Translymphatic Chemotherapy by Intrapleural Placement of Gelatin Sponge Containing Biodegradable Paclitaxel Colloids Controls Lymphatic Metastasis in Lung Cancer

Abstract

As a means of treating lymphatic metastasis from lung cancer, the pharmacokinetics and therapeutic effects of an intrapleural (ipl) implantable drug delivery system consisting of a gelatin sponge impregnated with polylactide-co-glycolide paclitaxel (PLGA-PTX) microspheres were studied. PLGA-PTX with 7% (w/w) drug loading were incorporated into gelatin matrix. The pharmacokinetics were studied in rats with one of the following regimens: (a) Taxol 8 mg/kg by i.v. injection; (b) Taxol 8 mg/kg ipl; (c) PLGA-PTX (100 mg/kg) ipl; (d) sponge containing PLGA-PTX (100 mg/kg) ipl. PTX concentrations in lymph node and plasma were determined by liquid chromatography mass spectrometry, and the area under the curve (AUC) was calculated. Therapeutic efficacy was assessed in an orthotopic lung cancer model with tumor resection 14 days following tumor implantation. Animals were randomized to ipl placement of PLGA-PTX sponge, placebo sponge, or no treatment. Lymph node metastases were examined at 32 d. The results show that the mediastinal lymph node AUC was significantly higher with ipl. placement of PLGA-PTX sponge compared with i.v. and ipl administration of Taxol. This represents 100- to 400-fold increase of lymphatic drug exposure compared with i.v. dosing. Peak plasma concentration was significantly reduced in the PLGA-PTX sponge group compared with i.v. dosing. PLGA-PTX particles were microscopically identified in lymphatic tissue and resulted in an 80% reduction of lymphatic metastasis compared with controls. Translymphatic-targeted drug delivery significantly decreases lymphatic metastasis in an orthotopic lung cancer model. This effect may be attributable to the improved distribution of PTX to the lymphatic system.