Fatal myocarditis and rhabdomyolysis induced by nivolumab during the treatment of type B3 thymoma.

Immune checkpoint inhibitors including programmed death-1 inhibitors are promising agents for many types of malignancies; however, it is still an off-label choice for type B3 thymoma. We reported for the first time a patient with type B3 thymoma developed fatal myocarditis and rhabdomyolysis after one dose of nivolumab administration. The results from myocardial and muscle biopsies revealed extensive myocyte damage, T-lymphocytic infiltration and strongly expression of PD-L1 which confirmed the nivolumab-related immune-related adverse events (irAEs). The blood tests showed elevated levels of serum AChR-binding antibody and inflammatory cytokines, in addition abnormal lymphocyte subsets were noted. Our report suggested that administration of nivolumab in type B3 thymoma could cause rare but fatal myocarditis and rhabdomyolysis, over-expressed AChR-binding antibody and inflammatory cytokines may be potential biomarkers for irAEs.