The use of submicron/nanoscale PLGA implants to deliver paclitaxel with enhanced pharmacokinetics and therapeutic efficacy in intracranial glioblastoma in mice

Abstract

Pharmacokinetics and therapeutic efficacy of submicron/nanoscale, intracranial implants were evaluated for treating malignant glioblastoma in mice. 9.1% (w/w) paclitaxel-loaded polylactide-co-glycolide (PLGA) nanofiber discs (F3) were fabricated and characterized for morphology and size distribution. Along with F3, three other formulations, 9.1% (w/w) paclitaxel-loaded PLGA submicron-fiber discs (F2), 16.7% (w/w) paclitaxel-loaded PLGA microspheres entrapped in hydrogel matrices (H80 and M80) were intracranially implanted in BALB/c mice and the coronal brain sections were analyzed for bio-distribution of paclitaxel on 14, 28 and 42 days post-implantation. BALB/c nude mice with intracranial human glioblastoma (U87 MG-luc2) were used in the therapeutic efficacy study. Animals were randomized to intracranial implantation of F3 and H80 with paclitaxel dose of 10mg/kg, placebo F3, placebo H80, weekly intratumoral injection of Taxol (10mg/kg) or no treatment and the treatment response was analyzed by bioluminescence imaging and histological (H&E, Ki-67) examinations. Enhanced, therapeutic paclitaxel penetration (approximately 1 microm) in the mouse brain up to 5mm from the implant site even after 42 days post-implantation from F3 and H80 was confirmed and deduced to be diffusion/elimination controlled. F3 and H80 demonstrated significant (approximately 30 fold) tumor inhibition and significantly low tumor proliferation index after 41 days of treatment in comparison to sham and placebo controls. The submicron/nanoscale implants are able to demonstrate optimal paclitaxel pharmacokinetics in the brain/tumor with significant tumor inhibition in a glioblastoma xenograft model in mice and hence could be potentially useful to treat highly recurrent GBM.