Experimental: Chemotherapy plus EUS-RFA

Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) and chemotherapy will be administered as part of standard of care treatment for PDAC in patients receiving palliative second- or third-line therapy for unresectable non-metastatic pancreatic cancer.~Study participants will undergo 3 identical EUS-RFA procedures, administered during Study Window 2 (Weeks 1-3), Window 3 (Weeks 5-7), and Window 4 (Weeks 9-11). During each EUS-RFA procedure, a tumor biopsy will also be taken for single cell RNA sequencing.~Chemotherapy will be administered during Study Window 2 (Weeks 1-3), Window 3 (Weeks 5-7), Window 4 (Weeks 9-11), and Window 5 (Weeks 13-15).