Peptide-functionalized magnetic nanobeads for EpCAM-targeted CTC isolation and immunotherapy efficacy evaluation in liver cancer.

Primary liver cancer lacks robust biomarkers for anti-PD-1/PD-L1 therapy. Methods: We engineered peptide-functionalized magnetic nanobeads (Pep@MNPs) for high-efficiency, EpCAM-dependent capture of circulating tumor cells (CTCs). This nanotechnology-based platform enabled a precise fluorescence quantitative system (cTPS) associate with immunotherapy outcomes in hepatocellular carcinoma and intrahepatic cholangiocarcinoma. The Pep@MNPs system revealed a significant correlation between high CTC PD-L1 expression and therapeutic response. Patients with baseline cTPShigh (≥20%) achieved a superior objective response rate compared to the low-expression group (40% vs. 0%; P = 0.005). Utilizing this nanobead-enabled quantification, cTPShigh patients demonstrated significantly prolonged progression-free survival (median 48.29 vs. 5.86 weeks, P = 0.005) and overall survival (median undefined vs. 25.71 weeks, P = 0.004). Furthermore, multivariate Cox regression confirmed cTPShigh as a robust independent predictor for both PFS and OS (both P = 0.005) after adjusting for clinical variables. This peptide-nanobead liquid biopsy strategy effectively stratifies patients benefiting from PD-1 inhibitors, highlighting its potential as a precise theranostic tool for clinical monitoring.