Risk factors and immunomodulators use in steroid-refractory checkpoint inhibitor pneumonitis

Background Checkpoint inhibitor pneumonitis (CIP) that does not respond to corticosteroids is termed steroid-refractory CIP. We aimed to find risk factors of steroid-refractory CIP and evaluate the management strategies of immunomodulators (IMs). Methods Patients with CIP were identified between August 2019 and August 2022 retrospectively. Clinical characteristics, peripheral blood biomarkers, and radiologic images were collected. Results Among 1209 patients with solid tumor receiving programmed death (ligand)-1 antibody, 28 patients developed steroid-refractory CIP and 38 patients developed steroid-response CIP. Patients with steroid-refractory CIP had a higher proportion of previous interstitial lung disease (p=0.015) and grade 3–4 (p<0.001) at diagnosis. Otherwise, absolute neutrophil count (ANC), procalcitonin were higher and albumin was lower in steroid-refractory patients (ANC, p=0.009; procalcitonin, p=0.024; albumin, p=0.026). After multivariate analysis, grade 3–4 and higher ANC at diagnosis were confirmed to be independent risk factors for steroid-refractory CIP (grade, p=0.001; ANC, p=0.046). For grade 2 steroid-refractory CIP, additional IMs did not affect the prognosis (p=1.000). However, additional IMs reduced the risk of deterioration significantly in grade 3–4 steroid-refractory CIP (p=0.036). Conclusions Grade 3–4 and higher peripheral blood ANC at diagnosis are associated with higher risk of steroid-refractory CIP. The use of additional IMs improves the outcome of grade 3–4 steroid-refractory CIP. These results can offer new insights to the decision-making of CIP management.