Treatment outcomes in malignant pleural mesothelioma: A single center experience of systemic therapies and biomarkers.

Abstract

e20070 Background: Malignant Pleural Mesothelioma (MPM) is a rare but fatal disease related to asbestos exposure, with historic survival in the order of 9 to 17 months. Chemotherapy is associated with only a modest benefit. The advent of immunotherapy has heralded significantly improved outcomes using checkpoint inhibitors in an as yet ill-defined cohort. We aim to identify predictive and prognostic biomarkers in a series of patients (pts) with MPM and describe survival data. Methods: A retrospective audit was undertaken of pts with MPM diagnosed between 2013 and 2017 at a single tertiary centre in Melbourne, Australia (Monash Health). Data relating to patient outcomes and clinicopathological features were obtained through medical reports. Further immunostains are being performed on archived tissue for PDL-1 status. Results: 65 pts were identified, of whom 52 (80.0%) were male. Median age was 73 years (range 44-90). 52 pts were noted to be ECOG 0-1. 42 pts (64.6%) were noted to have suspected asbestos exposure. Epithelioid MPM was the most common subtype, noted in 41 pts (63.1%) (table 1). 8 pts (12.3%) presented with stage IV disease. 16 pts (24.6%) received checkpoint inhibitor therapy, with 10 (63 %) in the second/third line setting. Median overall survival (OS) was 19.8 months (95% CI 13.3-26.3) in the whole cohort.Patient characteristics associated with poor OS were: presence of weight loss (P = 0.001), chest pain (p = 0.08) and ECOG 2 (p = 0.04). Pts with sarcomatoid histology who received immune checkpoint inhibitors in any line of treatment had significantly prolonged OS compared to other histologies. 3-year survival was 80% in this group while median OS was not reached (p = 0.04). This difference was not seen with other histologies. Conclusions: The evolving landscape of treatment in MPM appears to show promise in improving OS. In this unselected case series, our data is consistent with historic controls in terms of survival and prognostic factors. The finding of significantly improved survival with immune checkpoint inhibitors in the sarcomatoid histology is exciting and warrants further exploration. Further data on PDL1 status will be presented.