Frequency and Consequences of Immune Checkpoint Inhibitor–Associated Inflammatory Changes in Different Organs: An Autopsy Study Over 13 -Years
Umberto Macciò, Andreas Wicki, Frank Ruschitzka, Felix Beuschlein, Sibylle Wolleb, Zsuzsanna Varga, H. Moch
Abstract
Although immune checkpoint inhibitors (ICIs) have revolutionized modern oncology, they are also associated with immune-related adverse events (irAEs). Previous histopathologic descriptions of organ-related inflammatory changes do not consider systemic effects of ICIs, because of the absence of comprehensive autopsy studies. We performed a retrospective study on 42 whole-body autopsies of patients treated with ICIs from January 2011 to March 2024 to determine the frequency, organ distribution, and morphology of ICI-associated inflammatory changes as well as their clinical relevance. Twenty-three of 42 (54.8%) patients presented irAEs with inflammatory changes in at least one organ. Most frequent irAEs were ICI-related hypophysitis (N = 12; 28.6%), myocarditis (N = 8; 19.0%), pneumonitis (N = 5; 11.9%), hepatitis (N = 6; 14.3%), and adrenalitis (N = 5; 11.9%). ICI-related inflammation was mainly characterized by lymphohistiocytic and macrophage-rich tissue infiltrates, whereas a granulomatous "sarcoid-like" reaction was observed in 1 patient. Cause of death was attributable to ICI therapy in 7 (16.7%) patients, with ICI-associated myocarditis as the most common cause of death (N = 5; 71.4%). Clinically, irAEs were unsuspected in 5 of 7 ICI-related deaths (71.4%). Among irAEs, myocarditis has been clinically undiagnosed in 5 out of 8 cases (62.5%). Encephalitis was identified only at autopsy in all cases (N = 2). Hypophysitis was clinically unsuspected in 8 of 12 (66.7%) cases. Patients who died from irAEs developed more frequently a complete tumor regression than patients who died from other causes (P = .018). Of note, ICI-related myocarditis and pneumonitis were both associated with a systemic occurrence irAEs. Our study demonstrates that some irAEs, especially myocarditis, hypophysitis, and encephalitis, are clinically underdiagnosed. Autopsy remains a valuable tool to monitor diagnostic accuracy and therapeutic side effects in patients who died under ICI therapy.