Emicizumab Associated Rhabdomyolysis in Hemophilia A

Emicizumab is increasingly the front-line treatment for patients with Hemophilia A with or without inhibitors. Rhabdomyolysis is a syndrome of muscle necrosis and release of intracellular muscle constituents into the circulation. Creatine kinase (CK) levels are typically markedly elevated, and muscle pain and myoglobinuria may be present. The severity of illness ranges from asymptomatic elevations in serum muscle enzymes to life-threatening disease associated with extreme enzyme elevations, electrolyte imbalances, acute kidney injury and disseminated intravascular coagulation. We present a case of an African American male with severe hemophilia A and history of factor VIII inhibitor, maintained on emicizumab prophylaxis, who developed rhabdomyolysis with a symptomatic hyperCKemia. To date, there is no known link between rhabdomyolysis to emicizumab. This report brings to light the possibility of symptomatic rhabdomyolysis as a potential side effect of emicizumab after moderate exertional activity.