Clinicopathologic profile, immunophenotype, and genotype of CD274 (PD-L1)-positive colorectal carcinomas

Immunohistochemical expression of PD-L1 in colorectal carcinoma among black patients and the clinicopathological correlates: a cross-sectional study

BACKGROUND

Colorectal cancer (CRC) incidence is rising in Nigeria, with majority of patients presenting with advanced disease. Despite promising results of PD-L1 antibody therapy in clinical trials, efficacy data exclusively derives from Caucasian populations, leaving a critical knowledge gap for African populations. This study investigated PD-L1 expression in CRC among blacks, correlating it with clinicopathologic parameters.

METHODS

The immunohistochemical expression of PD-L1 was evaluated in 96 cases of CRC diagnosed between February 2022 and January 2024, using formalin-fixed paraffin-embedded (FFPE) tissue blocks. Statistical analysis was performed using SPSS version 25. The relationships between the PD-L1 expression and the clinicopathological parameters of CRC patients were determined using the chi-square test and Spearman's rank correlation. p < 0.05 was considered to be statistically significant.

RESULTS

CRC showed a male: female ratio of 1:1.8, most occurred in the seventh decade and 54.17% were right-sided. Adenocarcinoma NOS accounted for 72.5%. The majority (n = 55, 57.3%) of the patients were diagnosed at an advanced stage. PD-L1 expression was observed in 86.46% of cases, significantly correlating with tumour Size (r = 0.263, p = 0.010*), histologic Grade (r = 0.446, p = 0.000*) and tumour Stage (r = 0.367, p = 0.000*).

CONCLUSION

This study highlighted the high frequency of PD-L1 expression in CRC among black patients, with significant associations to clinicopathologic parameters. The findings suggest the potential benefit of PD-1/PD-L1 targeted therapies and emphasize the need for enhanced early detection and screening in Nigeria.

Whole-Genome Sequencing Reveals Individual and Cohort Level Insights into Chromosome 9p Syndromes

Previous genomic efforts on chromosome 9p deletion and duplication syndromes have utilized low resolution strategies (i.e., karyotypes, chromosome microarrays). We present the first large-scale whole-genome sequencing (WGS) study of 100 individuals from families with 9p-related syndromes including 85 unrelated probands through the 9P-ARCH (Advanced Research in Chromosomal Health: Genomic, Phenotypic, and Functional Aspects of 9p-Related syndromes) research network. We analyzed the genomic architecture of these syndromes, highlighting fundamental features and their commonalities and differences across individuals. This work includes a machine-learning model that predicts 9p deletion syndrome from gene copy number estimates using WGS data. Two Late Replicating Regions (LRR1 [a previously un-named human fragile site], LRR2) were identified that contain most structural variant breakpoints in 9p deletion syndrome pointing to replication-based issues in structural variant formation. Furthermore, we show the utility of using WGS information to obtain a comprehensive understanding of 9p-related variation in an individual with complex structural variation where chromothripsis is the likely mechanism. Genes on 9p were prioritized based on statistical assessment of human genomic variation. Furthermore, through application of spatial transcriptomics to embryonic mouse tissue we examined 9p-gene expression in craniofacial and brain development. Through these strategies, we identified 24 important genes for the majority (83%) of individuals with 9p deletion syndrome including AK3, BRD10, CD274, CDC37L1, DMRT1, DMRT2, DMRT3, DOCK8, GLIS3, JAK2, KANK1, KDM4C, PLPP6, PTPRD, PUM3, RANBP6, RCL1, RFX3, RIC1, SLC1A1, SMARCA2, UHRF2, VLDLR, and ZNG1A. Two genes (AK3, ZNG1A) are involved in mitochondrial function and testing of the mitochondrial genome revealed excess copy number in individuals with 9p deletion syndrome. This study presents the most comprehensive genomic analysis of 9p-related syndromes to date, with plans for further expansion through our 9P-ARCH research network.

A Narrative Review of the Role of Immunotherapy in Metastatic Carcinoma of the Colon Harboring a BRAF Mutation

Patients affected by metastatic carcinoma of the colon/rectum (mCRC) harboring mutations in the BRAF gene (MBRAF) respond poorly to conventional therapy and have a prognosis worse than that of patients without mutations. Despite the promising outcomes of targeted therapy utilizing multi-targeted inhibition of the mitogen-activated protein kinase (MAPK) signaling system, the therapeutic efficacy, especially for the microsatellite stable/DNA proficient mismatch repair (MSS/PMMR) subtype, remains inadequate. Patients with MBRAF/mCRC and high microsatellite instability or DNA deficient mismatch repair (MSI-H/DMMR) exhibit a substantial tumor mutation burden, suggesting a high probability of response to immunotherapy. It is widely acknowledged that MSS/pMMR/mCRC is an immunologically "cold" malignancy that exhibits resistance to immunotherapy. The integration of targeted therapy and immunotherapy may enhance clinical outcomes in patients with MBRAF/mCRC. Efforts to enhance outcomes are exclusively focused on MSS/DMMR-BRAF mutant cancers, which constitute the largest proportion. This review evaluates the clinical efficacy and advancement of novel immune checkpoint blockade therapies for MSI-H/DMMR and MSS/PMMR BRAF mutant mCRC. We examine potential indicators in the tumor immune milieu for forecasting immunotherapeutic response in BRAF mutant mCRC.

Impact of Kiwifruit Consumption on Cholesterol Metabolism in Rat Liver: A Gene Expression Analysis in Induced Hypercholesterolemia

BACKGROUND/OBJECTIVES

Cholesterol is vital in various bodily functions, such as maintaining cell membranes, producing hormones, etc. However, imbalances, like hypercholesterolemia, can lead to diseases such as cancer, kidney disease, non-alcoholic fatty liver disease, and cardiovascular conditions. This study explores the impact of kiwifruit consumption, specifically Actinidia arguta cultivar Geneva and Actinidia deliciosa cultivar Hayward, on cholesterol and lipid metabolism in rat liver.

METHODS

Rats were divided into groups: a 1% cholesterol control group (Ch), a 5% Geneva kiwifruit-supplemented group (ChGENE), and a 5% Hayward kiwifruit-supplemented group (ChHAYW). Gene expression was analyzed using Gene Spring v.14. Gene ontology, pathway analysis, miRNA, and transcription factor prediction were performed using DAVID, Reactome, and miRNet. In addition, we used Agilent Literature Search software to gain further insights.

RESULTS

Statistical analysis identified 72 genes in ChGENE-Ch and 2 genes in ChHAYW-Ch comparison. Key genes involved in cholesterol metabolism pathways, including PCSK9, SCD1, SLC27A5, HMGCR, and DHCR24, showed lower expression in the kiwifruit-supplemented groups. The genes mentioned above showed lower expression in the kiwifruit-supplemented group, probably contributing to the liver lipid level reduction. Further analysis identified miRNA-26a, miRNA-29a/b/c, miRNA-33a/b, and miRNA-155 targeting hub genes.

CONCLUSIONS

Our findings suggest that dietary supplementation with kiwifruit, particularly the Geneva cultivar, reduces fat accumulation in the liver of rats with hypercholesterolemia, likely through downregulation of critical genes involved in cholesterol metabolism. These studies highlight the potential of kiwifruit as a part of a dietary strategy to manage cholesterol levels.

Immunohistochemistry Expression of Programmed Death-Ligand 1 in Colorectal Carcinoma among Nigerians

BACKGROUND

Colorectal carcinoma (CRC) is the most common gastrointestinal malignancy in Nigeria with a dismal 5-year survival rate. Interactions between the CD8+ T-lymphocytes and the immune checkpoints such as cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed death-ligand 1 (PD-L1) expressions are important. Novel antibodies have been developed against these immune checkpoints and have been found to improve clinical outcome in many solid organ malignancies.

AIM

We aimed to determine immunohistochemical expression of PD-L1 in resected CRC cases assembled on tissue microarray blocks.

METHODS

Representative blocks and clinical information of resected CRC cases between 2010 and 2019 were retrieved from the archives of our department. Tissue microarray (6 × 4) blocks were constructed with 2 mm core needles. Immunohistochemistry using anti-PD-L1 rabbit monoclonal antibody (clone EPR19759 #213524, 1:200 Abcam, MA, USA) was carried out according to manufacturer's instruction.

RESULTS

The study included 170 cases, of which 144 cases had sufficient tissue for analysis. The peak incidence was observed in the 50-59 age group. Approximately 80.1% of the cases were in T3 and T4 stages. Only 8 (5.6%) out of 144 cases were positive for PD-L1. All the PD-L1 positive cases were either right-sided CRC (6/68) or rectal cancer (2/3). Of the seven positive cases with available histological grading, four were poorly differentiated/mucinous variants and three cases were moderately differentiated.

CONCLUSION

PD-L1 expression in CRC was low (5.6%) and showed strong associations with higher tumor grades (P < 0.013), right-sided tumors (P < 0.002), and rectal cancer. There was no association with age, tumor stage, and lymph node status.

A Comprehensive Study on the Prognostic Value and Clinicopathological Significance of Different Immune Checkpoints in Patients With Colorectal Cancer: A Systematic Review and Meta-Analysis

Background

The prognostic significance of immune checkpoint expression in the tumor microenvironment has been widely investigated in colorectal cancers. However, the results of these studies are inconsistent and limited to some immune checkpoints.

Objective

The study aimed to investigate the correlation between different immune checkpoint expression and clinicopathological features and prognostic parameters.

Methods

We conducted a systematic review and meta-analysis of the published literature in PubMed, Web of Science-Core Collection, Scopus, Embase, and Cochrane databases to summarize the association between various immune checkpoints expression on both tumor cells and immune cells with clinicopathological features and prognostic parameters in patients with colorectal cancer.

Results

One hundred four studies incorporating 22,939 patients were included in our meta-analysis. Our results showed that among the B7 family, the high expression of B7H3, B7H4, PD-1, and PD-L1 on tumor cells and tumor tissue was significantly associated with higher T stage, advanced tumor, node, metastasis (TNM) stage, presence of vascular invasion, and lymphatic invasion. In addition, patients with high expression of B7H3, B7H4, PD-1, PD-L1, and PD-L2 were associated with shorter overall survival. High expression of PD-1 and PD-L1 in immune cells correlated with the absence of lymph node metastasis, lower TNM stage, early T stage, poor overall survival, and disease-free survival, respectively. Moreover, we found significant positive correlations between CD70 and Galectin-3 expression with advanced T stage. HLA-II overexpression was correlated with the absence of lymph node metastasis (odds ratio = 0.21, 95% CI = 0.11-0.38, P < 0.001) and early TNM stage (odds ratio = 0.35, 95% CI = 0.26-0.47, P < 0.001).

Conclusions

Overexpression of B7H3, B7H4, PD-1, PD-L1, PD-L2, CD70, and Galectin-3 on tumors is significantly associated with unfavorable clinicopathological characteristics and poor prognostic factors. Hence, these immune checkpoints can serve as predictive biomarkers for prognosis and the clinicopathological features of colorectal cancer because this is essential to identify patients suitable for anticancer therapy with immune checkpoint inhibitors.

Use of SATB2 and CDX2 Immunohistochemistry to Characterize and Diagnose Colorectal Cancer

SATB2 has been reported to be highly specific for lower gastrointestinal tract tumors. On the basis of its ileum-colon conversion effects, which involve the activation of colonic genes in cooperation with CDX2 and HNF4A, we hypothesized that SATB2 and CDX2 might define the characteristics of colorectal cancers (CRCs). In the present study, the clinicopathologic and immunohistochemical characteristics of 269 CRCs were analyzed according to SATB2 and CDX2 expression. CRCs with SATB2- and/or CDX2- phenotypes showed associations with poorly differentiated histotypes ( P <0.00001), mucus production ( P =0.0019), and mismatch repair-deficient phenotypes ( P <0.00001). SATB2-/CDX2- CRCs were significantly associated with CK20-negativity, with or without CK7 expression ( P <0.00001), as well as with MUC5AC-positivity ( P <0.00001), and CD10-negativity ( P =0.00047). Negativity for SATB2 or CDX2 was associated with the expression of PD-L1 in both all CRC ( P <0.00001) and mismatch repair-proficient CRC ( P =0.000091). Multivariate Cox hazard regression analysis identified negativity for SATB2 and/or CDX2 as potential independent risk factors for patients with CRC. Regarding the diagnostic utility of SATB2, all of the 44 CRC metastases could be diagnosed as colorectal in origin if the immunohistochemical phenotypes (including CK7, CK20, and p53) of the primary lesions and patient history were considered. Among the other 684 tumors, we were unable to distinguish a case of CK7-/CK20+/CDX2+/SATB2+ ovarian mucinous cystadenocarcinoma from metastatic CRC without the patient history and clinical information.

POLE -related gene signature predicts prognosis, immune feature, and drug therapy in human endometrioid carcinoma

The POLE subtype of Endometrial carcinoma (EC) is linked to a favourable prognosis in the molecular classification. We proposed to ascertain the potential connection between the POLE subtype and improved prognosis. In order to forecast the prognosis, least absolute shrinkage and selection operator (LASSO) Cox regression analysis and weighted gene co-expression network analysis (WGCNA) were employed, and a POLE-related risk signature (PRS) model was developed and validated. Single-sample gene set enrichment analysis (ssGSEA) with the "GSVA" package was employed to analyse immunity characteristics. Drug susceptibility studies were conducted to compare the half-maximal inhibitory concentration (IC50) of medicines between high- and low-risk groups. The PRS model was generated employing the LASSO Cox regression coefficients of the ELF1, MMADHC, andAL021707.6 genes. Our study demonstrated that the risk score was linked to tumour stage, grade, and survival. Furthermore, the low-risk group possessed elevated levels of gene expression connected with immunological checkpoints and HLA. Our outcomes emerged that the PRS model might have value in identifying patients with a good prognosis and in facilitating personalised treatment in the clinic.

SALL4 in gastrointestinal tract cancers: upstream and downstream regulatory mechanisms

Effective therapeutic targets and early diagnosis are major challenges in the treatment of gastrointestinal tract (GIT) cancers. SALL4 is a well-known transcription factor that is involved in organogenesis during embryonic development. Previous studies have revealed that SALL4 regulates cell proliferation, survival, and migration and maintains stem cell function in mature cells. Additionally, SALL4 overexpression is associated with tumorigenesis. Despite its characterization as a biomarker in various cancers, the role of SALL4 in GIT cancers and the underlying mechanisms are unclear. We describe the functions of SALL4 in GIT cancers and discuss its upstream/downstream genes and pathways associated with each cancer. We also consider the possibility of targeting these genes or pathways as potential therapeutic options for GIT cancers.

The Expression Patterns of Immune Checkpoint Molecules in Colorectal Cancer: An Analysis Based on Microsatellite Status

Recently, immunotherapy has arisen as a novel treatment approach for patients with colorectal cancer (CRC), but the effectiveness of immunotherapy varies in these patients. We hypothesized that immune checkpoint molecules (ICMs), which are the targets of immunotherapy, are often exhibited concomitantly. Our objective was to investigate the patterns of ICM expression in patients with CRC and the differences in ICM expression based on microsatellite instability status. The immunohistochemical expression of programmed cell death protein 1 (PD-1), programmed cell death ligand 1 (PD-L1), T cell immunoglobulin and mucin-domain containing-3 (TIM-3), and lymphocyte-activation gene 3 (LAG-3) in the tumor center and periphery was assessed in patients with non-metastatic colorectal cancer. We enrolled 83 patients with CRC: a total of 40 microsatellite-stable (MSS) and 43 microsatellite-instability-high (MSI-H) cancer patients. PD-L1 was more frequently expressed in the tumor center in the MSI-H patients with than that in the MSS patients (18 [41.9%] vs. 3 [7.5%], respectively; p < 0.001), and the same trend was observed for TIM-3 expression (30 [69.8%] vs. 19 [47.5%], respectively; p = 0.047). The concomitant expression of two or more ICMs was more frequently observed than no expression or the expression of a single molecule in both the MSS and MSI-H groups; a total of 34 (79.7%) patients with MSI-H cancer and 23 (57.5%) with MSS cancer showed ICM expression at the tumor center, whereas 34 (79.7%) patients with MSI-H cancer and 22 (55%) with MSS cancer showed expression at the tumor periphery. Patients with the genetic characteristics of MSI-H cancer showed higher expression levels of ICMs than those in patients with MSS cancer, and predominantly, two or more ICMs were concurrently expressed. Our findings highlight the potential efficacy of the dual-blockade approach in immunotherapy, particularly in patients with MSI-H CRC.

Genetic and immune landscape evolution in MMR-deficient colorectal cancer

Mismatch repair-deficient (MMRd) colorectal cancers (CRCs) have high mutation burdens, which make these tumours immunogenic and many respond to immune checkpoint inhibitors. The MMRd hypermutator phenotype may also promote intratumour heterogeneity (ITH) and cancer evolution. We applied multiregion sequencing and CD8 and programmed death ligand 1 (PD-L1) immunostaining to systematically investigate ITH and how genetic and immune landscapes coevolve. All cases had high truncal mutation burdens. Despite pervasive ITH, driver aberrations showed a clear hierarchy. Those in WNT/β-catenin, mitogen-activated protein kinase, and TGF-β receptor family genes were almost always truncal. Immune evasion (IE) drivers, such as inactivation of genes involved in antigen presentation or IFN-γ signalling, were predominantly subclonal and showed parallel evolution. These IE drivers have been implicated in immune checkpoint inhibitor resistance or sensitivity. Clonality assessments are therefore important for the development of predictive immunotherapy biomarkers in MMRd CRCs. Phylogenetic analysis identified three distinct patterns of IE driver evolution: pan-tumour evolution, subclonal evolution, and evolutionary stasis. These, but neither mutation burdens nor heterogeneity metrics, significantly correlated with T-cell densities, which were used as a surrogate marker of tumour immunogenicity. Furthermore, this revealed that genetic and T-cell infiltrates coevolve in MMRd CRCs. Low T-cell densities in the subgroup without any known IE drivers may indicate an, as yet unknown, IE mechanism. PD-L1 was expressed in the tumour microenvironment in most samples and correlated with T-cell densities. However, PD-L1 expression in cancer cells was independent of T-cell densities but strongly associated with loss of the intestinal homeobox transcription factor CDX2. This explains infrequent PD-L1 expression by cancer cells and may contribute to a higher recurrence risk of MMRd CRCs with impaired CDX2 expression. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The Predictive Value of CD3+/CD8+ Lymphocyte Infiltration and PD-L1 Expression in Colorectal Cancer

AIM

The immune system plays an important role in tumor development and treatment. In this study, we aimed to determine the relationships among the expressions of PD-L1, CD3, CD8, MMR proteins, clinicopathological features, and prognosis of CRC.

METHODS

Immunohistochemistry was used to determine the expression of PD-L1, CD3, and CD8 in 771 patients with CRC.

RESULTS

The expression of PD-L1 in TC was related to the right colon, adenocarcinoma, and dMMR, and in IC, it was related to younger CRC patients and the TNM stage. The expression of CD3 and CD8 in tumor-infiltrating lymphocytes was related to lymph node metastasis and the TNM stage. The expression of PD-L1 in TC and IC was correlated with the infiltration of CD3+ and CD8+ lymphocytes. Univariate survival analysis showed that the expression of PD-L1 in TC, IC, and dMMR was related to a better prognosis. Multivariate survival analysis showed that age, TNM stage, and dMMR were independent prognostic factors for CRC. The OS of the chemotherapy was significantly higher than that of the non-chemotherapy in III-IV TNM stage patients; CRC patients with positive PD-L1 expression in TC or IC and dMMR did not benefit from chemotherapy.

CONCLUSIONS

PD-L1 expression in TC and IC was closely related to the density of CD3 and CD8 infiltration in tumor-infiltrating lymphocytes. The expression of CD3 and CD8 in tumor-infiltrating lymphocytes and the expression of PD-L1 in IC were linked to the TNM stage of CRC patients. PD-L1 expression in TC and IC and MMR status may act as an important biomarker for guiding the postoperative treatment of III-IV TNM stage CRC patients.

Inverse relationship between Fusobacterium nucleatum amount and tumor CD274 (PD-L1) expression in colorectal carcinoma

Objectives

The CD274 (programmed cell death 1 ligand 1, PD-L1)/PDCD1 (programmed cell death 1, PD-1) immune checkpoint axis is known to regulate the antitumor immune response. Evidence also supports an immunosuppressive effect of Fusobacterium nucleatum. We hypothesised that tumor CD274 overexpression might be inversely associated with abundance of F. nucleatum in colorectal carcinoma.

Methods

We assessed tumor CD274 expression by immunohistochemistry and F. nucleatum DNA within tumor tissue by quantitative PCR in 812 cases among 4465 incident rectal and colon cancer cases that had occurred in two prospective cohort studies. Multivariable logistic regression analyses with inverse probability weighting were used to adjust for selection bias because of tissue data availability and potential confounders including microsatellite instability status, CpG island methylator phenotype, LINE-1 methylation level and KRAS, BRAF and PIK3CA mutations.

Results

Fusobacterium nucleatum DNA was detected in tumor tissue in 109 (13%) cases. Tumor CD274 expression level was inversely associated with the amount of F. nucleatum in colorectal cancer tissue (P = 0.0077). For one category-unit increase in three ordinal F. nucleatum categories (negative vs. low vs. high), multivariable-adjusted odds ratios (with 95% confidence interval) of the low, intermediate and high CD274 categories (vs. negative) were 0.78 (0.41-1.51), 0.64 (0.32-1.28) and 0.50 (0.25-0.99), respectively (P trend = 0.032).

Conclusions

Tumor CD274 expression level was inversely associated with the amount of F. nucleatum in colorectal cancer tissue, suggesting that different immunosuppressive mechanisms (i.e. PDCD1 immune checkpoint activation and tumor F. nucleatum enrichment) tend to be used by different tumor subgroups.

Immune checkpoint blockade therapy for BRAF mutant metastatic colorectal cancer: the efficacy, new strategies, and potential biomarkers

BRAF mutant metastatic colorectal cancer has long been considered a tumor with a poor prognosis and a poor response to chemotherapy. Despite the efficacy of targeted therapy with multi-targeted blockade of the mitogen-activated protein kinase (MAPK) signaling pathway has brought a glimmer of hope to this group of patients, the need to improve treatment efficacy remains unmet, especially for the microsatellite stability/DNA proficient mismatch repair (MSS/pMMR) subtype. BRAF mutant colorectal cancer patients with high microsatellite instability/DNA deficient mismatch repair (MSI-H/dMMR) have high tumor mutation burden and abundant neoantigen, who are deemed as ones that could receive expected efficacy from immunotherapy. Generally, it is believed that MSS/pMMR colorectal cancer is an immunologically "cold" tumor that is insensitive to immunotherapy. However, targeted therapy combined with immune checkpoint blockade therapy seems to bring light to BRAF mutant colorectal cancer patients. In this review, we provide an overview of clinical efficacy and evolving new strategies concerning immune checkpoint blockade therapy for both MSI-H/dMMR and MSS/pMMR BRAF mutant metastatic colorectal cancer and discuss the potential biomarkers in the tumor immune microenvironment for predicting immunotherapeutic response in BRAF mutant colorectal cancer.

CD70 and PD-L1 (CD274) co-expression predicts poor clinical outcomes in patients with pleural mesothelioma

Diffuse pleural mesothelioma (PM) is a highly aggressive tumour typically associated with short survival. Recently, the effectiveness of first-line immune checkpoint inhibitors in patients with unresectable PM was reported. CD70-CD27 signalling plays a co-stimulatory role in promoting T cell expansion and differentiation through the nuclear factor κB (NF-κB) pathway. Conversely, the PD-L1 (CD274)-PD-1 (PDCD1) pathway is crucial for the modulation of immune responses in normal conditions. Nevertheless, pathological activation of both the CD70-CD27 and PD-L1-PD-1 pathways by aberrantly expressed CD70 and PD-L1 participates in the immune evasion of tumour cells. In this study, 171 well-characterised PMs including epithelioid (n = 144), biphasic (n = 15), and sarcomatoid (n = 12) histotypes were evaluated immunohistochemically for CD70, PD-L1, and immune cell markers such as CD3, CD4, CD8, CD56, PD-1, FOXP3, CD68, and CD163. Eight percent (14/171) of mesotheliomas simultaneously expressed CD70 and PD-L1 on the tumour cell membrane. PMs co-expressing CD70 and PD-L1 contained significantly higher numbers of CD8+ (p = 0.0016), FOXP3+ (p = 0.00075), and CD163+ (p = 0.0011) immune cells within their microenvironments. Overall survival was significantly decreased in the cohort of patients with PM co-expressing CD70 and PD-L1 (p < 0.0001). In vitro experiments revealed that PD-L1 and CD70 additively enhanced the motility and invasiveness of PM cells. In contrast, PM cell proliferation was suppressed by PD-L1. PD-L1 enhanced mesenchymal phenotypes such as N-cadherin up-regulation. Collectively, these findings suggest that CD70 and PD-L1 both enhance the malignant phenotypes of PM and diminish anti-tumour immune responses. Based on our observations, combination therapy targeting these signalling pathways might be useful in patients with PM.

Medullary carcinoma of the ampulla has distinct clinicopathologic characteristics including common association with microsatellite instability and PD-L1 expression

Medullary carcinomas have not yet been fully characterized in the ampulla. Here, 359 ampullary carcinomas (ACs) were reviewed and 11 medullary-type carcinomas (3%) were found and analyzed. In addition to the diagnostic medullary pattern, 6 showed focal mucinous and 8 had focal abortive gland-like formations. They occurred in younger patients (57 versus 65 y; P = .02), had larger invasion size (mean, 3.2 versus 1.9 cm; P = .01), formed nodular polypoid or plaque-like tumors, and often lacked preinvasive component. In addition to the lymphoplasmacytic infiltrates, they also had prominent eosinophils in 5 of 11 cases. Eight were papilla Vateri-NOS (not otherwise specified) tumors, 2 were ampullary-duodenal origin, 1 had a minor intra-ampullary papillary tubular neoplasm component, and none were ampullary-ductal. Although they had pushing-border infiltration, perineural and vascular invasion was common. They were strongly associated with DNA mismatch repair (MMR) protein deficient (7/11, 64%). The 5-yr survival rate (53%) appeared to be comparable with, and perhaps even better than that of nonmedullary ACs (47%), although this did not reach statistical significance (P = .47). Programmed cell death ligand-1 (PD-L1) expression levels were assessed in 8, and all 4 that were MMR deficient were positive both by combined positive score (CPS) ≥1 and tumor proportion score (TPS) ≥1, and of the 4 MMR proficient cases, 3 were positive by CPS; 2 by TPS. Overall, only 1 of the 8 available for analysis failed to show PD-L1 positivity by CPS. In contrast, nonmedullary MMR-deficient carcinomas expressed PD-L1 in only 33% of tumors by CPS, and none by TPS. One medullary carcinoma was also EBV associated. Unlike 'medullary carcinomas' of the kidney, INI1 was retained in all 8 cases tested. In conclusion, medullary carcinomas are 3% of ACs, have a strong association with MMR-D, and may be less aggressive despite their larger size. PD-L1 expression appears to be closely associated with medullary ACs regardless of MMR status, and thus targeted therapies can be considered for all medullary carcinomas of this site.

New Potential Immune Biomarkers in the Era of Precision Medicine: Lights and Shadows in Colorectal Cancer

Genetic alterations in CRC have shown a negative predictive and prognostic role in specific target therapies. The onset of immunotherapy has also undergone remarkable therapeutic innovation, although limited to a small subgroup of patients, the MSI-H/dMMR, which represents only 5% of CRC. Research is moving forward to identify whether other biomarkers can predict response to ICIs, despite various limitations regarding expression and identification methods. For this purpose, TMB, LAG3, and PD-L1 expression have been retrospectively evaluated in several solid tumors establishing the rationale to design clinical trials with concurrent inhibition of LAG3 and PD-1 results in a significant advantage in PFS and OS in advanced melanoma patients. Based on these data, there are clinical trials ongoing in the CRC as well. This review aims to highlight what is already known about genetic mutations and genomic alterations in CRC, their inhibition with targeted therapies and immune checkpoints inhibitors, and new findings useful to future treatment strategies.

Diagnostic and Prognostic Roles of CDX2 Immunohistochemical Expression in Colorectal Cancers

The study is aimed to evaluate the diagnostic and prognostic role of the immunohistochemical expression of the Caudal-type homeobox transcription factor 2 (CDX2) in colorectal cancers (CRCs) through a meta-analysis. By searching relevant databases, 38 articles were eligible to be included in this study. We extracted the information for CDX2 expression rates and the correlation between CDX2 expression and clinicopathological characteristics. The estimated rates of CDX2 expression were 0.882 [95% confidence interval (CI) 0.774−0.861] and 0.893 (95% CI 0.820−0.938) in primary and metastatic CRCs, respectively. Furthermore, based on their histologic subtype, CDX2 expression rates of adenocarcinoma and medullary carcinoma were 0.886 (95% CI 0.837−0.923) and 0.436 (95% CI 0.269−0.618), respectively. There was a significant difference in CDX2 expression rates between adenocarcinoma and medullary carcinoma in the meta-regression test (p < 0.001). In addition, CDX2 expression was significantly lower in CRCs with the BRAFV600E mutation than in CRCs without mutation. Patients with CDX2 expression had better overall and cancer-specific survival rates than those without CDX2 expression. Thus, CDX2 is a useful diagnostic and prognostic marker CRCs.

The Complete Loss of p53 Expression Uniquely Predicts Worse Prognosis in Colorectal Cancer

p53 immunohistochemistry is considered an accurate surrogate marker reflecting the underlying TP53 mutation status and has utility in tumor diagnostics. In the present study, 269 primary CRCs were immunohistochemically evaluated for p53 expression to assess its utility in diagnostic pathology and prognostication. p53 expression was wild-type in 59 cases (23%), overexpressed in 143 cases (55%), completely lost in 50 cases (19%), and cytoplasmic in 10 cases (4%). p53 immunoreactivity was associated with tumor size (p = 0.0056), mucus production (p = 0.0015), and mismatch repair (MMR) system status (p < 0.0001). Furthermore, among CRCs with wild-type p53 expression, a significantly higher number of cases had decreased CDX2 than those with p53 overexpression (p = 0.012) or complete p53 loss (p = 0.043). In contrast, among CRCs with p53 overexpression, there were significantly fewer ALCAM-positive cases than p53 wild-type cases (p = 0.0045). However, no significant association was detected between p53 immunoreactivity and the “stem-like” immunophenotype defined by CDX2 downregulation and ALCAM-positivity. Multivariate Cox hazards regression analysis identified tubular-forming histology (hazard ratio [HR] = 0.17, p < 0.0001), younger age (HR = 0.52, p = 0.021), and female sex (HR = 0.55, p = 0.046) as potential favorable factors. The analysis also revealed complete p53 loss (HR = 2.16, p = 0.0087), incomplete resection (HR = 2.65, p = 0.0068), and peritoneal metastasis (HR = 5.32, p < 0.0001) as potential independent risk factors for patients with CRC. The sub-cohort survival analyses classified according to chemotherapy after surgery revealed that CRC patients with wild-type p53 expression tended to have better survival than those with overexpression or complete loss after chemotherapy. Thus, immunohistochemistry for p53 could be used for the prognostication and chemotherapy target selection of patients with CRC.

Prognostic Value of Programmed Death Ligand-1 Expression in Solid Tumors Irrespective of Immunotherapy Exposure: A Systematic Review and Meta-Analysis

BACKGROUND

The programmed cell death-1/programmed cell death ligand-1 (PD-L1) pathway, which plays a crucial role in cancer immune surveillance, is the target of several approved immunotherapeutic agents and is used as a predictive biomarker in some solid tumors. However, its use as a prognostic marker (i.e., regardless of therapy used) is not established clearly with available data demonstrating inconsistent prognostic impact of PD-L1 expression in solid tumors.

METHODS

We conducted a systematic literature search of electronic databases and identified publications exploring the effect of PD-L1 expression on overall survival and/or disease-free survival. Hazard ratios were pooled in a meta-analysis using generic inverse-variance and random-effects modeling. We used the Deeks method to explore subgroup differences based on disease site, stage of disease, and method of PD-L1 quantification.

RESULTS

One hundred and eighty-six studies met the inclusion criteria. Programmed cell death ligand-1 expression was associated with worse overall survival (hazard ratio 1.33, 95% confidence interval 1.26-1.39; p < 0.001). There was significant heterogeneity between disease sites (subgroup p = 0.002) with pancreatic, hepatocellular, and genitourinary cancers associated with the highest magnitude of adverse outcomes. Programmed cell death ligand-1 was also associated with worse overall disease-free survival (hazard ratio 1.19, 95% confidence interval 1.09-1.30; p < 0.001). Stage of disease did not significantly affect the results (subgroup p = 0.52), nor did the method of quantification via immunohistochemistry or messenger RNA (subgroup p = 0.70).

CONCLUSIONS

High expression of PD-L1 is associated with worse survival in solid tumors albeit with significant heterogeneity among tumor types. The effect is consistent in early-stage and metastatic disease and is not sensitive to method of PD-L1 quantification. These data can provide additional information for the counseling of patients with cancer about prognosis.

A high density of PD-L1-expressing immune cells is significantly correlated with favorable disease free survival in nonmetastatic colorectal cancer

The impact of immune cells (ICs) expressing various markers remains poorly understood in nonmetastatic colorectal cancer patients who have undergone colectomy. Here, we aimed to clarify the correlation between IC density and clinical parameters and survival.Programmed death protein-1 (PD-1), programmed cell death protein ligand-1 (PD-L1), clusters of differentiation (CD)-3, CD-8, and CD45RO immunostaining was performed for 421 patients using tissue microarray and automatic counting. Tumor stroma area immune density was assessed in comparison to clinical histological factors and surgical outcomes.High-density CD-8 expression was significantly associated with current smoking habits or a smoking history (P = .006). High-density of PD-1 expression was correlated with Lynch syndrome patients (P < .001) and with patients who did not consume alcohol (P = .034). A significant decrease in CR45RO expression density was associated with aging (P = .002 and r = -0.014), and high-density CD-3, CD-8, and PD-1 expression was significantly associated with right colon tumor location (P < .001). High CD-3 and PD-L1 expression was significantly associated with early tumor T-staging (P = .018 and P = .002). High-density PD-1 expression was significantly correlated with mucinous type adenocarcinoma (P = .027) and poor differentiation (P < .001). For treatment outcomes, multivariate analysis confirmed that patients exhibiting high-density PD-L1 expression possessed significantly longer disease free survival (adjusted hazard ratio: 0.752, 95% confidence interval [CI]: 0.61-0.92, P = .006) and overall survival (adjusted hazard ratio: 0.872, 95% CI: 0.75-1.91, P = .064)Significantly varied density in IC subsets was related to distinct demographic or clinic-histological factors. The presence of high-density PD-L1-expressing ICs is an independent favorable prognostic factor for disease free survival and overall survival among stage I to III colorectal cancer patients.

Significance of long non-coding RNA IFNG-AS1 in the progression and clinical prognosis in colon adenocarcinoma

Colon adenocarcinoma originates from adenoma and triggers serious healthy burdensome. lncRNAs develop a crucial role in the progression of colorectal carcinoma. In this study, we aimed to investigate the clinical value and potential role of lncRNA interferon (IFN) gamma antisense RNA 1 (IFNG-AS1) in colon adenocarcinoma. This study enrolled 95 colorectal adenoma patients, 128 colorectal adenocarcinoma patients, and 88 healthy individuals. The serum, tissue IFNG-AS1 expression levels were explored by real-time quantitative reverse transcription-PCR (RT-qPCR) assay. The receiver operator characteristic curve and Kaplan-Meier method were used to assess the clinical significance of IFNG-AS1. The chi-square test was used to analyze the association between tissue IFNG-AS1 and clinical characteristics. Functional experiments were conducted to delve into the effects of IFNG-AS1 on cellular activities (cell viability/migration/invasion). The target miRNA of IFNG-AS1 was also explored. IFNG-AS1 expression in both serum and tissue samples was elevated in patients. Serum IFNG-AS1 could diagnose colon adenoma and adenocarcinoma patients from the healthy control. High tissue IFNG-AS1 was correlated with several clinical characteristics and a shorter overall survival time. Silence of IFNG-AS1 could be available for repressing cellular capacities via the sponge to miR-627-3p. IFNG-AS1 was rised in colon adenocarcinoma and it was relevant to tumor size, TNM stage, and poor prognosis of patients. Beyond that, downregulated expression of IFNG-AS1 may repress malignant progression of colon adenocarcinoma by regulating miR-627-3p. IFNG-AS1 might be a potential diagnosis or prognosis predictor for colon adenocarcinoma patients.

A novel prognostic immunoscore based on The Cancer Genome Atlas to predict overall survival in colorectal cancer patients

Colorectal cancer (CRC) is highly prevalent worldwide. The relationship between the infiltration of immunocytes in CRC and clinical outcome has been investigated in recent years. The present study aims to construct a new prognostic signature using an immunocyte panel. Our novel prognostic immunoscore included 13 types of immunocytes, which were identified by least absolute shrinkage and selection operator (LASSO)-Cox regression. The time-dependent receiver operating characteristic (ROC) curve and Kaplan–Meier survival estimates were applied to evaluate the prognostic ability. Compared with the signature based on a single immune marker (i.e., CD8 mRNA expression and CD8⁺ expressing T cells), the novel prognostic immunoscore possessed better specificity and sensitivity of prognosis (area under the curves (AUCs) are 0.852, 0.856, and 0.774 for 1-, 2-, and 3-year survival times, respectively). Significant differences were identified between the high and low immunoscore groups in overall survival and disease-free survival in training and validation cohorts. Combining the immunoscore with clinical information may provide a more accurate prognosis for CRC. The immunoscore can identify patients with poor outcomes in the high Tumor Mutational Burden (TMB) group, who may benefit the most from immunotherapy. The immunoscore was also closely related to two immune checkpoints (i.e., PD-L1 and PD-1, r = 0.3087 and r = 0.3341, respectively). Collectively, our study demonstrates that the novel prognostic immunoscore reported here may be useful in distinguishing different prognoses and may improve the clinical management of patients with CRC.

Interpretable systems biomarkers predict response to immune-checkpoint inhibitors

Cancer cells can leverage several cell-intrinsic and -extrinsic mechanisms to escape immune system recognition. The inherent complexity of the tumor microenvironment, with its multicellular and dynamic nature, poses great challenges for the extraction of biomarkers of immune response and immunotherapy efficacy. Here, we use RNA-sequencing (RNA-seq) data combined with different sources of prior knowledge to derive system-based signatures of the tumor microenvironment, quantifying immune-cell composition and intra- and intercellular communications. We applied multi-task learning to these signatures to predict different hallmarks of immune responses and derive cancer-type-specific models based on interpretable systems biomarkers. By applying our models to independent RNA-seq data from cancer patients treated with PD-1/PD-L1 inhibitors, we demonstrated that our method to Estimate Systems Immune Response (EaSIeR) accurately predicts therapeutic outcome. We anticipate that EaSIeR will be a valuable tool to provide a holistic description of immune responses in complex and dynamic systems such as tumors using available RNA-seq data.

Association of PIK3CA mutation and PTEN loss with expression of CD274 (PD-L1) in colorectal carcinoma

Immunotherapy targeting the CD274 (PD-L1)/PDCD1 (PD-1) immune checkpoint axis has emerged as a promising treatment strategy for various cancers. Experimental evidence suggests that phosphatidylinositol-4,5-bisphosphonate 3-kinase (PI3K) signaling may upregulate CD274 expression. Thus, we hypothesized that PIK3CA mutation, PTEN loss, or their combined status might be associated with CD274 overexpression in colorectal carcinoma. We assessed tumor CD274 and PTEN expression by immunohistochemistry and assessed PIK3CA mutation by pyrosequencing in 753 patients among 4,465 incident rectal and colon cancer cases that had occurred in two U.S.-wide prospective cohort studies. To adjust for potential confounders and selection bias due to tissue availability, inverse probability weighted multivariable ordinal logistic regression analyses used the 4,465 cases and tumoral data including microsatellite instability, CpG island methylator phenotype, KRAS and BRAF mutations. PIK3CA mutation and loss of PTEN expression were detected in 111 of 753 cases (15%) and 342 of 585 cases (58%), respectively. Tumor CD274 expression was negative in 306 (41%), low in 195 (26%), and high in 252 (33%) of 753 cases. PTEN loss was associated with CD274 overexpression [multivariable odds ratio (OR) 1.83; 95% confidence interval (CI), 1.22–2.75; P = .004]. PIK3CA mutation was statistically-insignificantly (P = .036 with the stringent alpha level of 0.005) associated with CD274 overexpression (multivariable OR, 1.54; 95% CI, 1.03–2.31). PIK3CA-mutated PTEN-lost tumors (n = 33) showed higher prevalence of CD274-positivity (82%) than PIK3CA-wild-type PTEN-lost tumors (n = 204; 70% CD274-positivity) and PTEN-expressed tumors (n = 147; 50% CD274-positivity) (P = .003). Our findings support the role of PI3K signaling in the CD274/PDCD1 pathway.

Relationship between microsatellite status and immune microenvironment of colorectal cancer and its application to diagnosis and treatment

Due to advances in understanding the immune microenvironment of colorectal cancer (CRC), microsatellite classification (dMMR/MSI-H and pMMR/MSS) has become a key biomarker for the diagnosis and treatment of CRC patients and therefore has important clinical value. Microsatellite status is associated with a variety of clinicopathological features and affects drug resistance and the prognosis of patients. CRC patients with different microsatellite statuses have different compositions and distributions of immune cells and cytokines within their tumor microenvironments (TMEs). Therefore, there is great interest in reversing or reshaping CRC TMEs to transform immune tolerant "cold" tumors into immune sensitive "hot" tumors. This requires a thorough understanding of differences in the immune microenvironments of MSI-H and MSS type tumors. This review focuses on the relationship between CRC microsatellite status and the immune microenvironment. It focuses on how this relationship has value for clinical application in diagnosis and treatment, as well as exploring the limitations of its current application.

The Impact of Programmed Death-Ligand 1 Expression on the Prognosis of Early Stage Resected Non-Small Cell Lung Cancer: A Meta-Analysis of Literatures

Introduction

Previous studies have demonstrated that programmed cell death-ligand 1 (PD-L1) serves as biomarker for poor prognosis and survival in advanced-stage non-small cell lung cancer (NSCLC) patients. However, the merit of PD-L1 expression to predict the prognosis of early stage NSCLC patients who underwent complete resection remains controversial. In the present study, we performed a meta-analysis to investigate the relationship between PD-L1 expression and prognosis in patients with early stage resected NSCLC.

Methods

Electronic databases, including PubMed, EMBASE, and the Cochrane Library, were searched until July 23 2020 for studies evaluating the expression of PD-L1 and the prognosis of resected NSCLCs. Hazard ratios (HRs) with 95% confidence intervals (CIs) of overall survival (OS) and disease-free survival (DFS) were pooled and analyzed. Heterogeneity and publication bias analyses were also assessed.

Results

A total of 15 studies involving 3,790 patients were considered in the present meta-analysis. The pooled HR indicated that PD-L1 expression related to a much shorter DFS (HR = 1.56, 95% CI: 1.18-2.05, p < 0.01), as well a significantly worse OS (HR = 1.68, 95% CI: 1.29-2.18, p < 0.01). Furthermore, our analysis indicated that PD-L1 expression was significantly associated with gender (male vs. female: OR = 1.27, 95% CI:1.01-1.59, p = 0.038), histology (ADC vs. SCC: OR = 0.54, 95% CI:0.38-0.77, p = 0.001), TNM stage (I vs. II-III: OR = 0.45, 95% CI:0.34-0.60, p = 0.000), smoking status (Yes vs No: OR = 1.43, 95% CI:1.14-1.80, p = 0.002) and lymph node metastasis (N+ vs N-: OR = 1.97, 95% CI:1.26-3.08, p = 0.003).

Conclusions

The results of this meta-analysis suggest that PD-L1 expression predicts an unfavorable prognosis in early stage resected NSCLCs. The role of personalized anti-PD-L1/PD-1 immunotherapy in the adjuvant settings of resected NSCLC warrants further investigation.

PD-1 and PD-L2 expression predict relapse risk and poor survival in patients with stage III colorectal cancer

BACKGROUND

Immune responses have long been an area of interest in cancer research. In this study, the effects of programmed cell death-1 (PD-1) and its ligand (PD-L2) on the prognosis of colorectal cancer (CRC) were investigated.

METHODS

Primary tumour specimens of stage III CRC patients operated between 2002 and 2013 were assessed for PD-1 and PD-L2 expression and various clinicopathological and prognostic factors.

RESULTS

We observed a significant relationship between poor prognostic factors and PD-1/PD-L2 expression. These biomarkers were also found to serve as independent risk factors for LIR and MSI. In univariate analysis, relapse-free survival (RFS) and overall survival (OS) rates were found to be poor in PD-1 and PD-L2 positive patients. In multivariate analysis, these biomarkers were found to serve as independent poor prognostic factors for RFS and OS.

CONCLUSIONS

Our data indicate that PD-1 and PD-L2 may serve as independent prognostic survival parameters for CRC patients and may be employed for the design of targeted therapies.

Immunosuppressive role of Benzo[a]pyrene in induction of lung cancer in mice

AIM

Benzo[a]pyrene [BP] is one of the major carcinogenic precursors of cigarette smoke that primary affects the lung at its first proximity. The goal of the current research was to elucidate new mechanisms underlying the tumorigenic impact of oral BP in the lung of mice, with focus on immunosuppressive effects and cancer stemming properties.

METHODS

Female albino mice (n = 44) were divided into 2 groups: normal control and BP group. BP was administered orally to mice (50 mg/kg body weight), twice a week for four weeks in succession. At the end of experiment (22 weeks), gene expression were measured for transforming growth factor-β (TGF-β), cytotoxic T lymphocyte antigen-4 (CTLA-4), programmed death ligand 1(PD-L1), forkhead box protein P3 (FOXP3) and interleukin 12 (IL-12) and CD83+, CD8+ and CD166+ cell percentage were measured in lung tissue.

RESULTS

The results indicated the tumorigenic role of BP in the lung which was evidenced by histopathological examination. BP group also showed immunosuppressive role which evidenced by increased expression of lung TGF-β, CTLA-4, PD-L1, FOXP3 genes and decreased expression of lung IL-12 gene compared with normal control group. BP group also showed decreased CD83+ cells, CD8+ cells and increased number of CD166+ cells.

CONCLUSION

Our findings indicated that BP has immunosuppressive role in lung cancer besides increasing the percentage of cancer stem like cells.

B7-H3 immune checkpoint expression is a poor prognostic factor in colorectal carcinoma

Although PD-1/PD-L1 immunotherapy has been used successfully in treating many cancers, metastatic colorectal cancer (CRC) patients are not as responsive. B7-H3 is a promising target for immunotherapy and we found it to have the highest expression among B7-CD28 family members in CRC. Thus, the aim of the present study was to investigate B7-H3 expression in a large CRC cohort. B7-H3, B7-H4, and PD-L1 protein levels and differential lymphocyte infiltration were evaluated in tissue microarrays from 805 primary tumors and matched metastases. The relationships between immune markers, patient characteristics, and survival outcomes were determined. B7-H3 (50.9%) was detected in more primary tumors than B7-H4 (29.1%) or PD-L1 (29.2%), and elevated B7-H3 expression was associated with advanced overall stage. Co-expression of B7-H3 only with B7-H4 or PD-L1 was infrequent in primary tumors (6.3%, 5.7%, respectively). Moreover, B7-H3 in primary tumors was positively correlated with their respective expression at metastatic sites (ρ = 0.631; p < 0.001). No significant relationships between B7-H4 and PD-L1 and survival were observed; however, B7-H3 overexpression in primary tumors was significantly related to decreased disease-free survival. A positive relationship between B7-H3 expression and high density CD45RO T cell was observed in primary tumors, whereas B7-H4 and PD-L1 overexpression were related to CD3 T-cell infiltration. In conclusion, compared with B7-H4 and PD-L1, B7-H3 expression exhibited a higher prevalence and was significantly related to aggressiveness, worse prognosis and CD45RO T-cell infiltration in primary tumors. Further exploration of this potential target of immunotherapy in CRC patients is warranted.

Colorectal Adenocarcinomas Harboring ALK Fusion Genes: A Clinicopathologic and Molecular Genetic Study of 12 Cases and Review of the Literature

This study determined the frequency and the clinicopathologic and genetic features of colorectal carcinomas driven by oncogenic fusions of the anaplastic lymphoma kinase gene (ALK). Of the 8150 screened tumors, 12 (0.15%) were immunohistochemically ALK-positive with D5F3 antibody. These cancers harbored CAD-ALK (n=1), DIAPH2-ALK (n=2), EML4-ALK (n=2), LOC101929227-ALK (n=1), SLMAP-ALK (n=1), SPTBN1-ALK (n=4), and STRN-ALK (n=1) fusions, as detected by an RNA-based next-generation sequencing assay. ALK fusion carcinomas were diagnosed mostly in older patients with a 9:3 female predominance (median age: 72 y). All tumors, except a rectal one, occurred in the right colon. Most tumors were stage T3 (n=7) or T4 (n=3). Local lymph node and distant metastases were seen at presentation in 9 and 2 patients. These tumors showed moderate (n=6) or poor (n=3) glandular differentiation, solid medullary growth pattern (n=2), and pure mucinous morphology (n=1). DNA mismatch repair-deficient phenotype was identified in 10 cases. Tumor-infiltrating lymphocytes were prominent in 9 carcinomas. In 4 carcinomas, tumor cells showed strong, focal (n=3), or diffuse programmed death-ligand 1 immunoreactivity. CDX2 expression and loss of CK20 and MUC2 expression were frequent. CK7 was expressed in 5 tumors. Four patients died of disease within 3 years, and 7 were alive with follow-up ranging from 1 to 8 years. No mutations in BRAF, RAS, and in genes encoding components of PI3K-AKT/MTOR pathway were identified. However, 1 tumor had a loss-of-function PTEN mutation. Aberration of p53 signaling, TP53 mutations, and/or nuclear accumulation of p53 protein was seen in 9 cases. ALK fusion colorectal carcinomas are a distinct and rare subtype of colorectal cancers displaying some features of mismatch repair-deficient tumors.

Immune landscape and biomarkers for immuno-oncology in colorectal cancers

Recent advances in immuno-oncology have increased understanding of the tumor immune microenvironment (TIME), and clinical trials for immune checkpoint inhibitor treatment have shown remission and/or durable response in certain proportions of patients stratified by predictive biomarkers. The TIME in colorectal cancer (CRC) was initially evaluated several decades ago. The prognostic value of the immune response to tumors, including tumor-infiltrating lymphocytes, peritumoral lymphoid reaction, and Crohn's-like lymphoid reaction, has been well demonstrated. In this review, we describe the chronology of TIME research and review the up-to-date high-dimensional TIME landscape of CRC. We also summarize the clinical relevance of several biomarkers associated with immunotherapy in CRC, such as microsatellite instability, tumor mutational burden, POLE/POLD mutation, consensus molecular subtype, and programmed death-ligand 1 expression.

Frequency and clinicopathologic associations of DNA mismatch repair protein deficiency in ampullary carcinoma: Routine testing is indicated

BACKGROUND

The significance of DNA mismatch repair (MMR) deficiency in ampullary cancers (ACs) has not been established.

METHODS

In total, 127 ACs with invasive carcinomas measuring ≥3 mmthat had adequate tissue were analyzed immunohistochemically.

RESULTS

MMR loss was detected in 18% of ACs (higher than in colorectal cancers). Twelve tumors with MLH1-PMS2 loss were negative for BRAF V600E mutation, suggesting a Lynch syndrome association. MMR-deficient tumors (n = 23), comparedwith MMR-intact tumors (n = 104), showed a striking male predominance (male:female ratio, 4.7). Although the deficient tumors had slightly larger invasion size (2.7 vs 2.1 cm), they also had more expansile growth and less invasiveness, including less perineural invasion, and they ultimately had lower tumor (T) classification and less lymph node metastasis (30% vs 53%; P = .04). More important, patients who had MMR-deficient tumors had better clinical outcomes, with a 5-year overall survival rate of 68% versus 45% (P = .03), which was even more pronounced in those who had higher Tclassification (5-year overall survival, 69% vs 34%; P = .04). MMR deficiencyhad a statistically significant association with medullary phenotype, pushing-border invasion, and tumor-infiltrating immune cells, and it occurred more frequently in ampullary-duodenal type tumors. Programed cell death-ligand 1 (PD-L1) levels analyzed in the 22 MMR-deficient ACs revealed that all medullary carcinomas were positive. Nonmedullary MMR-deficient carcinomas expressed PD-L1 in 33% of tumors cells according to the criteria for a combined positive score ≥1, but all were negative according to the tumor proportion score≥1 method.

CONCLUSIONS

In ACs, MMR deficiency is even more frequent (18%) than in colon cancer and often has a Lynch-suggestive profile, thus routine testing is warranted. Male gender, pushing-border infiltration, ampullary-duodenal origin, medullary histology, and tumor-related inflammation have a significantly higher association with MMR deficiency. MMR-deficient tumors have less aggressive behavior. PD-L1 expression is common in medullary-phenotype ACs, thus immunotherapy should be considered at least for this group.

Loss of survival advantage for deficient mismatch repair in patients with advanced colorectal cancer may be caused by changes in prognostic value of CD8+T cell

Background

Patients with stage II deficient mismatch repair (dMMR) show a better prognosis than patients with colorectal cancer (CRC) with proficient mismatch repair (pMMR). However, this beneficial effect is decreased in advanced stages of the disease. This study was conducted to investigate the prognostic value of dMMR in different stage and alterations in the tumor microenvironment.

Methods

This was a matched retrospective cohort study. Thirty-two patients with stage III&IV dMMR matched with 32 patients with stage I&II dMMR and 64 patients with pMMR were evaluated. Immunohistochemistry analysis was performed for the 64 patients with dMMR to explore the expression and prognostic effect of CD3, CD4, CD8, and PD-L1.

Results

Patients with stage III–IV dMMR showed no advantage in overall survival (OS) and disease-free survival (DFS) compared to patients with pMMR (P = 0.244, P = 0.667). No expression differences in CD3, CD4, CD8, and PD-L1 at the center of the tumor (CT) or invasive margin (IM) were found between patients with stage I&II and stage III&IV dMMR. High CD3 expression at the CT and high CD3 an CD4 expression at the IM improved both OS and DFS. High CD8 expression showed opposite prognostic value in patients with stage I&II and III&IV dMMR. A similar tendency was observed for PD-L1 expression.

Conclusion

Patients with stage III–IV dMMR showed no prognostic advantage over patients with pMMR. Expression of CD3, CD4, CD8, and PD-L1 was similar between stage I&II and III&IV dMMR CRC. High CD3 expression at the CT and high CD3 and CD4 expression at the IM can significantly improve patient prognosis. The opposite prognostic tendency of CD8 and PD-L1 for patients with stage I&II and III&IV dMMR may be relevant to CD8+T cell exhaustion and functional changes at inhibitory immune checkpoints.

PD-L1 in small bowel adenocarcinoma is associated with etiology and tumor-infiltrating lymphocytes, in addition to microsatellite instability

Small bowel adenocarcinomas (SBAs) are often associated with poor prognosis and have limited therapeutic options. Programmed cell death protein-1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway blockade is an effective treatment in many microsatellite instability-high (MSI-H) solid tumors. We aimed at investigating PD-L1 and PD-1 expression in non-hereditary, non-ampullary SBAs, associated with celiac disease (CeD), Crohn's disease (CrD), or sporadic, recruited through the Small Bowel Cancer Italian Consortium. We assessed PD-L1 and PD-1 by immunohistochemistry in a series of 121 surgically resected SBAs, including 34 CeD-SBAs, 49 CrD-SBAs, and 38 sporadic SBAs. PD-L1 and PD-1 expression was correlated with several clinico-pathological features, such as the etiology, microsatellite instability status, and tumor-infiltrating lymphocyte (TIL) density. The prevalence of PD-L1 positivity according to combined positive score (CPS) was 26% in the whole cohort of SBAs, with significantly (p = 0.001) higher percentage (35%) in both CeD-SBAs and CrD-SBAs in comparison with sporadic SBAs (5%). CPS ≥ 1 SBAs were significantly (p = 0.013) more frequent in MSI-H cases (41%) than in non-MSI-H ones (18%); however, 15 CPS ≥ 1 microsatellite stable SBAs were also identified. CPS ≥ 1 SBAs showed higher TIL and PD-1+ immune cell density, more frequently medullary histotype, as well as a better outcome in comparison with CPS < 1 cases. This study demonstrates an increased proportion of PD-L1+ cases in both CeD-SBAs and CrD-SBAs in comparison with sporadic SBAs. In addition, the identification of a subset of PD-L1+ microsatellite stable SBAs supports the need to ascertain additional biomarkers of response to immune checkpoint inhibitors along with MSI-H.

Immune Checkpoint Inhibitors: A Promising Choice for Endometrial Cancer Patients?

Although around 80% of endometrial cancers are diagnosed at early stages and present with a 5-year survival rate exceeding 95%, patients with advanced and recurrent disease show a poor prognosis and low response rates to standard chemotherapy. In the era of targeted therapy, the great advances in the understanding of programmed death-ligand 1 (PD-L1) upregulation in cancer cells, which is responsible for tumor immune escape, have contributed to the increasing interest in immune checkpoint inhibitors as a promising strategy for the treatment of several refractory solid malignancies, including endometrial cancer. Several clinical trials have investigated the efficacy and safety of immune checkpoint inhibitors in endometrial cancer, which already led to the approval of the anti-programmed cell death protein 1 (anti-PD-1) antibody pembrolizumab as a satisfactory alternative for selected patients with unresectable or metastatic disease. As the future of cancer treatment will probably rely on combination therapy strategies, currently, innovative ongoing trials are exploring the potential role of immune checkpoint inhibitors associated with chemotherapy, radiotherapy, and other targeted therapies. Moreover, further research is warranted to discover new specific biomarkers that can accurately predict the response to immunotherapy.

Immunotherapy in gastrointestinal cancer: The current scenario and future perspectives

Gastrointestinal cancers include colorectal, gastric, oesophageal, pancreatic and liver cancers. They continue to be a significant cause of mortality and morbidity worldwide. Current treatment strategies include chemotherapy, surgery, radiotherapy and targeted therapies. Immunotherapy has recently been incorporated in treatment regimens for some gastrointestinal malignancies and research into different immune modifying treatments is being carried out in this context. Approaches to immune modulation such as vaccination, adoptive cell therapy and checkpoint inhibition have shown varying clinical benefit, with most of the benefit seen in checkpoint inhibition. This review summarises recent advances and future direction of immunotherapy in patients with gastrointestinal malignancies.

Prevalence of PD-L1 expression is associated with EMAST, density of peritumoral T-cells and recurrence-free survival in operable non-metastatic colorectal cancer

INTRODUCTION

Microsatellite instability (MSI) predict response to anti-PD1 immunotherapy in colorectal cancer (CRC). CRCs with MSI have higher infiltration of immune cells related to a better survival. Elevated Microsatellite Alterations at Tetranucleotides (EMAST) is a form of MSI but its association with PD-L1 expression and immune-cell infiltration is not known.

METHODS

A consecutive, observational cohort of patients undergoing surgery for CRC. EMAST and clinicopathological characteristics were investigated against PD-L1, as well as CD3 and CD8 expression in the invasive margin or tumour centre (Immunoscore). Difference in survival between groups was assessed by log rank test.

RESULTS

A total of 149 stage I-III CRCs patients, with a median follow up of 60.1 months. Patients with PD-L1+ tumours (7%) were older (median 79 vs 71 years, p = 0.045) and had EMAST+ cancers (OR 10.7, 95% CI 2.2-51.4, p = 0.001). Recurrence-free survival was longer in cancers with PD-L1+ immune cells (HR 0.35, 95% CI 0.16-0.76, p = 0.008, independent of EMAST) and high Immunoscore (HR 0.10, 95% CI 0.01-0.72, p = 0.022). Patients expressing PD-L1 in immune cells had longer disease-specific survival (HR 0.28, 95% CI 0.10-0.77, p = 0.014).

CONCLUSIONS

Higher Immunoscore (CD3/CD8 cells) and expression of tumour PD-L1 is found in CRCs with EMAST. Lymphocytic infiltrate and peritumoral PD-L1 expression have prognostic value in CRC.

Retrospective analysis of the prognostic value of PD-L1 expression and 18F-FDG PET/CT metabolic parameters in colorectal cancer

Background: It has been rarely reported whether ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake in colorectal cancer cells is associated with the expression of PD-L1. We performed a clinical pathology study to evaluate PD-L1 expression in patients undergoing surgical resection of colorectal cancer with preoperative ¹⁸F-FDG PET/CT imaging, with the aim of predicting the response of CRC patients to immune checkpoint inhibitors.

Material and Methods: A retrospective analysis of patients with CRC who underwent FDG-PET imaging before surgery was performed to measure the parameters of FDG-PET imaging: the maximum standardized uptake value (SUVmax), the metabolic tumor volume (MTV), and the total lesion glycolysis (TLG) were evaluated to determine whether each parameter was associated with clinical pathology. Tumor specimens were subjected to PD-L1 staining by immunohistochemistry. Analysis of whether there is a correlation between PD-L1 expression and ¹⁸F-FDG uptake parameters in CRC.

Results: PD-L1 expression level was significantly correlated with SUVmax, MTV3.0 and TLG3.0. Multivariate analysis showed that PD-L1 and TLG3.0 were independent predictors of poor DFS in patients with CRC (P=0.009; P=0.016), PD-L1 expression is closely related to the patient's lesion (TLG3.0) (P<0.01).

Conclusion: The results of this study indicate that there was a significant correlation between PD-L1 expression and TLG3.0 which suggested that FDG-PET could serve as a noninvasive tool to assess the tumor microenvironment and as a predictor of PD-L1 inhibitor activity to determine the optimal therapeutic strategy for CRC. High PD-L1 expression levels and high TLG3.0 are independent risk factors for DFS differences in CRC patients.

Immune classification for the PD-L1 expression and tumour-infiltrating lymphocytes in colorectal adenocarcinoma

Background

Colorectal adenocarcinoma is the third most common cancer worldwide and a leading cause of cancer-related death. The recent emergence of diverse immunotherapeutic agents has made it crucial to interpret a complex tumour microenvironment intermingled with tumour-infiltrating immune cells to predict the immunotherapeutic response rate. However, in colorectal adenocarcinoma, studies are lacking that provide detailed analyses of programmed death-ligand 1 (PD-L1) and tumour-infiltrating lymphocytes (TIL) to elucidate their prognostic values and to identify immunotherapy-targetable subgroups, preferably with multiple immune-related biomarkers. In the present study, we categorize colorectal adenocarcinomas into four types of tumour immune microenvironments according to PD-L1 expression and TIL, analyse their prognostic values, and propose an immunotherapy-targetable subgroup.

Methods

Formalin-fixed, paraffin-embedded tissue samples of surgically resected primary colorectal adenocarcinomas (n = 489) were obtained and arrayed on tissue microarray blocks. Immunohistochemical stains for PD-L1, programmed cell death protein 1 (PD-1), cluster of differentiation 8 (CD8), and deficient mismatch repair (dMMR) were performed and evaluated.

Results

Tumour microenvironment immune type (TMIT) I (PD-L1-positive tumour cells and CD8-high TIL) and type II (PD-L1-negative tumour cells and CD8-low TIL) showed the best and worst prognoses, respectively. PD-L1 overexpression was significantly associated with dMMR status. PD-L1 immunoreactivity was positively correlated with TIL having CD8 or PD-1 overexpression.

Conclusions

TMIT I subgroup showed stronger CD8/PD-L1/PD-1 signalling interaction compared to the other TMIT. Therefore, we propose that the TMIT I subgroup is a candidate TMIT to predict effective response rate for existing immune checkpoint inhibitors and determine targetable subgroups for emerging therapies.

Immunohistochemical Expression of Programmed Death Ligand-1 (PDL-1) in Colorectal carcinoma and Its Correlation with Stromal Tumor Infiltrating Lymphocytes

OBJECTIVES

Detection of Immunohistochemical (IHC) expression of PDL-1 by tumor cells and stromal tumor infiltrating lymphocytes (TILs) in colorectal carcinoma, to investigate the possibility of using it as a targeted therapy, as well as, correlation of this expression with the clinico-pathologic parameters of the tumors.

MATERIALS AND METHODS

Colorectal tissue sections were collected from 60 colectomy specimens were taken from Kasr El Ainy Hospital, Faculty of Medicine, Cairo University. Exclusion criteria included cases with missing data and cases who received chemotherapy or radiotherapy. IHC expression of PDL-1 was investigated in tumor cells (T) and stromal TILs separately. PDL-1 positivity was defined as PDL-1 expression on ≥ 5% of membranous positive cell staining of any intensity.

RESULTS

PDL-1 (T) expression was detected in 25% of cases and showed statistically significant correlation with higher tumor grade and right sided colon tumors (P value < 0.05). PD-L1 stromal TILs expression was detected in 38.3 % of cases. Insignificant statistical relation between Stromal TILs PDL-1 expression and the tumor extent (T) was detected (P value = 0.07), however, the expression of PDL-1 in lymphocytes was inversely proportional to the tumor extent (invasion). There were linear relation between PDL-1 expression stromal (TILs) (33.3%) and PDL-1 expression in tumor cells (28.2%) and positive lympho-vascular invasion but it was statistically insignificant (P value = 0.4 and 0.2 respectively). Despite there were no statistical relation between either PDL-1 (T) and PDL-stromal TILS and Perineural invasion (P value =1 and 0.5) but inverse relation was noticed with more PDL-1 expression in tumor cells (24.5%) and TILS (40.8%) with negative Perineural invasion.

CONCLUSION

Our results supported PDL-1 expression in CRC by both TC and TILs, with higher expression in subset of tumors that are high grade highlighting them as candidates for anti- PD-1/PDL-1 therapy.
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Metformin attenuates PD-L1 expression through activating Hippo signaling pathway in colorectal cancer cells

Programmed cell death ligand 1 (PD-L1) is a key suppressor of the cytotoxic immune response. In colorectal carcinoma (CRC), PD-L1 expression results in immune escape and poor prognosis. Extensive researches suggested that metformin had a potential efficacy of enhancing anti-tumor immune response in different types of cancer. However, the detail mechanisms underlying the efficacy in CRC are unclear. Here, we showed that metformin decreases PD-L1 and YAP1 expression in vitro and in vivo. After silencing or inhibiting YAP1 expression by Verteporfin (VP), the inhibitor of YAP1, the expression of PD-L1 were decreased in protein level in CRC cells. Furthermore, metformin directly phosphorylated YAP1 and restricted YAP1 to entry in the nucleus, so that PD-L1 was reduced via western blot and immunofluorescence assays in SW480 and HCT116 cells. Finally, subcutaneous xenotransplanted tumor models of HCT116 cells were established in BALB/c nude mice. Compared with the control group, PD-L1 and YAP1 expressions in tumor tissues, detected by immunohistochemistry, were reduced in the group of metformin treatment. These findings illuminate a new regulatory mechanism, metformin activates Hippo signaling pathway to regulate PD-L1 expression and suggests that metformin has the possibility to increase the efficacy of immunotherapy in human CRC.

Immune overdrive signature in colorectal tumor subset predicts poor clinical outcome

The prognostic value of immune cell infiltration within the tumor microenvironment (TME) has been extensively investigated via histological and genomic approaches. Based on the positive prognostic value of T cell infiltration, Immunoscore has been developed and validated for predicting risk of recurrence for colorectal cancer (CRC). Also, association between a consensus T helper 1 (Th-1) immune response and favorable clinical outcomes has been observed across multiple cancer types. Here, we reanalyzed public genomic data sets from The Cancer Genome Atlas (TCGA) and NCBI Gene Expression Omnibus (NCBI-GEO) and performed multispectral immunohistochemistry (IHC) on a cohort of colorectal tumors. We identified and characterized a risk group, representing approximately 10% of CRC patients, with high intratumoral CD8+ T cell infiltration, but poor prognosis. These tumors included both microsatellite instable (MSI) and stable (MSS) phenotypes and had a high density of tumor-associated macrophages (TAMs) that expressed CD274 (programmed death-ligand 1 [PD-L1]), TGF-β activation, and an immune overdrive signature characterized by the overexpression of immune response and checkpoint genes. Our findings illustrate that CRC patients may have poor prognosis despite high CD8+ T cell infiltration and provide CD274 as a simple biomarker for identifying these patients.

Current and Future Horizons of Patient-Derived Xenograft Models in Colorectal Cancer Translational Research

Our poor understanding of the intricate biology of cancer and the limited availability of preclinical models that faithfully recapitulate the complexity of tumors are primary contributors to the high failure rate of novel therapeutics in oncology clinical studies. To address this need, patient-derived xenograft (PDX) platforms have been widely deployed and have reached a point of development where we can critically review their utility to model and interrogate relevant clinical scenarios, including tumor heterogeneity and clonal evolution, contributions of the tumor microenvironment, identification of novel drugs and biomarkers, and mechanisms of drug resistance. Colorectal cancer (CRC) constitutes a unique case to illustrate clinical perspectives revealed by PDX studies, as they overcome limitations intrinsic to conventional ex vivo models. Furthermore, the success of molecularly annotated "Avatar" models for co-clinical trials in other diseases suggests that this approach may provide an additional opportunity to improve clinical decisions, including opportunities for precision targeted therapeutics, for patients with CRC in real time. Although critical weaknesses have been identified with regard to the ability of PDX models to predict clinical outcomes, for now, they are certainly the model of choice for preclinical studies in CRC. Ongoing multi-institutional efforts to develop and share large-scale, well-annotated PDX resources aim to maximize their translational potential. This review comprehensively surveys the current status of PDX models in translational CRC research and discusses the opportunities and considerations for future PDX development.

PD-L1 is a double-edged sword in colorectal cancer: the prognostic value of PD-L1 depends on the cell type expressing PD-L1

PURPOSE

To investigate the associations between programmed cell death ligand-1 (PD-L1) on tumor cells (TCs) or PD-L1 on tumor-infiltrating immune cells (TIICs) and the microsatellite instability (MSI) status in colorectal cancer (CRC).

METHODS

In total, 238 CRC patients were enrolled. PD-L1 expression and MSI status were studied by immunohistochemical staining and polymerase chain reaction. The χ2 test was used to compare characteristics. The Kaplan-Meier method was used for survival analysis. Cox proportional hazards models were used to determine the prognostic influence of clinicopathological factors.

RESULTS

Eighteen patients (7.6%) were had MSI-high (MSI-H) CRC. The number of patients with PD-L1 expression on TCs, stromal TIICs and intraepithelial TIICs was 13 (5.5%), 64 (26.9%) and 45 (18.9%), respectively. The MSI-H phenotype was significantly associated with younger age, right sidedness, mucinous component, high grade, stromal TIICs expressing PD-L1 (P = 0.042) and intraepithelial TIICs expressing PD-L1 (P < 0.001), but not TCs expressing PD-L1. PD-L1-expressing TCs were an independent marker of poor prognosis [hazard ratio (HR) = 3.387, P = 0.003], and PD-L1-expressing stromal TIICs were an independent marker of good prognosis (HR = 0.551, P < 0.001).

CONCLUSIONS

PD-L1-expressing TCs were a marker of poor prognosis; in contrast, PD-L1-expressing TIICs were a marker of good prognosis. The MSI-H phenotype was associated with the presence of PD-L1-expressing TIICs, but not of PD-L1-expressing TCs.

Expression of vascular endothelial growth factor as a predictor of complete response for preoperative chemoradiotherapy in rectal cancer

Biomarkers that predict tumor response before surgical treatment are necessary to help select patients for preoperative chemoradiotherapy for rectal cancer. However, no definite predictive biomarker has been established. This study explored programmed death-ligand 1 (PD-L1), epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), p-signal transducer and activator of transcription 3 (p-STAT3), and death-domain associated protein as predictive biomarkers with regard to preoperative chemoradiotherapy in rectal cancer.Formalin-fixed paraffin-embedded cancer tissues from pretreatment biopsies from 31 patients who underwent preoperative chemoradiotherapy were studied. The biomarkers were evaluated by immunohistochemistry.PD-L1 positivity was found in 22.6% of 31 patients and complete response (CR) showed 33.3% and non-CR showed 18.2%. EGFR positivity was found in 71.0% of 31 patients and CR showed 88.9% and non-CR showed 73.6%. VEGF positivity was found in 83.9% of 31 patients and CR showed 88.9% and non-CR showed 81.8%. p-STAT3 positivity was found in 80.6% of 31 patients and CR showed 88.9% and non-CR showed 77.3%. On multiple logistic regression analysis, only VEGF expression was found to be a significant predictive factor for CR (P = .001). VEGF expression in pretreatment biopsies might be a predictive marker for CR after preoperative chemoradiation in rectal cancer.Although there is a restriction of small sample size, our finding suggested that this study can be foundation for a larger further study for biomarkers which can predict neoadjuvant therapy response of specimens obtained for diagnosis before surgery.

miRNA-148a-3p Regulates Immunosuppression in DNA Mismatch Repair-Deficient Colorectal Cancer by Targeting PD-L1

Immunotherapy against the interaction between programmed cell death 1/programmed cell death ligand 1 (PD-L1) has emerged as a promising strategy for colorectal cancer with mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H). The study aimed to identify miRNAs that posttranscriptionally control PD-L1 expression on tumor cells and also regulate immune evasion. A comprehensive miRNA screening using The Cancer Genome Atlas (TCGA) dataset (n = 260) combined with eight different miRNA target prediction programs resulted in the identification of a tumor suppressive miRNA, miR-148a-3p, as a potential negative regulator of PD-L1 expression, particularly in dMMR/MSI-H colorectal cancer. Using multiple cohorts of colorectal cancer, including TCGA data, a microarray dataset (n = 148), and formalin-fixed, paraffin-embedded samples (n = 395), we found that the expression of miR-148a-3p was decreased in dMMR/MSI-H tumors, correlating inversely with PD-L1 levels. We demonstrate that miR-148a-3p directly binds to the 3'-untranslated region of PD-L1, thereby reducing whole-cell and cell surface PD-L1 levels in HCT116 and SW837 cell lines. Overexpression of miR-148a-3p repressed IFNγ-induced PD-L1 expression on tumor cells and consequently diminished T-cell apoptosis in a coculture model of IL2-activated T cells and IFNγ-treated tumor cells. In conclusion, our data support a regulatory mechanism of PD-L1 expression on tumor cells and immune suppression via miR-148a-3p downregulation in colorectal cancer. IMPLICATIONS: This study provides novel evidence that miR-148a-3p negatively regulates tumor cell PD-L1 expression and decreased levels of miR-148a-3p contributes to the immunosuppressive tumor microenvironment.

The Prognostic and Clinicopathological Roles of PD-L1 Expression in Colorectal Cancer: A Systematic Review and Meta-Analysis

Background: Studies evaluating the prognostic significance of programmed death-ligand 1 (PD-L1) expression in colorectal cancer (CRC) are limited and remain controversial. This meta-analysis was conducted in order to evaluate the clinicopathological and prognostic significance of PD-L1 expression in CRC patients.

Methods: A comprehensive search was performed against the Medline/PubMed, Embase, Cochrane Library, Web of Science (WoS) and Scopus databases. Data were extracted with name of the first author, year of publication, country of origin, tumor type, number of cases, staining method, cut-off values, PD-L1 positive expression, clinicopathological parameters, outcome, and quality assessment score, and statistical analysis was conducted using Review Manager Version 5.3 (Revman the Cochrane Collaboration; Oxford, England) and STATA version 14 (Stata Corporation; College Station, TX, USA).

Results: Ten studies were included in this meta-analysis, in which the pooled hazard ratio (HR) showed that PD-L1 expression in tumor cells was significantly associated with a poor overall survival (HR = 1.50, 95% CI 1.05–2.13, P = 0.03). The pooled HR for disease-free survival (DFS) indicated that PD-L1 expression was significantly associated with shorter DFS (HR = 2.57, 95% CI 1.40–4.75, P = 0.002). The pooled odds ratios (ORs) showed that PD-L1 expression was associated with poor differentiation (OR = 3.47, 95% CI 1.37–8.77, P = 0.008) and right colon cancer (OR = 2.38, 95% CI 1.57–3.60, P < 0.0001). However, the expression of PD-L1 was independent of gender, age, tumor size, tumor stage, lymph node metastasis, and tumor-node metastasis stage.

Conclusion: This meta-analysis indicated that a high level of PD-L1 expression might be a biomarker for a poor prognosis in CRC patients. This information may be helpful for clinicians to stratify CRC patients for anti-PD-1/PD-L1 therapy, particularly patients with microsatellite instability high (MSI-H).

Molecular Diagnostics in Colorectal Carcinoma: Advances and Applications for 2018

The molecular pathogenesis and classification of colorectal carcinoma are based on the traditional adenomaecarcinoma sequence, serrated polyp pathway, and microsatellite instability (MSI). The genetic basis for hereditary nonpolyposis colorectal cancer is the detection of mutations in the MLH1, MSH2, MSH6, PMS2, and EPCAM genes. Genetic testing for Lynch syndrome includes MSI testing, methylator phenotype testing, BRAF mutation testing, and molecular testing for germline mutations in MMR genes. Molecular makers with predictive and prognostic implications include quantitative multigene reverse transcriptase polymerase chain reaction assay and KRAS and BRAF mutation analysis. Mismatch repair-deficient tumors have higher rates of programmed death-ligand 1 expression. Cell-free DNA analysis in fluids are proving beneficial for diagnosis and prognosis in these disease states towards effective patient management.