Liposomes as “Trojan Horses” in Cancer Treatment: Design, Development, and Clinical Applications

Liposomes started to be studied for drug delivery in 1970s, taking advantage of their ability to encapsulate hydrophilic and hydrophobic drugs using biodegradable and biocompatible molecules. Nowadays, they remain one of the most promising strategies for drug delivery not only in cancer treatment but also in gene therapies and vaccines. The design and development of liposomal systems have evolved significantly over the past decades, moving from conventional formulations to advanced, stimulus-responsive, and multifunctional nanocarriers. Analogous to the myth of the Trojan Horse, liposomes must mislead the host immune system to reach the interior of cancer cells in order to deliver the therapeutic payload. There are many barriers that liposomes have to overcome to circulate through the bloodstream and specifically target cancer cells without damaging other tissues. Crucial parameters such as lipid composition, particle size, zeta potential, and PEGylation have been systematically optimized to enhance pharmacokinetics and biodistribution and to improve delivery efficiency. Furthermore, conjugation with antibodies, peptides, or small molecules has enabled active targeting, while stimuli such as pH, temperature, and enzymatic activity have been exploited for controlled drug release within the tumor microenvironment. Such innovations have laid the groundwork for translating liposomal formulations from the bench to clinical applications. In this paper, we evaluate the physicochemical features of liposomal design that underpin their suitability and efficacy for anticancer drug delivery. We aimed to focus on two main aspects: conducting an exhaustive review of the physicochemical parameters of liposomal drugs that have already been approved by regulatory agencies, while maintaining a pedagogical approach when explaining the key design parameters for the optimal design of liposomes in oncology in detail.