Previously, pre‐clinical dose finding tolerance study in a human xenograft pancreatic cancer model of intravenous liposomal curcumin determined 20 mg/kg TIW was to be the optimum dose and schedule for anticancer activity. Follow up pharmacokinetic and dose finding studies in a health rat model evaluated doses up to 40 mg/kg was not associated with weight loss, hematological, serologic, or dose‐limiting toxicity. In canine model, a single‐dose finding tolerance study ranging from 2 mg/kg up to 40 mg/kg revealed the maximum tolerated dose (MTD) of liposomal curcumin to be 20 mg/kg or 540 uMol/L of curcumin maximal blood concentration. Toxicity observed at this dose level was characterized by a brief single episode of reversible hematuria. The dose limiting toxicity was observed at a single dose of 40 mg/kg of liposomal curcumin. Following dose on day 1, life threatening toxicity followed within 48 hours with the dogs exhibiting irreversible acute hemolysis with hematuria, over 60% blood loss, and associated serologic abnormalities. A control cohort of dogs infused with the same quantity of liposome contained in the 40/mg/kg dose was without ensuing toxicity. These changes suggest the mechanism of hemolysis following 40mg/kg curcumin is due to an oxidant effect. Following acute hemolysis, the iron chelation activity of curcumin could contribute to unremitting anemia by blocking iron reutilization. In conclusion, at concentrations below the canine MTD of 20 mg/kg, curcumin acts as an anti‐oxidant, and acts as a pro‐oxidant at higher concentrations. The disparity between rodent and canine sensitivity to liposomal curcumin may be due to species differences in pharmacokinetics and/or curcumin metabolism. Ongoing study will define liposomal curcumin pharmacokinetic parameters at the MTD in canine mode as well define tolerability of multiple dosing in dogs. In addition hematological studies are being conducted to determine the mechanism of hemolysis that was observed at higher dose levels and identify potential biomarkers for predicting toxicity. Preliminary data suggests liposomal curcumin will have promising anticancer activity.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A29.