Molecular predictive markers in tumors of the gastrointestinal tract

Gastric Carcinomas With Lymphoid Stroma: An Evaluation of the Histopathologic and Molecular Features

Gastric carcinoma with lymphoid stroma is an uncommon variant enriched for mutually exclusive Epstein-Barr virus (EBV) positivity and mismatch repair (MMR) deficiency. We performed this study to evaluate molecular alterations in this morphologically homogeneous subtype and compare them with 295 conventional gastric cancers analyzed in The Cancer Genome Atlas study. We identified 31 study cases and subjected them to in situ hybridization for EBV-encoded RNAs and assessment for MMR status. Immunostains for PD-L1, β-catenin, and HER2 were performed; extracted DNA was sequenced with a Comprehensive Cancer Panel. Most study patients were older adult men with stage I or II disease (76%). Tumors were classified as EBV/MMR-proficient (MMR-P) (n=7), EBV/MMR deficient (n=12), and EBV/MMR-P (n=12). EBV/MMR-P tumors were usually located in the proximal stomach (83%) and showed heterogenous growth patterns with glandular differentiation (83%). Tumors in all groups showed numerous tumor infiltrating lymphocytes and PD-L1 expression, infrequent nuclear β-catenin accumulation (10%), and lacked both membranous HER2 staining and HER2 amplification. EBV/MMR-deficient tumors showed significantly higher tumor mutation burden (P=0.001) and KRAS alterations (56%) compared with EBV/MMR-P tumors (9%, P=0.05). TP53 variants were more common among EBV/MMR-P tumors (82%) compared with EBV/MMR proficient (0%, P=0.01) and EBV/MMR-deficient (11%, P<0.01) tumors. Alterations in KRAS, ARID1A, PIK3CA, and TP53 followed similar patterns of distribution compared with The Cancer Genome Atlas dataset. We conclude that gastric carcinomas with lymphoid stroma show a spectrum of molecular changes and frequent PD-L1 expression, raising the possibility that this subgroup of tumors may be susceptible to checkpoint inhibitors and/or agents that target receptor tyrosine kinase-mediated signaling.

Somatic alterations in circulating cell-free DNA of oesophageal carcinoma patients during primary staging are indicative for post-surgical tumour recurrence

Oesophageal cancer (OC) has high mortality. This study aims at determining the feasibility of liquid biopsies for genomic profiling in early stage OC, comparing two different technologies for mutational analysis in circulating cell -free DNA (ccfDNA) and evaluating the clinical impact of these somatic alterations during primary staging. In 25 patients with locally advanced OC, endoscopic tumour biopsies and simultaneous blood samples were taken during primary staging. Genomic DNA from biopsies and ccfDNA were analysed for mutations using a 12 gene panel next-generation sequencing (NGS) assay as well as digital droplet PCR (ddPCR). Genetic data was correlated with patients' outcome. In 21 of the tested biopsies (84%) at least one somatic mutation was detected by NGS. Mutations detected by NGS were detectable by ddPCR with similar allele frequencies. In three out of the 21 patients with proven mutations, the same mutations were also detectable in ccfDNA using NGS (14%). In contrast, ddPCR detected mutations in ccfDNA of five additional patients (8/21, 38%). Post-surgical outcome analysis was performed for those patients who had received complete tumour resection (n = 16). Five of them suffered from an early relapse within the first year after surgery, including four with detectable somatic mutations in ccfDNA during primary staging. Taken together, we showed a higher sensitivity for ddPCR compared to NGS in detecting mutated ccfDNA in OC. Detection of somatically altered ccfDNA during primary staging seems to be indicative for post-surgical tumour recurrence.

New Development of Biomarkers for Gastrointestinal Cancers: From Neoplastic Cells to Tumor Microenvironment

Biomarkers refer to a plethora of biological characteristics that can be quantified to facilitate cancer diagnosis, forecast the prognosis of disease, and predict a response to treatment. The identification of objective biomarkers is among the most crucial steps in the realization of individualized cancer care. Several tumor biomarkers for gastrointestinal malignancies have been applied in the clinical setting to help differentiate between cancer and other conditions, facilitate patient selection for targeted therapies, and to monitor treatment response and recurrence. With the coming of the immunotherapy age, the need for a new development of biomarkers that are indicative of the immune response to tumors are unprecedentedly urgent. Biomarkers from the tumor microenvironment, tumor genome, and signatures from liquid biopsies have been explored, but the majority have shown a limited prognostic or predictive value as single biomarkers. Nevertheless, use of multiplex biomarkers has the potential to provide a significantly increased diagnostic accuracy compared to traditional single biomarker. A comprehensive analysis of immune-biomarkers is needed to reveal the dynamic and multifaceted anti-tumor immunity and thus imply for the rational design of assays and combinational strategies.

Krukenberg tumors: Seed, route and soil

The aim of this narrative review was to summarize the current evidence on Krukenberg tumors (KTs), addressing what is known on their natural history and their impact on the clinical prognosis and which are the most appropriate management strategies to treat this condition. A literature search was conducted on Pubmed up to December 2016, selecting the most relevant studies on the basis of the scope of the review. KTs are ovarian metastases from primary signet-ring cell carcinomas., characterized by the presence of a sarcoma-like stroma. They have three possible routes of diffusion (lymphatic, peritoneal and hematogenous), but the preferential one is still unclear. Prognosis is dismal. When KTs are encountered in the clinical practice, it is reasonable to offer surgical resection to young, fit patients with limited disease. Palliative surgery should be considered for all patients with symptomatic disease. Further studies should clarify the clinicopathologic characteristics of KTs, their main routes of diffusion, and the possible role of prophylactic oophorectomy, lymphadenectomy and intraperitoneal chemotherapy. Molecular and transitional research should parallel the clinical one to help understanding the natural history of signet-ring cell carcinomas.

Acyclonucleosides bearing coplanar arylethynyltriazole nucleobases: synthesis, structural analysis, and biological evaluation

The efficient synthesis of acyclonucleosides bearing coplanar 3-arylethynyltriazole motifs was established and several compounds displayed antiproliferative activity against cancer cells.