Independent validation of progression-free survival rate at 9 and 18 weeks (PFSR-18, PFSR-9) as predictor for overall survival (OS) in patients with malignant pleural mesothelioma (MPM): EORTC 08052 study.

7584 Background: The increasing incidence and the plateau of current treatment outcomes in MPM necessitates development of new therapeutic approaches. Reliable and meaningful response assessment is difficult in phase II trials thus a primary endpoint based on progression free survival (PFS) rate at certain time point has been proposed (Greillier et al, 2011). EORTC 08052 was a phase II study in MPM where independent validation of PFSR-18 weeks was foreseen. We extend this to PFSR-9. Methods: Association of PFS and response with OS was assessed at two distinct time points; 9 and 18 weeks after registration. Landmarks method was used, PFS status (CR/PR/SD vs. PD) and response status (CR/PR vs. PD/SD) were determined at those time points. Cox regression and logrank test were performed and the corresponding c-indexes were calculated. Results: Of 82 registered patients, 28.4% achieved CR/PR and 77.8% had disease control (CR/PR/SD) as their best overall response. PFSR-18 and PFSR-9 were both strongly correlated...