NAMPT inhibition enhances the efficacy of standard chemotherapies and immunomodulation in pancreatic ductal adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by high metabolic demand and dependency on NAD salvage pathways. NAMPT, the rate-limiting enzyme in NAD biosynthesis, is upregulated in PDAC and supports tumor survival under therapeutic stress. We investigated the preclinical activity of a novel hyperbolic NAMPT inhibitor (NAMPTi) in combination with standard-of-care (SOC) chemotherapy regimens including gemcitabine, paclitaxel, 5-FU, oxaliplatin, hydroxychloroquine, and paricalcitol to determine whether NAMPT blockade enhances cytotoxic and immunomodulatory responses. Methods: Human and murine PDAC cell lines (PANC-1, MIA PaCa-2, KPC-Luc, and patient-derived 2838c) were treated with NAMPTi (5 μM) alone or with SOC agents at clinically relevant doses. Synergy was assessed in 2D viability and 3D spheroid assays. Olaparib combinations were also tested in BRCA-related models. In vivo, KPC allografts received NAMPTi (20 mg/kg, 5×/week) with gemcitabine, paclitaxel, hydroxychloroquine, 5-FU, oxaliplatin, or paricalcitol for three weeks. Immune infiltrates (CD45+, CD8+, CD4+ subsets), functional markers (GZMB, CD107a, IFNgamma, TNFalpha), and fibroblast subtypes (apCAF, myCAF, iCAF) were quantified by flow cytometry. Results: Across all PDAC models, NAMPTi alone produced modest growth inhibition, while combination treatment consistently outperformed monotherapies. NAMPTi synergized with gemcitabine-paclitaxel-hydroxychloroquine and gemcitabine-paclitaxel regimens, significantly reducing cell viability in both human and KPC-derived lines. In vivo, NAMPTi combinations markedly suppressed KPC tumor growth compared to SOC alone and reduced metastatic burden to liver and lung (e.g., GPH+NAMPTi: 60% metastasis-negative vs. 20-40% in monotherapy groups). Dual treatment increased CD8+ T-cell infiltration and effector phenotypes, enhanced cytotoxic function (GZMB+, CD107a+), and elevated IFNgamma and TNFalpha production. NAMPTi also shifted fibroblast composition, with significant reductions in myCAFs and apCAFs, suggesting stromal remodeling. In FO and GPH regimens, combining NAMPTi produced superior tumor control, decreased immunosuppressive cell populations, and improved effector memory T-cell signatures. Conclusions: NAMPT inhibition robustly enhances SOC chemotherapy efficacy in PDAC by simultaneously amplifying cytotoxic responses, remodeling the tumor immune microenvironment, and reducing metastatic spread. These findings support NAMPTi-based combinations as a promising therapeutic strategy and justify further translational development, including biomarker-driven clinical evaluation in PDAC. "Generative AI was used for improving the language of the abstract".