Prognosis Of Cancer Research Articles

Plasma Cell-Free DNA Methylation-Based Prognosis in Metastatic Castrate-Resistant Prostate Cancer.

Molecular prognostication in metastatic castration prostate cancer (mCRPC) remains challenging due to the lack of validated biomarkers. This study developed a plasma cell-free DNA (cfDNA) methylation-based prognostic model in mCRPC. Targeted cfDNA methylation sequencing in 96 prostate cancer patients in different states of cancer progression revealed 78 methylation haplotype blocks (MHBs) differentially methylated from organ-confined prostate cancer to mCRPC states. Among these 78 MHBs, the top 20 MHBs were associated with mCRPC overall survival and most MHB methylation levels positively correlated with predicted circulating tumor DNA (ctDNA) fraction. By integrating the MHB-based risk score with currently available prognostic clinical variables and ctDNA fraction a prognostic nomogram was developed which showed high predictive performance for mCRPC survival (AUC = 0.99 for 6 months, AUC = 0.90 for 1 year, and AUC = 0.87 for 2 years). These findings demonstrate potential of cfDNA methylation as a molecular biology-driven biomarker for mCRPC prognosis.

Abstract 3105: Unveiling the potential of humanized bispecific antibody: a novel approach to tumor suppression in oncology

Abstract Background: AXL is a critical regulator in tumor progression, contributing to proliferation, invasiveness, epithelial-mesenchymal transition (EMT), angiogenesis, and immune modulation. High AXL levels are associated with poor prognosis in aggressive cancers. Concurrently, PD-L1 can suppress the antitumor immunity by binding to PD-1 on immune cells, a pathway already targeted by several immunotherapies. However, recent studies indicated that PD-L1's role extends beyond PD-1 binding. It seems to be involved in regulation of tumor growth, stemness, immune modulation, and DNA damage responses, many independently of PD-1. Our humanized bispecific antibody (BsAb), CPL976H, offers a unique dual-target approach by inducing internalization and lysosomal degradation of both PD-L1 and AXL, effectively diminishing their cell surface expression. Methods: The BsAb CPL976H was engineered in a VHH-Fc-VHH format, incorporating dual VHH domains against PD-L1 and AXL. The antibody’s activity, specificity, internalization, and target degradation were assessed using Western blot and flow cytometry across multiple cancer cell lines with varying target expression profiles (e.g., MDA-MB231, MCF7, A549, H1299), and after target induction with INFγ or its silencing with siRNA. RT-PCR and Western blot analyses were performed to assess impact on EMT and immune-modulating pathways. Results: CPL976H demonstrated specific, high-affinity binding to PD-L1 and AXL on diverse cancer cell lines, inducing rapid internalization and lysosomal degradation of these targets. What is important, we were able to achieved efficient targets degradation in sub-nanomolar concertation’s. This degradation led to downstream modulation of critical pathways, particularly those governing EMT and immune evasion. Notably, CPL976H impacted PD-L1 and AXL signaling disrupting cellular processes essential for tumor survival, regardless of PD-1 interaction, indicating its potential efficacy in PD-L1/PD-1 blockade-resistant cancers. Conclusions: CPL976H represents a groundbreaking advancement in oncology by targeting PD-L1 and AXL through a novel mechanism that extends beyond traditional PD-L1/PD-1 inhibition. This bispecific antibody not only mitigates immune escape but also disrupts crucial survival pathways within the tumor, offering a potent therapeutic option for patients with resistance to conventional PD-L1/PD-1 therapies. Its pronounced internalization capabilities make CPL976H a promising candidate for antibody-drug conjugate (ADC) development, which could further amplify its antitumor effects. Notably, in vivo studies confirmed the high efficacy of CPL976H, both as a standalone antibody and as an ADC, demonstrating significant tumor-suppressive effects. This in vivo validation underscores CPL976H’s potential to reshape the therapeutic landscape for challenging oncologic cases. Citation Format: Anna Jablonska, Damian Kolakowski, Tomasz Kornatowski, Aleksandra Sowinska, Sylwia Wieczorek, Krzysztof Lacek, Filip Mitula, Bartosz Wiernicki, Olga Abramczyk, Maciej Wieczorek, Delfina Popiel. Unveiling the potential of humanized bispecific antibody: a novel approach to tumor suppression in oncology [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 3105.

Abstract 2573: Single-cell multi-omics analysis identifies a novel GPRC5B-marked endothelial cell subset and its mechanistic role in tumor stemness in colorectal cancer

Abstract Introduction: Tumor endothelial cells (ECs) support the tumor microenvironment and regulate the status of tumor cells. GPRC5B, enriched in ECs, is linked to poor prognosis in colorectal cancer (CRC). Yet, the influence of GPRC5B on ECs and its regulatory mechanism on CRC stemness are still elusive. Therefore, this study aims to clarify the impact of GPRC5B on ECs states, the specific role of GPRC5B-marked ECs (GPRC5B+ ECs) in tumor/stromal interactions and the mechanisms regulating CRC stemness. Methods: We analyzed scRNA-seq data from 18 CRC samples to decode the endothelial heterogeneity. We used an original SVM-based algorithm to find EC subsets linked to CRC stemness, ultimately identifying the GPRC5B+ ECs. By deconvoluted bulk RNA-seq data, we evaluated stemness level in GPRC5B+ EC-enriched samples. Cellular interactions and spatial omics analyses were employed to examine the signaling axis between GPRC5B+ECs and CRC stem cells. ChIP-seq and hdWGCNA algorithm pinpointed upstream regulators in the axis. We also developed a GPRC5B-overexpressing EC line and co-cultured it with CRC cells, whose stemness was then assessed by spheroid formation assays and western blot. Inhibitors targeting this signaling axis were administered, and changes in stemness phenotype and key signaling molecules were measured in co-cultured CRC cells. Finally, we constructed a CT26 subcutaneous tumor mouse model and treated the mice with siRNA targeting GPRC5B (siGPRC5B) to monitor tumor growth. Tumor tissues were collected to detect the expression of stemness markers using IHC and western blot. Results: GPRC5B+ ECs exhibited high angiogenic potential, with significant ERK pathway activation. ScRNA and bulk analyses showed GPRC5B+ ECs enhance CRC stemness, which was further confirmed by the increased spheroid formation ability and enhanced expression of KLF4 and SOX2 in CRC cells after co-culturing with GPRC5B-high ECs. Mouse models showed that high GPRC5B expression in ECs fosters tumor stemness and progression. Mechanistically, multi-omics and in vitro analyses revealed that GPRC5B in ECs activated the ERK-SP1 axis to promote the expression of ADAM17, which cleaved and activated JAG1, ultimately enhancing stemness of CRC cells via JAG1/NOTCH1 interaction. Application of ERK pathway or ADAM17 inhibitors to ECs decreased tumor stemness, respectively. Besides, application of siGPRC5B effectively inhibited tumor growth in vivo. Conclusion: Through single-cell multi-omics analyses, we identified a novel GPRC5B-marked EC subset, promoting angiogenesis and CRC progression, and revealed that GPRC5B+ ECs enhance tumor stemness via the ERK/SP1/ADAM17/JAG1-NOTCH1 axis. The study offers insights into CRC endothelial heterogeneity and tumor/stromal interactions, and future targeted therapy will be conducted to elucidate its clinical application potential. Citation Format: Mengying Suo, Hongyu Huang, Tianyou Li, Ziqi Meng, Xueqian Zhang, Shanshan Jiang, Na Li. Single-cell multi-omics analysis identifies a novel GPRC5B-marked endothelial cell subset and its mechanistic role in tumor stemness in colorectal cancer [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 2573.

Abstract 2071: Spatial tracking of the pre-metastatic niche in colorectal cancer

Abstract Lymph node metastatic positively correlates with poor prognosis of colorectal cancer. Thus, it is urgent to uncover the molecular mechanisms and develop better prediction criteria of the metastasis. Tumor budding refers to the presence of a cluster of tumor cells at the leading edge of tumor invasion and metastasis. This cluster is composed of either a single tumor cell or multiple tumor cells. Tumor budding is commonly observed in various types of cancer, including colorectal cancer (CRC), on histopathological slides. It is recognized as an independent predictive factor for lymph node metastasis and prognosis. In this study, the NanoString GeoMx equipment was applied to establish the expression profile of cancer transcriptomic atlas (CTA) in CRC specimens. According to the morphology of CRC tissues determined by markers including pancytokaretin, CD45, and alpha-smooth muscle actin, the regions of interest (ROIs) were categorized into four groups, including normal, deep tumor, superficial tumor, and budding-enriched area. With digital spatial analysis, we compared the CTA expression among the four groups of regions of interests (ROIs). We characterized a marker panel for tumor budding and poorly-differentiated clusters in CRC, which tracks the progression of CRC from normal part to tumor invasive front. Our data show that the tumor budding-enriched gene panel is primarily composed of genes regulating cytoskeleton, extracellular matrix (ECM), and some secreted factors. Furthermore, our data also indicate that a morphology-based gene panel better delineates the invasion progression. Those results allow us tracking the evolution of signaling transduction for metastasis from the primary tumor to tumor budding and subsequent distant metastasis, facilitating the development of targeted drugs aimed at preventing metastasis in colorectal cancer. Citation Format: Chun Hua Hung, Chung-Ta Lee, Yu-Min Yeh, Chun-Hui Lee, Wen-Tai Liu, Meng-Ru Shen, Peng-Chan Lin. Spatial tracking of the pre-metastatic niche in colorectal cancer [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 2071.

Abstract 4601: Development and clinical translation of a phage display derived MT1-MMP-specific bicyclic peptide for radiotheranostic applications

Background: Membrane type 1 matrix metalloproteinase (MT1-MMP) is a pivotal enzyme involved in extracellular matrix remodeling, contributing to tumor invasion, metastasis, and poor prognosis in various cancers, including non-small cell lung, urothelial, pancreatic, gastric, and breast cancers. This study outlines the preclinical development and first in-human application of a phage display-derived MT1-MMP-specific bicyclic peptide, [68Ga]Ga-BCY25286, as a radiotheranostic agent for PET/CT imaging. Methods: The MT1-MMP-targeting bicyclic peptide BCY25286 was radiolabeled with either Ga-68 or Lu-177 and subsequently characterized for stability, binding affinity, and internalization. Preclinical evaluation included biodistribution and μPET/MR imaging in MT1-MMP+ HT1080 and MT1-MMP- MCF-7 xenograft tumor-bearing nude mice. For clinical translation, a 65-year-old patient with advanced pulmonary adenocarcinoma underwent [18F]FDG-PET/CT followed by [68Ga]Ga-BCY25286 PET/CT imaging, with PET scans performed after 60 minutes for [18F]FDG and up to 60 minutes for [68Ga]Ga-BCY25286 (compassionate use). Results: Radiolabeling achieved >99% radiochemical purity for both radionuclides. [68Ga]Ga-BCY25286 demonstrated highly MT1-MMP-specific binding (7.2 ± 1.6 nM), proteolytic stability up to 72 hours, and rapid background clearance, thereby enhancing imaging contrast within 30 minutes. In mice, the tracer demonstrated high tumor uptake (10.6 ± 1.1 %ID/g at 1 h p.i.) with persistence up to 24 hours. In the clinical case, [68Ga]Ga-BCY25286 PET/CT imaging revealed high uptake in both primary and biopsy-confirmed metastatic sites, corroborating the findings of [18F]FDG-PET. SUVmaxvalues were comparable for lymph node metastases but higher for bone metastases in MT1-MMP-PET compared to [18F]FDG-PET, with significant kidney retention due to renal excretion. Conclusion: This first-in-human application of MT1-MMP-targeting [68Ga]Ga-BCY25286 demonstrates the feasibility for visualization of MT-1-MMP-expressing primary tumors and metastases, which is in line with the preclinical findings. These initial clinical results support further investigation of [68Ga]Ga-BCY25286 as a diagnostic tool with potential to improve tumor characterization and patient management strategies in MT1-MMP-positive cancers. Citation Format: Ann-Christin Eder, Mohamed A. Omrane, Anusha R. Regupathy, Mohamed El Fakiri, Nils Steinacker, Lisa-Charlotte Domogalla, Christoph-Ferdinand Wielenberg, Michael Mix, Johanna Lahdenranta, Ben Blakeman, Francesca Wood, Philip Huxley, Gemma E. Mudd, Matthias Eder, Philipp T. Meyer, Martin T. Freitag. Development and clinical translation of a phage display derived MT1-MMP-specific bicyclic peptide for radiotheranostic applications [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 4601.

Abstract 2586: PAI-1 promotes tumor angiogenesis and metastasis via crosstalk between NSCLC cells and CAFs

Plasminogen activator inhibitor -1 (PAI-1) plays a multifaceted role in the tumor microenvironment, with its high expression correlated with poor prognosis in multiple cancers, including non-small cell lung cancer (NSCLC). Our group’s previous studies have shown that cancer-associated fibroblasts (CAFs) induced PAI-1 in lung cancer cells and that PAI-1 mediated the MET-targeted therapy resistance in NSCLC. In this study, we discovered that CAFs promoted PAI-1 as a secretory protein and its expression in cancer cells themselves and into the conditioned medium by the stimulation of CAF-derived stimulatory factors of transforming growth factor beta-1 (TGFb-1) and -3. Next, we used several lung cancer cell lines with different mutational profiles to assess the effect of PAI-1 in the tumor microenvironment. We investigated the phenotypic changes of lung cancer cells by recombinant human PAI-1 administration and the PAI-1 overexpressed lung cancer cell lines. PAI-1 increased the migratory ability of cancer cells and promoted epithelial to mesenchymal transition (EMT). PAI-1 contributed to tumor progression via the enrichment of EMT, extracellular matrix signaling, and inflammatory and immune responses according to gene set enrichment analysis (GSEA) revealed by the PAI-1 overexpressed lung cancer cells. Moreover, PAI-1 also promoted angiogenesis via the vascular endothelial growth factor (VEGF) pathway supported by the tube formation assay, western blot pathway analysis, and the GSEA. This impact is further validated through vivo study, in which the inhibition of PAI-1 improves the anti-cancer targeted therapy in vivo, where the tumor growth is inhibited by the combination of target therapy and the PAI-1 inhibitor, tiplaxtinin. The tumors from PAI-1 overexpressed lung cancer cells xenograft models also showed high expression of CD31 compared to control, confirming that angiogenesis is being promoted in these tumors. These findings underscore the clinical importance of PAI-1 as an important target for personalized anti-cancer drug therapy. Citation Format: Kazuhiro Okada, Ken Suzawa, Yin Min Thu, Ryunosuke Fujii, Kousei Ishimura, Ryota Fujiwara, Kazuya Hisamatsu, Ryo Yoshichika, Tomoaki Higashihara, Naohiro Hayashi, Fumiaki Mukohara, Mao Yoshikawa, Yuma Fukumoto, Keiichi Date, Hidejiro Torigoe, Kazuhiko Shien, Shinichi Toyooka. PAI-1 promotes tumor angiogenesis and metastasis via crosstalk between NSCLC cells and CAFs [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 2586.

Abstract 6568: Extracellular vesicles containing circular RNAs derived from cancer-associated fibroblasts enhance adhesion and tumor formation of gastric cancer cells in the peritoneal tissues

Abstract Purpose: The poor prognosis of gastric cancer (GC) patients is strongly associated with peritoneal recurrence. Clinically, a high level of cancer-associated fibroblast (CAF) accumulation correlates with an increased risk of peritoneal recurrence after gastric cancer resection. This observation suggested that CAFs may establish metastatic niches in peritoneal tissues, distant from the primary GC. Extracellular vesicles (EVs) have been identified as key transporter for stable communication between donor and recipient cells, even over long distances. Taken together, CAF-derived EV may play a crucial role in creating a metastatic precondition at the mesothelial cells lining the peritoneal tissue. Understanding the mechanisms underlying this process may provide new insight into therapeutic strategies for preventing peritoneal recurrence in GC patients. Methods: We collected formalin-fixed paraffin-embedded (FFPE) primary GC tissues from the patients who developed peritoneal recurrence (PR group, n=5), and patients without recurrence during follow-up (Non-PR group, n=5). CAF accumulation was assessed using Mason’s trichrome staining, and circular RNA (circRNA) arrays were performed on those tissues. The expression of candidate circRNAs in cell lysates and EVs from various GC cell lines and non-cancerous cells including CAFs using qRT-PCR. The effect of CAF-derived EVs on the adhesion between mesothelial cells and cancer cells was evaluated via adhesion assay. Furthermore, CAF culture media and cancer cells were injected into the mouse peritoneum to assess the number of tumor nodules formed. Results: We observed that CAFs are more significantly accumulate in GC tissues of the PR group compared to the Non-PR group. Six circRNAs were identified as being more abundant in the PR group based on the circRNA array. Among those, that circTSSC2, circALG1, and circALG1L2 were more abundant in CAF cell lysate and CAF-derived EVs compared to GC cells, mesothelial cells, and other immune cells. The resistance to treatments with actinomycin D and RNAse R and the Sanger’s sequencing confirmed the circular structure of those RNAs. CAF-derived EVs were shown to enhance adhesion between mesothelial cells and cancer cells in our experimental models. Additionally, CAF-conditioned media significantly increased the number of tumor nodules formed in the mouse peritoneum. Conclusions: This study suggests that the EVs including specific circRNAs, secreted by CAFs accumulated in primary GC tissues, may contribute to the formation of a pre-metastatic niche in peritoneal tissues of GC patients. Those CAFs-derived EVs could serve as predictive markers for peritoneal recurrence after GC resection and as therapeutic targets to mitigate the risk of peritoneal metastatic recurrence. Citation Format: Yulim Lee, Hoon Hur, In-Hye Ham. Extracellular vesicles containing circular RNAs derived from cancer-associated fibroblasts enhance adhesion and tumor formation of gastric cancer cells in the peritoneal tissues [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 6568.

The Role of Visfatin in Gastric and Esophageal Cancer: From Biomarker to Therapeutic Target

Background: Gastric and esophageal cancers are among the most lethal malignancies worldwide, necessitating improved biomarkers and therapeutic targets to improve patient outcomes. Visfatin, also known as nicotinamide phosphoribosyltransferase (NAMPT), is a metabolic enzyme and adipokine with emerging significance in cancer progression. It has been implicated in tumor cell proliferation, angiogenesis, immune modulation, and chemotherapy resistance, yet its clinical relevance in upper gastrointestinal (GI) cancers remains unclear. This review aims to explore visfatin’s biochemical properties, its role in the pathogenesis of upper GI cancers, and its implications for potential therapeutic interventions. Methods: A comprehensive review of the literature was conducted to evaluate the role of visfatin in gastric and esophageal cancer. We analyzed studies investigating visfatin expression in tumor tissues, blood, and adipose tissue, its prognostic significance, and its potential as a therapeutic target. Preclinical and clinical studies evaluating visfatin inhibitors were also reviewed. Results: Visfatin promotes tumor progression through the activation of key oncogenic pathways leading to increased angiogenesis, epithelial–mesenchymal transition (EMT), and immune suppression. Elevated visfatin levels are associated with advanced tumor stage, reduced response to chemotherapy, and poor prognosis in both gastric and esophageal cancers. Therapeutic agents targeting visfatin, such as the inhibitor FK866, have shown promising results in reducing tumor proliferation by >50%, improving chemoresistance, and restoring antitumor immunity in preclinical studies. However, clinical translation remains limited due to toxicity concerns and the need for more targeted therapies. Conclusions: Visfatin is a promising biomarker and potential therapeutic target in gastric and esophageal cancer. However, its precise role and mechanisms require further investigation. The standardization of measurement techniques and large-scale clinical studies is needed to validate its prognostic and predictive value. Future research should focus on optimizing visfatin-targeted therapies, particularly in the context of obesity-associated malignancies and chemoresistant tumors.

Abstract 1987: Circulating tumor cell-based molecular responses stratify EGFR-TKI efficacy in EGFR-mutant lung cancer patients

Abstract Background: Liquid biopsy offers a minimally invasive alternative to tissue biopsy, enabling therapeutic monitoring, precision medicine-based treatment decisions, and detection of tumor heterogeneity. Circulating tumor cell (CTC) analysis is a promising minimally invasive biomarker for monitoring treatment response and stratifying prognosis in EGFR-mutant non-small cell lung cancer (NSCLC). Meanwhile, detection of CTCs in peripheral blood is challenging due to their rarity and the limitations of both marker-dependent and marker-independent isolation techniques, which may compromise sensitivity and specificity. Continuous Centrifugal Microfluidics - Circulating Tumor Cell Disc (CCM-CTCD) enriches heterogeneous CTCs through automated microfluidic extraction and leukocyte depletion without interrupting centrifugation. Method: In this study, 77 EGFR-mutant NSCLC patients treated with EGFR-TKIs were enrolled. CTCs were isolated using CCM-CTCD before and after EGFR-TKI treatment and compared with plasma cfDNA and tissue biopsy for EGFR mutation analysis. CK-positive, CD45-negative CTCs were isolated and visualized using immunofluorescence staining. Patients were categorized as CTC molecular responders or non-responders based on a ≥30% reduction in CTC count from baseline. Progression-free survival (PFS) and tumor burden changes were evaluated. Results: The CCM-CTCD method showed concordance with Cobas® liquid biopsy but demonstrated superior sensitivity in detecting EGFR mutations. Mutational discordance between tissue, plasma cfDNA, and CTCs highlighted tumor heterogeneity. CTC molecular responders had significantly longer median PFS (46.3 vs. 12.2 months) and greater tumor burden reduction (-39.2% vs. -32.2%, p = 0.025) compared to non-responders. Multivariable analysis revealed that CTC molecular response was an independent predictor of improved PFS (HR 0.45, p = 0.023). Additionally, a non-significant trend was observed toward shorter PFS in patients receiving later-line treatments compared to first-line (HR 1.30, p = 0.523), first- or second-generation EGFR-TKIs compared to third-generation EGFR-TKIs (HR 1.59, p = 0.196), and in those with a history of smoking (HR 1.45, p = 0.300). CTC profiling was found to complement traditional methods for identifying genomic alterations and predicting early progression. Conclusion: CTC analysis using CCM-CTCD demonstrates potential as a reliable tool for predicting treatment response and stratifying prognosis in EGFR-mutant NSCLC. Stratifying patients based on CTC molecular response may guide treatment intensification strategies, offering a pathway for risk-adapted precision oncology. Prospective studies are warranted to validate these findings and optimize therapeutic decision-making. Citation Format: Seoyoung Lee, Chaeyeon Kim, Chang Gon Kim, Min Hee Hong, Mina Han, Wonrak Son,Gamin Kim, Minseok Kim, Hye Ryun Kim. Circulating tumor cell-based molecular responses stratify EGFR-TKI efficacy in EGFR-mutant lung cancer 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 1987.

Abstract 6250: Clinical significance of co localization index in rectal cancer: a deep learning approach to cell interaction analysis

Abstract Background: Tumor tissue is not just a cluster of cancer cells, but an organized ecosystem in which various cells, extracellular matrices, and various types of liquid factors interact with each other. There are high technical barriers to processing this complex ecosystem in large quantities and quantitatively. Therefore, we have established a histological analysis method using deep-learning-based imaging cytometry (DL-IC) (Abe T, Yamashita K, et al. Anticancer Res. 43:3755 2023). Identification of the constituent cells of tumor tissue and spatial understanding of the tumor immune microenvironment using DL-IC are important for predicting cancer prognosis and treatment efficacy. In this study, we propose a co-localization index (CLI) as a new indicator for analyzing the tumor immune microenvironment using AI. Purpose: We investigated the impact of the co-localization of cytotoxic lymphocytes and cancer cells on the prognosis of rectal cancer after surgery. Subjectsand Methods: Forty rectal cancer surgical specimens were analyzed using the DL-IC system Cu-Cyto. A bit pattern kernel filtering algorithm was implemented to prevent duplicate cell counting, and its performance on immunohistochemistry (IHC) specimens was evaluated. The accuracy was compared between analyses with and without the algorithm. Cell-cell interactions were quantified using CLI, and the usefulness of CLI as a prognostic indicator was evaluated, particularly focusing on interactions between cancer cells and CD8+ T cells. Additionally, a comprehensive analysis of CLI was conducted using combinations of multiple cell types. Results: In the training process, where the data size of the training data was scaled, the F1 scores for adenocarcinoma cells, lymphocytes, and CD8+ T cells were 0.589, 0.889, and 0.911, respectively, at a cell number of 1013. The introduction of a bit pattern kernel filtering algorithm improved the accuracy of the determination of each cell type. The 5-year disease-free survival rate was significantly prolonged in the high CLI group between cancer cells and CD8+ T cells (P=0.041), and multivariate analysis also showed that it was an independent prognostic factor. On the other hand, there was no significant difference in the 5-year overall survival rate (P=0.41). Furthermore, it was found that the CLI of the three-way interaction between cancer cells, macrophages, and CD8+ T cells was also an independent prognostic factor. Conclusion: Cu-Cyto has achieved highly accurate cell determination by introducing a bit pattern kernel filtering algorithm. CLI has shown correlation with patient prognosis as an objective and reproducible quantitative evaluation method for cell-cell interactions. In the future, it will be necessary to elucidate the oncological and biological significance of the combinations of each cell type. Citation Format: Kimihiro Yamashita, Tomoki Abe, Toru Nagasaka, Masayuki Ando, Takao Tsuneki, Yukari Adachi, Takaaki Tachibana, Hiroki Kagiyama, Tomoaki Aoki, Yasufumi Koterazawa, Ryuichiro Sawada, Hitoshi Harada, Yasunori Otowa, Naoki Urakawa, Hironobu Goto, Hiroshi Hasegawa, Shingo Kanaji, Takeru Matsuda, Ryohei Sasaki, Yoshihiro Kakeji. Clinical significance of co localization index in rectal cancer: a deep learning approach to cell interaction analysis [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 6250.

Abstract 3084: Claudin-11 promotes cisplatin resistance by inducing autophagy through activation of the PHF23-ERK signaling pathway in ovarian cancer cells

Abstract Claudin-11, a member of claudins consisting of tight junction has been shown to be associated with prognosis and to play dual roles in cancer. However, its role in the response to anti-cancer agents is unknown. In this study, we investigated the role and mechanism of claudin-11 in cisplatin resistance in ovarian cancer. Kaplan-Meier survival analysis using The Cancer Genome Atlas data revealed that high CLDN11 expression is significantly associated with poor prognosis in ovarian cancer. Claudin-11 expression was significantly upregulated in cisplatin-resistant ovarian cancer cells. Consistent with this, claudin-11 overexpression significantly decreased the sensitivity to cisplatin in ovarian cancer cells. Cisplatin-induced apoptosis was reduced in claudin-11-overexpressing ovarian cancer cells, which was associated with decreased DNA damage. Moreover, claudin-11 overexpression inhibited cisplatin-induced apoptosis by promoting autophagy through increased ERK phosphorylation in ovarian cancer cells. The cisplatin sensitivity of claudin-11-overexpressing cells was restored by co-treatment with chloroquine, an autophagy inhibitor, and cisplatin, indicating that claudin-11 promotes cisplatin resistance by inducing autophagy. RNA sequencing data analysis further showed that autophagy-related PHD finger protein 23 (PHF23) is significantly upregulated in claudin-11-overexpressing cells compared with vector-transfected cells. PHF23 knockdown reversed cisplatin resistance by inhibiting ERK phosphorylation and then cisplatin-induced autophagy and apoptosis in claudin-11-overexpression cell. Taken together, these results indicate that claudin-11 promotes cisplatin resistance by activating autophagy through the PHF23-ERK signaling pathway and thereby reducing apoptosis in ovarian cancer cell, suggesting that inhibition of claudin-11 may overcome cisplatin resistance in ovarian cancer. Citation Format: Ha Yeong Chae, So Young Lee, Hyojin Jeong, Hye Ri You, Jinil Han, Young Kee Shin, Mi Jeong Kwon. Claudin-11 promotes cisplatin resistance by inducing autophagy through activation of the PHF23-ERK signaling pathway in ovarian cancer cells [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 3084.

Abstract 2939: The effect of cSNX1.3 on MMTV-PyMT tumor growth and metastasis

Abstract The Epidermal Growth Factor Receptor (EGFR) belongs to a group of Receptor Tyrosine Kinases (RTKs) that are a part of the HER family. EGFR mediates many processes in the cell including proliferation, migration, and survival however its overexpression is correlated with poor prognosis in several epithelial cancers including Triple Negative Breast Cancer (TNBC). In healthy cells, EGF binds to EGFR dimerizes and undergoes transphosphorylation, and can then be intracellularly imported where it is taken to the early endosome and awaits ubiquitination. This signals readiness to be taken to the lysosome where it undergoes degradation or in some cases, gets recycled. In cancerous cells, however, ubiquitination gets inhibited due to their loss of polarity. This results in failure to signify readiness to be taken to the lysosome which allows EGFR to completely evade degradation and undergo nuclear localization. This process is initiated by the binding of Sorting Nexin 1 (SNX1), a protein responsible for the regulation of trafficking, to EGFR. Considering the interaction between Sorting Nexins and RTKs causes oncogenic activity, it was hypothesized in this lab that a therapeutic that can modify this interaction can alter tumor-specific retrotranslocation. In order to target these interactions, the therapeutic peptide, cSNX1.3, was developed. cSNX1.3 is a cell-penetrating peptide with a Protein Transduction Domain that allows for the delivery of peptides across the cell membrane and into the intracellular domain. cSNX1.3 interacts with EGFR when it’s in the long-lived endosome and binds in competition with SNX1. When cSNX1.3 is bound to EGFR, it is able to inhibit the nuclear localization of the RTK and as a result, inhibit its oncogenic activity. In order to fully evaluate the tumor-regressing abilities of cSNX1.3, we used an immunocompetent model of transgenic Whey Acidic Protein - Transforming Growth Factor alpha (WAP-TGFα) mice, whose mammary gland tumors are EGFR dependent. These mice were treated with cSNX1.3 or the control drug, cPTD4, over the course of 4 weeks. After completion of treatment, it was determined that the tumors of the cPTD4-treated mice continued to grow whereas the tumors of the cSNX1.3-treated mice began to regress. We then decided to construct an additional study using another immunocompetent mouse model that would also demonstrate how cancer metastasis reacted to cSNX1.3 treatment, given that metastasis is typically what makes breast cancer fatal in humans. For these reasons, we decided to use a model of transgenic Mouse Mammary Tumor Virus - Polyoma Middle T (MMTV-PyMT) mice. Conducting an evaluation of cSNX1.3 using this model that closely resembles the function of metastatic breast cancer in humans, will allow us to better understand the future of cSNX1.3 as a breast cancer therapeutic for human applications. Citation Format: Delina J. Denogean, Barbara Sands, Joyce Schroeder. The effect of cSNX1.3 on MMTV-PyMT tumor growth and metastasis [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 2939.

Abstract 2171: Amezalpat, a peroxisome proliferator-activated receptor alpha (PPARα) antagonist, inhibits suppressive macrophage development, activation and function

Amezalpat (TPST-1120) is a first-in-class, small molecule competitive antagonist of peroxisome proliferator-activated receptor alpha (PPARα), the master transcriptional regulator of fatty acid oxidation (FAO). Analysis of biomarker data from a previous Phase I study demonstrated amezalpat dose-dependent changes in immune genes associated with myeloid populations. Suppressive M2 macrophages are a prominent myeloid population associated with poor prognosis in many cancers. As M2 macrophages are reliant on FAO, we sought to assess the effects of amezalpat on development, activation and function of these cells. Flow cytometry analysis of M2 macrophages polarized in the presence of amezalpat displayed concentration-dependent reductions in canonical M2 macrophage markers CD163, CD206, and Arg-1 (p<0.05 by Wilcoxon’s test). ELISA measurement of cytokine production by amezalpat-treated M2 macrophages demonstrated a statistically significant reduction in the suppressive cytokines IL-10 (n=8; p<0.05 by Wilcoxon’s test) and TGF-β (n=3 by One-way ANOVA), suggesting amezalpat-induced functional impairment of this population. Additionally, amezalpat treatment of M2 macrophages caused significant reductions in mitochondrial mass, measured with a mitochondria-specific dye by flow cytometry (p<0.01 by two-sample T test). Finally, in co-cultures of M2 macrophages with autologous activated CD8+ T cells and HCC tumor cells (SNU-449), amezalpat induced tumor cell cytotoxicity and M2 cell death commensurate with cell-type specific expression levels of its target PPARα. Together, these data suggest amezalpat modulates suppressive macrophage development and function and supports the contribution of an immune-mediated mechanism to anti-tumor activity reported in clinical studies. Citation Format: Mandy I. Cheng, Ademola Esomojumi, Dara Burdette, Valerie Chen, Jorg H. Fritz, Sam Whiting, Nathan Standifer. Amezalpat, a peroxisome proliferator-activated receptor alpha (PPARα) antagonist, inhibits suppressive macrophage development, activation and function [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 2171.

Abstract 6678: Targeting long non-coding RNA LINC00324 using novel plant-derived exosome-like nanovesicles loaded with anticancer epigenetic modifiers effectively inhibits biomarkers of epithelial-mesenchymal transition in breast cancer

Abstract Despite recent advancements in the diagnostics and therapeutics of breast cancer, it continues to be the second leading cause of death among women worldwide. Therefore, identifying new potential biomarkers and molecular targets is essential for enhancing the diagnosis and treatment of BC patients. A wealth of evidence underscores the significant role of long non-coding RNAs in various biological processes, including tumorigenesis, which might offer new biomarkers and molecular targets for improved cancer detection and treatment. In this context, long intergenic non-coding RNA 00324 (LINC00324) has been associated with advanced cancer stage, larger tumor size, lymph node metastasis, and poorer prognosis across several cancer types. However, its biological function and molecular mechanisms in breast cancer remain largely unexplored. This study adopts an innovative approach aimed at challenging existing knowledge and research methodologies, with the goal of making significant advancements in breast cancer research. By exploring the role of LINC00324 as an oncogene in tumorigenesis and progression, the study may uncover crucial downstream oncogenic signaling pathways related to Epithelial-Mesenchymal Transition (EMT), which are linked to the hallmark features of breast cancer pathogenesis. This research could ultimately lead to the identification of a new biomarker for the diagnosis and prognosis of breast cancer, thereby transforming our understanding and treatment of the disease. In this study, we employed an innovative approach to downregulate the expression of LINC00324 across various breast cancer cell lines, ranging from well-differentiated to poorly differentiated types. This was accomplished using isolated novel plant-derived exosome-like nanovesicles (PELNVs), demonstrating specific biological effects, including anti-inflammatory and anti-tumor properties, while exhibiting minimal toxic side effects. PELNVs were a novel vehicle for delivering anticancer epigenetic modifier drugs and specific siRNA targeting LINC00324. Additionally, we investigated several downstream target biomarkers of epithelial-mesenchymal transition, including oncogenic targets such as Notch1, Notch4, Nanog, s6 kinase, β-catenin, and Stat3, both in vitro and in vivo. These findings suggest that LINC00324 could serve as a novel biomarker for diagnosis and prognosis. Outcome: Identifying the molecular classification of breast cancer subtypes based on the expression of individual biomarkers, such as LINC00324, might lead to the development of novel therapeutic biomarkers/targets for early detection, drug resistance, and personalized cancer treatments. Using PELNVs for drug delivery may inspire future research on plant-derived nanovesicles. Citation Format: Alaa Ashraf Al_Aaser, Nourhan El-Sayed El-Feel, Ahmed Samir Sultan. Targeting long non-coding RNA LINC00324 using novel plant-derived exosome-like nanovesicles loaded with anticancer epigenetic modifiers effectively inhibits biomarkers of epithelial-mesenchymal transition in breast cancer [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 6678.

Abstract 652: Exploring the therapeutic benefit of AVA-NP-695 with combination modalities in ICB refractory and rare cancers

Abstract Background: Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) expression is associated with poor prognosis in many cancers. Previous studies identified ENPP1 as the primary hydrolase of extracellular cGAMP, that activates the anticancer STING pathway. High ENPP1 expression is found in several tumors, including human astrocyte tumors and triple-negative breast cancer (TNBC) cell lines, where it contributes to tumor progression and impedes T cell infiltration. By inhibiting cGAS-STING-mediated immune activation and producing adenosine, an immune suppressor that promotes cell migration, ENPP1 plays a critical role in tumor growth. Interestingly, surface and global proteome analyses identify ENPP1 as potential immunotherapeutic targets in case of rare cancers like sarcomas. Methods: The inhibition potency of AVA-NP-695 was confirmed by 5’TMP and 2’2’-cGAMP enzymatic assays. Pharmacokinetic profile of AVA-NP-695 in Mice, Rats and Beagle Dogs and the human PK profile was predicted. The efficacy of AVA-NP-695 was demonstrated in 4T1 Tumor bearing BALB/c mice as monotherapy and in combination with anti-PD-L1, Olaparib and Paclitaxel. Finally, in vivo the effect of pharmacological inhibition of DDR with Olaparib in combination with AVA-NP-695 was assessed in OS models. Results: We demonstrate that AVA-NP-695, a selective and potent small molecule ENPP1 inhibitor, exhibited no adverse effects in multiple safety studies in mice and beagle dogs. In vivo studies revealed that AVA-NP-695 (6 mg/kg BID) provided superior tumor growth inhibition and reduced metastasis compared to Olaparib and Anti-PD1 in a syngeneic 4T1 breast cancer mouse model. Additionally, AVA-NP-695 demonstrates tumor regression in both paratibial (OT) and metastatic (lung) models of Osteosarcoma (OS). AVA-NP-695 significant increase the cGAMP levels (∼2-3 fold) as early as 6h post-treatment, without additional stimulation. A targeted pharmacological screen revealed synthetic lethality when combining AVA-NP-695 with Olaparib (PARPi) in vitro OS cell lines. This novel combination increased both intra- and extracellular cGAMP production. Additionally, the pharmacological inhibition of DDR with Olaparib in combination with AVA-NP-695 led to OS tumor regression and enhanced antitumor immune responses in both OT and metastatic contexts. Compassionate use of AVA-NP-695 showed > 80% tumor volume reduction in Canine patients. Conclusions: The potent anti-tumor efficacy of AVA-NP-695 both as monotherapy and combination along with its safety profile provides a strong rationale for the therapeutic potential of AVA-NP-695 against solids tumors (breast cancer and Osteosarcoma). Our results uncover novel mechanistic vulnerabilities and suggest that treatment with AVA-NP-695 in combination may increase effectiveness in patients, thus preventing local and distant dissemination. Citation Format: Borja Ruiz-Fernandez de Cordoba, Avijit Goswami, Sandeep Goyal, Kawaljit Singh, Princy Khurana, Alejandro Sweet-Cordero, Aditya Kulkarni. Exploring the therapeutic benefit of AVA-NP-695 with combination modalities in ICB refractory and rare cancers [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 652.

Abstract 3346: CD44 is an independent predictor of lymph node metastasis in differentiated thyroid cancer

Abstract Background: Differentiated Thyroid Carcinoma (DTC), a common endocrine malignancy, has witnessed a significant rise in global incidence over the past few decades. Despite its indolent nature and favorable prognosis, the clinical course of DTC varies extensively, with lymph node metastasis being an important risk factor in prognosis. CD44 has been shown to be associated with prognosis in various cancers. However, its role in DTC is not well explored. Methods: A total of 1703 DTC cases of Middle Eastern ethnicity were included in the study. CD44 expression was evaluated by immunohistochemistry using tissue microarray to analyze the clinico-pathological associations. Univariate and multivariate logistic regression analysis was used to determine the predictors of lymph node metastasis. Results: CD44 over-expression was noted in 69.7% (1187/1703) of DTC cases and was significantly associated with younger age (< 55 years; p < 0.0001), multifocality (p < 0.0001), lymphovascular invasion (p = 0.0007) and lymph node metastasis (p < 0.0001). Interestingly, on multivariate logistic regression analysis, CD44 was found to be an independent predictor of lymph node metastasis (Hazard ratio = 1.79; 95% confidence interval = 1.40 - 2.30; p < 0.0001). Conclusion: Our study showed that CD44 expression was an independent predictive biomarker of lymph node metastasis in Middle Eastern patients with DTC. Detection of CD44 expression could help identify patients at risk for developing lymph node metastasis and help in individualization of clinical management for DTC patients. Citation Format: Syed Zeeshan Qadri, Abdul K. Siraj, Sandeep K. Parvathareddy, Nabil Siraj, Padmanaban Annaiyappanaidu, Khawla S. Al-Kuraya. CD44 is an independent predictor of lymph node metastasis in differentiated thyroid cancer [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 3346.

Mechanism of etoposide resistance in small cell lung cancer and the potential therapeutic options.

Small cell lung cancer (SCLC) is a type of high-grade neuroendocrine malignancy with low gene mutation. Chemotherapy is the major treatment strategy, but long-term clinical application often leads to drug resistance. Etoposide is a first-line drug approved by the US Food and Drug Administration for SCLC treatment, but etoposide-resistance is a problem. In this study, a SCLC cell line with etoposide-acquired resistance, H1048-ER, was constructed through a concentration gradient increasing method, and its resistance to etoposide was investigated in vitro and in a zebrafish model. Through transcriptome sequencing, real-time reverse transcription-quantitative polymerase chain reaction, and bioinformatic analyses of H1048-ER vs. H1048 cells, 51 differentially expressed genes were found to be significantly enriched in "collagen degradation" and "MET/FAK signaling activation in ECM". Among them, six genes (COL11A1, COL26A1, COL4A3, COL4A4, LAMA4, and LAMC1) had strong correlations with the prognosis of lung cancer. They may be key factors in the acquired etoposide resistance of H1048-ER cells. H1048-ER cells showed cross-resistance to cisplatin but were sensitive to doxorubicin and temozolomide. Our study provides novel insights into etoposide resistance in SCLC and affords the potential treatment options after etoposide resistance.

Preoperative assessment and prognostic prediction of gastric cancer patients with peritoneal metastasis using 18F-FDG PET/CT before conversion surgery

BackgroundConversion therapy followed by conversion surgery (CS) can improve the prognosis of gastric cancer (GC) patients with peritoneal metastasis (PM). However, patients benefit differently. There is no way to confirm the prognostic benefit non-invasively and early. This retrospective study assessed the value of 18F-FDG PET/CT after conversion therapy in preoperative assessment and prognostic prediction of GC patients with PM.ResultsFifty-one GC patients with PM were enrolled. 18F-FDG PET/CT after conversion therapy helped in preoperative assessment. Its diagnostic accuracy for residual peritoneal lesions was slightly better than contrast-enhanced CT (72.5% vs. 61.2%, P = 0.229), although the difference was not statistically significant. TBR of peritoneal lesions could help preoperative assessment, with TBR of peritoneal lesions to the mediastinal blood pool SUVmax (TBRAmaxp) as the best predictor (cutoff = 0.705, specificity 80%, sensitivity 80%, AUC 0.825, P < 0.001). Additionally, PET/CT could predict prognosis and assess surgical benefit. SUVmax of peritoneal lesions (SUVmaxp) was the best predictor of 24 months survival (cutoff = 1.466, AUC 0.870, P = 0.002, Specificity 77.8%, Sensitivity 83.3%) and metabolic parameters of peritoneal lesions could predict OS and the prognosis of patients who underwent CS.Conclusion18F-FDG PET/CT provides quantitative imaging indicators for preoperative evaluation and prognostic prediction in GC patients with PM.

Abstract 2112: Association between visceral fat obesity and perioperative complications of undernutrition in laparoscopic surgery for colorectal cancer

Abstract Background: Visceral obesity and malnutrition are each associated with poor prognosis in gastrointestinal cancers. This study investigates the impact of undernutrition combined with visceral obesity on perioperative complications in laparoscopic colorectal cancer surgery. Methods: We retrospectively analyzed 223 colorectal cancer patients who underwent curative laparoscopic resection at our institution between January 2010 and December 2011. Undernutrition was defined as the Geriatric Nutritional Risk Index (GNRI), calculated using the ideal body weight ratio and serum albumin level, with GNRI &amp;lt; 107 indicating undernutrition. Visceral obesity was defined as a visceral fat area (VFA) &amp;gt;100 cm2 at the umbilical level. Patients were divided into two groups: those with both undernutrition and visceral obesity (n=40) and others (n=183). Associations with perioperative complications were analyzed, along with background factors including age, gender, BMI, albumin (Alb), CRP, tumor markers, and other nutritional indices. Additionally, a new nutritional status score for predicting postoperative complications was developed using ROC curve analysis based on easily measurable indicators from blood tests, CT scans, and physical exams. Results: The malnutrition and visceral obesity group showed a significantly higher incidence of Grade 2 or higher perioperative complications compared to the other group (25.0% vs. 10.9%; p = 0.037). Analysis of nutritional and oncological indicators identified age, BMI, VFA, CRP, lymphocyte count, and CA19-9 as associated with postoperative complications. A novel nutritional status score incorporating these factors predicted Grade 2 or higher complications with a sensitivity of 43.0% and a specificity of 83.3%. Conclusions: Undernutrition combined with visceral obesity significantly increased the risk of perioperative complications. Preoperative nutritional interventions to improve patient status may reduce these risks and should be further investigated. Citation Format: Kengo Haruna, Norikatsu Miyoshi, Shiki Fujino, Rie Mizumoto, Rie Hayashi, Mitsunobu Takeda, Yuki Sekido, Tsuyoshi Hata, Atsushi Hamabe, Takayuki Ogino, Mamoru Uemura, Hirofumi Yamamoto, Yuichiro Doki, Hidetoshi Eguchi. Association between visceral fat obesity and perioperative complications of undernutrition in laparoscopic surgery for colorectal cancer [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 2112.

Abstract 5147: Prognostic role of MTAP expression is reversed by the ERG status in prostate cancer treated by radical prostatectomy

Abstract Loss of S-methyl-5′-thioadenosine phosphorylase (MTAP) expression offers an important therapeutic option through synthetic lethality with inhibitors targeting related pathways, and has been linked to resistance to immune checkpoint inhibitors in several tumor types. To better understand the prevalence and clinical relevance of MTAP expression in prostate cancer, a tissue microarray with 17, 747 prostate cancer samples and a molecular and clinical database was analyzed for MTAP expression by immunohistochemistry. Normal prostate glands showed a weak to moderate, predominantly cytoplasmic MTAP positivity of epithelial and stromal cells. In 13, 189 interpretable cancers, a complete loss of MTAP staining as compared to adjacent non-neoplastic cells was seen in 33 (0.3%) tumors, while MTAP staining was considered 1+ in 14.8%, 2+ in 42.2%, and 3+ in 42.7% of tumors. Fluorescence in situ hybridization analysis of 9 MTAP negative cancers confirmed homozygous MTAP deletion in all of these tumors. MTAP staining was significantly stronger in cancers harboring the TMPRSS2:ERG fusion than in TMPRSS2:ERG fusion negative tumors (p&amp;lt;0.0001). A comparison with clinico-pathological features revealed inverse correlations depending on the ERG fusion status: In ERG negative carcinomas, high (3+) MTAP expression was linked to advanced pT stage, high classical and quantitative Gleason grade, and early PSA recurrence in uni- and multivariate analysis (p&amp;lt;0.0001 each). In ERG positive cancers, MTAP expression decreased with advanced pT stage (p&amp;lt;0.0001), classical (p=0.0004) and quantitative Gleason grade (p=0.0005), and low (1+) MTAP expression was significantly linked to early PSA recurrence (p=0.0012). Comparison with 11 previously analyzed chromosomal deletions identified ERG-status-dependent positive or negative associations between MTAP expression and deletions of PTEN and 12p13 (p≤0.0274) suggesting possible functional interactions with PTEN and one or several 12p genes. Taken together, the results of our study demonstrate that MTAP deficiency is exceedingly rare in prostate cancer, while high MTAP expression is a strong and independent marker for poor prognosis in ERG negative cancers. Citation Format: Natalia Gorbokon, Seyma Büyücek, Henning Plage, Neele Heckmann, Ronald Simon, Maximilian Lennartz, Martina Kluth, Elena Bady, Lisa Hornsteiner, Claudia Hube-Magg, Sarah Minner, Eike Burandt, Till S Clauditz, Waldemar Wilczak, Guido Sauter, David Dum, Andrea Hinsch, Hans Heinzer, Alexander Haese, Thorsten Schlomm, Andreas Lübke, Markus Graefen, Stefan Steurer, Christian Bernreuther, Luca Roma, Lukas Bubendorf, Sarah Weinberger. Prognostic role of MTAP expression is reversed by the ERG status in prostate cancer treated by radical prostatectomy [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 5147.