Pharmacokinetics, Tumor Accumulation and Antitumor Activity of Nanoliposomal Irinotecan Following Systemic Treatment of Intracranial Tumors

Abstract

We sought to evaluate nanoliposomal irinotecan as an intravenous treatment in an orthotopic brain tumor model. Nanoliposomal irinotecan was administered intravenously in the intracranial U87MG brain tumor model in mice, and irinotecan and SN-38 levels were analyzed in malignant and normal tissues. Therapy studies were performed in comparison to free irinotecan and control treatments. Tissue analysis demonstrated favorable properties for nanoliposomal irinotecan, including a 10.9-fold increase in tumor AUC for drug compared with free irinotecan and 35-fold selectivity for tumor versus normal tissue exposure. As a therapy for orthotopic brain tumors, nanoliposomal irinotecan showed a mean survival time of 54.2 versus 29.5 days for free irinotecan. A total of 33% of the animals receiving nanoliposomal irinotecan showed no residual tumor by study end compared with no survivors in the other groups. Nanoliposomal irinotecan administered systemically provides significant pharmacologic advantages and may be an efficacious therapy for brain tumors.