The purpose of this study was to evaluate and compare plasma pharmacokinetics, lung tissue concentration, and the potential toxicity of drug eluting beads loaded with irinotecan (DEB-IRI) in a sheep pulmonary artery chemoembolization (PACE) model. Sheep (n = 24) were embolized with DEB-IRI loaded with different doses (0, 20, 50, or 100 mg). Direct pulmonary artery (PA) injections of irinotecan were also performed at two doses (50 or 100 mg; n = 4 sheep). Irinotecan was quantified in plasma and lung tissue (liquid chromatography-fluorescence detection); pathological examination of lungs was performed 4 days or 4 weeks after PACE. Irinotecan was detected in the systemic circulation within a few minutes after PACE, for several hours in DEB-IRI 20 and DEB-IRI 50 groups, and for 24 hours for DEB-IRI 100. Both Cmax and AUC values increased significantly with dose (p = 0.0078 and p = 0.0008, respectively) after PACE. Cmax and AUC values were significantly reduced (by 80%, p = 0.0036, and by 50%, p = 0.0393, respectively) after PACE than after direct PA injection. Irinotecan was not detected in tissue 4 days after PACE. No sign of lung toxicity was observed, except a limited hemorrhagic angionecrosis seen 4 days after PACE with DEB-IRI 100. Inflammatory response on beads was moderate in all DEB-IRI groups. Compared to other routes of administration, DEB loaded with irinotecan at doses up to 100 mg was well tolerated. DEB loaded with 100 mg irinotecan seem a promising candidate for future PACE trials in patients.
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