Delivery system for nucleic acids

An αvβ3 integrin receptor targeting liposome comprising

• a cationic lipid;
• a neutral lipid;
• a trivalent targeting lipid having a targeting domain and a hydrophobic domain bound to the targeting domain;
• and
• a nucleic acid complexed with the cationic lipid;
• the cationic lipid being present in an amount in the range of about 1 to about 50 mole percent, and said targeting lipid being present in an amount in the range of about 1 to about 20 mole percent, the mole percent values being based on total moles of lipid in the liposome, and the targeting domain including three non-peptidic αvβ3 integrin antagonists represented by formula (II):
• wherein in formula (II), R4 and R5 are each hydrogen, or together form a covalent bond;
• Y is —C(O)— or —CH2—;
• Z2 is —C(O)—R6;
• —C(O)OR6, or SO2R6;
• R6 is phenyl, substituted-phenyl, pyridyl, benzyl, substituted-benzyl;
• C1-C4 haloalkyl, C2-C30 alkyl, C2-C30 alkenyl, C2-C30 alkynyl, or cholesteryl;
• and Het is 2-pyridyl or 2-imidazolyl.