New-onset diabetes is a predictive risk factor for pancreatic lesions in high-risk individuals: An observational cohort study.

Background and Objectives: Pancreatic cancer (PC) is the third cause of cancer-related deaths. Early detection and interception of premalignant pancreatic lesions represent a promising strategy to improve outcomes. We evaluated risk factors of focal pancreatic lesions (FPLs) in asymptomatic individuals at hereditary high risk for PC. Methods: This is an observational single-institution cohort study conducted over a period of 5 years. Surveillance was performed through imaging studies (EUS or magnetic resonance imaging/magnetic resonance cholangiopancreatography) and serum biomarkers. We collected demographic characteristics and used univariate and multivariate logistic regression models to evaluate associations between potential risk factors and odd ratios (ORs) for FPL development. Results: A total of 205 patients completed baseline screening. Patients were followed up to 53 months. We detected FPL in 37 patients (18%) at baseline; 2 patients had lesions progression during follow-up period, 1 of them to PC. Furthermore, 13 patients developed new FPLs during the follow-up period. Univariate and multivariate analyses revealed that new-onset diabetes (NOD) is strongly associated with the presence of FPL (OR, 10.94 [95% confidence interval, 3.01-51.79; P < 0.001]; OR, 9.98 [95% confidence interval, 2.15-46.33; P = 0.003]). Follow-up data analysis revealed that NOD is also predictive of lesions progression or development of new lesions during screening (26.7% vs. 2.6%; P = 0.005). Conclusions: In a PC high-risk cohort, NOD is significantly associated with presence of FPL at baseline and predictive of lesions progression or new lesions during surveillance.

MONET: a database for prediction of neoantigens derived from microsatellite loci.

Background: Microsatellite instability (MSI) secondary to mismatch repair (MMR) deficiency is characterized by insertions and deletions (indels) in short DNA sequences across the genome. These indels can generate neoantigens, which are ideal targets for precision immune interception. However, current neoantigen databases lack information on neoantigens arising from coding microsatellites. To address this gap, we introduce The MicrOsatellite Neoantigen Discovery Tool (MONET). Method: MONET identifies potential mutated tumor-specific neoantigens (neoAgs) by predicting frameshift mutations in coding microsatellite sequences of the human genome. Then MONET annotates these neoAgs with key features such as binding affinity, stability, expression, frequency, and potential pathogenicity using established algorithms, tools, and public databases. A user-friendly web interface (https://monet.mdanderson.org/) facilitates access to these predictions. Results: MONET predicts over 4 million and 15 million Class I and Class II potential frameshift neoAgs, respectively. Compared to existing databases, MONET demonstrates superior coverage (>85% vs. <25%) using a set of experimentally validated neoAgs. Conclusion: MONET is a freely available, user-friendly web tool that leverages publicly available resources to identify neoAgs derived from microsatellite loci. This systems biology approach empowers researchers in the field of precision immune interception.

Novel Cancer Prevention Strategies in Individuals With Hereditary Cancer Syndromes: Focus on BRCA1, BRCA2, and Lynch Syndrome.

Germline pathogenic variants (PVs) in the BRCA1 and BRCA2 genes confer elevated risks of breast, ovarian, and other cancers. Lynch syndrome (LS) is associated with increased risks of multiple cancer types including colorectal and uterine cancers. Current cancer risk mitigation strategies have focused on pharmacologic risk reduction, enhanced surveillance, and preventive surgeries. While these approaches can be effective, they stand to be improved on because of either limited efficacy or undesirable impact on quality of life. The current review summarizes ongoing investigational efforts in cancer risk prevention strategies for patients with germline PVs in BRCA1, BRCA2, or LS-associated genes. These efforts span radiation, surgery, and pharmacology including vaccine strategies. Understanding the molecular events involved in the premalignant to malignant transformation in high-risk individuals may ultimately contribute significantly to novel prevention strategies.

Current Trends in Vaccine Development for Hereditary Colorectal Cancer Syndromes.

The coming of age for cancer treatment has experienced exponential growth in the last decade with the addition of immunotherapy as the fourth pillar to the fundamentals of cancer treatment-chemotherapy, surgery, and radiation-taking oncology to an astounding new frontier. In this time, rapid developments in computational biology coupled with immunology have led to the exploration of priming the host immune system through vaccination to prevent and treat certain subsets of cancer such as melanoma and hereditary colorectal cancer. By targeting the immune system through tumor-specific antigens-namely, neoantigens (neoAgs)-the future of cancer prevention may lie within arm's reach by employing neoAg vaccines as an immune-preventive modality for hereditary cancer syndromes like Lynch syndrome. In this review, we discuss the history, current trends, utilization, and future direction of neoAg-based vaccines in the setting of hereditary colorectal cancer.

PIGA Mutations and Glycosylphosphatidylinositol Anchor Dysregulation in Polyposis-Associated Duodenal Tumorigenesis.

The pathogenesis of duodenal tumors in the inherited tumor syndromes familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP) is poorly understood. This study aimed to identify genes that are significantly mutated in these tumors and to explore the effects of these mutations. Whole exome and whole transcriptome sequencing identified recurrent somatic coding variants of phosphatidylinositol N-acetylglucosaminyltransferase subunit A (PIGA) in 19/70 (27%) FAP and MAP duodenal adenomas, and further confirmed the established driver roles for APC and KRAS. PIGA catalyzes the first step in glycosylphosphatidylinositol (GPI) anchor biosynthesis. Flow cytometry of PIGA-mutant adenoma-derived and CRISPR-edited duodenal organoids confirmed loss of GPI anchors in duodenal epithelial cells and transcriptional profiling of duodenal adenomas revealed transcriptional signatures associated with loss of PIGA. IMPLICATIONS: PIGA somatic mutation in duodenal tumors from patients with FAP and MAP and loss of membrane GPI-anchors may present new opportunities for understanding and intervention in duodenal tumorigenesis.

Genomic Landscape of Lynch Syndrome Colorectal Neoplasia Identifies Shared Mutated Neoantigens for Immunoprevention.

BACKGROUND & AIMS: Lynch syndrome (LS) carriers develop mismatch repair-deficient neoplasia with high neoantigen (neoAg) rates. No detailed information on targetable neoAgs from LS precancers exists, which is crucial for vaccine development and immune-interception strategies. We report a focused somatic mutation and frameshift-neoAg landscape of microsatellite loci from colorectal polyps without malignant potential (PWOMP), precancers, and early-stage cancers in LS carriers. METHODS: We generated paired whole-exome and transcriptomic sequencing data from 8 colorectal PWOMP, 41 precancers, 8 advanced precancers, and 12 early-stage cancers of 43 LS carriers. A computational pipeline was developed to predict, rank, and prioritize the top 100 detected mutated neoAgs that were validated in vitro using ELISpot and tetramer assays. RESULTS: Mutation calling revealed >10 mut/Mb in 83% of cancers, 63% of advanced precancers, and 20% of precancers. Cancers displayed an average of 616 MHC-I neoAgs/sample, 294 in advanced precancers, and 107 in precancers. No neoAgs were detected in PWOMP. A total of 65% of our top 100 predicted neoAgs were immunogenic in vitro, and were present in 92% of cancers, 50% of advanced precancers, and 29% of precancers. We observed increased levels of naïve CD8+ and memory CD4+ T cells in mismatch repair-deficient cancers and precancers via transcriptomics analysis. CONCLUSIONS: Shared frameshift-neoAgs are generated within unstable microsatellite loci at initial stages of LS carcinogenesis and can induce T-cell responses, generating opportunities for vaccine development, targeting LS precancers and early-stage cancers.

Sustained Disease Control in Immune Checkpoint Blockade Responders with Microsatellite Instability-high Colorectal Cancer after Treatment Termination.

Immune checkpoint inhibitors improve survival in patients with mismatch repair deficiency/microsatellite instability-high (MSI-H) colorectal cancer. The recurrence outcomes following discontinuation of immunotherapy after prolonged disease control have not been definitively reported in large series. Records from patients with advanced MSI-H colorectal cancer from The University of Texas - MD Anderson Cancer Center who received immunotherapy between 2014 and 2022 and stopped after prolonged clinical benefit were reviewed. Median progression-free and overall survival were estimated. Associations between the event of recurrence and coexisting mutations (KRAS/NRAS, BRAFV600E), metastatic organ involvement (lung, liver, lymph node, or peritoneum), metastatic timing (synchronous vs. metachronous), prior immunotherapy [anti-PD-(L)1 alone or in combination with anti-CTLA antibodies], etiology of MSI status (sporadic vs. hereditary non-polyposis colorectal cancer), and duration of immunotherapy were assessed. Sixty-four patients with MSI-H colorectal cancer without progression on immunotherapy were reviewed. Of these 48 and 16 received anti-PD(L)1 antibody alone or in combination with anti-CTLA-4 antibody, respectively. Median exposure to immunotherapy was 17.6 months (range, 1.3-51.9). After a median follow-up of 22.6 months (range, 0.3-71.7) after stopping immunotherapy, 56 of 64 patients (88%) remained without disease progression. Lung metastases were associated with recurrence/progression (OR, 6.1; P = 0.04), but coexisting mutation, primary tumor sidedness, and immunotherapy were not. These data provide a retrospective, single-institution analysis that showed that most patients with advanced MSI-H colorectal cancer do not recur after treatment cessation, regardless of the reason for stopping treatment or a variety of patient and disease features, supporting an optimistic prognosis of sustained disease control. SIGNIFICANCE: Outcomes for patients with MSI-H colorectal cancer stopping immunotherapy after disease control remain unknown. Sixty-four patients with MSI-H colorectal cancer from our institution stopping treatment for sustained benefit or toxicity were retrospectively assessed. After median follow up of 22 months and median immunotherapy exposure of 18 months, 88% patients remained without progression. All patients who recurred or progressed and were rechallenged with immunotherapy have continued to experience disease control.

Human intestinal organoids from Cronkhite-Canada syndrome patients reveal link between serotonin and proliferation.

Cronkhite-Canada Syndrome (CCS) is a rare, noninherited polyposis syndrome affecting 1 in every million individuals. Despite over 50 years of CCS cases, the etiopathogenesis and optimal treatment for CCS remains unknown due to the rarity of the disease and lack of model systems. To better understand the etiology of CCS, we generated human intestinal organoids (HIOs) from intestinal stem cells isolated from 2 patients. We discovered that CCS HIOs are highly proliferative and have increased numbers of enteroendocrine cells producing serotonin (also known as 5-hydroxytryptamine or 5HT). These features were also confirmed in patient tissue biopsies. Recombinant 5HT increased proliferation of non-CCS donor HIOs and inhibition of 5HT production in the CCS HIOs resulted in decreased proliferation, suggesting a link between local epithelial 5HT production and control of epithelial stem cell proliferation. This link was confirmed in genetically engineered HIOs with an increased number of enteroendocrine cells. This work provides a new mechanism to explain the pathogenesis of CCS and illustrates the important contribution of HIO cultures to understanding disease etiology and in the identification of novel therapies. Our work demonstrates the principle of using organoids for personalized medicine and sheds light on how intestinal hormones can play a role in intestinal epithelial proliferation.

Exploring Stakeholders' Perspectives on Implementing Universal Germline Testing for Colorectal Cancer: Findings From a Clinical Practice Survey.

PURPOSE: New guidelines recommend considering germline genetic testing for all patients with colorectal cancer (CRC). However, there is a lack of data on stakeholders' perspectives on the advantages and barriers of implementing universal germline testing (UGT). This study assessed the perspectives of members of the Collaborative Group of the Americas on Inherited Gastrointestinal Cancer (CGA-IGC) regarding the implementation of UGT for patients with CRC, including readiness, logistics, and barriers. METHODS: A cross-sectional survey was sent to 317 active members of CGA-IGC. The survey included sections on demographics, clinical practice specialty, established institutional practices for testing, and questions pertaining to support of and barriers to implementing UGT for patients with CRC. RESULTS: Eighty CGA-IGC members (25%) participated, including 42 genetic counselors (53%) and 14 gastroenterologists (18%). Forty-seven (59%) reported an academic medical center as their primary work setting, and most participants (56%) had more than 10 years of clinical practice. Although most participants (73%) supported UGT, 54% indicated that changes in practice would be required before adopting UGT, and 39% indicated that these changes would be challenging to implement. There was support for both genetics and nongenetics providers to order genetic testing, and a majority (57%) supported a standardized multigene panel rather than a customized gene panel. Key barriers to UGT implementation included limited genetics knowledge among nongenetics providers, time-consuming processes for obtaining consent, ordering tests, disclosing results, and lack of insurance coverage. CONCLUSION: This study demonstrates wide support among hereditary GI cancer experts for implementation of UGT for patients with CRC. However, alternative service delivery models using nongenetics providers should be considered to address the logistical barriers to UGT implementation, particularly the growing demand for genetic testing.

Exercise Training Reduces the Inflammatory Response and Promotes Intestinal Mucosa-Associated Immunity in Lynch Syndrome.

PURPOSE: Lynch syndrome (LS) is a hereditary condition with a high lifetime risk of colorectal and endometrial cancers. Exercise is a non-pharmacologic intervention to reduce cancer risk, though its impact on patients with LS has not been prospectively studied. Here, we evaluated the impact of a 12-month aerobic exercise cycling intervention in the biology of the immune system in LS carriers. PATIENTS AND METHODS: To address this, we enrolled 21 patients with LS onto a non-randomized, sequential intervention assignation, clinical trial to assess the effect of a 12-month exercise program that included cycling classes 3 times weekly for 45 minutes versus usual care with a one-time exercise counseling session as control. We analyzed the effects of exercise on cardiorespiratory fitness, circulating, and colorectal-tissue biomarkers using metabolomics, gene expression by bulk mRNA sequencing, and spatial transcriptomics by NanoString GeoMx. RESULTS: We observed a significant increase in oxygen consumption (VO2peak) as a primary outcome of the exercise and a decrease in inflammatory markers (prostaglandin E) in colon and blood as the secondary outcomes in the exercise versus usual care group. Gene expression profiling and spatial transcriptomics on available colon biopsies revealed an increase in the colonic mucosa levels of natural killer and CD8+ T cells in the exercise group that were further confirmed by IHC studies. CONCLUSIONS: Together these data have important implications for cancer interception in LS, and document for the first-time biological effects of exercise in the immune system of a target organ in patients at-risk for cancer.

The Cancer Moonshot Immuno-Oncology Translational Network at 5: accelerating cancer immunotherapies.

The Immuno-Oncology Translational Network (IOTN) was established in 2018 as part of the Cancer Moonshot. In 2022, President Joe Biden set new goals to reduce the cancer death rate by half within 25 years and improve the lives of people with cancer and cancer survivors. The IOTN is focused on accelerating translation of cancer immunology research, from bench to bedside, and improving immunotherapy outcomes across a wide array of cancers in the adult population. The unique structure and team science approach of the IOTN is designed to accelerate discovery and evaluation of novel immune-based therapeutic and prevention strategies. In this article, we describe IOTN progress to date, including new initiatives and the development of a robust set of resources to advance cancer immunology research. We summarize new insights by IOTN researchers, some of which are ripe for translation for several types of cancers. Looking to the future, we identify barriers to the translation of immuno-oncology concepts into clinical trials and key areas for action and improvements that are suitable for high-yield investments. Based on these experiences, we recommend novel National Institutes of Health funding mechanisms and development of new resources to address these barriers.

Advances in vaccine development for cancer prevention and treatment in Lynch Syndrome.

Lynch Syndrome (LS) is one of the most common hereditary cancer syndromes, and is caused by mutations in one of the four DNA mismatch repair (MMR) genes, namely MLH1, MSH2, MSH6 and PMS2. 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 the most common. As a result, MMR-deficient (MMRd) cells generate increased rates of tumor-specific neoantigens (neoAgs) that can be recognized by the immune system to activate cancer cell killing. In this context, LS is an ideal disease to leverage immune-interception strategies. Therefore, the identification of these neoAgs is an ongoing effort for the development of LS cancer preventive vaccines. In this review, we summarize the computational methods used for in silico neoAg prediction, including their challenges, and the experimental techniques used for in vitro validation of their immunogenicity. In addition, we outline results from past and on-going vaccine clinical trials and highlight avenues for improvement and future directions.

From Premalignant Biology to Precision Interception: Connecting the Dots with a Curated Collection of Invited Articles.

Nearly all cancers have identifiable histologically defined precursors known as precancers. These precancers offer a window of opportunity to intercept the neoplastic process to prevent its development into invasive cancer. However, lack of knowledge regarding the evolution of precancers and the microenvironmental pressures shaping them precludes efforts to intercept them. Technological developments over the past decade have facilitated the study of precancers at a previously unattainable resolution. Calls for a national PreCancer Atlas effort incorporating these technologies were heeded in 2018, with the launch of the Human Tumor Atlas Network (HTAN) as part of the Beau Biden National Cancer Moonshot. Since then, five funded HTAN groups have focused their efforts on profiling precancers from breast, colon, skin, and lung. In this time, what progress has been made? What is next for HTAN and the field of premalignant biology? And are there lessons that individual investigators and the larger prevention field can learn from this initial effort to accelerate the development of novel early detection methods, risk prediction biomarkers, and interception agents? A special collection of invited reviews by experts in cancer evolution, systems biology, immunology, cancer genetics, preventive agent development, among other areas, attempts to answer these questions.

Current chemoprevention approaches in Lynch syndrome and Familial adenomatous polyposis: a global clinical practice survey.

Background: International chemoprevention preferences and approaches in Lynch syndrome (LS) and APC-associated polyposis, including Familial adenomatous polyposis (FAP) and attenuated FAP (AFAP) have not been previously explored. Aim: To describe current chemoprevention strategies for patients with LS or FAP/AFAP (referred to collectively as FAP) practiced by members of four international hereditary cancer societies through administration of a survey. Results: Ninety-six participants across four hereditary gastrointestinal cancer societies responded to the survey. Most respondents (91%, 87/96) completed information regarding their demographics and practice characteristics relating to hereditary gastrointestinal cancer and chemoprevention clinical practices. Sixty-nine percent (60/87) of respondents offer chemoprevention for FAP and/or LS as a part of their practice. Of the 75% (72/96) of survey respondents who were eligible to answer practice-based clinical vignettes based off of their responses to ten barrier questions regarding chemoprevention, 88% (63/72) of those participants completed at least one case vignette question to further characterize chemoprevention practices in FAP and/or LS. In FAP, 51% (32/63) would offer chemoprevention for rectal polyposis, with sulindac - 300 mg (18%, 10/56) and aspirin (16%, 9/56) being the most frequently selected options. In LS, 93% (55/59) of professionals discuss chemoprevention and 59% (35/59) frequently recommend chemoprevention. Close to half of the respondents (47%, 26/55) would recommend beginning aspirin at time of commencement of the patient's first screening colonoscopy (usually at age 25yrs). Ninety-four percent (47/50) of respondents would consider a patient's diagnosis of LS as an influential factor for aspirin use. There was no consensus on the dose of aspirin (≤100 mg, >100 mg - 325 mg or 600 mg) to offer patients with LS and there was no agreement on how other factors, such as BMI, hypertension, family history of colorectal cancer, and family history of heart disease, would affect the recommendation for aspirin use. Possible harm among older patients (>70 years) was identified as the most common reason to discourage aspirin use. Conclusion: Although chemoprevention is widely discussed and offered to patients with FAP and LS by an international group of hereditary gastrointestinal cancer experts, there is significant heterogeneity in how it is applied in clinical practice.

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

Objective: 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. Design: 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. Results: 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). Conclusion: Screening recommendations for CRC in LS patients should be based on specific MMR variants and should also be tailored to consider patient demographics.

Naproxen chemoprevention induces proliferation of cytotoxic lymphocytes in Lynch Syndrome colorectal mucosa.

Background: Recent clinical trial data from Lynch Syndrome (LS) carriers demonstrated that naproxen administered for 6-months is a safe primary chemoprevention that promotes activation of different resident immune cell types without increasing lymphoid cellularity. While intriguing, the precise immune cell types enriched by naproxen remained unanswered. Here, we have utilized cutting-edge technology to elucidate the immune cell types activated by naproxen in mucosal tissue of LS patients. Methods: Normal colorectal mucosa samples (pre- and post-treatment) from a subset of patients enrolled in the randomized and placebo-controlled 'Naproxen Study' were obtained and subjected to a tissue microarray for image mass cytometry (IMC) analysis. IMC data was processed using tissue segmentation and functional markers to ascertain cell type abundance. Computational outputs were then used to quantitatively compare immune cell abundance in pre- and post-naproxen specimens. Results: Using data-driven exploration, unsupervised clustering identified four populations of immune cell types with statistically significant changes between treatment and control groups. These four populations collectively describe a unique cell population of proliferating lymphocytes within mucosal samples from LS patients exposed to naproxen. Conclusions: Our findings show that daily exposure of naproxen promotes T-cell proliferation in the colonic mucosa, which paves way for developing combination of immunoprevention strategies including naproxen for LS patients.

Worth a Pound of Cure? Emerging Strategies and Challenges in Cancer Immunoprevention.

Cancer immunoprevention applies immunologic approaches such as vaccines to prevent, rather than to treat or cure, cancer. Despite limited success in the treatment of advanced disease, the development of cancer vaccines to intercept premalignant states is a promising area of current research. These efforts are supported by the rationale that vaccination in the premalignant setting is less susceptible to mechanisms of immune evasion compared with established cancer. Prophylactic vaccines have already been developed for a minority of cancers mediated by oncogenic viruses (e.g., hepatitis B and human papillomavirus). Extending the use of preventive vaccines to non-virally driven malignancies remains an unmet need to address the rising global burden of cancer. This review provides a broad overview of clinical trials in cancer immunoprevention with an emphasis on emerging vaccine targets and delivery platforms, translational challenges, and future directions.

Neoadjuvant Pembrolizumab in Localized Microsatellite Instability High/Deficient Mismatch Repair Solid Tumors.

PURPOSE: Pembrolizumab significantly improves clinical outcomes in advanced/metastatic microsatellite instability high (MSI-H)/deficient mismatch repair (dMMR) solid tumors but is not well studied in the neoadjuvant space. METHODS: This is a phase II open-label, single-center trial of localized unresectable or high-risk resectable MSI-H/dMMR tumors. Treatment is pembrolizumab 200 mg once every 3 weeks for 6 months followed by surgical resection with an option to continue therapy for 1 year followed by observation. To continue on study, patients are required to have radiographic or clinical benefit. The coprimary end points are safety and pathologic complete response. Key secondary end points are response rate and organ-sparing at one year for patients who declined surgery. Exploratory analyses include interrogation of the tumor immune microenvironment using imaging mass cytometry. RESULTS: A total of 35 patients were enrolled, including 27 patients with colorectal cancer and eight patients with noncolorectal cancer. Among 33 evaluable patients, best overall response rate was 82%. Among 17 (49%) patients who underwent surgery, the pathologic complete response rate was 65%. Ten patients elected to receive one year of pembrolizumab followed by surveillance without surgical resection (median follow-up of 23 weeks [range, 0-54 weeks]). An additional eight did not undergo surgical resection and received less than 1 year of pembrolizumab. During the study course of the trial and subsequent follow-up, progression events were seen in six patients (four of whom underwent salvage surgery). There were no new safety signals. Spatial immune profiling with imaging mass cytometry noted a significantly closer proximity between granulocytic cells and cytotoxic T cells in patients with progressive events compared with those without progression. CONCLUSION: Neoadjuvant pembrolizumab in dMMR/MSI-H cancers is safe and resulted in high rates of pathologic, radiographic, and endoscopic response, which has implications for organ-sparing strategies.

Germline Cancer Risk Profiles of Patients With Young-Onset Colorectal Cancer: Findings From a Prospective Universal Germline Testing and Telegenetics Program.

BACKGROUND: Colorectal cancer is being increasingly diagnosed in people younger than 50 years. An inheritable cancer predisposition has been reported in 22% of the young-onset cases. Assessment of germline risk is critical for personalized cancer care. OBJECTIVE: The study aimed to implement universal germline cancer risk assessment and testing and to define the germline cancer risk profiles of patients presenting with young-onset disease. DESIGN: This is a prospective cohort study. SETTINGS: This study was conducted at a tertiary-referral academic medical center. PATIENTS: This study included newly diagnosed patients presenting to surgical clinics between September 2019 and February 2021 who were treated on a standardized care pathway including the universal germline risk assessment. INTERVENTIONS: Patients received educational material on young-onset disease, genetic testing, and insurance coverage followed by genetic counseling (either remotely by telegenetics or in person). Consenting patients were assessed on a 47-gene common hereditary cancer panel. MAIN OUTCOME MEASURES: The primary outcome was a proportion of patients with identifiable germline cancer predisposition. RESULTS: Among 500 patients with colorectal cancer, 185 (37%) were 50 years of age or younger (median: 44). A family history was absent for the majority of patients (123; 67%), and in 15 patients, tumors (8.1%) were deficient in DNA mismatch repair. Germline testing was completed in 130 patients (70%); the remainder were pending (7%), deceased (1%), or declined (22%). Pathogenic germline mutations were identified in 25 of 130 (19%) patients: 12 in mismatch repair genes and 13 in other genes. A variant of uncertain significance was found in 23 (18%) patients. Importantly, a pathogenic germline mutation was identified in 12% of the patients without a family history (versus 32% with; p = 0.015) and in 13% of those with proficient mismatch repair colorectal cancers (versus 71% if deficient; p < 0.001). LIMITATIONS: The study is limited by its implementation at a single tertiary academic institution. CONCLUSIONS: One in 5 patients with young-onset disease harbored germline cancer predisposition. This detection rate, coupled with a high level of interest and acceptance from patients and feasibility of implementation, supports universal germline cancer risk assessment in this patient population. See Video Abstract at http://links.lww.com/DCR/B925 . PERFILES DE RIESGO DE CNCER DE LNEA GERMINAL DE PACIENTES CON CNCER COLORRECTAL DE INICIO JOVEN HALLAZGOS DE UN PROGRAMA UNIVERSAL PROSPECTIVO DE PRUEBAS DE LNEA GERMINAL Y TELEGENTICA: ANTECEDENTES:El cáncer colorrectal se diagnostica cada vez más en personas menores de 50 años. Se ha informado una predisposición hereditaria al cáncer en el 22 % de los casos de aparición temprana. La evaluación del riesgo de la línea germinal es fundamental para la atención personalizada del cáncer.OBJETIVO:Implementar la evaluación y las pruebas universales de riesgo de cáncer de línea germinal, y definir los perfiles de riesgo de cáncer de línea germinal de los pacientes que presentan una enfermedad de aparición temprana.DISEÑO:Un estudio de cohorte prospectivo.AJUSTE:Un centro médico académico de referencia terciaria.PACIENTES:Los pacientes recién diagnosticados que se presentaron en clínicas quirúrgicas entre Septiembre de 2019 y Febrero de 2021 fueron tratados en una vía de atención estandarizada que incluye una evaluación de riesgo de línea germinal universal.INTERVENCIÓN:Los pacientes recibieron material educativo sobre enfermedades de aparición temprana, pruebas genéticas y cobertura de seguro, seguido de asesoramiento genético (ya sea a distancia por telegenética o en persona). Los pacientes que dieron su consentimiento fueron evaluados en un panel de cánceres hereditarios comunes de 47 genes.MEDIDA DE RESULTADO PRINCIPAL:Proporción de pacientes con predisposición identificable al cáncer de línea germinal.RESULTADOS:Entre 500 pacientes con cáncer colorrectal, 185 (37%) tenían 50 años o menos (mediana: 44). No había antecedentes familiares en la mayoría (123, 67%) y 15 tumores (8,1%) eran deficientes en la reparación del desajuste de ácido desoxirribonucleico. La prueba de línea germinal se completó en 130 pacientes (70%); el resto estaban pendientes (7%), fallecidos (1%) o declinados (22%). Se identificaron mutaciones patogénicas de la línea germinal en 25 (de 130, 19%) pacientes: 12 en genes de reparación de errores de emparejamiento y 13 en otros genes. Se encontró una variante de significado incierto en 23 (18%) pacientes. Es importante señalar que se identificó una mutación germinal patogénica en el 12% de los pacientes sin antecedentes familiares (frente al 32% con; p = 0,015) y en el 13% de aquellos con cánceres colorrectales competentes en la reparación de errores de emparejamiento (frente al 71% si eran deficientes; p < 0,001).LIMITACIÓN:Implementado en una sola institución académica terciaria.CONCLUSIÓN:Uno de cada cinco pacientes con enfermedad de inicio joven albergaba predisposición al cáncer de línea germinal. Esta tasa de detección, junto con un alto nivel de interés y aceptación por parte de los pacientes y la viabilidad de la implementación, respaldan la evaluación universal del riesgo de cáncer de línea germinal en esta población de pacientes. Consulte el Video Resumen en http://links.lww.com/DCR/B925 . (Traducción-Dr. Yesenia Rojas-Khalil ).

Resistance Mechanisms to Anti-Epidermal Growth Factor Receptor Therapy in RAS/RAF Wild-Type Colorectal Cancer Vary by Regimen and Line of Therapy.

PURPOSE: Acquired resistance to anti-epidermal growth factor receptor (EGFR) inhibitor (EGFRi) therapy in colorectal cancer (CRC) has previously been explained by the model of acquiring new mutations in KRAS/NRAS/EGFR, among other MAPK-pathway members. However, this was primarily on the basis of single-agent EGFRi trials and little is known about the resistance mechanisms of EGFRi combined with effective cytotoxic chemotherapy in previously untreated patients. METHODS: We analyzed paired plasma samples from patients with RAS/BRAF/EGFR wild-type metastatic CRC enrolled in three large randomized trials evaluating EGFRi in the first line in combination with chemotherapy and as a single agent in third line. The mutational signature of the alterations acquired with therapy was evaluated. CRC cell lines with resistance to cetuximab, infusional fluorouracil, leucovorin, and oxaliplatin, and SN38 were developed, and transcriptional changes profiled. RESULTS: Patients whose tumors were treated with and responded to EGFRi alone were more likely to develop acquired mutations (46%) compared with those treated in combination with cytotoxic chemotherapy (9%). Furthermore, contrary to the generally accepted hypothesis of the clonal evolution of acquired resistance, we demonstrate that baseline resistant subclonal mutations rarely expanded to become clonal at progression, and most remained subclonal or disappeared. Consistent with this clinical finding, preclinical models with acquired resistance to either cetuximab or chemotherapy were cross-resistant to the alternate agents, with transcriptomic profiles consistent with epithelial-to-mesenchymal transition. By contrast, commonly acquired resistance alterations in the MAPK pathway do not affect sensitivity to cytotoxic chemotherapy. CONCLUSION: These findings support a model of resistance whereby transcriptomic mechanisms of resistance predominate in the presence of active cytotoxic chemotherapy combined with EGFRi, with a greater predominance of acquired MAPK mutations after single-agent EGFRi. The proposed model has implications for prospective studies evaluating EGFRi rechallenge strategies guided by acquired MAPK mutations, and highlights the need to address transcriptional mechanisms of resistance.