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Objective: To determine the frequency of mismatch repair deficiency in colorectal carcinoma determined by immunohistochemistry. Study Design: Cross-sectional study. Place and Duration of Study: Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, from Aug 2018 to Jan 2019. Methodology: A total of 101 patients of adenocarcinoma of colorectum who underwent surgical resections and their characteristic and clinical data were recorded. Immunohistochemical stains were performed using antibodies MLH1, MSH2, PMS2 and MSH6. Results were interpreted and mismatch repair deficiency status of all patients was determined. Patients with loss of expression for MLH1, MSH2, PMS2 and MSH6 antibodies were observed and noted. Results: In this study, out of 101 patients with CRC, 71 (70.3%) were male and 30 (29.7%) female. The mean age was (54 years ± 15.9). Amongst the 101 cases loss of immunohistochemical staining for MMR proteins was noted in 19 patients (18.8%). The combined loss of all four antibodies was seen in one case, loss of MLH1 and PMS2 in 7, MSH2 and MSH6 in 5 and MLH1 only in 6 patients. However, no mismatch repair deficiency was detected in remaining 82 cases. According to statistical analysis no significant association between mismatch repair deficiency and variables was found. Conclusion: The frequency of mismatch repair deficiency in colorectal carcinoma patients was found to be 18.8% in our population.

Neoadjuvant chemotherapy (NACT) before radical gastrectomy is preferred for locally advanced gastric cancer (GC). However, clinical practices demonstrate that a considerable proportion of GC patients do not benefit from NACT, largely due to the lack of biomarkers for patient selection and prognosis prediction. A recent study revealed that patients with microsatellite instability-high (MSI-H) may be resistant to NACT, however, most tumors in Chinese GC patients (~ 95%) are characterized by microsatellite stability (MSS). Here, we aimed to discover new molecular biomarkers for this larger population. We performed whole-exome sequencing on 46 clinical samples (pre- and post-treatment) from 30 stage II/III MSS GC patients whose response to NACT was rigorously defined. Serum tumor markers (TMs), including AFP, CEA, CA199, CA724 and CA242 were measured during the course. High tumor mutation burden (TMB-H) and 19q12 amplification (19q12 +) were positively associated with the NACT response. When TMB and 19q12 amplification were jointly analyzed, those with TMB-H or 19q12 + showed favorable response to NACT (p = 0.035). Further, TMB-H was negatively correlated with ypN stage, lymph node metastasis, and macrophage infiltration. Patients with TMB-H showed better disease-free survival (DFS) than those with TMB-L (P = 0.025, HR = 0.1331), and this was further validated using two larger GC datasets: TCGA-STAD (p = 0.004) and ICGC-CN (p = 0.045). The combination of TMB-H and 19q12 + can serve as an early indicator of response to NACT. Superior to traditional clinical indicators, TMB-H is a robust and easily accessible candidate biomarker associated with better DFS, and can be evaluated at the time of diagnosis.

BACKGROUND Rectal cancer in adolescents and young adults (age ≤39) is increasing. Early diagnosis is a challenge in this subset of patients. OBJECTIVE This study aims to analyze the presentation pattern and outcomes of sporadic rectal cancer in adolescents and young adults. DESIGN This is a retrospective study. SETTING This study was conducted at 3 European tertiary centers. PATIENTS Data on adolescents and young adults operated on for sporadic rectal cancer (January 2008 through October 2019) were analyzed. To compare outcomes, adolescents and young adults were matched to a group of patients aged ≥40 operated on during the same period. MAIN OUTCOME MEASURES The primary outcomes measured were clinical presentation and long-term outcomes. RESULTS Sporadic rectal cancers occurred in 101 adolescents and young adults (2.4%; mean age, 33.5; range, 18-39); 51.5% were male, and a smoking habit was reported by 17.8% of patients. The rate of a family history for colorectal cancer was 25.7%, and of these patients, 24.7% were obese. Diagnosis based on symptoms was reported in 92.1% patients, and the mean time from first symptoms to diagnosis was 13.7 months. The most common symptom at diagnosis was rectal bleeding (68.8%), and 12% and 34% of the adolescents and young adults presented with locally advanced or metastatic disease at diagnosis. Consequently, 68.3% and 62.4% adolescents and young adults received neoadjuvant and adjuvant treatments. The rate of complete pathological response was 24.1%; whereas 38.6% patients had stage IV disease, and 93.1% were microsatellite stable. At a mean follow-up of 5 years, no difference in cancer-specific survival, but a lower disease-free survival was reported in adolescents and young adults (p < 0.0001) vs the matched group. Adolescents and young adults with stages I to II disease had shorter cancer-specific survival and disease-free survival (p = 0.006; p < 0.0001); with stage III disease, they had a shorter disease-free survival (p = 0.01). LIMITATIONS This study was limited by its observational, retrospective design. CONCLUSIONS The significantly delayed diagnosis in adolescents and young adults may have contributed to the advanced disease at presentation and lower disease-free survival, even at earlier stages, suggesting a higher metastatic potential than in older patients. See Video Abstract at http://links.lww.com/DCR/B537. CNCER DE RECTO EN PACIENTES ADOLESCENTES Y ADULTOS JVENES CUADRO DE PRESENTACIN CLNICA Y COMPARACIN DE DESENLACES POR CASOS EMPAREJADOS ANTECEDENTES:El cancer de recto en adolescentes y adultos jovenes (edad ≤ 39) esta aumentando. El diagnostico temprano es un desafio en este subgrupo de pacientes.OBJETIVO:Analizar el cuadro de presentacion y los desenlaces en adolescentes y adultos jovenes con cancer de recto esporadico.DISENO:Estudio retrospectivo.AMBITO:Tres centros europeos de tercer nivel.PACIENTES:Se analizaron los datos de adolescentes y adultos jovenes operados de cancer de recto esporadico (enero de 2008 - octubre de 2019). Para comparar los desenlaces se emparejo a adolescentes y adultos jovenes con un grupo de pacientes mayores de 40 anos operados en el mismo periodo de tiempo.PRINCIPALES VARIABLES ANALIZADAS:Cuadro clinico, resultados a largo plazo.RESULTADOS:Los canceres de recto esporadicos en adolescentes y adultos jovenes fueron 101 (2,4%, edad media: 33,5, rango 18-39). El 51,5% eran hombres, el 17,8% de los pacientes fumaba. El 25,7% tentia antecedentes familiares de cancer colorrectal. El 24,7% eran obesos. El diagnostico con base en los sintomas se informo en el 92,1% de los pacientes, el tiempo promedio desde los primeros sintomas hasta el diagnostico fue de 13,7 meses. El sintoma mas comun en el momento del diagnostico fue el sangrado rectal (68,8%). 12% y 34% de adolescentes y adultos jovenes presentaron enfermedad localmente avanzada o metastasica en el momento del diagnostico. Por lo tanto, el 68,3% y el 62,4% de adolescentes y adultos jovenes recibieron neoadyuvancia y adyuvancia. La tasa de respuesta patologica completa fue del 24,1%; mientras que el 38,6% estaban en estadio IV. El 93,1% eran microsatelite estable. Con una media de seguimiento de 5 anos, no se observaron diferencias en la sobrevida especifica del cancer, pero se informo una menor sobrevida libre de enfermedad en adolescentes y adultos jovenes (p

Colorectal cancer represents the second leading cause of cancer-related death worldwide. The therapeutic field of immuno-oncology has rapidly gained momentum, with strikingly promising results observed in clinical practice. Increasing emphasis has been placed on the role of the immune response in tumorigenesis, therapy and predicting prognosis. Enhanced understanding of the dynamic and complex tumour-immune microenvironment has enabled the development of molecularly directed, individualised treatment. Analysis of intra-tumoural lymphocyte infiltration and the dichotomisation of colorectal cancer into microsatellite stable and unstable disease has important therapeutic and prognostic implications, with potential to capitalise further on this data. This review discusses the latest evidence surrounding the tumour biology and immune landscape of colorectal cancer, novel immunotherapies and the interaction of the immune system with each apex of the tripartite of cancer management (oncotherapeutics, radiotherapy and surgery). By utilising the synergy of chemotherapeutic agents and immunotherapies, and identifying prognostic and predictive immunological biomarkers, we may enter an era of unprecedented disease control, survivorship and cure rates.

CASE SUMMARY A 65-year-old man presents with new liver lesions on surveillance imaging 2 years after a right hemicolectomy for cecal adenocarcinoma. The primary tumor was pT3N1, microsatellite stable, and KRAS wild type. He completed adjuvant FOLFOX. His CEA level is 22 ng/mL. There are two 1.5-cm lesions in the right lobe near the dome of the liver and a 4-cm lesion in segment II. No luminal recurrence is detected endoscopically, and there is no evidence of peritoneal or pulmonary disease.

Aya Alsayed,1 Salem E Salem,1 Mostafa M El Serafi,1 Mona S Abdellateif,2 Abdel-Rahman N Zekri,3 Marwa Mohanad,4 Abeer A Bahnassy5 1Department of Medical Oncology, National Cancer Institute, Cairo University, Cairo, 11976, Egypt; 2Medical Biochemistry and Molecular Biology, Cancer Biology Department, National Cancer Institute, Cairo University, Cairo, 11976, Egypt; 3Molecular Virology and Immunology Unit, Cancer Biology Department, National Cancer Institute, Cairo University, Cairo, 11976, Egypt; 4Biochemistry Department, College of Pharmaceutical Sciences and Drug Manufacturing, Misr University for Science and Technology, Giza, 12945, Egypt; 5Pathology Department, National Cancer Institute, Cairo University, Cairo, 11976, EgyptCorrespondence: Abeer A BahnassyPathology Department, National Cancer Institute, Cairo University, Cairo, EgyptFax +20 223644720Email chaya2000@hotmail.ComBackground: Microsatellite instability (MSI) and circulating tumor cells (CTCs) play important roles in the diagnosis, prognosis and management of colorectal cancer (CRC) patients.Methods: CTCs and MSI were assessed in the blood and representative tumor tissues of 100 CRC patients by flow cytometry (FCM) and PCR amplification. The data were correlated to relevant clinicopathological features of the patients, progression-free survival (PFS) and overall survival (OS) rates.Results: MSI-high was detected in 44 (44.0%) patients, MSI-low in 37 (37%), and microsatellite stable (MSS) in 19 (19.0%) patients (P=0.007). The baseline CTCs count (< 4 cells/7mL blood) was reported in 39% of the patients, and CTCs ≥ 4 cells/7mL blood in 61% of the patients (P=0.028). Improved PFS and OS rates were associated significantly with MSI-high (P< 0.001), decreased CTC levels during the course of treatment (P< 0.001) and post-treatment CTCs (P=0.008). There was no significant association between MSI-high and PFS or OS in early-stage patients (P=0.187 and P=0.187; respectively); however, it was associated significantly with better PFS and OS in late-stage patients (P< 0.001). Multivariate analysis showed that only a change in serial CTC levels is considered an independent prognostic factor for OS (P< 0.012). Post-treatment CTCs level, serial CTCs level changes during the course of treatment, lymph nodes and distant metastasis were independent prognostic factors for PFS (P< 0.001, P= 0.047, P=0.001 and P< 0.001; respectively).Conclusion: MSI and CTCs could be used as accurate, reliable and sensitive diagnostic and prognostic biomarkers for CRC patients’ survival rates and outcomes.Keywords: circulating tumor cells, microsatellite instability, colorectal cancer, response to treatment, survival rates

Immune checkpoint inhibitors changed treatment paradigms across several malignancies. With the exception of tumors with microsatellite instability (MSI-H), gastrointestinal cancers have been largely resistant to these agents. Herein, we review the data supporting the use of immunotherapy for patients with (MSI-H) colorectal tumors. We discuss ongoing research and answered questions regarding resistance and sequence of use of these agents for this disease. We discuss ongoing research efforts to augment activity of these agents in microsatellite stable colorectal cancer. We also provide an overview of the data and ongoing studies immune checkpoint inhibitors in the treatment of anal cancer.

Supplemental Digital Content is available in the text., Grade 3 (G3, poorly differentiated) is an important treatment-decision factor in stage II colon cancer, but no unified diagnostic criteria are established. According to previous studies, an intratumoural poorly differentiated area with no glandular formation (POR) that fills the microscopic field of a ×40 objective lens was an essential factor that defined G3. We aimed to prospectively validate this in a randomized controlled study of adjuvant chemotherapy (SACURA trial). We enrolled 991 patients with stage II colon cancer. POR was graded according to the ×40 objective lens rule and the intensity of poorly differentiated clusters (GradePOR), and its prognostic power was compared with that of the conventional tumor grade on the basis of predominant histology rule (Gradeconv). According to GradePOR, 313, 526, and 152 tumors were classified as G1POR, G2POR, and G3POR, respectively, and the 5-year relapse-free survival (RFS) rates were 91.1%, 82.9%, and 74.7%, respectively (P

BackgroundFor a majority of patients with metastatic colorectal cancer (mCRC) with MS stable (MSS) or mismatch repair proficient (pMMR), the role of immunotherapy is undetermined. This study investigated the efficacy and safety of camrelizumab when added to XELOX chemotherapy plus bevacizumab or regorafenib as first-line therapy for mCRC.Materials and MethodsMedical records of mCRC patients who received camrelizumab and XELOX plus bevacizumab or regorafenib at the First Hospital of Quanzhou Affiliated to Fujian Medical University between June 1, 2019, and April 30, 2021, were retrospectively collected. The objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and side effects of the drug were recorded and reviewed.ResultsTwenty-five eligible patients received combination therapy, including bevacizumab in 19 patients and regorafenib in 6. Twenty-one patients had pMMR/MSS and one MSI-H. Of the 25 patients who could be evaluated for efficacy, 18 (72%) achieved PR, 6 (24%) achieved SD, and 1 (4%) achieved PD. The ORR and DCR were 72% (18/25) and 96% (24/25), respectively. The median progression-free survival (PFS) was 11.2 months (95% CI 8.9–13.9), and OS had not yet been reached. The combination regimen of regorafenib in six (24%) patients was unassociated with treatment outcomes. Most AEs were either grade 1 or 2, and treatment-related grade 3 toxicities were observed in 8/25 (32%) patients.ConclusionCamrelizumab combined with XELOX plus bevacizumab or regorafenib was feasible, producing high rates of responses as first-line therapy in unselected Chinese patients with MSS mCRC. The toxicities were generally tolerable and manageable. Prospective randomized trials with large sample sizes are needed to evaluate these findings.

BackgroundMicrosatellite stability (MSS) or mismatch repair proficient (pMMR) metastatic colorectal cancer (mCRC) is resistant to immune checkpoint inhibitors. Studies have shown that antiangiogenic drugs combined with programmed death receptor-1 (PD-1) inhibitors can improve immunosuppression. The purpose of this study was to compare the efficacy of fruquintinib combined with PD-1 inhibitor (FP) and regorafenib combined with PD-1 inhibitor (RP) in the treatment of advanced mCRC with MSS or pMMR.Materials and MethodsWe retrospectively collected advanced MSS or pMMR mCRC patient data from The Second Affiliated Hospital of Nanchang, China, from June 2019 to March 2021. Then, we analyzed and compared the efficacy and safety of FP and RP.ResultsA total of 51 patients who met the criteria were divided into FP (n = 28) and RP groups (n = 23). The overall response rate of the FP and RP groups was 7.1% and 8.7% and the disease control rate was 89.3% and 56.5%, respectively. The median progression-free survival (PFS) time was higher in the FP group than in the RP group (6.4 vs. 3.9 months, respectively; P = 0.0209). Patients with no liver metastasis, KRAS wild type, and left colon tumor may benefit from FP. Eight patients (15.7%) had grade 3 toxicity related to treatment. Cox multivariate regression analysis showed that the treatment method was an independent risk factor for median PFS time.ConclusionOur study indicates that FP could improve PFS time of patients with advanced mCRC compared with RP.

Patients with colorectal liver metastases (CLM) commonly receive neoadjuvant chemotherapy (NACT) prior to surgical resection. NACT may induce immunogenic cell death with subsequent recruitment of T-cells to the tumor microenvironment, which could be exploited by immune checkpoint inhibition (ICI). In theory, this could expand the use of ICI to obtain responses also in microsatellite stable colorectal cancer, but evidence to suggest optimal treatment schedules are lacking. In this study, densities of total-, cytotoxic-, helper- and regulatory T-cells were quantified by immunohistochemistry in resected CLM from 92 patients included in the OSLO-COMET trial (NCT01516710). All but one patient had microsatellite stable tumors (91/92). Associations between T-cell densities and clinicopathological parameters were analyzed. Fluoropyrimidine-based NACT (in most cases with addition of oxaliplatin or irinotecan) was administered to 45 patients completed median 8 weeks prior to surgical resection. No overall association was found between NACT administration and intratumoral T-cell densities. However, within the NACT group, a short time interval (

Purpose:To analytically and clinically validate microsatellite instability (MSI) detection using cell-free DNA (cfDNA) sequencing.Experimental Design:Pan-cancer MSI detection using Guardant360 was analytically validated according to established guidelines and clinically validated using 1,145 cfDNA samples for which tissue MSI status based on standard-of-care tissue testing was available. The landscape of cfDNA-based MSI across solid tumor types was investigated in a cohort of 28,459 clinical plasma samples. Clinical outcomes for 16 patients with cfDNA MSI-H gastric cancer treated with immunotherapy were evaluated.Results:cfDNA MSI evaluation was shown to have high specificity, precision, and sensitivity, with a limit of detection of 0.1% tumor content. In evaluable patients, cfDNA testing accurately detected 87% (71/82) of tissue MSI-H and 99.5% of tissue microsatellite stable (863/867) for an overall accuracy of 98.4% (934/949) and a positive predictive value of 95% (71/75). Concordance of cfDNA MSI with tissue PCR and next-generation sequencing was significantly higher than IHC. Prevalence of cfDNA MSI for major cancer types was consistent with those reported for tissue. Finally, robust clinical activity of immunotherapy treatment was seen in patients with advanced gastric cancer positive for MSI by cfDNA, with 63% (10/16) of patients achieving complete or partial remission with sustained clinical benefit.Conclusions:cfDNA-based MSI detection using Guardant360 is highly concordant with tissue-based testing, enabling highly accurate detection of MSI status concurrent with comprehensive genomic profiling and expanding access to immunotherapy for patients with advanced cancer for whom current testing practices are inadequate.See related commentary by Wang and Ajani, p. 6887

RATIONALE: Loss of DNA mismatch repair function has long been known in various malignancies, particularly colorectal cancer. However, microsatellite instability (MSI) testing was rarely requested in Thailand. Recently, the US Food and Drug Administration (FDA) has approved pembrolizumab, an antibody to PD-1 receptor, as an alternative treatment for high MSI (MSI-H) and/or MMR (mismatch repair)-deficient solid tumors. We report our recent observation on MSI testing in Thailand. MATERIALS AND METHODS: Data was collected from Chulalongkorn GenePRO Center, Faculty of Medicine, Chulalongkorn University, during July 2013 and July 2017. MSI testing was performed, using 5 microsatellite markers (BAT-25, BAT-26, D2S123, D5S346 and D17S250). The number, source, and result of samples underwent MSI assay were analyzed. RESULTS: Requests for MSI testing have increased significantly in recent years. The shift started in 2015 when the MMR status was found to predict clinical benefit with the immune checkpoint blockade. There were 118 (75.2%) colorectal, 11 (7%) gastric, and 28 (17.8%) other cancers tested. MSI-H, MSI-L, and microsatellite stable (MSS) tumors were detected in 18 (11.5%), 11 (7%), and 128 (81.5%) patients, respectively. Of the 18 MSI-H cancers; 13 (72.2%), 4 (22.2%), and 1 (5.6%) were colorectal, gastric, and gynecologic malignancy, respectively. BAT25 and BAT26 markers were unstable in all MSI-H tumors. CONCLUSION: We have experienced increasing demand for MSI testing in Thai patients at Chulalongkorn GenePRO Center. Colorectal cancers were most frequently tested, and accounted for the highest percentage among the MSI-H cancers. Keywords: microsatellite instability, mismatch repair, immunotherapy, cancers Address Correspondence to author: Chinachote Teerapakpinyo, PhD Chulalongkorn GenePRO Center,Faculty of Medicine, Chulalongkorn University 1873, Rama 4 Rd., Pathumwan, Bangkok 10330, Thailand. email: Chinachote.T@chula.ac.th Received: May 28, 2018 Revision received: June 1, 2018 Accepted after revision: July 17, 2018 BKK Med J 2018;14(2): 1-5. DOI: 10.31524/bkkmedj.2018.09.001

A small subset of patients with proficient mismatch repair (pMMR)/microsatellite stable (MSS)-colorectal cancer (CRC) benefit from immunotherapy with anti-programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade. Therefore, the aim of the current study was to evaluate the immune status of patients with pMMR/microsatellite instability-low (MSI-L)/MSS-CRC and deficient MMR (dMMR)/MSI-high (MSI-H)-CRC in order to identify responders to anti-PD-1/PD-L1 inhibitors. The current study used a dataset downloaded from The Cancer Genome Atlas (TCGA) as well as 219 clinical tissue samples to investigate the infiltrating grade of cluster of differentiation (CD) 4 and CD8 tumor infiltrating lymphocytes (TILs), the expression levels of PD-L1 and PD-L2, the interferon-γ (IFN-γ) and CD8 T effector gene signatures, and the phosphorylated signal transducer and activator of transcription 1 (p-STAT1) status in patients with pMMR/MSI-L/MSS-CRC and dMMR/MSI-H-CRC. Analysis of TCGA dataset revealed that the mRNA expression levels of PD-L1 and PD-L2, the IFN-γ gene signature and the CD8 T effector gene signature were significantly upregulated in MSI-H tumors compared with MSI-L/MSS tumors. Additionally, a subpopulation of patients with upregulation of the IFN-γ and CD8 T effector gene signatures was observed in those with MSI-L/MSS-CRC. Immunohistochemical staining of the clinical samples revealed a subpopulation of patients with pMMR-CRC that were positive for PD-L1 and p-STAT1, and whom had levels of elevated CD8(+) and CD4(+) TILs infiltration similar to those observed in patients with dMMR-CRC. The results obtained in the current study suggested that a subpopulation of patients with MSI-L/MSS-CRC and pMMR-CRC with upregulated IFN-γ and CD8 T effector gene signatures may benefit from immunotherapy with antibodies against PD-1 and PD-L1.

Immune checkpoint blockade has emerged as an effective therapeutic strategy for patients with advanced cancer. Identification of biomarkers associated with treatment efficacy will help to select patients more likely to respond to this approach. High levels of microsatellite instability, tumor expression of PD-L1, high tumor mutation burden, and increased tumor-infiltrating lymphocytes have all been associated with response to checkpoint inhibitor blockade. The purpose of this study was to determine if a subset of microsatellite-stable endometrioid endometrial carcinomas have higher immune cell infiltrates and/or expression of PD-L1. PD-L1 expression and characterization of immune cell infiltrates were analyzed in 132 microsatellite stable, FIGO grade 2 endometrioid carcinomas. PD-L1 was positive in 48% (63/132) of the tumors. Tumor cell expression of PD-L1 was significantly associated with lymphatic/vascular invasion and deep myometrial invasion. PD-L1 expression was especially prominent at the invasive front and in foci of tumor-associated squamous metaplasia. Twenty-one cases (16% of the total) with more diffuse and/or especially strong PD-L1 expression were identified. This PD-L1 high subset was associated with significantly higher numbers of tumor-associated CD3+ and CD8+ lymphocytes. Only one tumor in the PD-L1 high subset harbored a POLE mutation. PTEN immunohistochemical loss, a common event in endometrioid-type endometrial carcinoma and associated with local immune suppression in melanoma, was not associated with PD-L1 expression or lymphocyte/macrophage infiltration of the tumor. These results suggest that a subset of microsatellite-stable endometrial cancers has higher expression of PD-L1 and increased tumor-associated CD3+ and CD8+ lymphocytes, characteristics more commonly associated with endometrial cancers with high levels of microsatellite instability. These results suggest that screening strategies to select only microsatellite instability-high advanced endometrial cancers for checkpoint inhibitor therapy might exclude patients who could potentially benefit from this therapeutic approach.

Gastric malignancy – one of the five most deadliest types of cancer – exceeds annual cases by a million worldwide since 2017. Automated screening tools may help speed up the screening and clinical procedures. In this paper, we propose a binary classification approach to classify gastrointestinal cancer tissues, namely Microsatellite Instable (MSI) and Microsatellite Stable (MSS) through stacked generalization based ensemble Deep Neural Network (DNN)11Authors contributed equally to the work.. Using a dataset of size 192, 315 images, we achieve an overall accuracy of 94.91% and sensitivity of 95.95%. Our results outperform previous works.

AimsAnalysis of microsatellite instability (MSI) is strongly recommended in endometrial cancer (EC) and colorectal cancer to screen for Lynch syndrome, to predict prognosis and to determine optimal treatment and follow-up. In a large monoinstitutional series of ECs, we evaluated the reliability and accuracy of Idylla assay, a rapid, fully automated system to detect MSI, and we compared its performance with two routine reference methods.MethodsWe evaluated MSI status in 174 formalin-fixed, paraffin-embedded EC tissue samples using immunohistochemistry (IHC) for mismatch repair (MMR) proteins and Idylla assay. Samples with discordant or equivocal results were analysed with a third technique, the Promega MSI kit.ResultsIdylla MSI assay and IHC were highly concordant (overall agreement: 154/170=90.59%, 95% CI 85.26% to 94.12%). However, in four samples, MMR-IHC staining was equivocal; moreover, 16 cases showed discordant results, that is, MMR deficient using IHC and microsatellite stable using Idylla. These 20 samples were reanalysed using the MSI-Promega kit, which showed the same results of Idylla assay in 18/20 cases (overall agreement: 90%, 95% CI 69.90% to 97.21%).ConclusionsOur results suggest that IHC is an efficient method to determine MMR status in ECs. However, the Idylla MSI assay is a rapid and reliable tool to define MSI status, and it could represent a valuable alternative to conventional MSI-PCR methods.

Objective To determine the cost-effectiveness of lenvatinib plus pembrolizumab (LP) in patients with microsatellite stable (MSS), recurrent, pretreated endometrial cancer (EC). Methods A decision analysis model was created to evaluate the cost-effectiveness of LP relative to doxorubicin, pegylated liposomal doxorubicin (PLD), and bevacizumab in patients with recurrent pretreated MSS EC. Published data was used to estimate quality adjusted life years (QALYs) and drug cost estimates were obtained using average wholesale prices. A health state utility (HSU) penalty of −0.10 was applied to the LP group to account for treatment toxicity. Incremental cost-effectiveness ratios (ICERs) were calculated to determine cost/QALY. The willingness to pay threshold (WTP) was set at $100,000 per QALY saved. Sensitivity analyses were performed on cost, effectiveness, and HSU penalty for LP. Results Costs of treatment with doxorubicin, PLD, and bevacizumab are $23.7 million (M), $56.9 M, and $250.8 M respectively. Cost of treatment with LP is $1.8 billion. Relative to doxorubicin, the ICERs for PLD, bevacizumab, and LP are $56,808, $345,824, and $1.6 M respectively. A sensitivity analysis varying the cost of LP shows that if the combined drug cost decreases from over $58,000 to less than $11,000 per cycle, this strategy would be cost-effective. Eliminating the HSU penalty for LP decreased the ICER $1.0 M while increasing the penalty to −0.20 increased the ICER to $3.7 M. Conclusions LP is not cost-effective in patients with recurrent pretreated, MSS EC. A dramatic reduction in cost of LP is required for this novel strategy to be cost-effective.

Background/aim The majority of colorectal cancer (CRC) cases, which are microsatellite stable (MSS) and do not harbor mismatch repair deficiency/microsatellite instability, are resistant to immunotherapy. Identification of patients with exceptional responses in MSS CRC and predictive biomarkers is an unmet need that needs to be addressed. Case report We report three cases of MSS CRC with durable clinical benefit from immunotherapy with anti-PD-1 checkpoint inhibitors. Two cases bear a POLE P286R mutation, which has been associated with lack of immunotherapy response in MSS CRC. Two cases bear alterations in Ataxia-Telangiectasia Mutated (ATM) which may contribute to observed responses, including interaction with a co-administered intratumoral stimulator of interferon genes (STING) pathway agonist in one patient. Conclusion Novel DNA damage repair alterations, including mutations in ATM, can provide insight into additional mechanisms by which genomic alterations can sensitize MSS CRC to diverse immunotherapies.

BackgroundTumor sidedness as a prognostic factor in advanced stage colon cancer (CC) is well established. The impact of tumor sidedness on the clinical outcomes of stage II and III CC has not been well studied.MethodsThe National Cancer Database (NCDB) was utilized to identify patients with pathological stage II and III primary adenocarcinoma of the colon from 2010 to 2015 using ICD-O-3 morphology and topography codes: 8140-47, 8210-11, 8220-21, 8260-63, 8480-81, 8490 and C18.0, 18.2,18.3, 18.5,18.6, 18.7. Univariate (UVA) and multivariable (MVA) survival analyses and Kaplan–Meier Curves with Log-rank test were utilized to compare overall survival (OS) based on tumor location and treatment received.ResultsA total of 35,071 patients with stage II (n = 17,629) and III (n = 17,442) CC were identified. 51.3% female; 81.5% Caucasian; median age 66 (range, 18–90). Majority of stage II and III tumors were right sided, 61.2% (n = 10,794) and 56.0% (n = 9,763). Microsatellite instability high (MSI-H) was more common in stage II compared to III, 23.3% (n = 4,115) vs 18.2% (n = 3,171) (p < 0.0001). In stage II MSI-H CC right was more common than left, 78.3% (n = 3223) vs 21.7% (n = 892). There was no significant difference in survival between stage II MSI-H left vs right (5-year OS 76.2 vs 74.7%, p = 0.1578). Stage II MSS CC right was more common than left, 56.0% (n = 7571) vs 44.0% (n = 5943), and survival was better in the left vs right (5-year OS 73.2 vs 70.8%, p = 0.0029). Stage III MSI-H CC was more common in the right than in the left, 75.6% (n = 2,397) vs 24.4% (n = 774) and survival was better in the left (5-year OS 62.5 vs 56.5%, p = 0.0026). Stage III MSS CC was more common in the right than in the left, 51.6% (n = 7,366) vs 48.4% (n = 6,905), and survival was better in the left vs right (5-year OS 67.0 vs 54.4%, p < 0.001).ConclusionSurvival was better in left sided tumors compared to right in stage II MSS, stage III MSS, and stage III MSI-H CC.

BackgroundMicrosatellite-stable (MSS) and instability-low (MSI-L) metastatic colorectal cancer (mCRC) are typically characterised as ”immune-excluded/desert” tumour microenvironments lacking T-cell infiltration. Anti-PD-1 monotherapy has little clinical benefit in MSS/MSI-L mCRC1 and knowledge of the effects of PD-1 inhibition on T-cell activation/infiltration in this population is limited. Novel combination therapies to overcome anti-PD-1 resistance are required. SPICE is a multicentre, open-label, phase 1 study of the tumour-selective chimeric Ad11/Ad3 group B oncolytic adenovirus enadenotucirev plus nivolumab in patients with metastatic/advanced epithelial tumours refractory to standard therapy. Preliminary data from patients with MSS/MSI-L mCRC demonstrated a median overall survival of 14 months, manageable tolerability and intratumoural T-cell infiltration.2 Here we characterise the immunological effects of tumour re-engineering with enadenotucirev in combination with nivolumab in patients with MSS/MSI-L mCRC.MethodsPatients received increasing doses and/or cycles of intravenous enadenotucirev followed by up to 8 cycles of nivolumab as previously described.2 Wherever possible, pre- and post-treatment (~5 weeks post-first enadenotucirev) biopsies were collected; samples were analysed using immunohistochemistry and automated image analysis. Peripheral blood mononuclear cell immunophenotyping (multiparameter flow cytometry) and serum cytokines were assessed at multiple times.Results43 patients with mCRC were treated (86% MSS/MSI-L; 14% unknown). Among the 13 patients (12/13 MSS/MSI-L; 1/13 unknown) with matched biopsies, 11 had increased intratumoural and stromal CD8+ T-cell infiltration in post-treatment biopsies (median [Q1-Q3] fold changes 6.5× [1.5–25.4] and 1.9× [1.5–3.9], respectively; figure 1). CD4+ T-cell density increased in 10/13 patients and 8/13 patients had increased proportions of PD-L1+ immune cells. Increases in CD8 T-cell proliferation (Ki67; 7/9 patients) and cytolytic activity (Granzyme B; 7/13 patients) markers were seen. 4/13 patients converted from a ”desert” to an ”inflamed” immune phenotype (pathologist scored CD8/pan-cytokeratin staining). Immunophenotyping showed trends towards increased T-cell activation (CD38+ and HLA-DR+ CD8+ T cell populations) post-treatment (9/10 patients), including in one patient who had only received enadenotucirev prior to sampling. Persistent increases in inflammatory cytokines (IFNγ, IL-12p70, IL-17a) were seen in two patients from ~Day 15, including one who achieved a sustained objective response.Abstract 342 Figure 1Tumour immune cell infiltration following treatment with enadenotucirev plus nivolumabConclusionsThese data show that intravenous enadenotucirev plus nivolumab can induce immune infiltration/activation within MSS/MSI-L mCRC. These encouraging findings suggest that immune activation can be achieved even in ”immune-excluded/desert” tumours. SPICE has been closed following completion of dose-escalation. Efforts are now focused on the development of next-generation variants of enadenotucirev designed to further re-programme the tumour microenvironment by expressing immune-enhancer transgenes (T-SIGn vectors); these studies are ongoing (NCT04830592, NCT04053283, NCT03852511).AcknowledgementsThis study was funded by PsiOxus Therapeutics Limited and Bristol Myers Squibb. Medical writing support: Lola Parfitt, MRes, of PsiOxus Therapeutics Limited.Trial RegistrationEudraCT number2017-001231-39NCT number: NCT02636036ReferencesKawazoe A, Kuboki Y, Shinozaki E, et al. Multicenter phase I/II trial of napabucasin and pembrolizumab in patients with metastatic colorectal cancer (EPOC1503/SCOOP trial). Clin Cancer Res 2020;26:5887–5894.Fakih M, Wang D, Harb W, et al. SPICE: a phase I multicenter study of enadenotucirev in combination with nivolumab in tumors of epithelial origin: an analysis of the metastatic colorectal cancer patients in the dose escalation phase. Ann Oncol 2019:30(suppl_5):v252.Ethics ApprovalThe study was approved by the WCG Institutional Review Board (study approval number 20152656), UCLA Institutional Review Board (study approval number IRB#15-002010), Vanderbilt Institutional Review Board (study approval number IRB #171453) and Henry Ford Institutional Review Board (study approval number IRB #10349).

Background: In patients with synchronous colorectal cancer (SCRC), understanding the underlying molecular behavior of such cases is mandatory for designing individualized therapy. The aim of this paper is to highlight the importance of transdisciplinary evaluation of the pre- and post-operative assessment of patients with SCRCs, from imaging to molecular investigations. Methods: Six patients with SCRCs presented with two carcinomas each. In addition to the microsatellite status (MSS), the epithelial mesenchymal transition was checked in each tumor using the biomarkers β-catenin and E-cadherin, same as KRAS and BRAF mutations. Results: In two of the patients, the second tumor was missed at endoscopy, but diagnosed by a subsequent computed-tomography-scan (CT-scan). From the six patients, a total of 11 adenocarcinomas (ADKs) and one squamous cell carcinoma (SCC) were analyzed. All the examined carcinomas were BRAF-wildtype microsatellite stable tumors with an epithelial histological subtype. In two of the six cases, KRAS gene status showed discordance between the two synchronous tumors, with mutations in the index tumors and wildtype status in the companion ones. Conclusions: Preoperative CT-scans can be useful for detection of synchronous tumors which may be missed by colonoscopy. Where synchronous tumors are identified, therapy should be based on the molecular profile of the indexed tumors.

Immune-checkpoint inhibitors (ICIs) play a key role in the treatment of advanced stage colorectal cancer (CRC) patients featuring a deficient DNA mismatch repair (dMMR) system or a high microsatellite instability (MSI-H) profile. However, beyond the established role in CRC patients, ICIs have highly proven efficacy in other solid tumors featuring MSI-H/dMMR status represented by endometrial, gastric, ovarian, prostatic, and pancreatic carcinomas (EC, GC, OC, PrC, and PaC). Our aim was to compare the concordance rates among the Idylla™ MSI test, TapeStation 4200, and immunohistochemical (IHC) analysis in assessing MSI-H/dMMR status in EC, GC, OC, PrC, and PaC patients. The Sanger sequencing-based Titano MSI test was used in discordant cases. One hundred and eighty-five cases (n = 40 PrC, n = 39 GC, n = 38 OC, n = 35 PaC, and n = 33 EC) were retrospectively selected. MMR protein expression was evaluated by IHC. After DNA quality and quantity evaluations, the IdyllaTM and TapeStation 4200 platforms were adopted for the evaluation of MSI status. Remarkably, compared to IHC, the Idylla™ platform achieved a global concordance rate of 94.5% (154/163) for the microsatellite stable (MSS)/proficient MMR (pMMR) cases and 77.3% (17/22) for the MSI-H/dMMR cases. Similarly, a global concordance rate of 91.4% (149/163) and 68.2% (15/22) for MSS/pMMR and MSI-H/dMMR cases was also identified between IHC and the TapeStation 4200 microfluidic system. In addition, a global concordance of 93.1% (148/159) and 69.2% (18/26) for MSS/pMMR and MSI-H/dMMR cases was observed between the Idylla™ and TapeStation 4200 platforms. Discordant cases were analyzed using the Titano MSI kit. Overall, our data pinpointed a central role for molecular techniques in the diagnostic evaluation of dMMR/MSI-H status not only in CRC patients but also in other types of solid tumors.

Background Microsatellite stable (MSS) or mismatch repair proficient (pMMR) metastatic colorectal cancer (mCRC) is resistant to immune checkpoint inhibitors. However, a recent Japanese trial showed that regorafenib plus nivolumab had encouraging anti-cancer activity in MSS or pMMR mCRCs. Materials and methods We retrospectively reviewed the efficacy and safety data of combination therapy with regorafenib plus anti-PD-1 antibody in patients with refractory MSS or pMMR mCRC in the medical centers of Shandong Province in China. Results Twenty-three patients with MSS or pMMR mCRC received regorafenib plus anti-PD-1 antibody. Eighteen (78.3%) patients experienced stable disease as best response, five (21.7%) patients had progressive disease, and no partial response was observed. The disease control rate (DCR) was 78.3% (18/23), and the median progression-free survival (PFS) was 3.1 months (95% CI, 2.32-3.89). Four of five (80.0%) patients with progressive disease had baseline liver metastasis, while nine of 18 (50.0%) patients with stable disease displayed no liver metastasis. One patient receiving radiofrequency ablation treatment for liver and abdominal wall metastases prior to combination treatment experienced a remarkably prolonged PFS of 9.2 months with SD. Neither liver metastasis status nor previous exposure to regorafenib was associated with treatment outcome. Treatment-related grade 3 toxicities were observed in 5/23 (21.7%) patients. Conclusion No objective response was observed with the combination of regorafenib plus anti-PD-1 antibody, suggesting its little clinical activity in unselected Chinese patients with pMMR/MSS mCRC. Meanwhile, it exhibited some potential benefit in this cohort in terms of DCR and PFS. Adverse events were generally tolerable and manageable. Prospective studies with large sample sizes are needed to verify the findings. This combination strategy plus local ablative therapy might be worthy of further exploration.

Immune checkpoint inhibition (ICI) has transformed the management of metastatic colorectal cancer (mCRC) with mismatch-repair deficiency (dMMR) and microsatellite instability (MSI-H), though this constitutes on average less than 5% of mCRC, and ICI is ineffective in preserved MMR/microsatellite stable disease (pMMR/MSS). Here we review the efficacy of ICI in dMMR/MSI-H mCRC, poor response to ICI in pMMR/MSS mCRC, role for ICI in locally advanced disease, biomarkers of response, novel immunotherapies, and future directions in targeting resistance mechanisms.

Purpose: Colorectal cancer (CRC) incidence is increasing in adults younger than 50 years. This study evaluated clinicopathological characteristics and outcome of adolescent and young adult (AYA)-on...

Most colorectal cancers are microsatellite-stable with no response to anti-PD-1 therapy, necessitating the development of new immunomodulatory treatment strategies. Coinhibition of anti-PD-1 and STAT3 can elicit an effective antitumor response in a small subset of patients with microsatellite-stable colorectal cancer, and biomarkers predictive of response are under investigation. See related article by Kawazoe et al., p. 5887

Background: Microsatellite-stable (MSS) colon adenocarcinoma (COAD) patients are not sensitive to immune checkpoint inhibitors. Here, we focused on analyzing the relationship between homologous recombination repair (HRR)-related gene mutations and clinical immunotherapy responses in MSS COAD. Methods: The mutational landscape was profiled in a cohort of 406 Chinese COAD patients via next-generation sequencing (NGS). Correlations between HRR gene mutations and tumor immunity or clinical outcomes in two COAD genomic datasets were analyzed via bioinformatics. Results: In the Chinese cohort, seventy (17%) patients exhibited genomic alterations in HRR genes; ATM (9%), BRCA2 (4%), ATR (3%), RAD50 (3%) and BRIP1 (3%) were the most frequently mutated. In the MSK-IMPACT COAD cohort (immune checkpoint inhibitor-treated), HRR-mut patients (n=34) survived longer than HRR-wt patients (n=50) (log-rank P < 0.01). Based on the TCGA MSS COAD cohort, HRR gene mutations increased immune activities, such as infiltration of cytotoxic cells (P < 0.05) and exhausted CD8+ T cells (P < 0.01), and increased the IFN-γ scores (P < 0.05). The results differed in MSI-H COAD patients (all P > 0.05). Conclusion: HRR gene mutations significantly increased immune activities in MSS COAD patients, implying the feasibility of the HRR-mut status as an immunotherapy response predictor in MSS COAD.

Key Points Question Can combined immune checkpoint inhibition improve overall survival (OS) in patients with advanced refractory colorectal cancer (CRC)? Findings In this randomized phase 2 study with 180 patients randomized in a 2:1 ratio to tremelimumab and durvalumab plus best supportive care or best supportive care alone, the median OS was 6.6 months for durvalumab and tremelimumab and 4.1 months for best supportive care; correlative analysis revealed that patients with plasma tumor mutation burden (TMB) of 28 or more variants per megabase had the greatest OS benefit. Meaning Combined immune checkpoint inhibition may prolong OS in patients with advanced refractory CRC., This phase 2 randomized clinical trial evaluates the outcomes of combined immune checkpoint inhibition plus best supportive care vs best supportive care alone for patients with advanced colorectal cancer., Importance Single-agent immune checkpoint inhibition has not shown activities in advanced refractory colorectal cancer (CRC), other than in those patients who are microsatellite-instability high (MSI-H). Objective To evaluate whether combining programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte–associated protein 4 (CTLA-4) inhibition improved patient survival in metastatic refractory CRC. Design, Setting, and Participants A randomized phase 2 study was conducted in 27 cancer centers across Canada between August 2016 and June 2017, and data were analyzed on October 18, 2018. Eligible patients had histologically confirmed adenocarcinoma of the colon or rectum; received all available standard systemic therapies (fluoropyrimidines, oxaliplatin, irinotecan, and bevacizumab if appropriate; cetuximab or panitumumab if RAS wild-type tumors; regorafenib if available); were aged 18 years or older; had adequate organ function; had Eastern Cooperative Oncology Group performance status of 0 or 1, and measurable disease. Interventions We randomly assigned patients to receive either 75 mg of tremelimumab every 28 days for the first 4 cycles plus 1500 mg durvalumab every 28 days, or best supportive care alone (BSC) in a 2:1 ratio. Main Outcomes and Measures The primary end point was overall survival (OS) and a 2-sided P

In an integrated genomic and clinical analysis, we evaluate the effects of Wnt and DNA damage response pathway alterations on metastatic colorectal cancer.

BackgroundColon cancer (CRC) is the second leading cause of cancer-related deaths in the US. CRC incidence is on the rise and there is an alarming increase in young onset CRC cases. Immune checkpoint inhibitors (ICIs) have yielded promising anti-tumor results in microsatellite instable high (MSI-high) patients, which represent only 15% of tumors. The remaining 85% are denoted as microsatellite stable (MSS) and are unresponsive to ICI. Using a murine glioma model, our group has previously found the combination of anti-PD-1 and a transfer of hematopoietic stem cells (HSCs) can sensitize mice that are resistant to anti-PD-1 alone. We evaluated survival after treatment with this combinatorial platform 3 or 5 days post-implantation in subcutaneous CRC-bearing mice and also phenotyped the splenic compartment of mice at endpoint.Methods1x106 MSS CRC cells, CT26, were subcutaneously injected into the right flank of BALB/cJ mice. 3 or 5 days later, HSCs were isolated from naïve BALB/cJ mice and injected through the tail vein into CT26-bearing mice and were also given 10 mg/kg anti-PD-1. Mice were given 3 additional doses of anti-PD-1 for a total of doses either every 3 or 5 days. Mice were sacrificed when tumors reached 1.5 cm at its widest point and spleens were excised and stained for flow cytometry.ResultsWhen mice were treated with HSC/anti-PD-1 3 days post-tumor implantation, we observed a statistically significant increase in survival in mice that received combinatorial HSCs and anti-PD-1 relative to no treatment control mice (p=0.0034, Mantel-Cox long-rank test) as well as mice that received HSCs alone (p=0.0462, Mantel-Cox log-rank test. In the same 3 day cohort, no differences in the frequency of T cell populations were observed. However, we found mice that received this combination therapy had a significant increase in the frequency of splenic CD11c+ MHC II+ dendritic cells (DCs) relative to no treatment control mice (p=0.0364, Mann-Whitney t test). When mice were treated with HSC/anti-PD-1 5 days post-tumor implantation, we found a statistically significant increase in survival of mice treated with combinatorial HSCs and anti-PD-1 compared to no treatment control mice (p=0.0024, Mantel-Cox log-rank test) and relative to mice that received HSC monotherapy (p=0.0462, Mantel-Cox log-rank test).ConclusionsThese results suggest combinatorial HSCs and anti-PD-1 represents a promising therapeutic axis in a murine model of MSS CRC. In addition, the increase in splenic DCs suggests the mechanism behind this anti-tumor response may be expansion of DCs within the periphery.Ethics ApprovalAll animal work approved through University of Florida IACUC # 201910777

Approximately 20% early-stage (I/II) colorectal cancer (CRC) patients develop metastases despite curative surgery. We aim to develop a formalin-fixed and paraffin-embedded (FFPE)-based predictor of metastases in early-stage, clinically-defined low risk, microsatellite-stable (MSS) CRC patients. We considered genome-wide mRNA and miRNA expression and mutation status of 20 genes assayed in 150 fresh-frozen tumours with known metastasis status. We selected 193 genes for further analysis using NanoString nCounter arrays on corresponding FFPE tumours. Neither mutation status nor miRNA expression improved the estimated prediction. The final predictor, ColoMet19, based on the top 19 genes' mRNA levels trained by Random Forest machine-learning strategy, had an estimated positive-predictive-value (PPV) of 0.66. We tested ColoMet19 on an independent test-set of 131 tumours and obtained a population-adjusted PPV of 0.67 indicating that early-stage CRC patients who tested positive have a 67% risk of developing metastases, substantially higher than the metastasis risk of 40% for node-positive (Stage III) patients who are generally treated with chemotherapy. Predicted-positive patients also had poorer metastasis-free survival (hazard ratios [HR] = 1.92, design-set; HR = 2.05, test-set). Thus, early-stage CRC patients who test positive may be considered for adjuvant therapy after surgery.

ZusammenfassungEine Meningeosis neoplastica ist eine seltene, aber schwerwiegende Komplikation solider Neopasien (Melanome, Mamma-, Bronchial- oder gastrointestinale Karzinome). Die klinische Manifestation der Meningeosis ist äußerst variabel. Sie äußert sich z. B. in radikulären Schmerzen mit oder ohne neurologischen Ausfällen sowie in Kopfschmerzen bis hin zu halluzinatorischen Reizsymptomen. Ob dieses unspezifischen Symptomcharakters wird eine Meningeosis neoplastica häufig zu spät diagnostiziert und behandelt. Wir berichten hier über den seltenen Fall einer Patientin mit einem lymphatisch und ossär metastasierten BRAF-mutierten Mikrosatelliten-stabilen Kolonkarzinom, welche einen Monat nach der Diagnosestellung neurologische Reiz- und Ausfallsymptome entwickelte. Durch den zytologischen Nachweis von Tumorzellen im Liquorsediment konnte – trotz einer unauffälligen MRT-Diagnostik – eine Meningeosis carcinomatosa gesichert werden. Unter einer intrathekalen Therapie mit Methotrexat, kombiniert mit einer intensiven systemischen Antikörperchemotherapie, wurde passager eine gute partielle Remission der Tumorerkrankung erreicht. Ca. 8 Monate nach Therapiebeginn entwickelte jedoch die Patientin eine progrediente Meningeosis und verstarb wenige Wochen später.

The introduction of checkpoint inhibitors provided remarkable achievements in several solid tumors but only 5% of metastatic colorectal cancer (mCRC) patients, i.e., those with bearing microsatellite instable (MSI-high)/deficient DNA mismatch repair (dMMR) tumors, benefit from this approach. The favorable effect of immunotherapy in these patients has been postulated to be due to an increase in neoantigens due to their higher somatic mutational load, also associated with an abundant infiltration of immune cells in tumor microenvironment (TME). While in patients with dMMR tumors checkpoint inhibitors allow achieving durable response with dramatic survival improvement, current results in patients with microsatellite stable (MSS or MSI-low)/proficient DNA mismatch repair (pMMR) tumors are disappointing. These tumors show low mutational load and absence of “immune-competent” TME, and are intrinsically resistant to immune checkpoint inhibitors. Modifying the interplay among cancer cells, TME and host immune system is the aim of multiple lines of research in order to enhance the immunogenicity of pMMR mCRC, and exploit immunotherapy also in this field. Here, we focus on the rationale behind ongoing clinical trials aiming at extending the efficacy of immunotherapy beyond the MSI-high/dMMR subgroup with particular regard to academic no-profit studies.

Background: Grade 3 (G3, poorly differentiated) is an important treatment-decision factor in stage II colon cancer, but no unified diagnostic criteria are established. According to previous studies, an intra-tumoural poorly differentiated area with no glandular formation (POR) that fills the microscopic field of a 40× objective lens was an essential factor that defined G3. We aimed to prospectively validate this in a randomised controlled study of adjuvant chemotherapy (SACURA trial). Methods: Between 2006 and 2010, we enrolled 991 patients with stage II colon cancer from 123 institutions. POR was quantitatively graded according to the 40× objective lens rule and the intensity of poorly differentiated clusters (GradePOR). The prognostic power of GradePOR was compared with that of the conventional tumour grade based on the predominant histology rule (Gradeconv). Findings: According to GradePOR, 313, 526 and 152 tumours were classified as G1POR, G2POR and G3POR, respectively, and the 5-year relapse-free survival (RFS) rates were 91·1%, 82·9%, and 74·7%, respectively (P < 0·0001). When G3POR and G3conv were alternatively added to the standard prognostic model consisting of eight conventional factors, only G3POR was a significant factor for RFS (P = 0·040, Wald test). The adverse impact of G3POR on RFS was greater in the microsatellite stable (MSS)/microsatellite instability (MSI)-low subset (hazard ratio [HR], 2·61; 95% confidence interval [CI], 1·81–3·77) compared with that in the full analysis set (HR, 1·93; 95% CI, 1·34–2·77). In the MSS/MSI-low subset, the 5-year RFS rate of patients with G3POR tumours in the adjuvant chemotherapy group achieved greater improvement (9·1%) than the surgery-alone group (HR, 0·65; 95% CI, 0·34–1·24). Interpretation: The validated prognostic value of the least differentiation policy with the 40× objective lens rule may be highlighted as the diagnostic criterion for G3 in the adjuvant treatment setting for stage II colon cancer, particularly for MSS/MSI-low tumours. Trial Registration: ClinicalTrials.gov NCT00392899 Funding: This study was supported by the Foundation for Biomedical Research and Innovation at Kobe, Translational Research Center for Medical Innovation (TRI), under the funding contract with Taiho Pharmaceutical Co. Ltd., Japan. Declaration of Interests: MI has received consulting fees from Taiho Pharmaceutical Co. Ltd., BristolMyers Squibb and Merck Serono Co. Ltd; honoraria from Taiho, Chugai Pharmaceutical Co. Ltd., and Yakult Honsha Co. Ltd. HM has received consulting fees from Otsuka Pharmaceutical Factory, Inc. and Sysmex Co.; honoraria from Taiho, Chugai, Yakult Honsha, Daiichi Sankyo Co. Ltd., Astellas Pharma Inc. NT has received research funding from Taiho, Chugai, and Yakult Honsha; honoraria from Taiho, Chugai, Takeda Pharmaceutical Co. Ltd., Merck Serono. YS has received honoraria from Taiho, Chugai and Yakult Honsha. KT has received honoraria from Taiho and Takeda. KK has received consulting fees from Taiho and Chugai; honoraria from Taiho, Chugai, Bristol-Myers, Merck Serono and Otsuka. MW has received research funding from Taiho, Chugai, Yakult Honsha, Johnson and Johnson K. K. and Covidien Japan Co. Ltd. YK has received honoraria from Taiho and Chugai. H. Ueno has received honoraria from Taiho, Chugai, Yakult Honsha, BristolMyers and Daiichi Sankyo. TI has received research funding from Taiho; honoraria from Chugai. H. Uetake has received consulting fees, research funding, and honoraria from Taiho, Chugai, Takeda, Bristol-Myers and Merck Serono. SM has no competing interest. ST has received consulting fees from Taiho, Daiichi Sankyo and Solasia Pharma K. K.; research funding from Daiichi Sankyo, Yakult Honsha and Kureha Co. Ltd.; honoraria from Daiichi Sankyo. KS has received consultant fees, research funding and honoraria from Taiho, Chugai, Takeda, Yakult Honsha, Daiichi Sankyo, Bristol-Myers, Merck Serono, and Pfizer Co. Ltd. Ethics Approval Statement: The study protocol was approved by the Institutional Review Boards of each participating institution and was conducted in accordance with the tenets of the Declaration of Helsinki and comparable Japanese ethical standards. Furthermore, written informed consent was obtained from all study participants.

PURPOSE:To predict microsatellite instability (MSI) status of colon cancer on preoperative CT imaging using radiomic analysis. METHODS:This retrospective study involved radiomic analysis of preoperative CT imaging of patients who underwent resection of stage II-III colon cancer from 2004 to 2012. A radiologist blinded to MSI status manually segmented the tumor region on CT images.254 Intensity-based radiomic features were extracted from the tumor region. Three prediction models were developed with (1) only clinical features, (2) only radiomic features, and (3) "combined" clinical and radiomic features. Patients were randomly separated into training (n = 139) and test (n = 59) sets. The model was constructed from training data only; the test set was reserved for validation only. Model performance was evaluated using AUC, sensitivity, specificity, PPV, and NPV. RESULTS:Of the total 198 patients, 134 (68%) patients had microsatellite stable tumors and 64 (32%) patients had MSI tumors. The combined model performed slightly better than the other models, predicting MSI with an AUC of 0.80 for the training set and 0.79 for the test set (specificity = 96.8% and 92.5%, respectively), whereas the model with only clinical features achieved an AUC of 0.74 and the model with only radiomic features achieved an AUC of 0.76. The model with clinical features alone had the lowest specificity (70%) compared with the model with radiomic features alone (95%) and the combined model (92.5%). CONCLUSIONS:Preoperative prediction of MSI status via radiomic analysis of preoperative CT adds specificity to clinical assessment and could contribute to personalized treatment selection.

Programmed death 1 (PD-1)-targeted therapy has benefited patients with microsatellite instability-high metastatic colorectal cancer (mCRC). However, the efficacy of PD-1-targeted therapy is poor in patients with microsatellite-stable (MSS) mCRC. Therefore, it is imperative to explore additional co-inhibitory molecular signalling pathways to improve the efficacy of immunotherapy in MSS mCRC treatment. In the present study, the association between cyclin-dependent kinase 9 (CDK9) expression and the survival of patients with CRC was analysed using RNA sequencing data from 605 patients, including 121 cases of mortality, from human cancer datasets. Furthermore, 35 clinical MSS stage III–IV CRC specimens were collected to assess CDK9 protein expression by immunohistochemistry, and the frequency of tumor-infiltrating CD8+ T cells was assessed by flow cytometry. The human cancer datasets demonstrated that upregulation CDK9 significantly shortened the survival of patients with stage II–IV colon cancer. Additionally, CDK9 mRNA expression was positively correlated with the expression levels of genes associated with immune evasion in the tumor. Notably, CDK9 was expression was upregulated in stage IV CRC compared with para-cancerous tissues and early-stage tumors. Interestingly, CDK9 expression was negatively associated with the infiltration of CD8+ T cells at the tumor site. In addition, the expression levels of T-cell immunoglobulin mucin family member 3 and CD39, proteins associated with exhaustion, on tumor-infiltrating CD8+ T cells were significantly elevated in patients with abnormal CDK9 expression levels. The present study demonstrated that CDK9 expression was negatively associated with CD8+ T cell infiltration and positively associated with CD8+ T cell exhaustion in MSS mCRC. In conclusion, CDK9 may be utilized to evaluate the prognosis and the immune-type of the tumor microenvironment in patients with MSS mCRC.

Recent research has established tumor budding as a prognostic factor and a possible histomorphologic reflection of epithelial-mesenchymal transition in colorectal cancer, highlighting the ability of cancer cells exhibiting epithelial-mesenchymal transition to resist chemotherapy.This study aimed to investigate the clinical benefits of adjuvant chemotherapy according to the tumor budding status in microsatellite-stable stage III colorectal cancer.This was a retrospective study of 2 cohorts.The study was conducted at the National Defense Medical College in Japan.We reviewed 2 data sets of patients with microsatellite-stable stage III colorectal cancer with curatively intended surgery (R0) from 1999 to 2005 (first cohort; n = 203) and 2006 to 2012 (second cohort; n = 346). In both cohorts, 128 and 203 patients received 5-fluorouracil-based adjuvant chemotherapy and 75 and 143 patients did not.We assessed the benefits of adjuvant chemotherapy according to the grades of tumor budding based on the cancer-specific survival.In low-budding tumors, the chemotherapy group exhibited better cancer-specific survival than the surgery-alone group (first cohort, 93.1% vs 65.5%, p = 0.001; second cohort, 94.0% vs 76.0%, p0.0001). Conversely, the prognostic difference between the chemotherapy and surgery-alone groups was statistically insignificant in high-budding tumors (first cohort, 59.7% vs 52.4%, p = 0.57; second cohort, 83.1% vs 75.6%, p = 0.19). The multivariate analysis corroborated the benefits of adjuvant chemotherapy in low-budding tumors (first cohort, p = 0.002, HR = 0.28; second cohort, p0.0001, HR = 0.23) but not in high-budding tumors.Postoperative adjuvant chemotherapy and treatments for recurrence were not homogeneous, and the patient backgrounds differed between the chemotherapy and surgery alone groups.The high-budding group demonstrated resistance to 5-fluorouracil-based chemotherapy, whereas the low-budding group exhibited significant survival benefits from adjuvant chemotherapy in stage III colorectal cancer. See Video Abstract at http://links.lww.com/DCR/B14. BENEFICIOS DE SUPERVIVENCIA DIFERENCIAL DE LA QUIMIOTERAPIA ADYUVANTE BASADA EN 5-FLUOROURACILO PARA PACIENTES CON CÁNCER COLORRECTAL EN ESTADIO III ESTABLE CON MICROSATÉLITE SEGÚN EL ESTADO DE BROTACIÓN DEL TUMOR: UN ANÁLISIS RETROSPECTIVO:: Investigaciones recientes han establecido la aparición de tumores como un factor pronóstico y una posible reflexión histomorfológica de la transición epitelial-mesenquimatosa en el cáncer colorrectal, destacando la capacidad de las células cancerosas que presentan una transición epitelio-mesenquimática para resistir la quimioterapia.El objetivo de este estudio es investigar los beneficios clínicos de la quimioterapia adyuvante según el estado de brotación del tumor en el cáncer colorrectal en estadio III estable con microsatélite.Este fue un estudio retrospectivo de dos cohortes.El estudio se realizó en la Escuela de Medicina de la Defensa Nacional de Japón.Revisamos dos conjuntos de datos de pacientes con cáncer colorrectal en estadio III estable con microsatélite con cirugía de intención curativa (R0) de 1999 a 2005 (primera cohorte; n = 203) y 2006 a 2012 (segunda cohorte; n = 346). En ambas cohortes, 128 y 203 pacientes recibieron quimioterapia adyuvante basada en 5-fluorouracilo y 75 y 143 pacientes no, respectivamente.Evaluamos los beneficios de la quimioterapia adyuvante de acuerdo con los grados de brotación del tumor en función de la supervivencia específica del cáncer.n los tumores con brotes bajos, el grupo de quimioterapia mostró una mejor supervivencia específica al cáncer que el grupo con cirugía sola (primera cohorte, 93.1% vs. 65.5%, p = 0.001; segunda cohorte, 94.0% vs. 76.0%, p0.0001). A la inversa, la diferencia pronóstica entre los grupos de quimioterapia y cirugía sola fue estadísticamente insignificante en los tumores de brotes elevados (primera cohorte, 59.7% vs. 52.4%, p = 0.57; segunda cohorte, 83.1% vs. 75.6%, p = 0.19). El análisis multivariado corroboró los beneficios de la quimioterapia adyuvante en los tumores de brotes bajos (primera cohorte, p = 0,002, índice de riesgo: 0,28; segundo cohorte, p0,0001, índice de riesgo: 0,23) pero no en los tumores de alto brote.a quimioterapia adyuvante postoperatoria y los tratamientos para la recurrencia no fueron homogéneos, y los antecedentes de los pacientes difirieron entre los grupos de quimioterapia y cirugía sola.El grupo de alto brote demostró resistencia a la quimioterapia basada en 5-fluorouracilo, mientras que el grupo de bajo brote mostró beneficios significativos de supervivencia de la quimioterapia adyuvante en el cáncer colorrectal en estadio III. Vea el Resumen del Video en http://links.lww.com/DCR/B14.

Immunotherapy using checkpoint inhibitor targeting PD-1 and PD-L1 revolutionized the treatment of microsatellite instable metastatic colon cancer. Such treatment is now a standard of care for these patients. However, when used as monotherapy checkpoint inhibitors targeting PD-1 and PD-L1 are not effective in metastatic colorectal cancer patients with microsatellite stable tumors. Recent advances in biology provide a rationale for this intrinsic resistance and support the evaluation of combination therapy to reverse resistance. This article will highlight recent findings on the mechanism of intrinsic resistance and recent advances in clinical trials for combination therapy.

3584 Background: Patients (pts) with microsatellite stable (MSS) metastatic colorectal cancer (mCRC) that progressed on ≥2 prior therapies have limited treatment options, with median OS ranging from 6-9 months (mo). In the dose-escalation phase of this first-in-human multicohort study (NCT02720068), the anti-lymphocyte activation gene (LAG)-3 antibody favezelimab (fave) was well tolerated alone and with pembrolizumab (pembro) across all dose levels (Lakhani, SITC, 2018, abstract O26). Here, we evaluate the safety and efficacy of fave alone or in combination with pembro in pts with advanced MSS CRC from the dose confirmation phase. Methods: Eligible pts with MSS PD-1/PD-L1-treatment-naïve mCRC that progressed on prior standard-of-care (3L+) were enrolled (cohort A) to receive the RP2D of 800 mg fave alone (Arm 1), 800 mg fave + 200 mg pembro (Arm 2C), or 800 mg fave + 200 mg pembro (MK-4280A) co-formulation (Arm 5), all Q3W. Treatment continued for 35 cycles or until progression, unacceptable toxicity, or investigator/pt decision. Pts with confirmed progression per irRECIST v1.1 on fave alone could crossover to 800 mg fave + pembro. Safety was assessed in all treated pts; efficacy in the full analysis set (FAS) of all treated pts with baseline scan. Objectives included safety (primary), ORR (RECIST v1.1 by investigator [secondary]), and DOR, PFS, and OS (exploratory). Interim analysis data cut-off was: Oct. 23, 2020. Results: A total of 20 pts received fave (Arm 1); 89 pts (including 9 crossover) received fave + pembro (Arms 2C+5); 12 pts (Arm 1) and 36 pts (Arms 2C+5), had PD-L1 CPS ≥1 tumors. At data cut-off, median follow-up was 5.8 months (mo) in Arm 1 and 6.2 mo in Arms 2C+5. Treatment-related adverse events (TRAEs) were 65% with fave (Arm 1) and 65.2% with fave + pembro (Arms 2C+5). Grade ≥3 TRAEs were 15% (Arm 1), and 20% [Arms 2C+5]). No grade 5 TRAEs were reported. Common TRAEs (≥15%) included fatigue (20.0%), nausea (15%) with fave, and fatigue (16.9%) with fave + pembro. Confirmed ORR was 6.3% (4PR, 1CR) with fave + pembro (Arms 2C+5). No pt receiving fave alone responded. In Arms 2C+5, median DOR was 10.6 mo (range, 5.6-12.7). ORR, OS and PFS by PD-L1 status are reported in the Table. Conclusions: Favezelimab alone or in combination with pembrolizumab had a manageable safety profile, with no treatment-related deaths. Promising antitumor activity was observed with combination therapy, including with MK-4280A, compared with monotherapy most notably in pts with PD-L1 CPS ≥1 tumors. Clinical trial information: NCT02720068. [Table: see text]