We have shown that KRAS–TP53 genomic coalteration is associated with immune-excluded microenvironments, chemoresistance, and poor survival in pancreatic ductal adenocarcinoma (PDAC) patients. By treating KRAS–TP53 cooperativity as a model for high-risk biology, we now identify cell-autonomous Cxcl1 as a key mediator of spatial T-cell restriction via interactions with CXCR2+ neutrophilic myeloid-derived suppressor cells in human PDAC using imaging mass cytometry. Silencing of cell-intrinsic Cxcl1 in LSL-KrasG12D/+;Trp53R172H/+;Pdx-1Cre/+(KPC) cells reprograms the trafficking and functional dynamics of neutrophils to overcome T-cell exclusion and controls tumor growth in a T cell–dependent manner. Mechanistically, neutrophil-derived TNF is a central regulator of this immunologic rewiring, instigating feed-forward Cxcl1 overproduction from tumor cells and cancer-associated fibroblasts (CAF), T-cell dysfunction, and inflammatory CAF polarization via transmembrane TNF–TNFR2 interactions. TNFR2 inhibition disrupts this circuitry and improves sensitivity to chemotherapy in vivo. Our results uncover cancer cell–neutrophil cross-talk in which context-dependent TNF signaling amplifies stromal inflammation and immune tolerance to promote therapeutic resistance in PDAC. Significance: By decoding connections between high-risk tumor genotypes, cell-autonomous inflammatory programs, and myeloid-enriched/T cell–excluded contexts, we identify a novel role for neutrophil-derived TNF in sustaining immunosuppression and stromal inflammation in pancreatic tumor microenvironments. This work offers a conceptual framework by which targeting context-dependent TNF signaling may overcome hallmarks of chemoresistance in pancreatic cancer. This article is highlighted in the In This Issue feature, p. 1275

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a KRAS-driven inflammatory program and a desmoplastic stroma, which contribute to the profoundly chemoresistant phenotype. The tumor stroma contains an abundance of cancer-associated fibroblasts (CAF), which engage in extensive paracrine cross-talk with tumor cells to perpetuate protumorigenic inflammation. IL1α, a pleiotropic, tumor cell–derived cytokine, plays a critical role in shaping the stromal landscape. To provide insights into the molecular mechanisms regulating IL1A expression in PDAC, we performed transcriptional profiling of The Cancer Genome Atlas datasets and pharmacologic screening in PDAC cells and identified p38α MAPK as a key positive regulator of IL1A expression. Both genetic and pharmacologic inhibition of p38 MAPK significantly diminished IL1α production in vitro. Chromatin- and coimmunoprecipitation analyses revealed that p38 MAPK coordinates the transcription factors Sp1 and the p65 subunit of NFκB to drive IL1A overexpression. Single-cell RNA sequencing of a highly desmoplastic murine PDAC model, Ptf1aCre/+; LSL-KrasG12D/+; Tgfbr2flox/flox (PKT), confirmed that p38 MAPK inhibition significantly decreases tumor cell–derived Il1a and attenuates the inflammatory CAF phenotype in a paracrine IL1α-dependent manner. Furthermore, p38 MAPK inhibition favorably modulated intratumoral immunosuppressive myeloid populations and augmented chemotherapeutic efficacy to substantially reduce tumor burden and improve overall survival in PKT mice. These findings illustrate a cellular mechanism of tumor cell–intrinsic p38-p65/Sp1-IL1α signaling that is responsible for sustaining stromal inflammation and CAF activation, offering an attractive therapeutic approach to enhance chemosensitivity in PDAC. Significance: Inhibition of p38 MAPK suppresses tumor cell–derived IL1α and attenuates the inflammatory stroma and immunosuppressive tumor microenvironment to overcome chemotherapeutic resistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a significant contributor to cancer-related morbidity and mortality, and it is known for its resistance to conventional treatment regimens, including chemotherapy and immune checkpoint blockade (ICB)-based therapies. We have previously shown that Urolithin A (Uro A), a gut microbial metabolite derived from pomegranates, can target and inhibit KRAS-dependent PI3K/AKT/mTOR signaling pathways to overcome therapeutic resistance and improve survival in PDAC. However, the effect of Uro A on the tumor immune microenvironment and its ability to enhance ICB efficacy has not been explored. This study demonstrates that Uro A treatment reduces stromal fibrosis and reinvigorates the adaptive T-cell immune response to overcome resistance to PD-1 blockade in a genetically engineered mouse model (GEMM) of PDAC. Flow cytometric–based analysis of Uro A-treated mouse tumors revealed a significant attenuation of immunosuppressive tumor-associated M2-like macrophages with a concurrent increase in the infiltration of CD4+ and CD8+ T cells with memory-like phenotype along with reduced expression of the exhaustion-associated protein, PD-1. Importantly, the combination of Uro A treatment with anti-PD-1 immunotherapy promoted enhancement of the antitumor response with increased infiltration of CD4+ Th1 cells, ultimately resulting in a remarkable improvement in overall survival in GEMM of PDAC. Overall, our findings provide preclinical evidence for the potential of Uro A as a novel therapeutic agent to increase sensitivity to immunotherapy in PDAC and warrant further mechanistic exploration in preclinical and clinical studies. Significance: Immunotherapeutic agents are ineffective against pancreatic cancer, mainly due to the immunosuppressive tumor microenvironment and stromal desmoplasia. Our current study demonstrates the therapeutic utility of a novel gut microbial metabolite, Uro A, to remodel the stromal-immune microenvironment and improve overall survival with anti-PD-1 therapy in pancreatic cancer.

ATM (ataxia telangiectasia mutated) kinase is a central mediator of the DNA damage response (DDR), with established roles in maintaining genomic integrity in response to genotoxic insults. Both germline and somatic alterations in ATM occur frequently in tumors, with pathogenic variants affecting an estimated 1 in 100 individuals worldwide. Emerging evidence has shown its utility as a biomarker for therapeutic sensitivity. ATM-deficient tumors exhibit increased sensitivity to radiotherapy, chemotherapy and present opportunities for synthetic lethality approaches. Notably, ATM loss sensitizes tumors to ATR and PARP inhibitors. This review summarizes the structure and function of ATM kinase and its interacting partners, while addressing critical knowledge gaps in recently described rationale for drug combinations that induce selective synthetic lethality in tumors cells. We examine how these approaches can be leveraged to improve standard chemotherapeutic and immunotherapeutic treatments in cancer. Additionally, we highlight the key preclinical and clinical studies evaluating ATM as a predictive biomarker and discuss its evolving role in precision oncology.

BACKGROUND: Advances in genetic sequencing technologies, including somatic next-generation sequencing and circulating tumor DNA assays, have significantly impacted the management of rectal cancer. However, the clinical implications of these technologies remain incompletely understood. OBJECTIVE: To evaluate patterns and clinical utility of genetic sequencing among patients with rectal cancer. DESIGN: Retrospective cohort analysis from a prospectively maintained institutional registry. SETTING: Single National Cancer Institute–designated cancer center. PATIENTS: A total of 251 patients diagnosed with rectal cancer between January 2017 and April 2024 who underwent genetic testing. INTERVENTIONS: Somatic tumor sequencing and circulating tumor DNA analysis. MAIN OUTCOME MEASURES: Response to total neoadjuvant therapy, local recurrence, and distant metastasis. RESULTS: Genetic testing utilization increased substantially from 2017 to 2024, with somatic next-generation sequencing testing rising from 3% to 33% and circulating tumor DNA from 2% to more than 45%. Tumor mutational burden did not correlate significantly with response to total neoadjuvant therapy, recurrence, or metastasis. Mutation profiles across carcinogenesis pathways showed no significant differences between complete responders and those with residual disease after adjustment ( p = 0.145). After total neoadjuvant therapy, circulating tumor DNA positivity strongly correlated with residual disease (sensitivity 76.5%, specificity 82.4%; p = 0.0016), with tumor-agnostic circulating tumor DNA assays demonstrating significantly higher sensitivity than tumor-informed tests (100% vs 50%, p = 0.03). LIMITATIONS: Retrospective design, potential selection bias, single-center data. CONCLUSIONS: Despite increasing adoption, somatic next-generation sequencing alone lacks clear prognostic or predictive utility for rectal cancer management. In contrast, circulating tumor DNA testing demonstrated substantial promise for assessing response to total neoadjuvant therapy, particularly using tumor-agnostic platforms. Further prospective studies are needed to refine clinical guidelines and fully integrate these genetic technologies into rectal cancer care. See Video Abstract . UN MUNDO FELIZ: ANÁLISIS DE LA EXPERIENCIA CLÍNICA INICIAL CON LA SECUENCIACIÓN MOLECULAR EN EL TRATAMIENTO DEL CÁNCER RECTAL: ANTECEDENTES: Los avances en las tecnologías de secuenciación genética, incluyendo la secuenciación somática de última generación y los ensayos de ADN tumoral circulante, han tenido un impacto significativo en el tratamiento del cáncer rectal. Sin embargo, las implicaciones clínicas de estas tecnologías aún no se comprenden completamente. OBJETIVO: Evaluar los patrones y la utilidad clínica de la secuenciación genética en pacientes con cáncer rectal. DISEÑO: Análisis retrospectivo de cohortes a partir de un registro institucional mantenido de forma prospectiva. ENTORNO: Un único centro oncológico designado por el Instituto Nacional del Cáncer. PACIENTES: Un total de 251 pacientes diagnosticados con cáncer rectal entre enero de 2017 y abril de 2024, que se sometieron a pruebas genéticas. INTERVENCIONES: Secuenciación tumoral somática y análisis del ADN tumoral circulante. PRINCIPALES MEDIDAS DE RESULTADO: Respuesta al tratamiento neoadyuvante total, recidiva local y metástasis a distancia. RESULTADOS: El uso de pruebas genéticas aumentó considerablemente entre 2017 y 2024, pasando la secuenciación somática de nueva generación del 3 % al 33 % y el ADN tumoral circulante del 2 % a más del 45 %. La carga mutacional tumoral no se correlacionó significativamente con la respuesta a la terapia neoadyuvante total, la recurrencia o la metástasis. Los perfiles de mutación en las vías de carcinogénesis no mostraron diferencias significativas entre los pacientes con respuesta completa y los que presentaban enfermedad residual después del ajuste ( p = 0,145). Tras la terapia neoadyuvante total, la positividad del ADN tumoral circulante se correlacionó fuertemente con la enfermedad residual (sensibilidad: 76,5 %, especificidad: 82,4 %; p = 0,0016), y los ensayos de ADN tumoral circulante independientes del tumor demostraron una sensibilidad significativamente mayor que las pruebas basadas en el tumor (100 % frente a 50 %, p = 0,03). LIMITACIONES: Diseño retrospectivo, posible sesgo de selección, datos de un solo centro. CONCLUSIONES: A pesar de su creciente adopción, la secuenciación somática de nueva generación por sí sola carece de una utilidad pronóstica o predictiva clara para el tratamiento del cáncer rectal. Por el contrario, las pruebas de ADN tumoral circulante demostraron un gran potencial para evaluar la respuesta a la terapia neoadyuvante total, especialmente cuando se utilizan plataformas independientes del tumor. Se necesitan más estudios prospectivos para perfeccionar las directrices clínicas e integrar plenamente estas tecnologías genéticas en la atención del cáncer rectal. ( AI-generated translation )

Pancreatic adenocarcinoma is a devastating disease with an abysmal survival rate of 9%. A robust fibro-inflammatory and desmoplastic stroma, characteristic of pancreatic cancer, contributes to the challenges in developing viable therapeutic strategies in this disease. Apart from constricting blood vessels and preventing efficient drug delivery to the tumor, the stroma also contributes to aggressive biology of the cancer along with its immune-evasive microenvironment. In this study, we show that in pancreatic tumors, the developing stroma increases tumor initiation frequency in pancreatic cancer cells in vivo by enriching for CD133+ aggressive “stem-like” cells. Additionally, the stromal fibroblasts secrete IL6 as the major cytokine, increases glycolytic flux in the pancreatic tumor cells and increases lactate efflux in the microenvironment via activation of the STAT signaling pathway. We also show that the secreted lactate favors activation of M2 macrophages in the tumor microenvironment, which excludes CD8+ T-cells in the tumor. Our data additionally confirms that treatment of pancreatic tumors with anti-IL6 antibody results in tumor regression as well as decreased CD133+ population within the tumor. Furthermore, inhibiting the lactate efflux in the microenvironment reduces M2 macrophages, and makes pancreatic tumors more responsive to anti-PD1 therapy. This suggests that stromal IL6 driven metabolic reprogramming plays a significant role in the development of an immune evasive microenvironment. In conclusion, our study shows that targeting the metabolic pathways affected by stromal IL6 can make pancreatic tumors amenable to checkpoint inhibitor therapy.