Rate and risk factors of recurrent immune checkpoint inhibitor-related pneumonitis in patients with lung cancer

Background: Immune checkpoint inhibitors (ICIs) have become standard treatments for lung cancer patients. Immune checkpoint inhibitor-related pneumonitis (CIP) was the leading cause of death among ICIs-related adverse events (irAEs). Recurrent episodes of CIP without rechallenge of ICIs were reported in several cases and maybe a unique feature of CIP. Knowledge gaps remain regarding the rate and risk factors associated to CIP's recurrence.Methods: Data from 1,102 lung cancer patients receiving ICIs treatment between January 2016 and January 2021 were retrospectively collected and analyzed. CIP was diagnosed according to typical clinical features and/or new typical imaging changes. Recurrence of CIP (CIP-R) was defined as recurrent CIP after initial CIP improved after proper treatment. Logistic regression was used to assess risk factors associated with CIP recurrence.Results: Eighty out of 1,102 (7.26%) patients were diagnosed with CIP. Twenty of those 78 (25.64%) patients suffered CIP-R, 2 patients died and were therefore excluded from the denominator. The median onset of initial pneumonitis for patients without and with recurrence was 3.49 months [interquartile range (IQR), 0.26-31.93 months] and 2.78 months (IQR, 1.22-20.93 months), respectively (P=0.48). The median interval duration between initial CIP and CIP-R was 1.54 months (IQR, 0.98-16.70 months). Recurrence of CIP was more common in males (P=0.03), squamous histology (P=0.016), and in patients who received chest radiotherapy (P=0.049). The duration of prednisolone equivalent dose >= 15 mg/day in CIP-R was significantly shorter, at 3.71 weeks (2.86-6.57 weeks) compared with 6.36 weeks in those without recurrence (IQR, 3.12-9.86 weeks) (P=0.001). Non-squamous histology [odds ratio (OR), 0.182; 95% confidence interval (CI): 0.038-0.860; P=0.031] and prolonged administration of prednisolone equivalent dose >= 15 mg/day for more than 4 weeks (OR, 0.082; 95% CI: 0.02-0.342; P=0.001) were independently associated with a decreased odds of CIP-R development.Conclusions: CIP-R in a real-world lung cancer cohort is not uncommon, both in patients with and without rechallenge of ICIs. A duration of prednisolone equivalent dose >= 15 mg/day of at least 4 weeks during the tapering process of corticosteroids were recommend in patients with CIP.