A systematic review and meta-analysis of trials assessing PD-1/PD-L1 immune checkpoint inhibitors activity in pre-treated advanced stage malignant mesothelioma

Introduction: Advanced stage malignant mesothelioma (asMM) patients have poor prognosis. Several trials investigated the role of programmed cell death protein-1 (PD-1) and its ligand 1 (PD-L1) immune checkpoint inhibitors (ICIs) in pre-treated asMM. Methods: A systematic review of the literature of clinical trials testing single-agent anti PD-1/PD-L1 ICIs in pretreated asMM was performed. Objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS) and overall survival (OS) data were extracted. The predictive role of PD-L1 was assessed. Results: We selected 13 studies including 888 patients. ORR and DCR were 18.1% (95% confidence interval [CI] 13.9-22.8%) and 55.4% (95% CI: 48.1-62.5%), respectively. Median PFS and OS ranged from 2.1 to 5.9 and from 6.7 to 20.9 months, respectively. ORR according to PD-L1 was 27.0% (95% CI: 18.7-36.2%). Conclusions: Anti-PD-(L)1 ICIs might be considered a treatment option for chemotherapy-resistant asMM, even if reliable predictive factors are still lacking.