 Cytarabine in combination with an anthracycline is a frequently used chemotherapy platform for both newly diagnosed and relapsedrefractory acute myeloid leukemia AML and other hematologic malignancies. Synergistic antitumor activity has been demonstrated between cytarabine and daunorubicin that is dependent upon the ratio of the drugs with the best therapeutic effect observed with a cytarabine to daunorubicin ratio of 5:1 in in vitro and in vivo models. CPX-351 is a liposomal preparation of cytarabine and daunorubicin that maintains this therapeutic drug ratio 24 hours post infusion. The altered biodistribution from encapsulation may result in a greater therapeutic effect in patients with relapsed hematologic malignancies and demonstrate greater tolerability than non-liposomal cytarabine and daunorubicin. 