CD274 and malignant pleural mesothelioma: Of 25 patients receiving pembrolizumab in a single-arm phase I/II study (Keynote 28 (KN028)), the objective response rate was 20% in patients with PD-L1-positive malignant pleural mesothelioma (≥ 1% PD-L1-positive tumour cells by immunohistochemistry).