Abstract 1292: Pharmacokinetics of CPX-351: A nano-scale liposomal fixed molar ratio of cytarabine-daunorubicin (Cyt:Daun) in patients with advanced leukemia

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Background: CPX-351 is a liposomal formulation that co-encapsulates Cyt and Daun enabling delivery of both drugs at a synergistic 5:1 molar ratio. A Phase I study in advanced AML patients demonstrated substantial efficacy with complete remissions (CRs) and acceptable safety. The MTD was 101 units/m2. One unit of CPX-351 contains 1 mg Cyt and 0.44mg of Daun. Here we examine the PK of CPX-351 as a function of dose, inter-patient variability and patient characteristics in order to identify potential PD relationships. Methods: 35 male and female patients with advanced hematologic malignancies were included in the PK portion of this Phase I trial and received 24, 32, 43, 57, 76, 101, or 134 units/m2 of CPX-351 by IV infusion over 90 minutes on Days 1, 3, and 5. Validated LC/MS/MS assays were used for determination of total plasma Cyt and Daun. PK parameters [Cmax, AUC, t1/2, Vss, CL, Cmax/Dose, AUC/Dose] were determined on Days 1 and 5. Results: Mean Cyt and Daun PK parameters are presented in the [table below][1]. No significant differences were observed in t1/2, Vss, CL, Cmax/Dose, or AUC/Dose among dose groups on either study day, although some drug accumulation was observed from day 1 to day 5. Cyt and Daun PK parameters were not correlated with patient gender, age or race. Incidence of non-hematologic toxicity increased with dose and systemic exposure. CRs were observed in patients receiving doses of 32-134 units/m2 of CPX-351. The responses at 101 units/m2 and above appear to be more durable. The Cyt:Daun molar ratio remained near 5:1 for up to 48 hours on both study days for all dose levels. Conclusions: Cyt and Daun delivered in CPX-351 exhibited linear single dose and multiple dose PK and low inter-patient variability in plasma concentrations within dose groups. CPX-351 provides predictable, extended systemic exposure of elevated Cyt:Daun concentrations near a 5:1 molar ratio. The 100 unit/m2 dose is undergoing testing in Phase II studies. ![Figure][2] Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1292. doi:10.1158/1538-7445.AM2011-1292 [1]: #F1 [2]: pending:yes