Johannes Betge

Intramural and extramural vascular invasion in colorectal cancer: prognostic significance and quality of pathology reporting.

Blood vessel invasion has been associated with poor outcome in colorectal cancer (CRC), whereas the prognostic impact of lymphatic invasion is less clear. The authors of this report evaluated venous and lymphatic invasion as potential prognostic indicators in patients with CRC focusing on lymph node‐negative patients and compared routine and review pathology diagnoses.

Amplicon Sequencing of Colorectal Cancer: Variant Calling in Frozen and Formalin-Fixed Samples

Next generation sequencing (NGS) is an emerging technology becoming relevant for genotyping of clinical samples. Here, we assessed the stability of amplicon sequencing from formalin-fixed paraffin-embedded (FFPE) and paired frozen samples from colorectal cancer metastases with different analysis pipelines. 212 amplicon regions in 48 cancer related genes were sequenced with Illumina MiSeq using DNA isolated from resection specimens from 17 patients with colorectal cancer liver metastases. From ten of these patients, paired fresh frozen and routinely processed FFPE tissue was available for comparative study. Sample quality of FFPE tissues was determined by the amount of amplifiable DNA using qPCR, sequencing libraries were evaluated using Bioanalyzer. Three bioinformatic pipelines were compared for analysis of amplicon sequencing data. Selected hot spot mutations were reviewed using Sanger sequencing. In the sequenced samples from 16 patients, 29 non-synonymous coding mutations were identified in eleven genes. Most frequent were mutations in TP53 (10), APC (7), PIK3CA (3) and KRAS (2). A high concordance of FFPE and paired frozen tissue samples was observed in ten matched samples, revealing 21 identical mutation calls and only two mutations differing. Comparison of these results with two other commonly used variant calling tools, however, showed high discrepancies. Hence, amplicon sequencing can potentially be used to identify hot spot mutations in colorectal cancer metastases in frozen and FFPE tissue. However, remarkable differences exist among results of different variant calling tools, which are not only related to DNA sample quality. Our study highlights the need for standardization and benchmarking of variant calling pipelines, which will be required for translational and clinical applications.

Apelin: A putative novel predictive biomarker for bevacizumab response in colorectal cancer

Bevacizumab (bvz) is currently employed as an anti-angiogenic therapy across several cancer indications. Bvz response heterogeneity has been well documented, with only 10-15% of colorectal cancer (CRC) patients benefitting in general. For other patients, clinical efficacy is limited and side effects are significant. This reinforces the need for a robust predictive biomarker of response. To identify such a biomarker, we performed a DNA microarray-based transcriptional profiling screen with primary endothelial cells (ECs) isolated from normal and tumour colon tissues. Thirteen separate populations of tumour-associated ECs and 10 of normal ECs were isolated using fluorescence-activated cell sorting. We hypothesised that VEGF-induced genes were overexpressed in tumour ECs; these genes could relate to bvz response and serve as potential predictive biomarkers. Transcriptional profiling revealed a total of 2,610 differentially expressed genes when tumour and normal ECs were compared. To explore their relation to bvz response, the mRNA expression levels of top-ranked genes were examined using quantitative PCR in 30 independent tumour tissues from CRC patients that received bvz in the adjuvant setting. These analyses revealed that the expression of MMP12 and APLN mRNA was significantly higher in bvz non-responders compared to responders. At the protein level, high APLN expression was correlated with poor progression-free survival in bvz-treated patients. Thus, high APLN expression may represent a novel predictive biomarker for bvz unresponsiveness.

Tumor size, tumor location, and antitumor inflammatory response are associated with lymph node size in colorectal cancer patients

Lymph node size affects lymph node retrieval in surgical specimen and is used as criterion for pre-operative radiological estimation of metastatic disease. However, factors determining lymph node size remain to be established. Therefore, the association between lymph node size and presence of metastatic cancer deposits as well as different primary tumor characteristics was analyzed in a prospective cross-sectional study. Visible and palpable nodes were harvested, and conventional histology, immunohistochemistry, and molecular analysis were performed. The study cohort comprised 148 patients (median age 69 years, range 36–92). Lymph node dissection rendered 4167 nodes. Mean lymph node count was 28 (median 26, range 9–67). Metastatic disease was detected in 320 (8%) nodes and was associated with lymph node size (P<0.001). Positive nodes measuring ≤2 mm caused upstaging within the N category in one third of cases, but did not identify patients as node-positive as all patients also had positive larger nodes. Large tumor size (P=0.001), right tumor location (P<0.001), and deep tumor penetration (P=0.024) were all independently associated with lymph node size, whereas high lymphocytic antitumor reaction just missed statistical significance (P=0.053) in multivariable analysis. Microsatellite instability had no influence on lymph node size when analysis was restricted to right-sided tumors. In conclusion, analysis of small lymph nodes may lead to upstaging within the N category, but they do not identify a patient as node-positive and do therefore not influence clinical decision-making in the adjuvant setting. The majority of enlarged lymph nodes, including those measuring >1 cm, are not involved by cancer. Different tumor characteristics, such as large primary tumor size, right tumor location, and deep tumor penetration are independently associated with lymph node size and need to be considered when interpreting enlarged nodes detected by radiological imaging.

Risk Factors for Local Recurrence of Large, Flat Colorectal Polyps after Endoscopic Mucosal Resection

Aims: Removal of large, flat colorectal polyps by endoscopic mucosal resection (EMR) is effective, but local recurrences occur regularly. This study investigated risk factors for local recurrence. Method: Cases of EMR of flat colorectal polyps ≥20 mm at an academic center from 2004 to 2011 were retrospectively analyzed for polyp features, resection technique, complications and local recurrences. Behavioral risk factors were retrospectively determined by self-administered questionnaires. Results: Data were collected for 129 patients (57.3% male, mean age at time of EMR: 65.0 years). Mean polyp size was 37.2 mm. Polyps were mostly adenoma with low-grade dysplasia (58.1%) and predominantly located in the right colon (62%). En bloc resection was performed in 31.8%. The median follow-up time was 40 months. Local recurrence occurred in 26.3% of patients, with 87% being recurrence-free after 1 year (95% CI 81-93%). A history of smoking was reported by 51.6% of patients and 88.4% reported regular alcohol consumption. Univariate analysis showed that polyp size and piecemeal resection were associated with risk of local recurrence. In multivariate analysis, only polyp size was predictive for local recurrence. No association was found for behavioral risk factors. Conclusion: Polyp size is the main predictor of local recurrence after EMR of large, flat colorectal polyps.

Is there a rationale to record lymphatic invasion in node-positive colorectal cancer?

This study aimed to evaluate the prognostic significance of lymphatic invasion in colorectal cancers that have already spread to regional lymph nodes. 168 patients with node-positive tumours (colon, n=98; rectum, n=70) were retrospectively evaluated. Lymphatic invasion was assessed on H&E stained slides and univariable and multivariable analyses were applied. Lymphatic invasion was detected in 95 (57%) cases and was significantly associated with tumour and node classification and tumour differentiation. Patients with tumours showing lymphatic invasion had decreased progression-free survival (p=0.025) and cancer-specific survival (p=0.082). Stratified by location, lymphatic invasion was significantly associated with decreased progression-free (p=0.010) and cancer-specific (p=0.023) survival in colon cancers, yet not in rectal cancers. Multivariable analysis proved T4 (HR 2.18, 95% CI 1.40 to 3.39; p<0.001) and N2 (HR 1.68, 95% CI 1.07 to 2.66; p=0.03) as independent predictors of progression-free survival and T4 (HR 1.90, 95% CI 1.17 to 3.07; p=0.009), N2 (HR 2.27, 95% CI 1.38 to 3.73; p=0.001) and poor tumour differentiation (HR 2.18, 95% CI 1.39 to 3.43; p<0.001) as independent predictors of cancer-specific survival, while for lymphatic invasion no influence on outcome was noted. In conclusion, only tumour and node classification, and tumour differentiation proved to be independent prognostic variables in node-positive colorectal cancer and merit special attention in clinical decision-making.

Loss of Chromosome 18q11.2-q12.1 Is Predictive for Survival in Patients With Metastatic Colorectal Cancer Treated With Bevacizumab

Purpose Patients with metastatic colorectal cancer (mCRC) have limited benefit from the addition of bevacizumab to standard chemotherapy. However, a subset probably benefits substantially, highlighting an unmet clinical need for a biomarker of response to bevacizumab. Previously, we demonstrated that losses of chromosomes 5q34, 17q12, and 18q11.2-q12.1 had a significant correlation with progression-free survival (PFS) in patients with mCRC treated with bevacizumab in the CAIRO2 clinical trial but not in patients who did not receive bevacizumab in the CAIRO trial. This study was designed to validate these findings. Materials and Methods Primary mCRC samples were analyzed from two cohorts of patients who received bevacizumab as first-line treatment; 96 samples from the European multicenter study Angiopredict (APD) and 81 samples from the Italian multicenter study, MOMA. A third cohort of 90 samples from patients with mCRC who did not receive bevacizumab was analyzed. Copy number aberrations of tumor biopsy specimens were measured by shallow whole-genome sequencing and were correlated with PFS, overall survival (OS), and response. Results Loss of chromosome 18q11.2-q12.1 was associated with prolonged PFS most significantly in both the cohorts that received bevacizumab (APD: hazard ratio, 0.54; P = .01; PFS difference, 65 days; MOMA: hazard ratio, 0.55; P = .019; PFS difference, 49 days). A similar association was found for OS and overall response rate in these two cohorts, which became significant when combined with the CAIRO2 cohort. Median PFS in the cohort of patients with mCRC who did not receive bevacizumab and in the CAIRO cohort was similar to that of the APD, MOMA, and CAIRO2 patients without an 18q11.2-q12.1 loss. Conclusion We conclude that the loss of chromosome 18q11.2-q12.1 is consistently predictive for prolonged PFS in patients receiving bevacizumab. The predictive value of this loss is substantiated by a significant gain in OS and overall response rate.

Adjuvant chemotherapy improves survival in patients with American Joint Committee on Cancer stage II colon cancer

With great interest we read the article by McKenzie et al, who demonstrated a survival advantage for adjuvant chemotherapy in patients with American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) stage II colon cancer in a population-based analysis illustrating that select patients with AJCC/UICC stage II disease should be given adjuvant treatment. In the study by McKenzie et al, selection criteria for adjuvant treatment were not defined. However, when grouped according to receipt of adjuvant chemotherapy, patients who received chemotherapy were disproportionately younger, had larger tumors located more frequently in the descending or sigmoid colon, and were more likely to have 12 lymph nodes examined. In our opinion, the pathology report represents the basis for risk stratification and consequently selection of patients for adjuvant treatment. In our recent study published in this journal, we proved that venous invasion was an independent prognostic variable in patients with AJCC/UICC stage II disease. Inspired by the current publication, we enlarged our multivariable analysis. Analyzing 108 patients with stage II colorectal cancer in a Cox regression model, T4 tumors (hazard ratio [HR] 17.51; 95% confidence interval [CI], 4.04-75.80; P < .001), venous invasion (HR, 8.46; 95% CI,2.03-35.12; P 1⁄4 .003), and examination of <12 lymph nodes (HR, 3.45; 95% CI, 1.09-10.26; P1⁄4 .035) were associated significantly with cancer-related death. No impact on outcome was noted for age, sex, tumor size and grade, or lymphatic invasion. With respect to progression-free survival, similar results were obtained (data not shown). Our data are well in line with the report by McKenzie et al, in which sampling of >12 lymph nodes was associated significantly with favorable outcome. Stocchi et al recently presented similar data indicating that <12 examined lymph nodes and T4 tumors are independent predictors of poor patient outcome, yet they did not include venous invasion in their analysis. In conclusion, patients with AJCC/UICC stage II disease who have tumors characterized by T4 classification, venous invasion, or <12 lymph nodes examined are more likely to die from disease. Thus, these 3 markers, which can be obtained easily during the routine pathologic work-up of cancer specimens, may well be used to select patients for adjuvant therapy. REFERENCES

CRISPR/Cas9 for cancer research and therapy

CRISPR/Cas9 has become a powerful method for making changes to the genome of many organisms. First discovered in bacteria as part of an adaptive immune system, CRISPR/Cas9 and modified versions have found a widespread use to engineer genomes and to activate or to repress the expression of genes. As such, CRISPR/Cas9 promises to accelerate cancer research by providing an efficient technology to dissect mechanisms of tumorigenesis, identify targets for drug development, and possibly arm cells for cell-based therapies. Here, we review current applications of the CRISPR/Cas9 technology for cancer research and therapy. We describe novel Cas9 variants and how they are used in functional genomics to discover novel cancer-specific vulnerabilities. Furthermore, we highlight the impact of CRISPR/Cas9 in generating organoid and mouse models of cancer. Finally, we provide an overview of the first clinical trials that apply CRISPR/Cas9 as a therapeutic approach against cancer.

Outcome of Colorectal Cancer Patients Treated with Combination Bevacizumab Therapy: A Pooled Retrospective Analysis of Three European Cohorts from the Angiopredict Initiative

Background/Aims: This study is aimed at analyzing the survival rates and prognostic factors of stage IV colorectal cancer patients from 3 European cohorts undergoing combination chemotherapy with bevacizumab. Methods: Progression free-survival (PFS) and overall survival (OS) were analyzed in 172 patients using the Kaplan-Meier method and uni- and multivariable Cox proportional hazards regression models. Results: The median PFS was 9.7 and the median OS 27.4 months. Patients treated at centers in Germany (n = 97), Ireland (n = 32), and The Netherlands (n = 43) showed a median PFS of 9.9, 9.2, and 9.7 months, OS of 34.0, 20.5, and 25.1 months, respectively. Patients >65 years had a significantly shorter PFS (9.5 vs. 9.8 months) but not OS (27.4 vs. 27.5 months) than younger patients. High tumor grade (G3/4) was associated with a shorter PFS, T4 classification with both shorter PFS and OS. Fluoropyrimidine (FP) chemotherapy backbones (doublets and single) had comparable outcomes, while patients not receiving FP backbones had a shorter PFS. In multivariable analysis, age and non-FP backbone were associated with inferior PFS, T4 classification and therapy line >2nd were significantly associated with poor PFS and OS. Conclusion: The observed survival rates confirm previous studies and demonstrate reproducible benefits of combination bevacizumab regimens. Classification T4, non-FP chemotherapy backbone, and age >65 were associated with inferior outcome.