The development of novel polymers for biomedical applications remains a highly demanded field of polymer science. In this study, the radical polymerization of N-vinylsuccinimide (VSI) using S,S´-dibenzyl trithiocarbonate (DBTTC) as a reversible chain-transfer agent was investigated both in bulk and in 1,4-dioxane solution. The resulting polymers were characterized by SEC, 1H, 13С and HSQC NMR spectroscopy to determine their molecular weight distribution, conversion, and microstructure. The polymerization followed a controlled mechanism, as evidenced by linear molecular weight increase with conversion, suppression of the gel effect, and living chain behavior. The position of the trithiocarbonate group within the polymer chain was elucidated via nucleophilic and reduction reactions, and radical initiator substitution. The trithiocarbonate group was found to shift from a central to asymmetric position depending on synthesis conditions and chain length. PVSI-DBTTC was subsequently employed as a macro-RAFT agent for the synthesis of triblock copolymers with O-cholesteryl acrylate (ChA). These copolymers were analyzed by SEC, 1H NMR spectroscopy and DSC. Hydrolysis of the VSI units to N-vinylsuccinamic acid (VSAA) units yielded the amphiphilic triblock copolymer – PVSAA-b-PChA-b-PVSAA, which self-assembled into micelles in aqueous media. The resulting dispersions were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM), which revealed the formation of spherical nanoparticles with a hydrodynamic diameter of up to 200 nm and a polydispersity index (PDI) below 0.3 in phosphate-buffered saline solution (pH 7.4). The developed micelles successfully encapsulated irinotecan and exhibited pH-responsive release. Furthermore, the nanoparticles demonstrated low cytotoxicity in various cells and low uptake by macrophages, as well as preserved the potent anticancer activity of the loaded drug, making them as promising candidate for effective drug delivery.