Synthesis of Cetuximab-Immunoliposomes via a Cholesterol-Based Membrane Anchor for Targeted Delivery of a Neutron Capture Therapy (NCT) Agent to Glioma Cells

摘要

The objective of the present study was to construct epidermal growth factor receptor (EGFR) targeting cetuximab immunoliposomes (ILs) for targeted delivery of boron compounds to EGFR(+) glioma cells for neutron capture therapy. The ILs were synthesized by using a novel cholesterol-based membrane anchor, maleimido-PEG-cholesterol (Mal-PEG-Chol), to incorporate cetuximab into liposomes by either surface conjugation or a post-insertion method. For post-insertion, transfer efficiency of MAb conjugates from micelles to liposome was examined at varying temperatures, mPEG2000-DSPE ratios, and micelle-to-liposome lipid ratios. Following this, the cetuximab-ILs were evaluated for targeted delivery of the encapsulated boron anion, dodecahydro-closo-dodecaborate (2−) (B12H12²⁻), to human EGFR gene transfected F98EGFR glioma cells as potential delivery agents for boron neutron capture therapy (BNCT). In addition, cellular uptake of cetuximab-ILs, encapsulating a fluorescence dye, was analyzed by confocal fluorescence microscopy and flow cytometry, and boron content was quantified by ICP-MS. Much greater (~ 8-fold) cellular uptake of boron was obtained using cetuximab-ILs in EGFR(+) F98EGFR compared with non-targeted human IgG-ILs. Based on these observations, we have concluded that cholesterol can serve as an effective anchor for MAb in liposomes and cetuximab-ILs are potentially useful delivery vehicles for BNCT of gliomas.