Gastric Carcinoma in Autoimmune Gastritis: A Histopathologic and Molecular Study.

Patients with autoimmune gastritis (AIG) have a 13-fold risk of developing type-1 neuroendocrine tumors, whereas the risk for gastric adenocarcinoma is still uncertain. Here we describe the clinicopathologic and molecular features of a series of gastric carcinomas (GC) arising in the context of AIG. A total of 26 AIG-associated GC specimens were collected from 4 Italian Institutions. Immunohistochemistry for MUC1, MUC2, MUC5AC, MUC6, CDX2, HER2, PD-L1, CLDN18, mismatch repair (MMR) proteins, and p53 and EBV-encoded RNA (EBER) in situ hybridization were performed. Histologic and immunohistochemical features were jointly reviewed by 5 expert gastrointestinal pathologists. Next-generation sequencing analysis (TrueSight Oncology 500, Illumina) of 523 cancer-related genes was performed on 19 cases. Most tumors were diagnosed as pT1 (52%) and they were located in the corpus/fundus (58%) and associated with operative link for gastritis assessment stage II gastritis (80.8%), absence of parietal cells, complete intestinal metaplasia, and enterochromaffin-like-cell micronodular hyperplasia. Only 4 (15.4%) GCs were diagnosed during follow-up for AIG. The following histotypes were identified: 20 (77%) adenocarcinomas; 3 (11%) mixed neuroendocrine-non-neuroendocrine neoplasms, and 2 (8%) high-grade solid adenocarcinomas with focal neuroendocrine component, 1 (4%) adenocarcinoma with an amphicrine component. Overall, 7 cases (27%) showed MMR deficiency, 3 (12%) were positive (score 3+) for HER2, 6 (23%) were CLDN18 positive, and 11 (42%) had PD-L1 combined positive score ≥ 10. EBER was negative in all cases. Molecular analysis revealed 5/19 (26%) microsatellite instability (MSI) cases and 7 (37%) tumor mutational burden (TMB) high. The most frequently altered genes were TP53 (8/19, 42%), RNF43 (7/19, 37%), ERBB2 (7/19, 37% [2 amplified and 5 mutated cases]), ARID1A (6/19, 32%), and PIK3CA (4/19, 21%). In summary, AIG-associated GCs are often diagnosed at low stage in patients with longstanding misrecognized severe AIG; they often display a neuroendocrine component or differentiation, have relatively higher rates of MMR deficiency, and TMB high.

IMMUNOREACT 7: Regular aspirin use is associated with immune surveillance activation in colorectal cancer.

BACKGROUND: Long-term daily use of aspirin reduces incidence and mortality due to colorectal cancer (CRC). This study aimed to analyze the effect of aspirin on the tumor microenvironment, systemic immunity, and on the healthy mucosa surrounding cancer. METHODS: Patients with a diagnosis of CRC operated on from 2015 to 2019 were retrospectively analyzed (METACCRE cohort). Expression of mRNA of immune surveillance-related genes (PD-L1, CD80, CD86, HLA I, and HLA II) in CRC primary cells treated with aspirin were extracted from Gene Expression Omnibus-deposited public database (GSE76583). The experiment was replicated in cell lines. The mucosal immune microenvironment of a subgroup of patients participating in the IMMUNOREACT1 (ClinicalTrials.gov NCT04915326) project was analyzed with immunohistochemistry and flow cytometry. RESULTS: In the METACCRE Cohort, 12% of 238 patients analyzed were aspirin users. Nodal metastasis was significantly less frequent (p = .008) and tumor-infiltrating lymphocyte infiltration was higher (p = .02) among aspirin users. In the CRC primary cells and selected cell lines, CD80 mRNA expression was increased following aspirin treatment (p = .001). In the healthy mucosa surrounding rectal cancer, the ratio of CD8/CD3 and epithelial cells expressing CD80 was higher in aspirin users (p = .027 and p = .034, respectively). CONCLUSIONS: These data suggested that regular aspirin use may have an active role in enhancing immunosurveillance against CRC.

HER2 expression and genOmic characterization of rESected brain metastases from colorectal cancer: the HEROES study.

BACKGROUND: Little is known about prognostic factors of brain metastases (BM) from colorectal cancer (CRC). HER2 amplification/overexpression (HER2+) was previously described; its impact on prognosis remains uncertain. METHODS: In the translational study HEROES, extensive molecular analysis was performed on primary CRC (prCRC) and their matched resected BM by means of NGS comprehensive genomic profiling and HER2 status as assessed by immunohistochemical/ in situ hybridization. Count of tumour-infiltrating lymphocytes (TILs) was also performed. PRIMARY OBJECTIVE: to describe the molecular landscape of paired BM/prCRC. SECONDARY OBJECTIVES: to search for new prognostic biomarkers of outcome after BM resection: intracranial-only Progression-Free Survival (BM-iPFS), Progression-Free Survival (BM-PFS), and Overall Survival (BM-OS). RESULTS: Out of 22 patients having paired samples of prCRC and BM, HER2+ was found on 4 (18%) BM, 3 (75%) of which also HER2+ in matched prCRC. Lower tumour mutation burden (HR 3.08; 95%CI 1.06-8.93; p = 0.0386) and HER2-negative BM (HER2neg) (HR 7.75;95%CI 1.97-30.40; p = 0.0033) were associated with longer BM-iPFS; HER2neg BM (HR 3.44; 95%CI 1.03-11.53; p = 0.0449) and KRASmut BM (HR 0.31; 95%CI 0.12-0.80; p = 0.0153) conferred longer BM-PFS. Longer BM-OS was found in pts with TILs-enriched (≥1.6/HPF) BM (HR 0.11; 95%CI0.01-0.91; p = 0.0403). CONCLUSIONS: This study shows HER2+ enrichment in both BM and their prCRC. TILs-enriched BM conferred better BM-OS.