An open-label study to evaluate dose and cycle dependence of the pharmacokinetics (PK) of pegylated liposomal doxorubicin (PLD)

Abstract

2012 Background: There are no definitive data in humans on the dose dependency and/or cycle dependency of the pharmacokinetics of PLD. The skin toxicity of PLD tends to worsen after several treatment cycles. Therefore, it is important to characterize the PK of PLD after 2 or more cycles. Methods: Fifteen patients with various solid tumors were randomized to two arms of treatment in an open-label study. Arm A received PLD at doses of 60, 30, and 45 mg/m2 in 3 successive cycles every 4 weeks (q4w). Arm B received PLD at doses of 30, 60, and 45 mg/m2 in 3 successive cycles q4w. Twelve patients, 6 on each arm, completed all three cycles and were fully evaluable. Plasma levels of doxorubicin were analyzed by HPLC and fluorimetry following a previously published method (J Chromatogr B, 779:259–69, 2002) with minor modifications. PK analysis was done by non-compartmental method. The following parameters were obtained: Cmax, AUC∞, terminal half-life (T1/2), and Clearance (CL). The paired t test was used for statistical analysis. Results: There was no significant difference in the parameters examined when the dose was increased from 30 to 60 mg/m2. However, when we analyzed the effect of cycle number on the PK, we found a gradual and significant inhibition of CL when patients advance from the 1st through the 3rd cycle of PLD (p=0.0003), with a mean increase of 44% in AUC/mg dose (p=0.0011). Cmax and T1/2 mean values increased by 17% and 18% respectively between the 1st and 3rd cycles, but only the increase in T1/2 was statistically significant (p=0.0127). Conclusion: While the PK of PLD is not dose-dependent within the dose range of 30 to 60mg/m2, there is evidence of a cycle-dependent effect that results in inhibition of CL when patients receive successive cycles of PLD. This effect may account for the delayed skin toxicity of PLD. These results suggest the need for dose adjustments of PLD to minimize the risk of toxicity, such as an initial high loading dose followed by reduced maintenance doses from the 2nd or 3rd cycle onwards. [Table: see text] [Table: see text]