) and a trend towards different overall survival (p=0.12), indicating a relevance for patient outcome.

Comparing cell state meta-signature expression in cell type-associated subpopulations revealed differences in functional states, i.e. proliferative and metabolic activity. Interestingly, stem-like cells showed significantly increased oxidative phosphorylation (OXPHOS) and decreased glycolysis scores, suggesting a link between metabolic states and cell differentiation. scRNA-seq of patient-derived organoid and xenograft models as well as primary tumors revealed similar trends.

To assess whether metabolic states are linked to TIC activity, CRC spheroid cells were sorted according to mitochondrial membrane potential (MMP), and sphere forming cell (SFC) as well as TIC frequency were assessed by limiting dilutions. Strikingly, MMPhigh cells exhibited a pronounced increase of SFC frequencies in vitro compared to MMPlow cells in 80% of patients (n=5). In addition, TIC frequencies were strongly increased in the MMPhigh compared to the MMPlow subpopulation in vivo (n=2; 1/46,535 vs. 1/211,305 and 1/249 vs. 1/2,089), demonstrating that TIC activity relies on OXPHOS. In line with this, pretreatment with the OXPHOS inhibitor CCCP decreased SFC frequencies (n=3), indicating targetable metabolic vulnerability of CRC spheroid cells.

In summary, we here show that transcriptional heterogeneity identifies functional states during CRC TIC differentiation. Targeting context-dependent regulation of tumor cell differentiation might unravel novel vulnerabilities for therapeutic intervention in human CRC.

Citation Format: Martina K. Zowada, Stephan M. Tirier, Sebastian M. Dieter, Teresa Krieger, Ava Oberlack, Robert L. Chua, Mario Huerta, Foo Wei Ten, Karin Laaber, Jeongbin Park, Katharina Jechow, Torsten Müller, Mathias Kalxdorf, Mark Kriegsmann, Katharina Kriegsmann, Friederike Herbst, Jeroen Krijgsveld, Martin Schneider, Roland Eils, Hanno Glimm, Christian Conrad, Claudia R. Ball. Transcriptional heterogeneity identifies functional states of tumor-initiating cell differentiation in human colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1491.

A perivascular niche in the bone marrow hosts quiescent and proliferating tumorigenic colorectal cancer cells

Disseminated tumor cells (dTCs) can frequently be detected in the bone marrow (BM) of colorectal cancer (CRC) patients, raising the possibility that the BM serves as a reservoir for metastatic tumor cells. Identification of dTCs in BM aspirates harbors the potential of assessing therapeutic outcome and directing therapy intensity with limited risk and effort. Still, the functional and prognostic relevance of dTCs is not fully established. We have previously shown that CRC cell clones can be traced to the BM of mice carrying patient-derived xenografts. However, cellular interactions, proliferative state and tumorigenicity of dTCs remain largely unknown. Here, we applied a coculture system modeling the microvascular niche and used immunofluorescence imaging of the murine BM to show that primary CRC cells migrate toward endothelial tubes. dTCs in the BM were rare, but detectable in mice with xenografts from most patient samples (8/10) predominantly at perivascular sites. Comparable to primary tumors, a substantial fraction of proliferating dTCs was detected in the BM. However, most dTCs were found as isolated cells, indicating that dividing dTCs rather separate than aggregate to metastatic clones-a phenomenon frequently observed in the microvascular niche model. Clonal tracking identified subsets of self-renewing tumor-initiating cells in the BM that formed tumors out of BM transplants, including one subset that did not drive primary tumor growth. Our results indicate an important role of the perivascular BM niche for CRC cell dissemination and show that dTCs can be a potential source for tumor relapse and tumor heterogeneity.

The notch target gene HEYL modulates metastasis forming capacity of colorectal cancer patient-derived spheroid cells in vivo

BACKGROUND

While colorectal cancer (CRC) patients with localized disease have a favorable prognosis, the five-year-survival rate in patients with distant spread is still below 15%. Hence, a detailed understanding of the mechanisms regulating metastasis formation is essential to develop therapeutic strategies targeting metastasized CRC. The notch pathway has been shown to be involved in the metastatic spread of various tumor entities; however, the impact of its target gene HEYL remains unclear so far.

METHODS

In this study, we functionally assessed the association between high HEYL expression and metastasis formation in human CRC. Therefore, we lentivirally overexpressed HEYL in two human patient-derived CRC cultures differing in their spontaneous metastasizing capacity and analyzed metastasis formation as well as tumor cell dissemination into the bone marrow after xenotransplantation into NOD.Cg-Prkdc^scid Il2rg^tm1Wjl/SzJ (NSG) mice.

RESULTS

HEYL overexpression decreased tumor cell dissemination and the absolute numbers of formed metastases in a sub-renal capsular spontaneous metastasis formation model, addressing all steps of the metastatic cascade. In contrast, metastatic capacity was not decreased following intrasplenic xenotransplantation where the cells are placed directly into the blood circulation.

CONCLUSION

These results suggest that HEYL negatively regulates metastasis formation in vivo presumably by inhibiting intravasation of metastasis-initiating cells.

Mapping Active Gene-Regulatory Regions in Human Repopulating Long-Term HSCs

Genes that regulate hematopoietic stem cell (HSC) self-renewal, proliferation, and differentiation are tightly controlled by regulatory regions. However, mapping such regions relies on surface markers and immunophenotypic definition of HSCs. Here, we use γ-retroviral integration sites (γRV ISs) from a gene therapy trial for 10 patients with Wiskott-Aldrich syndrome to mark active enhancers and promoters in functionally defined long-term repopulating HSCs. Integration site clusters showed the highest ATAC-seq signals at HSC-specific peaks and strongly correlated with hematopoietic risk variants. Tagged genes were significantly enriched for HSC gene sets. We were able to map over 3,000 HSC regulatory regions in late-contributing HSCs, and we used these data to identify miR-10a and miR-335 as two miRNAs regulating early hematopoiesis. In this study, we show that viral insertion sites can be used as molecular tags to assess chromatin conformation on functionally defined cell populations, thereby providing a genome-wide resource for regulatory regions in human repopulating long-term HSCs.

Systematic Generation of Patient-Derived Tumor Models in Pancreatic Cancer

In highly aggressive malignancies like pancreatic cancer (PC), patient-derived tumor models can serve as disease-relevant models to understand disease-related biology as well as to guide clinical decision-making. In this study, we describe a two-step protocol allowing systematic establishment of patient-derived primary cultures from PC patient tumors. Initial xenotransplantation of surgically resected patient tumors (n = 134) into immunodeficient mice allows for efficient in vivo expansion of vital tumor cells and successful tumor expansion in 38% of patient tumors (51/134). Expansion xenografts closely recapitulate the histoarchitecture of their matching patients' primary tumors. Digestion of xenograft tumors and subsequent in vitro cultivation resulted in the successful generation of semi-adherent PC cultures of pure epithelial cell origin in 43.1% of the cases. The established primary cultures include diverse pathological types of PC: Pancreatic ductal adenocarcinoma (86.3%, 19/22), adenosquamous carcinoma (9.1%, 2/22) and ductal adenocarcinoma with oncocytic IPMN (4.5%, 1/22). We here provide a protocol to establish quality-controlled PC patient-derived primary cell cultures from heterogeneous PC patient tumors. In vitro preclinical models provide the basis for the identification and preclinical assessment of novel therapeutic opportunities targeting pancreatic cancer.

Succession of transiently active tumor-initiating cell clones in human pancreatic cancer xenografts

Although tumor-initiating cell (TIC) self-renewal has been postulated to be essential in progression and metastasis formation of human pancreatic adenocarcinoma (PDAC), clonal dynamics of TICs within PDAC tumors are yet unknown. Here, we show that long-term progression of PDAC in serial xenotransplantation is driven by a succession of transiently active TICs producing tumor cells in temporally restricted bursts. Clonal tracking of individual, genetically marked TICs revealed that individual tumors are generated by distinct sets of TICs with very little overlap between subsequent xenograft generations. An unexpected functional and phenotypic plasticity of pancreatic TICs in vivo underlies the recruitment of inactive TIC clones in serial xenografts. The observed clonal succession of TIC activity in serial xenotransplantation is in stark contrast to the continuous activity of limited numbers of self-renewing TICs within a fixed cellular hierarchy observed in other epithelial cancers and emphasizes the need to target TIC activation, rather than a fixed TIC population, in PDAC.

Effects of multifunctional cross-linkers on rheology and adhesion of soft nanostructured materials

We investigate the nanostructure, the rheology and the adhesion of soft supramolecular materials elaborated by blending monofunctional and multifunctional poly(isobutene) (PIB) chains. Monofunctional PIB chains (PIBUT) are linear and unentangled polymer chains (M_n ≈ 3 kg mol^-1) functionalized in the middle by a bis-urea interacting moiety, able to self-associate by four hydrogen bonds. Covalent coupling of monofunctional PIB allows us to synthesize longer chains bearing two or three interacting moieties. These chains are then added to monofunctional PIB to prepare blends containing up to 10% of multifunctional PIB (M-PIBUT). The influence of M-PIBUT on the supramolecular nanostructure, which results from the self-assembly of stickers, is studied by Atomic Force Microscopy and Small Angle X-ray Scattering at room temperature. Multifunctional and monofunctional chains are shown to interact with each other to form bundles of rod-like aggregates. The consequences of these interactions on the rheology of the blends were studied by shear tests in the linear and non linear regimes, below and above the order-disorder transition temperature. A pronounced strengthening effect of M-PIBUT is observed at room temperature: the supramolecular blends become more elastic and are more resistant to creep with increasing concentration of M-PIBUT. The effects of M-PIBUT on the nanostructure and the rheology suggest that M-PIBUT, which can link with more than one supramolecular aggregate, plays the role of a physical cross-linker. The impact of these supramolecular cross-linkers on the adhesion of the blends is studied by probe-tack tests and discussed by analyzing the in situ deformation through the debonding images.

Genetic subclone architecture of tumor clone-initiating cells in colorectal cancer

Combining high-coverage whole-genome sequencing with functional analyses, Giessler et al. demonstrate that tumor initiation and long-term tumor formation in human colorectal cancer are driven by multiple genomic subclones and that the functional heterogeneity of colorectal cancer tumor clone–initiating cells is not based on genomic architecture.

A hierarchically organized cell compartment drives colorectal cancer (CRC) progression. Genetic barcoding allows monitoring of the clonal output of tumorigenic cells without prospective isolation. In this study, we asked whether tumor clone-initiating cells (TcICs) were genetically heterogeneous and whether differences in self-renewal and activation reflected differential kinetics among individual subclones or functional hierarchies within subclones. Monitoring genomic subclone kinetics in three patient tumors and corresponding serial xenografts and spheroids by high-coverage whole-genome sequencing, clustering of genetic aberrations, subclone combinatorics, and mutational signature analysis revealed at least two to four genetic subclones per sample. Long-term growth in serial xenografts and spheroids was driven by multiple genomic subclones with profoundly differing growth dynamics and hence different quantitative contributions over time. Strikingly, genetic barcoding demonstrated stable functional heterogeneity of CRC TcICs during serial xenografting despite near-complete changes in genomic subclone contribution. This demonstrates that functional heterogeneity is, at least frequently, present within genomic subclones and independent of mutational subclone differences.

Increased DNA methylation of Dnmt3b targets impairs leukemogenesis

The de novo DNA methyltransferases Dnmt3a and Dnmt3b are of crucial importance in hematopoietic stem cells. Dnmt3b has recently been shown to play a role in genic methylation. To investigate how Dnmt3b-mediated DNA methylation affects leukemogenesis, we analyzed leukemia development under conditions of high and physiological methylation levels in a tetracycline-inducible knock-in mouse model. High expression of Dnmt3b slowed leukemia development in serial transplantations and impaired leukemia stem cell (LSC) function. Forced Dnmt3b expression induced widespread DNA hypermethylation inMyc-Bcl2-induced leukemias, preferentially at gene bodies.MLL-AF9-induced leukemogenesis showed much less pronounced DNA hypermethylation upon Dnmt3b expression. Nonetheless, leukemogenesis was delayed in both models with a shared core set of DNA hypermethylated regions and suppression of stem cell-related genes. Acute myeloid leukemia patients with high expression of Dnmt3b target genes showed inferior survival. Together, these findings indicate a critical role for Dnmt3b-mediated DNA methylation in leukemia development and maintenance of LSC function.

Phenotypic differentiation does not affect tumorigenicity of primary human colon cancer initiating cells

Within primary colorectal cancer (CRC) a subfraction of all tumor-initiating cells (TIC) drives long-term progression in serial xenotransplantation. It has been postulated that efficient maintenance of TIC activity in vitro requires serum-free spheroid culture conditions that support a stem-like state of CRC cells. To address whether tumorigenicity is indeed tightly linked to such a stem-like state in spheroids, we transferred TIC-enriched spheroid cultures to serum-containing adherent conditions that should favor their differentiation. Under these conditions, primary CRC cells did no longer grow as spheroids but formed an adherent cell layer, up-regulated colon epithelial differentiation markers, and down-regulated TIC-associated markers. Strikingly, upon xenotransplantation cells cultured under either condition equally efficient formed serially transplantable tumors. Clonal analyses of individual lentivirally marked TIC clones cultured under either culture condition revealed no systematic differences in contributing clone numbers, indicating that phenotypic differentiation does not select for few individual clones adapted to unfavorable culture conditions. Our results reveal that CRC TIC can be propagated under conditions previously thought to induce their elimination. This phenotypic plasticity allows addressing primary human CRC TIC properties in experimental settings based on adherent cell growth.

The tRNA methyltransferase Dnmt2 is required for accurate polypeptide synthesis during haematopoiesis

The Dnmt2 enzyme utilizes the catalytic mechanism of eukaryotic DNA methyltransferases to methylate several tRNAs at cytosine 38. Dnmt2 mutant mice, flies, and plants were reported to be viable and fertile, and the biological function of Dnmt2 has remained elusive. Here, we show that endochondral ossification is delayed in newborn Dnmt2-deficient mice, which is accompanied by a reduction of the haematopoietic stem and progenitor cell population and a cell-autonomous defect in their differentiation. RNA bisulfite sequencing revealed that Dnmt2 methylates C38 of tRNA Asp^GTC, Gly^GCC, and Val^AAC, thus preventing tRNA fragmentation. Proteomic analyses from primary bone marrow cells uncovered systematic differences in protein expression that are due to specific codon mistranslation by tRNAs lacking Dnmt2-dependent methylation. Our observations demonstrate that Dnmt2 plays an important role in haematopoiesis and define a novel function of C38 tRNA methylation in the discrimination of near-cognate codons, thereby ensuring accurate polypeptide synthesis.

COMPRES: a prospective postmarketing evaluation of the compression anastomosis ring CAR 27(™) /ColonRing(™)

AIM

Preclinical studies have suggested that nitinol-based compression anastomosis might be a viable solution to anastomotic leak following low anterior resection. A prospective multicentre open label study was therefore designed to evaluate the performance of the ColonRing(™) in (low) colorectal anastomosis.

METHOD

The primary outcome measure was anastomotic leakage. Patients were recruited at 13 different colorectal surgical units in Europe, the United States and Israel. Institutional review board approval was obtained.

RESULTS

Between 21 March 2010 and 3 August 2011, 266 patients completed the study protocol. The overall anastomotic leakage rate was 5.3% for all anastomoses, including a rate of 3.1% for low anastomoses. Septic anastomotic complications occurred in 8.3% of all anastomoses and 8.2% of low anastomoses.

CONCLUSION

Nitinol compression anastomosis is safe, effective and easy to use and may offer an advantage for low colorectal anastomosis. A prospective randomized trial comparing ColonRing(™) with conventional stapling is needed.

Polyol synthesis of non-stoichiometric Mn–Zn ferrite nanocrystals: structural /microstructural characterization and catalytic application

The structure and microstructure of polyol-made non-stoichiometric Mn–Zn ferrite nanoparticles were successfully investigated and correlated to their catalytic properties toward dimethyl ether oxidation reaction.

Induction of the proapoptotic tumor suppressor gene Cell Adhesion Molecule 1 by chemotherapeutic agents is repressed in therapy resistant acute myeloid leukemia

Even though a large proportion of patients with acute myeloid leukemia (AML) achieve a complete remission upon initial therapy, the majority of them eventually relapse with resistant disease. Overexpression of the gene coding for the transcription factor Ecotropic Virus Integration site 1 (EVI1) is associated with rapid disease recurrence and shortened survival. We therefore sought to identify EVI1 target genes that may play a role in chemotherapy resistance using a previously established in vitro model system for EVI1 positive myeloid malignancies. Gene expression microarray analyses uncovered the Cell Adhesion Molecule 1 (CADM1) gene as a candidate whose deregulation by EVI1 may contribute to drug refractoriness. CADM1 is an apoptosis inducing tumor suppressor gene that is inactivated by methylation in a variety of tumor types. In the present study we provide evidence that it may play a role in chemotherapy induced cell death in AML: CADM1 was induced by drugs used in the treatment of AML in a human myeloid cell line and in primary diagnostic AML samples, and its experimental expression in a cell line model increased the proportion of apoptotic cells. CADM1 up-regulation was abolished by ectopic expression of EVI1, and EVI1 expression correlated with increased CADM1 promoter methylation both in a cell line model and in primary AML cells. Finally, CADM1 induction was repressed in primary samples from AML patients at relapse. In summary, these data suggest that failure to up-regulate CADM1 in response to chemotherapeutic drugs may contribute to therapy resistance in AML.

Diagnosis, management and outcome of early anastomotic leakage following colorectal anastomosis using a compression device: is it different?

AIM

Compression anastomosis has proved to be safe for rectal reconstruction with leak rates comparable to those observed using circular stapling devices. However, there are no data on whether the metallic compression ring alters the ease of diagnosis or the treatment in cases of leakage. In this study, we present our experience with early leakage following compression anastomosis.

METHOD

A prospective registry was used for data review. Patients with anastomotic leakage following compression anastomosis between November 2008 and September 2013 were included.

RESULTS

In all, 197 (92 female) patients were operated using a novel compression device. Early leakage was found in 10 (5.1%) patients after a median of 5 (3-14) days. The radiologist was able to detect leakage using CT in nine out of 10 cases unequivocally. Removal of the ring was necessary in eight of the 10 cases, and salvage of the anastomosis was feasible on six occasions. In all diverted cases with a low anastomosis, a transanal repair of the defect was feasible in three cases, including a single patient with complete separation of the anastomosis.

CONCLUSION

Artefacts on the CT scan caused by the compression ring did not hamper the diagnosis of anastomotic leakage. Removal of the ring in the early postoperative period is not associated with complete separation of the bowel ends. Salvage of anastomosis is feasible in most cases.

Surgical recurrence after primary ileocolic resection for Crohn's disease

BACKGROUND

The current study was conducted to assess long-term outcomes after primary ileocolic resection for Crohn's disease (CD) and to identify factors associated with surgical relapse in the era of immunosuppressive medications.

METHODS

Data were collected retrospectively on 116 consecutive patients, who underwent primary ileocolic resection for CD at a tertiary referral center between 1997 and 2006. Medical records were reviewed, and the use of immunomodulators was noted. The cumulative probability for a second operation due to recurrent CD was described by Kaplan-Meier curves.

RESULTS

Ten patients (8.6 %) developed surgical recurrence after a mean follow-up period of 8.1 (±2.6) years. The percentage of patients not requiring further surgery was 96.5% and 88.0 % at 5 and 10 years, respectively. An urgent indication for surgery was significantly associated with the necessity of repeated intestinal resection (hazard ratio 5.6, 95 % confidence interval 1.2-27.0, p = 0.0145). In addition, postoperative exposure to azathioprine/6-mercaptopurine for more than 3 months decreased the probability of surgical recurrence significantly (hazard ratio 2.5, 95 % confidence interval 0.6-9.9, p = 0.0349).

CONCLUSIONS

In contrast to previous studies, we observed a significant low surgical recurrence rate after primary ileocolic resection. Additionally, maintenance treatment with azathioprine/6-mercaptopurine after surgery may reduce the necessity for repeat surgical intervention.

EVI1 inhibits apoptosis induced by antileukemic drugs via upregulation of CDKN1A/p21/WAF in human myeloid cells

Overexpression of ecotropic viral integration site 1 (EVI1) is associated with aggressive disease in acute myeloid leukemia (AML). Despite of its clinical importance, little is known about the mechanism through which EVI1 confers resistance to antileukemic drugs. Here, we show that a human myeloid cell line constitutively overexpressing EVI1 after infection with a retroviral vector (U937_EVI1) was partially resistant to etoposide and daunorubicin as compared to empty vector infected control cells (U937_vec). Similarly, inducible expression of EVI1 in HL-60 cells decreased their sensitivity to daunorubicin. Gene expression microarray analyses of U937_EVI1 and U937_vec cells cultured in the absence or presence of etoposide showed that 77 and 419 genes were regulated by EVI1 and etoposide, respectively. Notably, mRNA levels of 26 of these genes were altered by both stimuli, indicating that EVI1 regulated genes were strongly enriched among etoposide regulated genes and vice versa. One of the genes that were induced by both EVI1 and etoposide was CDKN1A/p21/WAF, which in addition to its function as a cell cycle regulator plays an important role in conferring chemotherapy resistance in various tumor types. Indeed, overexpression of CDKN1A in U937 cells mimicked the phenotype of EVI1 overexpression, similarly conferring partial resistance to antileukemic drugs.

Repeat endorectal advancement flap after flap breakdown and recurrence of fistula-in-ano--is it an option?

AIM

Endorectal advancement flaps are an established treatment for high transsphincteric and suprasphincteric fistulae. The outcome of a repeat procedure in the case of flap breakdown and fistula recurrence remains unclear. The aim of the study was to analyse the outcome of repeat endorectal advancement flaps.

METHODS

We retrospectively analysed patients with a repeat endorectal advancement flap procedure after flap breakdown and recurrence of fistula-in-ano of cryptoglandular origin who had been treated in our unit between 1994 and 2010.

RESULTS

In all, 97 patients underwent an endorectal advancement flap procedure for fistula-in-ano and, of these, nine patients (five men, four women, 9.3%) subsequently underwent a repeat procedure due to flap breakdown. Median age was 40 years (range 25-60). Median follow-up time was 85 months (range 26-136). Seven full-thickness and two mucosal flap repeat procedures were performed because of eight transsphincteric and one suprasphincteric fistulae. The repeat procedure was successful in seven (78%) patients. In one of the two patients with repeat flap failure, a third flap procedure failed again. Disturbances of postoperative faecal incontinence were observed in five (55%) patients. Overall, the median postoperative Vaizey faecal incontinence score was 1 (range 0-4).

CONCLUSION

Repeat endorectal advancement flap procedures are feasible and associated with a low recurrence rate and mild postoperative faecal incontinence. Therefore, a repeat procedure is a viable option in the case of a flap breakdown and fistula recurrence.

Overexpression of EVI1 interferes with cytokinesis and leads to accumulation of cells with supernumerary centrosomes in G0/1 phase

Ectopic viral integration site 1 (EVI1), a transcription factor frequently overexpressed in myeloid neoplasias, has been implicated in the generation of malignancy-associated centrosomal aberrations and chromosomal instability. Here, we sought to investigate the underlying cause of centrosome amplification in EVI1-overexpressing cells. We found that overexpression of EVI1-HA in U2OS cells induced supernumerary centrosomes, which were consistently associated with enlarged nuclei or binuclear cells. Live cell imaging experiments identified cytokinesis failure as the underlying cause of this phenotype. In accordance with previous reports, EVI1 overexpression induced a partial cell cycle arrest in G0/1 phase, accompanied by elevated cyclin D1 and p21 levels, reduced Cdk2 activity and activation of the p53 pathway. Supernumerary centrosomes predominantly occurred in resting cells, as identified by low levels of the proliferation marker Ki-67, leading to the conclusion that they result from tetraploidization after cytokinesis failure and are confined to G0/1-arrested tetraploid cells. Depletion of p53 using siRNA revealed that further polyploidization of these cells was inhibited by the p53-dependent tetraploidy checkpoint.

P5-22-01: Feasibility and Patient Safety of Serial Biopsies (bx) in Metastatic HER2−Positive Breast Cancer (BC) To Evaluate Alterations in Molecular Biomarkers (BM): Preliminary Results of SHERsig (Study of HER2 Signature in Metastatic Breast Cancer) a Prospective Phase II Study

Background

The use of trastuzumab (H)-based therapy for HER2−positive BC has significantly altered outcomes. Yet up to 64% of metastatic patients (pts) fail to respond (Robert JCO 2006) and most pts will progress within 24–42 months (m) following an initial response for metastatic disease. Preclinical data suggest several in vitro resistance mechanisms but confirmatory in vivo data are lacking, preventing optimal personalized care. This ongoing proof-of-concept study examines serial bx in pts with HER2−positive metastatic BC in order to assess BM profiles across multiple lines of treatment.

Methods: Key eligibility criteria include: centrally confirmed HER2 status, minimum of 1 disease site considered suitable for serial bx, normal coagulation profile and cardiac function, prior adjuvant/neoadjuvant taxane and H completed ≥12 m and ≥6 m respectively, ECOG ≤2. Pts receive q3wk H with clinician choice of taxane (docetaxel 75–100 mg/m2 q21, paclitaxel 80 mg/m2 weekly or 175 mg/m2 q21 [TH]). At the time of progressive disease, pts receive capecitabine (X) and H. Two core bx and 1 optional fine needle aspirate are performed at the following times: baseline (after 3 weeks [w] of TH), at 6 w, at time of first progression prior to XH, and at the time of progression on XH. Tumor assessments are performed at 6 w, then 9 w intervals, with cardiac assessment every 6 m. Primary endpoint aims to explore and potentially define BM signatures that could alter during HER2−targeted therapy and predict for decreased or increased sensitivity to H-based treatment. Secondary endpoints include bx safety, ORR and TTP. At time of baseline bx, pts have the option to complete a pt satisfaction questionnaire.

Results: Between August 2009 and June 2011, 58 pts were screened; 29 enrolled. The other 29 pts were screen failures, with 3 pts (5%) specifically declining entry due to the requirement for serial bx. Median age is 53 y (range 37–86), with 9 and 20 pts having recurrent or de novo metastatic disease. Eight pts received adjuvant systemic treatment, including H in 4 pts. Baseline bx performed in the breast, n (%): 15 (52), bone: 6 (21), liver: 4 (14), and lymph nodes: 4 (14); 14 and 27 pts underwent bx at 3 and 6 w respectively. After a median of 34 w of treatment 11 pts progressed on TH and 7 pts underwent planned bx. There were 12 SAEs, none related to bx. Most AEs were grade 1/2 (95%) with 3% grade 3 and 1 death due to intercurrent illness. From a total of 43 bx, 12 (27%) grade 1/2 AEs (hematoma 2, transient hypotension 2, mild pain 8) were reported, with resolution in all instances. Fifteen pts consented to the pt satisfaction substudy.

Conclusions: Preliminary results of the first reported serial bx study in metastatic BC demonstrated 95% pt acceptance of this approach. Evaluation of BM profiles will be conducted following planned recruitment of 50 pts. To date, the feasibility and safety of obtaining serial bx in metastatic BC is supported by the current safety profile and patient uptake. Updated recruitment data will be presented.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-22-01.

Bridging the gap with an ileocolonic graft after extensive colorectal resections

BACKGROUND

Ileocecal interposition (ICI) for first-line reconstruction after low anterior colorectal resection was introduced by von Flüe and Harder in 1994 (Dis Colon Rectum 37:1160-1162, 1994). We report our experience using this technique to bridge colonic gaps after significant loss of bowel length.

PATIENTS AND METHODS

Between 1999 and 2009 the left-sided colon was too short for traditional isoperistaltic reconstruction in six patients treated in our hospital. Reasons for extensive bowel loss were a deficient (n = 3) or torn (n = 1) marginal artery with ischemia or repeat colorectal resections (n = 2). An ICI was done to bridge the gap and enable restoration of intestinal continuity.

RESULTS

No patient died. Whenever performing a coloanal anastomosis (4/6) a loop ileostomy was raised. One patient with colonic diversion experienced graft-related complications: ischemic colitis of the interposed colonic segment, anastomotic stenosis, and a presacral sinus were observed and managed nonoperatively. Subsequent closure of the stoma was possible in all cases. A median Vaizey incontinence score of 9 (range: 4-14) was recorded in the patient with coloanal anastomosis. The average number of bowel movements per day was 1.5 (range: 0.5-6).

CONCLUSIONS

When the descending colon does not reach the rectal stump or anal canal in reoperative cases or after vascular complication, ICI is a useful salvage procedure resulting in good bowel function.

Treatment of perianal sepsis and long-term outcome of recurrence and continence

AIM

The study investigated the fate of patients with perianal sepsis of cryptoglandular origin.

METHOD

All patients treated for perianal sepsis between January 1994 and December 2000 were retrospectively analysed regarding recurrence and faecal incontinence. Data collection was conducted by chart review and by telephone questionnaire using the Vaizey incontinence score.

RESULTS

One hundred seventy-three (58%) of 300 patients were available for follow-up at a median period of 121 (77-171) months. Fistula-in-ano was diagnosed in 156 (90%) patients. After a single surgical procedure, 55 (32%) patients had no recurrence of perianal sepsis. In 118 (68%), recurrence required multiple procedures (median 3, range 2-19). If only a single incision and drainage was performed (n = 10, 6%), no faecal incontinence occurred. Drainage with fistulotomy (n = 45, 26%) induced mild incontinence in 9% and severe incontinence in 4%. After multiple procedures that were required in 118 (68%) patients, mild and severe faecal incontinence was found in 16% and 4% of them, respectively.

CONCLUSION

Treatment of anal sepsis is associated with a high recurrence rate and a substantial risk of faecal incontinence.

Short-term complications of wide-lumen stapled anastomosis after ileocolic resection for Crohn's disease: who is at risk?

AIM

There is growing evidence that stapled anastomoses are similarly effective compared to hand-sewn anastomoses in Crohn's patients. This study was designed to assess safety and limitations of wide-lumen stapled ileocolic anastomoses.

METHOD

All patients with ileocolic resections for Crohn's disease perfomed between 1998 and 2006 were studied. A stapled anastomosis was constructed whenever possible. Potential risk factors for postoperative complications were recorded, retrospectively. Univariate and multivariate analyses were performed.

RESULTS

In 209 out of 220 cases (95%, 132 primary operations) stapled anastomoses were performed. Eleven patients underwent a hand-sewn anastomosis owing to massive bowel dilatation (n = 7) or increased wall thickness (n = 4). There were 10 major (4.5%; surgical: 8, medical: 2) complications including two anastomotic leaks and one anastomotic bleed (all from stapled anastomoses) and one death not related to the anastomosis. Minor complications occurred in 25 patients. In multivariate analysis, major surgical postoperative complications were significantly associated with a low level of albumin (P = 0.0113) and previous resections for Crohn's disease (P = 0.0144).

CONCLUSION

Stapled ileocolic anastomosis was safe in the majority of Crohn's patients. The most important limitation was technical impracticability. A low level of albumin and a history of previous resection increased the risk of postoperative complications.

Postoperative course and long term follow up after colectomy for slow transit constipation--is surgery an appropriate approach?

OBJECTIVE

Patients with slow transit constipation who do not respond satisfactorily to common medical treatment are considered candidates for colectomy. The present observational long term study was designed to assess outcome after surgery.

METHOD

Twenty consecutive patients were treated by colectomy for slow transit constipation between 1996 and 2004. Preoperative and postoperative data were reviewed by using our institutional database. A questionnaire including validated scoring systems and questions about complications and subsequent surgical interventions was sent to all available patients.

RESULTS

Three patients (15%) died perioperatively. Median long term follow up was 84 months. Ten patients (50%) needed further operations after colectomy: Three patients (15%) had surgery during the early postoperative period, seven patients (35%) during follow up. A total of 31 operations had to be performed in these patients. Twelve patients (86%) responded to the questionnaires. Their median Wexner constipation score was 11.5 (range 8-23). Six patients fulfilled the Rome II criteria for constipation. The median Vaizey incontinence score was 7.5 (range 0-22). The median GIQLI showed 80 points (range 32-129).

CONCLUSION

Morbidity and mortality rate after colectomy were inadmissibly high. Taking into account the poor functional results, we cannot recommend colectomy for slow transit constipation.

A prospective randomised phase III trial of adjuvant chemotherapy with 5-fluorouracil and leucovorin in patients with stage II colon cancer

The purpose of this trial was to investigate the efficacy of adjuvant chemotherapy with 5-fluorouracil (5-FU) and leucovorin (LV) in stage II colon cancer. Patients with stage II colon cancer were randomised to either adjuvant chemotherapy with 5-FU/LV (100 mg m⁻² LV+450 mg m⁻² 5-FU weekly, weeks 1–6, in 8 weeks cycles × 7) or surveillance only. Five hundred patients were evaluable for analyses. After a median follow-up of 95.6 months, 55 of 252 patients (21.8%) have died in the 5-FU/LV arm and 58 of 248 patients (23.4%) in the surveillance arm. There was no statistically significant difference in overall survival (OS) between the two treatment arms (hazard ratios, HR 0.88, 95% CI 0.61–1.27, P=0.49). The relative risk for tumour relapse was higher for patients on the surveillance arm than for those on the 5-FU/LV arm; however, this difference was not statistically significant (HR 0.69, 95% CI 0.45–1.06, P=0.09). Consequently, disease-free survival (DFS) was not significantly different between the two trial arms. In conclusion, results of this trial demonstrate a trend to a lower risk for relapse in patients treated with adjuvant 5-FU/LV for stage II colon cancer. However, in this study with limited power to detect small differences between the study arms, adjuvant chemotherapy failed to significantly improve DFS and OS.

Straight and colonic J-pouch reconstruction after low anterior resection

PURPOSE

A complication after restorative rectal surgery with a straight anastomosis is low-anterior resection syndrome with a postoperatively deteriorated anorectal function. The colonic J-reservoir is sometimes used with the purpose of reducing these symptoms. An alternative method is to use a simple side-to-end anastomosis or a coloplasty.

MATERIAL AND METHODS

Three-hundred fiftyseven patients with rectal cancer undergoing total mesorectal excision (TME). Three-hundred (84.0%) received a low anterior resection with primary anastomosis and colo-rectal n = 194 (64.6%) or colo-anal anastomosis n = 106 (35.3%). A colonic pouch using the descending colon was created in 24 patients and in 75 patients respectively. Surgical results and complications were recorded. Patients were followed with a functional evaluation at 6 and 12 months postoperatively.

RESULTS

Patient characteristics in both groups were very similar regarding gender, age, tumor level, and Dukes' stages. A large proportion of the patients received short-term preoperative radiotherapy (72%). There was no significant difference in surgical outcome between the 2 techniques with respect to anastomotic height, perioperative blood loss, postoperative complications, reoperations, hospital stay or pelvic sepsis rates except the anastomotic stricture rate in the colonic J-Pouch group after coloanal anastomosis (p < 0.02).

CONCLUSIONS

These data show that either a colonic J-pouch or a straight anastomosis performed on the descending colon in low-anterior resection with TME are methods that can be used with similar expected surgical and functional results.

Laparoscopic surgery impairs tissue oxygen tension more than open surgery

Background

Wound infection remains a common and serious complication after colonic surgery. Although many colonic operations are performed laparoscopically, it remains unclear whether this has any impact on the incidence of wound infection. Subcutaneous tissue oxygenation is an excellent predictor of surgical wound infection. The impact of open and laparoscopic colonic surgery on tissue oxygenation was compared.

Methods

Fifty-two patients undergoing elective open and laparoscopic left-sided colonic resections were evaluated in a prospective observational study. Anaesthesia management was standardized and intraoperative arterial partial pressure of oxygen was kept at 150 mmHg in both groups. Oxygen tension was measured in the subcutaneous tissue of the right upper arm.

Results

At the start of surgery subcutaneous tissue oxygen tension (Psqo2) was similar in both groups (mean(s.d.) 65·8(17·2) and 63·7(23·6) mmHg for open and laparoscopic operations respectively; P = 0·714). Tissue oxygen remained stable in the open group, but dropped significantly in the laparoscopic group during the course of surgery (Psqo2 after operation 53·4(12·9) and 45·5(11·6) mmHg, respectively; P = 0·012).

Conclusion

Laparoscopic colonic surgery significantly decreases Psqo2, an effect that occurs early in the course of surgery. As tissue oxygen tension is a predictor of wound infection, these results may explain why the risk of wound infection after laparoscopic surgery remains higher than expected.

Molecular risk estimation and adjuvant chemotherapy in node-negative breast cancer patients—A status report of the prospective clinical trial NNBC 3-Europe

10503

Background: Feasibility of risk assessment in node negative breast cancer using the invasion markers urokinase-type plasminogen activator uPA and its inhibitor PAI-1 has been demonstrated in several prospective and retrospective studies and in a large meta analysis. Patients with low uPA and/or PAI-1 concentrations in tumor tissue levels have an excellent 5-year overall survival (>95%) even without any adjuvant therapy. Use of these molecular markers may spare adjuvant chemotherapy in approximately one half of node-negative breast cancer patients. Particulary, patients with an intermediate grade tumor can easily be differentiated in low and high risk. In addition, patients with high uPA and/or PAI-1 level seem to benefit from adjuvant chemotherapy. The NNBC-3-Europe trial seeks to answer two questions: 1. Is risk assessment by molecular markers uPA/PAI-1 superior to that by clinico-pathological factors regarding identification of low-risk patients? 2. Is adjuvant chemotherapy with anthracycline-taxane sequence (FEC-Docetaxel) superior to standard FEC in high-risk patients? Methods: In the NNBC-3-Europe trial, participating centres opt to either perform risk estimation by clinico-pathological factors or by the uPA and PAI-1 concentration in tumor tissue biopsies. Low-risk patients will be observed without adjuvant chemotherapy. High-risk patients are randomised based on the kind of adjuvant chemotherapy. Patients with steroid hormone receptor positive tumors receive adequate endocrine therapy. Results: Of the first 506 patients in the study arm with molecular risk assessment, 62 had a grade 1 tumors, and 184 had grade 3 tumors. Among grade 2 tumors (n = 260), 87 had low uPA/PAI-1. 173 patients presented with high levels. About 30% of the patients were allocated to the low-risk group using uPA/PAI-1. Conclusions: An adjuvant chemotherapy trial based on uPA/PAI-1 determination in the primary tumor is feasible in a multicentre setting. Applying these molecular markers for risk assessment, at this stage of the study, adjuvant chemotherapy could be spared in almost one third of N0 patients. It is performed in association with the EORTC PathoBiology Group Receptor und the German AGO Breast Group.

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