Local chemotherapy of F98 rat glioblastoma with paclitaxel and carboplatin embedded in liquid crystalline cubic phases

Implanted drug carrier systems for retarded chemotherapy against gliomas are mainly based upon polymers containing nitrosoureas. The authors have developed an intracavitary carrier system of biodegradable liquid crystalline cubic phases encapsulating carboplatin and paclitaxel and studied it for release kinetics, antitumor activity, and survival prolongation. A total of 61 Fisher rats with F98 tumors were divided into six treatment groups at day 12 post-inoculation, receiving either no treatment, surgery with partial tumor resection, or partial resection with implantation of cubic phases containing either paclitaxel and carboplatin, paclitaxel alone, carboplatin alone, or no drug. Animals were killed for tumor size analysis at day 21 post-inoculation (n=28) or were included in survival studies (n=33). Additional 12 animals received a paclitaxel/carboplatin application and were killed at different time intervals (6 h, 24 h, 48 h, 5 d, 7 d, 10 d post-agent application) for in vivo diffusion studies. Animals from the paclitaxel/carboplatin group showed a significantly smaller tumor (mean 3.25 mm2 ± SD 1.79 mm2) than animals from the control group (15.30 ± 5.86 mm2; P=0.0031), animals having received the empty matrix (11.62 ± 6.66 mm2; P=0.0241), and animals after tumor resection without implantation (20.87 ± 3.56 mm2; P ≤ 0.0001). There was no significant difference in survival. Carboplatin was found in brain tissue at 6 h, paclitaxel was found at up to 48 h after implantation at 3 mm distance. Biodegradable crystalline cubic phases embedding cytotoxic drugs as paclitaxel and carboplatin might play an important role in local glioblastoma treatment.