Brentuximab vedotin for skin involvement in refractory diffuse cutaneous systemic sclerosis, an open-label trial.

OBJECTIVE: We explored the efficacy and safety of brentuximab vedotin, a chimeric anti-CD30 antibody drug conjugate, in patients with severe active diffuse cutaneous systemic sclerosis (dcSSc). METHODS: This phase II proof-of-concept, single center, open-label, single arm, investigator-initiated trial included patients ≥18 years, with dcSSc, modified Rodnan skin score (mRSS) ≥15 with <5 years since the first non-Raynaud's symptom and/or skin worsening despite immunosuppression who were treated with intravenous brentuximab vedotin 0.6 mg/Kg q3 weeks for 45 weeks. The primary end point was a decrease in mRSS of ≥ 8 points at 48 weeks. RESULTS: Eleven patients were treated with brentuximab vedotin, with 9 completing the study. The mean mRSS reduction at week 48 was 11.3 (95% CI 6.9, 15.8; p= 0.001), meeting the primary end point in the intention to treat analysis (7/11 had a decrease in mRSS ≥8). The % forced vital capacity increased by 7.8% (12.5). The Composite Response Index in dcSSc (CRISS) suggested a beneficial treatment effect (86% ≥0.6). Most adverse events were mild. No SAEs were attributed to brentuximab vedotin. CONCLUSION: In dcSSc, brentuximab vedotin improved skin and FVC; without safety concerns. A placebo-controlled trial is warranted to corroborate these initial findings.

Ten Years of Pathology on Twitter (X): Landscape and Evolution of Pathology on Twitter From 2012 to 2023.

CONTEXT.­: Social media is a powerful tool in pathology education and professional networking that connects pathologists and pathology trainees from around the world. Twitter (X) appears to be the most popular social media platform pathologists use to share pathology-related content and connect with other pathologists. Although there has been some published research on pathology-related activity on Twitter during short time frames, to date there has not been published research examining pathology-related Twitter activity in totality from its earliest days of activity to recently. OBJECTIVE.­: To comprehensively evaluate the use of pathology on Twitter (X) during the last 10 years. DESIGN.­: Pathology-related tweets were systematically scraped from Twitter from January 2012 to January 2023 using pathology hashtags as a surrogate measure for all pathology content on Twitter. COVID-related tweets were approximated by tweets containing the term "COVID." RESULTS.­: There were 591 812 unique pathology-related tweets identified during the time period, with #pathology being the most common hashtag used and #PathTwitter becoming more popular since 2020. There has been positive annual growth of pathology Twitter, with peaks in use during major pathology conferences. During the initial phases of the COVID-19 pandemic a sustained increase in pathology tweets was observed. CONCLUSIONS.­: Pathology Twitter has grown during the last 10 years and has become increasingly popular for pathology education and networking. With the changing landscape of social media platforms this study provides an understanding of how pathology medical education and professional networking uses of social media are used and evolve over time.

The genomic and evolutionary landscapes of anaplastic thyroid carcinoma.

Anaplastic thyroid carcinoma is arguably the most lethal human malignancy. It often co-occurs with differentiated thyroid cancers, yet the molecular origins of its aggressivity are unknown. We sequenced tumor DNA from 329 regions of thyroid cancer, including 213 from patients with primary anaplastic thyroid carcinomas. We also whole genome sequenced 9 patients using multi-region sequencing of both differentiated and anaplastic thyroid cancer components. Using these data, we demonstrate thatanaplastic thyroid carcinomas have a higher burden of mutations than other thyroid cancers, with distinct mutational signatures and molecular subtypes. Further, different cancer driver genes are mutated in anaplastic and differentiated thyroid carcinomas, even those arising in a single patient. Finally, we unambiguously demonstrate that anaplastic thyroid carcinomas share a genomic origin with co-occurring differentiated carcinomas and emerge from a common malignant field through acquisition of characteristic clonal driver mutations.

Assessment of Pathology Domain-Specific Knowledge of ChatGPT and Comparison to Human Performance.

CONTEXT.­: Artificial intelligence algorithms hold the potential to fundamentally change many aspects of society. Application of these tools, including the publicly available ChatGPT, has demonstrated impressive domain-specific knowledge in many areas, including medicine. OBJECTIVES.­: To understand the level of pathology domain-specific knowledge for ChatGPT using different underlying large language models, GPT-3.5 and the updated GPT-4. DESIGN.­: An international group of pathologists (n = 15) was recruited to generate pathology-specific questions at a similar level to those that could be seen on licensing (board) examinations. The questions (n = 15) were answered by GPT-3.5, GPT-4, and a staff pathologist that recently passed their Canadian pathology licensing exams. Participants were instructed to score answers on a 5-point scale and to predict which answer was written by ChatGPT. RESULTS.­: GPT-3.5 performed at a similar level to the staff pathologist, while GPT-4 outperformed both. The overall score for both GPT-3.5 and GPT-4 was within the range of meeting expectations for a trainee writing licensing examinations. In all but one question, the reviewers were able to correctly identify the answers generated by GPT-3.5. CONCLUSIONS.­: By demonstrating the ability of ChatGPT to answer pathology-specific questions at a level similar to (GPT-3.5) or exceeding (GPT-4) a trained pathologist, this study highlights the potential of large language models to be transformative in this space. In the future, more advanced iterations of these algorithms with increased domain-specific knowledge may have the potential to assist pathologists and enhance pathology resident training.

Evolving educational landscape in pathology: a comprehensive bibliometric and visual analysis including digital teaching and learning resources.

AIMS: Pathology education is a core component of medical training, and its literature is critical for refining educational modalities. We performed a cross-sectional bibliometric analysis to explore publications on pathology education, focusing on new medical education technologies. METHODS: The analysis identified 64 pathology journals and 53 keywords. Relevant articles were collected using a web application, PaperScraper, developed to accelerate literature search. Citation data were collected from multiple sources. Descriptive statistics, with time period analysis, were performed using Microsoft Excel and visualised with Flourish Studio. Two article groups were further investigated with a bibliometric software, VOSViewer, to establish co-authorship and keyword relationships. RESULTS: 8946 citations were retrieved from 905 selected articles. Most articles were published in the last decade (447, 49.4%). The top journals were Archives of Pathology & Laboratory Medicine (184), Human Pathology (122) and the American Journal of Clinical Pathology (117). The highest number of citations was found for Human Pathology (2120), followed by Archives of Pathology & Laboratory Medicine (2098) and American Journal of Clinical Pathology (1142). Authors with different backgrounds had the greatest number of articles and citations. 12 co-authorship, 3 keyword and 8 co-citation clusters were found for the social media/online resources group, 8 co-authorship, 4 keyword and 7 co-citation clusters for the digital pathology/virtual microscopy/mobile technologies group. CONCLUSIONS: The analysis revealed a significant increase in publications over time. The emergence of digital teaching and learning resources played a major role in this growth. Overall, these findings underscore the transformative potential of technology in pathology education.

Clinical Presentation and Genomic Analysis of HPV-Related Squamous Cell Carcinoma of the Larynx in Two Young Female Patients.

Laryngeal cancer most frequently develops in males aged 60-70 years with a history of tobacco and/or alcohol use, while fewer cases occur in young patients in which tobacco and alcohol are often absent or less significant, highlighting the importance of other etiologies. We present cases of human papillomavirus (HPV)-associated laryngeal cancer in two previously healthy young women. A retrospective case review was carried out for both patients. DNA was extracted from the primary tumors and matched to normal tissue or blood, HPV genotype was determined by PCR and whole exome sequencing was carried out. Genomic results were pooled with laryngeal cancer patients from the cancer genome atlas (TCGA) dataset. The first patient was an 18-year-old female who underwent laryngectomy followed by adjuvant radiation. The second was a 24-year-old female who received chemoradiation. The first patient has remained disease-free for 16 years and the second for two years; both continue to be monitored. One tumor was positive for HPV45 and had mutations in FAT1 and FAT2; the other was positive for HPV31 and had mutations at NOTCH1, MAPK1, and HIST1H2AK. Both tumors had wild-type TP53 alleles. We bring attention to HPV as an etiology of laryngeal carcinoma in young patients, which may have implications for the treatment and prognosis of similar patients.

Stereotactic ablative radiotherapy before resection to avoid delay for early-stage lung cancer or oligometastases during the COVID-19 pandemic: Pathologic outcomes from the SABR-BRIDGE protocol.

BACKGROUND: During coronavirus disease 2019 (COVID-19)-related operating room closures, some multidisciplinary thoracic oncology teams adopted a paradigm of stereotactic ablative radiotherapy (SABR) as a bridge to surgery, an approach called SABR-BRIDGE. This study presents the preliminary surgical and pathological results. METHODS: Eligible participants from four institutions (three in Canada and one in the United States) had early-stage presumed or biopsy-proven lung malignancy that would normally be surgically resected. SABR was delivered using standard institutional guidelines, with surgery >3 months following SABR with standardized pathologic assessment. Pathological complete response (pCR) was defined as absence of viable cancer. Major pathologic response (MPR) was defined as ≤10% viable tissue. RESULTS: Seventy-two patients underwent SABR. Most common SABR regimens were 34 Gy/1 (29%, n = 21), 48 Gy/3-4 (26%, n = 19), and 50/55 Gy/5 (22%, n = 16). SABR was well-tolerated, with one grade 5 toxicity (death 10 days after SABR with COVID-19) and five grade 2-3 toxicities. Following SABR, 26 patients underwent resection thus far (13 pending surgery). Median time-to-surgery was 4.5 months post-SABR (range, 2-17.5 months). Surgery was reported as being more difficult because of SABR in 38% (n = 10) of cases. Thirteen patients (50%) had pCR and 19 (73%) had MPR. Rates of pCR trended higher in patients operated on at earlier time points (75% if within 3 months, 50% if 3-6 months, and 33% if ≥6 months; p = .069). In the exploratory best-case scenario analysis, pCR rate does not exceed 82%. CONCLUSIONS: The SABR-BRIDGE approach allowed for delivery of treatment during a period of operating room closure and was well-tolerated. Even in the best-case scenario, pCR rate does not exceed 82%.

Using deep learning to predict tumor mutational burden from scans of H&E-stained multicenter slides of lung squamous cell carcinoma.

Purpose: A high tumor mutational burden (TMB) is a promising biomarker for identifying lung squamous cell carcinoma (SqCC) patients who are more likely to benefit from risky but potentially highly beneficial immunotherapy, but it is not available in most clinics. It has been shown that it is possible to predict TMB from standard-of-care cancer histology slides using deep learning for various cancer sites. Our goal is to build a model that can do this specifically for lung SqCC and to validate it on a held-out test set from centers on which the model was not trained. Approach: We obtained scans of diagnostic slides from 50 lung SqCC patients, with one slide per-patient, from 35 different centers. We held out 20 slides from 15 centers for testing and used the rest for training and validation, ensuring that no center was represented in more than one set. Using transfer learning, we explored several neural network architectures and training parameters to choose an optimal model. Results: Using the training and validation sets, we found the optimal model to be VGG16. The per-patient AUC for this model on the held-out test set was 0.65, with an accuracy of 65%, true positive rate of 77%, and true negative rate of 43%. Conclusions: A deep learning model can predict TMB from scans of H&E-stained slides of lung SqCC resections on an independent test set containing images only from centers on which the model was not trained. With further development and external validation, such a system can act as an alternative to traditional genetic sequencing for patients with SqCC; this will help physicians determine, with more accuracy, whether patients should be given immunotherapy. This will more effectively give access to immunotherapy drugs to those who need them and help spare others the toxicities associated with them.

Digital Quantification of Tumor Cellularity as a Novel Prognostic Feature of Non-Small Cell Lung Carcinoma.

Non-small cell lung carcinoma is currently staged based on the size and involvement of other structures. Tumor size may be a surrogate measure of the total number of tumor cells. A recently revised reporting system for adenocarcinoma incorporates high-risk histologic patterns, which may have increased cellular density. Modern digital image analysis tools can be utilized to automate the quantification of cells. In this study, we tested the hypothesis that tumor cellularity can be used as a novel prognostic tool for lung cancer. Digital slides from The Cancer Genome Atlas lung adenocarcinoma (ADC) data set (n = 213) and lung squamous cell carcinoma (SCC) data set (n = 90) were obtained and analyzed using QuPath. The number of tumor cells was normalized with the surface area of the tumor to provide a measure of tumor cell density. Tumor cellularity was calculated by multiplying the size of the tumor with the cell density. Major histologic patterns and grade were compared with the tumor density of the lung ADC and lung SCC cases. The overall and progression-free survival were compared between groups of high and low tumor cellularity. High-grade histologic patterns in the ADC and SCC cases were associated with greater tumor densities compared with low-grade patterns. Cases with lower tumor cellularity had improved overall and progression-free survival compared with cases with higher cellularity. These results support tumor cellularity as a novel prognostic tool for non-small cell lung carcinoma that considers tumor stage and grade elements.

Tumor-Infiltrating T Cells in EBV-Associated Gastric Carcinomas Exhibit High Levels of Multiple Markers of Activation, Effector Gene Expression, and Exhaustion.

Epstein-Barr virus (EBV) is a gamma-herpesvirus associated with 10% of all gastric cancers (GCs) and 1.5% of all human cancers. EBV-associated GCs (EBVaGCs) are pathologically and clinically distinct entities from EBV-negative GCs (EBVnGCs), with EBVaGCs exhibiting differential molecular pathology, treatment response, and patient prognosis. However, the tumor immune landscape of EBVaGC has not been well explored. In this study, a systemic and comprehensive analysis of gene expression and immune landscape features was performed for both EBVaGC and EBVnGC. EBVaGCs exhibited many aspects of a T cell-inflamed phenotype, with greater T and NK cell infiltration, increased expression of immune checkpoint markers (BTLA, CD96, CTLA4, LAG3, PD1, TIGIT, and TIM3), and multiple T cell effector molecules in comparison with EBVnGCs. EBVaGCs also displayed a higher expression of anti-tumor immunity factors (PDL1, CD155, CEACAM1, galectin-9, and IDO1). Six EBV-encoded miRNAs (miR-BARTs 8-3p, 9-5p, 10-3p, 22, 5-5p, and 14-3p) were strongly negatively correlated with the expression of immune checkpoint receptors and multiple markers of anti-tumor immunity. These profound differences in the tumor immune landscape between EBVaGCs and EBVnGCs may help explain some of the observed differences in pathological and clinical outcomes, with an EBV-positive status possibly being a potential biomarker for the application of immunotherapy in GC.

Immune-based classification of HPV-associated oropharyngeal cancer with implications for biomarker-driven treatment de-intensification.

BACKGROUND: There is significant interest in treatment de-escalation for human papillomavirus-associated (HPV+) oropharyngeal squamous cell carcinoma (OPSCC) patients given the generally favourable prognosis. However, 15-30% of patients recur after primary treatment, reflecting a need for improved risk-stratification tools. We sought to develop a molecular test to risk stratify HPV+ OPSCC patients. METHODS: We created an immune score (UWO3) associated with survival outcomes in six independent cohorts comprising 906 patients, including blinded retrospective and prospective external validations. Two aggressive radiation de-escalation cohorts were used to assess the ability of UWO3 to identify patients who recur. Multivariate Cox models were used to assess the associations between the UWO3 immune class and outcomes. FINDINGS: A three-gene immune score classified patients into three immune classes (immune rich, mixed, or immune desert) and was strongly associated with disease-free survival in six datasets, including large retrospective and prospective datasets. Pooled analysis demonstrated that the immune rich group had superior disease-free survival compared to the immune desert (HR = 9.0, 95% CI: 3.2-25.5, P = 3.6 × 10-5) and mixed (HR = 6.4, 95% CI: 2.2-18.7, P = 0.006) groups after adjusting for age, sex, smoking status, and AJCC8 clinical stage. Finally, UWO3 was able to identify patients from two small treatment de-escalation cohorts who remain disease-free after aggressive de-escalation to 30 Gy radiation. INTERPRETATION: With additional prospective validation, the UWO3 score could enable biomarker-driven clinical decision-making for patients with HPV+ OPSCC based on robust outcome prediction across six independent cohorts. Prospective de-escalation and intensification clinical trials are currently being planned. FUNDING: CIHR, European Union, and the NIH.

A Case of Li-Fraumeni Associated Thymoma.

Thymomas are among the most common cancers of the anterior mediastinum. They rarely occur in patients with Li-Fraumeni syndrome (LFS), a hereditary syndrome that predisposes individuals to cancer and is characterized by mutations in the tumor suppressor encoding gene TP53. Here we describe a case of primary thymoma in a woman diagnosed with LFS. We cover the initial presentation and diagnosis, radiological findings, histopathological examination, and management of thymoma. In addition, we review p53 physiology and LFS pathophysiology to explore how TP53 expression might differ between the majority of thymomas and in thymomas associated with LFS. This altered pathophysiology may affect management and prognosis due to emerging evidence of increased resistance to conventional treatment, which suggests a need for close monitoring and consideration of novel treatment strategies such as programmed death-ligand 1 (PD-L1) inhibitors.

Digital quantification of p16-positive foci in fibrotic interstitial lung disease is associated with a phenotype of idiopathic pulmonary fibrosis with reduced survival.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is associated with increased expression of cyclin-dependent kinase inhibitors such as p16 and p21, and subsequent induction of cell cycle arrest, cellular senescence, and pro-fibrotic gene expression. We sought to link p16-expression with a diagnosis of IPF or other fibrotic interstitial lung diseases (ILDs), radiographic pattern, senescent foci-specific gene expression, antifibrotic therapy response, and lung transplant (LTx)-free survival. METHODS: Eighty-six cases of fibrosing ILD were identified with surgical lung biopsy. Immunohistochemistry for p16 was performed on sections with the most active fibrosis. p16-positive foci (loose collection of p16-positive fibroblasts with overlying p16-positive epithelium) were identified on digital slides and quantified. Cases were scored as p16-low (≤ 2.1 foci per 100 mm2) or p16-high (> 2.1 foci per 100 mm2). Twenty-four areas including senescent foci, fibrotic and normal areas were characterized using in situ RNA expression analysis with digital spatial profiling (DSP) in selected cases. RESULTS: The presence of p16-positive foci was specific for the diagnosis of IPF, where 50% of cases expressed any level of p16 and 26% were p16-high. There was no relationship between radiographic pattern and p16 expression. However, there was increased expression of cyclin-dependent kinase inhibitors, collagens and matrix remodeling genes within p16-positive foci, and cases with high p16 expression had shorter LTx-free survival. On the other hand, antifibrotic therapy was significantly protective. DSP demonstrated that fibroblastic foci exhibit transcriptional features clearly distinct from that of normal-looking and even fibrotic areas. CONCLUSIONS: We demonstrated the potential clinical applicability of a standardized quantification of p16-positive fibroblastic foci. This method identifies an IPF phenotype associated with foci-specific upregulation of senescence-associated and matrix remodeling gene expression. While these patients have reduced LTx-free survival, good response to antifibrotic therapies was observed in those who were treated.

Validation of the risk stratification score in idiopathic pulmonary fibrosis: study protocol of a prospective, multi-centre, observational, 3-year clinical trial.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is characterized by a poor prognosis, with a progressive decline in lung function and considerable variability in the disease's natural history. Besides lung transplantation (LTx), the only available treatments are anti-fibrosing drugs, which have shown to slow down the disease course. Therefore, predicting the prognosis is of pivotal importance to avoid treatment delays, which may be fatal for patients with a high risk of progression. Previous studies showed that a multi-dimensional approach is practical and effective in the development of a reliable prognostic score for IPF. In the RIsk Stratification scorE (RISE), physiological parameters, an objective measure of patient-reported dyspnea and exercise capacity are combined to capture different domains of the complex pathophysiology of IPF. METHODS: This is an observational, multi-centre, prospective cohort study, designed to reflect common clinical practice in IPF. A development cohort and a validation cohort will be included. Patients newly diagnosed with IPF based on the ATS/ERS criteria and multi-disciplinary discussion will be included in the study. A panel of chest radiologists and lung pathologists will further assess eligibility. At the first visit (time of diagnosis), and every 4-months, MRC dyspnea score, pulmonary function tests (FEV1, FVC and DLCO), and 6-min walking distance will be recorded. Patients will be prospectively followed for 3 years. Comorbidities will be considered. The radiographic extent of fibrosis on HRCT will be recalculated at a 2-year interval. RISE, Gender-Age-Physiology, CPI and Mortality Risk Scoring System will be calculated at 4-month intervals. Longitudinal changes of each variable considered will be assessed. The primary endpoint is 3-year LTx-free survival from the time of diagnosis. Secondary endpoints include several, clinically-relevant information to ensure reproducibility of results across a wide range of disease severity and in concomitance of associated pulmonary hypertension or emphysema. DISCUSSION: The objective of this study is to validate RISE as a simple, straightforward, inexpensive and reproducible tool to guide clinical decision making in IPF, and potentially as an endpoint for future clinical trials. TRIAL REGISTRATION: U.S National Library of Medicine Clinicaltrials.gov, trial n. NCT02632123 "Validation of the risk stratification score in idiopathic pulmonary fibrosis". Date of registration: December 16th, 2015.

Pathology, Radiology, and Genetics of Interstitial Lung Disease in Patients With Shortened Telomeres.

Interstitial lung diseases (ILDs) in patients with shortened telomeres have not been well characterized. We describe demographic, radiologic, histopathologic, and molecular features, and p16 expression in patients with telomeres ≤10th percentile (shortened telomeres) and compare them to patients with telomere length >10th percentile. Lung explants, wedge biopsies, and autopsy specimens of patients with telomere testing were reviewed independently by 3 pathologists using defined parameters. High-resolution computed tomography scans were reviewed by 3 radiologists. p16-positive fibroblast foci were quantified. A multidisciplinary diagnosis was recorded. Patients with shortened telomeres (N=26) were morphologically diagnosed as usual interstitial pneumonia (UIP) (N=11, 42.3%), chronic hypersensitivity pneumonitis (N=6, 23.1%), pleuroparenchymal fibroelastosis, fibrotic nonspecific interstitial pneumonia, desquamative interstitial pneumonia (N=1, 3.8%, each), and fibrotic interstitial lung disease (fILD), not otherwise specified (N=6, 23.1%). Patients with telomeres >10th percentile (N=18) showed morphologic features of UIP (N=9, 50%), chronic hypersensitivity pneumonitis (N=3, 16.7%), fibrotic nonspecific interstitial pneumonia (N=2, 11.1%), or fILD, not otherwise specified (N=4, 22.2%). Patients with shortened telomeres had more p16-positive foci (P=0.04). The number of p16-positive foci correlated with outcome (P=0.0067). Thirty-nine percent of patients with shortened telomeres harbored telomere-related gene variants. Among 17 patients with shortened telomeres and high-resolution computed tomography features consistent with or probable UIP, 8 (47.1%) patients showed morphologic features compatible with UIP; multidisciplinary diagnosis most commonly was idiopathic pulmonary fibrosis (N=7, 41.2%) and familial pulmonary fibrosis (N=5, 29%) in these patients. In conclusion, patients with shortened telomeres have a spectrum of fILDs. They often demonstrate atypical and discordant features on pathology and radiology leading to diagnostic challenges.

Giant Cell, Giant Problems: A Case of Giant Cell Myocarditis Complicated by Cardiogenic Shock and Refractory Ventricular Tachycardia Managed With a Mechanical Circulatory Support Device.

This report reviews the management of a case of Giant Cell Myocarditis (GCM) that presented with cardiogenic shock. This case highlights the importance of a multi-disciplinary approach to the care of these patients including the use of a mechanical circulatory support (MCS) device.

Liquid biopsy is a valuable tool in the diagnosis and management of lung cancer.

Liquid biopsy refers to the use of various body fluids to test for circulating biological elements derived from the tumor. Liquid biopsy has taken on an increasingly important role in lung cancer diagnosis, molecular characterization, surveillance, monitoring, and determining mechanisms of resistance. These assays can utilize various sources of cell-free DNA (cfDNA) including blood, pleural fluid, urine, and others to detect tumor associated alterations. With the increasing power of next-generation sequencing technologies and the development of assays such as digital droplet PCR, rare tumor alleles can be detected in cfDNA to determine key characteristics of the tumor. Current assays, while effective, are still challenged by limited sensitivity and capacity to single genes or small panels of genes, though this is rapidly expanding. Nevertheless, testing of cfDNA has been shown to be valuable in detecting resistance to targeted inhibitors, particularly for detection of T790M in EGFR and monitoring response to therapy. With the continued development of more powerful and sensitive assays, these techniques will empower clinicians to better characterize early stage disease and can be used in the screening of high-risk patients, which may eliminate the requirement for tissue diagnosis in some settings. That said, since the majority of these alterations are not specific to lung cancer, there will continue to be a need for tissue in at least the initial diagnosis. Used in conjugation with tissue sampling, these assays will assist the treating clinician and the pathologist to better characterize individual tumors, even in the setting of limited tissue.

High MHC-II expression in Epstein-Barr virus-associated gastric cancers suggests that tumor cells serve an important role in antigen presentation.

EBV-associated gastric adenocarcinomas (EBVaGCs) often exhibit better clinical outcomes than EBV negative gastric cancers (GCs), which could be related to their consistent expression of foreign viral antigens. Antigen-presenting cells (APCs) present peptide antigens in the context of the class-II major histocompatibility complex (MHC-II). During inflammatory conditions, epithelial cells express MHC-II and function as accessory APCs. Utilizing RNA-seq data from nearly 400 GC patients, we determined the impact of EBV-status on expression of MHC-II components, genes involved in their regulation, and T-cell co-stimulation. Virtually all MHC-II genes were significantly upregulated in EBVaGCs compared to normal tissues, or other GC subtypes. Genes involved in antigen presentation were also significantly upregulated in EBVaGCs, as were the key MHC-II transcriptional regulators CIITA and RFX5. This was unexpected as the EBV encoded BZLF1 protein can repress CIITA transcription and is expressed in many EBVaGCs. Furthermore, MHC-II upregulation was strongly correlated with elevated intratumoral levels of interferon-gamma. In addition, expression of co-stimulatory molecules involved in T-cell activation and survival was also significantly increased in EBVaGCs. Thus, gastric adenocarcinoma cells may functionally contribute to the highly immunogenic tumor microenvironment observed in EBVaGCs via a previously unappreciated role in interferon-induced antigen presentation.