Magali Svrcek

Expression of a mutant HSP110 sensitizes colorectal cancer cells to chemotherapy and improves disease prognosis.

Heat shock proteins (HSPs) are necessary for cancer cell survival. We identified a mutant of HSP110 (HSP110ΔE9) in colorectal cancer showing microsatellite instability (MSI CRC), generated from an aberrantly spliced mRNA and lacking the HSP110 substrate-binding domain. This mutant was expressed at variable levels in almost all MSI CRC cell lines and primary tumors tested. HSP110ΔE9 impaired both the normal cellular localization of HSP110 and its interaction with other HSPs, thus abrogating the chaperone activity and antiapoptotic function of HSP110 in a dominant-negative manner. HSP110ΔE9 overexpression caused the sensitization of cells to anticancer agents such as oxaliplatin and 5-fluorouracil, which are routinely prescribed in the adjuvant treatment of people with CRC. The survival and response to chemotherapy of subjects with MSI CRCs was associated with the tumor expression level of HSP110ΔE9. HSP110 may thus constitute a major determinant for both prognosis and treatment response in CRC.

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.

Diagnosis of Constitutional Mismatch Repair-Deficiency Syndrome Based on Microsatellite Instability and Lymphocyte Tolerance to Methylating Agents

BACKGROUND & AIMS Patients with bi-allelic germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, or PMS2) develop a rare but severe variant of Lynch syndrome called constitutional MMR deficiency (CMMRD). This syndrome is characterized by early-onset colorectal cancers, lymphomas or leukemias, and brain tumors. There is no satisfactory method for diagnosis of CMMRD because screens for mutations in MMR genes are noninformative for 30% of patients. MMR-deficient cancer cells are resistant to genotoxic agents and have microsatellite instability (MSI), due to accumulation of errors in repetitive DNA sequences. We investigated whether these features could be used to identify patients with CMMRD. METHODS We examined MSI by PCR analysis and tolerance to methylating or thiopurine agents (functional characteristics of MMR-deficient tumor cells) in lymphoblastoid cells (LCs) from 3 patients with CMMRD and 5 individuals with MMR-proficient LCs (controls). Using these assays, we defined experimental parameters that allowed discrimination of a series of 14 patients with CMMRD from 52 controls (training set). We then used the same parameters to assess 23 patients with clinical but not genetic features of CMMRD. RESULTS In the training set, we identified parameters, based on MSI and LC tolerance to methylation, that detected patients with CMMRD vs controls with 100% sensitivity and 100% specificity. Among 23 patients suspected of having CMMRD, 6 had MSI and LC tolerance to methylation (CMMRD highly probable), 15 had neither MSI nor LC tolerance to methylation (unlikely to have CMMRD), and 2 were considered doubtful for CMMRD based on having only 1 of the 2 features. CONCLUSION The presence of MSI and tolerance to methylation in LCs identified patients with CMMRD with 100% sensitivity and specificity. These features could be used in diagnosis of patients.

Lynch or Not Lynch? Is that Always a Question?

The familial cancer syndrome referred to as Lynch I and II was renamed hereditary nonpolyposis colorectal cancer (HNPCC) only to revert later to Lynch syndrome (LS). LS is the most frequent human predisposition for the development of colorectal cancer (CRC), and probably also for endometrial and gastric cancers, although it has yet to acquire a consensus name. Its estimated prevalence ranges widely from 2% to 7% of all CRCs due to the fact that tumors from patients with LS are difficult to recognize at both the clinical and molecular level. This review is based on two assumptions. First, all LS patients inherit a predisposition to develop CRC (without polyposis) and/or other tumors from the Lynch spectrum. Second, all LS patients have a germline defect in one of the DNA mismatch repair (MMR) genes. When a somatic second hit inactivates the relevant MMR gene, the consequence is instability of DNA repeat sequences such as microsatellites and the tumors are referred to as having the microsatellite instability (MSI) phenotype. However, some of the inherited predisposition to develop CRC without concurrent polyposis, termed HNPCC, is found in non-LS patients, while not all MSI tumors are from LS cases. LS tumors are therefore at the junction of inherited and MSI cases. We describe here the defining characteristics of LS tumors that differentiate them from inherited non-MSI tumors and from non-inherited MSI tumors.

Immunotherapy and patients treated for cancer with microsatellite instability

Microsatellite instability (MSI) is a tumor phenotype linked to somatic or germline (Lynch syndrome) inactivating alterations of DNA mismatch repair genes. A broad spectrum of neoplasms exhibits MSI phenotype, mainly colorectal cancer, endometrial cancer, and gastric cancer. MSI tumors are characterized by dense immune infiltration and high load of tumor neo-antigens. Growing evidence is accumulating on the efficacy of immune checkpoint inhibition for patients treated for MSI solid tumors. We present a comprehensive overview of MSI phenotype, its biological landscape and current diagnostic methods. Then we focus on MSI as a predictive biomarker of response to immune checkpoint inhibition in the context of colorectal cancer and non-colorectal tumors.

Expression of epidermal growth factor receptor (EGFR) is frequent in inflammatory bowel disease (IBD)-associated intestinal cancer

Sir, Epidermal growth factor receptor (EGFR), which is part of the human epidermal receptor family of tyrosine kinase receptors, is expressed by a variety of cells, including normal and tumoural epithelial cells of the gastrointestinal tract [3]. EGFR appears to be a key element in colorectal carcinogenesis. Its activation induces cellular growth, cell differentiation, proliferation and migration. EGFR expression is present in approximately 60–80% of sporadic colorectal cancer (CRC) [5]. EGFR inhibitors, such as monoclonal antibodies or small molecules inhibiting tyrosine kinase activity, have been developed and several clinical trials have demonstrated their efficacy in patients with advanced CRC [4]. Patients with inflammatory bowel disease (IBD) face an increased risk of CRC in ulcerative colitis (UC) and Crohn’s disease (CD), and of small intestinal cancer (SIC) in CD. The molecular events underlying IBDassociated CRC seem to be different from sporadic CRC. Only a few studies have assessed the expression of EGFR in IBD-associated intestinal neoplasms [1]. We studied 7 SIC and 16 CRC in patients with CD and 49 CRC in patients with UC. The specimens, obtained from surgical resections between 1990 and 2004, were selected from the files of the Pathology Department of SaintAntoine Hospital, AP-HP, Paris, France. Immunohistochemical study of EGFR expression was also performed on dysplastic lesions (n=10) and lymph node metastases (n=2). Immunohistochemical staining was carried out with the EGFR pharmDx kit (DakoCytomation, Trappes, France), used according to the manufacturer’s instructions. Only complete or incomplete membranous staining of tumoural cells was considered as positive. EGFR expression was assessed according to both the percentage of reactive tumour cells and the mean intensity of the membranous staining (1+, weak reactivity; 2+, moderate reactivity and 3+, strong reactivity). EGFR reactivity in the region of deepest tumour invasion was also assessed. Positive immunohistochemical staining of any intensity was detected in all SIC, in 13/16 (81%) CRC in patients with CD and in 43/49 (88%) CRC in patients with UC. Four SIC (57%) and eight CRC (50%) in patients with CD and seven CRC in patients with UC (24%) had 2+ or 3+ EGFR reactivity in more than 50% of the cells. In more than half of the cases, neoplastic cells were stained with a greater intensity in the region of deepest tumour invasion, Virchows Arch (2007) 450:243–244 DOI 10.1007/s00428-006-0338-7

ERBB3-Activating Mutations in Small Bowel Adenocarcinomas

PurposeFunctional studies have demonstrated that some mutations of ERBB3, which encodes for human epidermal growth factor receptor (HER) 3, are oncogenic via activation of the ErbB family signaling pathway. Significant clinical activity of anti-HER2 therapies (trastuzumab plus lapatinib combination or afatinib) has been reported in patients with ERBB3-mutated cancers. This study was designed to report the rate of activating ERBB3 mutations in small bowel adenocarcinoma (SBA), a rare tumor type in which we previously reported a high rate (12%) of ERBB2-activating mutations.Materials and MethodsDNA from 74 SBAs, previously characterized for ERBB2 mutations and mismatch repair status, was submitted for sequencing of ERBB3 exons 3, 6, 7, 8, and 23. Orthogonal validation by targeted next-generation sequencing was performed.ResultsFour of 74 SBAs (5.4%) displayed ERBB3-activating mutations, including three p.V104M mutations (c.310 G>A) in exon 3 and one p.E928G mutation (c.2783 A>G) in exon 23. No mutations wer...

Les lésions colorectales festonnées : quelle signification pour le pathologiste, le gastroentérologue et le patient ?

Environ 30 % des cancers colorectaux (CCR) se developpent a partir de lesions festonnees. Les lesions festonnees constituent un groupe heterogene, caracterise, d’un point de vue moleculaire, par une mutation frequente et precoce de BRAF et un phenotype CIMP. La derniere classification de l’OMS (2010) individualise 3 types de lesions festonnees : i) les polypes hyperplasiques ; ii) les adenomes/polypes sessiles festonnes (A/P SF), avec ou sans dysplasie ; iii) les adenomes festonnes traditionnels (AFT). Le potentiel malin des A/P SF et des AFT est maintenant clairement etabli. Ces lesions, en particulier les A/P SF, sont encore sous-diagnostiquees par les pathologistes, notamment en raison d’un manque de standardisation et de l’evolution de leurs criteres diagnostiques. Les A/P SF peuvent etre difficiles a diagnostiquer en endoscopie et pourraient etre responsables d’un certain nombre de cancers d’intervalle du colon droit. A l’heure actuelle, les recommandations de prise en charge de ces lesions sont proches de celles des adenomes « conventionnels », en depit de faibles niveaux de preuve. Une meilleure connaissance des lesions festonnees d’un point de vue a la fois clinique, anatomo-pathologique et moleculaire permettra de mieux les diagnostiquer et de mieux prendre en charge les patients.

Statuts MMR et BRAF dans les cancers colorectaux : intérêts pour la prise en charge thérapeutique ?

Colorectal cancer (CRC) is the second leading cause of cancer-related mortality in France. Recently, colorectal cancer subtyping consortium (CRCSC) identified 4 consensus molecular subtypes (CMS). CMS1 is enriched for CRC with deficient DNA mismatch repair system (dMMR) and tumors with mutated BRAF. Intriguingly, CMS1 is characterized by better relapse-free survival but worse survival after relapse, compared with the other subtypes. In this review, we provide a comprehensive overview of prognostic and predictive impacts of MMR and BRAF status. We highlight immune checkpoints inhibitors as potentially future therapeutics for CRC with deficient MMR. We also focus on the management of BRAF mutant metastatic CRC, with a particular interest on targeted therapies.