Tumour-stroma ratio to predict pathological response to neo-adjuvant treatment in rectal cancer.

INTRODUCTION: Management of rectal cancer has advanced, with an increasing use of neoadjuvant chemoradiotherapy (nCRT). This opens options for organ preserving treatment for those with a major response to nCRT. However, the degree of clinical response, based on MRI and post-treatment biopsies, only poorly matches the degree of actual pathological response. In order to select patients with major pathological response without surgical resection, it is of importance to define tumour markers predicting the degree of pathological response to nCRT. The intra-tumoural tumour-stroma ratio (TSR) might be this marker. METHODS: TSR in pre-treatment biopsies was estimated according to the method described by van Pelt et al. The degree of pathological response was assessed on the tumour resection according to tumour regression grading (TRG) by Mandard. The primary endpoint of this study was the difference in pathological response to nCRT between TSR-high and TSR-low groups. RESULTS: We found that 26.2% of patients with major response was classified as TSR-high, while 73.8% of patients were classified as TSR-low. A high TSR in pre-treatment biopsies was associated with a lower chance of major-response to nCRT (OR = 0.37, 95%CI; 0.19-0.73), p = 0.004), independent of tumour stage and time between nCRT and surgery. CONCLUSION: In rectal cancer, TSR in pre-treatment biopsies predicts pathologic response to nCRT, with a high TSR bringing twice the risk of poor to no response compared to low TSR. In future, assessment of TSR may fulfil a role in a therapeutic algorithm identifying patients who will or will not respond to nCRT prior to treatment initiation.

A high tumour-stroma ratio (TSR) in colon tumours and its metastatic lymph nodes predicts poor cancer-free survival and chemo resistance.

PURPOSE: Despite known high-risk features, accurate identification of patients at high risk of cancer recurrence in colon cancer remains a challenge. As tumour stroma plays an important role in tumour invasion and metastasis, the easy, low-cost and highly reproducible tumour-stroma ratio (TSR) could be a valuable prognostic marker, which is also believed to predict chemo resistance. METHODS: Two independent series of patients with colon cancer were selected. TSR was estimated by microscopic analysis of 4 µm haematoxylin and eosin (H&E) stained tissue sections of the primary tumour and the corresponding metastatic lymph nodes. Patients were categorized as TSR-low (≤ 50%) or TSR-high (> 50%). Differences in overall survival and cancer-free survival were analysed by Kaplan-Meier curves and cox-regression analyses. Analyses were conducted for TNM-stage I-II, TNM-stage III and patients with an indication for chemotherapy separately. RESULTS: We found that high TSR was associated with poor cancer-free survival in TNM-stage I-II colon cancer in two independent series, independent of other known high-risk features. This association was also found in TNM-stage III tumours, with an additional prognostic value of TSR in lymph node metastasis to TSR in the primary tumour alone. In addition, high TSR was found to predict chemo resistance in patients receiving adjuvant chemotherapy after surgical resection of a TNM-stage II-III colon tumour. CONCLUSION: In colon cancer, the TSR of both primary tumour and lymph node metastasis adds significant prognostic value to current pathologic and clinical features used for the identification of patients at high risk of cancer recurrence, and also predicts chemo resistance.

The difference in local, regional and distant breast cancer recurrence between the immediate and delayed DIEP flap procedure; a retrospective cohort study.

PURPOSE: It has been hypothesized that autologous breast reconstruction can cause reactivation of dormant micro metastases by its extensive tissue trauma, influencing the risk of breast cancer recurrence. However, about the specific effect of timing on breast cancer recurrence in the deep inferior epigastric perforator (DIEP) flap reconstruction is not much known. In this study the rate of local, regional and distant recurrence between patients undergoing an immediate and delayed autologous DIEP flap breast reconstruction were evaluated. METHODS: In this retrospective cohort study, breast cancer patients undergoing a DIEP flap breast reconstruction between 2010 and 2018 in three hospitals in the Netherlands were evaluated. Cox proportional hazards regression analyses were performed to assess the impact of different factors on breast cancer recurrence. The primary endpoint was local breast cancer recurrence. Secondary endpoints were regional and distant recurrence. RESULTS: A total of 919 DIEP-flap reconstructions were done in 862 women of which 347 were immediate- and 572 were delayed DIEP flap reconstructions. After a median follow-up of 46 months and 86 months respectively (p < 0.001), local breast cancer recurrence occurred in 1.5% and in 1.7% of the patients resulting in an adjusted hazard ratio of 2.890 (p = 0.001, 95% CI 1.536, 5437). CONCLUSION: This study suggests an increased risk for breast cancer recurrence in women receiving a delayed DIEP flap reconstruction as compared to women receiving an immediate DIEP flap reconstruction. However, these data should be interpreted carefully as a result of selection bias.

A novel classification of colorectal tumors based on microsatellite instability, the CpG island methylator phenotype and chromosomal instability: implications for prognosis.

BACKGROUND: We studied the overlap between the major (epi)genomic events microsatellite instability (MSI), the CpG island methylator phenotype (CIMP) and chromosomal instability (CIN) in colorectal cancer (CRC), and whether specific (epi)genotypes were associated with CRC-related deaths. PATIENTS AND METHODS: Molecular analyses using tumor DNA were successful in 509 CRC cases identified within the Netherlands Cohort Study in the period 1989-1993. Follow-up for the vital status until May 2005 was 100%. RESULTS: MSI (12.6%), CIMP-only (5.3%), CIMP + CIN (13.4%), CIN-only (58.2%) and triple-negative tumors (10.6%) differed significantly regarding tumor localization, differentiation grade, initial adjuvant therapy (AT) use and genetic characteristics (P ≤ 0.03). CIMP-only, CIMP + CIN and triple-negative tumors, compared with CIN-only tumors, were significantly associated with a 3.67, 2.44 and 3.78-fold risk of CRC-related deaths after 2-year follow-up (95% confidence intervals, CIs, 1.70-7.91, 1.35-4.41 and 1.97-7.25, respectively), but not after late follow-up. MSI tumors were borderline significantly associated with a 0.40-fold risk of CRC-related deaths after late follow-up (95% CI 0.15-1.03). CONCLUSION(S): This is the first study to show that specific (epi)genotypes may hold a differential prognostic value that may vary over time. Although no specific treatment data were available, an explanation for the differential findings over time might be that (epi)genotypes modify therapy response.

Endoscopic red flags for the detection of high-risk serrated polyps: an observational study.

BACKGROUND AND STUDY AIMS: In routine practice, colonoscopy may fail to prevent colorectal cancer (CRC), especially in the proximal colon. A better endoscopic recognition of serrated polyps is important, as this pathway may explain some of the post-colonoscopy cancers. In this study, the endoscopic characteristics of serrated polyps were examined. PATIENT AND METHODS: This was a cross-sectional, single-center study of all consecutive patients referred for elective colonoscopy during 1 year. The endoscopists were familiarized with the detection and treatment of nonpolypoid colorectal lesions. Serrated polyps were classified into high risk serrated polyps, defined as dysplastic or large (≥ 6 mm) proximal nondysplastic serrated polyps, and low risk serrated polyps including the remaining nondysplastic serrated polyps. Advanced colorectal neoplasms were defined as multiple (at least three),≥ 10 mm in size, high grade dysplastic adenomas or CRC. RESULTS: A total of 2309 patients were included (46.1 % men, mean age 58.4 years), of whom 2.5 % (57) had at least one high risk serrated polyp and 13.9 % (322) had at least one advanced neoplasm. Overall, serrated polyps were more often nonpolypoid than adenomas (16.2 % vs. 11.1 %; P = 0.002). In total, 65 high risk serrated polyps were found, of which 43.1 % (28) displayed a nonpolypoid endoscopic appearance. Patients with advanced neoplasms were more likely to have synchronous high risk serrated polyps than patients without advanced neoplasms: OR 3.66 (95 % CI 2.03 - 6.61, P < 0.001). CONCLUSIONS: High risk serrated polyps are frequently nonpolypoid and are associated with synchronous advanced colorectal neoplasms. Advanced colorectal neoplasms may therefore be considered red flags for the presence of high risk serrated polyps. Detection, diagnosis, and treatment of high risk serrated lesions may be important targets to improve the quality of colonoscopic cancer prevention.

MGMT and MLH1 promoter methylation versus APC, KRAS and BRAF gene mutations in colorectal cancer: indications for distinct pathways and sequence of events.

BACKGROUND: To study how caretaker gene silencing relates to gatekeeper mutations in colorectal cancer (CRC), we investigated whether O6-methylguanine DNA methyltransferase (MGMT) and Human Mut-L Homologue 1 (MLH1) promoter hypermethylation are associated with APC, KRAS and BRAF mutations among 734 CRC patients. METHODS: We compared MGMT hypermethylation with G:C > A:T mutations in APC and KRAS and with the occurrence of such mutations in CpG or non-CpG dinucleotides in APC. We also compared MLH1 hypermethylation with truncating APC mutations and activating KRAS and BRAF mutations. RESULTS: Only 10% of the tumors showed both MGMT and MLH1 hypermethylation. MGMT hypermethylation occurred more frequently in tumors with G:C > A:T KRAS mutations (55%) compared with those without these mutations (38%, P < 0.001). No such difference was observed for G:C > A:T mutations in APC, regardless of whether mutations occurred in CpG or non-CpG dinucleotides. MLH1 hypermethylation was less common in tumors with APC mutations (P = 0.006) or KRAS mutations (P = 0.001), but was positively associated with BRAF mutations (P < 0.001). CONCLUSIONS: MGMT hypermethylation is associated with G:C > A:T mutations in KRAS, but not in APC, suggesting that MGMT hypermethylation may succeed APC mutations but precedes KRAS mutations in colorectal carcinogenesis. MLH1-hypermethylated tumors harbor fewer APC and KRAS mutations and more BRAF mutations, suggesting that they develop distinctly from an MGMT methylator pathway.

Poorer outcome in stromal HIF-2 alpha- and CA9-positive colorectal adenocarcinomas is associated with wild-type TP53 but not with BNIP3 promoter hypermethylation or apoptosis.

Stromal expression of hypoxia inducible factor 2 alpha (HIF-2 alpha) and carbonic anhydrase 9 (CA9) are associated with a poorer prognosis in colorectal cancer (CRC). Tumour cell death, regulated by a hypoxic stromal microenvironment, could be of importance in this respect. Therefore, we correlated apoptosis, TP53 mutational status and BNIP3 promoter hypermethylation of CRC cells with HIF-2 alpha- and CA9-related poor outcome. In a series of 195 CRCs, TP53 mutations in exons 5-8 were analysed by direct sequencing, and promoter hypermethylation of BNIP3 was determined by methylation-specific PCR. Expressions of HIF-2 alpha, CA9, p53, BNIP3 and M30 were analysed immunohistochemically. Poorer survival of HIF-2 alpha and CA9 stromal-positive CRCs was associated with wild-type TP53 (P=0.001 and P=0.0391), but not with BNIP3 methylation. Furthermore, apoptotic levels were independent of the TP53 status, but lower in unmethylated BNIP3 CRCs (P=0.004). It appears that wild-type TP53 in CRC cells favours the progression of tumours expressing markers for hypoxia in their stroma, rather than in the epithelial compartment. Preserved BNIP3 function in CRC cells lowers apoptosis, and may thus be involved in alternative cell death pathways, such as autophagic cell death. However, BNIP3 silencing in tumour cells does not impact on hypoxia-driven poorer prognosis. These results suggest that the biology of CRC cells can be modified by alterations in the tumour microenvironment under conditions of tumour hypoxia.

Grading of dysplasia in Barrett's oesophagus: substantial interobserver variation between general and gastrointestinal pathologists.

AIMS: To determine interobserver variation in grading of dysplasia in Barrett's oesophagus (BO) between non-expert general pathologists and expert gastrointestinal pathologists on the one hand and between expert pathologists on the other hand. METHODS AND RESULTS: In this prospective multicentre study, non-expert and expert pathologists graded biopsy specimens of 920 patients with endoscopic BO, which were blindly reviewed by one member of a panel of expert pathologists (panel experts) and by a second panel expert in case of disagreement on dysplasia grade. Agreement between two of three pathologists was established as the final diagnosis. Analysis was performed by kappa statistics. Due to absence of intestinal metaplasia, 127/920 (14%) patients were excluded. The interobserver agreement for dysplasia [no dysplasia (ND) versus indefinite for dysplasia/low-grade dysplasia (IND/LGD) versus high-grade dysplasia (HGD)/adenocarcinoma (AC)] between non-experts and first panel experts and between initial experts and first panel experts was fair (kappa = 0.24 and kappa = 0.27, respectively), and substantial for differentiation of HGD/AC from ND/IND/LGD (kappa = 0.62 and kappa = 0.58, respectively). CONCLUSIONS: There was considerable interobserver variability in the interpretation of ND or IND/LGD in BO between non-experts and experts, but also between expert pathologists. This suggests that less subjective markers are needed to determine the risk of developing AC in BO.

High-grade clear cell renal cell carcinoma has a higher angiogenic activity than low-grade renal cell carcinoma based on histomorphological quantification and qRT-PCR mRNA expression profile.

Clear cell renal cell carcinoma (CC-RCC) is a highly vascularised tumour and is therefore an attractive disease to study angiogenesis and to test novel angiogenesis inhibitors in early clinical development. Endothelial cell proliferation plays a pivotal role in the process of angiogenesis. The aim of this study was to compare angiogenesis parameters in low nuclear grade (n=87) vs high nuclear grade CC-RCC (n=63). A panel of antibodies was used for immunohistochemistry: CD34/Ki-67, carbonic anhydrase IX, hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF). Vessel density (MVD - microvessel density), endothelial cell proliferation fraction (ECP%) and tumour cell proliferation fraction (TCP%) were assessed. mRNA expression levels of angiogenesis stimulators and inhibitors were determined by quantitative RT-PCR. High-grade CC-RCC showed a higher ECP% (P=0.049), a higher TCP% (P=0.009), a higher VEGF protein expression (P<0.001), a lower MVD (P< 0.001) and a lower HIF-1alpha protein expression (P=0.002) than low-grade CC-RCC. Growth factor mRNA expression analyses revealed a higher expression of angiopoietin 2 in low-grade CC-RCC. Microvessel density and ECP% were inversely correlated (Rho=-0.26, P=0.001). Because of the imperfect association of nuclear grade and ECP% or MVD, CC-RCC was also grouped based on low/high MVD and ECP%. This analysis revealed a higher expression of vessel maturation and stabilisation factors (placental growth factor, PDGFB1, angiopoietin 1) in CC-RCC with high MVD, a group of CC-RCC highly enriched in low nuclear grade CC-RCC, with low ECP%. Our results suggest heterogeneity in angiogenic activity and vessel maturation of CC-RCC, to a large extent linked to nuclear grade, and, with probable therapeutic implications.

Meat consumption and K-ras mutations in sporadic colon and rectal cancer in The Netherlands Cohort Study.

Case-cohort analyses were performed on meat and fish consumption in relation to K-ras mutations in 448 colon and 160 rectal cancers that occurred during 7.3 years of follow-up, excluding the first 2.3 years, and 2948 subcohort members of The Netherlands Cohort Study on diet and cancer. Adjusted incidence rate ratios and 95% confidence intervals were computed for colon and rectal cancer and for K-ras mutation status subgroups. Total fresh meat, most types of fresh meat and fish were not associated with colon or rectal cancer, neither overall nor with K-ras mutation status. However, several weak associations were observed for tumours with a wild-type K-ras, including beef and colon tumours, and an inverse association for pork with colon and rectal tumours; for meat products, an increased association was observed with wild-type K-ras tumours in the colon and possibly with G>A transitions in rectal tumours.

[Diagnostic image (114). A woman with pulse-synchronous tinnitus. Glomus tumor in the ear]. / Diagnose in beeld (114). Een vrouw met polssynchrone tinnitus. Glomus-tympanicumtumor.

A 58-year-old woman with pulse-synchrone tinnitus was diagnosed with a glomus tumour in the right middle ear.

Molecular imaging of cell death in intracardiac tumours: A new approach to differential diagnosis in cardiac tumours.

BACKGROUND: Primary endocardial tumours are rare, but may impose a difficult clinical problem. The definite diagnosis regarding the nature of the tumour is often made after surgery. This is due to the fact that current non-invasive imaging techniques are unable to inform us about the nature of the tumour. In addition, invasive techniques can not be used to obtain biological information of the tumour in these cases, because they carry a high risk of embolic complications. OBJECTIVE: To assess the possibility of a novel modality of imaging, molecular imaging, in the diagnosis of primary intracardiac tumours. METHODS: We evaluated two patients with a primary cardiac tumour. Prior to therapy, we infused human recombinant annexin-V Tc99-m and thallium 201. We used a dual isotope single photon emission computed tomography technique. This allowed us to obtain information about the relation between the anatomical position of the left ventricle and the uptake of the labelled annexin-V within the thoracic cavity. RESULTS: The patient with a malignant primary cardiac tumour showed uptake of labelled annexin-V within the area of the tumour. After surgery, the malignant nature was confirmed by histological analysis. The patient with a benignant intracardiac tumour showed no uptake of annexin-V within the area of the tumour. CONCLUSION: This novel imaging technique, molecular imaging, may be of help to differentiate non-invasively between a malignant and benignant primary intracardiac tumour.

Serum chromogranin A as a screening test for gastric enterochromaffin-like cell hyperplasia during acid-suppressive therapy.

BACKGROUND: Serum chromogranin A (CgA), a marker of neuroendocrine neoplasia, increases during profound gastric acid inhibition, possibly reflecting the trophic effect of gastrin on the enterochromaffin-like (ECL) cells. AIMS: This study investigated the clinical value of serum CgA as a screening test for gastric fundic enterochromaffin-like (ECL) cell hyperplasia during acid-suppressive therapy. METHOD: A consecutive series of 230 dyspeptic patients referred for upper gastrointestinal endoscopy was investigated in a cross-sectional design. They were 154 patients on continuous medium-term (6 weeks to one year) or long-term (longer than one year) acid inhibition with either proton pump inhibitors (PPIs, n = 117) or histamine2-receptor antagonists (H2RAs, n = 37) for gastro-oesophageal reflux disease, and 76 nontreated subjects, with normal endoscopic findings (control group). Fasting blood samples were analysed for gastrin and CgA. Gastric biopsy specimens (oxyntic mucosa) were examined for histological evaluation of gastritis (Sydney classification) and of ECL cell hyperplasia (Solcia classification). RESULTS: Serum CgA levels correlated positively with serum gastrin, following a quadratic function (r = 0.78, P < 0.0001). Elevated serum CgA values during long-term acid inhibition correlated with the presence and severity of fundic ECL cell hyperplasia. Multivariate analysis identified hypergastrinaemia (P < 0.0001), duration of acid inhibition (P < 0.0001), H. pylori infection (P = 0.008), ECL cell hyperplasia (P = 0.012), and body gland atrophy (P = 0.043) as independent predictors of elevated serum CgA. In subjects on long-term acid inhibition (n = 123), serum CgA was equally sensitive but more specific than serum gastrin for the detection of ECL cell hyperplasia (sensitivity, 91.3% for both; specificity, 73% vs. 43%, P < 0.0001). CONCLUSIONS: During long-term gastric acid inhibition, serum CgA levels reflect the presence and severity of fundic ECL cell hyperplasia. Serum CgA is therefore a useful screening test for gastric ECL cell proliferative changes within this context.

Is type III intestinal metaplasia an obligatory precancerous lesion in intestinal-type gastric carcinoma?

This retrospective study was performed to assess whether type III intestinal metaplasia is an obligatory precancerous lesion of intestinal-type gastric carcinoma and to determine its possible use as a marker of enhanced cancer risk. From 48 consecutive patients with gastric cancer who underwent a gastrectomy over a 3-year period (mean age 72.0 years; 29 M/19 F), at least two sections from antrum, corpus and tumour-surrounding mucosa were obtained for the examination of presence and subtypes of intestinal metaplasia (IM). It was found that 77.1% of the carcinomas were of the intestinal type and 22.9% of the diffuse type. The intestinal-type was more often found in males (P = 0.01); the mean age at diagnosis in this type was higher than in the diffuse cancer group (P = 0.004). There was a high prevalence of total IM in both the intestinal (75.7%) and diffuse group (88.9%). Type I IM was predominant in antrum and corpus of patients from both groups. Type III IM was only found among patients with intestinal-type carcinoma. However, its prevalence was rather low (26.3%). Therefore the absence of this lesion in patients with other risk factors cannot be used as an argument for lowering the degree of surveillance and its presence seems to be sufficient indication for long-term follow-up.

Evidence for a bias toward intracellular antigens in the local humoral anti-tumor immune response of a colorectal cancer patient revealed by phage display.

Many patients with colorectal carcinoma (CRC) mount a cellular as well as a humoral immune response to the tumor. To investigate the nature and specificity of the humoral immune response in a CRC patient, lymphocytes infiltrating the primary colorectal tumor and lymph nodes draining the tumor were used as antibody variable (V)-gene pools for the construction of phage antibody repertoires. These libraries were first validated by selection on the antigen tetanus toxoid and shown to contain antibodies that were probably derived from both naive and memory B cells. The repertoires were then screened for the presence of antibodies directed to CRC by selection on the cell line CaCo2. For comparison, the same selections were performed with a phage antibody repertoire made from B cells of healthy donors. Striking differences were observed in the panel of specificities selected from these different repertoires: although a large panel of antibodies reactive with patient-derived primary tumors was obtained from the immune repertoires, none of these discriminated between normal colonic epithelium and colon cancer and none were reactive with cell-surface antigens. However, selections using the non-immune library did result in numerous antibodies that recognized cell surface markers on CaCo2. These data suggest a bias in the local humoral immune response in this CRC patient, directed primarily toward intracellular epithelial-cell specific target antigens.

Double gastric infection with Helicobacter pylori and non-Helicobacter pylori bacteria during acid-suppressive therapy: increase of pro-inflammatory cytokines and development of atrophic gastritis.

BACKGROUND: Long-term acid suppression may accelerate the development of atrophic gastritis in Helicobacter pylori-positive subjects. The pathogenetic mechanism remains unclear. AIM: To test the hypothesis that gastric double infection with H. pylori and non-H. pylori bacterial species-during acid suppression-may result in an enhanced inflammatory response, contributing to the development of atrophic gastritis. PATIENTS AND METHODS: A consecutive series of patients with gastro-oesophageal reflux disease undergoing treatment with proton pump inhibitors (n=113) or histamine2-receptor antagonists (H2-RAs) (n=37), and 76 non-treated dyspeptic controls were investigated. Gastric mucosal H. pylori and non-H. pylori bacteria, histological gastritis, H. pylori serology, and circulating interleukin (IL)-1beta, IL-6, and IL-8 were examined. RESULTS: Patients on acid suppression with either proton pump inhibitors or H2-RAs had a similar prevalence of H. pylori infection to the controls, but a higher prevalence of non-H. pylori bacteria (61% and 60% vs. 29%, P < 0.0001 and P < 0.002). Both the presence of H. pylori and non-H. pylori bacteria were independent risk factors of atrophic gastritis (antrum: relative risks (RRs), 10.1 and 5.07; corpus: RRs, 11.74 and 6.38). A simultaneous presence of H. pylori and non-H. pylori bacteria was associated with a markedly increased risk of atrophic gastritis (antrum: RR, 20.25; corpus: RR, 20.38), compatible with a synergistic effect. Furthermore, the simultaneous presence of both types of bacteria was associated with higher cytokine levels than in patients without any type of bacteria. This increase was also greater than in patients with H. pylori infection alone (P < 0.001, for both IL-1beta and IL-8). SUMMARY AND CONCLUSIONS: H. pylori-positive patients on long-term acid inhibition displayed three features: non-H. pylori bacterial growth; increased cytokine levels; and a higher risk of atrophic gastritis. We suggest that double infection with H. pylori and non-H. pylori bacteria is a major factor in the development of atrophic gastritis during gastric acid inhibition.

In vitro characterisation of a monovalent and bivalent form of a fully human anti Ep-CAM phage antibody.

Antibodies to tumour-associated antigens are increasingly being used as targeting vehicles for the visualisation and for therapy of human solid tumours. The epithelial cell adhesion molecule (Ep-CAM) is an antigen that is overexpressed on a variety of human solid tumours and constitutes an attractive target for immunotargeting. We set out to obtain fully human antibodies to this antigen by selecting from a large antibody repertoire displayed on bacteriophages. Two single-chain variable antibody fragments (scFv) were identified that specifically bound recombinant antigen in vitro. One of the selected antibodies (VEL-1) cross-reacted with extracellular matrix components in immunohistochemistry of colon carcinoma, whereas the other scFv (VEL-2) specifically recognised colon cancer cells. The latter antibody was further characterised with respect to epitope specificity and kinetics of antigen-binding. It showed no competition with the well-characterised anti Ep-CAM MOC-31 monoclonal antibody and had an off-rate of 5 x 10(-2) s-1. To obtain an antibody format more suitable for in vivo tumour targeting and to increase the apparent affinity through avidity, the genes of scFv VEL-2 were re-formatted by fusion to a human (gamma 1) hinge region and CH3 domain. This "minibody" was expressed in Escherichia coli, specifically bound the Ep-CAM antigen and showed a 20-fold reduced off-rate in surface plasmon resonance analysis. These results show that phage antibody selection, combined with antibody engineering, may result in fully human antibody molecules with promising characteristics for in vivo use in tumour targeting.

Identification of colon tumour-associated antigens by phage antibody selections on primary colorectal carcinoma.

Immunotargeting of solid tumours using antibodies has become a valuable tool for the detection of cancer metastases and the treatment of minimal residual disease. However, only few tumour antigens useful for targeting have been described to date. To identify cell-surface targets on colorectal carcinoma (CRC), we selected a large, human phage antibody repertoire on freshly isolated colon tumour cells. Two antibodies were identified that reacted with epithelial cell-restricted cell-surface antigens, whereas one clone preferentially reacted with stromal cells. These antigens are tumour-associated antigens, as shown by their uniform expression in tumours of different patients and of different differentiation stages and by their limited expression on normal tissues. The pattern of reactivity in immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA) suggests that these antigens are different from previously identified tumour-associated antigens (e.g. Ep-CAM or c-ERB-2). This phage antibody-based method may lead to the cloning of novel tumour antigens that are useful for the immunotargeting of solid tumours.

Accuracy of magnetic resonance imaging in prediction of tumour-free resection margin in rectal cancer surgery.

BACKGROUND: Incomplete surgical removal of the circumferential tumour spread is believed to be the main cause of local recurrence after resection of rectal cancer. This study assessed the accuracy of magnetic resonance imaging (MRI) with a phased-array coil for preoperative staging and prediction of the distance of the tumour from the circumferential resection margin in a total mesorectal excision. METHODS: 76 patients with primary rectal cancer were preoperatively assessed by MRI at 1.5 T, with a phased-array coil. Two observers independently scored, on two occasions, the tumour stage and measured the distance to the mesorectal fascia. Their findings were compared with the final histological findings. FINDINGS: The MRI tumour stage agreed with the histological stage in 63 (83%) of 76 patients (weighted kappa=0.77 [95% CI 0.66-0.89]) for observer 1, and in 51 (67%) patients (weighted kappa=0.52 [0.37-0.67]) for observer 2. The intraobserver agreement on the tumour stage was good (kappa=0.80 [0.69-0.91]) for observer 1 but moderate (kappa=0.49 [0.34-0.65]) for observer 2. The interobserver agreement was moderate (kappa=0.53 [0.38-0.69]). In 12 patients with an obvious T4 tumour, a margin of 0 mm was correctly predicted. Of 29 patients for whom the pathologist reported a distance of at least 10 mm without specifying the actual distance, a distance of at least 10 mm was predicted in 28 by observer 1 and 27 by observer 2. For the remaining 35 patients, a regression curve was constructed; from this, a histological distance of at least 1.0 mm can be predicted with high confidence when the measured distance on MRI is at least 5.0 mm. INTERPRETATION: MRI with a phased-array coil showed moderate accuracy and reproducibility for predicting the tumour stage of rectal cancers. The clinically more important circumferential resection margin can, however, be predicted with high accuracy and consistency, allowing preoperative identification of patients at risk of recurrence who will benefit from preoperative radiotherapy, more extensive surgery, or both.