Immune checkpoint inhibitor therapy-related pneumonitis: effect on pulmonary function testing

SESSION TITLE: Diffuse Lung Disease Posters 5 SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/11/2023 12:00 pm - 12:45 pm PURPOSE: Immune checkpoint inhibitors (ICIs) have become the mainstay treatment for numerous malignancies. With their widespread use, the prevalence of ICI pneumonitis has risen becoming increasingly recognized as an important morbidity and risk factor for mortality. Scarce data exists on how ICI pneumonitis affects pulmonary function testing (PFT). METHODS: A retrospective study was conducted of patients diagnosed with ICI pneumonitis at the Mayo Clinic from 2014-2022. The patient cohort was obtained using Mayo Clinic’s informatics tool, Advanced Text Explorer, with keywords “pneumonitis” AND “immunotherapy” (n=848). All cases were reviewed by a pulmonologist to confirm the diagnosis yielding 170 patients. Excluded patients had alternative diagnoses (e.g. pneumonia, radiation pneumonitis, interstitial lung disease). Grading of pneumonitis was defined in accordance with ASCO guidelines (Schneider et al. 2021). Descriptive statistics were performed with chi-square statistics used to examine the association between ICI pneumonitis grade and all-cause mortality after diagnosis. Paired t-tests were used to evaluate the impact ICI pneumonitis (regardless of treatment) had on PFT values. RESULTS: A total of 170 patients with ICI pneumonitis were reviewed. The severity of ICI pneumonitis was as follows: grade 1 (n=17, 10%), grade 2 (n=85, 50%), grade 3 (n=53, 31%), grade 4 (n=11, 7%) and grade 5 (n=4, 2%). There was a significant relationship (α= 0.05) between mortality and ICI grade (x2= 44.04, df= 4, p<0.001). From 170 patients, 44 had pre- and post-diagnosis spirometry. All PFT values (FEV1, FVC, TLC, and corrected DLCO) were significantly lower after ICI diagnosis compared to baseline values (p<0.01 for all comparisons). When categorized by severity, significant reductions in FVC, TLC, and DLCO were only present in grade 2 and 3 disease (p<0.01). Patients with grade 1 had no significant change in any PFT metric. Grades 4 and 5 pneumonitis were unable to be analyzed due to low numbers of pre- and post-diagnosis PFTs. CONCLUSIONS: Our results suggest that the severity of ICI pneumonitis may play a role in the effects on pulmonary function. CLINICAL IMPLICATIONS: Our data suggests that, as expected, pulmonary function is affected by ICI pneumonitis. Baseline PFTs should be considered in patients starting ICI as well as at the time of ICI pneumonitis diagnosis and after pneumonitis treatment to assess treatment response. Further studies are needed to assess lung function recovery and whether baseline PFTs can be used to risk stratify patients. Most importantly, prompt recognition of pneumonitis is critical to avoid a reduction in pulmonary function and overall morbidity and mortality. DISCLOSURES: No relevant relationships by Ashley Egan No relevant relationships by Robert Haemmerle No relevant relationships by Antonious Hazim No relevant relationships by KONSTANTINOS Leventakos No relevant relationships by Keith McConn No relevant relationships by John McGlothlin No relevant relationships by Irene Riestra Guiance No relevant relationships by Gordon Ruan