Checkpoint Inhibitor Pneumonitis Induced by Anti-PD-1/PD-L1 Therapy in Non-Small-Cell Lung Cancer: Occurrence and Mechanism Jianqiong Yin1†, Yuanjun Wu1†, Xue Yang1, Lu Gan2 and Jianxin Xue1,3,4* 1 Department of Thoracic Oncology, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China, 2 Research Laboratory of Emergency Medicine, Department of Emergency Medicine, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China, 3 Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, China, 4 Laboratory of Clinical Cell Therapy, West China Hospital, Sichuan University, Chengdu, China

Immune checkpointty inhibitors (ICIs), particularly those targeting programmed death 1 (PD-1) and anti-programmed death ligand 1 (PD-L1), enhance the antitumor effect by restoring the function of the inhibited effector T cells and produce durable responses in a large variety of metastatic and late patients with non-small-cell lung cancer. Although often well tolerated, the activation of the immune system results in side effects known as immune-related adverse events (irAEs), which can affect multiple organ systems, including the lungs. The occurrence of severe pulmonary irAEs, especially checkpoint inhibitor pneumonitis (CIP), is rare but has extremely high mortality and often overlaps with the respiratory symptoms and imaging of primary tumors. The development of CIP may be accompanied by radiation pneumonia and infectious pneumonia, leading to the simultaneous occurrence of a mixture of several types of inflammation in the lungs. However, there is a lack of authoritative diagnosis, grading criteria and clarified mechanisms of CIP. In this article, we review the incidence and median time to onset of CIP in patients with non-small-cell lung cancer treated with PD-1/PD-L1 blockade in clinical studies. We also summarize the clinical features, potential mechanisms, management and predictive biomarkers of CIP caused by PD-1/PD-L1 blockade in non-small-cell lung cancer treatment. (Articolo completo: Frontiers in Immunology | www.frontiersin.org 2 April 2022 | Volume 13 | Article 830631)