Liposome composite body

A method for treating a tumor comprising:

• administering to a subject in need thereof an effective amount of a liposome comprising an anti-cancer agent and a liposome membrane-constituting substance, wherein the liposome membrane-constituting substance is (a) anchored in the hydrophobic membrane region of a liposome and (b) covalently bonded to a light-absorbing compound having an absorption wavelength in the near-infrared region, the light-absorbing compound comprising an indocyanine green dye, the anti-cancer agent being contained in the liposome;
• and
• irradiating an affected area of the subject with light;
• wherein the liposome membrane-constituting substance covalently bonded to the light-absorbing compound is represented by formula (I) below:
• A-(CH2)a-B1-(CH2)b-B2-D-E1 (I)
• wherein A represents the light-absorbing compound;
• B1 and B2 each independently represent —CH2—, —CH═CH—, —O—, —S—, —NH—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —PO4H—, or —PO4M- (where M represents an alkali metal ion);
• D represents —CHE2-, —CH2CH(OCOE2)-CH2OCO—, or —CHE2-CH2OCO—;
• E1 represents a substituted or unsubstituted hydrocarbon group having 8 to 18 carbon atoms;
• E2 represents hydrogen or a substituted or unsubstituted hydrocarbon group having 8 to 18 carbon atoms;
• and
• a represents an integer of 0 to 4 and b represents an integer of 0 to 6.