Immune checkpoint inhibitor-related myocarditis in patients with thymic epithelial tumors: a retrospective cohort analysis.

[BACKGROUND] Immune checkpoint inhibitor-related myocarditis (ICI-M) is increasingly recognized, but real-world data in thymic epithelial tumors (TET) remain limited.

[OBJECTIVE] To evaluate the clinical outcomes, focusing on ICI-M, in patients with TET receiving immune checkpoint inhibitors (ICI).

[METHODS] This retrospective study examined patients with TET at Guangdong Provincial People's Hospital in China from January 2018 to March 2024. We assessed the biomarker changes by comparing the baseline values to peak levels during ICI therapy. Clinical characteristics, disease progression, and outcomes of patients with ICI-M were also analyzed. To investigate the relationships between clinical factors or biomarkers and all-cause mortality, we performed univariable Cox regression analysis.

[RESULTS] Among 31 patients, 7 developed ICI-M, all in the thymoma subgroup (7/12, 58.3%). During a median follow-up of 494 days (262-858), 13 patients died (13/31, 41.9%), including 6 cardiovascular deaths (46.2% of deaths). N-terminal pro B-type natriuretic peptide (NT-proBNP) and Creatine kinase (CK) increased significantly during ICI therapy. In univariable Cox analysis, each doubling of CK was associated with higher all-cause mortality (HR 1.22 per doubling, 95% CI 1.01-1.47; P = 0.038).

[CONCLUSIONS] In this cohort of TET patients receiving ICI therapy, myocarditis occurred frequently in thymoma patients. Overall mortality was substantial in TET patients, with nearly half of the deaths attributable to cardiovascular causes. These findings highlight the need for vigilant cardiovascular monitoring in all TET patients undergoing ICI therapy and warrant confirmation in larger multicenter studies.