MRTX1133 sensitivty across the PRISM cohort of cell lines.

Oncogenic RAS drives an immunosuppressive tumor microenvironment in pancreatic ductal adenocarcinoma (PDAC). Inhibition of RAS signaling, as is now possible with an ever-increasing pharmaceutical portfolio, not only directly blocks tumor cells but also reverses immunosuppression, enabling infiltration of cytotoxic T cells and major alteration of the tumor microenvironment. In preclinical studies, the full antitumor effects of RAS inhibitors depend on T cells such that regressions in mice lacking T cells (or cross-presenting dendritic cells) are less deep and less durable than those in T cell-replete mice. Moreover, RAS inhibitors given with immune checkpoint blockade and immune agonists produce even more potent antitumor effects, especially in tumors with some amount of baseline T-cell infiltration. These findings set the stage for testing RAS inhibitors and immunotherapy in combination for PDAC, which is otherwise refractory to immunotherapy. Other immune partners might include vaccines, bispecific antibodies, and cell therapy. A major clinical opportunity eventually would be combining RAS inhibitors and immunotherapy in the adjuvant, neoadjuvant, and interception settings, provided this new class of drugs is developed keeping its immune-modulatory power in mind.

Abstract Cancer interception is a clinical approach to eliminate pre-malignant lesions, distinct from approaches to treat invasive cancer, but effective strategies in pancreatic ductal adenocarcinoma (PDAC) remain to be identified. Conceptually, interception strategies should target precancerous lesions such as pancreatic intraepithelial neoplasia (PanINs) to prevent malignant transformation. Because PanINs overwhelmingly harbor oncogenic KRAS mutations as an inceptive genetic event, we utilized a mouse model of PDAC to evaluate the potential of RAS inhibition to intercept pancreas premalignancy. Short-term treatment (10 days) of PanIN-bearing, tumor-free KrasG12D Trp53R172H/+ Pdx1-Cre (KPC) mice with the RAS(ON) multi-selective inhibitor RMC-7977 reduced the prevalence of premalignant lesions, as assessed by H&E staining and confirmed by 3-dimensional, cellular-resolution reconstruction of pancreata (CODA). Residual premalignant cells exhibited elevated cell death in the presence of RMC-7977 compared to control. Extended treatment with RMC-7977 (28 days) led to more profound elimination of PanIN lesions. This decreased neoplastic burden delayed tumor onset by a mean of 36.5 +/- 6 days and increased overall survival (OS) by 1.2-fold. Long-term interception with metronomic administration (1 week on/1 week off) of RMC-7977 in KPC mice resulted in near tripling of median tumor-free survival and OS, extending median survival to 376 +/- 106 days compared to 138 +/- 38 days in non-intercepted controls. Evaluation of escape tumors arising under long-term interception revealed aggressive tumors typical of the KPC model that retained some sensitivity to continued RAS inhibition. Notably, long-term cancer interception with RMC-7977 conferred a survival benefit of 25 weeks (p<0.0001) compared to the use of RMC-7977 at the time of cancer diagnosis in KPC mice. We conclude that targeted pharmacological cancer interception reduces premalignant PanIN lesions and substantially extends survival in preclinical models of PDAC, supporting clinical evaluation of RAS inhibitors for pancreatic cancer interception. Citation Format: Minh T. Than, Lucie Dequiedt, Rina Sor, Shreya Nair, Nune Markosyan, Emma E. Furth, Chenghua Yang, Courtney Ray-Fofana, Marie Menard, Elsa Quintana, A Cole Edwards, Connor J. Hennessey, Austin L. Good, Liz Quinones, Yunseo Hwang, Cynthia Clendenin, Ashley L. Kiemen, Robert H. Vonderheide, Ben Z. Stanger. Active RAS inhibition intercepts pancreas cancer in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr LB406.

Mono-ADP-ribosylation (MARylation) is emerging as an important regulator of anti-cancer immunity and immunosuppressive tumor microenvironment (TME). Our previous studies showed that PARP11, one of several enzymes that facilitate MARylation, regulates the activities of intratumoral cytotoxic T lymphocytes (CTLs) and regulatory T cells (Tregs). Here, we demonstrate that stimuli such as adenosine, epinephrine, or glucagon-like peptide-1 (GLP1) induced PARP11 in cancer cells. Upregulation of PARP11 in cancer cells led to PARP11-mediated MARylation, ubiquitination, and accelerated degradation of MHC-I through the autophagy-lysosomal pathway. Induction of PARP11 protected cancer cells from killing by specific CTLs and stimulated tumor growth and progression. Genetic ablation of PARP11 attenuated MHC-I MARylation, ubiquitination, and interaction with autophagy receptors. Pharmacologic inhibition of PARP11 in pancreatic ductal adenocarcinoma (PDAC) cells restored their MHC-I levels, sensitized them to killing by CTLs, inhibited tumor growth, and impeded their initial resistance to chemotherapy and their acquired resistance to targeted therapy with RAS inhibitors. Moreover, inhibition of PARP11 prevented hyperprogressive disease in a mouse melanoma model treated with immune checkpoint inhibitors (ICBs), suggesting that PARP11 is a major therapeutically actionable driver of immunosuppression in tumors. SYNOPSIS:Induction of PARP11 in the tumor microenvironment mediates immunosuppression. This study reports that PARP11-driven MARylation and ubiquitination of MHC-I in cancer cells drives immune evasion, tumor growth and resistance to therapies.

Immunosuppressive tumor microenvironment (TME) inactivates CD8+ cytotoxic lymphocytes (CTLs). Here, we identify SPTBN2 spectrin as a key immunosuppressive regulator induced in CTLs in response to nutritional deficit. In human pancreatic and colorectal cancers, SPTBN2 expression negatively correlated with CTL infiltration and patients' survival. In TME of mouse pancreatic and colorectal adenocarcinomas, SPTBN2 inactivated intratumoral CTLs, stimulated tumor growth and conferred cross-resistance to anti-cancer therapies. SPTBN2 knockout protected CAR T-cells from trogocytosis and increased their memory state. SPTBN2 maintained levels of cell surface proteins such as BTLA that undermine CAR T-cell cytotoxicity and promote exhaustion. Re-expression of BTLA largely reversed phenotypes in SPTBN2-deficient CAR T-cells. In manufactured CAR T cells, SPTBN2 was associated with their clinical failure in pediatric patients with leukemia. Accordingly, ablation of SPTBN2 in CAR T-cells increased their cytotoxicity, in vivo persistence and therapeutic effects indicating that SPTBN2 can be targeted to increase the efficacy of anti-cancer therapies.

Ferroptos is is an iron-dependent form of cell death converging on lipid peroxidation first identified by examining compounds with enhanced lethality to KRAS mutant cells. Despite over 90% of pancreatic ductal adenocarcinoma (PDAC) tumors harboring KRAS mutations, PDAC exhibits relative resistance to ferroptosis compared with other tumor types, and the mechanisms behind this resistance remain unclear. Here, we report that exposure to pancreatic tumor interstitial fluid in synergy with hypoxia induced robust protection against ferroptosis in a manner dependent on the hypoxia-inducible transcription factor 2 (HIF-2). HIF-2 upregulates the expression of both components of the system Xc-cystine transporter and transsulfuration pathway enzymes CBS and CTH to increase intracellular cysteine levels, enabling anti-ferroptotic glutathione production. HIF-2 also induces the Parkin mitophagy factor and suppresses mitochondrial function and reactive oxygen species (ROS) generation. Altogether, our findings uncover an unforeseen role of the HIF-2 transcription factor as a coordinator of anti-ferroptotic mechanisms in pancreatic cancer.

Genetic and copy number variants at resistance to adagrasib or sotorasib across the novel cohort of PDAC and GI cancer patients.

Supplemental Table 5A: Drug sensitivity metrics from MRTX1133-treated KRASG12D patient-derived organoids. Supplemental Table 5B: MRTX1133 dose response across KRASG12D mutated patient-derived organoids.

Supplemental Table 4A: Differential gene expression analysis between MRTX1133 sensitive and resistant KRASG12D cell lines. Supplemental Table 4B: Analysis of Copy number and RPPA datasets between MRTX1133 sensitive and resistant KRASG12D cell lines.

Supplemental Figure 1: Acquired resistance to KRASG12C inhibition in PDAC and other GI cancers. Supplemental Figure 2: MRTX1133 sensitivity across KRASG12D mutant in vitro models of PDAC. Supplemental Figure 3: Isogenic models of acquired resistance to MRTX1133. Supplemental Figure 4: In vivo treatment and tumor monitoring for the KPC PDAC mouse model. Supplemental Figure 5: Genomic characterization of KPC tumors. Supplemental Figure 6: snRNA-seq quality metrics and description of the tumor microenvironment. Supplemental Figure 7: Identification and characterization of malignant cell populations. Supplemental Figure 8: Characterization of malignant metaprograms in KPC tumors. Supplemental Figure 9: Treatment with MRTX1133 induces modest changes in the immune microenvironment following tumor regression. Supplemental Figure 10: Treatment of 6694C2-LM tumors with MRTX1133 reduces granulocytes but has little effect on T cells. Supplemental Figure 11: Neoadjuvant and adjuvant therapy in a metastatic model of PDAC.

The Tn antigen, a truncated O-glycan, is frequently elevated in pancreatic ductal adenocarcinoma (PDAC). Multiple therapeutic approaches targeting Tn have been developed, but they have not demonstrated clear efficacy signals in early phase clinical studies. Improving Tn-targeted strategies in PDAC will require both overcoming the immunosuppressive tumor microenvironment and defining pathways by which truncated O-glycans promote growth and immune evasion. Here, we showed that Tn reshapes the tumor immune landscape of PDAC. Expression of Tn antigen on PDAC cells enhanced proliferation in vitro and tumor growth in vivo. Tn expression remodeled the immune microenvironment, skewing tumor-associated macrophages toward M2-like phenotypes, reducing cross-presenting dendritic cells, and expanding myeloid-derived suppressor cells (MDSCs). Single-cell RNA sequencing confirmed expansion of MDSCs and downregulation of antigen processing and presentation in the immune cell infiltrate of Tn+ tumors. Tumor-intrinsic transcriptomic analyses revealed activation of TNF-α/NF-κB signaling and induction of IL-34, a cytokine linked to monocyte survival and differentiation in Tn antigen expressing tumors. Additionally, high Tn expression in both organoids derived from pancreatic cancer patients and in PDAC mouse models was associated with increased IL-34 expression. Genetic deletion of Il34 in PDAC cells attenuated Tn-driven tumorigenesis and reduced MDSC infiltration, while recombinant IL-34 promoted myeloid cell differentiation and proliferation in vitro. Together, these findings establish a glyco-immune-cytokine axis in which truncated O-glycans contribute to IL-34-mediated immunosuppression, providing mechanistic insight and potential therapeutic targets in PDAC.

Abstract Direct RAS inhibitors are poised to transform the treatment landscape for pancreatic ductal adenocarcinoma (PDAC), where frontline therapy remains cytotoxic chemotherapy with limited clinical benefit. Despite this progress, intrinsic and acquired resistance limit the depth and duration of response. While putative genetic resistance mechanisms explain approximately 50% of cases in non-small cell lung cancer, colorectal cancer, and PDAC, the non-genetic mechanisms driving the remaining 50% remain poorly defined. We utilized transcriptomics, proteomics, and CRISPR-Cas9 genetic screens to elucidate the adaptive programs driving KRAS-independent growth. We identified the activation of distinct transcriptional drivers—MYC, YAP-TEAD, and KEAP1-NRF2—that bypass KRAS inhibition to sustain the resistant state. Comparative RNA-sequencing revealed that MYC- and TEAD-driven networks share substantial overlap with RAS-regulated networks, converging on essential cell cycle and growth genes. In contrast, the KEAP1-NRF2 network operates via a distinct axis characterized by increased dependence on glutamine metabolism. We confirmed the enrichment of these signatures in both preclinical models and patient samples exhibiting resistance to RAS inhibition. We then sought to identify therapeutic strategies to target these resistant states. To identify the upstream signaling governing the YAP/TEAD transcriptional shift, we performed comprehensive phosphoproteomics on PDAC cell lines treated with RAS inhibitors. We observed dynamic kinome reprogramming characterized by the activation of RHO GTPase effector kinases, specifically PAK, ROCK, and PKN. Mechanistically, we demonstrate that pharmacological inhibition of ROCK or PAK decreases nuclear YAP localization and restores sensitivity to RAS inhibition. To identify therapeutic strategies to target NRF2-driven resistance, we leveraged our transcriptomics to identify a metabolic shift with increased reliance on glutamine metabolism. Functionally targeting this metabolic vulnerability with the clinically tractable glutamine antagonists, CB-839/telaglenastat or DRP-104/sirpiglenastat, significantly impaired tumor growth in NRF2-activated models. Collectively, these findings delineate a hierarchy where kinome remodeling drives the transcriptional and metabolic plasticity required for drug tolerance, highlighting the RHO-ROCK-YAP axis and NRF2-regulated glutamine metabolism as actionable targets to extend the durability of next-generation RAS therapies. Citation Format: Clint A. Stalnecker, Wen-Hsuan Chang, Brandon L. Mouery, Ryan D. Mouery, Oluwadara Coker, A. Cole. Edwards, Runying Yang, Crystal L. Pace, Laura E. Herring, Whitney L. Stutts, Joshua H. Choe, Alec J. Vaughan, Timour Baslan, Ben Z. Stanger, Kwok-Kin Wong, Thales Y. Papagiannakopoulos, Andrew J. Aguirre, Joseph D. Mancias, Adrienne D. Cox, Channing J. Der. Dynamic kinome reprogramming and metabolic rewiring drive adaptive resistance to RAS inhibition in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RAS Oncogenesis and Therapeutics; 2026 Mar 5-8; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(5_Suppl_1):Abstract nr PR013.

Abstract Background Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic malignancy with limited treatment options. Metastatic dissemination is the principal cause of mortality in PDAC, yet the cellular mechanism by which PDAC tumor cells enter the bloodstream remains unknown. A portal of intravasation is the Tumor Microenvironment of Metastasis (TMEM) doorways. The TMEM doorway is composed of a tumor cell, a Tie2 + macrophage, and endothelial cell, in direct contact triggering a brief, localized vascular opening that permits intravasation. Methods We performed time-lapse intravital microscopy in PDAC mouse models to visualize serum extravasation and tumor cell intravasation. TMEM doorway density was quantified using immunohistochemistry of resected human PDAC specimes. TMEM doorway activity was quantified by aligned immunohistochemistry/immunofluorescence of tumor specimens. Mechanistic underpinnings of intravasation were tested using an in vitro intravasation transendothelial migration (iTEM) assay. Tie2 signaling was inhibited in vivo with the Tie2 inhibitor rebastinib (~ 0.44 mg/day in chow for 3 weeks). A macrophage-specific Tie2 conditional knockout mouse was generated to evaluate macrophage Tie2-mediated PDAC dissemination. The therapeutic impact of Tie2 blockade was evaluated in an orthotopic perioperative PDAC model incorporating distal pancreatectomy and perioperative FOLFIRINOX plus rebastinib. Statistical analyses used included Mann–Whitney and Kruskal–Wallis tests for clinicopathologic comparisons, one-way ANOVA with Tukey’s post hoc test for iTEM, Student’s t-test for two-group comparisons, and Kaplan–Meier survival analysis with log-rank testing. Results In vivo imaging revealed transient, localized vascular openings spatially linked to TMEM doorways. PDAC tumor cell intravasation was observed at TMEM doorways. TMEM doorways were detectable in human PDAC tissues; higher TMEM density was associated with aggressive pathologic factors and was reduced after neoadjuvant therapy. Tie2 inhibition selectively impaired macrophage-driven vascular opening and reduced TMEM doorway activity, diminished tumor cell transendothelial migration, and lowered disseminated tumor cell burden in vivo. In therapeutic studies, Tie2 inhibition combined with FOLFIRINOX improved survival compared with FOLFIRINOX alone. Conclusions Intravasation and dissemination is TMEM doorway mediated in PDAC. TMEM doorway function is mediated by Tie2 signaling. Inhibition of Tie2 pharmacologically and genetically decreases TMEM doorway function and PDAC dissemination. Tie2 inhibition may have therapeutic potential combined with chemotherapy or emerging therapies for PDAC.

List of genes in each NMF metaprograms

Characterization of acquired resistance to KRASG12C inhibition across studies and cancer types.

Pancreatic ductal adenocarcinoma (PDAC) is a challenging malignancy to treat, but emerging evidence suggests that specific subtypes may respond more favorably to certain therapies. BRCA-mutated PDAC represents a distinct subtype that is particularly sensitive to DNA-damaging therapies. The current standard of care for advanced BRCA-mutated PDAC involves induction platinum-based chemotherapy followed by maintenance therapy with a poly (ADP-ribose) polymerase inhibitor (PARPi). However, the randomized phase III POLO trial, upon which this standard is based, did not demonstrate an improved overall survival in patients who received olaparib compared to those who received placebo, highlighting the need for new therapeutic approaches. Additionally, there is a lack of robust models that recapitulate the tumor microenvironment of BRCA mutated PDAC, limiting the development of next-generation maintenance treatment options. In this study, we developed a syngeneic and immunocompetent mouse model of Brca2-mutated PDAC. The model demonstrated high sensitivity to cisplatin plus gemcitabine, but limited efficacy of PARPi monotherapy. Induction with platinum-based chemotherapy sensitized tumors to PARPi maintenance therapy and promoted an exhausted, T cell-inflamed tumor microenvironment. However, resistance emerged which was associated with CDX2 expression and tumor differentiation. The addition of anti-PD1 treatment to PARPi maintenance enhanced tumor regression and prolonged overall survival. These findings provide preclinical support for ongoing clinical trials investigating immunotherapy with PARPi as a maintenance strategy in homologous recombination-deficient PDAC.

Antigen processing and presentation (APP) is essential for adaptive immunosurveillance. We uncover a mechanism whereby activated T cell-derived extracellular vesicles (ATEVs) drive a positive feedback loop that enhances antigen presentation and immune responses in normal physiology and cancer. ATEV-induced immunogenicity relies on extracellular vesicular double-stranded DNA (EVDNA), which is notably abundant and primarily composed of genomic DNA enriched in immune-related genes, including those encoding APP machinery. Mechanistically, granzyme B (Gzmb) packaged by ATEVs disrupts the nuclear envelope of recipient cells, facilitating intranuclear transfer and subsequent transient expression of EVDNA encoding APP genes. DNase treatment removes most AT-EVDNA, abrogating APP upregulation and thus T cell activation and recruitment to tumors. Notably, ATEVs hold promise as an acellular immunotherapy, restoring APP and synergizing with checkpoint blockade in immunotherapy-refractory tumors. Collectively, our findings uncover a mechanism of transient, non-viral gene delivery by ATEVs that boosts APP and anti-tumor immunity while limiting autoimmunity.