PD-1/PD-L1 Checkpoint Inhibitor Immunotherapy for Malignant Pleural Mesothelioma: Case Series and Literature Review

ABSTRACT Study design A retrospective, single-center, case series Introduction Malignant pleural mesothelioma (MPM) is a rare and aggressive neoplasm with poor prognosis. The combined cisplatin/pemetrexed regimen is the only regimen currently approved by the FDA. Immunotherapy with checkpoint inhibitors and other therapeutics are quickly becoming the preferred second-line therapy following incorporation into clinical practice guidelines in 2018 as a salvage therapy. Purpose of the study: To describe the use of PD-1/PD-L1 targeted therapy to manage MPM. Methods Retrospective chart review of patients with MPM treated at a single institution with pembrolizumab or nivolumab was performed. Clinical and pathologic information were extracted and clinical response rate and other outcomes were assessed. Results Twelve patients received pembrolizumab, and two patients received nivolumab. Patients were 43% male (6 out of 14), 64% non-Hispanic white (9 out of 14), and 93% epithelioid histological subtype (13 out of 14). Prior to immunotherapy, 36% had received surgical resection (5 out of 14), 36% had received radiotherapy (5 out of 14), and 93% received platinum-pemetrexed based chemotherapy (13 out of 14). Objective response rate was 21% (0 CR and 3 PRs), and disease control rate was 43% (3 PRs and 3 SDs). Time to progression ranged from Conclusion Based on this small series, real-world PD-1/PD-L1 targeted therapy appears to be a promising treatment for patients with MPM who have disease progression on systemic chemotherapy, consistent with small single arm clinical trials. Further investigation with multicenter, prospective longitudinal cohorts and/or randomized clinical trials may help identify which patients have the largest magnitude of benefit.