Patent ID: 8138200

Claim:
A compound having the structure of Formula III: wherein, R 11 is (C 1 -C 12 ) alkyl, branched alkyl, alkenyl or alkynyl; R 12 is (C 1 -C 16 ) alkyl, branched alkyl, alkenyl or alkynyl; X 11 is O, S, or NHC═O; X 12 is O, S, or NHC═O; X 13 is O or S; n is 1 or 2, and R 13 is a therapeutic agent selected from the group consisting of doxorubicin, idarubicin, epirubicin, daunorubicin, mitomycin, SN-38, camptothecin, topotecan, 9-nitrocamptothecin, and 9-aminocamptothecin, mitoxanthrone, methotrexate, and CPT-11.