Liposomes with enhanced circulation time and method of treatment

A liposome composition for use in localizing an anthracycline anti-tumor drug in a solid tumor via the bloodstream comprising,

• liposomes (i) composed of vesicle-forming lipids and between 1-20 mole percent of an amphipathic vesicle-forming lipid derivatized with polyethyleneglycol, and (ii) having an average size in a selected size range between about 0.07-0.12 microns, and
• the drug, at least about 80% in liposome-entrapped form, and having a concentration in the liposomes is greater than 50 μg agent/pmole liposome lipid.

A method of preparing an agent for localization in a solid tumor, when the agent is administered by IV injection, comprising entrapping the agent in liposomes which are characterized by:

• (a) a composition which includes between 1-20 mole percent of an amphipathic vesicle-forming lipid derivatized with a hydrophilic polymer, and
• (b) an average liposome size in a selected size range between about 0.07-0.12 microns.

A method of localizing a compound in a solid tumor in a subject comprising,

• preparing a composition of liposomes (i) composed of vesicle-forming lipids and between 1-20 mole percent of an amphipathic vesicle-forming lipid derivatized with a hydrophilic polymer, (ii) having an average size in a selected size range between about 0.07-0.12 microns, and (iii) containing the compound in liposome-entrapped form, and
• injecting the composition intravenously in the subject in an amount effective to localize a therapeutically effective quantity of the agent in the solid tumor.

A method of treating a breast or colin carcinoma in a subject with an anthracycline antibiotic drug, comprising comprising

• entrapping the drug in liposomes (i) composed of vesicle-forming lipids and between 1-20 mole percent of an amphipathic vesicle-forming lipid derivatized with a hydrophilic polymer, and (ii) having an average size in a selected size range between about 0.07-0.12 microns, at a concentration of entrapped agent of greater than about 50 μg agent/μ-mole liposome lipid, with at least about 80% of the agent entrapped in the liposomes, and
• injecting the composition intravenously in the subject in an amount effective to localize a therapeutically effective quantity of the agent in the carcinoma.