Risk factors for pneumonitis in patients with non-small cell lung cancer treated with immune checkpoint inhibitors plus chemotherapy: A retrospective analysis

Background Immune checkpoint inhibitor (ICI) therapy plus chemotherapy has become a standard of care for patients with advanced non-small cell lung cancer (NSCLC). Pre-existing interstitial lung disease (ILD) is a risk factor for drug-induced pneumonitis caused by chemotherapy or ICI monotherapy. However, clinical data in patients with pre-existing ILD who received ICI therapy plus chemotherapy are limited. This study aimed to identify the risk factors for drug-induced pneumonitis in patients with NSCLC treated with ICIs plus chemotherapy. Methods We retrospectively reviewed the medical records of 160 consecutive patients who were diagnosed with NSCLC and treated with ICIs plus chemotherapy at Aichi Cancer Center Hospital between December 2018 and November 2020. Patients with a prior history of ICI treatment or thoracic radiotherapy were excluded from the analysis. Results Among 125 patients, pre-existing ILD was observed in 20 patients (16.0%). Drug-induced pneumonitis developed in 17 patients (13.6%), with a median time to onset of 19.3 weeks (range, 1.6-108.9 weeks). In multivariate logistic analysis, pre-existing ILD (odds ratio = 19.07, p = 0.0001) and PEM exposure (odds ratio = 5.67, p = 0.022) were identified as risk factors for the development of drug-induced pneumonitis. Conclusions Pre-existing ILD and pemetrexed exposure are risk factors for drug-induced pneumonitis in patients with NSCLC.