Nanoparticle drug delivery systems

The invention provides pharmaceutical compositions and method of using the compositions, wherein the compositions comprise liposomes or micelles that contain one or more targeting peptides and/or anticancer drugs. In various embodiments, the components of the liposomes can include a) a phospholipid and optionally a lipid that is not a phospholipid; b) a pegylated lipid; c) a peptide-ethylene glycol (EG)-lipid conjugate wherein the peptide is a targeting ligand, and d) one or more drug-conjugated lipid, encapsulated drugs, or a combination thereof. The peptide-EG-lipid conjugate can be, for example, a compound of Formula (I) or Formula (II). The ethylene glycol (EG) segments of the peptide-EG-lipid conjugate can be, for example, EG6 to about EG36; and the EG segment can be conjugated to one or more lysine moieties.