Citations

Abstract Introduction: Breast cancer genome-wide association studies (GWAS) have identified over 200 susceptibility loci, many replicated in diverse populations. However, cross-ancestry evaluation of breast cancer genetic architecture remains limited. We examined breast cancer genetic architecture using GWAS summary results from European (EUR; cases (ca) = 188,474, controls (co) = 96,201), East Asian (EAS; ca = 20,393, co = 86,329), African American (AA; ca = 9,235, co = 10,184), and US Hispanic/Latina and Latin American (H/L; ca = 2,396, co =7,468) studies. Methods: GWAS results were derived from the Breast Cancer Association Consortium, the African Ancestry Breast Cancer Genetics Consortium (AABCG), Biobank Japan, and a meta-analysis of five studies of H/L women with breast cancer. Linkage disequilibrium (LD) scores were generated for EUR, EAS, and AMR using the 1000 Genomes Project, while AA LD scores were derived from a subset of AABCG controls. Heritability was estimated for each ancestry group using LD score regression. Genetic correlations between populations were assessed via Popcorn. Polygenicity was analyzed using GENESIS; however, due to the limited sample size in the H/L studies, these estimates were restricted to AA, EAS, and EUR. Enrichment of heritability across regulatory elements was evaluated using stratified LD score regression across all populations. Results: The logit-scale heritability and corresponding standard error (SE) were 0.466 (0.066) for EAS, 0.501 (0.050) for EUR, 0.588 (0.360) for H/L, and 0.614 (0.095) for AA. The estimated number of independent susceptibility loci was 4,446 for EAS, 5,235 for EUR, and 8,308 for AA. Using a clumping and thresholding approach, an optimal set of common variants were projected to explain 38.6% (EUR), 39.4% (EAS), and 26.2% (AA) of genetic variance for samples of 100,000 cases and 100,000 controls with AUCs from corresponding estimated polygenic risk scores (PRSs) of 0.621 (EUR), 0.634 (EAS), and 0.611 (AA). Genetic correlations were strongest between EUR and EAS (ρ = 0.79, SE = 0.08) and EUR and H/L (ρ = 0.68, SE = 0.21), and weakest between AA and EAS (ρ = 0.42, SE = 0.14) and AA and H/L (ρ = 0.26, SE = 0.24). Among 73 genomic features, we found significant (P < 0.05/73) enrichment in heritability in EUR for ‘ancient promoter’ regions, transcription factor binding sites, H3K4me3, ‘super-enhancers’, H3K4me1, H3K27ac; in EAS for ‘super-enhancers’; and in AA for H3K27ac. No genomic features were significantly enriched in H/L, likely due to limited power. Conclusion: These findings suggest a shared breast cancer genetic architecture across diverse populations, as well as the potential for a similar level of breast cancer risk stratification by PRS in these populations. Expanding GWAS in underrepresented populations is essential to improve genetic risk predictions and foster equitable cancer prevention. Citation Format: James L. Li, Maria Zanti, Jacob Williams, Om Jahagirdar, Guochong Jia, Qiang Hu, Jean-Tristan Brandenburg, Li Yan, Weang-Kee Ho, Jingmei Li, José P. Miranda, Devika Godbole, Julie-Alexia Dias, Leila Dorling, Wenlong C. Chen, Nicholas Boddicker, Ying Wang, Alicia Martin, Martin J. Zhang, Yan Zhang, Joe Dennis, Esther M. John, Gabriela Torres-Mejia, Larry Kushi, Jeffrey Weitzel, Susan L. Neuhausen, Luis Carvajal-Carmona, Christopher Haiman, Elad Ziv, Laura Fejerman, Wei Zheng, Dezheng Huo, Douglas Easton, Nilanjan Chatterjee, Peter Kraft, Montserrat Garcia-Closas, Wendy Wong, Kyriaki Michailidou, Qianqian Zhu, Diptavo Dutta, Thomas U. Ahearn, Haoyu Zhang. Genetic architecture of breast cancer across diverse populations: Assessing heritability, genetic correlation, and polygenicity [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 2282.

Abstract Approximately two-thirds of hypopharyngeal squamous cell carcinoma (HPSCC) are diagnosed in advanced stage, with the worst prognosis among head and neck squamous cell carcinomas (HNSCCs). Identifying biomarkers for high-risk patients who need aggressive treatment is crucial. We present mutational, transcriptomic and proteomic studies of 103 Chinese HPSCC patients, observing a higher prevalence and poorer prognosis in males comparing to females. Genes in estrogen response pathways are up-regulated and proteins phosphorylated by protein kinase C (PKC) and Cyclin-dependent kinases (CDKs) are aberrantly regulated. We identify aberrant copy number regions including SOX2 (3q26.33), FGFR (8p11.23), CCND1 (11q13.3), CDKN2A/2B (9p21.3), and MYC (8q24.21). HPV status combined with highly mutated genes as predictive markers was assessed, including SYNE1 in HPV(-), MUC4 in HPV(+) patients. We confirm the presence of four known gene expression (GE) subtypes of HNSCC in our HPSCC cohort and present the genomic alterations, patient characteristics and survival status of each subtype. A predictive model involving clinical factors and transcriptomic expression of six genes was established and cross-site validated. The findings open new opportunities for stratifying high-risk patients and molecular targets for novel therapeutic strategies. Citation Format: Yanxin Ren, Wei Xiong, Chun Feng, Dan Yu, Xiaoyan Wang, Qing Yang, Siting Yu, Hongjiang Zhang, Bangyun Huo, Honglu Jiang, Zuli Li, Junlin Wang, Yu-Xiong Su, Ping Yang, Yong Liao, Qi Zhong, Junwen Wang. Multi-omics insights into the molecular signature and prognosis of hypopharyngeal squamous cell carcinoma [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 4999.

Abstract Introduction: Src Family Kinases (SFKs) have a crucial role in tumor proliferation, survival, and metastasis. NXP900 is a highly selective SFK inhibitor a novel mechanism of action that locks SFKs in a closed, inhibited conformation, preventing interaction with substrate proteins, unlike other SFK inhibitors like dasatinib. A phase 1 study of NXP900 in patients with advanced solid tumors was recently initiated. Our preclinical studies showed therapeutic efficacy of NXP900 in cholangiocarcinoma (CCA) through decreased YAP, RAF-MAP and PI3K-AKT signaling. Here, we examined mechanisms of sensitivity and resistance to SFK inhibition. Methods: Secondary resistance was explored by generating a NXP900-resistant human cell line (HuCCT1-R) via prolonged exposure to NXP900, followed by multiomic profiling. Primary resistance was studied in vivo using nine heterogeneous patient-derived xenograft (PDX) tumors implanted in the flanks of NOD/SCID mice. Tumor-bearing mice were treated with vehicle or 40 mg/kg NXP900 daily for up to 4 weeks. To identify factors associated with response, a multiomic approach was used, integrating RNA-Seq, global proteomics, and phosphoproteomics. A hierarchical-all-against-all algorithm (HallA) assessed associations between multiomic features and drug response in tumor growth. Kinase enrichment analysis (KEA3) identified features linked to sensitivity or resistance. Results: HuCCT1-R cells showed increased pTyr abundancy of TNK2, a protein known to increase PIP3 levels leading to AKT activation, and of DYRK3 and LAMTOR1, both of which can sustain AKT phosphorylation via mTORC, indicating acquired resistance through bypassing inhibited PI3K-AKT signaling to rescue AKT. NXP900 reduced tumor growth rates in 5 of 9 PDX models. Kinases associated with sensitivity in the PDX models included SFKs (SRC, LYN, and FYN), and AKT, PTK2, PRKCZ, EGFR, SYK, and GSK3B, suggesting involvement of the PI3K-AKT pathway in responsiveness to NXP900. Based on tumor inhibition responses in the tested models, we estimated NXP900 response for our additional PDX models, predicting 39% (11/28) of patient tumors may respond. Conclusion: This study identified molecular markers linked to response to SFK inhibition, which could be utilized for patient selection for NXP900 treatment. Further studies are validating these findings and exploring combination therapies to address resistance mechanisms. Citation Format: Hendrien Kuipers, Danielle M. Carlson, Jack W. Sample, Erik Jessen, Dong-Gi Mun, Aushinie M. Abeynayake, Jennifer L. Tomlinson, Amro M. Abdelrahman, Nathan W. Werneburg, Binbin Li, Mitesh J. Borad, Mark J. Truty, Sumera I. Ilyas, Gregory J. Gores, Rory L. Smoot. Multiomic profiling identified biomarkers of response to selective Src family kinase inhibition in preclinical models of cholangiocarcinoma [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 5595.

Abstract Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) affects about 32% of adults worldwide and is projected to increase in many parts of the world. Liver cancer is a recognized complication of end-stage MASLD. An estimated 20% of patients with MASLD will progress to cirrhosis, a premalignant state in liver cancer evolution. Because MASLD is usually asymptomatic, its progression to cirrhosis can be difficult to detect early for timely intervention. There are currently no known biological markers for predicting cirrhosis risk in patients with MASLD, making it challenging to identify patients at risk of disease progression. The aim of this study was to identify plasma protein biomarkers that can predict future cirrhosis development in patients with MASLD. Methods: We performed a nested case-control study among patients with MASLD at baseline who later progressed to cirrhosis and control patients with MASLD at baseline who never progressed to cirrhosis, matched on age at MASLD diagnosis (± 1-year), sex, race, year of blood sample collection, and length of follow-up (± 1-year). An aptamer-based array (SOMAscan™) platform was used to measure over 7000 proteins in baseline plasma samples obtained from the participants. The study sample was split 70/30 for training and validation analyses. We identified plasma protein biomarkers significantly differentially expressed in the training sample, adjusting for multiple testing with Bonferroni-corrected p-values. The significant set of proteins from the training set was used for prediction modeling in the validation sample, computing prediction metrics (area under the curve [AUC], sensitivity, specificity, and accuracy). Results: A total of 64 MASLD to cirrhosis cases matched to 64 MASLD controls were included in the analysis. Six protein biomarkers (PTPRU, ATL2, MFAP4, C7, CSTN2, and COLEC11) were overexpressed in cases, compared to controls, in the training data. Prediction modeling of the six-protein biomarker panel in the validation sample yielded an AUC = 0.85, sensitivity = 0.72, specificity = 0.78, and accuracy = 0.75. Conclusions: We have identified a panel of six plasma protein biomarkers that predict risk of cirrhosis development in patients with MASLD. These proteins could serve as candidates for future mechanistic studies on MASLD progression to advanced liver disease. If validated in larger studies and with assays suitable for clinical laboratory testing (e.g., ELISA), these protein biomarkers could be useful clinically for cirrhosis risk prediction in MASLD patients, and hence those at risk of liver cancer, enabling timely surveillance or interventions to prevent disease progression. Citation Format: Pasang Sherpa, Sebastian M. Armasu, Jacob A. Frank, Irene K. Yan, Kirk J. Wangensteen, Tushar Patel, Samuel O. Antwi. Predicting cirrhosis risk in patients with metabolic dysfunction-associated steatotic liver disease [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 2335.

Abstract Background: Pancreatic cancer is a frequently fatal disease that is often diagnosed at a late stage associated with a poor prognosis and an increasing impact on cancer related mortality. Despite advances, chemotherapy remains the mainstem of therapeutic interventions for this disease and most of the currently identified molecular alterations are not currently targetable. Therefore, novel biomarkers and strategies are necessary to impact patient outcomes. Claudin-18.2 (CLDN18.2) is a splice variant of the Claudin 18 family and is a component of tight junctions, which seal the paracellular spaces of epithelial and endothelial cells. CLDN18.2 is frequently retained in malignant gastric tissue and overexpressed in pancreatic and gastroesophageal adenocarcinomas. CLDN18.2 overexpression at the message and protein levels has been observed in pre-clinical studies involving pancreatic cancer cell lines and in tumors from pancreatic cancer patients. The goal of this study was to obtain a deeper understanding of CLDN18.2 positivity and CLDN18.2 expression and the associated clinical prevalence, prognostic implications, patient clinical characteristics and relationship with other biomarkers in pancreatic ductal adenocarcinoma (PDAC) patient samples. Design: This was a single institution/reference laboratory based retrospective study including as many as 320 patients, in which CLDN18.2 positivity as defined by ≥ 75% of the tumor cells expressing moderate to strong membranous staining was examined. The goals were to evaluate CLDN18.2 in tumor samples by immunohistochemistry for prevalence in pancreatic adenocarcinoma patients. Claudin 18.2 expression was assessed by the Ventana (43-14A) Class I IVD that was purchased from Ventana/Roche Diagnostics. In addition to prevalence, CLDN18.2 was evaluated with respect to the clinicopathological features of patients, patient prognosis, adjusted for clinical covariables, response to treatments and relationship to patient demographics, tumor grade and disease status. Patient information has been obtained from electronic medical records and research database to establish clinical course (survival status, metastatic sites, etc.) along with patient demographics. Conclusions: CLDN18.2 is a novel potentially actionable biomarker in patients with advanced and metastatic pancreatic adenocarcinoma. This study provides important clinical information regarding CLDN18.2 expression in these patients that is important to consider when evaluating biomarkers in these patients. Funding for the study was provided by Astellas Pharma Global Development, Inc. Citation Format: Allison Kerper, Robert H. Getzenberg, Rondell P. Graham. Real world clinical characteristics of claudin 18.2 expression in patients with pancreatic adenocarcinoma [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 5915.

Background: Rare, functionally deleterious genetic variants have been implicated as having substantially larger effect sizes than common variants, potentially accounting for much of the missing heritability in lung cancer (LC). Over 25 years, the Genetic Epidemiology of LC Consortium (GELCC) has curated an invaluable resource of specimens and data from individuals with a strong family history of LC. Methods: Whole-genome and exome sequencing data were analyzed in 129 high-risk familial LC (FLC) families, defined as having two first-degree relatives or three or more second-degree relatives affected by LC (177 affected FLC and 309 unaffected relatives). The discovery focused on rare (allele frequency < 1% in gnomAD global population) and deleterious variations (missense, stop-gained, frameshift) enriched in FLC. Promising candidates were further external validated in 2,408 sporadic lung cancer (SLC) cases and 885 population controls from the International Lung Cancer Consortium. Results: We identified 168 variants with moderate-to-large effects on FLC risk, 100 of which were validated for SLC risk (Table 1 Table 1. Top 20 candidates Gene Rare (MAF < 1%), deleterious variants No. of variant carrier counts Odds Ratio, LC vs Control FLC | Relative | SLC | Control FLC+SLC SLC Oncogene ERBB3 / HER3 p.A1131T 3 | 1 | 2 | 0 35 15 JAK p.V651M 2 | 3 | 7 | 0 62 51 NOTCH3 p.R1560P 3 | 1 | 4 | 0 48 29 ROS1 p.N785X 6 | 4 | 10 | 0 110 74 USP6 p.R522 fs del 3 | 6 | 6 | 0 62 45 Tumor suppressor gene ATM p.L2332P 3 | 2 | 8 | 0 76 59 LZTS2 p.K458R 4 | 4 | 18 | 0 152 133 NPIPB13 p.V270 fs del 13 | 14 | 10 | 0 159 74 PARK2 / PRKN p.P153R 3 | 3 | 8 | 0 76 59 RB1 p.A525G 3 | 0 | 6 | 0 62 45 SLX4 p.S1716T 3 | 2 | 9 | 0 83 66 SYNE1 p.M6566I 2 | 0 | 7 | 0 62 52 TGFBRAP1 p.T301R 5 | 0 | 11 | 0 110 82 WNK1 p.K583 fs del 4 | 0 | 23 | 0 187 171 Other cancer-associated gene CFTR p.R74W 4 | 2 | 4 | 0 55 30 FLG p.R3404 fs del 7 | 2 | 4 | 0 69 30 LTN1 p.R349H 6 | 1 | 10 | 0 110 74 MLNR p.Q334 fs del 3 | 2 | 19 | 0 152 134 SLC39A11 p.R38Q 4 | 2 | 13 | 0 117 96 TTYH2 p.R493C 5 | 4 | 14 | 0 131 104 Dose effect of the top candidates No. candidates 0 variant allele 67 | 194 | 1911 | 834 reference reference 1 variant allele 50 | 66 | 363 | 50 3.5 (2.6 - 4.7) 3.2 (2.3 - 4.3) 2 variant alleles 15 | 18 | 62 | 1 32 (4.5 - 230) 27 (3.8 - 195) 3+ variant alleles 45 | 31 | 72 | 0 98 (6 - 1506) 62 (3.9 -1012) lists 20 top hits). Among these, 15 variants mapped to our previously identified lung cancer linkage locus at 6q23-25 (ROS1, PARK2, SYNE1). Others were enriched in oncogenes (ERBB3, JAK1, MET), tumor suppressor genes (ATM, BRCA2, RB1), and genes involved in the extracellular matrix (COL6A3, FLG, MUC5B). Importantly, individuals carrying more than two combinations of these variants exhibited exceptionally strong dose effects, with odds ratios (OR) exceeding 27. Conclusion: Our findings underscore the significant role of rare, high-penetrance variants in FLC etiology and highlight promising targets for early detection and personalized treatment. Future in-depth mechanistic studies are planned to evaluate the pathogenic effects of these specific alleles. Citation Format: Yanhong Liu, Claudio Pikielny, Xiangjun Xiao, Bo Peng, Yafang Li, Jinyoung Byun, Chao Cheng, Dakai Zhu, Spiridon Tsavachidis, Colette Gaba, Elena Kupert, Ellen L. Goode, Erin L. Crawford, Kristen Purrington, Marshall Anderson, Michael Cole, Paul Brennan, Geoffrey Liu, James McKay, John K. Field, Rayjean J. Hung, David C. Christiani, Diptasri Mandal, James C. Willey, Ann Schwartz, Joan Bailey-Wilson, Susan M. Pinney, Christopher I. Amos. High-penetrance rare variants underlying familial lung cancer risk: Insights from the Genetic Epidemiology of Lung Cancer Consortium [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 3815.

Abstract Background: Mutant BRAF(V600E) is present in 8-12% of human colorectal cancers (CRCs) and is associated with treatment resistance and poor survival. Targeted therapy with inhibitors of BRAF and EGFR is associated with only an incremental survival benefit. Methods: We studied the novel CDK2/CDK9 inhibitor, fadraciclib, alone and in combination with the BRAF inhibitor encorafenib on isogenic CRC cells with two, one, or no BRAFV600E alleles (RKO+/+, A19+/-, T29-/-). Analysis of apoptosis, colony formation, and the cell cycle was performed. The effect of drug treatment on growth of tumor xenografts was determined in a zebrafish model. Results: Fadraciclib induced apoptosis and inhibited colony formation in a gene dose-dependent manner. Its growth inhibitory effect when combined with encorafenib was synergistic. Mechanistically, fadraciclib suppressed the expression of pro-survival MCL-1 and decreased the phosphorylation of RNA polymerase II indicating suppression of RNA transcription. Fadraciclib also impaired Rb phosphorylation and promoted a DNA damage response indicated by the cleavage of PARP, pH2AX (ser139), and activation of p53. Drug treatment was associated with a greater suppression of Rb phosphorylation, cell cycle inhibition, and apoptosis in RKO+/+ versus A19+/- and T29-/- cells. In a zebrafish tumor xenograft model, fadraciclib plus encorafenib significantly reduced the tumor xenograft size concurrent with increased caspase-3 activation. Conclusion: Fadraciclib plus encorafenib potently induced apoptosis and synergistically suppressed tumor cell growth in a gene dose-dependent manner in BRAFV600E CRC cells, and exerted anti-tumor effects in a tumor xenograft model. These data suggest a novel therapeutic strategy in this CRC subtype. Citation Format: Md Mohiuddin, Vanda Póvoa, Rita Fior, Frank A. Sinicrope. Novel CDK2/CDK9 inhibitor fadraciclib targets cell survival and DNA damage pathways and synergizes with encorafenib in human colorectal cancer cells with BRAF(V600E). [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 1682.

Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense, collagen-rich stroma that impedes drug delivery. We investigated how iRGD-mediated nanoparticle delivery modifies collagen architecture using humanized mouse models. Computational analysis of Picro-Sirius Red-stained whole-slide images (WSIs) using curvelet transform-based fiber extraction method (CT-FIRE) was performed to quantitatively examine changes in collagen features, thereby understanding treatment-induced alterations in the tumor microenvironment (TME). Methods: Humanized PDAC mice were prepared with either the human PANC-1 cell line or 0779 primary human PDAC cells and treated with or without iRGD monotherapy for two months (n=12). Primary tumors were sectioned and stained with Picro-Sirius Red to visualize collagen structures. WSIs of Picro-Sirius Red-stained tissues were analyzed with CT-FIRE to extract six morphological features of collagen, including average fiber length, waviness, and density to capture structural changes. WSIs were divided into 256×256 pixel tiles with consistent sampling through bootstrapping, followed by permutation testing for statistical validation (1,000 permutations, p<0.01). Results: Computational analysis revealed significant iRGD-induced collagen remodeling with quantifiable changes in key structural and morphological features. Permutation testing showed that, compared to controls, average fiber length decreased by 3.27% (p<0.01), waviness reduced by 3.25% (p<0.01), and density diminished by 36.3% (p<0.01), compared to controls. The structural changes were more notable in 0779-derived tumors compared to PANC-1, with reductions in average fiber length (1.03%, p<0.01), waviness (8.78%, p<0.01), and collagen density (24.27%, p<0.01), demonstrating cell-line dependent stromal remodeling. Conclusions: Our findings suggest that long-term iRGD therapy alters collagen morphology in PDAC. Further investigation is warranted to understand how these alterations contribute to enhanced penetration of drugs and immune cells observed in iRGD-treated PDAC tumors. The observed cell-line dependent variations in stromal remodeling suggest tumor heterogeneity influences treatment response, highlighting the potential for personalized therapeutic approaches in stromal-rich tumors like PDAC. Citation Format: Yoon Ho Choi, Minji Kim, Hotaka Kawai, Yukihito Kuroda, Norio Miyamura, Seock-Jin Chung, Kazuki N. Sugahara, Tae Hyun Hwang. Altered collagen morphology in pancreatic cancer treated with the iRGD tumor-penetrating peptide [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 2698.

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) exhibits a complex, immunosuppressive tumor immune microenvironment (TIME), necessitating molecular-level understanding to identify therapeutic targets. We investigated how iRGD peptide therapy remodels the immunosuppressive TIME to an immune-favorable state using single-cell spatial molecular analysis. Methods: Single-cell level in situ molecular imaging was performed using Xenium analyzer with 5K gene panel on tumor samples from humanized PDAC mice (n=7) treated with iRGD monotherapy (n=3) or control (n=4), enabling comprehensive spatial molecular characterization of the TIME. Results: iRGD therapy significantly transformed the immunosuppressive TIME to an immune-favorable state through T-cell composition remodeling. We observed increased populations of CD4+ memory T cells, CD4+ helper T cells, and cytokine-secreting effector T cells, indicating enhanced immune memory and effector functions. Concurrent decreases in regulatory T cells and activated CD4+ T cells reflected reduced immune suppression. Additionally, decreased TGF-β signaling in the iRGD cohort suggested TGF-β antagonism as a mechanism for overcoming immunosuppression. Conclusions: iRGD therapy effectively converted the immunosuppressive PDAC microenvironment to an immune-favorable state by enhancing beneficial T cell populations and reducing immunosuppression through TGF-β pathway modulation. These findings support previous work by Kuroda et al. and provide mechanistic rationale for the ongoing iRGD-based immunotherapy clinical trial (iLSTA:ACTRN12623000223639).Acknowledgments: We thank DeepL for the English language editing. Citation Format: Minji Kim, Yoon Ho Choi, Hotaka Kawai, Yukihito Kuroda, Norio Miyamura, Kazuki N. Sugahara, Tae Hyun Hwang. iRGD peptide therapy transforms immunosuppressive microenvironment to immune-favorable state in pancreatic ductal adenocarcinoma [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 2701.

Abstract Recurrence after surgery remains a major cause of failure in head and neck squamous cell carcinoma (HNSCC), particularly for HPV-negative patients whose 2-year failure rate is > 50%. There is unmet need for an accurate diagnostic test that predicts risk of recurrence prior to adjuvant therapy selection. We evaluated ctDNA in lymphatic exudate (“lymph”) collected via surgical drains at 24 hours to detect molecular residual disease (MRD) and compared its performance to plasma and adverse pathology features. Lymph, plasma and blood were collected from 76 HPV- HNSCC patients 24 hours after surgery. Tumor tissue was collected at surgery. 73 patients passed QC. Samples were sequenced using a 699-gene custom panel to a median of 6322x (lymph and plasma cfDNA) or 533x (tumor and blood genomic DNA). Tumor variants were directly genotyped in lymph and plasma using a tumor-informed pipeline. MRD status was determined using a calibrated cutoff based on mean variant allele fraction. Wilcoxon signed-rank test was used for comparisons. Kaplan-Meier estimator with log-rank test and Cox proportional hazards model were used for survival analysis. We previously demonstrated that 24 hour postoperative lymph ctDNA detects recurrence in HPV(-) HNSCC across two independent multi-site cohorts and by orthogonal sequencing approaches (sensitivity (SN) = 72%, specificity (SP) = 65%, p = 0.003, hazard ratio (HR) = 3.1, n = 73). When compared to other data available at this early time point (pathology and 24 hour postoperative plasma), lymph ctDNA outperformed each for recurrence detection (extranodal extension (ENE, p = 0.30), lymphovascular invasion (p = 0.02), perineural invasion (p = 0.38), positive lymph nodes (p = 0.03), plasma (p = 0.8)). We next evaluated lymph ctDNA in a critical subpopulation: patients considered intermediate risk by pathology (negative for ENE or margins but with one or more other adverse pathologic feature). Current NCCN guidelines recommend radiotherapy and to “consider systemic therapy” for these patients. Lymph ctDNA accurately stratified recurrence in this group with high sensitivity (SN = 88%, SP = 69%; P = 0.013, HR = 9.1, n = 24). Within this cohort, 77% of patients who received RT alone and later recurred were positive for lymph ctDNA at 24 hours, suggesting an opportunity to use molecular data in concert with pathology to identify patients who may benefit from adjuvant treatment intensification. Postoperative lymph represents a novel proximal analyte for MRD detection in HPV- HNSCC designed specifically for use in the immediate post-surgical window when adjuvant therapy decisions must be made. Lymph ctDNA is significantly associated with recurrence and outperforms both time-matched plasma and pathology. Accurate MRD identification at this early timepoint has the potential to augment traditional pathology and personalize adjuvant treatment paradigms in HPV-negative HNSCC. Citation Format: Seka Lazare, Zhuosheng Gu, Noah Earland, Adam Harmon, Maciej Pacula, Megan Long, Ashley Tellis, Damion Whitfield, Adam Benson, Lucien Khalil, Robert L. Ferris, Marra Francis, Aadel A. Chaudhuri, Jose P. Zevallos, Wendy Winckler. Postoperative lymphatic exudate in HPV-negative head and neck cancer detects recurrence prior to adjuvant treatment decisions [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 1946.