Pancreatic ductal adenocarcinoma (PDAC) remains highly refractory to treatment. While the KRAS oncogene is present in almost all PDAC cases and accounts for many of the malignant feats of PDAC, targeting KRAS or its canonical, direct effector cascades remains unsuccessful in patients. The recalcitrant nature of PDAC is also heavily influenced by its highly fibro-inflammatory tumor microenvironment (TME), which comprises an acellular extracellular matrix and various types of non-neoplastic cells including fibroblasts, immune cells, and adipocytes, underscoring the critical need to delineate the bidirectional signaling interplay between PDAC cells and the TME in order to develop novel therapeutic strategies. The impact of tumor-cell KRAS signaling on various cell types in the TME has been well covered by several reviews. In this article, we critically reviewed evidence, including work from our group, on how the feedback inflammatory signals from the TME impact and synergize with oncogenic KRAS signaling in PDAC cells, ultimately augmenting their malignant behavior. We discussed past and ongoing clinical trials that target key inflammatory pathways in PDAC and highlight lessons to be learned from outcomes. Lastly, we provided our perspective on the future of developing therapeutic strategies for PDAC through understanding the breadth and complexity of KRAS and the inflammatory signaling network.

Purpose: Vitamin D analogues remodel the desmoplastic stroma, and improve vascularity and efficacy of chemotherapy in preclinical pancreas cancer models. Patients and Methods: We conducted a pilot study to evaluate the safety and preliminary efficacy of the vitamin D analogue paricalcitol in combination with nanoliposomal irinotecan (Nal-iri) plus 5-fluorouracil/leucovorin (5-FU/LV) in patients with advanced pancreatic cancer who had progressed on gemcitabine-based therapy. Two dose levels (DL) of paricalcitol were tested: fixed dose weekly (75 mcg, DL1) and weight-based weekly (7 mcg/kg, /DL2). The primary endpoint was safety, and secondary endpoints included overall response rate, progression-free survival (PFS), and overall survival (OS). Correlative objectives aimed to identify molecular predictors of response and alterations in the tumor stroma. Results: Twenty patients (10 each in DL1 and DL2) enrolled between March 2019 and May 2021. No grade 3/4 adverse events related to paricalcitol were observed. The most common toxicities were nausea, diarrhea and fatigue, which were similar in both cohorts. Three patients discontinued study after one cycle and were not radiographically evaluable. Of the remaining 17 evaluable patients, 2 had partial response and 12 had stable disease. The median PFS for response-evaluable patients in DL1 was 4.14 months, for DL2 was 4.83 months. Intent-to-treat median OS was 6.15 and 6.66 months for DL1 and DL2, respectively. Correlative studies showed increased tumor vascularity in posttreatment samples in patients receiving the higher dose of paricalcitol (DL2). Conclusions: Paricalcitol at 7 mcg/kg/week in combination with Nal-iri/ 5-FU/LV is safely tolerated, may increase tumor vascularity and warrants further investigation.

Acquired resistance limits the therapeutic efficacy of KRAS-MAPK inhibitors in pancreatic ductal adenocarcinoma (PDAC). As transcriptional plasticity and epithelial-to-mesenchymal transition (EMT) have been implicated in resistance, we sought to study the molecular mechanisms driving these changes to uncover actionable vulnerabilities. Sustained KRAS-MAPK inhibition induced interferon (IFN) and NF-κB signaling and promoted cell state change mimicking an EMT state associated with drug resistance. Network analysis identified the IFN-inducible E3 ubiquitin ligase TRIM22 as a central regulator of this response. Mechanistically, TRIM22 promoted proteasomal degradation of IκBα, resulting in sustained NF-κB and EMT program activation that coincided with a basal-like transcriptional cell state. TRIM22 expression was driven by IRF1 and IRF9 following relief of ERK-mediated transcriptional repression during pathway inhibition. EMT induction was accompanied by marked upregulation of TROP2 (TACSTD2), an NF-κB target gene enriched in basal-like PDAC cell states. Combining TROP2-directed antibody–drug conjugate sacituzumab govitecan with KRAS or ERK inhibitors significantly suppressed PDAC tumor growth in xenograft models. Overall, prolonged KRAS-MAPK inhibition activates an IFN–TRIM22–NF-κB axis that drives EMT and therapeutic resistance in PDAC, while revealing TROP2 as a clinically actionable vulnerability to overcome acquired resistance. Significance: TRIM22 drives interferon-induced EMT and NF-κB–dependent TROP2 upregulation to drive resistance to KRAS-MAPK inhibition in pancreatic cancer, which can be overcome by combining sacituzumab govitecan with KRAS-MAPK inhibitors.

Purpose:Vitamin D analogues remodel the desmoplastic stroma, and improve vascularity and efficacy of chemotherapy in preclinical pancreas cancer models.Patients and Methods:We conducted a pilot study to evaluate the safety and preliminary efficacy of the vitamin D analogue paricalcitol in combination with nanoliposomal irinotecan (Nal-iri) plus 5-fluorouracil/leucovorin (5-FU/LV) in patients with advanced pancreatic cancer who had progressed on gemcitabine-based therapy. Two dose levels (DL) of paricalcitol were tested: fixed dose weekly (75 mcg, DL1) and weight-based weekly (7 mcg/kg, /DL2). The primary endpoint was safety, and secondary endpoints included overall response rate, progression-free survival (PFS), and overall survival (OS). Correlative objectives aimed to identify molecular predictors of response and alterations in the tumor stroma.Results:Twenty patients (10 each in DL1 and DL2) enrolled between March 2019 and May 2021. No grade 3/4 adverse events related to paricalcitol were observed. The most common toxicities were nausea, diarrhea and fatigue, which were similar in both cohorts. Three patients discontinued study after one cycle and were not radiographically evaluable. Of the remaining 17 evaluable patients, 2 had partial response and 12 had stable disease. The median PFS for response-evaluable patients in DL1 was 4.14 months, for DL2 was 4.83 months. Intent-to-treat median OS was 6.15 and 6.66 months for DL1 and DL2, respectively. Correlative studies showed increased tumor vascularity in posttreatment samples in patients receiving the higher dose of paricalcitol (DL2).Conclusions:Paricalcitol at 7 mcg/kg/week in combination with Nal-iri/ 5-FU/LV is safely tolerated, may increase tumor vascularity and warrants further investigation.

Background and Aims: Targeting the Transforming Growth Factor-β (TGF-β) pathway to reverse the immunologically “cold” tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) remains clinically unsuccessful, warranting novel therapeutic strategies. Methods: We developed a novel tumor-CD8 T cell co-culture to interrogate the TGF-β signaling pathways that promotes T cell-mediated cytotoxicity. We performed multiplex immunohistochemistry (mIHC) on human PDAC samples to correlate cell-type specific TGF-β pathway activation and CD8 T cell abundance. We employed specific pathway inhibitor and newly generated genetically-engineered mouse models (GEMMs) and confirmed our findings using single-cell RNA sequencing, flow cytometry and mIHC. We performed proteomics and various in vitro assays to establish the molecular mechanisms. Results: We identify TGF-β-activated kinase 1 (TAK1 or MAP3K7) as an aberrantly activated kinase in human and mouse PDAC tissues that is associated with T cell dysfunction. Pharmacological inhibition of TAK1 with Takinib, or genetic deletion of MAP3K7 in autochthonous p48-Cre;TP53 ^flox/flox ;LSL-KRAS ^G12D GEMM, enhances intratumoral CD4 ⁺ and CD8 ⁺ effector T cell infiltration and renders immune checkpoint blockade (ICB) effective. Mechanistically, TAK1 inhibition induces DNA damage and cytoplasmic DNA leakage, which activates the cyclic GMP-AMP synthase–Stimulator of Interferon Genes (cGAS–STING) DNA sensing pathway, triggering inflammatory responses that promote adaptive immune cell infiltration. At the molecular level, TAK1 phosphorylates Ephrin Receptor A2 (EphA2) at Serine 897, which in turn phosphorylates RAD51 at Tyrosine 315, a key DNA repair protein involved in homologous recombination. Conclusions: We uncover TAK1 as a critical mediator in maintaining genomic integrity and highlights its potential as a therapeutic target to induce an inflamed TME that sensitizes PDAC to ICB.

Purpose:Vitamin D analogues remodel the desmoplastic stroma, and improve vascularity and efficacy of chemotherapy in preclinical pancreas cancer models.Patients and Methods:We conducted a pilot study to evaluate the safety and preliminary efficacy of the vitamin D analogue paricalcitol in combination with nanoliposomal irinotecan (Nal-iri) plus 5-fluorouracil/leucovorin (5-FU/LV) in patients with advanced pancreatic cancer who had progressed on gemcitabine-based therapy. Two dose levels (DL) of paricalcitol were tested: fixed dose weekly (75 mcg, DL1) and weight-based weekly (7 mcg/kg, /DL2). The primary endpoint was safety, and secondary endpoints included overall response rate, progression-free survival (PFS), and overall survival (OS). Correlative objectives aimed to identify molecular predictors of response and alterations in the tumor stroma.Results:Twenty patients (10 each in DL1 and DL2) enrolled between March 2019 and May 2021. No grade 3/4 adverse events related to paricalcitol were observed. The most common toxicities were nausea, diarrhea and fatigue, which were similar in both cohorts. Three patients discontinued study after one cycle and were not radiographically evaluable. Of the remaining 17 evaluable patients, 2 had partial response and 12 had stable disease. The median PFS for response-evaluable patients in DL1 was 4.14 months, for DL2 was 4.83 months. Intent-to-treat median OS was 6.15 and 6.66 months for DL1 and DL2, respectively. Correlative studies showed increased tumor vascularity in posttreatment samples in patients receiving the higher dose of paricalcitol (DL2).Conclusions:Paricalcitol at 7 mcg/kg/week in combination with Nal-iri/ 5-FU/LV is safely tolerated, may increase tumor vascularity and warrants further investigation.