EPGD co-delivery of doxorubicin and gemcitabine enhances activity in EpCAM-high tumour models with lower renal injury-associated readouts in a microfluidic co-culture platform.

Cytotoxic chemotherapy remains indispensable for many epithelial malignancies, yet gemcitabine (GEM) and doxorubicin (DOX) are constrained by a narrow therapeutic index and clinically significant toxicity. Here, we developed an epithelial cell adhesion molecule (EpCAM)-targeted DNA aptamer (EP)-based construct for co-delivery of GEM and DOX and evaluated its antitumour activity together with renal injury-associated readouts in vitro. A GEM-integrating EP construct (EPG) was generated by substituting seven cytidines with GEM residues, followed by DOX loading through intercalation into GC-rich regions to form EPGD. Mass spectrometry confirmed the expected molecular species, and DOX association with EP/EPG was supported by fluorescence quenching. ELONA-based analyses further showed that EPG retained EpCAM binding with a modest increase in apparent Kd relative to EP, while competitive ELONA supported preserved, competitively inhibitable EpCAM engagement under the tested conditions. In an evaporation-driven microfluidic self-perfusion chip, EPGD induced greater tumour cytotoxicity and more pronounced γ-H2AX formation than free drugs or single-drug aptamer formulations at matched nominal drug concentrations. In patient-derived intrahepatic cholangiocarcinoma organoids, EPGD reduced viability in a concentration-dependent manner. In a dual-compartment microfluidic chip operated under shared perfusion, HK-2 proximal tubular cells cultured on a kidney-derived decellularised extracellular matrix showed higher viability together with lower kidney injury molecule-1 (KIM-1) secretion and lactate dehydrogenase (LDH) release after EPGD treatment than after free GEM and DOX. Together, these findings indicate that EPGD integrates CI-supported GEM/DOX synergism demonstrated in A549 cells with preferential activity in EpCAM-high tumour models and is associated with lower renal injury-associated readouts in this in vitro microfluidic platform.