The anionic derivative of asymmetric triblock copolymer containing biocompatible chemically complementary polyacrylamide and poly(ethylene oxide) (PAAm-b-PEO-b-PAAm) was obtained. The micellization of the initial (TBC) and modified (TBC-COOH) copolymer samples in aqueous solution were investigated. The similar values of the critical micellization concentration and the Gibbs free micellization energy for initial and modified TBCs were found. The anticancer effects of the doxorubicin (DOX)-loaded micelles of the initial and modified triblock copolymers were studied. The fact of higher efficacy of DOX/TBC and DOX/TBC-COOH compositions in compare with pure DOX was determined and discussed.