Microsatellite Instability Subtype Research Articles

BRCA-mutated gastric adenocarcinomas are associated with chromosomal instability and responsiveness to platinum-based chemotherapy.

Homologous recombination defect is an important biomarker of chemotherapy in certain tumor types, and the presence of pathogenic or likely pathogenic mutations involving BRCA1 or BRCA2 (p-BRCA) mutations is the most well-established marker for the homologous recombination defect. Gastric cancer, one of the most prevalent tumor types in Asia, also harbors p-BRCA mutations. To investigate the clinical significance of p-BRCA mutations, we analyzed 366 gastric cancer cases through next-generation sequencing. We determined the zygosity of p-BRCA mutations based on the calculated tumor purity through variant allelic fraction patterns and investigated whether the presence of p-BRCA mutations is associated with platinum-based chemotherapy and a certain molecular subtype. Biallelic p-BRCA mutation was associated with better response to platinum-based chemotherapy than heterozygous p-BRCA mutation or wild type BRCA genes. The biallelic p-BRCA mutations was observed only in the chromosomal instability subtype, while all p-BRCA mutations were heterozygous in microsatellite instability subtype. In conclusion, patients with gastric cancer harboring biallelic p-BRCA mutations were associated with a good initial response to platinum-based chemotherapy and those tumors were exclusively chromosomal instability subtype. Further investigation for potential association with homologous recombination defect is warranted.

Prognostic and immune infiltration significance of ARID1A in TCGA molecular subtypes of gastric adenocarcinoma.

AT-rich interaction domain 1A (ARID1A) is an essential subunit of the switch/sucrose non-fermentable chromatin remodeling complex and is considered to be a tumor suppressor. The Cancer Genome Atlas (TCGA) molecular classification has deepened our understanding of gastric cancer at the molecular level. This study explored the significance of ARID1A expression in TCGA subtypes of gastric adenocarcinoma. We collected 1248 postoperative patients with gastric adenocarcinoma, constructed tissue microarrays, performed immunohistochemistry for ARID1A, and obtained correlations between ARID1A and clinicopathological variables. We then carried out the prognostic analysis of ARID1A in TCGA subtypes. Finally, we screened patients by random sampling and propensity score matching method and performed multiplex immunofluorescence to explore the effects of ARID1A on CD4, CD8, and PD-L1 expression in TCGA subtypes. Seven variables independently associated with ARID1A were screened out: mismatch repair proteins, PD-L1, T stage, differentiation status, p53, E-cadherin, and EBER. The independent prognostic variables in the genomically stable (GS) subtype were N stage, M stage, T stage, chemotherapy, size, and ARID1A. PD-L1 expression was higher in the ARID1A negative group than in the ARID1A positive group in all TCGA subgroups. CD4 showed higher expression in the ARID1A negative group in most subtypes, while CD8 did not show the difference in most subtypes. When ARID1A was negative, PD-L1 expression was positively correlated with CD4/CD8 expression; while when ARID1A was positive, this correlation disappeared. The negative expression of ARID1A occurred more frequently in the Epstein-Barr virus and microsatellite instability subtypes and was an independent adverse prognostic factor in the GS subtype. In the TCGA subtypes, ARID1A negative expression caused increased CD4 and PD-L1 expression, whereas CD8 expression appeared independent of ARID1A. The expression of CD4/CD8 induced by ARID1A negativity was accompanied by an increase in PD-L1 expression.

Microsatellite Instability and P53 Aberrant Expression in Gastric Adenocarcinoma: Immunohistochemical Assessment and Correlation with Clinico-pathological Characteristics

Background: Gastric cancer (GC) is among the five most frequent cancer worldwide, following lung, breast, colorectal, and prostate cancer. It is the 12th most prevalent cancer in both sexes in Egypt, accounting for 1.6% of all malignancies. Distinct molecular subtypes of gastric adenocarcinoma (e.g., microsatellite instable subtype and P53 aberrant subtype) have been reported by different classification systems. However, the relation of these molecular subtypes to different clinicopathological features is still controversial.
 Aim of the Work: To utilize the immunohistochemical expression of DNA MMR proteins (MLH1 and MSH2) and p53 to detect microsatellite unstable and P53 aberrant molecular types in gastric adenocarcinoma. Moreover, to correlate immunohistochemically detected microsatellite unstable and P53 aberrant molecular types of gastric carcinoma with different clinicopathological characteristics.
 Materials and Methods: The immunohistochemical expression of MLH1, MSH2 and P53 proteins was evaluated in 70 cases of gastric adenocarcinoma.
 Results: Microsatellite status/Mismatch repair status showed a statistically significant relation with WHO classification, tumor differentiation, lymph node status, and TNM staging. P53 aberrant type showed a statistically significant relation with tumor differentiation, depth of tumor invasion, lymph node status, and TNM staging.
 Conclusions and Recommendations: Microsatellite instable GC and P53 aberrant GC are two distinct molecular subtypes of gastric adenocarcinoma with distinct clinicopathological features and different prognostic outcomes. Microsatellite instable tumors are associated with good prognostic parameters while, P53 aberrant tumors are associated with poor prognostic parameters. Both subtypes could be detected using immunohistochemistry and could represent potential targets for future therapeutic agents.

Abstract 889: The efficacy and safety of PD-L1-specific CAR-T in advanced gastric cancer

Abstract [Purpose] Heterogeneity and the tumor microenvironment are major obstacles to overcoming incurable advanced gastric cancer (AGC). Although Epstein-Barr virus-positive and microsatellite instability subtypes can be detected early and properly treated, they are rare in AGC. In this regard, recent combinational therapy of immune checkpoint inhibitors (ICIs) such as PD-1/PD-L1 inhibitors and other various therapeutics has been tried, but there are clinically limited doses and drug resistance. We hypothesized that CAR-T targeting PD-L1, the common tumor-associated antigen (TAA), which expresses in most advanced cancer cells, would make a significant breakthrough in curing a solid tumor. This study aimed to evaluate the killing effects of anti-PD-L1 CAR-T against gastric cancer cell lines. Removal of PD-L1-expressing cells in the AGC TME will improve the clinical outcomes of current therapies. [Results] We constructed a second-generation PD-L1 CAR lentiviral vector targeting PD-L1, which has an intermediate affinity with PD-L1 in solid tumor TME. As the secondary signaling motif, CD28 was chosen and tested along with the CD3 zeta chain. The effector CAR-T, named Vax-CAR-T, specifically recognized the PD-L1-expressing AGC cell line, SNU638, and exhibited rapid and robust cytotoxic activity in vitro. When compared to untransduced T cells, the level of the CD25 activation marker was higher in Vax-CAR-T cells. Besides, the inhibitory markers of Tim3 and LAG3 were expressed even higher than the untransduced. Despite high Tim3 and LAG3 expression in the final manufacturing process, Vax-CAR-T cells significantly suppressed tumor growth in both bigger (>95mm3) and smaller (≤50mm3) AGC xenograft NSG mouse models. More importantly, Vax-CAR-T-treated mice have well tolerated the CAR-T therapy with no significant adverse events during the CRS monitoring period, 2 weeks after Vax-CAR-T injection and have gradually recovered weight gains 5 days after CAR-T cell injection. [Conclusion] We believe that a new autologous CAR-T targeting PD-L1 could be a promising new tool for removing heterogeneous solid tumors in TME, which would be a significant step forward in improving current conventional and immunotherapeutic strategies. Citation Format: Hye-Seong Park, Eun-Ji Choi, Jae-In Yu, Kyung-Sik Lee, Yeo-Jin Lim, Se-Ryeong Choi, Yoonjoo Choi, Bum Chan Park, Jae Eun Park, Mihwa Kim, Je-Jung Lee, Joon Haeng Rhee. The efficacy and safety of PD-L1-specific CAR-T in advanced gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 889.

Clinicopathologic Features and Prognostic Significance of Immunohistochemistry and In Situ Hybridization Based Molecular Classification in Gastric Carcinoma.

Gastric carcinoma (GC) is a highly heterogeneous disease with many subtypes that have different morphologic and molecular characteristics. In the current study, we analyzed immunohistochemical (IHC) and in situ hybridization (ISH) features of GCs and evaluated their association with prognosis and clinicopathological features. Three hundred cases analyzed by IHC and ISH for microsatellite stability, p53, e-cadherin, HER2, PD-L1 expression, and Epstein-Barr virus (EBV) status. Cases were classified into five subgroups based on expression profile. The relationships between subgroups, clinicopathological features, and survival were determined. Ten (3.3%) cases were classified as EBV-associated, 45 (15%) as microsatellite instable (MSI), 73 (24.3%) as EBV-/microsatellite-stable (MSS)/epithelial-mesenchymal-transformation (EMT)-like, 75 (25%) as EBV-/MSS/ non-EMT-like/p53+, and 97 (32.3%) as EBV-/MSS/non-EMT-like/p53-. The MSI subtype had the best overall survival (OS). In contrast, the EBV-/MSS/EMT-like subtype had the poorest OS. The MSI subtype was also related with old age of the patient and antrum-corpus localized tumors, whereas the EBV-/MSS/EMT-like was associated with young age, larger tumor size, and advanced stage presentation. PD-L1 positivity is highly correlated with MSI and EBV-associated subtypes. Our data demonstrated a link between IHC/ISH characteristics of GC and clinical outcomes. IHC/ISH based molecular classification may be helpful in predicting the survival.

Exploring associations between tumor mutational burden and survival in uterine cancers (220)

<b>Objectives:</b> Molecular profiling of tumors from patients with uterine cancer has led to new therapeutic options with the use of immunotherapy. The FDA approved pembrolizumab for patients with tumor mutational burden-high (TMB-H) (≥10 mutations/megabase [mut/Mb]) solid tumors. We characterized patients with uterine cancer who had undergone next-generation sequencing to describe tumor mutational burden, microsatellite instability, and clinical outcomes within different epithelial and molecular subtypes. <b>Methods:</b> A retrospective cohort study was performed on patients with uterine cancer who underwent Foundation One testing between 2015 and 2021 at a single academic institution. Demographic and clinical characteristics were identified, including age, race/ethnicity, stage, histology, molecular subtype, using The Cancer Genome Atlas molecular classification, microsatellite instability (MSI) status, TMB, and follow-up time in months. Kaplan-Meier curves and Cox regression analyses were used to estimate overall survival (OS) and progression-free survival (PFS) based on TMB, MSI, and molecular subtypes. <b>Results:</b> We identified 129 patients with uterine cancer with Foundation One testing results: 54 (41.9%) had endometrioid histology, 36 (27.9%) serous, six (4.7%) clear cell, 17 (13.2%) carcinosarcoma, five (3.9%) endometrial stromal sarcoma, five (3.9%) leiomyosarcoma, and six others (4.7%). The median age at diagnosis was 62 years. TMB was available for 106/129 patients: 71 (67.0%) had low TMB, 33 (31.1%) had intermediate, and two (1.9%) had high. TMB scores were higher among those with MSI (mean, 13.5±5.2) compared to those with microsatellite stable tumors (mean, 4.5±2.6; p<0.001). Mean TMB was highest among those with the MSI hypermutated molecular subtype (median 10, mean 31.7±52.4), followed by <i>POLE</i> ultra-mutated (median 10, mean 10.1±6.3), copy-number low (median 4, mean 5.1±3.6), and copy-number high (median 4, mean 4.0±1.7). Patients with MSI-high tumors had statistically significantly higher TMB compared to patients with copy-number high tumors (p=0.001). There was also a statistically significant difference between TMB from patients with <i>POLE</i> hypermutated tumors those with copy-number high (p<0.001) and those with copy-number low tumors (p=0.004). TMB was not an independent predictor of OS (p=0.61) or PFS (p=0.07) for the entire cohort, or for any particular molecular subtype. Among patients who developed recurrent uterine cancer, there was a significant difference in PFS (p=0.002) and OS (p=0.002) by molecular classification (Figure 1). <b>Conclusions:</b> TMB was not an independent predictor of PFS or OS for patients with primary or recurrent uterine cancer. There are significant differences in TMB in the TCGA molecular subgroups of uterine cancer. Further work is needed to determine how TMB within the various molecular subgroups of uterine cancers predicts response to therapy.

Association between c-type lectin-like receptor 2 and microsatellite instability in colorectal cancer: a cross-sectional study

BackgroundAs a transmembrane protein, C-type lectin-like receptor 2 (CLEC-2) is mainly expressed on platelets and released into plasma after platelet activation. Activated platelets participate in the regulation of innate immune cells. Patients with different microsatellite statuses have distinct immune profiles. This study aimed to investigate the association of plasma CLEC-2 levels with microsatellite status among colorectal cancer (CRC) patients.MethodsA cross-sectional analysis of 430 CRC patients from Harbin Medical University Cancer Hospital was conducted. CLEC-2 levels were measured with fasting venous blood samples drawn from each participant before any treatment. The microsatellite status was evaluated with DNA obtained from fresh frozen tumor tissue samples. The other clinical data were collected and recorded based on the medical system records.ResultsCLEC-2 levels were significantly higher among patients with high microsatellite instability phenotype than the stable microsatellite group, adjusting for other confounding variables.ConclusionsThe increased CLEC-2 is associated with the high microsatellite instability subtype of CRC.

BHLHE22 Expression Is Associated with a Proinflammatory Immune Microenvironment and Confers a Favorable Prognosis in Endometrial Cancer.

Endometrial cancer (EC) rates are rising annually. Additional prediction markers need to be evaluated because only 10–20% of EC cases show an objective response to immune-checkpoint inhibitors (ICIs). Our previous methylomic study found that BHLHE22 is hypermethylated in EC tissues and can be detected using a Pap-smear sample. BHLHE22, a basic helix loop helix transcription factor family member, is known as a transcriptional repressor and is involved in cell differentiation. However, the role of BHLHE22 in EC remains poorly understood. Herein, we analyzed BHLHE22 expression in 54 paired cancer and normal endometrial tissue samples, and confirmed with databases (TCGA, GTEx, and human protein atlas). We found that BHLHE22 protein expression was significantly downregulated in EC compared with normal endometrium. High BHLHE22 expression was associated with microsatellite-instable subtype, endometrioid type, grade, and age. It showed a significant favorable survival. BHLHE22 overexpression inhibited the proliferation and migration of EC cells. Functional enrichment analysis showed that BHLHE22 was significantly associated with immune-related pathways. Furthermore, BHLHE22 was positively correlated with proinflammatory leukocyte infiltration and expression of chemokine genes in EC. In conclusion, BHLHE22 regulates immune-related pathways and modulates the immune microenvironment of EC.

Gastric cancer molecular classification based on immunohistochemistry and in situ hybridization: Analysis in western patients after curative-intent surgery.

BACKGROUNDGastric cancer (GC) is a highly heterogeneous disease, and the identification of molecular subtyping of gastric adenocarcinoma emerged as a promising option to define therapeutic strategies and prognostic subgroups. However, the costs and technical complexity of molecular methodologies remains an obstacle to its adoption, and their clinical significance by other approaches needs further evidence.AIMTo evaluate the clinicopathological characteristics and long-term survival of GC based on the subgroups of molecular classification by immunohistochemistry (IHC) and in situ hybridization (ISH).METHODSWe retrospectively evaluated all patients who underwent D2-gastrectomy between 2009 and 2016 in a Western cohort of GC patients treated with curative intent. Microsatellite instability (MSI) status, E-cadherin, and p53 expression were analyzed by IHC, and Epstein-Barr virus (EBV) by ISH. Tissue microarrays were constructed for analysis. Clinicopathological characteristics and survival of GC were evaluated according to subtypes defined by The Cancer Genome Atlas (TCGA) Research Network Group and Asian Cancer Research Group (ACRG) classification systems.RESULTSA total of 287 GC patients were included. Based on IHC and ISH analysis, five profiles were defined as follows: E-cadherin aberrant (9.1%), MSI (20.9%), p53 aberrant (36.6%), EBV positivity (10.5%), and p53 normal (31%), which corresponded to tumors that showed no alteration in another profile. A flowchart according to the TCGA and ACRG classifications were used to define the subtypes, where clinical and pathological characteristics associated with GC subtypes were evidenced. Proximal location (P < 0.001), total gastrectomy (P = 0.001), and intense inflammatory infiltrate (P < 0.001) were characteristics related to EBV subtype. MSI subtype was predominantly associated with advanced age (P = 0.017) and the presence of comorbidities (P = 0.011). While Laurén diffuse type (P < 0.001) and advanced stage (P = 0.029) were related to genomically stable (GS) subtype. GS tumors and microsatellite stable/epithelial to mesenchymal transition phenotype subtype had worse disease-free survival (DFS) and overall survival (OS) than other subtypes. Conversely, MSI subtype of GC had better survival in both classifications. Type of gastrectomy, pT and the TCGA subtypes were independent factors associated to DFS and OS.CONCLUSIONThe IHC/ISH analysis was able to distinguish immunophenotypic groups of GC with distinct characteristics and prognosis, resembling the subtypes of the molecular classifications. Accordingly, this method of classification may represent a viable option for use in a clinical setting.

Human Leukocyte Antigen Class I Deficiency in Gastric Carcinoma: An Adaptive Immune Evasion Strategy Most Common in Microsatellite Instable Tumors.

Immune checkpoint inhibitor therapy is effective only for a subset of patients with gastric cancer. Impaired neoantigen presentation caused by deficiency of human leukocyte antigen class I (HLA-I) has been reported as a common mechanism of immune evasion which is associated with resistance to immune checkpoint blockade. To elucidate the significance of HLA-I deficiency in gastric cancer with special focus on microsatellite instable (MSI) and Epstein-Barr virus (EBV)-positive tumors, we examined HLA-I expression on tumor cells and correlated the results with clinicopathologic features, programmed death-ligand 1 (PD-L1) expression, and degree of tumor-infiltrating immune cells. This study included 58 MSI, 44 EBV-positive, and 107 non-EBV non-MSI tumors for comparison. The frequency of HLA-I deficiency (≥1% tumor cells) was significantly higher in MSI tumors (52%) compared with EBV-positive tumors (23%) and the other tumors (28%). In contrast, PD-L1 expression levels were highest in EBV-positive tumors, followed by MSI tumors, with the lowest prevalence in the other tumors in both Tumor Proportion Score and Combined Positive Score. HLA-I deficiency was significantly more frequent in advanced tumors (pT2-4) than in early tumors (pT1) in MSI and non-EBV non-MSI subtypes. In addition, the degree of CD8-positive cells infiltration was significantly reduced in HLA-I deficient tumor areas compared with HLA-I preserved tumor area within a tumor. Based on our observations, HLA-I, as well as PD-L1, should be considered as a common mechanism of immune escape especially in the MSI subtype, and therefore could be a biomarker predicting response to immune checkpoint inhibitor therapy in gastric cancer.

Genomic characteristics of endometrial cancer in China.

e17569 Background: Molecular classification of endometrial cancer has been applied in patient stratification and treatment strategy. Although the Cancer Genome Atlas project and other genomic studies have established comprehensive molecular classification, its genomic characteristics in Chinese endometrial cancer remain unclear. Methods: Tumor tissue and matched white blood cells from 316 patients with endometrial cancer underwent next-generation sequencing (NGS), which targeted the whole coding region of 733 or 381 genes. Endometrial cancer was classified into four subtypes according to genomic characteristics: polymerase (POLE) ultramutated, microsatellite instability (MSI), TP53 wild type (TP53wt), and TP53 mutant (TP53mut). Tumor mutation burden (TMB) was calculated based on the number of somatic single nucleotide variants and indels in examined coding regions. Deleterious or suspected deleterious genes were included for analysis. Genomic instability was also evaluated with Homologous Recombination Deficiency (HRD) score by over 10, 000 single-nucleotide polymorphisms distributed across human genome. HRD algorithm combined loss of heterozygosity score (LOH), telomeric allelic imbalance score (TAI) and large-scale state transition score (LST). Results: The 316 endometrial cancer patients were divided into four subtypes: POLE ultramutated (16, 5.06%), MSI tumors (70, 22.2%), TP53wt (131, 41.5%), and TP53mut (99, 31.3%). Median TMB was 26.5 mut/Mb in overall cohort and POLE ultramutated subtype possessed the highest TMB (181 mut/Mb), followed by MSI (54.1 mut/Mb), TP53mut (7.11 mut/Mb) and TP53wt (6.61 mut/Mb) subtypes. POLE, PTEN, LRP1B, BRCA2 and ATRX were the top frequently mutated genes in POLE ultramutated subtype, which mutation rate are more that 80%. The most frequent mutations were detected in ARID1A, PTEN, PIK3CA in MSI subtype, TP53, PIK3CA, PTEN in TP53mut subtype, and PTEN, PIK3CA, ARID1A in TP53wt subtype. HRD score was significantly higher in TP53mut subtype, followed by TP53wt, MSI and POLE ultramutated subtype (median HRD score, 21.7, 6.15, 3.65 and 0; P &lt; 0.001). Conclusions: Our study revealed the heterogeneous genomic characteristics of four molecular subtypes in Chinese endometrial cancer. POLE ultramutated and MSI subtypes display higher TMB. TP53mut subtype showed genome features of HRD and would likely benefit from HRD-targeted therapy.

Cytolytic activity score as a biomarker for antitumor immunity and clinical outcome in patients with gastric cancer.

BackgroundA simple measure of immune cytolytic activity (CYT) base on mRNA expression levels of two genes, GZMA and PRF1, was recently reported. Here, we aimed to evaluate the CYT score's potential as a measure of antitumor immunity and predictor of clinical outcome in gastric cancer (GC) patients.Materials and MethodsWe evaluated the correlations between tumor‐infiltrating immune cells and the CYT score in 238 GC samples from The Cancer Genome Atlas (TCGA). Next, we investigated CYT score associations with molecular subtypes, somatic mutation load, and immune checkpoint molecules in GC samples from TCGA and Asian Cancer Research Group (ACRG). Moreover, we evaluated the clinical significance of the CYT score calculated by reverse transcription (RT)‐quantitative PCR (qPCR) data in 123 GC samples and the association of the CYT score with the response to anti‐PD‐1 therapy in 7 GC samples from Kyushu University Hospital.ResultsThe CYT score positively correlated with the proportions of tumor‐infiltrating CD8+ T cells and macrophages and negatively correlated with the proportion of regulatory T cells in GC tissues. A high CYT score was associated with common immune checkpoint molecules, a high mutation, the Epstein–Barr virus subtype, and the microsatellite instability subtype in GC. Moreover, a low CYT score was a poor prognosis factor in patients with GC. Finally, the CYT score was higher in a responder to anti‐PD‐1 therapy compared to nonresponders.ConclusionThe CYT score reflects antitumor immunity and predicts clinical outcome in GC patients.

Clinicopathological characteristics of Epstein-Barr virus and microsatellite instability subtypes of early gastric neoplasms classified by the Japanese and the World Health Organization criteria.

Gastric cancer is a heterogenous disease with different phenotypes, genotypes, and clinical outcomes, including sensitivity to treatments and prognoses. Recent medical advances have enabled the classification of this heterogenous disease into several groups and the consequent analysis of their clinicopathological characteristics. Gastric cancer associated with Epstein–Barr virus (EBV) and microsatellite‐unstable tumors are considered to be the two major subtypes as they are clearly defined by well‐established methodologies, such as in situ hybridization and polymerase chain reaction‐based analyses, respectively. However, discrepancies in the histological diagnosis of gastric neoplasms remain problematic, and international harmonization should be performed to improve our understanding of gastric carcinogenesis. We re‐evaluated Japanese cases of early gastric cancer according to the current World Health Organization (WHO) criteria and classified them into genomic subtypes based on microsatellite instability (MSI) and EBV positivity to determine the initial genetic events in gastric carcinogenesis. A total of 113 Japanese early gastric cancers (including low‐ and high‐grade dysplasias) treated with endoscopic resection over 5 years were archived in our hospital. A histological re‐evaluation according to the WHO criteria revealed 54 adenocarcinomas, which were divided into 6 EBV‐positive (11.1%), 7 MSI‐high (MSI‐H, 13.0%), and 41 microsatellite stable cases (75.9%). MSI‐H adenocarcinoma was confirmed by an immunohistochemistry assay of mismatch repair proteins. Programmed death‐ligand 1 immunostaining with two antibodies (E1L3N and SP263) was positive in tumor cells of one MSI‐H adenocarcinoma case (1/7, 14.3%). The proportion of stained cells was higher with clone SP263 than with E1L3N. Histologically, EBV‐positive carcinomas were poorly differentiated (83.8%), and MSI‐H cancers were frequent in well to moderately differentiated adenocarcinoma (85.7%), indicating that the EBV‐positive subtype presented with high‐grade morphology even when an early lesion. Our study indicates that the WHO criteria are useful for subdividing Japanese early gastric cancers, and this subdivision may be useful for comparative analysis of precursor lesions and early carcinoma.

Maspin as a Prognostic Marker for Early Stage Colorectal Cancer With Microsatellite Instability.

Colorectal cancers are among the most common cancers and a leading cause of cancer death. In our pursuit to discover molecular markers for better characterization and precision theranostics of these cancers, we first conducted global deep proteome analyses and identified maspin (serpin B5, peptidase inhibitor 5) as an upregulated protein in tumor tissue. We then validated its expression in a large cohort of 743 patients with colorectal cancers of all stages and found that both cytoplasmic and nuclear expression varied widely between different patients. Comparison with clinicopathological features revealed that maspin expression levels correlate significantly only with mismatch repair (MMR) status but not with other features. To elucidate the prognostic significance of maspin, we analyzed two outcome-annotated cohorts, one of 572 early stage cancer patients and another of 93 late stage cancer patients. Kaplan–Meier survival, univariate, and multivariate analyses revealed that maspin overexpression predicts longer overall and disease-free survival for early stage microsatellite instability (MSI) subtype colorectal cancer, but there is no correlation with survival for patients with early stage cancer of the microsatellite stability (MSS) subtype or late stage cancer. Our study identifies maspin expression as an independent prognostic marker for risk stratification of early stage MSI subtype colorectal cancer and may provide guidance for improved therapeutic management.

Characterizing diversity in the tumor-immune microenvironment of distinct subclasses of gastroesophageal adenocarcinomas

Gastroesophageal adenocarcinomas (GEAs) are heterogeneous cancers where immune checkpoint inhibitors have robust efficacy in heavily inflamed microsatellite instability (MSI) or Epstein-Barr virus (EBV)-positive subtypes. Immune checkpoint inhibitor responses are markedly lower in diffuse/genome stable (GS) and chromosomal instable (CIN) GEAs. In contrast to EBV and MSI subtypes, the tumor microenvironment of CIN and GS GEAs have not been fully characterized to date, which limits our ability to improve immunotherapeutic strategies. Here we aimed to identify tumor-immune cell association across GEA subclasses using data from The Cancer Genome Atlas (N= 453 GEAs) and archival GEA resection specimen (N= 71). The Cancer Genome Atlas RNAseq data were used for computational inferences of immune cell subsets, which were correlated to tumor characteristics within and between subtypes. Archival tissues were used for more spatial immune characterization spanning immunohistochemistry and mRNA expression analyses. Our results confirmed substantial heterogeneity in the tumor microenvironment between distinct subtypes. While MSI-high and EBV+ GEAs harbored most intense T cell infiltrates, the GS group showed enrichment of CD4+ T cells, macrophages and B cells and, in ∼50% of cases, evidence for tertiary lymphoid structures. In contrast, CIN cancers possessed CD8+ T cells predominantly at the invasive margin while tumor-associated macrophages showed tumor infiltrating capacity. Relatively T cell-rich 'hot' CIN GEAs were often from Western patients, while immunological 'cold' CIN GEAs showed enrichment of MYC and cell cycle pathways, including amplification of CCNE1. These results reveal the diversity of immune phenotypes of GEA. Half of GS gastric cancers have tertiary lymphoid structures and are therefore promising candidates for immunotherapy. The majority of CIN GEAs, however, exhibit T cell exclusion and infiltrating macrophages. Associations of immune-poor CIN GEAs with MYC activity and CCNE1 amplification may enable new studies to determine precise mechanisms of immune evasion, ultimately inspiring new therapeutic modalities.

Early-onset gastric cancer is a distinct disease with worrisome trends and oncogenic features

BackgroundOverall the incidence of gastric cancer is declining in the United States; however, the incidence of early-onset gastric cancer is increasing. We sought to elucidate clinical and genomic characteristics and risk factors for early-onset gastric cancer compared with late-onset gastric cancer. MethodsWe utilized the Surveillance, Epidemiology, and End Results database (1973–2015), the Behavioral Risk Factor Surveillance Survey, and The Cancer Genome Atlas to characterize early-onset gastric cancer. ResultsThe incidence of early-onset gastric cancer increased during the study period and now comprises >30% of all gastric cancer in the United States. Early-onset gastric cancer was associated with higher grade (55.2 vs 46.9%), signet-ring cells (19.0 vs 10.4%), diffuse histology (25.7 vs 15.0%), and metastatic disease (49.5 vs 40.9%, all P < .01) compared with late-onset gastric cancer. Early-onset gastric cancer was more likely to be Epstein-Barr virus (7.7 vs 5.1%) or genomically stable (22.5 vs 8.1%) subtype, whereas late-onset gastric cancer was more likely to be microsatellite instability subtype (18.6 vs 5.6%; all P < .01). Risk factors for gastric cancer were less correlated with early-onset gastric cancer compared with late-onset gastric cancer. ConclusionThe incidence of early-onset gastric cancer has been steadily increasing in the United States, comprising >30% of new gastric cancer cases today. Early-onset gastric cancer is genetically and clinically distinct from traditional gastric cancer. Additional investigations are warranted to better understand this alarming phenomenon.

Analysis of the transcriptomic features of microsatellite instability subtype colon cancer

BackgroundProgrammed cell death protein 1(PD-1) blocking antibodies have been used to enhance immunity in solid tumors and achieve durable clinical responses with an acceptable safety profile in multiple types of cancer. However, only a subset of patients could benefit from PD-1 blockade therapy. Prognostic information including PD-1 ligand (PD-L1) expression, IFN-γ expression signature, tumor mutational burden, and microsatellite instability (MSI) have been evaluated for patients who are selected to receive immune checkpoint therapeutic treatment. Yet the relationship of those biomarkers in determining immune checkpoint therapy is largely unknown.MethodsImmune-profiles of MSI subtype colon cancer were identified from integrating published MSI associated gene expression data. The enriched pathways and transcription factors were analyzed by GSEA assay. The infiltrations of immune cell types into MSI subtype colon cancer tissues were determined by CIBESORT assay.ResultsIn the MSI subtype colon cancer patients, PD-L1, IFN-γ and IFN-γ associated genes are highly expressed. And all those genes are favorable effects in colon cancer progress. In addition, we find that Wnt-β-catenin and TGFβ signaling pathways which are two important factors inhibiting PD-1 checkpoint blockade therapy are negatively related with MSI status. We also identify that the immune-profiles in MSI subtype colon cancer are contributed by M1 macrophage infiltration in the tumor environment.ConclusionsOur results provide the detailed underlying mechanisms of MSI subtype cancer patients are sensitive to PD-1 checkpoint blockade.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Clinicopathological and biomolecular characteristics of stage IIB/IIC and stage IIIA colon cancer: Insight into the survival paradox.

A survival paradox of stage IIB/IIC and IIIA colon cancer has been consistently observed throughout revisions of the TNM system. This study aimed to understand this paradox with clinicopathological and molecular differences. Clinicopathological characteristics of patients with pathologically confirmed stage IIB/IIC or IIIA colon cancer were retrospectively reviewed from a database. Publicly available molecular data were retrieved, and intrinsic subtypes were identified and subjected to gene sets enrichment analysis (GSEA). Among the 159 patients included in the clinicopathological analysis, those at stage IIB/IIC had worse 3-year disease-free and overall survival than those at stage IIIA (59.3% vs 91.7%, P < 0.001 and 82.7% vs 98.5%, P < 0.001, respectively), even after adjusting for confounding factors. Data of 95 patients were retrieved from public databases, demonstrating a higher frequency of the microsatellite instable subtype in stage IIB/IIC. The consensus molecular subtype distribution pattern differed between the groups. The GSEA further suggested the protumor inflammatory reaction might be more prominent in stage IIB/IIC. The survival paradox in colon cancer was confirmed and appears to be a multifactorial phenomenon not attributed to a single clinicopathologic factor. However, the greater molecular heterogeneity in stage IIB/IIC could contribute to the poor prognosis.

Impact of adjuvant treatment according to gastric cancer molecular subtypes.

e15513 Background: The four subtypes of gastric adenocarcinoma (GC) identified by the Cancer Genome Atlas project (TCGA) have different molecular signatures and prognosis. Several centers have tried to classify GC using immunohistochemistry (IHC) and in situ hybridization (ISH), examining the tumors according to Epstein–Barr virus (EBV) status, microsatellite instability (MSI), aberrant E-cadherin expression and TP53 status. Here we aim to verify the impact of adjuvant/perioperative chemotherapy (ACT/PCT) or adjuvant chemoradiation (CRT) according to the molecular subtypes profile. Methods: We retrospectively reviewed all GC patients who underwent gastrectomy and D2-lymphadenectomy at our institution from a prospective collected medical database. Deficient DNA mismatch repair (dMMR), E-cadherin and p53 were evaluated by IHC for determining the MSI, genomically stable (GS) and chromosomal instability (CIN, with and without p53 aberrant) subtypes, respectively. EBV positivity was detected by ISH. Results: Among the 178 stage II/III patients included, 67 had surgery alone, 47 received ACT/PCT and 64 CRT. 16 had aberrant E-cadherin (GS, 9%), 33 dMMR (MSI, 18.5%), 74 aberrant p53 expression (CIN p53-aberrant, 41.6%), 104 normal p53 expression (CIN p53-normal, 58.4%) and 18 EBV-positivity (EBV, 10.1%). Two or more altered status were present in GC of 16 patients. When analyzed independently, Kaplan-Meier survival analysis showed that EBV, dMMR, CIN p53-normal and GS subtypes did not obtain any benefit of ACT/PCT or CRT in disease free survival (DFS) (p = 0.71; p = 0.33; p = 0.41; p = 0.21, respectively). Meantime, those treatments impact positively in DFS for EBV-negative, proficient MMR and non-GS (p = 0.01; p = 0.007; p = 0.01). CIN subtype with p53 aberrant obtained most benefit for ACT/PCT or CRT (p &lt; 0.001). Conclusions: In accordance with other studies we achieved no benefit for adjuvant chemotherapy in patients with EBV, dMMR and GS GC subtypes. Patients with p53 aberrant expression had greater benefit for ACT/PCT or CRT. This simple method of classification can potentially help to tailor adjuvant treatment.