Intrapleural polymeric films containing cisplatin for malignant pleural mesothelioma in a rat tumour model: a preliminary study

Objective: This study aims to investigate the effect of intrapleural polymeric films containing cisplatin on the local recurrence of malignant pleural mesothelioma in a rat tumour model. Methods: An orthotopic rat recurrence model of malignant pleural mesothelioma was used. Five animals per group were evaluated. Polymeric films (4.5 cm diameter) for the local delivery of anticancer drug were constructed: hyaluronate, chitosan and the combined dual-layer polymers were loaded with cisplatin at a concentration of 100 mg m-2. Animals without any adjuvant therapy were used as control. Mesothelioma cells were injected subpleurally in the anaesthetised rats. Six days later, a pleural tumour of 5.5 mm was resected and a left pneumonectomy and pleural abrasion were performed. Thereafter, the cisplatin-loaded and unloaded films or cisplatin solution were intrapleurally applied, according to randomisation. After 6 days, animals were euthanised and organs harvested for morphological and histological evaluations. The primary endpoint was the volume of tumour recurrence. The secondary endpoints were treatment-related toxicity; cisplatin serum concentration evaluated at different time points; and cisplatin concentration in the pleura measured at autopsy. Analysis of variance (ANOVA) was used for statistical analysis. Bonferroni correction was applied for comparison between all groups. Results: Tumour volume was significantly reduced in the hyaluronate cisplatin and hyaluronate-chitosan cisplatin groups in comparison to control groups (p = 0.001 and p < 0.0001, respectively). Animals treated with hyaluronate-chitosan cisplatin had a tumour recurrence significantly lesser than animals treated with cisplatin solution (p = 0.003) and hyaluronate cisplatin (p = 0.032). No toxicity related to the different treatments was observed. On postoperative days 1 and 2, cisplatin was detected in the serum at a concentration six- and sevenfold significantly higher in the hyaluronate cisplatin and