ICI-induced myocarditis results from T-cell-mediated cytotoxicity against shared cardiac/neuromuscular antigens, amplified by PD-1/PD-L1 blockade.3Biomarker Profile: Marked elevation of cardiac-specific troponin (TnI) and NT-proBNP reflects acute myocardial injury, inconsistent with chronic MG pathology. The gene discussed is CD274; the disease is myasthenia gravis.