Clinical insights on outcomes of corticosteroid administration in immune checkpoint inhibitor-induced pneumonitis by retrospective case series analysis

BACKGROUND: For the management of immune checkpoint inhibitor (ICI)-induced pneumonitis (ICI-pneumonitis), discontinuation of ICIs and high dose corticosteroid based on grade are generally recommended. The purpose of this study is to describe management and outcome of ICI-pneumonitis and explore what to consider when managing ICI-pneumonitis with or without corticosteroids in addition to grade. METHODS: We reviewed data of 706 cancer patients who were treated with ICIs and identified radiographically proven pneumonitis. The diagnosis of ICI-pneumonitis was established after excluding alternative aetiologies either by a bronchoscopy or a thorough examination of clinical features. The evaluation of the management and outcome of pneumonitis were evaluated according to the time of corticosteroid administration. RESULTS: ICI-pneumonitis developed in 16 patients (2.3%); nine grade 1, four grade 2 and three grade 3. Initially, 10 patients were spared from corticosteroid administration; fourpatients eventually received corticosteroid after 4 weeks of pneumonitis diagnosis due to clinical, radiographical aggravation and/or clinicians’ decision. The other sixpatients never received corticosteroid and improved or remained stable radiographically. When the four and sixpatients were compared, pneumonitis grade was similar, while the latter sixpatients had a later onset from initiation of ICIs (mean 37.48 weeksvs25.45 weeks), more prior lines of chemotherapy (median 2.5 vs 1.0 lines), higher proportion of current/ex-smokers (83.3% vs 50.0%), and fewer other accompanying immune-related adverse events (50% vs 75%). Time to improvement of pneumonitis was similar between the fourpatients who received delayed corticosteroid and fivepatients who received corticosteroid within 4 weeks(3.6 vs 2.5 weeks). CONCLUSIONS: Our analyses provide clinical insights that stratification of the patients is important in managing ICI-pneumonitis. Along with ICI-pneumonitis grade, more factors associated with the outcome need to be unravelled in the future.