Article ID Journal Published Year Pages File Type
2138465 Leukemia Research 2010 10 Pages PDF
Abstract
The objective of this study was to examine the pharmacodynamic basis for the potent preclinical and clinical anti-leukemic activity of CPX-351, a nano-scale liposome formulation of cytarabine and daunorubicin co-encapsulated at a synergistic 5:1 molar ratio. A bone marrow-engrafting CCRF-CEM leukemia model in Rag2-M mice was utilized to correlate the therapeutic and myelosuppressive properties of CPX-351 with bone marrow delivery and drug uptake in leukemia cells relative to normal bone marrow cell populations. When administered to mice bearing CCRF-CEM human leukemia xenografts, CPX-351 ablated bone marrow (BM) leukemic cells to below detectable levels for multiple weeks, whereas the free-drug cocktail only transiently suppressed leukemia growth. In contrast to the activity against leukemia cells, CPX-351 and free-drug cocktail induced similar myelosuppression in non-tumor-bearing BM. In leukemia-laden BM, drug concentrations were markedly elevated for CPX-351 over free-drug cocktail and the first dose of CPX-351, but not free-drug cocktail, potentiated BM drug accumulation for subsequent doses. Confocal fluorescence microscopy revealed that CPX-351 liposomes are taken up by CCRF-CEM cells and subsequently release drugs intracellularly. The improved in vivo efficacy of CPX-351 appears related to increased and prolonged exposure of synergistic cytarabine:daunorubicin ratios in BM, and the selective killing of leukemia may arise from direct liposome-leukemia cell interactions. These features may also have broader applicability in the treatment of other haematological malignancies.
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