Use of patient-derived organoids for pleural mesothelioma 3-D modeling

Defining preclinical models is of utmost importance for pleural mesothelioma (PM) to improve prognosis and predict therapeutic response. Using cells isolated from pleural fluid (PF) and diagnostic pleural biopsy (PB), we generated PM patient-derived organoids (PM-PDOs) and reactive-mesothelial (RM) patient-derived organoids (RM-PDOs) aiming at assessing the proportion of successful cultures both from PF and PB. We also compared the architectural and immune-histochemical features of PM-PDOs with those of parental tissues and evaluated the PM-PDOs response to chemoimmunotherapy. We obtained 11 successful PM-PDOs from 15 PF/PB (73.3%). The rate of success was higher in epithelioid PM (88.8%) compared with biphasic PM (40.0%) (<i>P</i> = 0.175), and when using PF (60.0%) compared with PB (20.0%) (<i>P</i> = 0.001). We also obtained 3 RM effective cultures from 6 asbestos-exposed patients (50%) with nonspecific pleuritis. Transcriptome analysis identified gene expression profile in PM-PDOs, which differentiate from RM-PDOs. PM-PDOs successfully maintained the histological architecture and molecular markers of their parental tumor tissues. The macrophagic component (CD68⁺ and CD163⁺) was an important component in RM-PDOs and was present in all three PM histotypes. Epithelioid PM-PDOs showed resistance to both Cis/PeMtx and pembrolizumab plus peripheral blood mononuclear cells (PBMCs), whereas both biphasic and sarcomatoid subtypes were sensitive to immunotherapy. Notably, immunotherapy induced an upregulation of PD-L1 expression and activated the STAT3/NF-κB signaling pathway, suggesting a mechanism of immune evasion. PF offers a valuable source of cancer and stromal cells to generate PDO, reinforcing its clinical utility for patients who cannot undergo invasive procedures.<b>NEW & NOTEWORTHY</b> Using cells isolated from pleural effusion and pleural biopsy, we established an efficient 3-D culture system for generating PM and reactive mesothelial (RM) patient-derived organoids. PM-PDOs expressed a specific gene profile, preserved the histological architecture, showing markers of the parental tumor tissues and recapitulated the tumor microenvironment (e.g., macrophages and tumor lymphocytes), which is an important factor influencing responses to therapy. This approach will be useful for drug screening, contributing to a more accurate selection of therapeutic options.