ADA2-Functionalized OMVs Remodel the Tumor Microenvironment in Pancreatic Cancer.

Background/Objectives: Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with a desmoplastic, immunosuppressive tumor microenvironment enriched in extracellular adenosine. High adenosine levels disrupt anti-tumor immunity by engaging adenosine receptors on T cells, macrophages, and dendritic cells. In this context, strategies to reduce extracellular adenosine signaling within the TME are in focus. Among them, enzymatic degradation of extracellular adenosine levels has emerged as a promising approach to overcome immune suppression and restore anti-tumor immune responses. Methods: Here, we engineered an E. coli strain to express a surface-bound form of a bacterial ADA2 enzyme and used the outer membrane vesicles produced by this strain as nanoparticles carrying the functional enzyme. Our data indicate robust surface expression and enzymatic activity of ADA2 on OMV particles. Results: In a PDAC subcutaneous flank tumor model, intratumoral administration of OMV-ADA2 particles was associated with significantly increased infiltration of CD8+ T cells and Granzyme B expression and concomitant decreases in collagen deposition and α-smooth muscle actin (α-SMA) positive stromal cells, suggesting modulation of the desmoplastic stroma. Conclusions: These findings support further investigation of OMV-bADA2 as a potential platform to modulate tumor metabolism and stroma, activate anti-tumor immunity, and serve as a carrier for co-delivery of additional anticancer modalities in PDAC.