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Leuk Res. 2009 Jan;33(1):129-39. doi: 10.1016/j.leukres.2008.06.028. Epub 2008 Aug 3.

In vivo maintenance of synergistic cytarabine:daunorubicin ratios greatly enhances therapeutic efficacy.

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  • 1Celator Pharmaceuticals Corporation, 1779 West 75th Avenue, Vancouver, BC, Canada V6P 6P2. ptardi@celatorpharma.com


We demonstrate here that cytarabine and daunorubicin, a standard drug combination used in the treatment of leukaemia, exhibits drug ratio-dependent synergistic antitumor activity in vitro and in vivo. A cytarabine:daunorubicin molar ratio of 5:1 displayed the greatest degree of synergy and minimum antagonism in a panel of 15 tumor cell lines in vitro. Co-encapsulating cytarabine and daunorubicin inside liposomes maintained the synergistic drug ratio in plasma for 24h post-injection. Liposome-encapsulated cytarabine:daunorubicin combinations exhibited drug ratio-dependent in vivo efficacy with the 5:1 molar drug ratio (designated CPX-351) having the greatest therapeutic index, despite using sub-MTD daunorubicin doses. CPX-351 exhibited superior therapeutic activity compared to free-drug cocktails, with high proportions of long-term survivors, consistent with in vivo synergy. The therapeutic advantage of CPX-351 was associated with prolonged maintenance of synergistic drug ratios in bone marrow. These results indicate that in vitro informatics on cytarabine:daunorubicin cytotoxicity can be translated in vivo to optimize the efficacy of anticancer drug combinations by controlling the exposure of drug ratios with drug delivery vehicles.

[PubMed - indexed for MEDLINE]
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