Pai, Rish

3525 Background: Tumor microenvironment (TME) features of colorectal cancer (CRC) may influence detection of circulating tumor DNA (ctDNA) and further refine prognosis. We applied a deep learning histopathologic algorithm to quantify TME features in stage III colon cancers and evaluated their association with postoperative ctDNA status among participants in a phase III FOLFOX-based adjuvant trial (NCCTG N0147). Methods: QuantCRC (Aiforia Technologies) was applied to digitized hematoxylin and eosin-stained whole-slide images of stage III colon adenocarcinomas to extract quantitative histopathologic features. Among cases where data met quality control (N=1817), associations between 15 distinct pathologist-defined features and clinical outcomes—time to recurrence (TTR), disease-free survival (DFS), and overall survival (OS)—were evaluated, stratified by postoperative ctDNA status assessed by a tissue-free assay (Guardant Reveal). Relationships were analyzed using univariate and multivariable Cox proportional hazards models that were adjusted for clinicopathologic and molecular features ( KRAS , BRAF V600E , MMR status). Interaction testing was performed. Results: We found statistically significant quantitative differences for histopathological features by ctDNA status. Features associated with ctDNA positivity(+) included lymphovascular invasion (LVI), and increased %high grade, %tumor budding, %necrosis, and %stroma. ctDNA+ cases had lower %inflammatory stroma and fewer %signet ring cells (all p< 0.006). Multivariable analyses, irrespective of ctDNA status, identified %tumor budding, %mucin, %signet ring cells, %inflammatory tumor bed, and %inflammatory stroma as significantly associated with adverse outcomes (TTR, DFS, OS). Within ctDNA+ cases, higher %immature tumor bed was associated with adverse outcome for all 3 variables. Among ctDNA-negative cases, significantly poorer outcomes (TTR, DFS, OS) were observed for tumors with lower tumor infiltrating lymphocyte (TIL) density and reduced %necrosis. After adjustment, significant interactions with ctDNA status were observed for LVI (p< 0.006) and %signet ring cells (p< 0.035) across all outcome variables, for %necrosis with DFS, OS (p<0.040), and for TILs with TTR (p<0.015). Analysis is ongoing for ctDNA tumor fraction as well as tumor genotyping data (739 genes; Guardant360). Conclusions: QuantCRC identifies TME features associated with postoperative ctDNA status that enable risk-stratification within ctDNA groups. Among ctDNA-negative patients, reduced intratumoral TIL density and reduced tumor necrosis identify high-risk subgroups with inferior clinical outcomes, and may have clinical utility.

93 Background: Colorectal cancer (CRC) is the 4th most common cancer among men and women and roughly 2-4% of all CRCs occur in patients with a diagnosis of Lynch syndrome (LS), an autosomal dominant condition found to be the most common cause of hereditary CRC with estimated lifetime risk of developing CRC between 50-80%. LS results from mutations in one or more of 5 genes: MLH1, MSH2, MSH6, PMS2, and EPCAM, which lead to a deficiency in DNA mismatch repair ( dMMR ). Current guidelines suggest testing every CRC for microsatellite instability ( MSI ) or MMR gene expression using immunohistochemistry (IHC) to identify LS-related CRC. QuantCRC is a prognostic AI model that identifies important histological features of CRC and provides a recurrence prediction estimate useful for treatment decisions. It uses computational image analysis to extract quantitative features from digitized H&E stained pathology slides such as tumor grade, tumor-infiltrating lymphocytes, and other morphometric parameters. 4 It has been verified and validated in Aiforia (AI for image analysis) Platform using whole slide images and against reviews by independent pathologists from 8 hospitals. Our study sought to use QuantCRC to identify histological differences between those with MSI (confirmed LS), sporadic MSI , and microsatellite stability (MSS ) CRC to better help clinicians identify which patients would benefit from additional testing. Methods: We conducted a retrospective cohort study of patients with CRC whose pathology was analyzed at Mayo Clinic Arizona. Tumor characteristics were analyzed by QuantCRC and Receiver Operating Characteristic (ROC) curve analysis using Area Under the Curve (AUC) was used to see if QuantCRC could distinguish CRCs with MSI or LS. Results: Of the total 5132 patients with CRC, 1101 (21.5%) samples were MSI/dMMR with 468 (42.5%) of those having confirmed LS. The study had roughly equal parts men and there were more women with non-LS MSI (59%) than with LS or microsatellite stability. The QuantCRC model’s ROC analysis revealed an AUC of 0.83 for predicting MSI/dMMR among all patients with a sensitivity of 0.75 and a specificity of 0.79. AUC for predicting LS among all patients was 0.76 and of predicting LS among MSI/dMMR was 0.64. Conclusions: The QuantCRC model was useful in predicting MSI/dMMR status among all patients with CRC. It can be a helpful clinical tool when assessing which patients may benefit from additional genetic or IHC testing, especially in lower resource areas where molecular testing may be difficult to access or expensive relative to an H&E slide.

PURPOSE Pancreatic acinar cell carcinoma (PACC) is a rare and aggressive form of pancreatic cancer that originates in the acinar cells of the exocrine pancreas. In this study, we aimed to investigate the clinical and molecular characteristics of patients with PACC at our institution. METHODS This was a retrospective study of patients with PACC seen at Mayo Clinic between 2002 and 2023. Baseline patient characteristics, tumor pathology, treatment strategies used, and survival outcomes were analyzed. Kaplan-Meier curves were estimated using newsurv macros in SAS. RESULTS The study included a total of 65 patients with PACC. The median age at diagnosis was 66 years. Almost half of the patients (48%) presented with resectable/borderline-resectable disease (n = 28). Five-year overall survival (OS) for resectable/borderline-resectable, locally advanced/unresectable, and metastatic disease were 72.0%, 21.6%, and 20.9%, respectively. Somatic and germline next-generation sequencing identified numerous potentially actionable targets including homologous recombination (43% somatic, 33% germline), RAF alterations (29% somatic), and mismatch repair (14% somatic). CONCLUSION Our findings underscore the heterogeneity and aggressive nature of PACC. Despite the improved prognosis for patients with resectable/borderline-resectable disease, OS remains poor, particularly for those with locally advanced or metastatic disease. The identification of actionable molecular targets in a significant proportion of patients highlights the potential for personalized therapeutic approaches. Future research should focus on tailored treatment strategies to exploit these molecular vulnerabilities, which may offer new options for improving outcomes in this rare malignancy.

ABSTRACT A 70-year-old man presented to the clinic with a 6-month history of dysgeusia, followed by chronic, non-bloody diarrhea and 45 lb unintentional weight loss. Esophagogastroduodenoscopy discovered confluent nodularity in the gastric antrum and examined duodenum, but a normal esophagus. Colonoscopy uncovered patches of polypoid nodular mucosa throughout the entire colon. Biopsies of the nodular mucosa were consistent with hamartomatous polyps while biopsies of the intervening, normal-appearing mucosa demonstrated edema with crypt architectural distortion. Other hereditary polyposis syndromes were excluded with genetic testing, confirming a diagnosis of Cronkhite-Canada syndrome. Adalimumab therapy was initiated with clinical improvement after nonresponse to prednisone.

Abstract Background People with cancer experience high rates of venous thromboembolism (VTE). Risk of subsequent cancer is also increased in people experiencing their first VTE. The causal mechanisms underlying this association are not completely understood, and it is unknown whether VTE is itself a risk factor for cancer. Methods We used data from large genome-wide association study meta-analyses to perform bidirectional Mendelian randomization analyses to estimate causal associations between genetic liability to VTE and risk of 18 different cancers. Results We found no conclusive evidence that genetic liability to VTE was causally associated with an increased incidence of cancer, or vice versa. We observed an association between liability to VTE and pancreatic cancer risk [odds ratio for pancreatic cancer: 1.23 (95% confidence interval: 1.08–1.40) per log-odds increase in VTE risk, P = 0.002]. However, sensitivity analyses revealed this association was predominantly driven by a variant proxying non-O blood group, with inadequate evidence to suggest a causal relationship. Conclusions These findings do not support the hypothesis that genetic liability to VTE is a cause of cancer. Existing observational epidemiological associations between VTE and cancer are therefore more likely to be driven by pathophysiological changes which occur in the setting of active cancer and anti-cancer treatments. Further work is required to explore and synthesize evidence for these mechanisms.

Validated nonbiopsy methods to assure duodenal mucosal healing in celiac disease are lacking, yet ongoing mucosal injury is associated with anemia, osteoporosis, and lymphoma. Most providers utilize clinical data as surrogates of mucosal status to avoid additional esophagogastroduodenoscopy. The reliability of such surrogates to predict mucosal recovery has been incompletely evaluated. The aim of this study was to rigorously assess patterns of histologic mucosal recovery at follow-up in celiac disease and to correlate findings with clinical data. Gastrointestinal pathologists from 13 centers evaluated initial and follow-up duodenal biopsies from 181 celiac disease patients. Marsh scores and intraepithelial lymphocytes (IELs)/100 enterocytes were assessed blindly. Histology at follow-up was correlated with symptoms, immunoglobulin A anti–tissue transglutaminase titers and gluten-free diet adherence. Fifty-six/181 (31%) patients had persistent villous blunting and 46/181 (25%) patients had just persistently elevated IELs at follow-up, with only 79/181 (44%) patients having complete histologic remission. IEL normalization (82/181; 45%) lagged villous recovery (125/181;69%). In a minority of patients, villous blunting was limited to proximal duodenal biopsies. No correlation was found between Marsh scores and symptoms, normalization of immunoglobulin A anti–tissue transglutaminase serology, or diet adherence. Children showed greater recovery of Marsh score (P<0.001) and IELs (P<0.01) than adults. Persistent mucosal injury is common in celiac disease, with discordant villous/IEL normalization. Pathologist awareness of expected findings in celiac disease follow-up biopsies, including their frequent lack of correlation with clinical data, is important for patient management, and has implications for eligibility criteria for therapeutics currently in development.

Drug induced liver injury is a very frequent cause of hepatotoxicity and within that group, herbal and dietary supplements are a well described subcategory. The following clinical vignette describes the case of a young man with acute hepatitis secondary to the use of Ilex paraguariensis, also known as yerba mate, which is a herbal product commonly drunk in South America. This is the first written case of mate tea induced hepatotoxicity.