Sequential cryoablation enhances chemotherapeutic efficacy in pancreatic cancer by downregulating TGF-β mediated fibrosis in the sub-lethal zone.

Cryoablation is effective for solid tumors but is often constrained by limited thermal efficiency and incomplete ablation. Conventional strategies prioritize expanding lethal isotherms to minimize the sub-lethal zone, a practice that increases the risk of collateral injury to adjacent critical structures. This study proposes a novel strategy utilizing the sub-lethal zone to remodel the tumor microenvironment for enhanced therapeutic efficacy. Using pancreatic cancer and stellate cell co-cultured spheroids and subcutaneous tumor models, we investigated fibrotic tumor microenvironment changes induced by the cryoablation sub-lethal zone combined with gemcitabine plus nab-paclitaxel. Results demonstrated that cryoablation significantly disrupted collagen structures and downregulated TGF-β1, p-Smad3, α-SMA, and Collagen I expression. This modulation is associated with the mitigation of fibrotic barriers, thereby potentially improving the accessibility of chemotherapy drugs within the sub-lethal zone. In vivo, cryoablation followed by chemotherapy yielded optimal efficacy compared to reverse sequencing or monotherapy, significantly inhibiting angiogenesis and promoting mitochondrial apoptosis via upregulated Bax and Caspase-3 levels. In conclusion, cryoablation functions as a potent tumor microenvironment remodeler. By downregulating TGF-β/Smad signaling, it sensitizes pancreatic ductal adenocarcinoma to subsequent chemotherapy, offering a superior sequential strategy to effectively inhibit the growth of residual tumor cells, offering an approach to improve local tumor control in PDAC.