A study focused on the biological effects of pleural fluid in mesothelioma, and an analysis of the feasibility of a personalised bench-to-bedside pathway for mesothelioma treatment

Abstract

Background and aims: Malignant pleural mesothelioma (MPM) carries a poor prognosis and more than half MPM patients do not show disease response to cancer drugs. A more personalised effective approach to MPM treatment is desirable, and the timely development of personalised MPM cell cultures and analysis of drug response/resistance profiles may help guide clinical management of MPM. MPM or pleural metastases often present with malignant pleural effusion (MPE). There is early pre-clinical evidence of potential biological properties of MPE fluid that may contribute to cancer cell proliferation. Current management of MPE is symptomatic. Should pleural fluid have biological properties, management of MPE may shift towards a more aggressive approach in order to impact on patient survival. This study aimed to: a) Analyse a database of MPM patients to explore associations between pleural fluid and survival. b) Develop patient-derived MPM cell cultures from MPE fluid, with high success rate; develop cell cultures from the same patient at different time points. c) Analyse the effects of pleural fluid on cancer cells in vitro. d) Provide a description of potential future directions of research. e) Conduct drug screening assays on MPM cell cultures, to assess feasibility of a bench-to-bedside pathway from MPM MPE fluid to drug resistance/response profiles which would be clinically relevant and useful. Methodology: a) Data on MPM patients (in 3 UK pleural units) were collected and analysed. b) MPM cell cultures were established from MPE samples. c) Cells from established, patient-derived, cancer cell cultures were seeded in pleural fluid, and cell proliferation monitored. Primary MPM cell culture was attempted in 100% MPE fluid, with primary MPM cell culture in complete medium as a control. d) A literature review of animal models studying MPE and MPM, and an experimental model I was involved in the development of, were used to design animal models utilising indwelling pleural catheters to investigate the effects of MPE on pleural tumour growth and on chemotherapy response in vivo. e) DNA sequencing and drug screening were performed on MPM cell cultures. Discussion and conclusions: Pleurodesis success appears to be associated with improved survival. It is unclear whether prolonged exposure to MPE affects MPM tumour proliferation in humans. This data serves to highlight the need for prospective data and can be used to guide the direction of future study designs. MPM cell cultures were established from MPE fluid samples with a high success rate, had recognisable malignant features on cytology, included cancer stem cells, and had similar variant profile to MPM tumours. The cell cultures were used to perform quality drug screening assays and DNA sequencing, and the feasibility of a bench to bedside pathway was shown, with the cell cultures as potential tools to refine patient management in MPM. Cancer cells proliferate strongly in 100% pleural fluid, and to our knowledge this is the first demonstration of this effect, which potentially reflects the intrapleural environment in vivo. Although the mechanism is unclear, any form of human pleural fluid (malignant, nonmalignant, transudate, exudate) appears to have this effect, and this has potentially significant mechanistic and clinical implications. Moreover, this is the first time that primary cancer cell culture has been performed using pleural fluid alone.