Prediction of Response to Immune Checkpoint Blockade in Patients with Metastatic Colorectal Cancer with Microsatellite Instability

BACKGROUND

Mismatch repair deficient (dMMR) tumors displaying microsatellite instability (MSI) represent a paradigm for the success of immune checkpoint inhibitor (ICI)-based immunotherapy, particularly in patients with metastatic colorectal cancer (mCRC). However, a proportion of patients with dMMR/MSI mCRC exhibit resistance to ICI. Identification of tools predicting MSI mCRC patient response to ICI are required for the design of future strategies further improving this therapy.

PATIENTS AND METHODS

We combined high-throughput DNA and RNA sequencing of tumors from 116 patients with MSI mCRC treated with anti-PD-1 +/- anti-CTLA-4 of the NIPICOL phase II trial (C1, NCT03350126, discovery set) and the IMMUNOMSI prospective cohort (C2, validation set). The DNA/RNA predictors whose status was significantly associated with ICI status of response in C1 were subsequently validated in C2. Primary endpoint was iPFS (progression-free survival by iRECIST).

RESULTS

Analyses showed no impact of previously suggested DNA/RNA indicators of resistance to ICI, e.g., MSISensor score, tumor mutational burden, or specific cellular and molecular tumoral contingents. By contrast, iPFS under ICI was shown in C1 and C2 to depend both on a multiplex MSI signature involving the mutations of 19 microsatellites (HR_C2 = 3.63; 95% CI [1.65-7.99] ; p = 1.4x10^-3) and the expression of a set of 182 RNA markers with a non-epithelial TGFB-related desmoplastic orientation (HR_C2 = 1.75 ; 95% CI [1.03-2.98] ; p = 0.035). Both DNA and RNA signatures were independently predictive of iPFS.

CONCLUSIONS

iPFS in patients with MSI mCRC can be predicted by simply analyzing the mutational status of DNA microsatellite-containing genes in epithelial tumor cells together with nonepithelial TGFB-related desmoplastic RNA markers.

ECCO Position on Harmonisation of Crohn's Disease Mucosal Histopathology

In inflammatory bowel disease [IBD], mucosal healing is a major therapeutic target and a reliable predictor of clinical course. However, endoscopic mucosal healing is not synonymous with histological healing, and the additional benefits of including histological remission as a target are unclear. In Crohn´s disease [CD], there are few studies highlighting the value of histological remission as a therapeutic target. Histological activity can persist in CD patients who are in endoscopic remission, and the absence of histological activity may be associated with lower relapse rates. Therefore, standardisation of procedures to evaluate CD histological activity is desirable. Topics that would benefit from standardisation and harmonisation include biopsy procedures, biopsy processing techniques, the content of histological scores, and the definitions of histological remission, histological response, and histological activity. In line with these needs, the European Crohn's and Colitis Organisation [ECCO] assembled a consensus group with the objective of developing position statements on CD histology based on published evidence and expert consensus. There was agreement that definitions of histological remission should include absence of erosion, ulceration, and mucosal neutrophils; that the absence of neutrophilic inflammation is an appropriate histological target in CD; that CD histological scores, such as the Global Histological Disease Activity Score, lack formal validation; and that histological scoring systems for ulcerative colitis, including the Geboes Score, Robarts Histopathology Index, and Nancy Histological Index, can be used for scoring intestinal biopsies in CD patients.

Relevance of biopsy-derived pancreatic organoids in the development of efficient transcriptomic signatures to predict adjuvant chemosensitivity in pancreatic cancer

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Most patient with pancreatic cancer are treated by chemotherapy.

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Treatments selection are not personalized on the tumor characteristics.

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Signatures predicting chemotherapy efficiency are essential for personalizing treatments.

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An RNA signature of gemcitabine-sensitivity is developed leveraged on the dissimilarities between 2D and 3D in vitro models.

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Combining different in vitro models can help in defining clinically efficient transcriptomic signatures.

Pancreatic ductal adenocarcinoma (PDAC) patients are frequently treated by chemotherapy. Even if personalized therapy based on molecular analysis can be performed for some tumors, PDAC regimens selection is still mainly based on patients' performance status and expected efficacy. Therefore, the establishment of molecular predictors of chemotherapeutic efficacy could potentially improve prognosis by tailoring treatments. We have recently developed an RNA-based signature that predicts the efficacy of adjuvant gemcitabine using 38 PDAC primary cell cultures. While demonstrated its efficiency, a significant association with the classical/basal-like PDAC spectrum was observed. We hypothesized that this flaw was due to the basal-like biased phenotype of cellular models used in our strategy. To overcome this limitation, we generated a prospective cohort of 27 consecutive biopsied derived pancreatic organoids (BDPO) and include them in the signature identification strategy. As BDPO's do not have the same biased phenotype as primary cell cultures we expect they can compensate one with each other and cover a broader range of molecular phenotypes. We then obtained an improved signature predicting gemcitabine sensibility that was validated in a cohort of 300 resected PDAC patients that have or have not received adjuvant gemcitabine. We demonstrated a significant association between the improved signature and the overall and disease-free survival in patients predicted as sensitive and treated with adjuvant gemcitabine. We propose then that including BDPO along primary cell cultures represent a powerful strategy that helps to overcome primary cell cultures limitations producing unbiased RNA-based signatures predictive of adjuvant treatments in PDAC.

Combining tumor deposits with the number of lymph node metastases to improve the prognostic accuracy in stage III colon cancer: a post hoc analysis of the CALGB/SWOG 80702 phase III study (Alliance)☆

BACKGROUND

In colon cancer, tumor deposits (TD) are considered in assigning prognosis and staging only in the absence of lymph node metastasis (i.e. stage III pN1c tumors). We aimed to evaluate the prognostic value of the presence and the number of TD in patients with stage III, node-positive colon cancer.

PATIENTS AND METHODS

All participants from the CALGB/SWOG 80702 phase III trial were included in this post hoc analysis. Pathology reports were reviewed for the presence and the number of TD, lymphovascular and perineural invasion. Associations with disease-free survival (DFS) and overall survival (OS) were evaluated by multivariable Cox models adjusting for sex, treatment arm, T-stage, N-stage, lymphovascular invasion, perineural invasion and lymph node ratio.

RESULTS

Overall, 2028 patients were included with 524 (26%) TD-positive and 1504 (74%) TD-negative tumors. Of the TD-positive patients, 80 (15.4%) were node negative (i.e. pN1c), 239 (46.1%) were pN1a/b (<4 positive lymph nodes) and 200 (38.5%) were pN2 (≥4 positive lymph nodes). The presence of TD was associated with poorer DFS [adjusted hazard ratio (aHR) = 1.63, 95% CI 1.33-1.98] and OS (aHR = 1.59, 95% CI 1.24-2.04). The negative effect of TD was observed for both pN1a/b and pN2 groups. Among TD-positive patients, the number of TD had a linear negative effect on DFS and OS. Combining TD and the number of lymph node metastases, 104 of 1470 (7.1%) pN1 patients were re-staged as pN2, with worse outcomes than patients confirmed as pN1 (3-year DFS rate: 65.4% versus 80.5%, P = 0.0003; 5-year OS rate: 87.9% versus 69.1%, P = <0.0001). DFS was not different between patients re-staged as pN2 and those initially staged as pN2 (3-year DFS rate: 65.4% versus 62.3%, P = 0.4895).

CONCLUSION

Combining the number of TD and the number of lymph node metastases improved the prognostication accuracy of tumor-node-metastasis (TNM) staging.

Discordance between immunochemistry of mismatch repair proteins and molecular testing of microsatellite instability in colorectal cancer

Background

DNA mismatch repair system deficiency (dMMR) is found in 15% of colorectal cancers (CRCs). Two methods are used to determine dMMR, immunohistochemistry (IHC) of MMR proteins and molecular testing of microsatellite instability (MSI). Only studies with a low number of patients have reported rates of discordance between these two methods, ranging from 1% to 10%.

Materials and methods

Overall, 3228 consecutive patients with CRCs from two centers were included. Molecular testing was carried out using the Pentaplex panel and IHC evaluated four (MLH1, MSH2, MSH6, and PMS2; cohort 1; n = 1085) or two MMR proteins (MLH1 and MSH2; cohort 2; n = 2143). The primary endpoint was the rate of discordance between MSI and MMR IHC tests.

Results

Fifty-one discordant cases (1.6%) were initially observed. Twenty-nine out of 51 discordant cases were related to IHC misclassifications. In cohort 1, after re-reading IHC and/or carrying out new IHC, 16 discordant cases were reclassified as nondiscordant. In cohort 2, after the addition of MSH6/PMS2 IHC and re-examination, 13 were reclassified as nondiscordant. In addition, 10 misclassifications of molecular tests were identified. Finally, only 12 discordant cases (0.4%) remained: 5 were proficient MMR/MSI and 7 were dMMR/microsatellite stable.

Conclusions

Our study confirmed the high degree of concordance between MSI and MMR IHC tests. Discordant cases must be reviewed, and if needed, tests must be repeated and analyzed by an expert team.

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Concordance between MMR IHC (four proteins) and MSI molecular testing (Pentaplex) is superior to 98% in CRC cases

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Most discordant cases are related to misinterpretation of the tests, which may lead to clinical management errors.

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Discordant cases must be reviewed and tests must be repeated because most cases will be reclassified as nondiscordant.

Prognostic and predictive value of the Immunoscore in stage III colon cancer patients treated with oxaliplatin in the prospective IDEA France PRODIGE-GERCOR cohort study

BACKGROUND

The Immunoscore (IS), which prognostically classifies stage I-III colon cancer (CC) patients, was evaluated in the International Duration Evaluation of Adjuvant Therapy (IDEA) France cohort study investigating 3 versus 6 months of oxaliplatin-based adjuvant chemotherapy in stage III CC patients.

PATIENTS AND METHODS

Densities of CD3+ and CD8+ T cells in the tumor and invasive margin were determined by immunohistochemistry, quantified by digital pathology, and converted to IS. Mismatch repair status was determined by immunohistochemistry or by pentaplex PCR. Prediction of disease-free survival (DFS) by IS was analyzed by a multivariable Cox regression model in each study arm. Harrell's C-statistics were used to investigate the IS performance.

RESULTS

Samples of 1322 patients were available. IS Low, Intermediate (Int), and High were observed in 43.6%, 47.0%, and 9.4% of patients, respectively. IS Low identified patients at higher risk of relapse or death compared with Int + High [hazard ratio (HR) = 1.54; 95% confidence interval (CI) 1.24-1.93, P = 0.0001]. The 3-year DFS was 66.80% (95% CI 62.23-70.94) for IS Low and 77.14% (95% CI 73.50-80.35) for IS Int + High. In multivariable analysis, IS remained significantly independently associated with DFS (P = 0.003) when adjusted for sex, histological grade, T/N stage, and microsatellite instability. For mFOLFOX6-treated patients (91.6% of the cohort), a statistical significant interaction was observed for the predictive value of IS for treatment duration (3 versus 6 months) in terms of DFS (P = 0.057). IS Int + High significantly predicted benefit of 6 months of treatment (HR = 0.53; 95% CI 0.37-0.75; P = 0.0004), including clinically low- and high-risk stage III CC (all P < 0.001). Conversely, patients with IS Low (46.4%) did not significantly benefit from the 6-month mFOLFOX6 versus the 3-month mFOLFOX6.

CONCLUSIONS

The prognostic value of IS for DFS was confirmed in patients with stage III CC treated with oxaliplatin-based chemotherapy. Its predictive value for DFS benefit of longer duration of mFOLFOX6 adjuvant treatment was found in IS Int + High. These results will be validated in an external independent cohort. CLINICALTRIALS.

GOV REGISTRATION

NCT03422601; EudraCT Number: 2009-010384-16.

Oxaliplatin, 5-Fluorouracil and Nab-paclitaxel as perioperative regimen in patients with resectable gastric adenocarcinoma: A GERCOR phase II study (FOXAGAST)

BACKGROUND

5-Fluorouracil (5-FU) and platinum-based perioperative chemotherapy is standard of care for resectable gastric adenocarcinoma (RGA). Nanoparticle albumin-bound (Nab-) paclitaxel is active in advanced disease but has never been evaluated in the perioperative setting. The objective was to evaluate the efficacy of Nab-paclitaxel in combination with FOLFOX for RGA patients.

METHODS

We performed a non-randomised, open-label, phase II study. RGA patients were assigned to receive neoadjuvant Nab-paclitaxel (150 mg/m²) and FOLFOX q2w for six cycles. Six additional post-operative cycles were kept at the investigator's discretion. The primary end-point was complete pathological response (tumour regression grade [TRG1]) rate. According to Fleming design, 49 patients were required to test H₀ (10% TRG1) and H₁ (25% TRG1). To reject H₀, TRG1 had to be achieved in 8 patients.

RESULTS

Forty-nine patients were included. Median number of neoadjuvant chemotherapy cycles was 6 (range, 3-6). Median dose intensity for Nab-paclitaxel, oxaliplatin and 5-FU was 96% (38-103%), 97% (47-103%) and 99% (50-112%), respectively. Surgery could not be performed in 5 (10.2%) patients. Tumour resection was R0 for 42 of 44 (95.5%) patients. Pathological review classified tumours as TRG1 to TRG5 for 8 (16.3%), 11 (22.5%), 4 (8.2%), 18 (36.7%) and 3 (6.1%) patients, respectively. Grade 3 or worse toxicities during neoadjuvant chemotherapy were non-febrile neutropenia (20.4%), nausea (8.2%), diarrhoea (8.2%) and neuropathy (6.1%). Of 44 patients, 14 (31.8%) experienced surgery-related complications and three (6.8%) died of surgical complications.

CONCLUSION

This regimen shows promising activity. Toxicity is manageable but a meaningful rate of surgical complications was observed. This strategy deserves investigation in phase III studies.

Prognostic value and characteristics of N1c colorectal cancer

AIM

The presence of tumour deposits (TDs) in colorectal cancer (CRC) is associated with poor prognosis. The seventh edition of TNM subclassified a new nodal stage, N1c, characterized by the presence of TDs without any concurrent positive lymph node (LN). It is not clear if the N1c category is or is not equal to LN metastasis. We aimed to examine the prevalence, characteristics and prognostic significance of this new subcategory.

METHOD

Consecutive patients who underwent surgery for CRC in two centres (2011-2014) were analysed. N1 cM0 patients were matched against non-N1 cM0 (N0, N1a and N1b) patients for 3-year overall survival (OS) and disease-free survival (DFS).

RESULTS

We identified 1122 patients with 648 (57.8%) colonic cancers. In 57 patients (5.1%), N1c status was associated with rectal cancers [rectum = 33/57 (57.9%) vs colon = 24/57 (42.1%); P = 0.029], a higher pathological tumour stage [pT3-T4 N1c = 55/843 (6.5% vspT3-T4 non-N1c = 2/279 (0.7%); P < 0.0001] and vascular emboli [n = 35 (61.4%) vs n = 552 (51.8%); P = 0.0305]. Synchronous metastasis was observed in 23 cases (40%). After a mean follow-up of 31 months, 3-year OS for M0 patients, was 89.4%, 89.1%, 86.6% and 81.8% for N0, N1a, N1b and N1c tumours, respectively. DFS was significantly worse for N1c than for N0 (P = 0.0169), with N1c status having a significant effect on DFS in colonic cancers (P = 0.014). The presence of more than one TD was associated with a significantly worse DFS (P = 0.021).

CONCLUSION

Our results indicate that N1c CRC patients should be included among high-risk patients for whom it is widely accepted that adjuvant chemotherapy should be considered.

Clinical and molecular characterisation of hereditary and sporadic metastatic colorectal cancers harbouring microsatellite instability/DNA mismatch repair deficiency

BACKGROUND

Patients treated with chemotherapy for microsatellite unstable (MSI) and/or mismatch repair deficient (dMMR) cancer metastatic colorectal cancer (mCRC) exhibit poor prognosis. We aimed to evaluate the relevance of distinguishing sporadic from Lynch syndrome (LS)-like mCRCs.

PATIENTS AND METHODS

MSI/dMMR mCRC patients were retrospectively identified in six French hospitals. Tumour samples were screened for MSI, dMMR, RAS/RAF mutations and MLH1 methylation. Sporadic cases were molecularly defined as those displaying MLH1/PMS2 loss of expression with BRAFV600E and/or MLH1 hypermethylation and no MMR germline mutation.

RESULTS

Among 129 MSI/dMMR mCRC patients, 81 (63%) were LS-like and 48 (37%) had sporadic tumours; 22% of MLH1/PMS2-negative mCRCs would have been misclassified using an algorithm based on local medical records (age, Amsterdam II criteria, BRAF and MMR statuses when locally tested), compared to a systematical assessment of MMR, BRAF and MLH1 methylation statuses. In univariate analysis, parameters associated with better overall survival were age (P < 0.0001), metastatic resection (P = 0.001) and LS-like mCRC (P = 0.01), but not BRAFV600E. In multivariate analysis, age (hazard ratio (HR) = 3.19, P = 0.01) and metastatic resection (HR = 4.2, P = 0.001) were associated with overall survival, but not LS. LS-like patients were associated with more frequent liver involvement, metastatic resection and better disease-free survival after metastasectomy (HR = 0.28, P = 0.01). Median progression-free survival of first-line chemotherapy was similar between the two groups (4.2 and 4.2 months; P = 0.44).

CONCLUSIONS

LS-like and sporadic MSI/dMMR mCRCs display distinct natural histories. MMR, BRAF mutation and MLH1 methylation testing should be mandatory to differentiate LS-like and sporadic MSI/dMMR mCRC, to determine in particular whether immune checkpoint inhibitors efficacy differs in these two populations.

Is the assessment of submucosal invasion still useful in the management of early rectal cancer? A study of 91 consecutive patients

AIM

The only studies on the prognosis of T1 tumours are old and investigate colic and rectal cancers. Very few studies use Kikuchi's classification (of dividing submucosa into three strata) to evaluate the depth of the submucosal invasion. This study aimed to assess the pathological risk factors for lymph node metastasis (LNM), and the pathological and oncological results of patients with early rectal cancer (ERC, pT1 tumour).

METHOD

Between 2000 and 2014, 91 consecutive patients undergoing surgery [primary total mesorectal excision (TME) or local excision (LE) alone, or LE followed by TME] for ERC were included.

RESULTS

Eighteen patients underwent LE, 22 underwent LE followed by TME and 51 underwent primary total TME. After TME (n = 73), 16 (23%) patients had LNM. The LNM rate was 15% for Sm1 tumours, 14% for Sm2 tumours and 30% for Sm3 tumours. In multivariate analysis, lymphovascular invasion (P = 0.027) and high tumour budding (P = 0.037) were the only independent factors predictive of LNM. The depth of submucosal invasion was not associated with an increased risk of LNM. After a mean follow up of 56 ± 46 months, 5-year overall survival, specific survival and disease-free survival were, respectively, 82%, 93% and 75%. No significant difference of survival was found according to the depth of submucosal invasion or to the surgical management.

CONCLUSION

Histological features seem to be stronger risk factors for LNM than depth of submucosal invasion. Considering the LNM rate, TME should be discussed after LE in terms of one of these pathological criteria.

Para-aortic lymph node sampling in pancreatic head adenocarcinoma

BACKGROUND

The significance of positive para-aortic nodes in patients with resectable pancreatic carcinoma is unclear. This study sought to evaluate the accuracy of intraoperative detection and prognostic significance of these lymph nodes in patients with resected adenocarcinoma of the pancreatic head.

METHODS

From 2000 to 2010, para-aortic node sampling was performed prospectively in all patients before pancreatoduodenectomy. Frozen sections were created and nodes categorized as positive or negative for metastases. Surgeons were blinded to the frozen-section results. This was followed by standard histopathological assessment of corresponding paraffin-embedded, haematoxylin and eosin-stained material. Nodes considered uninvolved by this analysis were examined immunohistochemically for micrometastases.

RESULTS

A total of 111 consecutive patients were included, with a median follow-up of 20·8 (range 1·5-126) months. The 1-, 2- and 5-year overall survival (OS) and disease-free survival (DFS) rates were 73·6, 54·0 and 24·7 per cent, and 51·8, 28·1 and 18·8 per cent respectively. Para-aortic node involvement was always associated with peripancreatic lymph node metastasis, and was detected by frozen-section analysis in 12 patients and by haematoxylin and eosin staining in 17. Sensitivity and specificity of frozen-section examination for detecting para-aortic lymph node metastases were 71 and 100 per cent respectively. Median OS for patients with and without para-aortic node involvement on frozen-section analysis was 9·7 versus 28·5 months respectively (P = 0·012), and 15·7 versus 27·2 months (P = 0·050) when assessed by haematoxylin and eosin staining. Median DFS for patients with and without para-aortic node involvement on frozen-section examination was 5·6 versus 12·9 months respectively (P = 0·041), and 8·4 versus 12·9 months (P = 0·038) for haematoxylin and eosin analysis. The presence of micrometastases in para-aortic nodes was not significantly associated with altered OS or DFS.

CONCLUSION

Para-aortic node sampling with frozen-section examination detects distant lymphatic involvement reliably. It should be performed systematically. When metastases are found, they should be considered a contraindication to pancreatic resection.

Small bowel adenocarcinoma phenotyping, a clinicobiological prognostic study

BACKGROUND

Small bowel adenocarcinoma (SBA) is a rare tumour with a poor prognosis. Molecular biology data on SBA carcinogenesis are lacking.

METHODS

Expression of HER2, β-catenin, p53 and mismatch repair (MMR) protein was assessed by immunohistochemistry. KRAS, V600E BRAF mutations and microsatellite instability were investigated.

RESULTS

We obtained samples from 63 SBA patients (tumour stages: I-II: 30%; III: 35%; IV: 32%; locally advanced: 3%). HER2 overexpression (3+) was observed in 2 out of 62 patients, overexpression of p53 in 26 out of 62, abnormal expression of β-catenin in 12 out of 61, KRAS mutation in 21 out of 49, BRAF V600E mutation in 1 out of 40 patients, MMR deficiency (dMMR) in 14 out of 61 and was consistent with Lynch syndrome in 9 out of 14 patients. All of the dMMR tumours were in the duodenum or jejunum and only one was stage IV. Median overall survival (OS) was 36.6 months (95% CI, 26.9-72.2). For all patients, in univariate analysis, stages I-II (P<0.001), WHO PS 0-1 (P=0.01) and dMMR phenotype (P=0.02) were significantly associated with longer OS. In multivariate analysis, disease stage (P=0.01) and WHO PS 0-1 (P=0.001) independently predicted longer OS. For stage IV patients, median OS was 20.5 months (95% CI: 14.6; 36.6 months). In multivariate analysis, WHO PS 0-1 (P=0.0001) and mutated KRAS status (P=0.02) independently predicted longer OS.

CONCLUSION

This large study suggests that molecular alterations in SBA are closer to those in colorectal cancer (CRC) than those in gastric cancer, with low levels of HER 2 overexpression and high frequencies of KRAS mutations. The seemingly higher frequency of dMMR than in CRC may be explained by the higher frequency of Lynch syndrome in SBA patients. A dMMR phenotype was significantly associated with a non-metastatic tumour (P=0.02). A trend for a good prognosis and a duodenum or jejunum primary site was associated with dMMR.

Number of examined lymph nodes and nodal status assessment in pancreaticoduodenectomy for pancreatic adenocarcinoma

BACKGROUND

The accuracy of the assessment of the nodal status in resected cephalic pancreatic adenocarcinoma (PA) depends on the number of examined lymph nodes (NELN). This study assesses the impact of the NELN on N staging and survival and propose a minimal number of examined lymph nodes (MNELN) ensuring reliability of the pN status determination.

METHODS

188 consecutive patients treated by pancreaticoduodenectomy (PD) for PA. Correlations between NELN and survivals of pN0 and pN1 groups and with the rate of pN1 patients were studied. A probability model based on the binomial law was built to estimate the MNELN able to detect pN1 patients with a sensitivity ≥ 95%.

RESULTS

Overall and disease free 5-year survivals were 27.2% and 24.6% respectively. 135 patients (71.8%) were staged pN1. The median NELN was 17 (range 0-68). Overall and disease free survivals of pN1 patients were not related to NELN. The influence of NELN on survival in pN0 patients due to stage migration did not reach significance. The probability model showed that a MNELN of 16 nodes was required to detect pN1 patients with a sensitivity of 95%.

CONCLUSION

A MNELN of 16 is required to assess pN status and should be considered as a quality criterion in future studies and trials on PD for PA.

Contribution of CXCR4 and SMAD4 in predicting disease progression pattern and benefit from adjuvant chemotherapy in resected pancreatic adenocarcinoma

BACKGROUND

Prognosis of patients with pancreatic adenocarcinoma is poor. Many prognostic biomarkers have been tested, but most studies included heterogeneous patients. We aimed to investigate the prognostic and/or predictive values of four relevant biomarkers in a multicentric cohort of patients.

PATIENTS AND METHODS

A total of 471 patients who had resected pancreatic adenocarcinoma were included. Using tissue microarray, we assessed the relationship of biomarker expressions with the overall survival: Smad4, type II TGF-β receptor, CXCR4, and LKB1.

RESULTS

High CXCR4 expression was found to be the only independent negative prognostic biomarker [hazard ratio (HR) = 1.74; P < 0.0001]. In addition, it was significantly associated with a distant relapse pattern (HR = 2.19; P < 0.0001) and was the strongest prognostic factor compared with clinicopathological factors. In patients who did not received adjuvant treatment, there was a trend toward decrease in the overall survival for negative Smad4 expression. Loss of Smad4 expression was not correlated with recurrence pattern but was shown to be predictive for adjuvant chemotherapy (CT) benefit (HR = 0.59; P = 0.002).

CONCLUSIONS

CXCR4 is a strong independent prognostic biomarker associated with distant metastatic recurrence and appears as an attractive target to be evaluated in pancreatic adenocarcinoma. Negative SMAD4 expression should be considered as a potential predictor of adjuvant CT benefit.

Unexplained polyposis: a challenge for geneticists, pathologists and gastroenterologists

Two main colorectal polyposis syndromes have been described, familial adenomatous polyposis and MUTYH-associated polyposis syndromes. Some polyposis remains unexplained: 20% of adenomatous polyposis and serrated polyposis. The aim of this study was to evaluate in a cohort of patients with unexplained polyposis whether a genetic defect could be detected. Individuals presenting polyposis with more than 40 adenomas or more than 20 serrated polyps (hyperplastic, sessile serrated and mixed), without causative mutation identified, were included. Complementary explorations on APC or MUTYH were performed: search for APC mosaicism, splicing-affecting mutations, large genomic rearrangement of MUTYH. Four genes of Wnt pathway (AXIN2, PPP2R1B, WIF1, SFRP1) and two genes of transforming growth factor-β (TGF-β) pathway (SMAD4, BMPR1A) were screened for germline mutation. Twenty-five patients had an unexplained adenomatous polyposis (familial or sporadic). Five pathogenic mutations were found: four in APC gene (with one case of mosaicism) and one in BMPR1A gene. The exploration of APC mosaicism was better performed from adenoma DNA with high-resolution melting. The screening of the candidate genes did not find any causative mutation. Thirteen individuals had an unexplained serrated polyposis and a frameshift on SMAD4 gene was identified. All mutations were identified in familial cases of polyposis. After new pathological examination, both BMPR1A and SMAD4 cases were found to be associated with a juvenile polyposis while the polyposis was initially described as adenomatous or undetermined. In 17% (6/38) of the patients the causative mutation of the polyposis was identified. Genetic causes were heterogeneous. Sporadic polyposis patients must be considered as potential APC mosaicism. The histological classification of polyposis is strongly important in direct genetic exploration.

Colorectal neoplasia in Crohn's colitis: a retrospective comparative study with ulcerative colitis

AIMS

To determine the clinicopathological features of colorectal cancer (CRC) in Crohn's disease (CD).

METHODS AND RESULTS

All histological slides from surgical specimens with inflammatory bowel disease-related colorectal neoplasia examined in our hospital between 1990 and 2005 were reviewed. We identified 18 CRCs in 16 patients with CD and compared them with 57 CRCs in 41 patients with ulcerative colitis (UC). We also studied 25 patients with dysplasia without cancer (CD 2, UC 23). When CD and UC were compared, the median age at diagnosis of cancer (CD 52 years, UC 51 years), the frequency of mucinous adenocarcinoma (CD 16.7%, UC 17.5%) and the frequency of dysplasia adjacent to and distal from cancer (CD 56.3 and 37.5%, UC 65.8 and 39%, respectively) were similar. All neoplastic lesions occurred in areas affected by inflammatory bowel disease.

CONCLUSIONS

CRC complicating CD and UC shares many clinicopathological features, in particular similar frequencies of dysplasia, both adjacent and distal, with cancer. Thus, surveillance for patients with Crohn's colitis should be similar to that for patients with UC. Consideration should be given to a more extensive UC-like surgical approach instead of segmental resection of the involved area.

Barrett's oesophagus?a pathologist's view

Barrett's oesophagus, a precancerous condition for oesophageal adenocarcinoma, detected on endoscopy and confirmed on histology, shows intestinal metaplasia of the lower oesophagus. The significance of microscopic foci of intestinal metaplasia at the gastro-oesophageal junction, corresponding either to so-called 'ultrashort' segment Barrett's oesophagus, or to carditis with intestinal metaplasia, is still a matter of debate. The surveillance of patients with Barrett's oesophagus is still based on systematic biopsy sampling of Barrett's mucosa on endoscopy, looking for dysplasia. Although well-established classifications of dysplasia are now used by most pathologists, there remain numerous problems with this subjective marker (sampling, diagnostic reproducibility, natural history, etc). Therefore, many alternative biomarkers have been proposed, but only DNA aneuploidy, proliferation markers and p53 loss of heterozygosity/overexpression have been shown to be of some use at the present time. Some endoscopic improvements already allow a better selection of biopsies, and it may be that in future new technologies will allow 'virtual biopsies'. On the other hand, the role of pathologists now extends to the evaluation of new therapeutic modalities of early neoplastic lesions in Barrett's oesophagus, especially endoscopic mucosal resection.

Ciliated hepatic foregut cyst with extensive squamous metaplasia: report of a case

Ciliated hepatic foregut cysts (CHFC) are rare cystic lesions of the liver composed of a ciliated pseudostratified columnar epithelium with mucous cells, connective tissue, and smooth muscles bundles. We report the first case of CHFC with extensive squamous metaplasia without dysplasia or carcinoma. A unilocular, avascular, hypoechoic 60-mm liver lesion located in segment IV was detected by ultrasonography in a 31-year-old woman. The cyst was surgically removed and was lined mainly by a regular squamous epithelium without keratin formation. After extensive sampling, a ciliated pseudostratified columnar epithelium with some alcian blue-positive goblet cells was identified. The lesion was totally examined and there was no epithelial dysplasia or carcinoma. Squamous epithelium is very rare in hepatic foregut cysts and may degenerate into squamous carcinoma. Squamous epithelium is also described in biliary cysts. When squamous epithelium is identified in a liver cyst, an extensive sampling is recommended to identify possible foci of squamous carcinoma and to classify more precisely the histological type of the lesion. Because some cases of squamous carcinoma have been described in CHFC, surgical removal of the lesion may be more appropriate than close follow-up or sclerosing therapy.

Genome-wide expression profiling and tissue array analysis for prediction of recurrences in stage II-III colorectal cancer (CRC)

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Background: Despite substantial progress in molecular pathogenesis of colon cancer (CC), no reliable biomarkers of outcome have yet been identified in patients with resected stage II-III CC. Methods: We analyzed genome-wide mRNA expression profiles in 20 stage II or III left side CC from 10 patient who developed metastasis (M+) and 10 disease free patients followed up for at least 4 years (M-) using high-density oligonucleotide microarrays (Agilent technology). RNA from tumor tissue (T) was hybridized against normal tissue (NT) from the same patient and each experiment was replicated 4 times (with 2 dye-swaps). The goal was to select genes both differentially expressed between T and NT and between M+ and M-. A tissu-array was constructed using 212 stage II and III resected CRC (164 CC, 64 rectal cancers) and their matched NT. For survival analysis, immunohistochemistry (IHC) data was dichotomized at the median value. Results: Analysis of microarray data yielded 27 genes that had a 2-fold difference between the expression in T and NT in at least 5 out of 20 patients and for which the average expression was significantly different between M+ and M- (p<0.01, t-test). Among the 6 most differentially expressed genes between M+ and M- in T, 4 of them were found to be involved in interferon γ pathway and could be evaluated by IHC: CXCL9, CXCL13, PPARγ, THSD. In order to assess macrophage and natural killer (NK) cell infiltration, CD68 and CD57 were also analyzed. Intensity was measured by semi-quantitative scores for the first 4 genes and by the number of infiltrating cells for the others. CXCL9, PPARGγ, CXCL13, CD57 and CD68 were significantly underexpressed in T as compared to NT (p<0.0001, paired t-test). The logrank test stratified by cancer site indicated that high IHC expression of CD57 possessed a significantly better recurrence-free survival (RFS) than those low expression (p=0.004). Multivariate Cox analysis identified tumor site (p=0.001), node stage (p<0.001) and CD57 (p=0.002) as independent predictors of RFS. Conclusions: NK cell infiltration within colorectal cancers is associated with prolonged recurrence-free survival in stage II and III CRC.

No significant financial relationships to disclose.

Immunohistochemical analysis of adenocarcinoma of the small intestine: a tissue microarray study

BACKGROUND

Primary adenocarcinomas of the small intestine are rare, and the genetic mechanisms involved in their carcinogenesis remain unclear.

AIM

To examine the expression of candidate proteins in small intestinal adenocarcinomas by immunohistochemistry performed on tissue microarrays (TMAs).

METHODS

Twenty seven primary sporadic small intestinal adenocarcinomas were analysed. The TMA technique was validated by comparing immunohistochemical labelling of hMLH1 and hMSH2 on TMAs and the tissue sections they derived from. The expression of Smad4, hMSH6, beta catenin, and p53 was investigated and results compared with those obtained in 14 malignant ampullary tumours.

RESULTS

TMA technology with threefold redundancy adequately represented the immunohistochemical pattern of small intestinal adenocarcinomas. Loss of hMLH1 expression, but not hMSH2 or hMSH6, was seen in two of 27 small intestinal adenocarcinomas. All ampullary tumours showed nuclear staining for hMSH2 and hMSH6. One case showed lack of immunostaining for hMLH1. Smad4 expression was absent in five small intestinal adenocarcinomas and two ampullary tumours. Overexpression of p53 was detected in the nuclei of 14 of the 27 small intestinal adenocarcinomas, and five of the 14 ampullary tumours. Nuclear or cytoplasmic expression of beta catenin was present in all specimens.

CONCLUSION

Inactivation of the SMAD4/DPC4 gene seems to be involved in small intestinal adenocarcinoma tumorigenesis. Overexpression of p53 and abnormal expression of beta catenin are two common events, unlike the loss of expression of the DNA mismatch repair proteins (hMLH1, hMSH2, and hMSH6). The carcinogenetic process appears to be similar in small intestinal adenocarcinomas and malignant ampullary tumours.