Sporadic Colorectal Cancer Research Articles

Digital spatial profiling identifies molecular changes involved in development of colitis-associated colorectal cancer.

Chronic colonic inflammation seen in inflammatory bowel disease (IBD) is a risk factor for colorectal cancer (CRC). Colitis-associated cancers (CAC) are molecularly different from sporadic CRC. This study aimed to evaluate spatially defined molecular changes associated with neoplastic progression to identify mechanisms of action and potential biomarkers for prognostication. IBD patients who had undergone colectomy for treatment of their IBD or dysplasia were identified from an institutional database. Formalin-fixed paraffin embedded samples from areas of normal, inflamed, dysplastic and adenocarcinoma tissue were identified for digital spatial profiling using the Nanostring GeoMx™ Cancer Transcriptome Atlas. RNA expression and quantification of 1812 genes was measured and analysed in a spatial context to compare differences in gene expression. Sixteen patients were included, nine patients had CAC, two had dysplasia only and five had colitis only. Significant, step-wise differences in gene expression were seen between tissue types, mainly involving progressive over-expression of collagen genes associated with stromal remodelling. Similarly, MYC over-expression was associated with neoplastic progression. Comparison of normal and inflamed tissue from patients who progressed to those who did not also showed significant differences in immune-related genes, including under-expression of thte chemokines CCL18, CCL25 and IL-R7, as well as CD3, CD6 and lysozyme. The known oncogene CD24 was significantly overexpressed. Both tissue types and patient groups are molecularly distinguishable on the basis of their gene expression patterns. Further prospective work is necessary to confirm these differences and establish their clinical significance and potential utility as biomarkers.

Functional annotation with expression validation identifies novel metastasis-relevant genes from post-GWAS risk loci in sporadic colorectal carcinomas

BackgroundColorectal cancer (CRC) is the third highest incidence cancer and is the leading cause of cancer mortality worldwide. Metastasis to distal organ is the major cause of cancer mortality. However,...

BAMLET administration via drinking water inhibits intestinal tumor development and promotes long-term health

Though new targeted therapies for colorectal cancer, which progresses from local intestinal tumors to metastatic disease, are being developed, tumor specificity remains an important problem, and side effects a major concern. Here, we show that the protein-fatty acid complex BAMLET (bovine alpha-lactalbumin made lethal to tumor cells) can act as a peroral treatment for colorectal cancer. ApcMin/+ mice, which carry mutations relevant to hereditary and sporadic human colorectal cancer, that received BAMLET in the drinking water showed long-term protection against tumor development and decreased expression of tumor growth-, migration-, metastasis- and angiogenesis-related genes. BAMLET treatment via drinking water inhibited the Wnt/β-catenin and PD-1 signaling pathways and prolonged survival without evidence of toxicity. Systemic disease in the lungs, livers, spleens, and kidneys, which accompanied tumor progression, was inhibited by BAMLET treatment. The metabolic response to BAMLET included carbohydrate and lipid metabolism, which were inhibited in tumor prone ApcMin/+ mice and weakly regulated in C57BL/6 mice, suggesting potential health benefits of peroral BAMLET administration in addition to the potent antitumor effects. Together, these findings suggest that BAMLET administration in the drinking water maintains antitumor pressure by removing emergent cancer cells and reprogramming gene expression in intestinal and extra-intestinal tissues.

Circulating metabolome landscape in Lynch syndrome.

Circulating metabolites systemically reflect cellular processes and can modulate the tissue microenvironment in complex ways, potentially impacting cancer initiation processes. Genetic background increases cancer risk in individuals with Lynch syndrome; however, not all carriers develop cancer. Various lifestyle factors can influence Lynch syndrome cancer risk, and lifestyle choices actively shape systemic metabolism, with circulating metabolites potentially serving as the mechanical link between lifestyle and cancer risk. This study aims to characterize the circulating metabolome of Lynch syndrome carriers, shedding light on the energy metabolism status in this cancer predisposition syndrome.This study consists of a three-group cross-sectional analysis to compare the circulating metabolome of cancer-free Lynch syndrome carriers, sporadic colorectal cancer (CRC) patients, and healthy non-carrier controls. We detected elevated levels of circulating cholesterol, lipids, and lipoproteins in LS carriers. Furthermore, we unveiled that Lynch syndrome carriers and CRC patients displayed similar alterations compared to healthy non-carriers in circulating amino acid and ketone body profiles. Overall, cancer-free Lynch syndrome carriers showed a unique circulating metabolome landscape.This study provides valuable insights into the systemic metabolic landscape of Lynch syndrome individuals. The findings hint at shared metabolic patterns between cancer-free Lynch syndrome carriers and CRC patients.

Distinct roles for interleukin-23 receptor signaling in regulatory T cells in sporadic and inflammation-associated carcinogenesis.

The pro-inflammatory cytokine interleukin-23 (IL-23) has been implicated in colorectal cancer (CRC). Yet, the cell-specific contributions of IL-23 receptor (IL-23R) signaling in CRC remain unknown. One of the cell types that highly expresses IL-23R are colonic regulatory T cells (Treg cells). The aim of this study was to define the contribution of Treg cell-specific IL-23R signaling in sporadic and inflammation-associated CRC. In mice, the role of IL-23R in Treg cells in colitis-associated cancer (CAC) was investigated using azoxymethane/dextran sodium sulphate in wild-type Treg cell reporter mice (WT, Foxp3 YFP-iCre), and mice harboring a Treg cell-specific deletion of IL-23 (Il23r ΔTreg). The role of IL-23R signaling in Treg cells in sporadic CRC was examined utilizing orthotopic injection of the syngeneic colon cancer cell line MC-38 submucosally into the colon/rectum of mice. The function of macrophages was studied using clodronate. Finally, single-cell RNA-seq of a previously published dataset in human sporadic cancer was reanalyzed to corroborate these findings. In CAC, Il23r ΔTreg mice had increased tumor size and increased dysplasia compared to WT mice that was associated with decreased tumor-infiltrating macrophages. In the sporadic cancer model, Il23r ΔTreg mice had increased survival and decreased tumor size compared to WT mice. Additionally, MC-38 tumors of Il23r ΔTreg mice exhibited a higher frequency of pro-inflammatory macrophages and IL-17 producing CD4+ T cells. The decreased tumor size in Il23r ΔTreg mice was macrophage-dependent. These data suggest that loss of IL-23R signaling in Treg cells permits IL-17 production by CD4+ T cells that in turn promotes pro-inflammatory macrophages to clear tumors. Finally, analysis of TCGA data and single-cell RNA-seq analysis of a previously published dataset in human sporadic cancer, revealed that IL23R was highly expressed in CRC compared to other cancers and specifically in tumor-associated Treg cells. Inflammation in colorectal carcinogenesis differs with respect to the contribution of IL-23R signaling in regulatory T cells.

Abstract B008: The polyclonal path towards malignant transformation in familial adenomatous polyposis

Abstract The widely accepted paradigm that cancer initiation is a monoclonal event has not been definitively resolved. This is largely due to the limitations of experimental systems to study cancer initiation, a definitively transient step in tumorigenesis. Individuals with familial adenomatous polyposis (FAP) possess a germline APC mutation, leading to hundreds of colonic polyps in adolescence and an eventual 100% lifetime risk of colorectal cancer. As such, total colectomies are performed once polyp burden becomes unmanageable and provide the resected colons from FAP donors provide a source of histologically normal mucosa, benign and dysplastic polyps, and, on rare occasions, adenocarcinomas, and serve as an exemplary model disease to understand human tumorigenesis. Through whole genome sequencing of 123 independent samples from six patients, we reveal the polyclonal origins of tumorigenesis in FAP. We characterize and contrast the genomic landscape and relative timing of driver mutation acquisition across normal to dysplastic and invasive colon tissue and compare this with multi-region sequencing data from sporadic colorectal cancers (CRC). We find that only early sporadic CRC drivers are common across the more heterogeneous premalignant stages. Selection, as assessed based on the ratio of nonsynonymous to synonymous mutations (dN/dS), is higher in benign than dysplastic FAP lesions and in sporadic adenomas relative to carcinomas. Phylogenetic reconstruction and pairwise sample comparisons reveal extensive heterogeneity and subclonal sharing within a patient’s benign and dysplastic lesions. Using a mechanistic mathematical model, we infer polyclonality for 90-100% of benign and 53-83% of dysplastic samples. Based on these findings, we propose a conceptual framework for the polyclonal origin of intestinal malignancies where inconsequential mutations, arising during colon formation in utero, are present across the colon and are valuable markers to uncover polyclonal ancestry. Citation Format: Ryan O. Schenck, Aziz Khan, Aaron M. Horning, Edward D. Esplin, HTAN Consortia, William J. Greenleaf, James M. Ford, Michael P. Snyder, Christina Curtis. The polyclonal path towards malignant transformation in familial adenomatous polyposis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr B008.

Beyond Time and Space: Charting Dynamic Evolution of Sporadic Colorectal Cancer

Beyond Time and Space: Charting Dynamic Evolution of Sporadic Colorectal Cancer

Possible poor prognosis in younger-onset Crohn's disease-associated anorectal cancer: A subanalysis of the Nationwide Japanese study.

Crohn's disease (CD)-associated intestinal cancers are characterized by their high incidence, particularly at the anorectal site in the Japanese population. Accumulating evidence revealed that younger-onset sporadic colorectal cancer may exhibit unique biological features. To the best of our knowledge, few previous articles reported clinicopathological features in patients with CD-associated anorectal cancer (CDAAC). Therefore, we aimed to clarify the relationship between the younger onset of cancer and clinicopathological characteristics and prognosis, and the efficacy of cancer surveillance in patients with CDAAC. CD patients who had been diagnosed with intestinal cancers from 1983 to 2020 were collected from 39 Japanese institutions in this study. Of 316 patients with CD-associated intestinal cancers, we analyzed 211 patients with CDAAC. We divided the patients into two groups according to the median age at cancer diagnosis (45 years old). Younger-onset CDAAC (YO-CDAAC) patients were significantly more likely to have a poor outcome than those with older-onset CDAAC (OO-CDAAC) in terms of both disease-free survival (DFS) (p = 0.0014) and overall survival (OS) (p = 0.023). Multivariate analysis showed that age under 45 years old at diagnosis of cancer was one of the independent factors for poor DFS and OS (hazard ratios: 2.15, 95% confidence interval: 1.09-4.26, p = 0.028, hazard ratios: 1.95, 95% confidence interval: 1.05-3.60, p = 0.033, respectively). Patients detected via surveillance showed significantly better DFS and OS rates than symptomatic patients in YO-CDAAC (p = 0.012 and 0.0031, respectively). YO-CDAAC may have a poorer prognosis compared with OO-CDAAC. Surveillance could be important to improve cancer prognosis, especially in young CD patients with anorectal disease.

Histological differentiation between sporadic and colitis-associated intestinal cancer in a nationwide study: A propensity-score-matched analysis.

Colitis-associated intestinal cancer (CAC) can develop in patients with inflammatory bowel disease; however, the malignant grade of CAC may differ from that of sporadic colorectal cancer (CRC). Therefore, we compared histological findings distinct from cancer stage between CAC and sporadic CRC to evaluate the features of CAC. We reviewed the clinical and histological data collected from a nationwide database in Japan between 1983 and 2020. Patient characteristics were compared to distinguish ulcerative colitis (UC), Crohn's disease (CD), and sporadic CRC. Comparisons were performed by using all collected data and propensity score-matched data. A total of 1077 patients with UC-CAC, 297 with CD-CAC, and 136927 with sporadic CRC were included. Although the prevalence of well or moderately differentiated adenocarcinoma (Tub1 and Tub2) decreased according to tumor progression for all diseases (P<0.01), the prevalence of other histological findings, including signet ring cell carcinoma, mucinous carcinoma, poorly differentiated adenocarcinoma, or squamous cell carcinoma, was significantly higher in CAC than in sporadic CRC. Based on propensity score-matched data for 982 patients with UC and 268 with CD, the prevalence of histological findings other than Tub1 and Tub2 was also significantly higher in those with CAC. At pT4, mucinous carcinoma occurred at a significantly higher rate in patients with CD (45/86 [52.3%]) than in those with sporadic CRC (13/88 [14.8%]) (P<0.01). CAC, including early-stage CAC, has a higher malignant grade than sporadic CRC, and this difference increases in significance with tumor progression.

Detecting microsatellite instability in colorectal cancer using Transformer-based colonoscopy image classification and retrieval.

Colorectal cancer (CRC) is a major global health concern, with microsatellite instability-high (MSI-H) being a defining characteristic of hereditary nonpolyposis colorectal cancer syndrome and affecting 15% of sporadic CRCs. Tumors with MSI-H have unique features and better prognosis compared to MSI-L and microsatellite stable (MSS) tumors. This study proposed establishing a MSI prediction model using more available and low-cost colonoscopy images instead of histopathology. The experiment utilized a database of 427 MSI-H and 1590 MSS colonoscopy images and vision Transformer (ViT) with different feature training approaches to establish the MSI prediction model. The accuracy of combining pre-trained ViT features was 84% with an area under the receiver operating characteristic curve of 0.86, which was better than that of DenseNet201 (80%, 0.80) in the experiment with support vector machine. The content-based image retrieval (CBIR) approach showed that ViT features can obtain a mean average precision of 0.81 compared to 0.79 of DenseNet201. ViT reduced the issues that occur in convolutional neural networks, including limited receptive field and gradient disappearance, and may be better at interpreting diagnostic information around tumors and surrounding tissues. By using CBIR, the presentation of similar images with the same MSI status would provide more convincing deep learning suggestions for clinical use.

P215 Mir-135b, an Early Biomarker of Sporadic and IBD-Related Colorectal Carcinogenetic Progression

Abstract Background Although the rates of IBD-related-CRC are decreasing over time, CRC is still a leading cause of mortality and reason for colectomy in patients with IBD. Among the different cancer biomarkers, microRNAs (miRs) have emerged as noninvasive tools for diagnosis, monitoring, and prognosis in tissues and biofluids of patients with IBD. Therefore, we aimed to investigate the role of miRs in the development and natural course of IBD-related CRC, in order to identify potential early biomarkers for IBD-related CRC screening and progression. Methods The cases were retrospectively collected from the archives of the Surgical Pathology and Cytopathology Unit at the University of Padua. We analysed 9 miRs in colonic tissue specimens of IBD patients with adenoma or dysplasia, with IBD related-CRC, other than 2 control groups of patients with sporadic CRC and of healthy subjects (HC). In addition, we included tissue samples from a colonoscopy that patients with IBD with adenoma or dysplasia underwent some years before the development of mucosal lesions (from 2 to 5 years before), therefore without evidence of adenoma or dysplasia. Results were analyzed with ThermoFisher Connected™ Software and a p-value &amp;lt; 0.05 was considered significant. Results Compared to HC, all nine analysed miRs were significantly up-regulated in patients with sCRC, with IBD-related CRC and in IBD patients with adenoma. While, only 3 miRs (miR-135b, mir-21, miR-224) were significantly upregulated in IBD patients with dysplasia (and in their own controls) compared to HC (p&amp;lt;0.0001). Notably, no differences in miRs expression levels were found in patients with IBD-related CRC compared to those found in patients with sCRC. Among all miRs analyzed, only miR-135b and miR-21 resulted significantly up-regulated in patients with IBD. Considering the levels of miR-135b in the tissue samples of IBD patients, we observed an evident increasing trend going from tissue specimens without lesions to those with adenoma or dysplasia and then to those with neoplastic lesions. miR-21 was significantly upregulated in patients with IBD-related CRC compared to both IBD patients with adenoma and their own control samples from a previous negative colonoscopy (p=0.003 and p=0.006, respectively). Likewise, a significant difference in miR-21 levels was observed between patients with IBD-related CRC and those with dysplasia (p=0.02). Conclusion miR-21 and miR-135b are involved in the carcinogenesis process of patients with IBD. They could be potential candidate biomarkers for diagnostic purpose, prognostic and predictive stratification of patients.

P453 Surveillance for colorectal dysplasia and neoplasia in Latin American patients with Ulcerative Colitis

Abstract Background colorectal cancer (CRC) in patients with inflammatory bowel disease (IBD) has worse prognostic features and a higher mortality rate compared to sporadic CRC. Screening colonoscopy is therefore an important tool to consider in this population. The aim of this study is to describe the findings of endoscopic surveillance of CRC in patients with IBD using the technology available in Latin American countries. Methods Descriptive, multicentre, cross-sectional, descriptive study conducted in multiple Latin American countries in patients with ulcerative colitis (UC) more than 8 years after diagnosis and ulcerative colitis with primary sclerosing cholangitis regardless of the time of diagnosis of colitis. Surveillance colonoscopies were performed according to the availability of technology in each country. Results 78 subjects, 50% women, from 5 countries (Colombia, Costa Rica, Peru, Ecuador, and Dominican Republic), with mean age 47.9 (range 20.01-89.71; SD 151.4) years, mean age at disease diagnosis of 34.7 (range 8.52-80.9; SD 14.08) years, and mean time of disease of 12.8 (range 4.6-56.8; SD 8.9) years. 57.7% (45/78) with extensive colitis, 8.9% (7/78) with a family history of colorectal cancer. 52.6% (41/78) on biologic therapy. 24.4% (19/78) current use of Azathioprine. 9% (7/78) of corticosteroids. 70.5% (55/78) oral mesalazine. In 5.1% it was used white light, 1.3% high resolution white light, 76.9% digital chromoendoscopy and 16.7% chromoendoscopy with staining. In those with digital chromoendoscopy, NBI was used in 38.3% (28/73), 37% (27/73) LCI/BLI, and 24.6% (14/73) I-Scan. It was found pseudopolyps in 50% (39/78), and 11.5% (9/78) stenosis. 7.7% (6/78) had a history of previous dysplasia. Regarding the Paris classification modified by SCENIC consensus, 28.2% (22/78) found 0-I lesions, 16 subjects were 0-I s, and 6 subjects 0-Ip. 5 subjects had 0-II lesions, of which 4 subjects in 0-IIa, and 1 in 0-IIc. 1 subject had lesion type 0-III. 1 subject had mixed lesions (0-IIa+0-IIc), 6.4% (5/78) lesion with ulceration, 10.2% (8/78) with disruption of lesion borders, with KUDO classification, Kudo III, 5.1 (4/78) Kudo IV and 3.8% (3/78) Kudo V. Endoscopic resectability was possible in all lesions. Histological findings were: (11/78) low grade dysplasia, (1/78) high grade dysplasia and (3/78) adenocarcinoma. As for the presence of dysplasia not visible in white light in random biopsies, it was only detected in (2/78). Conclusion in this first Latin American study, endoscopic techniques with digital chromoendoscopy with targeted biopsies were preferred, most were endoscopically visible and resectable lesions suggesting that the yield of targeted biopsies is superior to random biopsies.

BRAF variants and oncogenic fusions to define sporadic MMR-deficient colorectal cancer subtypes.

211 Background: Mismatch-repair deficient (MMRd) colorectal cancers (CRC) are rare tumors exquisitely sensitive to immunotherapy. The molecular events that initiate and sustain MMRd tumors remain controversial. The majority of sporadic MMRd CRCs exhibit BRAF-V600E variants with MLH1 hypermethylation, however BRAF-wild-type(wt) tumors exhibit high rates of rare gene fusions. Methods: We performed an integrated molecular and clinical analysis for 253 patients with MMRd sporadic CRC who received MSK-IMPACT genomic profiling at Memorial Sloan Kettering Cancer Center. Tumors were classified based on BRAF-V600E variants and gene fusion events. We evaluated the tumor burden of molecular alterations and disproportionate co-occurrence of specific driver variants of significance between each subtype. We used allele-specific FACETS analysis and MLH1 promoter hypermethylation assessments to infer the MMR-gene inactivation mechanism per tumor. We also examined differences in tumor phenotype and patient clinical outcomes. Patient progression-free-survival after treatment and overall survival was assessed with the Kaplan-Meier curves, and multivariable analyses were performed with Cox proportional hazards regression modeling. Results: Patients exhibited BRAF-V600E-mutated (mut: n=178), BRAF-V600E-wt/gene-fusion positive (n=42), and BRAF-V600E-wt/fusion-negative (n=33) disease. Gene fusion events were mutually exclusive with BRAF-V600E variants and occurred in NTRK1 (n=13), NTRK3 (n=8; one with co-occurring NTRK1 fusion), RET (n=8), BRAF (n=8), ALK (n=5), and FGFR2 (n=1). BRAF-V600E-mut and fusion-positive tumors display similar predominant MLH1 silencing, WNT-signaling activators, and co-alterations. In contrast, BRAF-V600E-wt/fusion-negative tumors exhibit MLH1 inactivation associated with increased copy number alterations, and exhibit distinct co-occurring APC and TCFF7L2 variants. Both fusion-positive and BRAF-V600E-wt/fusion-negative tumors disproportionately arise in the transverse and left colon. In a multivariable analysis of 73 patients with stage IV MMRd CRC, fusion-positive status was an independently-significant, positive prognostic marker. For patients treated with immune checkpoint inhibitors (ICIs), tumor regression rates were high in BRAF-V600E-mut (63%; n=22/35) and fusion-positive (62.5%, n=5/8) subtypes, with slightly poorer outcomes in BRAF-V600E-wt/fusion-negative (40%, n=2/5) tumors. Patients with fusion-positive tumors exhibited clinical benefit to NTRK inhibition. Conclusions: In sporadic MMRd CRC, gene fusion-positive tumors exhibit an improved prognosis with similar molecular and treatment outcomes to BRAF-V600E-mut tumors. BRAF-V600E-wt/fusion-negative tumors are a unique sporadic MMRd subtype driven by alternative WNT-activation and potentially lower immunotherapy responses in small numbers of patients.

Comparative genomic analysis to identify a signature of sporadic colorectal cancer development in young adults.

208 Background: Young-onset sporadic CRC is an important yet understudied heterogeneous group of aggressive cancers with distinct clinical and histopathological features. There is a steady increase in the incidence of cancer in this group of patients and currently, there are no screening guidelines to identify these patients due to a lack of understanding of the molecular mechanisms driving cancer in this patient group. Introduction: Despite screening guidelines and recent advances in cancer treatment, colorectal cancer (CRC) remains the second most diagnosed cancer and the second and third leading cause of cancer-related mortality in Canadian men and women, respectively [Canadian Cancer Statistics 2017.]. More striking is the rise in incidence of CRC in young adults in the United States [Siegel, R.L., et al, Bailey, C.E., et al., Dozois, E.J., et al., Deen, K.I., et al.], and the expectation that by the year 2030, the incidence rate will increase by 90% in this patient population. Data from the Surveillance and Cancer registry at Cancer Care Ontario shows a similar trend with increased rates in younger adults (ages 30 to 49) by 5.2 per cent per year between 2005 and 2012 [Ontario, C.C., Cancer Fact.]. Moreover, these younger patient groups are often diagnosed with aggressive forms and advanced stages of the disease [Ontario, C.C., Cancer Fact.]. Methods: In this study, using a total of 30 colorectal cancer patient samples from Windsor Regional Hospital Cancer Program, we performed comprehensive targeted gene sequencing to identify single nucleotide variants, small insertions/deletions, copy number variants in over 500 genes that are implicated in cancer. Mean age of the patients in this study was 44 years and only patients without any personal or family history of colon cancer /other malignancies or IBD were enrolled in the study. Results: While identifying previously known colorectal cancer associated genetic variants, our preliminary data shows distinct missense mutations in several genes potentially contributing to the development and progression of cancer in these patients. In addition to showing pathogenic mutations in colorectal cancers associated genes, such as PIK3CA (H1047R, E545K, E545G, R93W, V344A), KRAS (G12V, G12D, A146T) and APC, our study showed recurring missense mutations in several genes including AXIN2, ALK, CDKN1A, MAP3K1, ROS1, EPCAM, KDM5A and AURKA in over 50% of our samples. Conclusions: The genomic profiling performed using biopsies from young colorectal cancer patients through this study provides a unique ability to identify the potential “genomic triggers” for the development and progression of cancer in young sporadic colorectal cancer patients. This information can not only be used to develop targeted treatment options for these patients but also to design new screening protocols as well as optimal surveillance strategies.

Clinical characteristics and outcomes of patients with metastatic colitis-associated cancer treated with EGFR inhibitors.

37 Background: Colitis-associated cancer (CAC) is a devastating complication of inflammatory bowel disease. CAC tumor biology differs from that of sporadic colorectal cancer (CRC). Patients (pts) with (w/) metastatic CAC (mCAC) treated w/ 1st line (1L) chemotherapy have worse outcomes than pts w/ sporadic metastatic CRC (mCRC). EGFR inhibitor (EGFRi) w/ chemotherapy is standard of care for mCRC that is left (L) sided, RAS wild type (WT), without BRAF V600E mutation (mut) or ERBB2 amplification (amp). There are no published data on efficacy of EGFRi in CAC. We report outcomes of mCAC pts treated w/ EGFRi. Methods: Cases were identified by querying a prospectively maintained database of CAC pts seen at Memorial Sloan Kettering Cancer Center from 1/2000-present. Among mCAC pts who received EGFRi (n = 16), outcomes of interest: best response, progression-free survival (PFS), and overall survival (OS). PFS was calculated from date of 1st treatment w/ EGFRi until progression or death. OS was calculated from date of 1st treatment w/ EGFRi until death or last follow-up. Survival analyses were performed using Kaplan-Meier method. Data were obtained through review of electronic medical records. Results: 84 pts w/ mCAC were identified (52 L sided, 24 right [R] sided, 8 small bowel). Genomics were consistent w/ our prior reports: 79% TP53 mut, 19% APC mut, 14% MYC amp/gain, 32% KRAS mut, 4% BRAF mut, 6% ERBB2 amp. Limiting to pts w/ tumors that were L sided, RAS WT, without BRAF V600E mut or ERBB2 amp, we identified 34 (40%) mCAC pts. 16 (47%) of these pts received EGFRi as 2L or 3L therapy. 3 pts (19%) received EGFRi alone, 13 pts (81%) received EGFRi w/ FOLFIRI or irinotecan. 8 pts (50%) had tumors that were high grade and/or w/ signet ring features. Metastatic sites at initiation of EGFRi: lymph node (69%), liver (50%), lung (50%), peritoneum (38%), bone (38%), soft tissue (38%). 2 pts (12.5%, 95% CI: 1.5-38.3%) had a response, 4 pts (25%) had stable disease (SD), and 10 pts (62.5%) had progressive disease (PD) as best response. Median PFS and OS: 3.0 months (95% CI: 1.8-8.7) and 11.5 months (95% CI: 8.8-17.4), respectively. 2 additional pts w/ R sided CAC received EGFRi w/ SD and PD as best responses. Conclusions: Pts w/ mCAC, who by established criteria are eligible for treatment w/ EGFRi, have rapid progression and low response rates to EGFRi. This suggests that unlike sporadic CRC, CAC may not be driven primarily by EGFR. Many had high grade histology and unusual sites of metastases (bone, soft tissue). Experiments are under way to elucidate mechanisms underlying resistance to EGFRi and will be reported. These include immunohistochemistry for EGFR and its ligands, transcriptomic analyses to classify consensus molecular subtypes, and assessment of EGF dependence and EGFRi sensitivity in CAC organoids.

Retrospective review of compliance with guideline-directed germline testing in microsatellite instability-high colorectal cancer treated at the Veterans Health Administration.

86 Background: Lynch syndrome (LS) is an autosomal dominant inherited cancer syndrome that confers an increased risk of colorectal cancer (CRC). As clinical and history features under-recognize LS cases (3-5% of CRC), universal screening of CRCs for LS is recommended. Patients whose CRCs are mismatch repair protein deficient (dMMR) and/or microsatellite instability high (MSI-H) are recommended to have subsequent genetics evaluation to screen for germline mutations. Confirmed LS changes cancer surveillance recommendations for affected patients and their relatives. Within Veterans Health Administration (VHA), GT is ordered by genetic counselors at genomic medicine telehealth centers (GMTC), after initial consultation. We aim to quantify rates at which CRC patients treated at the VHA complete germline testing (GT) when indicated. Methods: The electronic health records (EHRs) of VHA patients with known dMMR/MSI-H CRC were reviewed. Cases were extracted from both Veterans Affairs (VA) Puget Sound and referral VA MSI testing laboratories. Surgical pathology reports and clinical documentation were reviewed in Joint Longitudinal Viewer (JLV) to determine if GT was indicated and reason for non-testing, if not performed. Patients with known LS prior to development of CRC were excluded, and patients with dMMR in MLH1 or MSI-H with concurrent BRAFV600 mutation and/or MLH1 hypermethylation were considered to have sporadic CRC. Results: Of 110 patients with abnormal tumor LS screening; 39 (36%) patients’ tumor tissue underwent IHC for dMMR, 16 (14%) underwent PCR for MSI, and 55 (50%) had both. 45 (41%) patients were classified as somatic MSI-H. 65 (59%) patients met criteria for referral for GMTC and GT. Of these 65, 49 ultimately did not undergo GT and 16 did, which confirmed 4 cases of LS and revealed 1 variant of uncertain significance in the MLH1 gene. Reasons for non-testing were: 7 (14%) declined all cancer testing and treatment after CRC diagnosis or were lost to follow-up/declined establishment of cancer care, 3 (6%) declined referral to GMTC, 14 (29%) accepted referral to GMTC but never had consultation, 7 (14%) accepted referral to GMTC but declined GT when offered, and 18 (37%) were never offered GMTC referral or GT. Conclusions: A majority of dMMR/MSI-H cases with an indication for GT were referred for genetic counseling, but only a small subset completed testing. This analysis identified multiple areas for improvement, including a lack of recognition by providers for the need for GT, and lack of completion of testing by patients at multiple levels. Further evaluation of VHA-specific barriers is needed to improve the quality of delivered care.

Comparison of the disease presentation of early- vs. later-onset colorectal cancer within the prospective ColoCare study.

91 Background: Within the United States (US), colorectal cancer (CRC) is the third most diagnosed cancer and the second leading cause of cancer-related fatalities, with a median age at diagnosis of 66 years. While the incidence of sporadic CRC is decreasing, the incidence in those aged 18-49 years has steadily increased. Younger patients are not often screened for CRC, and they are often diagnosed at a later stage of disease. Herein, we compare the presenting symptoms and stage at diagnosis of early-onset CRC to disease in those aged 50 or greater. Methods: The ColoCare Study is a prospective cohort enrolling individuals diagnosed with primary CRC across six cancer centers in the US and one site in Germany. Serial questionnaires administered at baseline assessed demographic characteristics and symptoms experienced prior to diagnosis, while clinical data such as staging and pathology were abstracted from medical records. For this analysis, only patients who had available age and tumor stage were included. Patients diagnosed &lt;50 years old were categorized as “early-onset” and ≥50 as “later-onset.” Fisher’s exact test was used to compare demographics, disease state characteristics, and symptoms experienced by age group. Statistical significance was based on a two-sided alpha level of 0.05. Results: 1,996 patients were included in this analysis. Of these, 1,508 (76%) were later-onset (mean diagnosis age 64, range: 50-94), while 488 (24%) were early-onset (mean age: 42, range: 21-49). Demographic data was similar between early- and later-onset patients in terms of gender and primary site. Disease stage at diagnosis was significantly associated with age (p &lt; 0.001). A higher proportion of early-onset patients had advanced disease at the time of diagnosis compared to later-onset for both stage III (43% vs 37%) and stage IV disease (28% vs 17%). For patients with available histologic data, younger patients were more likely to have vascular (35% vs 28%, p=0.03) and perineural invasion (33% vs 21%, p &lt;0.001) at diagnosis. Early-onset patients were also more likely to report symptoms prior to diagnosis (95% vs 83%, p &lt;0.001). Specifically, younger patients reported higher rates of abdominal pain (46% vs 23%, p &lt; 0.001), blood in stool (71% vs 54%, p &lt;0.001), and changes in bowel habits (54% vs 40%, p &lt;0.001). General weakness and vomiting were also statistically more likely to be noted at presentation in early-onset patients. Conclusions: In this prospective real-world cohort analysis, patients with early-onset CRC are more likely to be diagnosed with more advanced disease at presentation than later-onset patients. This analysis highlights key symptoms that should raise awareness as possible indicators of a new diagnosis of CRC, even in individuals &lt;50 years old. Additional disease comparisons between age groups will be presented at the meeting.

Genomic alteration in sporadic adolescent and young adult-onset colorectal adenocarcinoma.

154 Background: Colorectal cancer (CRC) incidence is increasing in adults younger than 50 years. This study evaluated genomic alteration in adolescent and young adult (AYA)-onset sporadic CRC patients who aged between 15 and 39 years. Methods: DNA from 90 archived formalin-fixed, paraffin-embedded (FFPE) tissue samples that histologically confirmed adenocarcinoma with proficient mismatch repair tumors at Siriraj Hospital (Bangkok, Thailand) were extracted. Patients who clinically suspected familial adenomatous polyposis were excluded. Gene mutational analysis was performed by next-generation sequencing (NGS) using an Oncomine Comprehensive Assay Plus kit (Thermo Fisher Scientific, Inc., Waltham, MA, USA) and compared with previous reported molecular data in adult-onset CRC from our group. Results: The top 5 mutations frequency observed were TP53, KRAS, FBXW7, PIK3CA, and SMAD4 mutations which were comparable to what reported in adult-onset CRC. However, FBXW7, PIK3CA, NOTCH1, FGFR3, ERBB2, and PTEN were reported more frequent in AYA group. No difference in number of KRAS, NRAS, and BRAF mutations among 2 groups. Table below shows key cancer genes mutation frequencies. Conclusions: This study is the comprehensive report hotspot mutations using NGS in sporadic AYA-onset sporadic CRC patients. The most commonly identified gene mutation frequencies among AYA-onset were similar to those reported in adult-onset, except for FBXW7, PIK3CA, NOTCH1, FGFR3, ERBB2, and PTEN mutations that had a slightly higher frequency. Further studies on larger sample set for genetic and epigenetic landscape are required. [Table: see text]

Matrix metalloproteinases as biomarkers and therapeutic targets in colitis-associated cancer.

Colorectal cancer (CRC) remains a major cause of morbidity and mortality. Therapeutic approaches for advanced CRC are limited and rarely provide long-term benefit. Enzymes comprising the 24-member matrix metalloproteinase (MMP) family of zinc- and calcium-dependent endopeptidases are key players in extracellular matrix degradation, a requirement for colon tumor expansion, invasion, and metastasis; hence, MMPs are an important research focus. Compared to sporadic CRC, less is known regarding the molecular mechanisms and the role of MMPs in the development and progression of colitis-associated cancer (CAC) - CRC on a background of chronic inflammatory bowel disease (IBD) - primarily ulcerative colitis and Crohn's disease. Hence, the potential of MMPs as biomarkers and therapeutic targets for CAC is uncertain. Our goal was to review data regarding the role of MMPs in the development and progression of CAC. We sought to identify promising prognostic and therapeutic opportunities and novel lines of investigation. A key observation is that since MMPs may be more active in early phases of CAC, using MMPs as biomarkers of advancing neoplasia and as potential therapeutic targets for adjuvant therapy in those with advanced stage primary CAC rather than overt metastases may yield more favorable outcomes.

High iNOS and IL-1β immunoreactivity are features of colitis-associated colorectal cancer tumors, but fail to predict 5-year survival.

Inflammatory bowel disease (IBD; mainly ulcerative colitis and Crohn's disease) is associated with the development of colorectal cancer (CRC) referred to as colitis-associated colorectal cancer (CAC). In inflammatory flares of IBD, the production of luminal nitric oxide (NO) increases due to the increased inducible nitric oxide synthase (iNOS) activity in inflamed tissue. It is believed that iNOS parallels pro-inflammatory interleukin-1β (IL-1β). How these biomarkers relate to CAC pathogenesis or survival is unknown. The primary aim of this study was to investigate iNOS and IL-1β immunoreactivity in CAC tumors in comparison with CRC and normal colonic mucosa, and the secondary aim was to determine if immunoreactivity correlates with 5-year survival of CAC. Immunohistochemistry was performed on tissue sections as follows: CAC (n = 59); sporadic CRC (sCRC) (n = 12); colonic mucosa >2 cm outside sCRC margin (normal mucosa) (n = 22); paracancerous IBD (pIBD) (n = 12). The expression of iNOS and IL-1β was quantified separately for epithelium and stroma. Data were evaluated using the Mann-Whitney U-test and the log-rank test for 5-year Kaplan-Meier survival curves. Results were compared with online mRNA databases. Immunoreactivity occurred predominantly in epithelial cells and to lesser extent in stroma. Compared with normal mucosa, immunoreactivity for iNOS (P < 0.01) and IL-1β (P < 0.005) was higher in CAC epithelium. In CAC stroma, iNOS immunoreactivity was lower than normal mucosa (P < 0.001), whereas IL-1β was higher (P < 0.05). Immunoreactivity differences of iNOS or IL-1β among CAC patients failed to correlate with 5-year survival. These findings were supported by online mRNA databases. Consistent with high NO production in IBD, there is more iNOS in CAC epithelium, albeit not in stroma. This immunoreactivity difference exists for IL-1β in both epithelium and stroma. The intervention of arginine or iNOS activity for CAC chemotherapy is not straightforward.