Prevalence of PD-L1 expression is associated with EMAST, density of peritumoral T-cells and recurrence-free survival in operable non-metastatic colorectal cancer.
ABSTRACT: 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.
Project description:The serrated neoplasia pathway accounts for approximately 20% of colorectal carcinomas (CRCs). Sessile serrated adenomas (SSAs), the main precursor lesion of the serrated pathway, are molecularly driven by MLH1 promoter methylation and microsatellite instability (MSI) in their progression to CRC. MSI-high (MSI-H) lesions are highly immunogenic and associated with a high density of tumor-infiltrating lymphocytes. Our study's aim was to determine how the kinetics of this immune environment relates to SSAs in their progression through low-grade (SSA-LD) to high-grade dysplasia (SSA-HD) and CRC. We analyzed 74 cases (16 CRCs, 14 SSAs-HD, and 44 SSAs-LD). Cases of hyperplastic polyp and SSA without dysplasia were analyzed for comparison. MSI status, intraepithelial lymphocyte (IEL) density, and immune checkpoint expression were assessed by immunohistochemistry for mismatch repair proteins, CD3, and PD-1/PD-L1, respectively. Average IEL density was 12, 18.6, 21.6, and 31 for SSA, SSA-LD, SSA-HD, and CRC, respectively, as opposed to 8.1 in normal colon (P < .0001). Average PD-1/PD-L1 lymphocytic expression was 1.1/1.0, 1.2/2.9, 4.8/6.9, and 12.4/15.2 in SSA, SSA-LD, SSA-HD, and CRC, respectively, compared with 0.5/0 in normal crypts (P < .0001). IEL and PD-1/PD-L1 lymphocytic expression values of MSI-H lesions were 22.6, 27.7, and 36.8, and 3/6.5, 6.2/10.6, and 18.3/17.6 in MSI-H SSA-LD, SSA-HD, and CRCs, respectively (P ranged from .0478 to .3529). PD-L1 epithelial expression was positive in 40% of SSAs, 59.1% of SSAs-LD, 100% of SSAs-HD, and 60% of CRCs (P < .0001). Increased IELs and PD-1/PD-L1 expression correlate with sequential progression of SSAs, through development of cytologic dysplasia, to CRC and MSI-H status.
Project description:BACKGROUND:Microsatellite unstable colorectal cancers (MSI+ CRCs) expressing PD-L1, respond to anti-PD-1 or anti-PD-L1 checkpoint blockade, whereas microsatellite-stable tumors do not respond the same. Our aim was to examine how the immune landscape relates to different aspects of the CRC's biology, including neoepitope burden. METHODS:We used TCGA data to stratify patients based on a cytolytic T-cell activity expression index and correlated immune cytolytic activity (CYT) with mutational, structural, and neoepitope features of each tumor sample. The expression of several immune checkpoints was verified in an independent cohort of 72 CRC patients, relative to their MSI status, using immunohistochemistry and RT-qPCR. RESULTS:CRC exhibits a range of intertumoral cytolytic T-cell activity, with lower cytolytic levels in the tumor, compared to the normal tissue. We separated CRC patients into CYT-high and CYT-low subgroups. High cytolytic activity correlated with increased mutational load in colon tumors, the count of MHC-I/-II classically defined and alternatively defined neoepitopes, high microsatellite instability and deregulated expression of several inhibitory immune checkpoints (VISTA, TIGIT, PD-1, IDO1, CTLA-4, and PD-L1, among others). Many immune checkpoint molecules (IDO1, LAG3, TIGIT, VISTA, PD-1, PD-L1 and CTLA-4) expressed significantly higher in MSI+ CRCs compared to MSS tumors. The expression of Treg markers was also significantly higher in CYT-high tumors. Both individual and simultaneous high levels of CTLA-4 and PD-L1 had a positive effect on the patients' overall survival. On the reverse, simultaneous low expression of both genes led to a significant shift towards negative effect. Assessed globally, CYT-low CRCs contained more recurrent somatic copy number alterations. PD-L1 protein was absent in most samples in the independent cohort and stained lowly in 33% of MSI CRCs. PD-L1+ CRCs stained moderately for CD8 and weakly for FOXP3. CYT-high colon tumors had higher TIL load, whereas CYT-high rectum tumors had higher TAN load compared to their CYT-low counterparts. CONCLUSIONS:Overall, we highlight the link between different genetic events and the immune microenvironment in CRC, taking into consideration the status of microsatellite instability. Our data provide further evidence that MSI+ and CYT-high tumors are better candidates for combinatorial checkpoint inhibition.
Project description:Microsatellite instability (MSI) is a hallmark of mismatch repair (MMR) deficiency. High levels of MSI at mononucleotide and dinucleotide repeats in colorectal cancer (CRC) are attributed to inactivation of the MMR genes, hMLH1 and hMSH2. CRC with low levels of MSI (MSI-L) exists; however, its molecular basis is unclear. There is another type of MSI--elevated microsatellite alterations at selected tetranucleotide repeats (EMAST)--where loci containing [AAAG](n) or [ATAG](n) repeats are unstable. EMAST is frequent in non-CRCs; however, the incidence of EMAST and its cause in CRC is not known. Here, we report that MutS homologue 3 (MSH3) knockdown or MSH3-deficient cells exhibit the EMAST phenotype and low levels of mutations at dinucleotide repeats. About 60% of 117 sporadic CRC cases exhibit EMAST. All of the cases defined as MSI-H (16 cases) exhibited high levels of EMAST. Among 101 non-MSI-H cases, all 19 cases of MSI-L and 35 of 82 cases of MSS exhibited EMAST. Although non-MSI-H CRC tissues contained MSH3-negative tumor cells ranging from 2% to 50% of the total tumor cell population, the tissues exhibiting EMAST contained more MSH3-negative cells (average, 31.5%) than did the tissues not exhibiting EMAST (8.4%). Taken together, our results support the concept that MSH3 deficiency causes EMAST or EMAST with low levels of MSI at loci with dinucleotide repeats in CRC.
Project description:Most tumors of patients with Lynch syndrome and a fraction of sporadic colorectal cancers (CRCs) exhibit high levels of microsatellite instability (MSI) at mono- and dinucleotide repeat loci. A different type of instability, elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) has been found in non-colonic cancers. Our previous study demonstrated that EMAST is common in sporadic CRC. Here, we focused on the relationships between EMAST and other genomic instability parameters or clinicopathological features in an unselected series of 88 sporadic CRCs. Of the tumors in the sample, 4 (4.5%) were MSI-high (MSI-H), 9 (10.2%) were MSI-low (MSI-L) and 75 (85.2%) were microsatellite stable. EMAST status was determined using 7 EMAST markers. Fifty-three (60.2%) tumors without MSI-H showed instability at >or=1 EMAST loci. All 4 MSI-H tumors showed instability at several EMAST loci. Instability profiles of MSI-H tumors at EMAST loci were more complex than those of non-MSI-H tumors. A tendency of positive association was observed between MSI-L and EMAST (P=0.023). The frequency of loss of heterozygosity (LOH) for the 14 loci in EMAST-positive tumors was significantly higher than negative tumors (P=0.048). Among the clinicopathological parameters, only tumor location at the distal colon was associated with EMAST-negative tumors (P=0.0084, one-tailed). A relatively higher frequency of well-differentiated adenocarcinomas was observed in EMAST tumors as opposed to non-EMAST tumors, though the survival rate was similar. These results suggest that overlapping mechanisms that cause MSI-L, EMAST and LOH in CRCs may exist.
Project description:<h4>Background</h4>The aim of this study was to evaluate how programmed death-ligand-1 (PD-L1) expression is linked to the immunoscore in the context of the tumor microenvironment and to assess the differential prognostic value of PD-L1 expression according to the immunoscore in 153 patients with microsatellite instability-high (MSI-H) advanced gastric cancer (GC).<h4>Results</h4>We found that T-PD-L1 (+) and I-PD-L1 (+) were significantly associated with a high immunoscore. The integrated PD-L1 expression of tumor and immune cells was not significantly correlated with the overall survival (OS) of patients. However, a combined survival analysis of PD-L1 expression and immunoscore revealed four distinct subgroups with a statistically significant difference in OS. That is, the PD-L1 (+)/immunoscoreLow group showed the worst and the PD-L1 (+)/immunoscoreHigh group showed the best prognosis. Furthermore, a multivariate analysis revealed that the combined status of PD-L1 expression and immunoscore was an independent and significant prognostic factor for OS in patients with MSI-H GC.<h4>Materials and methods</h4>The immunoscore was quantified by the number of high-density areas of CD3+ and CD8+ tumor infiltrating lymphocytes both in the tumor regions and compartments (i.e., epithelial and stromal compartments of the tumor center and the invasive front), the scores of which range from I0 to I8. By using immunohistochemistry, the expression of PD-L1 was also analyzed in tumor cells (T-PD-L1) and immune cells (I-PD-L1) using four different cut-off values (1%, 5%, 10% and 50%).<h4>Conclusions</h4>Our study revealed that PD-L1 expression is associated with the corresponding immunoscore and that the immunoscore can be a relevant marker for the determination of the prognostic role of PD-L1 expression in MSI-H GCs.
Project description:<h4>Background</h4>The aim of this study was to reveal the clinicopathological and molecular characteristics of microsatellite instability-high (MSI-H) colorectal cancers (CRCs) showing programmed death ligand-1 (PD-L1) positivity, which are good candidates for anti-PD-1/PD-L1 immunotherapy.<h4>Methods</h4>The PD-L1 expression status of 208 MSI-H CRCs was retrospectively analysed using immunohistochemistry. PD-L1 positivity in tumour cells (PD-L1+(T)) and PD-L1 positivity in immune cells (PD-L1+(I)) were separately evaluated.<h4>Results</h4>Programmed death ligand-1 positivity in tumour cells and PD-L1+(I) were observed in 26 (12.5%) and 62 (29.8%) MSI-H CRCs, respectively, and occasionally overlapped (n=12; 5.8%). Programmed death ligand-1 positivity tumours in MSI-H CRCs were significantly associated with older age, female sex, non-mucinous-type poor differentiation, infiltrating growth, tumour budding, advanced stage, CpG island methylator phenotype-high, MLH1 promoter methylation, and BRAF V600E mutations. However, PD-L1+(I) MSI-H CRCs were characterised by high-density tumour-infiltrating immune cells, including T cells and macrophages, and intense peritumoural lymphoid reactions. In patients with stage IV MSI-H CRCs who had undergone metastatectomy (n=4), the PD-L1 status of primary tumours was maintained in corresponding distant metastatic lesions.<h4>Conclusions</h4>In MSI-H CRCs, PD-L1+(T) and PD-L1+(I) are linked to a sporadic hypermethylated subtype and an immune cell-rich subtype, respectively. Potential differential therapeutic implications of PD-L1+(T) and PD-L1+(I) in CRCs should be further investigated.
Project description:Colorectal cancers (CRCs) with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) often have sustained responses to immune checkpoint inhibitors (ICIs) including selective monoclonal antibodies against Program Death 1 (PD-1), Programmed Death Ligand 1(PD-L1), and cytotoxic T lymphocyte associated antigen 4 (CTLA-4). However, a substantial fraction of dMMR CRCs do not respond or ultimately develop resistance to immunotherapy. The majority (~85%) of CRCs are MMR proficient (pMMR) or microsatellite stable (MSS) and lack response to ICIs. Understanding the biology and mechanisms underlying dMMR-associated immunogenicity is urgently needed for improving the therapeutic efficacy of immunotherapy on CRC. Compared to pMMR/MSS CRCs, dMMR/MSI CRCs typically have increased tumor mutational burden (TMB), lower response rate to 5-fluorouracil-based chemotherapy, distinctive immunological features such as high tumor-infiltrating lymphocytes (TILs), and better prognosis. Here, we review the current understanding of the clinical relevance of dMMR/MSI in CRCs, the molecular basis and rationales for targeting dMMR CRC with immunotherapy, and clinical approaches using ICIs as single agents or in combination with other therapies for MSI-H CRCs. Furthermore, we address the potential strategies to sensitize pMMR/MSS CRC to immunotherapy by converting an immunologically "cold" microenvironment into a "hot" one.
Project description:<h4>Background</h4>ARID1A is a component of the SWI/SNF complex, which controls the accessibility of proteins to DNA. ARID1A mutations are frequently observed in colorectal cancers (CRCs) and have been reported to be associated with high mutational burden and tumor PD-L1 expression in vitro.<h4>Aim</h4>To clarify the role of ARID1A mutation in CRC.<h4>Method and results</h4>We used next generation sequencing (NGS) and immunohistochemistry on clinically obtained samples. A total of 201 CRC tissues from Niigata University and Niigata Center Hospital were processed by NGS using the CANCERPLEX panel. Immunohistochemistry for ARID1A, PD-L1, MLH1, and MSH2 was performed on 66 propensity-matched (33 microsatellite instability-high [MSI-H] and 33 microsatellite-stable [MSS]) cases among 499 cases from Kyushu University. TCGA data were downloaded from cBioPortal. NGS showed significantly more mutations in ARID1A mutated CRCs (p = 0.01), and the trend was stronger for right-sided CRCs than left-sided. TCGA data confirmed these findings (p < 0.01). BRAF V600E and ATM mutations were also found at higher frequencies. Immunohistochemistry showed that 30% of MSI-H CRCs had ARID1A loss, while this was true in only 6% of MSS CRCs. In both MSI-H and MSS, PD-L1 expression by stromal cells was enhanced in the ARID1A-mutant groups (90% vs 39% in MSI-H, 100% vs 26% in MSS).<h4>Conclusion</h4>We found a higher mutational burden in ARID1A-mutant CRCs, and IHC study showed that ARID1A loss was correlated with high PD-L1 expression in stromal cells regardless of MSI status. These data support the idea that mutant ARID1A is a potential biomarker for CRCs.
Project description:<h4>Objectives</h4>We investigated the PD-L1 expression in colorectal cancer (CRC) and in its microenvironment.<h4>Results</h4>PD-L1 was expressed in neoplastic cells (NCs) and tumor-infiltrating immune cells (IICs). All samples PD-L1+ on NCs were also on IICs. Three types of cancers could be grouped: group A(NCs-/ IICs-); group B (NCs-/ IICs+); group C (NCs+/IICs+). To group A belong tumors characterized by poorly immunogenic competence, poor immune response but massive granulocyte infiltrate, justifying the absence of PD-L1 as an immunoinhibitor receptor. To Group B probably belong more immunogenic CRCs, justifying the strong IICs-mediated immune response, and up-regulation of PD-L1 expression only on IICs. To group C belong CRCs probably characterized by a large amount of tumor neoantigens resulting in a marked infiltration of lymphocytes and PD-L1 upregulation also in NCs.<h4>Materials and methods</h4>Sixty-three colorectal cancer specimens from a cohort of 61 patients were retrospectively reviewed. Thirty-seven MSS and 26 MSI-H CRCs enrolled in this study. Immunohistochemical staining to PD-L1 was performed by using MAb E1L3N.<h4>Conclusions</h4>Our study calls attention to the importance to assess PD-L1 expression in tumor microenvironment also evaluating type and density of infiltrating immune cells to better stratify CRCs with different immunological patterns.
Project description:Immunotherapy is reportedly effective in a subset of colorectal cancers (CRCs) with high microsatellite instability (MSI-H). Exploring the expression patterns and clinical values of immunologic molecules is critical in defining the specific responsive candidates. Here, we performed comprehensive molecular profiling of the B7 and TNFR family genes across 6 CRC datasets with over 1,000 patients' details using cBioPortal TCGA data. About 20% of patients had B7 and TNFR family gene alterations. The frequency of B7 gene mutations (2.2%-5%) were similar to copy number alterations (0.53%-5.46%). TNFR amplifications were relatively more common (5.45-11.32%) than that of B7 (0.09-2.73%). B7 and TNFR gene mRNAs were upregulated in 26% of cases (102/379) and 16% of cases (61/379), respectively. The mRNA levels of B7 and TNFR genes were inversely correlated with promoter methylation status. Clinically, both B7-H3 and TNFSF7 mRNA overexpression were associated with unfavorable clinical outcomes, and the B7-H3 expression was increased gradually in cases with gene amplifications. Moreover, patients with MSI-H had significantly higher PD-L1 or PD-1 expression. Most importantly, in MSI-H group, patients with PD-L1 or PD-1 upregulation had poorer survivals than those with PD-L1/PD-1 downregulation. This is the first study drawing the immune landscapes of the co-stimulator B7 and TNFR families in CRC and showing that MSI-H patients with PD-1/PD-L1 upregulation are associated with poor clinical outcomes, providing potential markers to stratify patients responsive to immune checkpoint therapy.