Safety and feasibility of a layered embolization strategy with drug-eluting and uniform-caliber microspheres for advanced hepatocellular carcinoma and unresectable liver metastases: a prospective single-arm clinical trial

Background Advanced hepatocellular carcinoma (HCC) and unresectable liver metastases present significant therapeutic challenges, particularly in patients with portal vein tumor thrombus or complex vascular architecture. This study evaluates the safety and feasibility of a novel layered embolization strategy combining drug-eluting and uniform-caliber microspheres. Methods We conducted a prospective, single-arm clinical trial enrolling 33 patients with advanced HCC (BCLC stage C) or unresectable liver metastases and preserved liver function (Child-Pugh class A/B ≤7). The layered strategy involved initial embolization with 100-300 μm CalliSpheres ® drug-eluting microspheres loaded with epirubicin, followed by proximal flow blockade with 100/500/700 μm uniform-caliber blank microspheres. Primary endpoints were safety profiles and procedural feasibility; secondary endpoints included short-term imaging response and biomarker dynamics. Results The procedure was technically successful in all patients. Treatment-related adverse events occurred in 28 patients (84.8%), with 96.4% being grade 1–2 according to CTCAE v5.0 criteria. The most common complications were hepatic function abnormalities (72.7%) and post-embolization syndrome (60.6%). All adverse events resolved with standard management within a median of 7 days. Among 27 evaluable patients, the disease control rate was 92.6% (7 partial responses, 18 stable disease, 2 progression). Tumor biomarker dynamics showed correlation with imaging response. Conclusions This layered embolization strategy demonstrates an acceptable safety profile and technical feasibility in carefully selected patients with advanced liver tumors and preserved hepatic function. The findings provide a foundation for future randomized controlled trials to evaluate survival benefits and identify optimal patient subgroups.