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

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 10 mg/kg, placebo F3, placebo H80, weekly intratumoral injection of Taxol® (10 mg/kg) or no treatment and the treatment response was analyzed by bioluminescence imaging and histological (H&E, Ki-67) examinations. Enhanced, therapeutic paclitaxel penetration (∼1 μm) in the mouse brain up to 5 mm 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 (∼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.