Spurred by recent progress in medicinal chemistry, numerous lead compounds have sprung up in the past few years, although the majority are hindered by hydrophobicity, which greatly challenges druggability. In an effort to assess the potential of
platinum (Pt) candidates, the nanosizing approach to alter the pharmacology of hydrophobic Pt(IV)
prodrugs in discovery and development settings is described. The construction of a self-assembled nanoparticle (NP) platform, composed of amphiphilic
lipid-
polyethylene glycol (PEG) for effective delivery of Pt(IV)
prodrugs capable of resisting
thiol-mediated detoxification through a
glutathione (GSH)-exhausting effect, offers a promising route to synergistically improving safety and efficacy. After a systematic screening, the optimized NPs (referred to as P6 NPs) exhibited small particle size (99.3 nm), high Pt loading (11.24%), reliable dynamic stability (∼7 days), and rapid redox-triggered release (∼80% in 3 days). Subsequent experiments on cells support the emergence of P6 NPs as a highly effective means of transporting a lethal dose of cargo across cytomembranes through macropinocytosis. Upon reduction by cytoplasmic
reductants, particularly GSH, P6 NPs under disintegration released sufficient active Pt(II) metabolites, which covalently bound to target
DNA and induced significant apoptosis. The PEGylation endowed P6 NPs with in vivo longevity and
tumor specificity, which were essential to successfully inhibiting the growth of
cisplatin-sensitive and -resistant xenograft
tumors, while effectively alleviating toxic side-effects associated with
cisplatin. P6 NPs are, therefore, promising for overcoming the bottleneck in the development of Pt drugs for oncotherapy.