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Multiplex fluorescence IHC (mfIHC) approaches were yet either limited to six markers or limited to a small tissue size that hampers translational studies on large tissue microarray cohorts. Here we have developed a BLEACH&STAIN mfIHC method that enabled the simultaneous analysis of 15 biomarkers (PD-L1, PD-1, CTLA-4, panCK, CD68, CD163, CD11c, iNOS, CD3, CD8, CD4, FOXP3, CD20, Ki67, and CD31) in 3,098 tumor samples from 44 different carcinoma entities within one week. To facilitate automated immune checkpoint quantification on tumor and immune cells and study its spatial interplay an artificial intelligence–based framework incorporating 17 different deep-learning systems was established. Unsupervised clustering showed that the three PD-L1 phenotypes (PD-L1+ tumor and immune cells, PD-L1+ immune cells, PD-L1−) were either inflamed or noninflamed. In inflamed PD-L1+patients, spatial analysis revealed that an elevated level of intratumoral M2 macrophages as well as CD11c+ dendritic cell (DC) infiltration (P < 0.001 each) was associated with a high CD3+ CD4± CD8± FOXP3± T-cell exclusion and a high PD-1 expression on T cells (P < 0.001 each). In breast cancer, the PD-L1 fluorescence intensity on tumor cells showed a significantly higher predictive performance for overall survival (OS; AUC, 0.72, P < 0.001) compared with the commonly used percentage of PD-L1+ tumor cells (AUC, 0.54). In conclusion, our deep-learning–based BLEACH&STAIN framework facilitates rapid and comprehensive assessment of more than 60 spatially orchestrated immune cell subpopulations and its prognostic relevance. Implications: The development of an easy-to-use high-throughput 15+1 multiplex fluorescence approach facilitates the in-depth understanding of the immune tumor microenvironment (TME) and enables to study the prognostic relevance of more than 130 immune cell subpopulations.

BACKGROUND: Programmed death ligand 1 (PD-L1) is the target of immune checkpoint inhibitor therapies in a growing number of tumor types, but a unanimous picture on PD-L1 expression across cancer types is lacking. MATERIALS AND METHODS: We analyzed immunohistochemical PD-L1 expression in 11,838 samples from 118 human tumor types and its relationship with tumor infiltrating CD8 positive lymphocytes. RESULTS: At a cut-off level of 10% positive tumor cells, PD-L1 positivity was seen in 85 of 118 (72%) tumor types, including thymoma (100% positive), Hodgkin’s lymphoma (93%), anaplastic thyroid carcinoma (76%), Kaposi sarcoma (71%), sarcomatoid urothelial carcinoma (71%), and squamous cell carcinoma of the penis (67%), cervix (65%), floor of the mouth (61%), the lung (53%), and pharynx (50%). In immune cells, PD-L1 positivity was detectable in 103 (87%) tumor types, including tumors of haematopoetic and lymphoid tissues (75% to 100%), Warthin tumors of the parotid glands (95%) and Merkel cell carcinoma (82%). 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 individual tumor types, including serous carcinoma of the ovary, invasive breast carcinoma of no special type, intestinal gastric adenocarcinoma, and liposarcoma (p< 0.0001 each). CONCLUSIONS: PD-L1 expression in tumor and inflammatory cells is found in a wide range of human tumor types. Higher rates of tumor infiltrating CD8 positive lymphocytes in PD-L1 positive than in PD-L1 negative cancers suggest that the antitumor immune response may trigger tumoral PD-L1 expression.

BACKGROUND Immune checkpoint-inhibitors targeting the PD-1/PD-L1 system are FDA approved in microsatellite instable (MSI) or mismatch repair deficient (dMMR) colorectal cancer (CRC). PD-L1 expression is tightly linked to features connected to immune checkpoint inhibitor response, but studies on large subsets of cancers analyzing the correlation between different status of MSI/dMMR, tumor infiltrating lymphocytes and PD-L1 expression are still lacking. METHODS More than 1800 CRC were analyzed for PD-L1 by immunohistochemistry in a tissue microarray format. Data were compared to MMR, the number of intratumoral CD8+ cytotoxic T-cells, and adverse clinico-pathological parameters. Different cutoff levels for defining PD-L1 positivity in tumor cells (1%, 5%, 10%, and 50%) yielded comparable results. RESULTS At a cutoff level of 5%, PD-L1 positivity was seen in 5.1% of tumors. PD-L1 was more often positive in dMMR (18.6%) than in MMR proficient (pMMR) cancers (4.1%; p

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

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.

Tripartite motif containing 24 (TRIM24) is a multifunctional protein involved in p53 degradation, chromatin binding, and transcriptional modulation of nuclear receptors. Emerging research has revealed that upregulation of TRIM24 in numerous tumor types is linked to poor prognosis, attributing an important role to TRIM24 in tumor biology. In order to better understand the role of TRIM24 in prostate cancer, we analyzed its immunohistochemical expression on a tissue microarray containing >17,000 prostate cancer specimens. TRIM24 immunostaining was detectable in 61% of 15,321 interpretable cancers, including low expression in 46% and high expression in 15% of cases. TRIM24 upregulation was associated with high Gleason grade, advanced pathologic tumor stage, lymph node metastasis, higher preoperative prostate-specific antigen level, increased cell proliferation as well as increased genomic instability, and predicted prognosis independent of clinicopathologic parameters available at the time of the initial biopsy (all P

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 p p

Deletion of chromosome 5q is common in prostate cancer and is linked to aggressive disease. Most previous studies focused on 5q21 where CHD1 is located, but deletion of mapping studies has identified a second deletion hotspot at 5q13. To clarify the prevalence and clinical relevance of 5q13 deletions and to determine the relative importance of 5q13 and 5q21 abnormalities, a tissue microarray containing samples from 12 427 prostate cancers was analyzed by fluorescence in situ hybridization. Deletion of 5q13 and 5q21 was found in 13.5% and 10%, respectively, of 7932 successfully analyzed cancers. Deletion was restricted to 5q13 in 49.4% and to 5q21 in 32.0% of cancers with a 5q deletion. Only 18.6% of 5q-deleted cancers had deletions of both loci. Both 5q13 and 5q21 deletions were significantly linked to advanced tumor stage, high Gleason grade, nodal metastasis and early biochemical recurrence (P < .005 each). Cancers with co-deletion of 5q13 and 5q21 had a worse prognosis than cancers with isolated 5q13 or 5q21 deletion (P = .0080). Comparison with TMPRSS2:ERG fusion status revealed that 5q21 deletions were tightly linked to ERG negativity (P < .0001) while 5q13 deletions were unrelated to the ERG status. In summary, 5q13 deletion and 5q21 deletion are common, but independent genomic alterations with different functional effects lead to aggressive prostate cancer.

B7-H3 is a member of the B7 superfamily of immune checkpoint molecules. B7-H3 up regulation has been linked to cancer development and progression in many tumors including prostate cancer. To clarify the potential utility of B7-H3 as a prognostic biomarker, B7-H3 expression was analyzed by immunohistochemistry in more than 17 000 prostate cancers. Normal prostatic glands were largely B7-H3 negative, while membranous B7-H3 immunostaining was seen in 47.0% of analyzed cancers. B7-H3 immunostaining was weak in 12.3%, moderate in 21.1% and strong in 13.5% of cases. High B7-H3 expression was associated with pT, Gleason score, lymph node metastasis, high Ki67 labeling index and early prostate-specific antigen recurrence (P < 0.0001 each). High B7-H3 expression was also linked to high androgen receptor expression and TMPRSS2:V-ets avian erythroblastosis virus E26 oncogene homolog (ERG) fusions (P < 0.0001 each). Multivariate analyses showed a strong independent prognostic impact of high B7-H3 expression in all cancers and in the ERG negative subgroup. Comparison with previously analyzed frequent chromosomal deletions revealed a close association with Phosphatase and Tensin Homolog deletions. Analysis of B7-H3, alone or in combination with other markers, might be of clinical utility, especially in the subgroup of ERG negative prostate cancers.

Secreted frizzled-related protein 4 (SFRP4) controls WNT signaling and is thought to play a role for tumor aggressiveness. Here, we analyzed a tissue microarray containing 11,152 prostate cancers with pathological, clinical and molecular data by immunohistochemistry. SFRP4 expression was higher in cancer than in non-neoplastic acinar cells. SFRP4 staining was seen in 64.9% of tumors and classified as weak in 33.2%, moderate in 23.9% and strong in 7.8% of cancers. SFRP4 overexpression was linked to advanced tumor stage, high classical/quantitative Gleason grade (p

The transcriptional coactivator YAP1 controls the balance between cell proliferation and apoptosis. YAP1 overexpression is linked to poor prognosis in many cancer types, yet its role in prostate cancer is unknown. Here, we applied YAP1 immunohistochemistry to a tissue microarray containing 17,747 clinical prostate cancer specimens. Cytoplasmic and nuclear YAP1 staining was seen in 81% and 63% of tumours. For both cytoplasmic and nuclear YAP1 staining, high levels were associated with advanced tumour stage, classical and quantitative Gleason grade, positive nodal stage, positive surgical margin, high KI67 labelling index, and early biochemical recurrence (p TMPRSS2:ERG fusion (p PTEN and 8p deletions (p

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

Altered expression of the carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) has been linked to adverse tumor features in various cancer types. To better understand the role of CEACAM1 in prostate cancer, we analyzed a tissue microarray containing tumor spots from 17,747 prostate cancer patients by means of immunohistochemistry. Normal prostate glands showed intense membranous CEACAM1 positivity. Immunostaining was interpretable in 13,625 cancers and was considered high in 28%, low in 43% and absent in 29% of tumors. Low and lost CEACAM1 expression was strongly linked to adverse tumor features including high classical and quantitative Gleason grade, lymph node metastasis, advanced tumor stage, positive surgical margin, a high number of genomic deletions and early biochemical recurrence (p < 0.0001 each). Subset analysis of molecularly defined cancer subsets revealed that these associations were strongest in V-ets avian erythroblastosis virus E26 oncogene homolog (ERG) fusion-positive cancers and that CEACAM1 loss was prognostic even in tumors harboring genomic deletions of the phosphatase and tensin homolog tumor suppressor (p < 0.0001). Multivariate analysis suggested that CEACAM1 analysis can provide independent prognostic information beyond established prognosis parameters at the stage of the initial biopsy when therapy decisions must be taken. In conclusion, loss of CEACAM1 expression predicts poor prognosis in prostate cancer and might provide clinically useful prognostic information particularly in cancers harboring the TMPRSS2:ERG fusion.

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.

Background TFAP2D is a transcription factor important for modulating gene expression in embryogenesis. Its expression and prognostic role in prostate cancer has not been evaluated. Methods Therefore, a tissue microarray containing 17,747 prostate cancer specimens with associated pathological, clinical, and molecular data was analyzed by immunohistochemistry to assess the role of TFAP2D. Results TFAP2D expression was typically increased in prostate cancer as compared to adjacent non-neoplastic glands. TFAP2D staining was considered negative in 24.3% and positive in 75.7% of 13,545 interpretable cancers. TFAP2D staining was significantly linked to advanced tumor stage, high classical and quantitative Gleason grade, lymph node metastasis, and a positive surgical margin (p ≤ 0.0045). TFAP2D positivity was more common in ERG fusion positive (88.7%) than in ERG negative cancers (66.8%; p TMPRSS2:ERG fusion revealed that associations with tumor phenotype and patient outcome were largely driven by the subset of ERG negative tumors. Multivariate analysis did not identify TFAP2D protein expression levels as a robust independent prognostic parameter. Positive TFAP2D immunostaining was significantly associated with 10 of 11 previously analyzed chromosomal deletions in ERG negative cancers (p ≤ 0.0244 each) indicating that elevated TFAP2D expression parallels genomic instability in prostate cancer. Conclusion These data demonstrate that TFAP2D protein overexpression is linked to prostate cancer progression and genomic instability in ERG negative prostate cancers.

Background: The composition and functional state of T-cell subpopulations can highly impact patient’s outcome and response to immune checkpoint therapy. However, only little is known about the spatial interplay of most rare T-cell subpopulations. Design: To assess the density, composition, degree of immune checkpoint expression, and spatial interplay of T-cell subpopulations in 5989 tumor samples from more than 100 tumor entities, two different types of tissue microarrays (0.6 mm and 4 mm in diameter) were stained with antibodies directed against CD3, CD4, CD8, FOXP3, T-bet, GATA3, RORyT, BCL6, FOXP3, CD56, CD45RA, CD45RO, TIM3, PD-1, CTLA-4 Granzym B, and Ki67 using our BLEACH&STAIN multiplex fluorescence immunohistochemistry approach. A deep learning-based framework comprising two different convolutional neuronal networks (U-Net and DeepLabv3+) was used for image analysis. Results: For identification and definition of immune cell subpopulations unsupervised X-shift clustering and 2D/3D t-distributed stochastic neighbor embedding (t-SNE) using the “Rtsne” package (Rtsne (RRID:SCR_016342)) were applied and revealed 102 T-cell subpopulations at certain functional state. Within these subpopulations, the well-characterized expression profiles were visually matched with single T-cell expression profiles and documented as digital images. This process resulted in 12 main T-cell subsets that were further subclassified according to their functional state (proliferation, immune checkpoint expression) and studied according to their spatial orchestration. Interestingly, the vast majority of T-cell subsets were found in all analyzed tumor entities. However, their spatial orchestration, immune checkpoint expression profile was highly variable between different tumor entities. Conclusion: This study provides a comprehensive overview of rare T-cells subpopulations and its spatial orchestration in more than 100 different tumor entities. Citation Format: Zhihao Huang, Elena Bady, Jan H. Müller, Tim Mandelkow, Magalie C. Lurati, Ronald Simon, Christian Bernreuther, Frank Jacobsen, Guido Sauter, Katharina Möller, Andreas Luebke, Andrea Hinsch, Till S. Clauditz, Eike Burandt, Niclas C. Blessin. Spatial T-cell atlas in more than 100 different tumor entities using BLEACH&STAIN. [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 5144.

Dysregulation of lipid metabolism is common in cancer. Lysophosphatidylcholine acyltransferase 1 (LPCAT1) has been implicated with various cancer types. Here we analyzed by immunohistochemistry its expression in 2,197 breast cancers. LPCAT1 staining was found in 97.8% of 1,774 interpretable tumors, including 48.1% with weak, 28.7% with moderate, and 14.4% with strong expression. The frequency of LPCAT1 positivity depended on the histological tumor type. Moderate or strong LPCAT1 positivity was more common in cancers of no special type (NST) (46.2%) than in lobular carcinomas (25.9%; p

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 p 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.

Mesothelin (MSLN) represents an attractive molecule for targeted cancer therapies. To identify tumors that might benefit from such therapies, tissue microarrays including 15,050 tumors from 122 different tumor types and 76 healthy organs were analyzed for MSLN expression by immunohistochemistry. Sixty-six (54%) tumor types showed at least occasional weak staining, including 50 (41%) tumor types with at least one strongly positive sample. Highest prevalence of MSLN positivity had ovarian carcinomas (serous 97%, clear cell 83%, endometrioid 77%, mucinous 71%, carcinosarcoma 65%), pancreatic adenocarcinoma (ductal 75%, ampullary 81%), endometrial carcinomas (clear cell 71%, serous 57%, carcinosarcoma 50%, endometrioid 45%), malignant mesothelioma (69%), and adenocarcinoma of the lung (55%). MSLN was rare in cancers of the breast (7% of 1138), kidney (7% of 807), thyroid gland (1% of 638), soft tissues (0.3% of 931), and prostate (0 of 481). High expression was linked to advanced pathological tumor (pT) stage (p &lt, 0.0001) and metastasis (p &lt, 0.0001) in 1619 colorectal adenocarcinomas, but unrelated to parameters of malignancy in 1072 breast-, 386 ovarian-, 174 lung-, 757 kidney-, 171 endometrial-, 373 gastric-, and 925 bladder carcinomas. In summary, numerous important cancer types with high-level MSLN expression might benefit from future anti-MSLN therapies, but MSLN’s prognostic relevance appears to be limited.

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 p p p = 0.0042), short recurrence-free (p p = 0.0002). Intratumoral CD8+ lymphocytes were more frequent in PD-L1 positive (1055 ± 109) than in PD-L1 negative ccRCC (407 ± 28; p + cells (p p p = 0.0027), and Thoenes grade (p p = 0.0280). Conclusions These data suggest that PD-L1 expression in highly immunogenic RCCs facilitates immune evasion and contributes to cancer aggressiveness.

Multiplex fluorescence immunohistochemistry (mfIHC) approaches were yet either limited to 6 markers or limited to a small (1.5cmx1.5cm) tissue size that hampers translational studies on large tissue microarray (TMA) cohorts. To be able to assess more marker in a large patient cohort, we have developed a BLEACH&STAIN multiplex fluorescence immunohistochemistry approach that enabled the simultaneous analysis of 15 biomarkers. To study the relationship of PD-L1 expression on multiple different cell types and the relationship with various lymphocyte subtypes, PD-L1, PD-1, CTLA-4, panCK, CD68, CD163, CD11c, iNOS, CD3, CD8, CD4, FOXP3, CD20, Ki67, and CD31 were analyzed in 3098 tumor samples from 44 different tumor types. An artificial intelligence-based framework - incorporating three different deep learning systems - for automated marker quantification on tumor as well as immune cells was further established to study the spatial interplay between PD-L1 expression and the composition of tumor infiltrating leucocytes (TILs). Comparing the automated deep learning-based PD-L1 quantification with conventional brightfield PD-L1 data revealed a high concordance in tumor cells (p Citation Format: Elena Bady, Katharina Möller, Tim Mandelkow, Ronald Simon, Maximilian Lennartz, Claudia Hube-Magg, Guido Sauter, Niclas C. Blessin. BLEACH&STAIN 15 marker multiplexed imaging in 3098 human carcinomas revealed six major PD-L1 driven immune phenotypes with distinct spatial orchestration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 597.

Background Epithelial splicing regulatory protein 1 (ESRP1) and 2 (ESRP2) regulate alternative splicing events of various pre-mRNAs. Some of these targets play a role in cancer-associated processes, including cytoskeleton reorganization and DNA-repair processes. This study was undertaken to estimate the impact of ESRP1 and ESRP2 alterations on prostate cancer patient prognosis. Methods A tissue microarray made from 17,747 individual cancer samples with comprehensive, pathological, clinical and molecular data was analyzed by immunohistochemistry for ESRP1 and ESRP2. Results Nuclear staining for ESRP1 was seen in 38.6% (36.0% low, 2.6% high) of 12,140 interpretable cancers and in 41.9% (36.4% low, 5.3% high) of 12,962 interpretable cancers for ESRP2. Nuclear protein expression was linked to advanced tumor stage, high Gleason score, presence of lymph node metastasis, early biochemical recurrence, and ERG-positive cancers (p Conclusions Our data show a striking link between nuclear ESRP expression and adverse features in prostate cancer and identifies expression of ESRP1 and/or ESRP2 as independent prognostic markers with a potential for routine application.

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 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.

Background Tumor protein 63 (p63) is a transcription factor of the p53 gene family involved in differentiation of several tissues including squamous epithelium. p63 immunohistochemistry is broadly used for tumor classification but published data on its expression in cancer is conflicting. Methods To comprehensively catalogue p63 expression, tissue microarrays (TMAs) containing 12,620 tissue samples from 115 tumor entities and 76 normal tissue types were analyzed. Results p63 expression was seen in various normal tissues including squamous epithelium and urothelium. At least occasional weak p63 positivity could be detected in 61 (53%) of 115 different tumor types. The frequencies of p63 positivity was highest in squamous cell carcinomas irrespective of their origin (96–100%), thymic tumors (100%), urothelial carcinomas (81–100%), basal type tumors such as basal cell carcinomas (100%), and various salivary gland neoplasias (81–100%). As a rule, p63 was mostly expressed in cancers derived from p63 positive normal tissues and mostly not detectable in tumors derived from p63 negative cancers. However, exceptions from this rule occurred. A positive p63 immunostaining in cancers derived from p63 negative tissues was unrelated to aggressive phenotype in 422 pancreatic cancers, 160 endometrium cancers and 374 ovarian cancers and might be caused by aberrant squamous differentiation or represent stem cell properties. In 355 gastric cancers, aberrant p63 expression occurred in 4% and was linked to lymph node metastasis (p = 0.0208). Loss of p63 in urothelial carcinomas - derived from p63 positive urothelium - was significantly linked to advanced stage, high grade (p p Conclusion The high prevalence of p63 expression in specific tumor types makes p63 immunohistochemistry a suitable diagnostic tool. Loss of p63 expression might constitute a feature of aggressive cancers.

Background 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. Materials and Methods Tissue microarrays and large sections made from >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. Results 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 Conclusions 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. Disclosure Information T. Mandelkow: None. E. Bady: None. N.C. Blessin: None. C. Hube-Magg: None. R. Simon: None. G. Sauter: None. C. Fraune: None. M. Lennartz: None. K. Moller: None. S.A. Weidemann: None. A.M. Luebke: None. D. Hoflmayer: None. F. Buscheck: None.

Background 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. Materials and Methods 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 (4 mm tissue spot diameter) and large sections using fluorescent multiplex immunohistochemistry. Results 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. Conclusions 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. Disclosure Information N.C. Blessin: None. T. Mandelkow: None. E. Bady: None. C. Hube-Magg: None. R. Simon: None. G. Sauter: None. C. Fraune: None. M. Lennartz: None. K. Moller: None. D. Hoflmayer: None. S.A. Weidemann: None.

Deletions of chromosome arm 13q belong to the most frequent molecular alterations in prostate cancer. To better understand the role of 13q deletion in prostate cancer we took advantage of our large prostate cancer tissue microarray comprising more than 12 000 cancer samples with full pathological and clinical follow-up data. Fluorescence in situ hybridization with probes for ENOX1 (13q14.11) and the retinoblastoma gene (RB1, 13q14.2) was employed. A 13q deletion was found in 21% of 7375 analyzable cancers. Deletions were always heterozygous and associated with high Gleason grade (P

Introduction: The quantification of PD-L1 (programmed cell death ligand 1) has been used to predict patient's survival, to characterize the tumor immune microenvironment, and to predict response to immune checkpoint therapies. However, a framework to assess the PD-L1 status with a high interobserver reproducibility on tumor cells and different types of immune cells has yet to be established. Methods: To study the impact of PD-L1 expression on the tumor immune microenvironment and patient outcome, a framework for fully automated PD-L1 quantification on tumor cells and immune cells was established and validated. Automated PD-L1 quantification was facilitated by incorporating three different deep learning steps for the analysis of more than 80 different neoplasms from more than 10'000 tumor specimens using a bleach & stain 15-marker multiplex fluorescence immunohistochemistry panel (i.e., PD-L1, PD-1, CTLA-4, panCK, CD68, CD163, CD11c, iNOS, CD3, CD8, CD4, FOXP3, CD20, Ki67, CD31). Clinicopathological parameter were available for more than 30 tumor entities and overall survival data were available for 1517 breast cancer specimens. Results: Comparing the automated deep-learning based PD-L1 quantification with conventional brightfield PD-L1 data revealed a high concordance in tumor cells (p Conclusion: In conclusion, multiplex immunofluorescence PD-L1 assessment provides cutoff-free/continuous PD-L1 data which are superior to the conventional percentage of PD-L1+ tumor cells and of high prognostic relevance. The combined analysis of spatial PD-L1/PD-1 data and more than 20 different immune cell subtypes of the immune tumor microenvironment revealed distinct PD-L1 immune phenotypes. Citation Format: Niclas C. Blessin, Elena Bady, Tim Mandelkow, Cheng Yang, Jonas B. Raedler, Ronald Simon, Christoph Fraune, Maximilian Lennartz, Sarah Minner, Eike Burandt, Doris Höflmayer, Guido Sauter, Katharina Möller, Sören A. Weidemann. Automated cell type specific PD-L1 quantification by artificial intelligence using high throughput bleach & stain 15-marker multiplex fluorescence immunohistochemistry in human cancers [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P068.

Background: Remodelling and spacing factor 1 (RSF1) is involved in the regulation of chromatin remodelling and represents a potential therapeutic target. High RSF1 expression has been linked to adverse tumour features in many cancer types, but its role in prostate cancer is uncertain. Methods: In this study, RSF1 expression was analysed by immunohistochemistry on a tissue microarray with 17,747 prostate cancers. Results: Nuclear RSF1 staining of 16,456 interpetable cancers was considered strong, moderate, weak and negative in 25.2%, 48.7%, 5.3% and 20.8% of cancers respectively. Positive RSF1 expression was associated with advanced tumour stage, high Gleason grade, lymph node metastasis (p p p p Conclusion: In summary, the results of our study identify RSF1 as an independent prognostic marker in prostate cancer with a particularly strong role in ERG negative cases.

Checkpoint kinase 2 (CHK2) is a serine-threonine kinase with a role in DNA repair, cell cycle arrest or apoptosis in response to DNA damage. Both reduced and increased CHK2 expression has been described in different tumour types with impact on patient prognosis. To evaluate prevalence and significance of altered CHK2 expression in prostate cancer, a tissue microarray containing 17,747 tumours was analysed by immunohistochemistry. Nuclear CHK2 immunostaining was absent or weak in benign prostate epithelium but often more prominent in cancers. CHK2 immunostaining was considered weak in 38.8%, moderate in 33.6% and strong in 11.2% of prostate cancers. High CHK2 expression was strongly associated with TMPRSS2:ERG fusions (p0.0001). Subgroup analysis of ERG positive and negative cancers revealed that high CHK2 staining was significantly linked to advanced tumour stage, high Gleason score, positive nodal status, positive surgical margin, high preoperative PSA (p0.0001 each) and early prostate-specific antigen (PSA) recurrence (p=0.0001) in the subset of ERG negative cancers, while most of these associations were absent in ERG positive cancers. In ERG negative cancers, high CHK2 expression was an independent predictor of patient prognosis, even if parameters were included that were only available postoperatively. High CHK2 expression was also linked to presence of chromosomal deletions, high level of androgen receptor expression, positive p53 immunostaining, and high Ki-67 labelling index. These provide further in vivo evidence for previously described functional interactions. In summary, high CHK2 expression is linked to adverse tumour features and independently predicts early biochemical recurrence in ERG negative prostate cancer. CHK2 measurement, either alone or in combination, might be of clinical utility in this prostate cancer subgroup.

SAM pointed domain-containing Ets transcription factor (SPDEF), a member of the ETS transcription factor family, has been associated with prostate cancer development; however, its role in tumour development and progression is controversial. In the present study, SPDEF expression was analysed on a tissue microarray with >12,000 prostate cancer samples. SPDEF expression levels were higher in most prostate cancer samples than in normal prostate epithelium, suggesting SPDEF was upregulated in cancer. Nuclear SPDEF expression was identified in 80% of prostate cancer samples, and considered weak in 26.4%, moderate in 40.1% and strong in 13.5% of cases. SPDEF positivity was significantly associated with tumour stage, Gleason grade, lymph node metastasis and PSA recurrence (all P

Recent reports have described favorable response rates for immune checkpoint inhibitors in prostate cancers with microsatellite instability (MSI). However, it is unclear whether MSI affects the entire tumor mass or is distributed heterogeneously, the latter potentially impairing treatment efficiency. To identify prostate cancers with MSI, 316 advanced prostate cancers were analyzed by immunohistochemistry (IHC) for the mismatch repair (MMR) proteins MLH1, PMS2, MSH2, and MSH6 on a TMA format. Out of 200 interpretable cancers, IHC findings were consistent with MSI in 10 tumors. In 9 of these 10 cancers, tissue blocks were available for subsequent large section IHC, confirming MSI in 6 cases, each with combined protein loss of MSH2 and MSH6. One additional tumor with unequivocal loss of MLH1 and PMS2 on the TMA, for which further analyses could not be carried out due to lack of tissue, was also considered to exhibit MSI. In total, 7 of 200 interpretable advanced prostate cancers were found to exhibit MMR deficiency/MSI (3.5%). Subsequent analysis of all available cancer-containing archived tissue blocks (n=114) revealed consistent and homogeneous MMR protein loss in each case. Polymerase chain reaction (PCR)-based analysis using the “Bethesda panel” could be executed in 6 MMR deficient tumors of which 4 were MSI-high and 2 were MSI-low. The absence of intratumoral heterogeneity for the MMR status suggests that MSI occurs early in prostate cancer. It is concluded that MMR analysis on limited biopsy material by IHC is sufficient to estimate the MMR status of the entire cancer mass.

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 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.

Mesothelin is a glycoprotein which is normally expressed in only few non-vital tissues. Due to its membranous location and expression in various cancer types, it represents an attractive molecule for target-specific cancer therapies. To examine, what tumor types might benefit most from anti-mesothelin therapies, a set of tissue microarrays containing samples from 13,298 tumors from 122 different tumor types and 608 samples from 76 different normal tissue categories were analyzed for mesothelin expression by immunohistochemistry. Sixty-six (54%) of these 122 tumor types and subtypes showed at least occasional weak staining, including 49 tumor types with at least one strongly positive sample. Tumor types with highest prevalence of mesothelin positivity included ovarian cancers (serous 97%, clear cell 83%, endometroid 77%, mucinous 71%, Müllerian mixed tumors 65%), pancreatic adenocarcinoma (81%), endometrial cancers (clear cell 71%, serous 57%, Müllerian mixed tumors 50%, endometroid 45%), malignant mesothelioma (71%), and lung adenocarcinoma (55%). Mesothelin positivity was particularly rare or absent in urothelial carcinoma (10% positive out of 925), breast cancer (6% of 1,285), renal cell cancer (7% of 1,049), adenocarcinoma of the prostate (0 of 498), thyroid carcinomas (0 of 238), and soft tissue tumors (0 of 920). Significant associations with patient outcome or parameters of malignancy were not observed in 1,072 breast cancers of no special type, 925 urinary bladder cancers, 386 serous ovarian cancers, 266 lung cancers or 373 stomach cancers. Taken together, our systematic and highly standardized analysis identified numerous clinically important cancer types with frequent and high level mesothelin expression. These tumor types might benefit most from future anti-mesothelin therapies. The prognostic relevance of mesothelin appears to be low in the analyzed tumor types. Citation Format: Sören Weidemann, Natalia Gorbokon, Doris Höflmayer, Katharina Möller, David Dum, Andreas Luebke, Martina Kluth, Claudia Hube-Magg, Niclas Blessin, Guido Sauter, Jakob Izbicki, Ronald Simon, Stefan Steurer, Andreas Marx, Till Krech, Kristina Jansen, Maximilian Lennartz. Mesothelin expression in human tumor types: a tissue microarray study on more than 13,000 tumor samples [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 2833.

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.

Background: Mucin 5AC (MUC5AC) belongs to the glycoprotein family of secreted gel-forming mucins and is physiologically expressed in some epithelial cells. Studies have shown that MUC5AC is also expressed in several cancer types suggesting a potential utility for the distinction of tumor types and subtypes. Methods: To systematically determine MUC5AC expression in normal and cancerous tissues, a tissue microarray containing 10 399 samples from 111 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. Results: MUC5AC was expressed in normal mucus-producing cells of various organs. At least weak MUC5AC positivity was seen in 44 of 111 (40%) tumor entities. Of these 44 tumor entities, 28 included also tumors with strong positivity. MUC5AC immunostaining was most commonly seen in esophageal adenocarcinoma (72%), colon adenoma (62%), ductal adenocarcinoma of the pancreas (64%), mucinous carcinoma of the ovary (46%), diffuse gastric adenocarcinoma (44%), pancreatic ampullary adenocarcinoma (41%), intestinal gastric adenocarcinoma (39%), and bronchioloalveolar carcinoma (33%). Clinically relevant tumors with complete or almost complete absence of MUC5AC staining included small cell carcinoma of the lung (0% of 17), clear cell renal cell carcinoma (0% of 507), papillary thyroid carcinoma (0% of 359), breast cancer (2% of 1097), prostate cancer (2% of 228), soft tissue tumors (0.1% of 968), and hematological neoplasias (0% of 111). Conclusion: The highly standardized analysis of a broad range of cancers identified a ranking order of tumors according to their relative prevalence of MUC5AC expression.

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 >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 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.

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 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.

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.

Class III β-tubulin (TUBB3) is a component of microtubules of neuronal cells that is upregulated in various cancer entities. To better understand the role of TUBB3 in upper gastrointestinal tract cancer types, the present study assessed TUBB3 expression in tissue microarrays including 189 gastric and 428 esophageal cancer. TUBB3 expression was detected in 62.4% of gastric cancer, 73.8% of esophageal adenocarcinoma and 88.7% of esophageal squamous cell cancer, while control samples of normal esophageal and gastric epithelium were TUBB3-negative. TUBB3 positivity was not associated with the International Union Against Cancer classification, World Health Organization grading, lymph node involvement or distant metastasis in any entity. Of note, TUBB3 expression was associated with tumor localization and prognosis in gastric cancer, with the tumor stage in esophageal adenocarcinoma, and with the resection margin in esophageal squamous cell cancer. In conclusion, the substantial rate of positivity for TUBB3 already in early stages of gastric cancer in combination with the lack of a further increase in frequency with tumor stage, may suggest, that TUBB3 upregulation is rather relevant for cancer development than for cancer progression. TUBB3 might be a suitable prognostic biomarker in gastric cancer types.

Deletions of chromosome 8p occur frequently in breast cancers, but analyses of its clinical relevance have been limited to small patient cohorts and provided controversial results. A tissue microarray with 2,197 breast cancers was thus analyzed by fluorescence in-situ hybridization using an 8p21 probe in combination with a centromere 8 reference probe. 8p deletions were found in 50% of carcinomas with no special type, 67% of papillary, 28% of tubular, 37% of lobular cancers and 56% of cancers with medullary features. Deletions were always heterozygous. 8p deletion was significantly linked to advanced tumor stage (P < 0.0001), high-grade (P < 0.0001), high tumor cell proliferation (Ki67 Labeling Index; P < 0.0001), and shortened overall survival (P < 0.0001). For example, 8p deletion was seen in 32% of 290 grade 1, 43% of 438 grade 2, and 65% of 427 grade 3 cancers. In addition, 8p deletions were strongly linked to amplification of MYC (P < 0.0001), HER2 (P < 0.0001), and CCND1 (p = 0.001), but inversely associated with ER receptor expression (p = 0.0001). Remarkably, 46.5% of 8p-deleted cancers harbored amplification of at least one of the analyzed genes as compared to 27.5% amplifications in 8p-non-deleted cancers (P < 0.0001). In conclusion, 8p deletion characterizes a subset of particularly aggressive breast cancers. As 8p deletions are easy to analyze, this feature appears to be highly suited for future DNA based prognostic breast cancer panels. The strong link of 8p deletion with various gene amplifications raises the possibility of a role for regulating genomic stability.

Evidence suggests that the quantity of cytotoxic lymphocytes influences the likelihood for a successful application of immune checkpoint inhibitors. To compare the density of CD8+lymphocytes across various different tumor types, a tissue microarray (TMA) composed of up to 50 tumor samples each from 85 different cancer types and subtypes was analyzed. A total of 2652 cancers and 608 normal tissues were successfully analyzed by CD8 immunohistochemistry followed by automated image analysis of digitized slides. The median number of CD8+lymphocytes ranged from 6 cells/mm2in pleomorphic adenoma up to 1573 cells/mm2in Hodgkin’s lymphoma. CD8 counts were generally lower in normal tissues. Blood vessels of the spleen was the only non-lymphatic tissue staining for CD8.In solid tumors, highest CD8 densities (cells/mm2) were found in seminoma (median: 424), Warthin’s tumor (median: 425), squamous cell cervical cancer (median 468), medullary breast cancer (median: 657) and thymoma (median: 889).Tumor types approved for therapy with checkpoint inhibitors such malignant melanoma (median: 81), muscle invasive urothelial carcinomas (median: 119), small cell lung cancer (median: 120), clear cell kidney cancer (median: 153), squamous cell cancer (median: 189) and adenocarcinoma of the lung (median: 328) as well as Hodgkin’s lymphoma (median:1573) were all ranking among the upper half of our list. Comparably high CD8 densities (cells/mm2) were also found for several rare and aggressive cancer types including Merkel cell carcinoma (median: 70), angiosarcoma (median: 95), anaplastic thyroid cancer (median: 156), anal carcinoma (median: 104), squamous cell carcinoma of the vagina (median: 128) and embryonal carcinoma of the testis (median: 186). The CD8 cell count was highly variable within tumor types. In 73 of 84 analyzed cancer types, the CD8 count at least occasionally exceeded the average CD8 count of tumors for which checkpoint inhibitors have been approved.These data support the concept, that in most tumor types at least some individual cancers may benefit from treatment with immune checkpoint inhibitors. Citation Format: Niclas C. Blessin, Florian Lutz, Patrick Spriesterbach, Wenchao Li, Tim Mandelkow, Vera Nickelsen, Ronald Simon, Claudia Hube-Magg, Florian Viehweger, Maximillian Lennartz, Christoph Fraune, Kristine Fischer, Katharina Möller, Stefan Steurer, Jacob R. Izbicki, Guido Sauter, Sarah Minner, Frank Jacobsen, Andreas M. Luebke, Franziska Büscheck, Doris Höflmayer, Waldemar Wilczak, Eike Burandt, Andrea Hinsch. Distribution of CD8+cytotoxic lymphocytes in human neoplasms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4567.