Association between pre-treatment chest imaging and pulmonary function abnormalities and immune checkpoint inhibitor pneumonitis.

Background: Immune checkpoint inhibitors (ICIs) are a first-line treatment for various metastatic solid tumors. Pneumonitis is a potentially devastating complication of ICI treatment and a leading cause of ICI-related mortality. Here, we evaluate whether abnormal pre-treatment pulmonary function tests (PFTs) or interstitial abnormalities on computed tomography of the chest (CT chest) prior to ICI are associated with the development of ICI-pneumonitis (ICI-p).

Methods: We conducted a retrospective cohort study of consecutive patients who received at least one dose of ICI from 2011 to 2017 at The Ohio State University. Potential risk factors for ICI-p, including abnormal PFTs and CT chest, were recorded. These risk factors were compared between patients with and without pneumonitis.

Results: In total, 1097 patients were included, 46 with ICI-p and 1051 without. Ninety percent of patients had pre-treatment chest imaging, while only 10% had pre-treatment PFTs. On multivariable analysis, interstitial abnormalities and reduced total lung capacity (TLC) were significantly associated with development of ICI-p (hazard ratio of 42.42 [95% CI; 15.04-119.67] and hazard ratio of 4.04 [95% CI; 1.32-12.37]), respectively. No other PFT abnormality was associated with increased risk of ICI-p. There was no significant difference in overall survival in patients who did or did not develop ICI-p (p = 0.332).

Conclusions: Pre-existing interstitial abnormalities on CT chest and reduced TLC were strongly associated with developing ICI-p. Prospective studies are warranted to further explore the role of PFTs as a potential tool for identifying patients at highest risk for developing ICI-p.