The discovery of a small-molecule inhibitor of CBR1 and the evidence of improved cell killing by daunorubicin in conjunction with hydroxy-PP-Me of lung adenocarcinoma cells now allows for assessment of this potential improvement to current adjuvant therapy for treating breast cancer and childhood leukemias by reducing or preventing the cardiotoxicity currently associated with anthracycline therapy. Here, CBR1 is linked to breast cancer.