Abstract Phosphoserine aminotransferase 1 (PSAT1) is an enzyme involved in de novo biosynthesis of L-serine by catalyzing the conversion of 3-phosphohydroxy-pyruvate to 3-phosphoserine. This reaction simultaneously produces α-ketoglutarate, thereby directly linking serine biosynthesis to glutamine metabolism, the tricarboxylic acid cycle and one carbon metabolism. L-serine is a vital substrate for numerous cellular processes such as the synthesis of proteins and neurotransmitters as well as nucleotide production and cell proliferation. Previous studies have linked PSAT1 upregulation to enhanced tumor cell proliferation, invasion and migration in various tumor entities, thereby suggesting a crucial role for PSAT1 in cancer development and progression. To learn more on the prevalence of PSAT1 expression and potential associations with phenotype across human malignancies, this study analyzed PSAT1 protein expression in a cohort of 14,966 tumor tissue samples from 134 different tumor entities in a tissue microarray format. PSAT1 staining was cytoplasmic and/or nuclear and occurred in various normal cell types and was seen in at least a fraction of cases in most tumor entities (124 of 134; 91.8%). Out of the 12,305 interpretable tumor samples, PSAT1 staining was found in 4,633 samples, including 3,168 (25.7%) with weak, 765 (6.2%) with moderate, and 700 (5.7%) with strong positivity. PSAT1 staining positivity was particularly frequent and high level in granular cell tumor (92.7%), urothelial carcinoma of the bladder (47.7-91.0%), embryonal carcinoma of the testis (88.4%), several subtypes of uterine cancer (65.1-87.5%), adrenal cortical adenoma and carcinoma (65.2-86.0%), ovarian cancer (15.4-84.6%), colorectal neuroendocrine carcinoma (63.3%), paraganglioma (63.3%), and in squamous cell carcinomas from different sites (50.6-62.2%). High PSAT1 expression was associated with unfavorable tumor phenotype in invasive breast carcinoma of no special type, clear cell renal cell carcinoma, papillary renal cell carcinoma, gastric adenocarcinoma, adenocarcinoma of the colon, and endometrioid endometrial carcinoma (p≤0.05 each). Low PSAT1 expression was associated with invasive tumor growth in urothelial carcinoma (p≤0.05 each). In conclusion, our data establish PSAT1 as a highly upregulated metabolic enzyme across a broad spectrum of human tumors. Its potential as both a prognostic biomarker and a therapeutic target is supported by an association with aggressive clinicopathological features in numerous tumor types. Citation Format: Fiete Gehrisch, Hendrina Contreras, Maximilian Lennartz, Katharina Möller, Nathalia Gorbokon, Martina Kluth, Claudia Hube-Magg, Maria Christina Tsourlakis, Nina Schraps, Florian Viehweger, David Dum, Andrea Hinsch, Christoph Fraune, Christian Bernreuther, Patrick Lebok, Guido Sauter, Till S. Clauditz, Till Krech, Andreas H. Marx, Ronald Simon, Eike Burandt, Sarah Minner, Stefan Steurer, Ria Schlichter, Seyma Büyücek. Prevalence and significance of PSAT1 expression in human cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 543.

Glucose transporter 1 (GLUT1) is a key protein for transmembranous glucose uptake of cells which is often overexpressed in cancer. To better comprehend the prevalence and role of GLUT1 expression in different cancer types, a tissue microarray containing 14,966 samples from 134 different tumor entities was analyzed in this study. GLUT1 expression was generally markedly higher in cancer than in corresponding normal tissues. A total of 122 of 134 tumor categories showed GLUT1 expression in at least 1 case, and 97 tumor categories included at least 1 case with strong GLUT1 staining. The frequency of GLUT1 positivity was particularly high in squamous cell carcinomas of various sites of origin (92.9

Abstract The two mutually exchangeable ATPases SMARCA2 and SMARCA4 form the two catalytic subunits of a polymorphic family of SWI/SNF complexes. In both normal and malignant cells, they play a regulatory role in numerous essential cellular processes. For example, SWI/SNF affects the regulation of cell differentiation, programmed cell death, DNA repair, chromosome stability, signaling pathway crosstalk and cell metabolism. Topical interest in SMARCA4/SMARCA2 is due to the observation of their synthetic lethal relationship, potentially offering new therapeutic approaches. Targeting SMARCA4 deficient cancer cells with SMARCA2 inhibitors or degraders has resulted in significant growth inhibition in experimental systems and further agents are being tested in early clinical trials. To determine the prevalence of SMARCA2/SMARCA4 expression in cancer, a tissue microarray containing 14,966 samples from 134 different tumor entities and 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. SMARCA2 immunostaining was absent in 6.9%, weak in 8.0%, moderate in 18.3%, and strong in 66.8% of 12,253 interpretable tumors. SMARCA4 staining was absent in 0.7%, weak in 1.9%, moderate in 5.9%, and strong in 91.5% of 13,093 interpretable tumors. Remarkably, losses of SMARCA2 and SMARCA4 were strongly correlated. Of 91 SMARCA4 deficient tumors for which SMARCA2 data were also available, 28 (30.8%) did also show a complete loss of SMARCA2 expression. SMARCA2 deficiency was most commonly seen in Burkitt lymphoma (66.7%), endometrial carcinomas (up to 57.1%), rhabdoid tumors (50.0%) and ovarian carcinomas (up to 37.8%). SMARCA4 staining was predominantly lost in in neuroendocrine carcinomas (up to 25.0%), endometrioid carcinomas (up to 7.7%) and adenocarcinomas of the lung (7.5%). Absent or low SMARCA2 expression was significantly linked to unfavorable tumor phenotype in clear cell renal cell carcinoma, bladder cancer, and breast cancer while weak or absent SMARCA4 staining was linked to unfavorable tumor features in colorectal and clear cell renal cell carcinoma (p≤0.05). It is concluded, that SMARCA4 deficiency is a rather rare event in tumors, whereas SMARCA2 deficiency is much more common in many different tumor entities and is associated with unfavourable cancer characteristics in several tumor types. The frequent co-deficiency of SMARCA2 and SMARCA4 challenges the concept of a synthetic lethal relationship of these proteins in vivo. Citation Format: Nina Schraps, Anne Menz, Florian Lutz, Viktoria Chirico, Florian Viehweger, David Dum, Ria Schlichter, Andrea Hinsch, Fiete Gehrisch, Christoph Fraune, Christian Bernreuther, Seyma Büyücek, Martina Kluth, Claudia Hube-Magg, Katharina Möller, Viktor Reiswich, Andreas M. Luebke, Patrick Lebok, Baris Mercanoglu, Nathaniel Melling, Thilo Hackert, Guido Sauter, Maximilian Lennartz, Till S. Cauditz, Andreas H Marx, Ronald Simon, Stefan Steurer, Eike Burandt, Natalia Gorbokon, Maria Christina Tsourlakis, Sarah Minner, Till Krech, Morton Freytag. SMARCA2 and SMARCA4 expression in cancer: A tissue microarray study on 14,966 tumors from 134 different tumor types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2980.

ABSTRACT Background Carbohydrate antigen 19–9 (CA19‐9) is a cell surface glycoprotein widely used as a diagnostic and prognostic serum marker for monitoring pancreatic cancer. The aim of this study was to evaluate the prevalence and clinical relevance of CA19‐9 expression in human cancer. Methods To comprehensively determine the prevalence and clinical relevance of CA19‐9 expression in cancer, a tissue microarray containing 14,966 samples from 134 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. Results The staining results were categorized into four groups according to the percentage of CA19‐9‐positive tumor cells and the staining intensity. At least an occasional CA19‐9 positivity was found in 79 of 134 tumor categories with 66 containing at least one strongly positive case. CA19‐9 positivity was most frequent in biliopancreatic adenocarcinomas (84.4%–95.4%), adenocarcinomas of the upper and lower gastrointestinal tract (54.7%–74.4%), embryonal carcinomas of the testis (93.5%), and endometrioid endometrial carcinomas (87.5%). High CA19‐9 staining was associated with advanced pT‐stage, pN1, L1 (p < 0.0001 each), V1 (p = 0.0239), mismatch repair protein deficiency (p = 0.0067), and BRAF V600E mutation (p = 0.0005) in colorectal adenocarcinoma. Reduced CA19‐9 staining was associated with distant metastasis (p = 0.0067) in clear cell renal cell carcinoma, advanced pT‐stage (p = 0.0277) in papillary renal cell carcinoma, high grade (p = 0.0129) in breast cancer and with invasive tumor growth (pTa vs. pT2‐4, p < 0.0001) and high grade (p = 0.0367) in urothelial carcinoma. Conclusions It is concluded that a high CA19‐9 expression, as found in pancreatic adenocarcinoma, occurs in subsets of various other cancer types. Patients with such tumors could potentially benefit from CA19‐9 serum monitoring, for example in terms of response to treatment, recurrence or predicting prognosis. Cancer type dependent associations between high or low CA19‐9 expression and aggressive tumor phenotype are in line with the complex and variable functional role described for CA19‐9 in cancer.

Background/Objectives: Thymidylate synthase (TYMS) represents an important therapeutic target. Methods: In this study, TYMS expression was analyzed by immunohistochemistry on a tissue microarray containing 17,371 samples from 136 different tumor types. Results: TYMS staining was seen in 42.9% of 15,361 analyzable tumors, with weak staining in 35.4%, moderate in 5.7%, and strong in 1.8%. TYMS occurred in at least one case of 127 categories, of which 71 showed TYMS staining in at least 50% of cases, and 56 included at least one case with strong positivity. TYMS positivity occurred most commonly in lymphomas (81.3–96.5%), sarcomas and sarcomatoid carcinomas (33.3–100%), malignant melanoma (70.5–90.7%), cervical adenocarcinoma (78.3%), and squamous cell carcinomas of various sites (57.1–77.9%). High TYMS expression was linked to advanced pT (p = 0.0097), high grade (p < 0.0001), ER negativity (p < 0.0001), and PR negativity (p = 0.0002) in invasive breast cancer of no special type; high grade (p < 0.0050), high UICC stage (p = 0.0060), and nodal metastasis (p = 0.0120) in clear cell renal cell carcinoma (RCC); high grade (p < 0.05) and nodal metastasis (p = 0.0045) in papillary RCC; high Gleason grade (p < 0.0001) and advanced pT stage (p = 0.0149) in prostatic adenocarcinoma; high pT (p < 0.0001), nodal metastasis (p = 0.005), lymphatic (p = 0.0064) and venous invasion (p = 0.0005), left side location (p < 0.0001), and microsatellite instability (p < 0.0001) in colorectal adenocarcinoma; and high grade (p < 0.0001) in squamous cell carcinomas of different sites. Conclusions: TYMS is often overexpressed across different cancer entities and shows associations with several adverse histopathological parameters commonly used to describe tumor phenotypes.

Abstract Prostate-specific membrane antigen (PSMA) is a transmembraneous glycoprotein that serves as a diagnostic and therapeutic target in prostate cancer. Beyond prostate malignancies, PSMA expression can also be detected in tumor cells and in endothelial cells (ECs) of newly formed, tumor-associated blood vessels across various other malignancies. To evaluate the prevalence of PSMA expression in both tumor cells and tumor-associated neovasculature, 12,409 tumors from 135 different tumor types, were analyzed by immunohistochemistry in a tissue microarray format. PSMA positivity in tumor cells was detected in 46 tumor entities, including 13 with at least one strongly positive case. Tumor cell PSMA positivity was frequently observed in prostatic adenocarcinoma (84.2-98.7%), granular cell tumor (76.5%), basal cell adenoma of the salivary gland (64.3%), as well as in endometrial (up to 60.7%) and ovarian carcinomas (up to 13.8%). In prostate cancer, PSMA expression was higher in Gleason 4+4 and 5+5 cancers (96.4-98.7%) compared to Gleason 3+3 cancers (94.7%), while it was lowest in recurrent cancers after hormonal therapy (84.2%; p<0.0001). In breast cancer of no special type, PSMA positivity was linked to high grade (p=0.0451), ER- (p=0.0279), and PR-negativity (p=0.0135). PSMA positivity in ECs of tumor-associated vasculature occurred in 4,888 of 10,658 (45.9%) tumors. 123 tumor entities had at least one case with PSMA positive ECs, 106 included at least one sample with many PSMA-positive vessels and 102 had at least one case with strong vessel positivity. EC PSMA positivity was most frequent in renal cell carcinoma (RCC) (88.7-88.9%), adenocarcinoma of the uterine cervix (82.4%) endometrioid endometrial carcinoma (76.7%), colorectal adenocarcinoma (70.5%), cholangiocarcinoma (66.7%), chondrosarcoma (63.5%), HCC (62.5%), and squamous cell carcinomas from different sites (up to 88.2%). The number of positive vessels tightly correlated with their staining intensity (<0.0001) and both parameters were often associated with features of cancer aggressiveness. PSMA staining quantity and intensity in vessels were associated with tumor stage (p=0.0343), tumor grade (p<0.0001), ER- (p=0.0002) and PR-negativity (p=0.0351) in invasive breast carcinoma, multiple grading and staging systems (p=0.0022-0.0388) in clear cell RCC, Fuhrman grade (p=0.0091) and metastatic disease (p=0.0175) in papillary RCC, pT stage (p<0.0001) in urothelial carcinoma, pT stage (p=0.0459), nodal positivity (p=0.0089) and lymphatic invasion (p=0.0023), mismatch repair (MMR) deficiency (p=0.0178) and BRAF mutations (p=0.0026) in colorectal adenocarcinoma, and MMR deficiency (p=0.0089) in gastric adenocarcinoma. It is concluded that PSMA expression in tumor cells is largely limited to few cancer entities while EC positivity is common in a broad range of cancer types. Citation Format: Fiete Gehrisch, Alexandra Malinowski, Anne Menz, Florian Lutz, Viktoria Chirico, Florian Viehweger, David Dum, Ria Schlichter, Andrea Hinsch, Christoph Fraune, Christian Bernreuther, Seyma Büyücek, Martina Kluth, Claudia Hube-Magg, Georgia Makrypidi-Fraune, Nina Schraps, Katharina Möller, Andreas M. Luebke, Patrick Lebok, Guido Sauter, Maximilian Lennartz, Frank Jacobsen, Till S. Clauditz, Andreas H. Marx, Ronald Simon, Stefan Steurer, Eike Burandt, Nathalia Gorbokon, Maria C. Tsourlakis, Sarah Minner, Till Krech, Morton Freytag, Viktor Reiswich. PSMA expression in neoplastic cells and tumor-associated vasculature: A tissue microarray study evaluating 12,409 cancers from 135 different tumor types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2990.

Abstract Background Homozygous 9p21 deletions are the major cause for MTAP deficiency, making cancer cells more vulnerable towards drugs targeting various pathways. This study aimed to assess the prevalence of heterozygous and homozygous 9p21 deletions in cancer. Methods A tissue microarray containing 7,172 samples from 125 different tumor entities was analyzed by fluorescence in situ hybridization. This method allows the detection of deletions within single tumor cells, while admixted non-neoplastic cells are omitted. Consecutive sections were immunostained for MTAP and p16 ( CDKN2A ). Results Among 4,999 evaluable tumors, 10.7% had heterozygous and 7.4% homozygous deletions, which occurred in different tumor categories. Homozygous deletions were most frequent in mesothelioma (up to 47.8%), pancreatic ductal adenocarcinoma (44.7%), and urothelial carcinoma (up to 36.4%) while heterozygous deletions predominated in squamous cell carcinoma (up to 34.3%), leiomyosarcoma (31.4%), and esophageal adenocarcinoma (30.8%). The proportion of homozygous 9p21 deletions was high in mesothelioma (up to 91.6%), urothelial carcinoma (up to 80.0%), and pancreatic ductal adenocarcinoma (76.4%), intermediate in squamous cell carcinomas of different organs (12.5–50.0%) and pulmonary adenocarcinoma (46.3%), and low in endometrioid (9.1%) and high-grade serous (4.0%) ovarian carcinoma. MTAP and p16 immunostaining was absent in homozygous 9p21 deletions, while heterozygously deleted cancers showed markedly decreased MTAP immunostaining ( p < 0.0001), with unchanged p16 staining. Conclusions These data provide a comprehensive overview on the prevalence on homozygous and heterozygous 9p21 deletions in cancer and demonstrate that different cancer types markedly differ in their ratio of homozygous/heterozygous 9p21 deletions. The strong concordance between homozygous 9p21 deletions and absent MTAP immunostaining highlights the effectiveness of immunohistochemistry in detecting MTAP deficiency.

BackgroundGlutathione peroxidase 2 (GPX2) has a pivotal role in removing reactive oxygen species (ROS) from cells. Although the number of studies analyzing GPX2 in cancer is still limited, data suggesting a role of altered GPX2 expression in various cancer types are accumulatin.MethodsTo better comprehend the role of GPX2 expression in cancer, GPX2 was analyzed by immunohistochemistry on tissue microarrays containing 18,555 samples from 148 different tumor types.ResultsA total of 95 of 148 tumor categories showed GPX2 expression in at least one case, and 61 tumor categories contained at least one strongly positive case. GPX2 positivity was most seen in colorectal adenocarcinomas (97.9%) and adenomas (100%), non-invasive urothelial carcinomas (88.9-100%), pancreatico-biliary cancers (83.4-94.7%), Brenner tumors of the ovary (89.7%), gastro-esophageal adenocarcinomas (83.1-87.3%), and seminomas (85.6%). Clinically important cancer types with infrequent and often weak GPX2 staining included sarcomas, lymphomas, high-grade serous ovarian carcinomas, prostatic adenocarcinomas, melanomas, mesotheliomas, and renal cell carcinomas. Reduced GPX2 staining was linked to microsatellite instability (MSI, p<0.0001), advanced pT stage (p=0.0044), nodal metastasis (p=0.0093), V1 (p=0.0020) and L1 (p=0.0057) in colorectal adenocarcinoma, invasive growth (p<0.0001), high grade (p=0.0013), nodal metastasis (p=0.0005), V1 (p=0.0004) and L1 (p=0.0001) in urothelial carcinoma, high grade in pancreatic ductal adenocarcinoma (p=0.0233), and MSI in gastric adenocarcinoma (p=0.0325).ConclusionIt is concluded, that GPX2 expression is common in cancer and preferably occurs in tumor entities derived from normal cell types with high GPX2 expression. In these tumors, reduced GPX2 expression is often linked to features of aggressive disease.

Background. Annexin A3 (ANXA3) is a member of the annexin family of calcium-dependent phospholipid-binding proteins and plays a major role in various membrane-related processes. Marterial & Methods. ANXA3 expression was analyzed by immunohistochemistry (IHC) on tissue microarrays (TMAs) containing 17,285 samples from 148 different tumor types. Results. ANXA3 staining was seen in 10,223 (75.9%) of the 13,472 interpretable tumors and was considered weak in 16.3%, moderate in 10.1%, and strong in 49.4% of cases. Of 148 tumor categories, 128 showed ANXA3 expression in at least one case, and 110 included at least one case with strong staining. High ANXA3 expression was linked to high grade (p<0.0001), muscle invasive growth (pTa vs pT2-4; p<0.0001) and high pT-stage (p=0.0267) in urothelial carcinoma; lymphatic invasion (p=0.0307) in colorectal adenocarcinoma; high pT-stage (p=0.0211) in gastric adenocarcinoma; high pT-stage (p<0.0001), nodal positivity (p=0.0004) and high grade (p<0.0001) in hepatocellular carcinoma; and high pT-stage (p=0.0410) in papillary thyroid carcinoma. Low ANXA3 expression was linked with lymphatic invasion (p<0.0001) in urothelial carcinoma, high tumor grade in invasive breast carcinoma of no special type (p<0.0001); high UICC- (p=0.0008) and pT-stage (p<0.0001) in clear cell renal cell carcinoma; high ISUP grade (p=0.0135), high UICC- (p=0.0073) and pT-stage (p=0.0003) in papillary renal cell carcinoma; advanced pT-stage (p=0.0464) in pancreatic ductal adenocarcinoma; high pT-stage (p=0.0056) and mismatch repair deficiency (p<0.0001) in colorectal adenocarcinoma; and high pT-stage (p=0.0427) in endometrioid endometrial carcinoma. Conclusion. It is concluded, that ANXA3 is abundantly expressed across a broad spectrum of cancer entities and that it exerts a tissue-dependent oncogenic or tumor-suppressive role.

Abstract Annexin A4 (ANXA4) is a member of the annexin family of calcium-dependent phospholipid-binding proteins. In line with its capability to bind to phospholipid membranes, it has roles in processes related to membrane dynamics such as membrane trafficking, vesicle aggregation, membrane organization, and ion channel regulation. ANXA4 dysregulation can contribute to abnormal cell migration, proliferation, and resistance to apoptosis. ANXA4 overexpression has been described in several cancer types and has been linked to tumor aggressiveness and treatment resistance. Due to its differential expression in tumors versus normal tissues, ANXA4 is being investigated as a diagnostic biomarker. To learn more on the role of ANXA4 in cancer, ANXA4 expression was analyzed by immunohistochemistry (IHC) on tissue microarrays (TMAs) containing 6,058 samples from 105 different tumor types. ANXA4 staining was seen in 3,649 (75.4%) of the 4,839 analyzable tumors, and was considered weak in 11.3%, moderate in 17.5%, and strong in 46.6% of cases. Of 105 tumor categories, 100 (95.2%) showed ANXA4 expression in at least one case, 92 (87.6%) showed ANXA4 staining in more than 50% of cases, and 90 (85.7%) included at least one case with strong ANXA4 positivity. Highest rates of strong ANXA4 positivity occurred in adenocarcinoma of the ampulla Vateri (100%) and ductal adenocarcinoma of the pancreas (96.0%), gallbladder adenocarcinoma (100%), gastric adenocarcinoma (93.0-99.1%), clear cell (97.7%), papillary (97.4%) and chromophobe (94.9%) renal cell carcinoma (RCC), Brenner tumor (96.4%), colorectal adenocarcinoma (95.0%), clear cell carcinoma of the ovary (94.7%), adenocarcinoma of the esophagus (94.7%), oncocytoma od the kidney (94.6%), hepatocellular carcinoma (91.8%), mucinous carcinoma of the ovary (90.9%), cholangiocarcinoma of the liver (88.6%), adenocarcinoma of the cervix uteri (87.0%), endometrioid endometrial carcinoma (76.1%), endometrioid carcinoma of the ovary (66.7%), and in urothelial carcinoma of the kidney pelvis (66.7%). The 1,219 evaluable breast cancers of no specific type (NST) represented the largest subset of tumors from one entity. In these tumors, ANXA4 staining was negative in 642 (52.7%), weak in 84 (6.9%), moderate in 169 (13.9%), and strong in 324 (26.6%) cases. A comparison with tumor phenotype revealed that low ANXA4 expression was linked to advanced pT-stage (p<0.0001), high grade of malignancy (p=0.0018), and nodal metastasis (p=0.0247). In summary, our data provide a comprehensive overview on ANXA4 expression in cancer. They demonstrate, that ANXA4 is often expressed at high levels in a broad range of different tumor entities. At least in breast cancer NST, a low level of ANXA4 expression is a feature of high cancer aggressiveness. Citation Format: Cosima Völkel, Nayma Malas, Fiete Gehrisch, Nina Schraps, Anne Menz, Florian Lutz, Viktoria Chirico, Florian Viehweger, David Dum, Ria Schlichter, Andrea Hinsch, Christoph Fraune, Christian Bernreuther, Seyma Büyücek, Martina Kluth, Claudia Hube-Magg, Georgia Makrypidi-Fraune, Katharina Möller, Andreas M. Luebke, Patrick Lebok, Guido Sauter, Maximilian Lennartz, Till S. Clauditz, Andreas H. Marx, Ronald Simon, Eike Burandt, Natalia Gorbokon, Maria C. Tsourlakis, Sarah Minner, Till Krech, Morton Freytag, Viktor Reiswich, Stefan Steurer. Expression of annexin A4 in cancer: A tissue microarray study involving 6,058 cancers from 105 tumor entities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1115.

Abstract Annexin A3 (ANXA3) is a member of the annexin family of calcium-dependent phospholipid-binding proteins which plays a major role in various membrane-related processes, including membrane organization, repair, vesicle trafficking, and regulation of ion channels. Its diverse functions extend across various cellular processes such as apoptosis, cell growth, inflammation, and differentiation. Altered ANXA3 expression has been found in several cancer types. To better comprehend the role of ANXA3 in cancer, ANXA3 expression was analyzed by immunohistochemistry (IHC) on tissue microarrays (TMAs) containing 5,914 samples from 105 different tumor types. ANXA3 staining was seen in 3,490 (72.3%) of the 4,824 analyzable tumors, and was considered weak in 18.2%, moderate in 10.2%, and strong in 44.0% of cases. Of 105 tumor categories, 87 (82.9%) showed ANXA3 expression in at least one case, 69 (65.7%) showed ANXA3 staining in at least 50% of cases, and 78 (74.3%) included at least one case with strong ANXA3 positivity. Among tumors with at least 10 evaluable samples, the highest rates of tumors with strong ANXA3 positivity were observed in ampullary (100.0%) and ductal adenocarcinoma of the pancreas (90.9%), adenocarcinoma of the cervix uteri (95.7%),gastrointestinal stromal tumor (GIST; 90.4%), colorectal adenocarcinoma (90.0%), gastric adenocarcinoma of the intestinal (88.7%) and diffuse (81.6%), basal cell carcinoma of the skin (88.2%), gallbladder adenocarcinoma (88.2%),esophageal adenocarcinoma (87.8%), prostatic adenocarcinoma (83.8%), endometroid (82.5%), serous (78.9%) and mucinous (72.7%) carcinoma of the ovary, papillary renal cell carcinoma (63.2%), cholangiocarcinoma (77.8%), endometroid (76.3%) and serous (50.0%) endometrial carcinoma, squamous cell carcinomas from different organs of origin (up to 61.9%), testicular seminoma (53.8%), carcinosarcoma of the ovary (53.3%), lobular (52.3%), mucinous (40.0%) and tubular (38.9%) carcinoma of the breast, clear cell carcinoma of the ovary (42.1%), muscle-invasive urothelial carcinoma (41.4%), carcinosarcoma of the uterus (40.0%), Brenner tumor (39.3%), invasive breast carcinoma of no special type (NST; 36.1%), urothelial carcinoma of the kidney pelvis (29.8%) and yolk sac tumors of the testis (27.3%). In breast cancer NST, low ANXA3 expression was linked to aggressive tumor phenotype. Strong ANXA3 staining was seen in 100.0% of Gleason 3+3, 87.3% of Gleason 4+4, and in 65.8% of Gleason 5+5 carcinomas of the prostate (p<0.0001). In breast cancer NST, low ANXA3 expression was linked to high grade of malignancy (p<0.0001). In summary, the data from this study provide a catalogue of ANXA3 expression in human cancer, demonstrate that ANXA3 levels are highly variable in most tumor entities, and show that ANXA3 immunostaining is associated with prognostic tumor features in at least some tumor types. Citation Format: Clara von Bargen, Nayira Hakimi, Fiete Gehrisch, Anne Menz, Florian Lutz, Viktoria Chirico, Florian Viehweger, David Dum, Ria Schlichter, Andrea Hinsch, Christoph Fraune, Christian Bernreuther, Seyma Büyücek, Martina Kluth, Claudia Hube-Magg, Georgia Makrypidi-Fraune, Nina Schraps, Katharina Möller, Andreas M. Luebke, Patrick Lebok, Guido Sauter, Maximilian Lennartz, Till S. Clauditz, Andreas H. Marx, Ronald Simon, Eike Burandt, Natalia Gorbokon, Maria C. Tsourlakis, Sarah Minner, Till Krech, Morton Freytag, Viktor Reiswich, Stefan Steurer. Annexin A3 expression is prevalent but highly variable in human cancer: A tissue microarray study involving 5,914 cancers from 105 tumor entities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5371.

TIM-3 (T-cell immunoglobulin and mucin-domain containing-3) is an inhibitory immune checkpoint molecule which mainly occurs in subsets of inflammatory cells. On the surface membrane of cancer cells TIM-3 may represent a druggable target. To assess the prevalence of TIM-3 expression in cancer, a tissue microarray containing 17, 172 samples from 134 different tumor types and subtypes was analyzed by immunohistochemistry (IHC). TIM-3 expression of tumor cells and macrophages were semiquantitatively recorded. In cancer cells, a membranous TIM-3 positivity was predominantly seen in clear cell (61.9%) and papillary (62.5%) renal cell carcinomas (RCCs) but - less commonly - also in Hodgkin’s (25.0%) and non-Hodgkin’s lymphomas (up to 9.1%), epithelial thymomas (6.9%), ovarian carcinomas (0.7%-1.4%), seminomas (0.4%), and several mesenchymal neoplasms (up to 16.0%). High TIM-3 expression of tumor cells was linked to low grade (p=0.0079), low UICC stage (p=0.0085), low pT (p<0.0001), and pN0 (p=0.0067) in clear cell RCC (ccRCC), and to pM0 (p=0.0177) in papillary RCC (pRCC). TIM-3 expression of macrophages occurred in all tumor entities but its relationship with parameters of aggressive disease varied between entities. A high quantity of TIM-3 positive macrophages was linked to unfavorable tumor parameters such as high grade (p<0.0001), advanced pT stage (p=0.0126), and distant metastasis (p=0.0069) in ccRCC, as well as high grade (p<0.0001), HER2 positivity (p=0.0015), and absence of estrogen (p<0.0001) and progesterone receptor (p=0.0187) expression in invasive breast carcinomas of no special type. A high number of TIM-3 positive macrophages was linked to favorable tumor parameters such as L0 (p=0.0333) and V0 (p=0.0161) in mismatch repair protein proficient colorectal carcinoma, low pT (p=0.0128), L0 (p=0.0333), and V0 (p=0.0161), as well as a lack of rete testis (p=0.0053) and spermatic cord infiltration (p=0.0365) in testicular seminoma. It is concluded that tumor cell TIM-3 expression among epithelial or mesenchymal tumors is largely restricted to RCCs where high expression is associated with parameters of non-aggressive disease. TIM-3 expression in tumor associated macrophages is abundant and its clinical significance varies between tumor entities. Maximilian Lennartz, David Dum, Christian Bernreuther, Patrick Lebok, Guido Sauter, Andreas H Marx, Ronald Simon, Christoph Fraune, Natalia Gorbokon, Eike Burandt, Sarah Minner, Stefan Steurer, Till S Clauditz, Till Krech. TIM-3 expression in human cancer: A tissue microarray study on 17, 172 patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3207.

Background/Objectives: Aberrant expression of high-mobility group protein B1 (HMGB1) has been linked to cancer development and progression. Methods: To better comprehend the role of HMGB1 expression in cancer, a tissue microarray containing 14,966 samples from 134 different tumor entities and 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. Results: Strong HMGB1 staining occurred in almost all normal cell types and in most cancers. Of 11,808 evaluable cancers, only 7.8% showed complete absence of HMGB1 staining (HMGB1 deficiency) while 9.9% showed 1+, 25.0% showed 2+, and 57.2% showed 3+ HMGB1 positivity. Absence of HMGB1 staining mostly occurred in pheochromocytoma (90.0%), seminoma (72.4%), gastrointestinal stromal tumor (28.6%), adrenal cortical carcinoma (25.0%), and Hodgkin’s lymphoma (25.0%). Low HMGB1 staining was linked to poor histologic grade (p < 0.0001), advanced pT stage (p < 0.0001), high UICC stage (p < 0.0001), and distant metastasis (p = 0.0413) in clear cell renal cell carcinoma, invasive tumor growth in urothelial carcinoma (pTa vs. pT2–4, p < 0.0001), mismatch repair deficiency (p = 0.0167) in colorectal cancers, and advanced pT stage in invasive breast carcinoma of no special type (p = 0.0038). Strong HMGB1 staining was linked to nodal metastases in high-grade serous ovarian carcinomas (p = 0.0213) and colorectal adenocarcinomas (p = 0.0137), as well as to poor histological grade in squamous cell carcinomas (p = 0.0010). Conclusions: HMGB1 deficiency and reduced HMGB1 expression occur in a broad range of different tumor entities. Low rather than strong HMGB1 staining is often linked to an aggressive tumor phenotype. Whether HMGB1 deficiency renders cells susceptible to specific drugs remains to be determined.