Abstract
INTRODUCTION: In August 2018, the Japanese PMDA approved nivolumab, an immune checkpoint inhibitor, for previously treated, unresectable, advanced, or recurrent pleural mesothelioma (PM) based on the MERIT trial, a phase II study of 34 cases. However, concerns regarding limited evidence persist. METHODS: We retrospectively analyzed 83 patients with previously treated, unresectable, advanced, or recurrent malignant PM treated with nivolumab from August 2018 to May 2022. Efficacy was evaluated using overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) per modified RECIST criteria. Safety was assessed by treatment-related adverse events (TRAEs) according to CTCAE v5.0. PD-L1 expression was analyzed with the anti-PD-1 antibody (22C3). RESULTS: The median age was 73 years. Histological subtypes included epithelioid (60), sarcomatoid (15), biphasic (6), and unknown (2). Lines of treatment were 2nd (62), 3rd (13), and 4th or later (8). Partial response was seen in 16 patients, stable disease in 30, progressive disease in 29, and not evaluable in 8, with an ORR of 19.3% and a disease control rate of 55.4%. Median PFS and OS were 5.1 and 12.4 months, respectively. TRAEs occurred in 45 patients (54.2%), with grade ≥3 in 6 (7.2%) and one treatment-related death. PFS correlated with male gender, TRAEs, and good performance status (PS: 0-1), while OS correlated with PS. CONCLUSION: Nivolumab demonstrated efficacy and safety in clinical practice, supporting its use in patients with good PS, even in later lines.