Orphan Designation and Cisplatin/Hyaluronan Complex in an Intracavitary Film for Malignant Mesothelioma

Pleural mesothelioma is a lung diffuse tumor, whose complete resection is unlikely. Consequently, metastases reappear where the primary tumor was removed. This paper illustrates the orphan medicine designation procedure of an intracavitary cisplatin film and related pharmaceutical development aspects requested by the European Medicines Agency (EMA) in its Scientific Advice. Since cisplatin pharmacokinetics from the implanted film in sheep resulted substantially modified compared to intravenous administration, the formation of a cisplatin/hyaluronan complex had been hypothesized. Here, the interaction between sodium hyaluronate (NaHA) and cisplatin (CisPt) was demonstrated. Size exclusion chromatography qualitatively evidenced the complex in the film-forming mixture, only showing the NaHA peak. Atomic absorption spectroscopy of the corresponding fraction revealed platinum, confirming the interaction. Reverse phase HPLC quantified about 5% free cisplatin in the film-forming mixture, indirectly meaning that 95% was complexed. Finally, a study of CisPt release from the film assessed how CisPt/NaHA complex affected drug availability. In water, a medium without chloride ions, there was no release and the film remained intact for 48 h and longer, whereas the placebo film dissolved in 15 min. In 0.9% NaCl medium, the film became more soluble, dissolving within 3-4 h. However, cisplatin release was still controlled by the existing complex in solution until chloride ions displaced it. While the film modified its dissolution with aging, CisPt release remained unaffected (90% released in 48 h).