Pneumonitis Incidence in Patients With Metastatic Non-small Cell Lung Cancer on Immunotherapy: A Systematic Review and Meta-Analysis

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, often diagnosed at the advanced stage (metastatic). Treatment options for metastatic NSCLC include radiotherapy, chemotherapy, target drug therapy, and immunotherapy. Immunotherapy (utilization of checkpoint inhibitors) boosts the immune system to recognize and destroy cancer cells. However, it is often associated with immune-related complications such as pneumonitis. This review aims to determine the incidence of pneumonitis in metastatic NSCLC patients treated with different immunotherapy drugs. PubMed, Cochrane Library, and Embase databases were scoured for randomized controlled trials (RCTs) until October 2023. Published RCTs with similar research objectives were included, while non-English articles, reviews, case reports, ongoing trials, non-randomized studies, conference abstracts, and studies on small cell lung cancer (SCLC) were excluded. The Cochrane risk-of-bias tool for randomized trials (RoB 2) was used to assess the risk of bias among the included studies. The statistical analyses were performed with the Comprehensive Meta-Analysis software. The subgroup analysis of the 16 included RCTs showed that metastatic NSCLC patients treated with nivolumab and pembrolizumab had a higher incidence of any grade pneumonitis than those treated with atezolizumab (4.5% and 5.1% vs. 1.6%, respectively). Similarly, the incidence of grade >= 3 pneumonitis was higher among patients receiving nivolumab (1.3%) and pembrolizumab (2.4%) than those receiving atezolizumab (0.7%). Furthermore, the subgroup analysis showed that patients with naive-treated NSCLC on immunotherapy had a higher incidence of any grade pneumonitis than those with previously treated NSCLC (6.5% vs. 3.9%). Treatment-naive patients recorded higher grade >= 3 pneumonitis incidences than those previously treated (3.1% vs. 1.3%). Programmed death 1 (PD-1) inhibitors (i.e., pembrolizumab and nivolumab) have higher incidences of pneumonitis than programmed death-ligand 1 inhibitors (atezolizumab).