Lynch Syndrome Carriers Research Articles

Abstract B058: Nous-209 off-the-shelf vaccine targets neoantigens mutations well represented both in primary and metachronous incident CRCs from Lynch syndrome patients

Abstract Lynch Syndrome (LS) is the most common hereditary cancer syndrome, caused by germline mutations in one of the four DNA mismatch repair (MMR) genes. LS patients have a high risk to develop microsatellite instable (MSI) colorectal cancers. Tumors developed by LS carriers display high levels of microsatellite instability, which leads to the accumulation of large numbers of mutations, among which frameshift insertion/deletions (indels) within microsatellite (MS) loci are very common and shared among different tumors. When indels occur in coding genes they give rise to frameshift peptides (FSPs) with a very high potential to act as safe and potent neoantigens for a vaccine. NOUS-209 is a genetic vaccine encoding 209 neoantigens, shared across sporadic and hereditary MSI tumors, developed for interception and treatment of MSI tumors. Phase 1b trial evaluating NOUS-209 monotherapy in healthy LS carriers showed the induction of a potent and broad immune response. Here, we characterize indels encoding FSPs in a cohort of 50 incident MSI CRC from LS patients detected during routine screening (38 primary tumors; 22 metachronous tumors) by whole Exomeseq NGS. Overall, primary and metachronous tumors have a similar number of indels in coding genes. The repertoire of detected indels is only partially shared (27%) between the two categories of tumors. The 209 indels selected for the NOUS-209 vaccine are instead highly shared (95%) between primary and metachronous tumors. Moreover, the analysis of 8 patients for which both the primary and the metachronous tumor were available confirmed the presence of the 209 mutations both in the first and the second tumor. Therefore, the NOUS 209 vaccine has the potential to prevent tumor occurrence both in previvors and survivors by inducing a broad T cell immune response against recurrent FSP. Citation Format: Lorenzo De Marco, Elisa Micarelli, Joni Panula, Anna Morena D'Alise, Guido Leoni, Kalle E. Hokkanen, Eija Hämäläinen, Jukka-Pekka Mecklin, Elisa Scarselli, Toni Seppälä. Nous-209 off-the-shelf vaccine targets neoantigens mutations well represented both in primary and metachronous incident CRCs from Lynch syndrome patients [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr B058.

Influence of Genetic Polymorphisms on the Age at Cancer Diagnosis in a Homogenous Lynch Syndrome Cohort of Individuals Carrying the MLH1:c.1528C>T South African Founder Variant.

Background: High variability in the age at cancer diagnosis in Lynch syndrome (LS) patients is widely observed, even among relatives with the same germline pathogenic variant (PV) in the mismatch repair (MMR) genes. Genetic polymorphisms and lifestyle factors are thought to contribute to this variability. We investigated the influence of previously reported genetic polymorphisms on the age at cancer diagnosis in a homogenous LS cohort with a South African founder germline PV c.1528C>T in the MLH1 gene. Methods: A total of 359 LS variant heterozygotes (LSVH) from 60 different families were genotyped for specific genetic polymorphisms in GSTM1, GSTT1, CYP1A1, CYP17, PPP2R2B, KIF20A, TGFB1, XRCC5, TNF, BCL2, CHFR, CDC25C, ATM, TTC28, CDC25C, HFE, and hTERT genes using Multiplex Polymerase Chain Reaction and MassArray methods. Kaplan-Meier survival analysis, univariate and multivariate Cox proportional hazards gamma shared frailty models adjusted for sex were used to estimate the association between age at cancer diagnosis and polymorphism genotypes. A p-value < 0.05 after correcting for multiple testing using the Benjamini-Hochberg method was considered significant at a 95% confidence interval. Results: We identified three genotypes in the cell-cycle regulation, DNA repair, and xenobiotic-metabolism genes significantly associated with age at cancer diagnosis in this cohort. The CYP1A1 rs4646903 risk (GG) and CDC25C rs3734166 polymorphic (GA+AA) genotypes were significantly associated with an increased risk of a younger age at cancer diagnosis (Adj HR: 2.03 [1.01-4.08], p = 0.034 and Adj HR: 1.53 [1.09-2.14], p = 0.015, respectively). LSVH who were heterozygous for the XRCC5 rs1051685 SNP showed significant protection against younger age at cancer diagnosis (Adj HR: 0.69 [CI, 0.48-0.99], p = 0.043). The risk of a younger age at any cancer diagnosis was significantly high in LS carriers of one to two risk genotypes (Adj HR: 1.49 [CI: 1.06-2.09], corrected p = 0.030), while having one to two protective genotypes significantly reduced the risk of developing any cancer and CRC at a younger age (Adj HR: 0.52 [CI: 0.37-0.73], and Adj HR: 0.51 [CI: 0.36-0.74], both corrected p < 0.001). Conclusions: Polymorphism genotypes in the cell-cycle regulation, DNA repair, and xenobiotic metabolizing genes may influence the age at cancer diagnosis in a homogenous LS cohort with a South African founder germline PV c.1528C>T in the MLH1 gene.

'I Live With Lynch. Cancer Worry Ebbs Into the Background, Then Something Brings It to the Fore.' A Qualitative Interview Study Exploring How Lynch Syndrome Carriers Make Sense of Their Cancer Risks and Implications to Support Decision Making.

Lynch syndrome carriers ('carriers') are presented with complex, emotionally laden choices regarding management of increased genetic cancer risks. Decision aids encourage active involvement in values-based health decisions. This paper aimed to address the research question: How do Lynch syndrome carriers make sense of their chances of developing cancer, and what are the implications for providing support with decision making about genetic cancer risk management? Adult carriers were recruited through a genetics service or involvement with Lynch Syndrome UK. Semi-structured interviews explored lived experiences of carriers' access to care with a focus on decision support. Themes were constructed using framework analysis. These were developed into a conceptual model with recommendations for codevelopment of improved information and support including a tailored decision aid to complement integrated healthcare. Twenty participants included 12 women and eight men, half with a history of cancer. Six overarching themes were: (1) finding balance with Lynch; (2) living 'on higher alert'; (3) managing uncertainty: 'I've thought about it a lot'; (4) burden of responsibility: 'It's on me'; (5) access to joined-up care and support: 'There's something missing'; and (6) influence/pressure from others. This qualitative interview study provided in-depth insights from Lynch syndrome carriers about their lived experiences, informed by their values. Recommendations to empower carriers to make sense of genetic cancer risks and support decisions included accessible, trusted information, educated healthcare professionals, shared decision making, and joined-up integrated care pathways complemented by tailored decision aids.

Immunoprevention Strategies for Colorectal Cancer in Lynch Syndrome Carriers.

The immune revolution that swept the field of oncology in the mid-2010s with the advent of checkpoint inhibitors has led to a paradigm shift in approaches toward adapting new cancer prevention modalities. Cancer vaccines have emerged from this era with astounding potential as a durable intervention to prevent cancers especially for patients with hereditary susceptibilities such as Lynch syndrome carriers. This review covers new insights in the immunoprevention landscape for patients living with Lynch syndrome including highlights ranging from clinical trials exploring the use of chemoprevention agents to boost immune cellularity to investigative studies using novel vaccine approaches to induce long-term antitumor immunity.

Risk of Gastric and Small Intestinal Cancer in Patients With Lynch Syndrome: Data From a Large, Community-Based US Population.

Risk of gastric and small intestinal cancer in Lynch syndrome (LS) remains poorly understood. We investigated the risk of gastric and small intestinal cancer in patients with LS in a large, community-based population. This retrospective cohort study included all patients diagnosed with LS between January 1, 1997, and December 31, 2020, at Kaiser Permanente Northern California. Cumulative incidence of gastric cancer and small intestinal cancer was calculated using competing risk methodology. Among 1,106 patients with LS with a median follow-up of 19.3 years (interquartile range [IQR] 9.4-24.0 years), 11 developed gastric cancer (8 MSH2 , 2 MLH1 and 1 PMS2 ) with a median diagnosis age of 56 years (IQR 42-63 years) and 11 developed small intestinal cancer (6 MSH2 , 3 MLH1 , 1 MSH6 and 1 PMS2 ) with a median diagnosis age of 57 years (IQR 50-66 years). Cumulative incidence by age 80 years was 7.26% (95% confidence internal [CI], 1.80-18.03%) for men and 3.43% (95% CI, 0.50-11.71%) for women for gastric cancer and 7.28% (95% CI, 3.19-13.63%) for men and 2.21% (95% CI, 0.23-9.19%) for women for small intestinal cancer. Pathogenic variant carriers of MSH2 and MLH1 had the highest risk of gastric and small intestinal cancer. History of Helicobacter pylori infection was associated with increased risk of gastric cancer (adjusted odds ratio 5.52; 95% CI, 1.72-17.75). Patients with LS, particularly MSH2 and MLH1 pathogenic variant carriers, had significantly increased lifetime risk of gastric and small intestinal cancer. Testing and treatment of H. pylori infection should be considered for all patients with LS.

Exome Sequencing Identifies Carriers of the Autosomal Dominant Cancer Predisposition Disorders Beyond Current Practice Guideline Recommendations.

The autosomal dominant cancer predisposition disorders hereditary breast and ovarian cancer (HBOC) and Lynch syndrome (LS) are genetic conditions for which early identification and intervention have a positive effect on the individual and public health. The goals of this study were to determine whether germline genetic screening using exome sequencing could be used to efficiently identify carriers of HBOC and LS. Participants were recruited from three geographically and racially diverse sites in the United States (Rochester, MN; Phoenix, AZ; Jacksonville, FL). Participants underwent Exome+ sequencing (Helix Inc, San Mateo, CA) and return of results for specific genetic findings: HBOC (BRCA1 and BRCA1) and LS (MLH1, MSH2, MSH6, PMS2, and EPCAM). Chart review was performed to collect demographics and personal and family cancer history. To date, 44,306 participants have enrolled in Tapestry. Annotation and interpretation of all variants in genes for HBOC and LS resulted in the identification of 550 carriers (prevalence, 1.24%), which included 387 with HBOC (27.2% BRCA1, 42.8% BRCA2) and 163 with LS (12.3% MSH6, 8.8% PMS2, 4.5% MLH1, 3.8% MSH2, and 0.2% EPCAM). More than half of these participants (52.1%) were newly diagnosed carriers with HBOC and LS. In all, 39.2% of HBOC/LS carriers did not satisfy National Comprehensive Cancer Network (NCCN) criteria for genetic evaluation. NCCN criteria were less commonly met in underrepresented minority populations versus self-reported White race (51.5% v 37.5%, P = .028). Our results emphasize the need for wider utilization of germline genetic sequencing for enhanced screening and detection of individuals who have LS and HBOC cancer predisposition syndromes.

Population-Level Identification of Patients With Lynch Syndrome for Clinical Care, Quality Improvement, and Research.

Identification of those at risk of hereditary cancer syndromes using electronic health record (EHR) data sources is important for clinical care, quality improvement, and research. We describe diagnostic processes, previously seldom reported, for a common hereditary cancer syndrome, Lynch syndrome (LS), using EHR data within a community-based, multicenter, demographically diverse health system. Within a retrospective cohort enrolled between 2015 and 2020 at Kaiser Permanente Northern California, we assessed electronic diagnostic domains for LS including (1) family history of LS-associated cancer; (2) personal history of LS-associated cancer; (3) LS screening via mismatch repair deficiency (MMRD) testing of newly diagnosed malignancy; (4) germline genetic test results; and (5) clinician-entered diagnostic codes for LS. We calculated proportions and overlap for each diagnostic domain descriptively. Among 5.8 million individuals, (1) 28,492 (0.49%) had a family history of LS-associated cancer of whom 3,635 (13%) underwent genetic testing; (2) 100,046 (1.7%) had a personal history of a LS-associated cancer; and (3) 8,711 (0.1%) were diagnosed with colorectal cancer of whom 7,533 (86%) underwent MMRD screening and of the positive screens (486), 130 (27%) underwent germline testing. One thousand seven hundred and fifty-seven (0.03%) were diagnosed with endometrial cancer of whom 1,613 (92%) underwent MMRD screening and of the 195 who screened positive, 55 (28%) underwent genetic testing. (4) 30,790 (0.05%) had LS germline genetic testing with 707 (0.01%) testing positive; and (5) 1,273 (0.02%) had a clinician-entered diagnosis of LS. It is feasible to electronically characterize the diagnostic processes of LS. No single data source comprehensively identifies all LS carriers. There is underutilization of LS genetic testing for those eligible and underdiagnosis of LS. Our work informs similar efforts in other settings for hereditary cancer syndromes.

Mitotic abnormalities precede microsatellite instability in lynch syndrome-associated colorectal tumourigenesis

Lynch syndrome (LS) is one of the most common hereditary cancer syndromes worldwide. Dominantly inherited mutation in one of four DNA mismatch repair genes combined with somatic events leads to mismatch repair deficiency and microsatellite instability (MSI) in tumours. Due to a high lifetime risk of cancer, regular surveillance plays a key role in cancer prevention; yet the observation of frequent interval cancers points to insufficient cancer prevention by colonoscopy-based methods alone. This study aimed to identify precancerous functional changes in colonic mucosa that could facilitate the monitoring and prevention of cancer development in LS. The study material comprised colon biopsy specimens (n=71) collected during colonoscopy examinations from LS carriers (tumour-free, or diagnosed with adenoma, or diagnosed with carcinoma) and a control group, which included sporadic cases without LS or neoplasia. The majority (80%) of LS carriers had an inherited genetic MLH1 mutation. The remaining 20% included MSH2 mutation carriers (13%) and MSH6 mutation carriers (7%). The transcriptomes were first analysed with RNA-sequencing and followed up with Gorilla Ontology analysis and Reactome Knowledgebase and Ingenuity Pathway Analyses to detect functional changes that might be associated with the initiation of the neoplastic process in LS individuals. With pathway and gene ontology analyses combined with measurement of mitotic perimeters from colonic mucosa and tumours, we found an increased tendency to chromosomal instability (CIN), already present in macroscopically normal LS mucosa. Our results suggest that CIN is an earlier aberration than MSI and may be the initial cancer driving aberration, whereas MSI accelerates tumour formation. Furthermore, our results suggest that MLH1 deficiency plays a significant role in the development of CIN. The results validate our previous findings from mice and highlight early mitotic abnormalities as an important contributor and precancerous marker of colorectal tumourigenesis in LS. This work was supported by grants from the Jane and Aatos Erkko Foundation, the Academy of Finland (330606 and 331284), Cancer Foundation Finland sr, and the Sigrid Jusélius Foundation. Open access is funded by Helsinki University Library.

Abstract 4096: Comparative molecular profiling of sporadic and Lynch syndrome MSI tumors: Unraveling insights for vaccine design

Abstract Lynch Syndrome (LS) is a hereditary syndrome that predisposes carriers to colorectal cancer (CRC). The hallmark of LS is microsatellite instability (MSI), resulting from a defective DNA mismatch repair (MMR) system. MSI cases have hyper-elevated frameshift mutation rates including “shared” hotspot mutations recurrently across patients. Frameshift mutations can generate neopeptides that activate the immune system. These open the door for preventive vaccines. However, preventive vaccines work best with neopeptides that happen early during tumorigenesis. Here we present 83 newly sequenced adenomas and carcinomas from Lynch syndrome carriers and combine them with previously published 68 Lynch cases and 133 Sporadic cases, thus generating the largest currently available colorectal neoplasia MSI cohort. We leveraged this large cohort to analyze the molecular landscape of adenomas vs carcinoma tumors and Lynch vs sporadic tumors. Employing our recently developed MSIDetect tool on our WGS samples, we identified microsatellite instability in 75% of adenomas, which is higher than previously reported. We found that about 30% of normal adjacent tissues showed MSI, suggesting early mismatch repair defects. This early MSI occurrence supports the potential effectiveness of preventive vaccines. We observed comparable levels of SNVs, microsatellite Indels, and single base signature activity among Lynch adenomas and carcinomas, as well as sporadic carcinomas while adjusting for variations in coverage across different datasets. Moreover, using RNA sequencing data and PCA analysis we found that adenoma and carcinoma cluster together. This large cohort enabled us to identify (as fast as we know for the first time) MS-indels that tend to have a second MS-indel in the same locus. The high similarities observed between Lynch and sporadic tumors allow for their combination in one vaccine. Using the combined MSI cohort we generated a set of about 300 neopeptides that emerged from frequent mutations (&amp;gt;5% in our cohort) with a strong binding affinity for at least one HLA type. We evaluated that a set of about 60 neopeptides per person from that list is predicted likely to initiate an immune response in ~99.5% of the carriers. These findings hold promise for the development of a preventive vaccine capable of targeting early tumorigenic stages. This work is approved under Weill Cornell IRB exemption 1810019672. Citation Format: Hagay Ladany, Mark Grossman, Julian Hess, Nicole Lu, Derin Keskin, Catherine J. Wu, Nir Hacohen, Richard Gallon, John Burn, Heather Hampel, Zsofia Stadler, Gad Getz, Yosef E. Maruvka, Steven Lipkin. Comparative molecular profiling of sporadic and Lynch syndrome MSI tumors: Unraveling insights for vaccine design [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4096.

Abstract 7552: Inhibition of histone methyltransferase EZH2 for immune-interception of colorectal cancer in Lynch syndrome

Abstract Introduction: Colorectal pre-cancers in Lynch Syndrome (LS) display a distinct immune profile thus presenting a unique opportunity to develop novel immune-interception approaches to halt carcinogenesis. Epigenetic modulation by EZH2 of immune-related genes has been implicated in many cancers including colorectal but it has yet to be explored in LS carcinogenesis. The main objective of this study is to test the effect of EZH2 inhibition on immune cell profiling, colorectal carcinogenesis, gene expression, and histone methylation, using ex vivo organoids and a LS mouse model. Methods: A mouse model of LS colorectal carcinogenesis (Villin-Cre;Msh2fl/fl;TgfβRII-KI; herein referred to as VCMsh2THu) and ex vivo colonic organoids were utilized to assess the effects of the EZH2 inhibitor GSK503. Mice were treated for 9-weeks with GSK503 with downstream studies exploring polyp multiplicity, changes to the immune landscape, and epigenetic analyses to derive mechanistic insights into EZH2 regulation in LS. Results: GSK503 significantly altered transcriptomic changes in VCMsh2THu organoids with tissue-specific tropism for dysplastic organoids as compared to organoids prepared from adjacent normal mucosa. GSK503 significantly increased CD4+and CD8+ T cells in splenocytes and colonic mucosa of treated mice compared to controls in vitro and in vivo. A preventive-dose (200μg/kg) of GSK503 for 9 weeks significantly reduced adenoma multiplicity in the large intestine of VCMsh2THu mice with significant changes in the immune landscape of treated mice compared to controls. The data suggests GSK503 significantly enriched both total and activated cytotoxic T-lymphocytes CD8+/CD137+), stromal macrophages (CD68+), and activated helper T-lymphocytes (CD4+/CD134+) in the large intestine of VCMsh2THu mice. Transcriptome and molecular analyses using IHC, Western blots, and computational tools showed activation of immune and apoptotic markers with concomitant reduction of H3K27 methylation levels in colonic crypts. ChIPseq analyses revealed decreased levels of H3K27me3 and H3K4me1 (enhancer), a slight increased levels of H3K27ac (enhancer) marks with no changes in levels of H3K4me3 in treated mice, indicating that EZH2 inhibition yields global reprograming of poised promoters and active enhancers in the LS mouse genome. Conclusions: Collectively, our findings reveal that GSK503 has a promising potential as an immuno-interception modality establishing the framework for launching phase I clinical trials with EZH2 inhibitors for LS carriers. Citation Format: Fahriye Duzagac, Charles M. Bowen, Laura Reyes-Uribe, Mahira Zaheer, Jacklyn Thompson, Nan Deng, Melissa Taggart, Abhinav Jain, Winfried Edelmann, Krishna M. Sinha, Eduardo Vilar. Inhibition of histone methyltransferase EZH2 for immune-interception of colorectal cancer in Lynch syndrome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7552.

The comprehensive English National Lynch Syndrome Registry: development and description of a new genomics data resource

Lynch Syndrome (LS) is a cancer predisposition syndrome caused by constitutional pathogenic variants in the mismatch repair (MMR) genes. To date, fragmentation of clinical and genomic data has restricted understanding of national LS ascertainment and outcomes, and precluded evaluation of NICE guidance on testing and management. To address this, via collaboration between researchers, the National Disease Registration Service (NDRS), NHS Genomic Medicine Service Alliances (GMSAs), and NHS Regional Clinical Genetics Services, a comprehensive registry of LS carriers in England has been established. For comprehensive ascertainment of retrospectively identified MMR pathogenic variant (PV) carriers (diagnosed prior to January 1, 2023), information was retrieved from all clinical genetics services across England, then restructured, amalgamated, and validated via a team of trained experts in NDRS. An online submission portal was established for prospective ascertainment from January 1, 2023. The resulting data, stored in a secure database in NDRS, were used to investigate the demographic and genetic characteristics of the cohort, censored at July 25, 2023. Cancer outcomes were investigated via linkage to the National Cancer Registration Dataset (NCRD). A total of 11,722 retrospective and 570 prospective data submissions were received, resulting in a comprehensive English National Lynch Syndrome Registry (ENLSR) comprising 9030 unique individuals. The most frequently identified pathogenic MMR genes were MSH2 and MLH1 at 37.2% (n=3362) and 29.1% (n=2624), respectively. 35.9% (n=3239) of the ENLSR cohort received their LS diagnosis before their first cancer diagnosis (presumptive predictive germline test). Of these, 6.3% (n=204) developed colorectal cancer, at a median age of initial diagnosis of 51 (IQR 40-62), compared to 73 years (IQR 64-80) in the general population (p<0.0001). The ENLSR represents the first comprehensive national registry of PV carriers in England and one of the largest cohorts of MMR PV carriers worldwide. The establishment of a secure, centralised infrastructure and mechanism for routine registration of newly identified carriers ensures sustainability of the data resource. This work was funded by the Wellcome Trust, Cancer Research UK and Bowel Cancer UK. The funder of this study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.

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.

Metachronous colorectal cancer risk according to Lynch syndrome pathogenic variant after extensive versus partial colectomy in the Netherlands: a retrospective cohort study

Extensive colectomy (subtotal or total colectomy) is often advised for carriers of Lynch syndrome with colorectal cancer. However, the risk of metachronous colorectal cancer might differ by Lynch syndrome variant, meaning that partial colectomy, which has better functional outcomes, might be adequate for some patients with low-risk variants. We aimed to assess the risk of metachronous colorectal cancer after partial colectomy and extensive colectomy in carriers of Lynch syndrome with different pathogenic variants. For this retrospective cohort study, carriers of Lynch syndrome with colorectal cancer in the Netherlands were identified by linkage of the Dutch Foundation for the Detection of Hereditary Tumors (StOET) database and the Dutch Nationwide Network and Registry of Histopathology and Cytopathology (PALGA) database. Data on demographics, Lynch syndrome variants, colorectal cancers, surgery types, mortality, and surveillance colonoscopies were extracted. Data on colorectal cancer and surveillance colonoscopies were updated until Feb 28, 2022. Data on survival status was updated until Feb 7, 2022. MLH1, MSH2, and EPCAM were classified as high-risk variants and MSH6 and PMS2 as low-risk variants. Patients for whom the type of surgery was unknown were excluded. Cox regression time-to-event analyses were done to assess the risk of metachronous colorectal cancer in four subgroups based on pathogenic variant (high-risk vs low-risk variants) and the extent of surgery (extensive colectomy vs partial colectomy). Sex, age at the time of primary colorectal cancer, primary colorectal cancer stage, performance of surveillance colonoscopies, adherence to the surveillance guidelines, and time period of primary colorectal cancer diagnosis were added to the model as possible confounders. Metachronous colorectal cancer was defined as colorectal cancer diagnosed more than 6 months after the primary colorectal cancer. Patients were censored at time of death or assembly of the database. Of 1908 carriers of Lynch syndrome registered in StOET, 532 with a history of colorectal cancer were identified after linkage with PALGA. Five carriers were excluded because of an unknown surgery type, leaving 527 in our sample (mean age at primary colorectal cancer 48·7 years [SD 12·1]; 274 [52%] male and 253 [48%] female). 121 (23%) patients developed metachronous colorectal cancer (median time from primary colorectal cancer to metachronous colorectal cancer 11·0 years [IQR 2·1-17·8]). Metachronous colorectal cancer occurred in 12 (12%) of 97 patients with high-risk variants and extensive colectomy, in 85 (32%) of 267 patients with high-risk variants and partial colectomy, in zero (0%) of 11 patients with low-risk variants and extensive colectomy, and in 24 (16%) of 152 patients with low-risk variants and partial colectomy. Partial colectomy was associated with a higher risk of metachronous colorectal cancer than extensive colectomy in the high-risk variant group (hazard ratio 1·97, 95% CI 1·04-3·73; p=0·039). The risk of metachronous colorectal cancer did not differ between carriers of low-risk variants who had partial colectomy and those of high-risk variants who had extensive colectomy (1·14, 0·55-2·36; p=0·72). The risk of metachronous colorectal cancer after partial colectomy in carriers of low-risk variants is similar to the risk after extensive colectomy in carriers of high-risk variants. This finding suggests that partial colectomy followed by endoscopic surveillance is an appropriate management approach to treat colorectal cancer in carriers of low-risk Lynch syndrome variants. None.

Serum matrix metalloproteinase-7: a potential biomarker in patients with Lynch Syndrome.

The expression of tissue and serum matrix metalloproteinase-7 (MMP-7) was shown to be elevated both in colon cancer and dysplastic lesions. We aimed to evaluate, for the first time, its role as a diagnostic marker in Lynch syndrome (LS) carriers, a hereditary syndrome with predisposition to colon cancer. This was a case control study. Baseline serum MMP-7 levels were determined by ELISA in 40 colon cancer patients, 62 LS-carriers and 60 healthy controls. Retrieved data from medical files included demographics, background diseases, clinical data regarding tumor characteristics and genetic data. We assessed the association of serum MMP-7 levels with different variables in the study cohort using linear regression model adjusted for potential confounders. In crude analysis, serum MMP-7 levels were significantly higher in colon cancer group compared to LS-carriers and controls [median (IQR) 4.1 ng/ml (2.7-6.0), 2.3 ng/ml (1.7-3.1), 2.5 ng/ml (1.5-3.7), respectively; p value - p < 0.001) while there was no difference between the two last groups (p value = 0.583). However, after adjusting for age and gender, LS-carriers' patients had 18% higher concentrations of serum MMP-7 compared to healthy controls (p value = 0.037), while colon cancer patients had 50% higher serum MMP-7 level in comparison to healthy controls (p value < 0.001). Additionally, age was positively associated with higher serum MMP-7 levels across all study groups (r = 0.67, p value < 0.001). In contrast, no correlation was observed between serum MMP-7 and either tumor staging and gene mutation. Age-adjusted serum MMP-7 levels in asymptomatic LS carriers are higher than its levels in healthy population. While in colon cancer, MMP-7 higher level probably reflects the tumor burden and may have a prognostic effect, its significance and clinical applicability as a biomarker for tumorigenesis in LS is less clear and should be elucidated.

Abstract 5768: Genetic screening in a tertiary medical center identifies carriers of cancer predisposition diseases that would be missed by clinical guidelines

Abstract Two inherited autosomal dominant cancer predisposition conditions - BRCA related hereditary breast and ovarian cancer (HBOC) and Lynch syndrome (LS) - are termed Centers for Disease Control and Prevention Tier 1 (CDCT1) genetic conditions, for which early identification and intervention have a positive impact on public health. Selection of individuals for genetic testing for these conditions is based on personal and family history. The goal of this study was to evaluate whether screening in a tertiary medical center using exome sequencing could efficiently identify carriers of HBOC and LS and to determine the frequency of incremental carriers identified outside of traditional clinical practice guidelines. Participants from three geographically diverse Mayo Clinic practices in the USA (Rochester MN, Phoenix AZ, Jacksonville FL) consented to clinical “Exome+” sequencing (Helix, San Mateo, CA; Mayo GeneGuide, Rochester, MN) in the TAPESTRY study (NCT05212428), which links sequencing data with electronic health records and the return of CDCT1 genetic findings. For this study we focused on two inherited cancer predisposition conditions: BRCA-related HBOC (BRCA1 and BRCA2) and LS (MLH1, MSH2, MSH6, PMS2 and EPCAM). Detailed chart review to collect demographic information, personal and family history, and assessment of clinical practice guidelines for genetic evaluation (National Cancer Control Network 2021). To date, 44,306 patients have enrolled and sequenced in TAPESTRY. Annotation and interpretation of all variants in 7 genes for HBOC and LS resulted in identification of 550 carriers (prevalence 1.24%) which included 387 with HBOC (27.2% BRCA1, 42.8% BRCA2) and 163 with LS (12.3% MSH6, 8.8% PMS2, 4.5% MLH1, 3.8% MSH2 and 0.2% EPCAM). Demographics of the cohort included: 62.7% female, mean age 55.2 years, non-white race 9.6% and 3.8% Hispanic/Latino ethnicity. A personal history of cancer was present in 46.4% of test positive patients, including 22.5% of HBOC patients with breast or ovarian cancer and 20.9% of LS patients with colorectal or uterine cancer. More than half of the patients (52.1%) were newly diagnosed with HBOC and LS based on the results of this study. Overall, 39.2% of HBOC/LS carriers identified through Exome+ sequencing did not satisfy NCCN criteria for genetic evaluation, this was higher for LS (56.2%) compared to HBOC (32%). Amongst those newly diagnosed with HBOC/LS (n=286), NCCN criteria were not satisfied in 60% of cases (78% for LS and 51% for HBOC). Of the pathogenic germline variant carriers who met NCCN guidelines for testing, 34.2% were not aware of their diagnosis prior to participation in this study. Our results emphasize the need for wide genomic screening for CDCT1 cancer predisposition syndromes. Such screening could identify at-risk carriers of HBOC and LS, who would not otherwise be identified through clinical practice guidelines. Citation Format: Emily Gay, Niloy Jewel Samadder, Michelle L. Bublitz, Melanie M. Peterson, Tammy A. Wilson, Lorelei A. Bandel, Sebastian M. Armasu, Robert A. Vierkant, Matthew J. Ferber, Eric W. Klee, Nicholas B. Larson, Teresa M. Kruisselbrink, Timothy B. Curry, Jan B. Egan, Jennifer L. Kemppainen, Jessa S. Bidwell, Jennifer L. Anderson, Tammy M. McAllister, T'Nita S. Walker, Katie L. Kunze, Vanda Lindpere, Michael A. Golafshar, Margaret Klint, Richard J. Presutti, William V. Bobo, Aleksander Sekulic, Jolene M. Summer Bolster, Cheryl L. Willman, Konstantinos N. Lazaridis. Genetic screening in a tertiary medical center identifies carriers of cancer predisposition diseases that would be missed by clinical guidelines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5768.

Colorectal surveillance outcomes from an institutional longitudinal cohort of lynch syndrome carriers.

Lynch Syndrome (LS) carriers have a significantly increased risk of developing colorectal cancer (CRC) during their lifetimes. Further stratification of this patient population may help in identifying additional risk factors that predispose to colorectal carcinogenesis. In most LS patients CRC may arise from adenomas, although an alternative non-polypoid carcinogenesis pathway has been proposed for PMS2 carriers. Using data from our institutional LS cohort, our aim was to describe our current colorectal screening outcomes with a focus on the incidence of adenomas in the context of different MMR genotypes and patient demographics such as gender, race, and ethnicity. We collected demographics, genetic, colonoscopy, and pathology results from a total of 163 LS carriers who obtained regular screening care at MD Anderson Cancer Center. Data were extracted from the electronic health records into a REDCap database for analysis. Logistic regressions were performed to measure the association between MMR variants and the likelihood of adenomas, advanced adenomas, and CRC. Then, we analyzed the cumulative incidences of these outcomes for the first 36 months following enrollment using Kaplan-Meier incidence curves, and Cox proportional hazard regressions. On multivariate analysis, age (≥45 years old) was associated with an increased risk of developing adenomas (P=0.034). Patients with a prior or active cancer status were less likely to develop adenomas (P=0.015), despite of the lack of association between surgical history with this outcome (P=0.868). We found no statistically significant difference in likelihood of adenoma development between MLH1 and MSH2/EPCAM, MSH6, and PMS2 carriers. Moreover, we observed no statistically significant difference in the likelihood of advanced adenomas or CRC for any measured covariates. On Cox proportional hazard, compared to MLH1 carriers, the incidence of adenomas was highest among MSH2/EPCAM carriers during for the first 36-months of follow-up (P<0.001). We observed a non-statistically significant trend for Hispanics having a higher and earlier cumulative incidence of adenomas compared to non-Hispanics (P=0.073). No MMR carrier was more likely to develop advanced adenomas. No difference in the incidence of CRC by MMR gene (P=0.198). Screening recommendations for CRC in LS patients should be based on specific MMR variants and should also be tailored to consider patient demographics.

Evaluating colonoscopy screening intervals in patients with Lynch syndrome from a large Canadian registry.

Lynch syndrome (LS) screening guidelines originally recommended colonoscopy every 1 to 2 years, beginning between the ages of 20 and 25 years. Recent studies have questioned the benefits of these short screening intervals in preventing colorectal cancer (CRC). Our goal is to determine how colonoscopy screening intervals impact CRC in patients with LS. We analyzed the demographics, screening practices, and outcomes of patients with LS identified through the clinic based Familial Gastrointestinal Cancer Registry at the Zane Cohen Centre, Sinai Health System, Toronto, Canada. A total of 429 patients with LS were identified with median follow-up of 9.2 years; 44 developed CRC. We found a positive trend between shorter screening intervals and the number of adenomas detected during colonoscopy. Any new adenoma detected at screening decreased 10-year CRC incidence by 11.3%. For MLH1 carriers, a screening interval of 1-2 years vs 2-3 years led to a 20-year cumulative CRC risk reduction of 28% and 14% in females and males, respectively. For MSH2 carriers, this risk reduction was 29% and 17%, respectively, and for male MSH6 carriers 18%. Individuals without any adenomas detected (53.4% of LS carriers) had an increased 20-year CRC risk of 25.7% and 57.2% for women and men, respectively, compared with those diagnosed with adenomas at screening. The recommended colonoscopy screening interval of 1-2 years is efficient at detecting adenomas and reducing CRC risk. The observation that 53.4% of LS patients never had an adenoma warrants further investigation about a possible adenoma-free pathway.

Lynch syndrome cancer vaccines: A roadmap for the development of precision immunoprevention strategies.

Hereditary cancer syndromes (HCS) account for 5~10% of all cancer diagnosis. Lynch syndrome (LS) is one of the most common HCS, caused by germline mutations in the DNA mismatch repair (MMR) genes. Even with prospective cancer surveillance, LS is associated with up to 50% lifetime risk of colorectal, endometrial, and other cancers. While significant progress has been made in the timely identification of germline pathogenic variant carriers and monitoring and early detection of precancerous lesions, cancer-risk reduction strategies are still centered around endoscopic or surgical removal of neoplastic lesions and susceptible organs. Safe and effective cancer prevention strategies are critically needed to improve the life quality and longevity of LS and other HCS carriers. The era of precision oncology driven by recent technological advances in tumor molecular profiling and a better understanding of genetic risk factors has transformed cancer prevention approaches for at-risk individuals, including LS carriers. MMR deficiency leads to the accumulation of insertion and deletion mutations in microsatellites (MS), which are particularly prone to DNA polymerase slippage during DNA replication. Mutations in coding MS give rise to frameshift peptides (FSP) that are recognized by the immune system as neoantigens. Due to clonal evolution, LS tumors share a set of recurrent and predictable FSP neoantigens in the same and in different LS patients. Cancer vaccines composed of commonly recurring FSP neoantigens selected through prediction algorithms have been clinically evaluated in LS carriers and proven safe and immunogenic. Preclinically analogous FSP vaccines have been shown to elicit FSP-directed immune responses and exert tumor-preventive efficacy in murine models of LS. While the immunopreventive efficacy of "off-the-shelf" vaccines consisting of commonly recurring FSP antigens is currently investigated in LS clinical trials, the feasibility and utility of personalized FSP vaccines with individual HLA-restricted epitopes are being explored for more precise targeting. Here, we discuss recent advances in precision cancer immunoprevention approaches, emerging enabling technologies, research gaps, and implementation barriers toward clinical translation of risk-tailored prevention strategies for LS carriers. We will also discuss the feasibility and practicality of next-generation cancer vaccines that are based on personalized immunogenic epitopes for precision cancer immunoprevention.

Highly Sensitive Microsatellite Instability and Immunohistochemistry Assessment in Endometrial Aspirates as a Tool for Cancer Risk Individualization in Lynch Syndrome

Women with Lynch syndrome (LS) are at increased risk of endometrial cancer (EC), among other tumors, and are characterized by mismatch repair (MMR) deficiency and microsatellite instability (MSI). While risk-reducing gynecologic surgeries effectively decrease EC incidence, doubts arise regarding the appropriate timing of the surgery. We explored the usefulness of highly sensitive MSI (hs-MSI) assessment in endometrial aspirates for individualizing gynecologic surveillance in LS carriers. Ninety-three women with LS, 25 sporadic EC patients (9 MMR-proficient and 16 MMR-deficient), and 30 women with benign gynecologic disease were included in this study. hs-MSI was assessed in prospectively collected endometrial aspirates in 67 LS carriers, EC cases, and controls. MMR, PTEN, ARID1A, and PAX2 protein expression patterns were evaluated in the LS samples. Follow-up aspirates from 8 LS carriers were also analyzed. Elevated hs-MSI scores were detected in all aspirates from MMR-deficient EC cases (3 LS and 16 sporadic) and negative in aspirates from controls and MMR-proficient EC cases. Positive hs-MSI scores were also detected in all 4 LS aspirates reported as complex hyperplasia. High hs-MSI was also present in 10 of 49 aspirates (20%) from LS carriers presenting a morphologically normal endometrium, where MMR protein expression loss was detected in 69% of the samples. Interestingly, the hs-MSI score was positively correlated with MMR-deficient gland density and the presence of MMR-deficient clusters, colocalizing PTEN and ARID1A expression loss. High hs-MSI scores and clonality were evidenced in 2 samples collected up to 4 months before EC diagnosis; hs-MSI scores increased over time in 5 LS carriers, whereas they decreased in a patient with endometrial hyperplasia after progestin therapy. In LS carriers, elevated hs-MSI scores were detected in aspirates from premalignant and malignant lesions and normal endometrium, correlating with MMR protein loss. hs-MSI assessment and MMR immunohistochemistry may help individualize EC risk assessment in women with LS.

Metachronous Colorectal Cancer in Icelandic MSH6 and PMS2 Lynch Syndrome Carriers in 1955–2017: A Population-based Study

Metachronous Colorectal Cancer in Icelandic MSH6 and PMS2 Lynch Syndrome Carriers in 1955–2017: A Population-based Study