Evolving lipid-based delivery systems in the management of neoplastic disease

Drug delivery systems for the therapeutic use of cytotoxic chemotherapy are an essential aspect of successful treatment and remain under active evaluation. Such systems offer advantages such as they can change the pharmacologic and pharmacodynamic properties of an active drug in preclinical screens to meet the needs of therapy in humans. For example, unstable or insoluble agents can be formulated in a manner to allow effective exposure in the tumor. Liposomal delivery systems are the most mature with regulatory approval for several liposomal preparations. The liposome is attractive as the charge, size, composition, and the payload (drug) can be manipulated to enhance efficacy. Targeting agents such as antibodies, antibody fragments, or ligands can be incorporated into the liposomal structure to enhance specificity. The liposome can be manipulated to be thermal or pH sensitive. In addition, variations of the liposome can incorporate more than one agent and also allow for sequential exposure of the active agents to the tumor. Additional lipid formulations include micelles and nanocochleates, which are earlier in development, but many offer an alternative to liposomal technology. The size, shape, adducts, and composition of the micelles may offer more flexibility in the delivery platform. Further clinical trials are eagerly awaited.