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 clinicopathological 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 four Italian Institutions. Immunohistochemistry for MUC1, MUC2, MUC5AC, MUC6, CDX2, HER2, PD-L1, CLDN18, Mismatch Repair (MMR) proteins, and p53 and EBER in situ hybridization were performed. Histologic features and IHC were jointly reviewed by five 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%), were located in the corpus/fundus (58%) and were associated with OLGA stage II gastritis (80.8%), absence of parietal cells, complete intestinal metaplasia and ECL-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%) MSI cases and 7 (37%) TMB-high. The most frequently altered genes were: TP53 (8/19, 42%), RNF43 (7/19, 37%), ERBB2 (7/19, 37% [two amplified and five 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 long-standing misrecognized severe AIG; they often display a neuroendocrine component or differentiation, have relatively higher rates of MMR deficiency, and TMB-high.

Digital counting of tissue cells for molecular analysis: the QuANTUM pipeline.

The estimation of tumor cellular fraction (TCF) is a crucial step in predictive molecular pathology, representing an entry adequacy criterion also in the next-generation sequencing (NGS) era. However, heterogeneity of quantification practices and inter-pathologist variability hamper the robustness of its evaluation, stressing the need for more reliable results. Here, 121 routine histological samples from non-small cell lung cancer (NSCLC) cases with complete NGS profiling were used to evaluate TCF interobserver variability among three different pathologists (pTCF), developing a computational tool (cTCF) and assessing its reliability vs ground truth (GT) tumor cellularity and potential impact on the final molecular results. Inter-pathologist reproducibility was fair to good, with overall Wk ranging between 0.46 and 0.83 (avg. 0.59). The obtained cTCF was comparable to the GT (p = 0.129, 0.502, and 0.130 for surgical, biopsies, and cell block, respectively) and demonstrated good reliability if elaborated by different pathologists (Wk = 0.9). Overall cTCF was lower as compared to pTCF (30 ± 10 vs 52 ± 19, p < 0.001), with more cases < 20% (17, 14%, p = 0.690), but none containing < 100 cells for the algorithm. Similarities were noted between tumor area estimation and pTCF (36 ± 29, p < 0.001), partly explaining variability in the human assessment of tumor cellularity. Finally, the cTCF allowed a reduction of the copy number variations (CNVs) called (27 vs 29, - 6.9%) with an increase of effective CNVs detection (13 vs 7, + 85.7%), some with potential clinical impact previously undetected with pTCF. An automated computational pipeline (Qupath Analysis of Nuclei from Tumor to Uniform Molecular tests, QuANTUM) has been created and is freely available as a QuPath extension. The computational method used in this study has the potential to improve efficacy and reliability of TCF estimation in NSCLC, with demonstrated impact on the final molecular results.

Innate Immunity Activation in Newly Diagnosed Ileocolonic Crohn's Disease: A Cohort Study.

BACKGROUND: Recent studies showed that early surgery for Crohn's disease leads to a lower recurrence rate. However, the underlying mechanism is unknown. OBJECTIVE: The study aims to analyze the innate immunity microenvironment in ileal mucosa according to the duration of Crohn's disease. DESIGN: A prospective cohort study. SETTINGS: Tertiary referral center for IBD surgery. PATIENTS: A total of 88 consecutive patients with Crohn's disease undergoing ileocolonic resection were prospectively enrolled. Mucosal samples were obtained from both healthy and inflamed ileum. Data from a public data set were analyzed as an external validation cohort. MAIN OUTCOME MEASURES: Neutrophil infiltration was evaluated by histological asessment and macrophage subpopulation was assessed by immunohistochemistry. Expressions of TLR2 , TLR4 , TLR5 , DEFB1 , DEFB4A , DEFB103 , DEFA5 , and DEFA6 were quantified by real-time quantitative polymerase chain reaction. Concentrations of BDNF, CCL-11, ICAM-1, IL-1A, IL-1ß, IL-1RN, IL-12p40, IL-12p70, IL-15, IL-17A, IL-23A, MMP-3, CCL-3, KITLG, and VEGFA were determined with an immunometric assay. RESULTS: Neutrophil infiltration is inversely correlated with disease duration. DEFB4A mRNA expression tended to be higher in late-stage Crohn's disease ( p = 0.07). A higher number of macrophages expressed CD163 at low intensity in late-stage Crohn's disease ( p = 0.04). The concentration of IL-15 ( p = 0.02) and IL-23A ( p = 0.05) was higher in healthy ileal mucosa of early-stage patients. In the external cohort, expressions of DEFB1 ( p = 0.03), DEFB4A ( p = 0.01), IL-2 ( p = 0.04), and IL-3 ( p = 0.03) increased in patients with late-stage Crohn's disease. LIMITATIONS: A relatively small number of patients, especially in the newly diagnosed group. CONCLUSIONS: In newly diagnosed Crohn's disease, high levels of IL-15 and IL-23 in healthy mucosa suggest that innate immunity is the starter of acute inflammation. Moreover, M2 macrophages increase in the healthy mucosa of patients with late-stage Crohn's disease, suggesting that reparative and profibrotic processes are predominant in the long term, and in this phase, anti-inflammatory therapy may be less efficient. See Video Abstract . ACTIVACIN DE LA INMUNIDAD INNATA EN LA RECIENTEMENTE DIAGNOSTICADA ENFERMEDAD DE CROHN ILEOCLICA UN ESTUDIO DE COHORTE: ANTECEDENTES:Estudios recientes demostraron que la cirugía temprana para la enfermedad de Crohn (EC) conduce a una menor tasa de recurrencia. Sin embargo, se desconoce el mecanismo subyacente.OBJETIVO:El estudio tiene como objetivo analizar el microambiente de la inmunidad innata en la mucosa ileal según la duración de la EC.DISEÑO:Un estudio de cohorte prospectivo.AJUSTES:Centro terciario de referencia para cirugía de EII.PACIENTES:Fueron registrados de manera prospectiva y consecutiva 88 pacientes con EC sometidos a resección ileocolónica. Se obtuvieron muestras de mucosa ileal, tanto del íleon sano como del íleon inflamado. Los datos se analizaron como una cohorte de validación externa.PRINCIPALES MEDIDAS DE RESULTADO:Fueron evaluados la infiltración de neutrófilos por histología y la subpoblación de macrófagos por inmunohistoquímica. La expresión de TLR2, TLR4, TLR5, DEFB1, DEFB4A, DEFB103, DEFA5 y DEFA6 fueron cuantificados mediante qPCR en tiempo real. Las concentraciones de BDNF, CCL-11, ICAM-1, IL-1A, IL-1B, IL-1RN, IL-12 p40, IL-12 p70, IL-15, IL-17A, IL-23A, MMP-3, CCL-3, KITLG, VEGFA se determinaron con ensayo inmunométrico.RESULTADOS:La infiltración de neutrófilos se correlaciona inversamente con la duración de la enfermedad. La expresión del ARNm de DEFB4A mostro una tendencia a ser mayor en la EC en etapa tardía ( p = 0,07). Un mayor número de macrófagos expresaron CD163 a baja intensidad en la etapa tardía ( p = 0,04). La concentración de IL15 ( p = 0,02) e IL23A ( p = 0,05) fue mayor en la mucosa ileal sana de pacientes en estadio temprano. En la cohorte externa, la expresión de DEFB1 ( p = 0,03) y DEFB4A ( p = 0,01), IL2 ( p = 0,04) e IL3 ( p = 0,03) aumentó en pacientes en etapa tardía.LIMITACIONES:Un número relativamente pequeño de pacientes, especialmente en el grupo recién diagnosticado.CONCLUSIONES:En la EC recién diagnosticada, los altos niveles de IL-15 e IL-23 en la mucosa sana sugieren que la inmunidad innata es el promotor de la inflamación aguda. Además, los macrófagos M2 aumentan en la mucosa sana de pacientes con EC en etapa tardía, lo que sugiere que los procesos reparadores y profibróticos son predominantes a largo plazo y en esta fase, la terapia antiinflamatoria puede ser menos eficiente. (Traducción-Dr. Osvaldo Gauto ).

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.

Circulating microRNA analysis in a prospective co-clinical trial identifies MIR652-3p as a response biomarker and driver of regorafenib resistance mechanisms in colorectal cancer.

BACKGROUND: The multi-kinase inhibitor regorafenib has demonstrated efficacy in chemo-refractory metastatic colorectal cancer (mCRC) patients. However, lack of predictive biomarkers and concerns over significant toxicities hamper the use of regorafenib in clinical practice. METHODS: Serial liquid biopsies were obtained at baseline and monthly until disease progression in chemo-refractory mCRC patients treated with regorafenib in a phase II clinical trial (PROSPECT-R n=40; NCT03010722) and in a multicentric validation cohort (n=241). Tissue biopsies collected at baseline, after 2 months and at progression in the PROSPECT-R trial were used to establish Patient-Derived Organoids (PDOs) and for molecular analyses. MicroRNA profiling was performed on baseline bloods using the NanoString nCounter platform and results were validated by digital droplet PCR and/or In Situ Hybridization in paired liquid and tissue biopsies. PDOs co-cultures and PDO-xenotransplants were generated for functional analyses. RESULTS: Large-scale microRNA expression analysis in longitudinal matched liquid and tissue biopsies from the PROSPECT-R trial identified MIR652-3p as a biomarker of clinical benefit to regorafenib. These findings were confirmed in an independent validation cohort and in a "control" group of 100 patients treated with lonsurf. Using ex vivo co-culture assays paired with single-cell RNA-sequencing of PDO established pre- and post-treatment, we modelled regorafenib response observed in vivo and in patients, and showed that MIR652-3p controls resistance to regorafenib by impairing regorafenib-induced lethal autophagy and by orchestrating the switch from neo-angiogenesis to vessel co-option. CONCLUSIONS: Our results identify MIR652-3p as potential biomarker and as a driver of cell and non-cell autonomous mechanisms of resistance to regorafenib.

Crosstalk between MicroRNAs and Oxidative Stress in Coeliac Disease.

MicroRNAs (miRNAs) are small, non-coding RNA molecules involved in regulating gene expression. Many studies, mostly conducted on pediatric patients, suggested that oxidative stress and several miRNAs may play an important role in coeliac disease (CeD) pathogenesis. However, the interplay between oxidative stress and miRNA regulatory functions in CeD remains to be clarified. In this review, we aimed to perform a literature review on the role of miRNAs and oxidative stress in adult CeD patients and to analyze their potential interactions. In this direction, we also reported the preliminary results of a pilot study we recently performed.

Claudin-18.2 testing and its impact in the therapeutic management of patients with gastric and gastroesophageal adenocarcinomas: A literature review with expert opinion.

Claudin-18.2 (CLDN18.2) is a member of the tight junction protein family and is a highly selective biomarker with frequent abnormal expression during the occurrence and development of various primary malignant tumors, including gastric cancer (GC) and esophago-gastric junction adenocarcinomas (EGJA). For these reasons, CLDN18.2 has been investigated as a therapeutic target for GC/EGJA malignancies. Recently, zolbetuximab has been proposed as a new standard of care for patients with CLDN18.2-positive, HER2-negative, locally advanced and metastatic GC/EGJA. The use of CLDN18 IHC assays to select patients who might benefit from anti-CLDN18.2 therapy is currently entering clinical practice. In this setting, pathologists play a central role in therapeutic decision-making. Accurate biomarker assessment is essential to ensure the best therapeutic option for patients. In the present review, we provide a comprehensive overview of available evidence on CLDN18.2 testing and its impact on the therapeutic management of patients with GC/EGJA, as well as some practical suggestions for CLDN18.2 staining interpretation and potential pitfalls in the real-world setting.

Practical guidelines for molecular testing of cholangiocarcinoma in clinical practice: Italian experts' position paper.

Biliary tract cancers (BTCs) represent a spectrum of malignancies associated with a dismal prognosis. Recent genomic profiling studies have provided a deeper understanding of the complex and heterogenous molecular landscape of BTCs, identifying several actionable genetic alterations, and expanding treatment options. Due to the high number and complexity of genetic alterations which require testing, next-generation sequencing (NGS) is currently the preferred approach over conventional methods (i.e., immunohistochemistry, fluorescence in-situ hybridization and PCR) for molecular profiling of BTCs and should be performed upfront in all BTC patients. However, BTC sampling often yields low tumor cellularity tissue, hampering NGS analysis. Future perspectives to overcome this obstacle include liquid biopsy and optimization of biopsy protocols. In this position paper, the authors discuss the current histopathologic, molecular, and therapeutic landscape of BTCs, provide a critical overview of the available testing methods for molecular diagnostics, and propose a practical diagnostic algorithm for molecular testing of BTC samples.

SerpinB3/4 Expression Is Associated with Poor Prognosis in Patients with Cholangiocarcinoma.

Cholangiocarcinoma (CCA), the second most common primary liver tumor, is associated with a dismal outcome, and useful prognostic markers are not currently available in clinical practice. SerpinB3, a serine protease inhibitor, was recently found to play a relevant role in malignant transformation in different cancers. The aim of the present study was to determine the expression of SerpinB3/4 in tissue and serum samples of patients with CCA in relation to clinical outcomes. SerpinB3/4 was assessed in the tissue microarrays (TMAs) of 123 surgically resected CCAs. ELISA assays were carried out in 188 patients with CCA to detect the free and IgM-linked forms of SerpinB3/4. Overall survival was analyzed in relation to SerpinB3/4 expression, and Cox models were used to identify the variables associated with survival. High levels of SerpinB3/4 (TMA score 2+/3+) were detected in 15 tumors (12.2%), characterized by a more advanced TNM stage (III/IV: 64.3% vs. 31.3%; p = 0.031) and lower overall patient survival, independently of CCA subclass (intrahepatic CCA: median 1.1 (0.8-Not Estimable, NE) vs. 2.4 (1.8-3.4) years; p = 0.0007; extrahepatic CCA: median 0.8 (0.2-NE) vs. 2.2 (1.5-5.4) years; p = 0.011). Vascular invasion (p = 0.027) and SerpinB3/4 scores (p = 0.0016) were independently associated with mortality in multivariate analysis. Patients who had detectable free or IgM-linked SerpinB3/4 in their serum showed poorer survival (1 vs. 2.4 years, p = 0.015, for free SerpinB3/4, and 1 vs. 2.6 years, p = 0.0026, for SerpinB3/4-IgM). In conclusion, high levels of SerpinB3/4 in tissue and serum in CCA are associated with poor outcomes after surgery, regardless of tumor subclass.

BRAFV600E immunohistochemistry can reliably substitute BRAF molecular testing in the Lynch syndrome screening algorithm in colorectal cancer.

AIMS: The Lynch syndrome (LS) screening algorithm requires BRAF testing as a fundamental step to distinguish sporadic from LS-associated colorectal carcinomas (CRC). BRAF testing by immunohistochemistry (IHC) has shown variable results in the literature. Our aim was to analyse concordance between BRAFV600E IHC and BRAF molecular analysis in a large, mono-institutional CRC whole-slide, case series with laboratory validation. METHODS AND RESULTS: MisMatch repair (MMR) protein (hMLH1, hPMS2, hMSH2, and hMSH6) and BRAFV600E IHC were performed on all unselected cases of surgically resected CRCs (2018-2023). An in-house validation study for BRAFV600E IHC was performed in order to obtain optimal IHC stains. BRAFVV600E IHC was considered negative (score 0), positive (scores 2-3), and equivocal (score 1). Interobserver differences in BRAFV600E IHC scoring were noted in the first 150 cases prospectively collected. Nine-hundred and ninety CRCs cases (830 proficient (p)MMR/160 deficient (d)MMR) were included and all cases performed BRAFV600E IHC (BRAFV600E IHC-positive 13.5% of all series; 66.3% dMMR cases; 3.4% pMMR cases), while 333 also went to BRAF mutation analysis. Optimal agreement in IHC scoring between pathologists (P < 0.0001) was seen; concordance between BRAFV600E IHC and BRAF molecular analysis was extremely high (sensitivity 99.1%, specificity 99.5%; PPV 99.1%, and NPV 99.5%). Discordant cases were reevaluated; 1 score 3 + IHC/wildtype case was an interpretation error and one score 0 IHC/mutated case was related to heterogenous BRAFV600E IHC expression. Among the 12 IHC-equivocal score 1+ cases (which require BRAF molecular analysis), three were BRAF-mutated and nine BRAF-wildtype. CONCLUSION: BRAFV600E IHC can be used as a reliable surrogate of molecular testing after stringent in-house validation.

Non-Small Cell Lung Cancer Testing on Reference Specimens: An Italian Multicenter Experience.

INTRODUCTION: Biomarker testing is mandatory for the clinical management of patients with advanced non-small cell lung cancer (NSCLC). Myriads of technical platforms are now available for biomarker analysis with differences in terms of multiplexing capability, analytical sensitivity, and turnaround time (TAT). We evaluated the technical performance of the diagnostic workflows of 24 representative Italian institutions performing molecular tests on a series of artificial reference specimens built to mimic routine diagnostic samples. METHODS: Sample sets of eight slides from cell blocks of artificial reference specimens harboring exon 19 EGFR (epidermal growth factor receptor) p.E746_AT50del, exon 2 KRAS (Kirsten rat sarcoma viral oncogene homologue) p.G12C, ROS1 (c-ros oncogene 1)-unknown gene fusion, and MET (MET proto-oncogene, receptor tyrosine kinase) Δ exon 14 skipping were distributed to each participating institution. Two independent cell block specimens were validated by the University of Naples Federico II before shipment. Methodological and molecular data from reference specimens were annotated. RESULTS: Overall, a median DNA concentration of 3.3 ng/µL (range 0.1-10.0 ng/µL) and 13.4 ng/µL (range 2.0-45.8 ng/µL) were obtained with automated and manual technical procedures, respectively. RNA concentrations of 5.7 ng/µL (range 0.2-11.9 ng/µL) and 9.3 ng/µL (range 0.5-18.0 ng/µL) were also detected. KRAS exon 2 p.G12C, EGFR exon 19 p.E736_A750del hotspot mutations, and ROS1 aberrant transcripts were identified in all tested cases, whereas 15 out of 16 (93.7%) centers detected MET exon 14 skipping mutation. CONCLUSIONS: Optimized technical workflows are crucial in the decision-making strategy of patients with NSCLC. Artificial reference specimens enable optimization of diagnostic workflows for predictive molecular analysis in routine clinical practice.

Application of a pattern-based approach to histological diagnosis in very early onset IBD (VEO-IBD) in a multicentric cohort of children with emphasis on monogenic disease with IBD-like morphology.

AIMS: Very early-onset inflammatory bowel disease (VEO-IBD) is a clinical umbrella term referring to IBD-like symptoms arising in children before the age of 6 years, encompassing both 'pure' IBD, such as ulcerative colitis (UC) and Crohn's disease (CD) and monogenic diseases (MDs), the latter often involving genes associated with primary immunodeficiencies. Moreover, histological features in gastrointestinal (GI) biopsies in MD can also have IBD-like morphology, making differential diagnosis difficult. Correct diagnosis is fundamental, as MDs show a more severe clinical course and their inadequate/untimely recognition leads to inappropriate therapy. METHODS AND RESULTS: Biopsy samples from the lower and upper GI tract of 93 clinically diagnosed VEO-IBD children were retrospectively selected in a multicentre cohort and histologically re-evaluated by 10 pathologists blinded to clinical information. Each case was classified according to morphological patterns, including UC-like; CD-like; enterocolitis-like; apoptotic; eosinophil-rich; and IBD-unclassified (IBD-U). Nine (69%) MD children showed IBD-like morphology; only the IBD-U pattern correlated with MD diagnosis (P = 0.02) (available in 64 cases: 51 non-MD, true early-onset IBD/other; 13 MD cases). MD patients showed earlier GI symptom onset (18.7 versus 26.9 months) and were sent to endoscopy earlier (22 versus 37 months), these differences were statistically significant (P < 0.05). Upper GI histology was informative in 37 biopsies. CONCLUSIONS: The diagnosis of the underlying cause of VEO-IBD requires a multidisciplinary setting, and pathology, while being one of the fundamental puzzle pieces, is often difficult to interpret. A pattern-based histological approach is therefore suggested, thus aiding the pathologist in VEO-IBD reporting and multidisciplinary discussion.

Immune-Related Diarrhea and Colitis in Non-small Cell Lung Cancers: Impact of Multidisciplinary Management in a Real-World Setting.

INTRODUCTION: Immune-related adverse events (irAEs) constitute a challenge in the clinical management of solid tumors. This study aims to collect real-world data on the occurrence of immune-mediated diarrhea and colitis (IMDC) in advanced non-small cell lung cancer (aNSCLC) treated with immune checkpoint inhibitors (ICIs) and to assess the clinical impact of a multidisciplinary approach (MDA) on IMDC management. METHODS: We retrospectively collected data on patients with aNSCLC consecutively treated with ICIs, either as single agent or in combination with chemotherapy, between September 2013 and July 2022. Among patients developing IMDC, we conducted blinded revision of colonic biopsies and evaluated the clinical impact of the introduction of MDA through predefined indicators. RESULTS: Among the 607 patients included, 84 (13.8%) experienced IMDC. Pathological review highlighted a high prevalence of microscopic colitis (28%), with a collagenous pattern linked to longer symptoms duration (P = .01). IMDC occurred more frequently in females (P = .05) and PD-L1 expressors (P = .014) and was correlated with longer progression-free survival (17.0 vs 5.8, P < .001) and overall survival (28.3 vs 9.5, P < .001). The introduction of MDA was associated with increased employment of diagnostical tools such as fecal calprotectin test (P < .001), colonoscopy (P < .001), and gastroenterological evaluation (P = .017) and a significant decrease in both grade 3 conversion rate (P = .046) and recurrence after rechallenge (P = .016). Hospitalization rate dropped from 17.2% to 3.8% (P: ns). CONCLUSION: These findings highlight the clinical relevance of IMDC and support the incorporation of a MDA to optimize the clinical management of this irAE to improve patient care. Prospective validation has been planned.

IDH1-mutated Crohn's disease-associated small bowel adenocarcinomas: Distinctive pathological features and association with MGMT methylation and serrated-type dysplasia.

AIMS: Patients with Crohn's disease (CrD) have an elevated risk for the development of small bowel adenocarcinomas (SBAs). Actionable isocitrate dehydrogenase 1 (IDH1) mutations have been reported to be more frequent in CrD-SBAs than in sporadic SBAs. The present study aimed to investigate the clinicopathological and immunophenotypical features, as well as methylation profiles, of IDH1-mutated CrD-SBAs. METHODS AND RESULTS: An international multicentre series of surgically resected CrD-SBAs was tested for IDH1 mutation. Clinicopathological features, immunophenotypical marker expression and O6-methylguanine-DNA methyltransferase (MGMT) and long interspersed nuclear element-1 (LINE-1) methylation were compared between IDH1-mutated and IDH1 wild-type CrD-SBAs. Ten (20%) of the 49 CrD-SBAs examined harboured an IDH1 mutation and all the mutated cancers harboured the R132C variant. Compared to IDH1 wild-type cases, IDH1-mutated CrD-SBAs showed significantly lower rates of cytokeratin 7 expression (P = 0.005) and higher rates of p53 overexpression (P = 0.012) and MGMT methylation (P = 0.012). All three dysplastic growths associated with IDH1-mutated SBAs harboured the same IDH1 variant (R132C) of the corresponding invasive cancer, and all were of non-conventional subtype (two serrated dysplastic lesions and one goblet cell-deficient dysplasia). In particular, non-conventional serrated dysplasia was significantly associated with IDH1-mutated CrD-SBAs (P = 0.029). No significant cancer-specific survival difference between IDH1-mutated CrD-SBA patients and IDH1 wild-type CrD-SBA patients was found (hazard ratio = 0.55, 95% confidence interval = 0.16-1.89; P = 0.313). CONCLUSIONS: IDH1-mutated CrD-SBAs, which represent approximately one-fifth of total cases, are characterised by distinctive immunophenotypical features and methylation profiles, with potential therapeutic implications. Moreover, IDH1-mutated non-conventional, serrated dysplasia is likely to represent a precursor lesion to such CrD-SBAs.

Multiple colorectal adenomas syndrome: The role of MUTYH mutation and the polyps' number in clinical management and colorectal cancer risk.

BACKGROUND & AIMS: Multiple colorectal adenomas (MCRAs) can result from APC (AFAP) or biallelic MUTYH (MAP) mutations, but most patients are wild type and referred to as non-APC/MUTYH polyposis (NAMP). We aim to examine the risk of colorectal cancer (CRC) and the role of endoscopy in managing patients with MCRAs, with a specific focus on clinical features and genotype. METHODS: Records of MRCAs between 2000 and 2022 were retrospectively analysed. Patients were divided according to the genotype (MAP vs. NAMP) and the number of categorised polyps' burden (group 1: 10-24, group 2: 25-49, and group 3: 50-99 adenomas). Predictors of outcome were CRC-free survival (CRC-FS) and Surgery free-survival (S-FS). RESULTS: 220 patients were enrolled (NAMP n = 178(80.0%)). CRC at diagnosis was more frequent in group 3 (p = 0.01), without significant differences between the genotypes (p = 0.20). At a follow-up of 83(41-164) months, 15(7%) patients developed CRC during surveillance. CRC-FS was not correlated to genotype (p = 0.07) or polyps' number (p = 0.33), while S-FS was similar in MAP and NAMP (p = 0.22) and lower in groups 2 and 3 (p = 0.0001). CONCLUSIONS: MAP and NAMP have the same CRC risk and no difference in treatment. Endoscopic surveillance compared favorably with surgery in avoiding CRC risk, even in patients with more severe colorectal polyposis.

Prevalence and type of MMR expression heterogeneity in colorectal adenocarcinoma: therapeutic implications and reporting.

Mismatch repair (MMR) immunohistochemical (IHC) evaluation has entered pathology routine practice as the first-line screening method to identify patients with MMR deficient (MMRd)/microsatellite instability (MSI) colorectal cancer (CRC), and its misdiagnosis may significantly impact the personalization of CRC patient care. To determine the prevalence of MMR protein intratumor heterogeneity in real-world practice, we collected a series of 8282 CRCs tested for MMR proteins in the setting of Lynch syndrome universal screening. Four heterogenous cases were also investigated for tumor infiltrating lymphocytes count, MSI status, and consensus molecular subtypes by Nanostring nCounter® Platform. Overall, 1056 (12.8%) CRCs showed a MMR altered status, with 46 cases showing a heterogeneous MMR profile (0.56% of the total, and 4.36% of all MMRd cases). To conclude, the authors make some critical remarks regarding the approach to MMR heterogeneity in clinical practice and routine diagnostics.

Synchronous Endometrial and Ovarian Carcinomas: Pathologic and Molecular Analysis Highlights the Monoclonal Origin of the Lesions.

The diagnosis of synchronous carcinomas, involving both the endometrium and ovaries, is not a rare finding in gynecologic pathology and represents a challenge with implications on tumor staging and therapeutic decision-making. A mono-institutional series of 11 metastatic and 6 paired synchronous endometrial and ovarian carcinomas were reviewed by 2 expert pathologists based on previously published histopathologic criteria. The series was investigated for DNA mismatch repair proteins, p53, and POLE status and was subject to DNA-based next-generation sequencing targeting 67 cancer-related genes. Out of 17 pairs, 16 featured the same histotype (10 endometrioid, 4 serous high-grade, and 2 clear cells). By using WHO 2020 criteria, 11 couples of tumors were confirmed as metastatic and 6 couples were confirmed as independent. Based on next-generation sequencing analysis, 16 of 17 cases (11 metastatic and 5 independent) of our series showed evidence of a clonal relationship between endometrial and ovarian carcinomas. In metastatic cases, the adverse outcome was associated with nonendometrioid/high-grade endometrioid histotype and with the p53-abnormal molecular subtype. Four cases originally fulfilling clinicopathological criteria of independent endometrial and ovarian carcinomas were clonally related, low-grade endometrioid histotype and POLE-mut, mismatch repair deficient, and no specific molecular profile molecular subtypes; no adverse event was recorded in this group. In summary, the molecular characterization of synchronous gynecologic carcinomas confirms their clonal origin in most cases. However, the results of our study point out that the clinical behavior of these tumors seems to be determined by the presence of high-risk WHO 2020 histologic criteria and molecular features (i.e. p53-abnormal), rather than the monoclonal origin.