Immune checkpoint inhibitor-associated pneumonitis: focus on diagnosis and underlying mechanisms

Purpose of review This review aims to provide an updated overview of the diagnosis, risk factors, and treatment strategies for immune checkpoint inhibitor (ICI) pneumonitis, with a particular emphasis on its underlying pathophysiology. Recent findings Recent advances, such as single-cell RNA sequencing of bronchoalveolar lavage fluid and the identification of biomarkers, including autoantibodies, are enhancing our understanding of ICI-related pneumonitis. These findings suggest that both cell-mediated and humoral mechanisms contribute to the pathophysiology of the condition. Summary Pneumonitis can significantly limit the efficacy of life-saving cancer treatments, such as ICIs. Although corticosteroids are the first-line treatment according to guidelines, steroid-refractory pneumonitis remains common and is associated with high mortality. Emerging data is providing a more detailed understanding of the dysregulated immune response responsible for pneumonitis, which may guide the development of targeted therapies and direct future research efforts.