Liposomally targeted cytotoxic drugs for the treatment of cancer

Phospholipid spherules composed of lipid bilayer membranes entrapping a central aqueous core were first described more than 30 years ago (Bangham et al 1965). The term liposome was coined in 1968 (Sessa & Weissmann 1968) and the first suggestions that these vesicles might have potential as vehicles for targeted drug delivery for a range of diseases, including cancer, appeared shortly afterwards (Gregoriades et al 1974; Gregoriades 1976a, b). However, the process of turning this expectation into a clinical reality has suffered a number of setbacks and has taken more than a quarter of a century. In the process, new types of liposomes with favourable in-vivo pharmacokinetics and biodistribution patterns have been generated (Lasic & Papahadjopoulos 1995). Many of these preparations have been subjected to extensive examination and an increasing number of agents have entered clinical trials. In this review, we will trace the development of those liposomes that are currently undergoing (or are about to undergo) clinical evaluation.