Nivolumab in pretreated pleural mesothelioma: Results from an observational real-world study of patients treated within the AIFA 5% Fund.

Background: Pleural mesothelioma is a rare cancer with a dismal prognosis and few therapeutic options, especially in the pretreated setting. Immunotherapy with checkpoint inhibitors as single agents yielded interesting results in refractory pleural mesothelioma, achieving a response rate between 10-20%, median progression-free survival of 2-5 months and median overall survival of 7-13 months.

Patients and methods: A retrospective, multi-institutional study of pleural mesothelioma patients treated with nivolumab in second and further line was performed. The endpoints of the study are response rate, disease control rate, progression free survival and overall survival.

Results: Sixty-five patients with pleural mesothelioma treated with nivolumab in second and further line were enrolled at seven Italian institutions. The response rate was 8%, disease control rate was 37%, median progression free survival was 5.7 months (95% CI: 2.9-9.0) and median overall survival was 11.1 (95% CI 6.2-19.9) months. A higher neutrophils and neutrophils to lymphocytes ratio at baseline were associated with worse prognosis.

Conclusion: Nivolumab as a single agent is fairly active in a cohort of unselected pretreated pleural mesothelioma patients. Further investigations on clinical and translational factors are needed to define which patient might benefit most from nivolumab treatment in pleural mesothelioma.