Pancreatic cancer represents one of the most lethal tumors, characterized by an immunosuppressive microenvironment and a lack of cytotoxic immune cell infiltrates, which confer resistance to immunotherapy. Here, we demonstrate that deletion of poly(ADP-ribose) polymerase 2 (PARP2) in a Myc -driven mouse model of pancreatic cancer delays tumor progression and increases survival. Mechanistically, PARP2 loss induces enrichment of pathways associated with genomic instability and replicative stress, leading to increased γH2AX, chromosomal instability, and micronuclei accumulation. In addition to these tumor-intrinsic effects, PARP2 deletion reshapes the tumor microenvironment, promoting infiltration of cytotoxic T and natural killer cells while reducing immunosuppressive cell populations, enhancing antitumor cytotoxicity. These findings are recapitulated in a Kras G12D -driven orthotopic pancreatic ductal adenocarcinoma model. Collectively, our data support selective PARP2 inhibition as a promising therapeutic strategy for pancreatic cancer by impairing genome integrity and boosting antitumor immune response, thereby opening potential avenues for combating this devastating disease.

High-fat diet (HFD) and obesity are increasingly recognized as risk factors of pancreatic ductal adenocarcinoma (PDAC), yet the mechanisms by which dietary fat contribute to oncogenic transformation remain elusive. Using an inducible acinar-specific KrasG12V / Trp53 -loss genetically-engineered mouse model of PDAC, we established early- and late-onset protocols to assess age-dependent susceptibility to HFD. Specifically, HFD accelerated tumorigenesis with poorer prognosis in early-onset mice and, strikingly, enabled full PDAC development in late-onset adult mice otherwise resistant to oncogenic transformation. Tumors arising under HFD activated a distinct transcriptional and epigenetic state enriched in pathways or genes related to stemness, plasticity, and metastatic competence, which was maintained even in tumor-derived cell lines. Mechanistically, fatty acid-educated macrophages secreted the cathelicidin antimicrobial peptide (CAMP), activating P2X purinoceptor 7 (P2RX7) signaling in tumor cells to drive a highly plastic, immune-evasive phenotype reinforced by the expression of the peptidoglycan recognition protein 1 (PGLYRP1), further shielding tumor cells from macrophage phagocytosis. Functionally, HFD-induced tumors displayed enhanced metastatic potential independent of host context. Analysis of 164 human PDAC samples revealed that elevated body-mass index (BMI) was associated to a conserved CAMP-P2RX7-CXCR4 signature, maintained despite weight loss during disease progression. Together, these findings uncover a diet-imprinted macrophage-tumor cell circuit that promotes transformation and accelerates PDAC progression, positioning it as a therapeutic vulnerability in obesity-associated pancreatic cancer. ### Competing Interest Statement The authors have declared no competing interest. Asociación Española Contra el Cáncer, https://ror.org/00gxct719, PRDMA246123GALV, POSTD258037LÓPE, LABAE223389SANC Asociación Cancer de Pancreas, IX Carmen Delgado/Miguel Pérez-Mateo grant European Research Council, ERC-AG/695566-THERACAN Centro de Investigación Biomédica en Red de Cáncer, CB21/12/00121 AIRC, IG 26201, IG 32351 PNRR Program, PNRR-MCNT2-2023-12377229 NEXTGENERATION-EU, CN00000013 European Regional Development Fund, PID2024-159192OB-I00 Pancreatic Cancer UK, 06/Q0512/106 Instituto de Salud Carlos III, PT20/0045, PT23/00098

Pancreatic ductal adenocarcinoma (PDAC) has one of the lowest cancer survival rates. Recent studies using RAS inhibitors have opened the door to more efficacious therapies, although their beneficial effect is still limited mainly due to the rapid appearance of tumor resistance. Here, we demonstrate that genetic ablation of three independent nodes involved in downstream (RAF1), upstream (EGFR), and orthogonal (STAT3) KRAS signaling pathways leads to complete and permanent regression of orthotopic PDACs induced by KRAS/TP53 mutations. Likewise, a combination of selective inhibitors of KRAS (RMC-6236/daraxonrasib), EGFR family (afatinib), and STAT3 (SD36) induced the complete regression of orthotopic PDAC tumors with no evidence of tumor resistance for over 200 d posttreatment. This combination therapy also led to significant regression of genetically engineered mouse tumors as well as patient-derived tumor xenografts (PDX) in the absence of tumor relapses. Of importance, this combination therapy was well tolerated. In sum, these results should guide the development of new clinical trials that may benefit PDAC patients.

OBJECTIVE:We evaluated the implementation of a pilot patient-ambassador program designed to facilitate peer-to-peer discussion and education about gynecologic oncology (GYO) clinical trials among trial-naïve patients. METHODS:We conducted a mixed-methods interventional behavioral study at an NCI designated comprehensive cancer center to assess a program initiating peer conversations about GYO clinical trials. From Feb-Oct 2024, patients who had previously participated in GYO clinical trials were recruited as ambassadors. Ambassadors completed a structured educational curriculum and were paired with 5-8 trial-naïve mentees with high-risk or advanced gynecologic cancers. Implementation outcomes included acceptability, feasibility, net promotor score, clinical trials knowledge, confidence discussing trials, and perception of trials. Qualitative analyses of recorded chats, and ambassador feedback were also performed. RESULTS:Three ambassadors and 20 mentees completed the program, generating 20 "chats" from 266 eligible mentees. At baseline, 90% of mentees had heard of clinical trials and 75% reported somewhat or very positive perceptions. Post chat, 90% reported somewhat or very positive perceptions, 85% felt the chat changed their view of trials, and 95% felt confident to ask their oncology provider about trials. Although overall survey-based knowledge did not improve, 95% reported the chats were educational and addressed concerns. Acceptability, feasibility, and program promotion were high. Implementation challenges included emotional strain on ambassadors, mismatched expectations, and variability in discussing recruitment of diverse populations. CONCLUSIONS:This pilot patient-ambassador program is a feasible and acceptable intervention that improved patient confidence in discussing clinical trials with providers.

Abstract Chromosomal instability (CIN) describes the set of processes that generate numerical and structural DNA changes that typically operate during tumourigenesis. High-resolution readouts of DNA changes can be achieved using whole-genome sequencing (WGS) and the distinct patterns of copy number aberrations seen in these data can then be used to infer which type of CIN operated on the genome1-3. However, this static readout only provides evidence of historical or past CIN, as bulk WGS lacks the resolution needed to identify ongoing CIN that is actively shaping genome evolution. To address this limitation, we have developed a computational framework that leverages single-cell whole-genome sequencing (scWGS) to identify and quantify ongoing CIN by detecting cell-unique copy number alterations and probabilistically mapping them to known CIN signatures2. We assessed performance by generating in vitro models with 4 types of induced CIN via CRISPR knockout of DNA repair genes or drug perturbation, and correctly identifying the induced-CIN type in each case. Applied to near-diploid BRCA1/2-deficient hTERT-RPE1 models, we show that only single-cell, and not bulk, WGS can reveal ongoing homologous recombination deficiency (HRD) scars, enabling accurate identification of sensitivity to PARP inhibitors. In 4 pancreatic cancer organoids treated with platinum-based chemotherapy, ongoing HRD scars correctly identified the most sensitive organoid, which was misclassified as resistant using bulk WGS. Analysis of scWGS from 8 triple-negative breast cancers further reveal that impaired non-homologous end joining (NHEJ) is associated with subclonal diversification. Consistent with this observation, activity levels of CX10 (a CIN signature linked to NHEJ impairment1) was significantly higher in 119 metastatic TNBCs compared with 60 primary tumours (p-value=0.0085, Wilcoxon test), suggesting a link between defective NHEJ, subclonal evolution and increased metastatic potential. Together, these results show that our framework reveals treatment-relevant, recent CIN processes undetected by bulk sequencing, and it offers a robust tool for dissecting tumour evolution. Our study supports expanding biomarker-guided therapies by targeting active CIN rather than historical genomic scars. References: 1Macintyre et al. Nat Genetics, 2018; 2Drews et al. Nature, 2022; 3Thompson et al. Nat Genetics, 2025 Citation Format: Barbara Hernando, Blas Chaves-Urbano, Maria Escobar-Rey, Alice Cadiz, Angel Fernandez-Sanroman, Marina Torres, Sara Barrambana, Carmen G. Lechuga, Carmen Guerra, Mariano Barbacid, Maria Garcia-Perez, Patricia G. Santamaria, Geoff Macintyre. Quantifying ongoing chromosomal instability using single-cell whole-genome sequencing [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 4698.

Supplementary Table 2. Representativeness of Study Participants

ABSTRACTBackground and MethodsColorectal cancer (CRC) treatment can influence health‐related quality of life (HRQOL). This study examined HRQOL among older adults undergoing CRC treatment, and the conditional effects of race, ethnicity, and primary language. We conducted a retrospective cohort study of Medicare Advantage enrollees ≥ 65 years old who completed the Medicare Health Outcomes Survey (MHOS) (2016−2020). The exposure group answered “Yes” to the current CRC treatment and the control group answered “No.” The primary outcomes were physical component summary (PCS) and mental component summary (MCS) scores. Conditional effects by race and ethnicity were analyzed using interaction terms.ResultsAmong 184 486 adults, 676 (0.4%) reported current CRC treatment. Those receiving treatment had significantly lower PCS scores (β coefficient −1.98, p < 0.001) and lower MCS scores (β coefficient −0.81, p = 0.018), compared to nontreatment. In the treatment group, Hispanic respondents and Spanish speakers had higher PCS scores (β coefficient 1.96, p = 0.019 and 3.19, p = 0.023, respectively), and respondents identifying as American Indian or Alaska Native had higher MCS scores (β coefficient 8.72, p = 0.016).ConclusionIndividuals receiving CRC treatment exhibit worse HRQOL. Outcomes differed by race and ethnicity. This study suggests the need to invest in targeted interventions to improve overall HRQOL during treatment for CRC.

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths, with a five-year survival rate around 12%. In PDAC, cancer-associated fibroblasts (CAFs) play a vital role in promoting the desmoplastic and immunosuppressive tumor microenvironment (TME), and have emerged as relevant cancer targets. CAFs produce intratumoral hyaluronic acid (HA) whose accumulation induces high interstitial fluid-pressure (IFP) which can interfere with drug delivery. Moreover, HA has been linked with tumor escape from immune surveillance. Systemic administration of Hyaluronidase, via the PEGPH20 formulation, has reduced stromal HA, normalized IFP, and consequently improved the efficiency of the cytotoxic compound, gemcitabine, leading to increased survival in mice. In this study we have decided to eliminate HA by a different approach involving its synthesis rather than inducing its degradation. To this end, we have genetically targeted the three genes encoding HA synthases (Has1, 2, 3). Has1 and Has3 null alleles were generated by CRISPR technology in mouse embryos since they are nor essential for embryonic development. To eliminate Has2, we used existing conditional Has2lox alleles (Matsumoto et al. 2019, PMID XXXX) along an inducible allele, Rosa26-CreERT2, encoding an inducible Cre-ERT2 recombinase to allow the systemic ablation of the conditional Has2lox alleles in adult mice upon exposure to a Tamoxifen-containing (TAM) diet. These alleles were added to the standard KPF strain (KRas +/FSFG12V;P53F/F;Pdx1-FlpO) to determine the effect of HA elimination in tumor-bearing mice. Exposure of these adult animals to the TMA diet induced significant levels of HA depletion leading to reprogramming of tumoral, stromal and immune cells leading to significantly reduced tumor progression. Tumor cells were more differentiated as illustrated by higher expression of cytokeratin19 and additional epithelial cell adhesion molecules. Furthermore, these tumor cells displayed reduced proliferative capacity, mor limited EMT, migration and invasive capacity. Interestingly, they also exhibited upregulated Kras expression. At the stroma level, we observed less fibrotic tissue, decreased collagen deposition, reduced CAFs activation,and changes in the CAF populations, with high content of iCAFs (Inflammatory CAFs) and very low content in myCAFs (Myofibroblast CAFs). More importantly, we also observed infiltration of CD8+ T cells. Notably, HA depletion enhanced the efficacy of gemcitabine, the anti-CTLA-4 and the panras inhibitor darasonrasib, either alone or in combination of anti-CTLA-4. In summary, HA depletion in PDAC produced multiple changes at different levels that opens up new opportunities for therapeutic interventions. Pian Sun, Ángeles Durán, Federico Virga, María Diaz-Meco, Jorge Moscat, Carmen Guerra, Mariano Barbacid. Targeting hyaluronic acid in pancreatic ductal adenocarcinoma uncovers novel therapeutic opportunities [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research—Emerging Science Driving Transformative Solutions; Boston, MA; 2025 Sep 28-Oct 1; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl_3):Abstract nr B031.

Pancreatic Ductal Adenocarcinoma (PDAC) belongs to the types of cancer with the highest lethality. It is also remarkably chemoresistant to the few available cytotoxic therapeutic options. PDAC is characterized by limited mutational heterogeneity of the known driver genes, KRAS, CDKN2A, TP53, and SMAD4, observed in both early-stage and advanced tumors. In this review, we summarize the two proposed models of genetic evolution of pancreatic cancer. The gradual or stepwise accumulated mutations model has been widely studied. On the contrary, less evidence exists on the more recent simultaneous model, according to which rapid tumor evolution is driven by the concurrent accumulation of genetic alterations. In both models, oncogenic KRAS mutations are the main initiating event. Here, we analyze the emerging topic of KRAS allelic imbalances and how it arises during tumor evolution, as it is often detected in advanced and metastatic PDAC. We also summarize recent evidence on how it affects tumor biology, metastasis, and response to therapy. To this extent, we highlight the necessity to include studies of KRAS allelic frequencies in the design of future therapeutic strategies against pancreatic cancer.

Supplementary Table 3. Genetic variant detected in the custom gene panel through whole exome sequencing.

The KRAS oncogene has been associated with many types of cancer, including pancreatic, lung, and colorectal. For decades, its gene products were thought to be undruggable. However, during the last decade, a large battery of KRAS inhibitors selective against specific mutations (KRASG12C and KRASG12D), panKRAS inhibitors active against all KRAS isoforms, or even panRAS inhibitors, capable of inhibiting the three members of the RAS family, have been developed. In mice, the Kras locus is essential for embryonic development and can sustain adult homeostasis in the absence of Hras and Nras expression. Thus, we considered of interest to interrogate the role of the Kras locus in an experimental system to generate potentially relevant information regarding the use of panKRAS or panRAS inhibitors in the clinic. Here, we report that systemic ablation of Kras expression in adult mice does not induce significant changes in overall survival, body weight, glucose levels, metabolic profile, or heart function. In contrast, flow cytometry and histopathological analyses of organs such as blood, bone marrow, and spleen showed a significant increase of the myeloid lineage leading to myelomonocytic metaplasia. In this context, replacement of the KRAS isoforms by HRAS is sufficient to maintain adult homeostasis, suggesting that the unique properties of the Kras locus are primarily due to its pattern of expression rather than to the activity of its gene products.

10539 Background: Colorectal cancer (CRC) screening remains suboptimal, particularly in racially diverse and low-income populations. Machine learning (ML) algorithms trained on routine electronic health record (EHR) data may accurately predict CRC risk. Further, patient navigation programs can address screening barriers such as lack of transportation access and low health literacy around colonoscopy preparation. We tested the impact of an intervention combining ML-based risk stratification and an evidence-based CRC screening navigation program on CRC screening rates and outcomes. Methods: This prospective nonrandomized controlled study (NCT05383976) was conducted at a large academic health system, enrolling adults over 50 years of age and at average-risk of CRC. All adults resided in Persistent Poverty zip codes (defined by the US Census Bureau) in the Philadelphia metro area, were attributed to a primary care physician (PCP), and had a colonoscopy order that had not been completed within the past 6 months. We adapted a validated ML algorithm that was previously trained on 22 variables – including age, sex, and longitudinal complete blood counts – to predict CRC risk. Patients enrolled in the intervention arm were prioritized by the ML algorithm for a structured navigation program, including risk-targeted phone-based education, appointment facilitation, transportation support, and mailed FIT tests. A concurrent control cohort received navigation but was not prioritized by the ML algorithm. Adjusted logistic regression models assessed the intervention’s impact on the co-primary outcomes of (1) CRC screening completion (colonoscopy or FIT), and (2) positive screening result, defined as precancerous adenoma (sessile serrated, inflammatory, villous, malignant) and/or positive FIT. Results: 382 patients were enrolled (199 intervention, 183 control). Among intervention patients, 71.4% were reached via phone and 66.4% scheduled screening, with 26.2% and 17.6% completing colonoscopy and FIT, respectively (see Table). Screening completion was similar for intervention vs. control (46.2% vs. 43.2%; adjusted OR 1.02, 95% CI 0.67-1.56, p=0.93). For intervention vs. control, precancerous adenoma detection was 8.5% vs. 5.2% (aOR 2.43, 95% CI 0.48–12.3, p=0.57) and tubular adenoma detection was 35.6% vs. 25.0%. Conclusions: ML-informed navigation was feasible, did not increase screening engagement, and marginally increased rates of precancerous and tubular adenoma detection. Refinements in ML risk stratification and enhanced navigator outreach may maximize impact. Clinical trial information: NCT05383976 . Navigator services provided in intervention group. Number of telephone calls to outreach 1 81 (40.7%) 2 34 (17.1%) 3+ 27 (13.5%) Prep letter sent 11 (7.7%) Prep kit sent 24 (16.9%) Colonoscopy/FIT education 27 (19.0%) Transportation arrangement 8 (5.6%)

Supplementary Table 4. Preclinical model recommendation

Summary: Adapted excerpts from the 15th edition of the annual American Association for Cancer Research Cancer Progress Report (https://cancerprogressreport.aacr.org/progress/) to the US Congress and the public highlight significant strides made possible through medical research, much of which is supported by federal investments in the NIH, NCI, FDA, and Centers for Disease Control and Prevention.

The small GTPase Ras is an intracellular signaling hub required for long-term potentiation (LTP) in the hippocampus and for memory formation. Genetic alterations in Ras signaling (i.e., RASopathies) are linked to cognitive disorders in humans. However, it remains unclear how Ras controls synaptic plasticity, and whether different Ras isoforms play overlapping or distinct roles in neurons. Using genetically modified mice, we show here that H-Ras (the most abundant isoform in the brain) does not promote LTP, but instead long-term depression mediated by metabotropic glutamate receptors (mGluR-LTD). Mechanistically, H-Ras is activated locally in spines during mGluR-LTD via c-Src, and is required to trigger Erk activation and de novo protein synthesis. Furthermore, H-Ras deletion impairs object recognition as well as social and spatial memory. Conversely, K-Ras is the isoform specifically required for LTP. This functional specialization correlates with a differential synaptic distribution of the two isoforms H-Ras and K-Ras, which may have important implications for RASopathies and cognitive function.