Pattern of placental alkaline phosphatase (PLAP) expression in human tumors: a tissue microarray study on 12,381 tumors

Placental alkaline phosphatase (PLAP) is commonly expressed at high levels in testicular germ cell tumors. PLAP immunohistochemistry (IHC) is thus often used to confirm this diagnosis, especially in cases of putative metastasis. However, other tumors can also express PLAP. To comprehensively determine PLAP expression in normal and tumor tissue, a tissue microarray containing 16,166 samples from 131 different tumor types and subtypes as well as 608 samples from 76 different normal tissue types was analyzed by IHC. Moderate to strong PLAP positivity was found in 27 (21%) of 131 different tumor types including seminoma (96%), embryonal carcinoma (85%), and yolk sac tumors of the testis (56%); endometrioid carcinoma of the endometrium (28%) and the ovary (20%); gastric adenocarcinoma (22%); serous carcinoma (not otherwise specified) of the ovary (17%) and the uterus (11%); adenocarcinoma of the ampulla of Vater (15%); carcinosarcoma of the ovary (11%) and the uterus (8%); esophageal adenocarcinoma (10%); invasive urothelial carcinoma (4%); cholangiocarcinoma (2%); and adenocarcinoma of the lung (1%). Low‐level PLAP immunostaining, often involving only a small fraction of tumor cells, was seen in 21 additional tumor entities. The clinical significance of PLAP expression may vary between tumor types as high PLAP expression was linked to advanced pathological tumor stage (p = 0.0086), nodal metastasis (p = 0.0085), and lymphatic (p = 0.0007) and blood vessel invasion (p = 0.0222) in colorectal cancer, but to low pathological tumor stage in endometrial cancer (p = 0.0043). In conclusion, our data identify several tumor entities that can show PLAP expression at comparable levels to testicular germ cell tumors. These tumor entities need to be considered in cases of PLAP‐positive metastasis. Low‐level PLAP expression can be found in various other tumor entities and should generally not be viewed as a strong argument for germ cell neoplasia.

DOG1 is commonly expressed in pancreatic adenocarcinoma but unrelated to cancer aggressiveness

BACKGROUND

DOG1 (ANO1; TMEM16A) is a voltage-gated calcium-activated chloride and bicarbonate channel. DOG1 is physiologically expressed in Cajal cells, where it plays an important role in regulating intestinal motility and its expression is a diagnostic hallmark of gastrointestinal stromal tumors (GIST). Data on a possible role of DOG1 in pancreatic cancer are rare and controversial. The aim of our study was to clarify the prevalence of DOG1 expression in pancreatic cancer and to study its association with parameters of cancer aggressiveness.

METHODS

DOG1 expression was analyzed by immunohistochemistry in 599 pancreatic cancers in a tissue microarray format and in 12 cases of pancreatitis on large tissue sections.

RESULTS

DOG1 expression was always absent in normal pancreas but a focal weak expression was seen in four of 12 cases of pancreatitis. DOG1 expression was, however, common in pancreatic cancer. Membranous and cytoplasmic DOG1 expression in tumor cells was highest in pancreatic ductal adenocarcinomas (61% of 444 interpretable cases), followed by cancers of the ampulla Vateri (43% of 51 interpretable cases), and absent in 6 acinus cell carcinomas. DOG1 expression in tumor associated stroma cells was seen in 76 of 444 (17%) pancreatic ductal adenocarcinomas and in seven of 51 (14%) cancers of the ampulla Vateri. Both tumoral and stromal DOG1 expression were unrelated to tumor stage, grade, lymph node and distant metastasis, mismatch repair protein deficiency and the density of CD8 positive cytotoxic T-lymphocytes in the subgroups of ductal adenocarcinomas and cancers of ampulla Vateri. Overall, the results of our study indicate that DOG1 may represent a potential biomarker for pancreatic cancer diagnosis and a putative therapeutic target in pancreatic cancer. However, DOG1 expression is unrelated to pancreatic cancer aggressiveness.

Abstract 2775: PD-L1 expression in human tumors: a tissue microarray study on 5,561 tissue samples and 87 tumor types

The programmed death protein 1 (PD-1) and his ligand PD-L1 are frequently expressed in human cancers and immune checkpoint inhibitor therapies targeting the PD1/PD-L1 pathway are increasingly employed in a growing number of tumor types. However, a unanimous picture on PD-L1 expression in cancer cells and immune cells in various cancer types are so far lacking. In this study we analyzed PD-L1 expression in 5,561 tumor samples by immunohistochemistry in a highly standardized way to define the relative importance of PD-L1 expression and its relationship with tumor infiltrating CD8 positive lymphocytes across 87 human tumor types and subtypes. At a cut-off level of 10% positive tumor cells, PD-L1 positivity was seen in 62 of 87 (71%) tumor types. More than 50% PD-L1 positive cases were found in 7 (8%) tumor types, including thymoma (100%), Hodgkin lymphoma (93%), anaplastic thyroid carcinoma (67%), as well as squamous cell carcinomas of the penis (67%), cervix (65%), oral cavity (61%), and pharynx (50%). PD-L1 immunostaining in tumor cells was absent in 25 (29%) tumor types, including non-Hodgkin lymphomas, seminoma, endometrial malignant mixed Müllerian tumors, and mucinous carcinoma of the ovary. In immune cells, PD-L1 positivity was detectable in 79 (91%) tumor types, with the highest positivity rates in tumors of haemotopoetic and lymphoid tissues (75% to 100%), seminoma (85%), Warthin tumors of the parotid glands (83%), and Merkel cell carcinoma (82%). Immune cell PD-L1 positivity was absent in only 8 (9%) tumor types (e.g. chondosarcoma, pleomorphic adenoma of the salivary gland, and chromophobe renal cell carcinoma). PD-L1 positivity in tumor cells was significantly correlated with the number of intratumoral CD8 positive lymphocytes across all tumor types as well as in the separate analyses of several individual tumor types, such as basal cell carcinoma (p<0.0001), chondrosarcoma (p=0.0013), gastrointestinal stromal tumors (p=0.0028), and adrenal cortical carcinoma (p=0.0001). In summary, these data provide a ranking list of tumors according to their PD-L1 positivity rate. The strong association with the frequency of CD8 positive lymphocytes supports the concept, that PD-L1 expression in tumor cells represent a mechanism of highly immunogenic tumors to enable immune evasion.

Citation Format: Katharina Möller, Ronald Simon, Martina Kluth, Guido Sauter, Claudia Hube-Magg, Christoph Fraune, Niclas Blessin, Maximilian Lennartz, Doris Höflmayer, Sarah Minner, Eike Burandt, Sören Weidemann, Andreas Luebke. PD-L1 expression in human tumors: a tissue microarray study on 5,561 tissue samples and 87 tumor types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2775.

Abstract 2773: Deep profiling of the PD-1/PD-L1 pathway in 10000 cancers revealed changes in the immune cell composition between cancer entities

Immune checkpoint inhibitor (CPI) therapies targeting the PD-1/PD-L1 pathway have shown remarkable results in a rising number of different tumor entities. The likelihood of a positive response rate to CPIs depends - amongst other factors - on the PD-L1 expression level in tumor cells and tumor infiltrating immune cells. PD-L1 expression on different cell types is known to impact both the function and the composition of immune cells in the tumor microenvironment. However, this process is not fully understood. To study the impact of PD-L1 expression on the intratumoral immune environment, a multiplex fluorescence immunohistochemistry approach was used enabling the simultaneous analysis of 15 different antibodies on a set of tissue microarrays containing samples from more than 10000 neoplasms from more than 100 different tumor types and subtypes. Image analysis was performed using a U-net deep learning algorithm for cell detection and the “R” software package for statistical analysis. PD-L1 expression was measured on tumor cells (AE1/AE3+), subsets of macrophages (CD68+CD163+/CD68+iNOS+) and dendritic cells (CD11c+). To address the complexity of the tumor microenvironment, PD-1 expression was measured on B-cells (CD20+) and T-cell subsets, including cytotoxic T-cells (CD3+CD8+), T-helper cells (CD3+CD4+), regulatory T-cells (CD3+CD4+FOXP3+) and their memory (CD45RO+), activated (CD7-) or expanding (ki67+) phenotypes. Although PD-L1 expression varied significantly between cell types, patients and different tumor entities, the number of PD-1+ T-cells was consistently linked to PD-L1 expression. Combined analysis of cell densities, expression patterns, intensity measurements, interaction and distance analysis between immune cells and tumor cells revealed distinct changes in the immune cell infiltration pattern linked to PD-L1 expression. Previously uncharacterized immune cell-composition dynamics in clustered tumor phenotypes, according to the PD-L1 expression, were detected. This included significant associations between PD-L1+ tumor cells and PD-L1+ antigen-presenting cells and various PD-1+ T-cell subsets. In conclusion, deep profiling of 15 biomarkers in 10 000 cancers revealed complex differences in the composition of tumor infiltrating immune cells depending on the PD-L1 expression level of tumor cells and the mononuclear phagocyte system.

Citation Format: Niclas Christian Blessin, Cheng Yang, Jonas Raedler, Julia Ebner, Tim Mandelkow, Ronald Simon, Christoph Fraune, Maximilian Lennartz, Andreas M. Luebke, Sarah Minner, Eike Burandt, Doris Höflmayer, Guido Sauter, Katharina Möller, Sören A Weidemann. Deep profiling of the PD-1/PD-L1 pathway in 10000 cancers revealed changes in the immune cell composition between cancer entities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2773.

Abstract 2735: Clinical significance of CD4+CD7−helper T-cells and tumoral CD7 expression in colorectal cancer

CD7 is a transmembrane costimulatory glycoprotein and a member of the immunoglobulin supergene family, which is present on all thymocytes, most mature peripheral blood T-cells, and on natural killer (NK) cells. Studies indicate that the number of CD7 negative (CD7−) T-cells increases with age and in diseases such as chronic inflammation and in T-cell malignancies. To better understand the clinical relevance of CD7 expression in colon cancers and their immune microenvironment, tissue microarrays containing 1719 colorectal cancers were analyzed for CD3, CD4, CD8 and CD7 by multiplex fluorescence immunohistochemistry. Image analysis was performed using a U-net deep learning algorithm for cell detection and the “R” software package for statistical analysis. The density of CD3+CD4+ T-cells ranged from 0 to 8483 cells/mm2 (mean 504±686 cells/mm2) and the density of CD3+CD8+ T-cells ranged from 0 to 1386 cells/mm2 (mean 86±129 cells/mm2) in colorectal cancer. A high density of both, CD3+CD4+ helper T-cells and of CD3+CD8+ cytotoxic T-cells were associated with favorable tumor parameters, such as low tumor stage (p≤0.0004 each), negative nodal stage (p<0.0001 each) or absence of lymphatic vessel invasion (p≤0.0002 each) and high PD-L1 expression in immune cells (p<0.0001 each). In addition, a high density of CD3+CD8+ cytotoxic T-cells was linked to microsatellite instability (p<0.0001) and PD-L1 expression on tumor cells.The average fraction of T-cells lacking CD7 was 22% for CD3+CD4+ T-cells and 1% for CD3+CD8+ T-cells. A low fraction of CD3+CD4+CD7− T-cells was linked to low pT stage (p<0.0001) and microsatellite instability (p=0,0118) and tumor cell PD-L1 expression (p=0.0319) while the fraction of CD3+CD8+CD7− T-cells was unrelated to clinico-pathological parameters. Unequivocal membranous CD7 expression in cancer cells was found in 14 (0.8%) of cases and was significantly linked to lymphatic vessel invasion (p=0.0057) and perineural invasion (p=0.0045).In conclusion, the significant association of the fraction of CD3+CD4+CD7− T helper -cells with favorable clinicopathological features may suggest a clinically relevant role of this cell type. The rare CD7 positive colorectal cancers may potentially benefit from anti-CD7 therapies that are currently considered for T-cell neoplasias.

Citation Format: Niclas Christian Blessin, Cheng Yang, Maximilian Lennartz, Katharina Möller, Tim Mandelkow, Ronald Simon, Guido Sauter, Christoph Fraune, Doris Höflmayer, Sarah Minner, Eike Burandt, Sören A Weidemann, Andreas M Luebke. Clinical significance of CD4+CD7−helper T-cells and tumoral CD7 expression in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2735.

Diagnostic and prognostic impact of cytokeratin 19 expression analysis in human tumors: a tissue microarray study of 13,172 tumors

To evaluate cytokeratin 19 (CK19) expression in normal and cancerous tissues, 15,977 samples from 122 tumor types and 608 samples of 76 normal tissue types were analyzed by immunohistochemistry (IHC). In normal tissues, CK19 expression occurred in epithelial cells of most glandular organs but was strictly limited to the basal cell layer of nonkeratinizing squamous epithelium and absent in the skin. CK19 expression in ≥90% of cases was seen in 34% of the tumor entities including the adenocarcinomas of the pancreas (99.4%), colorectum (99.8%), esophagus (98.7%), and stomach (97.7%), as well as breast cancer (90.0%-100%), high-grade serous (99.1%) or endometrioid (97.8%) ovarian cancer, and urothelial carcinoma (92.6%-100%). A low CK19 positivity rate (0.1-10%) was seen in 5 of 122 tumor entities including hepatocellular carcinoma and seminoma. A comparison of tumor versus normal tissue findings demonstrated that upregulation and downregulation of CK19 can occur in cancer and that both alterations can be linked to unfavorable phenotypes. CK19 downregulation was linked to high grade (p = 0.0017) and loss of estrogen receptor- and progesterone receptor-expression (p < 0.0001 each) in invasive breast carcinoma of no special type. CK19 upregulation was linked to nodal metastases in neuroendocrine tumors and papillary thyroid carcinomas (p < 0.05 each) and to poor grade in clear cell renal cell carcinoma (p < 0.05). CK19 upregulation was particularly common in squamous cell carcinomas. We concluded that CK19 IHC might separate primary liver cell carcinoma from liver metastases, seminoma from other testicular tumors, and helps in the detection of early neoplastic transformation in squamous epithelium.

E-Cadherin expression in human tumors: a tissue microarray study on 10,851 tumors

BACKGROUND

The E-Cadherin gene (CDH1, Cadherin 1), located at 16q22.1 encodes for a calcium-dependent membranous glycoprotein with an important role in cellular adhesion and polarity maintenance.

METHODS

To systematically determine E-Cadherin protein expression in normal and cancerous tissues, 14,637 tumor samples from 112 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry in a tissue microarray format.

RESULTS

E-Cadherin was strongly expressed in normal epithelial cells of most organs. From 77 tumor entities derived from cell types normally positive for E-Cadherin, 35 (45.5%) retained at least a weak E-Cadherin immunostaining in ≥99% of cases and 61 (79.2%) in ≥90% of cases. Tumors with the highest rates of E-Cadherin loss included Merkel cell carcinoma, anaplastic thyroid carcinoma, lobular carcinoma of the breast, and sarcomatoid and small cell neuroendocrine carcinomas of the urinary bladder. Reduced E-Cadherin expression was linked to higher grade (p = 0.0009), triple negative receptor status (p = 0.0336), and poor prognosis (p = 0.0466) in invasive breast carcinoma of no special type, triple negative receptor status in lobular carcinoma of the breast (p = 0.0454), advanced pT stage (p = 0.0047) and lymph node metastasis in colorectal cancer (p < 0.0001), and was more common in recurrent than in primary prostate cancer (p < 0.0001). Of 29 tumor entities derived from E-Cadherin negative normal tissues, a weak to strong E-Cadherin staining could be detected in at least 10% of cases in 15 different tumor entities (51.7%). Tumors with the highest frequency of E-Cadherin upregulation included various subtypes of testicular germ cell tumors and renal cell carcinomas (RCC). E-Cadherin upregulation was more commonly seen in malignant than in benign soft tissue tumors (p = 0.0104) and was associated with advanced tumor stage (p = 0.0276) and higher grade (p = 0.0035) in clear cell RCC, and linked to advanced tumor stage (p = 0.0424) and poor prognosis in papillary RCC (p ≤ 0.05).

CONCLUSION

E-Cadherin is consistently expressed in various epithelial cancers. Down-regulation or loss of E-Cadherin expression in cancers arising from E-Cadherin positive tissues as well as E-Cadherin neo-expression in cancers arising from E-Cadherin negative tissues is linked to cancer progression and may reflect tumor dedifferentiation.

Prevalence of proliferating CD8+ cells in normal lymphatic tissues, inflammation and cancer

CD8⁺ cytotoxic T-lymphocytes are essential components of the anti-tumor immunity. To better understand the expansion of CD8⁺ T-cells we used multiplex fluorescence immunohistochemistry to study Ki67⁺CD8⁺ cells in normal lymphoid tissues, selected inflammatory diseases and cancers in 41 large sections/ microenvironment tissue microarrays (TMAs) as well as 765 samples in a conventional TMA format. The evaluation of more than 20 different compartments of normal lymphoid tissues revealed that the percentage of proliferating (ki67⁺) CD8⁺ cells did commonly not exceed 3%. In inflammations, the percentage of Ki67⁺CD8⁺ cells was more variable and higher compared to normal tissues. In cancers, the percentage of Ki67⁺CD8⁺ cells was higher in the tumor center than at the invasive margin. In the tumor center of 765 colorectal cancers, the density of Ki67⁺CD8⁺ cells and the percentage of proliferating CD8⁺ cytotoxic T-cells was significantly associated with microsatellite instability (p<0.0001), pT (p<0.0002) and pN category (p<0.0098). In summary, these data show that the percentage of Ki67⁺CD8⁺ cells is usually at a baseline proliferation rate below 3% in healthy secondary lymphoid organs. This rate is often markedly higher in inflammatory and neoplastic diseases compared to normal tissues. The striking link with unfavorable tumor features in colorectal cancer suggest a potential clinical utility of assessing the percentage of Ki67⁺CD8⁺ cells to predict patients outcome.

Napsin A Expression in Human Tumors and Normal Tissues

Background: Novel aspartic proteinase of the pepsin family A (Napsin A, TAO1/TAO2) is a functional aspartic proteinase which is involved in the maturation of prosurfactant protein B in type II pneumocytes and the lysosomal protein catabolism in renal cells. Napsin A is highly expressed in adenocarcinomas of the lung and is thus commonly used to affirm this diagnosis. However, studies have shown that other tumors can also express Napsin A.

Methods: To comprehensively determine Napsin A expression in normal and tumor tissue, 11,957 samples from 115 different tumor types and subtypes as well as 500 samples of 76 different normal tissue types were evaluable by immunohistochemistry on tissue microarrays.

Results: Napsin A expression was present in 16 different tumor types. Adenocarcinoma of the lung (85.6%), clear cell adenocarcinoma of the ovary (71.7%), clear cell adenocarcinoma of the endometrium (42.8%), papillary renal cell carcinoma (40.2%), clear cell (tubulo) papillary renal cell carcinoma (16.7%), endometrial serous carcinoma (9.3%), papillary thyroid carcinoma (9.3%) and clear cell renal cell carcinoma (8.2%) were among the tumors with the highest prevalence of Napsin A positivity. In papillary and clear cell renal cell carcinoma, reduced Napsin A expression was linked to adverse clinic-pathological features (p ≤ 0.03).

Conclusion: This methodical approach enabled us to identify a ranking order of tumors according to their relative prevalence of Napsin A expression. The data also show that loss of Napsin A is linked to tumor dedifferentiation in renal cell carcinomas.

Prognostic role of proliferating CD8+ cytotoxic Tcells in human cancers

PURPOSE

Expansion of CD8⁺ cytotoxic Tlymphocytes is a prerequisite for anti-cancer immune activity and has gained interest in the era of immune checkpoint therapy.

METHODS

To understand the CD8⁺ T cell dynamics in the tumor microenvironment, we used multiplex fluorescence immunohistochemistry to quantitate CD8⁺ proliferation (Ki67 co-expression) in tissue microarrays from 1107 colorectal, 642 renal cell, 1066 breast, 375 ovarian, 451 pancreatic and 347 gastric cancer samples.

RESULTS

The density and the percentage of proliferating (Ki67⁺) CD8⁺ T cells were both highly variable between tumor types as well as between patients with the same tumor type. Elevated density and percentage of proliferating CD8⁺ cytotoxic T cells were significantly associated with favorable tumor parameters such as low tumor stage, negative nodal stage (p ≤ 0.0041 each), prolonged overall survival (p ≤ 0.0028 each) and an inflamed immune phenotype (p = 0.0025) in colorectal cancer and, in contrast, linked to high tumor stage, advanced ISUP/Fuhrman/Thoenes grading (each p ≤ 0.003), shorter overall survival (p ≤ 0.0330 each) and an immune inflamed phenotype (p = 0.0094) in renal cell cancer. In breast, ovarian, pancreatic and gastric cancer the role of (Ki67⁺)CD8⁺ Tcells was not linked to clinicopathological data.

CONCLUSION

Our data demonstrate a tumor type dependent prognostic impact of proliferating (Ki67⁺)CD8⁺ Tcells and an inverse impact in colorectal and renal cell cancer.

Tumor cell PD-L1 expression is a strong predictor of unfavorable prognosis in immune checkpoint therapy-naive clear cell renal cell cancer

BACKGROUND

PD-L1 expression predicts response to immune checkpoint inhibitors in renal cell carcinomas (RCC), but has also been suggested to be linked to poor patient outcome.

METHODS

We analyzed PD-L1 in > 1400 RCC in a tissue microarray format by immunohistochemistry. Results were compared with histological tumor type, parameters of cancer aggressiveness, and intratumoral CD8⁺ cytotoxic cells.

RESULT

At a cut-off level of 5% PD-L1 positive tumor cells, PD-L1 positivity was seen in 6.3% of 633 clear cell RCC (ccRCC), 18.2% of 165 papillary RCC, 18.8% of 64 chromophobe RCC, and 41.7% of 103 oncocytomas. In ccRCC, PD-L1 positivity was significantly linked to high ISUP (p < 0.0001), Fuhrman (p < 0.0001), Thoenes grade (p < 0.0001), distant metastasis (p = 0.0042), short recurrence-free (p < 0.0001), and overall survival (p = 0.0002). Intratumoral CD8⁺ lymphocytes were more frequent in PD-L1 positive (1055 ± 109) than in PD-L1 negative ccRCC (407 ± 28; p < 0.0001). PD-L positive immune cells were seen in 8.2% of all RCC and 13.9% of papillary RCC. In ccRCC, PD-L1 positive immune cells were linked to high numbers of tumor-infiltrating CD8⁺ cells (p < 0.0001), high ISUP (p < 0.0001), Fuhrman (p = 0.0027), and Thoenes grade (p < 0.0001), and poor tumor-specific survival (p = 0.0280).

CONCLUSIONS

These data suggest that PD-L1 expression in highly immunogenic RCCs facilitates immune evasion and contributes to cancer aggressiveness.

Mismatch repair deficiency occurs very rarely in seminomas

Background

Dense tumor-associated lymphocyte infiltration is linked to mismatch repair (MMR) deficiency in colorectal and endometrial cancer. MMR deficiency is of high clinical importance as MMR deficient cancers tend to react favorably to treatment with immune checkpoint inhibitors. Strong lymphocytic infiltration is a morphological hallmark of seminomas. We thus asked whether seminomas may exhibit MMR deficiency at relevant frequency.

Methods

To screen for tumors with MMR deficiency, protein expression of MLH1, PMS2, MSH2, and MSH6 was analyzed by immunohistochemistry (IHC) on a tissue microarray (TMA) containing 574 seminomas.

Results

In total, 536 cases were evaluable resulting in 481 seminomas with unequivocally intact MMR protein expression. In 55 cancers, one or several IHC stains were equivocal and lacked detectable MMR protein in both tumor and stromal cells. Large section IHC analysis of all 55 equivocal cases demonstrated substantial staining issues due to improper fixation in 54 cases and identified one tumor with clear-cut MLH1 and PMS2 protein loss. This seminoma showed homogeneous loss of MLH1 and PMS2 in the entire tumor mass whereas minor adjacent foci of associated germ cell neoplasia in situ (GCNIS) were MMR intact. Polymerase chain reaction (PCR) analysis using the 5 microsatellite loci of the “Bethesda Panel” revealed instability in 1 of 4 interpretable loci (“MSI-low”) and additional instability of the complex tetra-penta repeat locus MYCL1 in this tumor.

Conclusions

In summary, one single seminoma with MMR deficiency, characterized by protein loss of MLH1 and PMS2, was identified among 536 interpretable seminomas (0.19%). MMR deficiency is not a relevant determinant of lymphocyte influx in seminoma.

Diagnostic and prognostic impact of cytokeratin 18 expression in human tumors: a tissue microarray study on 11,952 tumors

BACKGROUND

Cytokeratin 18 (CK18) is an intermediate filament protein of the cytokeratin acidic type I group and is primarily expressed in single-layered or "simple" epithelial tissues and carcinomas of different origin.

METHODS

To systematically determine CK18 expression in normal and cancerous tissues, 11,952 tumor samples from 115 different tumor types and subtypes (including carcinomas, mesenchymal and biphasic tumors) as well as 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry in a tissue microarray format.

RESULTS

CK18 was expressed in normal epithelial cells of most organs but absent in normal squamous epithelium. At least an occasional weak CK18 positivity was seen in 90 of 115 (78.3%) tumor types. Wide-spread CK18 positivity was seen in 37 (31.9%) of tumor entities, including adenocarcinomas of the lung, prostate, colon and pancreas as well as ovarian cancer. Tumor categories with variable CK18 immunostaining included cancer types arising from CK18 positive precursor cells but show CK18 downregulation in a fraction of cases, tumor types arising from CK18 negative precursor cells occasionally exhibiting CK18 neo-expression, tumors derived from normal tissues with variable CK18 expression, and tumors with a mixed differentiation. CK18 downregulation was for example seen in renal cell cancers and breast cancers, whereas CK18 neo-expression was found in squamous cell carcinomas of various origins. Down-regulation of CK18 in invasive breast carcinomas of no special type and clear cell renal cell carcinomas (ccRCC) was related to adverse tumor features in both tumors (p ≤ 0.0001) and poor patient prognosis in ccRCC (p = 0.0088). Up-regulation of CK18 in squamous cell carcinomas was linked to high grade and lymph node metastasis (p < 0.05). In summary, CK18 is consistently expressed in various epithelial cancers, especially adenocarcinomas.

CONCLUSIONS

Down-regulation or loss of CK18 expression in cancers arising from CK18 positive tissues as well as CK18 neo-expression in cancers originating from CK18 negative tissues is linked to cancer progression and may reflect tumor dedifferentiation.

Y-chromosome loss is frequent in male renal tumors

Background

Loss of the Y-chromosome is a common event in different tumor types but its prevalence and clinical relevance in renal cell tumors is still not understood.

Methods

It was the aim of this study to estimate the frequency and clinical relevance of Y-loss in kidney neoplasms. A cohort of 1,252 male renal tumors was analyzed in a tissue microarray format by fluorescence in-situ hybridization (FISH).

Results

Y-loss was found in 47% of tumors. The frequency of this alteration varied markedly between kidney tumor subtypes. Y-loss was most prevalent in papillary renal cell carcinoma (RCC) (77%) followed by chromophobe RCC (60%), oncocytoma (51%), clear cell RCC (39%) and clear cell (tubulo)papillary RCC (19%). Y-loss was linked to higher patient age and smaller tumor size at diagnosis. Mean age (95% CI) was 65 (64–66) years in patients with Y-loss in their tumor compared to 60 (58–61) years in patients without Y-loss (P<0.0001). Significant correlations between Y-loss and tumor phenotype were found only for papillary carcinomas (P=0.002), especially for type 1 (P=0.03).

Conclusions

Y-loss is present in different histologic subtypes of renal neoplasm. The highest frequency is in papillary RCC, where it may represent a potentially relevant prognostic biomarker suggesting favorable disease outcome.

Elevated MUC5AC expression is associated with mismatch repair deficiency and proximal tumor location but not with cancer progression in colon cancer

Mucin 5AC (MUC5AC) is a secreted gel-forming mucin expressed by several epithelia. In the colon, MUC5AC is expressed in scattered normal epithelial cells but can be abundant in colorectal cancers. To clarify the relationship of MUC5AC expression with parameters of tumor aggressiveness and mismatch repair deficiency (dMMR) in colorectal cancer, a tissue microarray containing 1812 colorectal cancers was analyzed by immunohistochemistry. MUC5AC expression was found in 261 (15.7%) of 1,667 analyzable colorectal cancers. MUC5AC expression strongly depended on the tumor location and gradually decreased from proximal (27.4% of cecum cancers) to distal (10.6% of rectal cancers; p < 0.0001). MUC5AC expression was also strongly linked to dMMR. dMMR was found in 21.3% of 169 cancers with MUC5AC positivity but in only 4.6% of 1051 cancers without detectable MUC5AC expression (p < 0.0001). A multivariate analysis showed that dMMR status and tumor localization predicted MUC5AC expression independently (p < 0.0001 each). MUC5AC expression was unrelated to pT and pN status. This also applied to the subgroups of 1136 proficient MMR (pMMR) and of 84 dMMR cancers. The results of our study show a strong association of MUC5AC expression with proximal and dMMR colorectal cancers. However, MUC5AC expression is unrelated to colon cancer aggressiveness.

MMR Deficiency is Homogeneous in Pancreatic Carcinoma and Associated with High Density of Cd8-Positive Lymphocytes

BACKGROUND

Microsatellite instability (MSI) has emerged as a predictive biomarker for immune checkpoint inhibitor therapy. Cancer heterogeneity represents a potential obstacle for the analysis of predicitive biomarkers. MSI has been reported in pancreatic cancer, but data on the possible extent of intratumoral heterogeneity are lacking.

METHODS

To study MSI heterogeneity in pancreatic cancer, a tissue microarray (TMA) comprising 597 tumors was screened by immunohistochemistry with antibodies for the mismatch repair (MMR) proteins MLH1, PMS2, MSH2, and MSH6.

RESULTS

In six suspicious cases, large section immunohistochemistry and microsatellite analysis (Bethesda panel) resulted in the identification of 4 (0.8%) validated MSI cases out of 480 interpretable pancreatic ductal adenocarcinomas. MSI was absent in 55 adenocarcinomas of the ampulla of Vater and 7 acinar cell carcinomas. MMR deficiency always involved MSH6 loss, in three cases with additional loss of MSH2 expression. Three cancers were MSI-high and one case with isolated MSH6 loss was MSS in PCR analysis. The analysis of 44 cancer-containing tumor blocks revealed that the loss of MMR protein expression was always homogeneous in affected tumors. Automated digital image analysis of CD8 immunostaining demonstrated markedly higher CD8 + tumor infiltrating lymphocytes in tumors with (mean = 685, median = 626) than without (mean = 227; median = 124) MMR deficiency (p < 0.0001), suggesting a role of MSI for immune response.

CONCLUSIONS

Our data suggest that MSI occurs early in a small subset of ductal adenocarcinomas of the pancreas and that immunohistochemical MMR analysis on limited biopsy or cytology material may be sufficient to estimate MMR status of the entire cancer mass.

Abstract 3854: Prevalence and prognostic role of FoxP3regulatory T lymphocytes in cancer: A tissue microarray study on &gt;20,000 cancers

Regulatory FoxP3+ lymphocytes function as suppressors of T-cell activity. The clinical impact of high FoxP3+ cell density in cancers is not fully understood, as some studies have linked high FoxP3+ cell density to good prognosis and others to poor prognosis in tumor cohorts with associated clinical data. While some data suggest that these variable data are due to biological differences between tumor entities, it is also possible that methodological differences have caused these discrepancies. This study was undertaken to analyze the density of FoxP3+ cells in various different cancer types by employing standardized methods. Tissue microarrays and large sections made from &gt;20,000 prostate, breast, colorectal, ovarian, pancreatic, bladder and stomach cancers were analyzed together with various normal and inflamed tissues by conventional brightfield FoxP3 immunohistochemistry. Samples were also analyzed by fluorescent multiplex immunohistochemistry to assess the fraction of Ki67+ FoxP3+ cells. Our results indeed suggested a variable role of FoxP3+ cells in different tumor types. High FoxP3+ density was linked to high Gleason grade (p=0.0003) and early biochemical recurrence (p&lt;0.0001) in 16923 prostate cancers, but to low tumor stage (p=0.027) and prolonged survival (p=0.0029) in 1341 breast cancers, and to low tumor stage (p&lt;0.0001) in 744 colorectal cancers. No significant associations were found to tumor phenotype in 549 ovarian, 574 pancreatic, 549 bladder and 346 stomach cancers. Multiplex fluorescence IHC analysis of FoxP3 and Ki67 revealed comparable fractions of proliferating FoxP3+ cells in healthy tissues (average 12.3%, range 5.8-18.5%) and inflammatory conditions (average 7.6%, range 2.6-17.2%). Interestingly, the rate of Ki67+FoxP3+ cells was markedly higher in 36 bladder cancers (average 14.2%, range 0-49.3%) suggesting active expansion of FOXP3+ cells in cancer.

Our data demonstrate an inverse prognostic impact of the FoxP3+ cell density in prostate and breast cancers. The increased proliferation rate of immune-regulatory FoxP3+ cells in some bladder cancer is interesting in the light of the variable response of these tumors to immune checkpoint inhibitors.

Citation Format: Tim Mandelkow, Elena Bady, Niclas Blessin, Claudia Hube-Magg, Ronald Simon, Guido Sauter, Christoph Fraune, Maximilian Lennartz, Katharin Möller, Sören Weidemann, Andreas Luebke, Doris Höflmayer. Prevalence and prognostic role of FoxP3regulatory T lymphocytes in cancer: A tissue microarray study on &gt;20,000 cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3854.

Abstract 4979: Prevalence of proliferating CD8+cells in normal lymphatic tissues, inflammation and cancer

Expansion of CD8+ cytotoxic T lymphocytes is a prerequisite for anti-cancer immune activity. In the era of immune checkpoint therapy, profound knowledge of the dynamics of CD8+ has regained considerable interest. However, systematically acquired data on CD8+ proliferation in large sets of normal and diseased tissues are sparse. Here, we applied multiplex fluorescence immunohistochemistry to conventional large sections and tissue microarrays in order to quantitate Ki67+CD8+ cells in &gt;20 different compartments of normal lymphoid tissues, 7 types of inflammatory diseases and 785 cancers. In most normal lymphoid tissues (tonsil, lymph node, thymus, Peyer's patches, spleen, colon, appendix) the percentage of Ki67+CD8+ cells typically did not exceed 3%. The percentage of Ki67+CD8+ cells was markedly higher (45%) in the immune-active cortex of the thymus, however. In inflammatory conditions (including Hashimoto thyroiditis, Lichen sclerosus of the penis, sarcoidosis, sialadenitis, IgG4 pancreatitis, Crohn's disease and eczema), the percentage of Ki67+CD8+ cells was much more variable and often sharply higher than in normal tissues. It ranged from 0.5% in one patient with sialadenitis to 19% in the intraepithelial compartment of Crohn's disease. In 765 colorectal cancers, the fraction of Ki67 positive CD8+ cytotoxic T cells ranged from 0 to 100% (mean: 20.6%). A high fraction of Ki67+CD8+ cells was significantly associated with microsatellite instability (p&lt;0.0001), low pT stage (p&lt;0.0001) and absence of nodal metastases (p=0.0005). In summary, our data show a variable increase of the fraction of proliferating CD8+ T cells in cancers and in inflammatory diseases as compared to healthy secondary lymphoid organs. The striking link with microsatellite instability and unfavorable tumor features suggest a potential clinical utility of assessing Ki67+CD8+ in colorectal cancer.

Citation Format: Maximilian Lennartz, Raed Abu-Hashem, Niclas Christian Blessin, Tim Mandelkow, Elena Bady, Ronald Simon, Claudia Hube-Magg, Guido Sauter, Christoph Fraune, Katharina Möller, Till S. Clauditz, Andreas M. Luebke, Franziska Büscheck. Prevalence of proliferating CD8+cells in normal lymphatic tissues, inflammation and cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4979.

Abstract 3870: Patterns of CD112R expression in normal lymphatic tissues, inflammation and cancer

CD112R is an inhibitory immune checkpoint receptor and a putative target for novel immune therapies, but little is known about its molecular epidemiology in healthy and diseased tissues. To study the prevalence and expression level of CD112R+ immune cells, we analyzed more than 200 samples of normal lymphatic, inflamed and cancerous tissues in a microenvironment tissue microarray format (4mm tissue spot diameter) and large sections using fluorescent multiplex immunohistochemistry.

CD112R expression was detected at variable intensity levels in 47% of CD8+ cytotoxic lymphocytes, 49% of CD4+ T helper cells, 30% of FOXP3+ regulatory T helper cells and in 25% of CD56+ natural killer cells, but no expression was seen in CD11c+ dendritic cells and CD68+ macrophages. All analyzed compartments across normal and diseased tissues showed a small subset (CD8: 9±18%, CD4: 5±15%, FOXP3: 2±5%) of immune cells with supramaximal CD112R expression. The highest fraction of cells with supramaximal CD112R expression was found in the subset of CD8+ cytotoxic T cells in the Peyer's patches of ileum (62%), the intergranuloma area of lymph node sarcoidosis (27%) and in ovarian cancer (37%). In cancerous tissues, the density and the fraction cytotoxic T cells with supramaximal CD112R expression was highly variable and ranged from 5% in bladder cancer to 3% in lung cancer and 36% in ovarian cancer. A high variability of the number of cells with supramaximal CD112R expression was also seen within every tumor entity.

In summary, our analysis shows that CD112R expression is abundant in various subsets of immune cells but identifies a small fraction of cells with exceedingly high CD112R levels. The widespread occurrence of CD112R+ cytotoxic T cells in the cancer microenvironment may suggest considerable opportunities for checkpoint inhibitors targeting CD112R.

Citation Format: Niclas Christian Blessin, Tim Mandelkow, Elena Bady, Claudia Hube-Magg, Guido Sauter, Ronald Simon, Christoph Fraune, Maximilian Lennartz, Sören A. Weidemann, Katharina Möller, Doris Höflmayer. Patterns of CD112R expression in normal lymphatic tissues, inflammation and cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3870.

Abstract 4970: Prognostic role of CD112R, PD-1 and Ki67 expression in CD8+cytotoxic T cells in colorectal cancer

Expression of inhibitory immune checkpoint receptors such as CD112R (Poliovirus Receptor-Related Immunoglobulin Domain-Containing Protein, PVRIG) and PD-1 on CD8+ lymphocytes are considered to indicate an “exhausted” stage of T cell activation while Ki67 protein expression in these cells is viewed as sign of activity or expansion. To assess the prognostic impact of the clinical impact of CD112R, PD-1, and Ki67 expression of CD8+ lymphocytes, expression of these proteins was analyzed by fluorescent multiplex immunohistochemistry on a tissue microarray containing 384 colorectal cancers with clinical follow-up data. An elevated fraction of CD8+Ki67+ cells was linked to the absence of nodal metastasis and longer survival in these tumors (p≤0.0039 each). CD112R and PD-1 expression was detected at variable intensity levels and were separately quantitated in both ki67+ (expanding) and Ki67 negative (non-expanding) CD8+ cytotoxic lymphocytes. Elevated PD-1 expression in CD8+ T cells was associated with an absence of nodal metastasis (p=0.004) and longer overall survival in all CD8+ cells (p=0.005). This association was more evident in the subset of expanding (p&lt;0.0001) than in non-expanding (p=0.034) cytotoxic T cells. Elevated CD112R expression level in CD8+ T cells were linked to a low tumor grade (p=0.048), absence of nodal metastasis (p=0.023) and a prolonged overall survival (p=0.041) but these associations were not retained in subgroups of either expanding or non-expanding CD8+ cells. Patients with an elevated fraction of CD8+ki67+CD112R+PD-1+cells exhibited a particularly good prognosis. In conclusion, our data reveal that “exhausted” CD112R+/ PD-1+CD8+ cytotoxic T lymphocytes are able to expand (ki67+). This observation in combination with the good prognosis of cancers with high number of expanding exhausted cells argues for retained cytotoxic activity of CD112R+/ PD-1+ CD8+ T lymphocytes.

Citation Format: Ronald Simon, Niclas Christian Blessin, Tim Mandelkow, Elena Bady, Claudia Hube-Magg, Guido Sauter, Maximilian Lennartz, Christoph Fraune, Sören A. Weidemann, Katharina Möller, Franziska Büscheck. Prognostic role of CD112R, PD-1 and Ki67 expression in CD8+cytotoxic T cells in colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4970.

Prevalence of CD8+ cytotoxic lymphocytes in human neoplasms

PURPOSE

Immune checkpoint inhibitors have recently been approved by the US FDA as first and/or second line therapy in a subset of cancer types. Recent evidence suggests that the quantity of tumor infiltrating lymphocytes (TILs) influences the likelihood of response to immune checkpoint inhibitors. Here, we set out to assess the density of CD8+ lymphocytes in a wide range of different cancer types and subtypes.

METHODS

The density of CD8+ lymphocytes was compared across different cancer types using tissue microarrays (TMAs) composed of up to 50 tumor samples each from 84 different cancer types and subtypes. In total 2652 cancers and 608 normal tissues were successfully analyzed by CD8 immunohistochemistry followed by automated image analysis of digitized slides.

RESULTS

We found that the median CD8+ lymphocyte counts ranged from 6 cells/mm2 in pleomorphic adenoma up to 1573 cells/mm2 in Hodgkin's lymphoma. The CD8 counts were generally lower in normal tissues compared to cancer tissues. Blood vessels of the spleen were the only non-lymphatic tissue staining positive for CD8. Tumor types approved for checkpoint inhibitor therapy, including malignant melanoma (81), muscle invasive urothelial carcinoma (119), small cell lung cancer (120), clear cell renal cell cancer (153), squamous cell carcinoma (189) and adenocarcinoma of the lung (328) as well as Hodgkin's lymphoma (1573) were all ranking among the upper half of our list. Comparably high CD8 densities (median cells/mm2) were also found in several rare and aggressive cancer types including Merkel cell carcinoma (70), angiosarcoma (95), anaplastic thyroid cancer (156) and embryonal carcinoma of the testis (186). In 73 of the 84 analyzed cancer types, the highly variable CD8 counts occasionally exceeded the average CD8 count of tumors for which checkpoint inhibitors have been approved.

CONCLUSION

These data support the concept that among most tumor types at least some individual cancers may benefit from treatment with immune checkpoint inhibitors.

Homogeneous MMR Deficiency Throughout the Entire Tumor Mass Occurs in a Subset of Colorectal Neuroendocrine Carcinomas

Neuroendocrine neoplasms comprise a heterogeneous group of tumors, categorized into neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) depending on tumor differentiation. NECs and high-grade NETs (G3) confer a poor prognosis, demanding novel treatment strategies such as immune checkpoint inhibition in tumors with microsatellite instability (MSI). To study any possible intratumoral heterogeneity of MSI, a tissue microarray (TMA) containing 199 NETs and 40 NECs was constructed to screen for MSI using immunohistochemistry (IHC) for the mismatch repair (MMR) proteins MLH1, PMS2, MSH2, and MSH6. Four cases suspicious for MSI were identified. Validation of MSI by repeated IHC on large sections and polymerase chain reaction (PCR)-based analysis using the "Bethesda Panel" confirmed MSI in 3 cecal NECs. One pancreatic NET G3 with MSI-compatible TMA results was MMR intact on large section IHC and microsatellite stable (MSS). The remaining 235 tumors exhibited intact MMR. Protein loss of MLH1/PMS2 was found in two and MSH6 loss in one cancer with MSI. Large section IHC on all available tumor-containing tissue blocks in NECs with MSI did not identify aberrant tumor areas with intact MMR. Our data indicate that MSI is common in colorectal NECs (3 out of 10) but highly infrequent in neuroendocrine neoplasms from many other sites. The lack of intratumoral heterogeneity of MMR deficiency suggests early development of MSI during tumorigenesis in a subset of colorectal NECs and indicates that microsatellite status obtained from small biopsies may be representative for the entire cancer mass.

Upregulation of the heterogeneous nuclear ribonucleoprotein hnRNPA1 is an independent predictor of early biochemical recurrence in TMPRSS2:ERG fusion-negative prostate cancers

Heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) is a ubiquitous RNA splicing factor that is overexpressed and prognostically relevant in various human cancer types. To study the impact of hnRNPA1 expression in prostate cancer, we analyzed a tissue microarray containing 17,747 clinical prostate cancer specimens by immunohistochemistry. hnRNPA1 was expressed in normal prostate glandular cells but often overexpressed in cancer cells. hnRNPA1 immunostaining was interpretable in 14,258 cancers and considered strong in 33.4%, moderate in 45.9%, weak in 15.3%, and negative in 5.4%. Moderate to strong hnRNPA1 immunostaining was strongly linked to adverse tumor features including high classical and quantitative Gleason score, lymph node metastasis, advanced tumor stage, positive surgical margin, and early biochemical recurrence (p < 0.0001 each). The prognostic impact of hnRNPA1 immunostaining was independent of established preoperatively or postoperatively available prognostic parameters (p < 0.0001). Subset analyses revealed that all these associations were strongly driven by the fraction of cancers lacking the TMPRSS2:ERG gene fusion. Comparison with other key molecular data that were earlier obtained on the same TMA showed that hnRNPA1 overexpression was linked to high levels of androgen receptor (AR) expression (p < 0.0001) as well as presence of 9 of 11 chromosomal deletions (p < 0.05 each). A strong association between hnRNPA1 upregulation and tumor cell proliferation that was independent from the Gleason score supports a role for tumor cell aggressiveness. In conclusion, hnRNPA1 overexpression is an independent predictor of poor prognosis in ERG-negative prostate cancer. hnRNPA1 measurement, either alone or in combination, might provide prognostic information in ERG-negative prostate cancer.