Iatrogenic hemorrhage and extensive venous thromboembolism during iTTP treatment with caplacizumab-A case report.

Caplacizumab reduces the need for therapeutic plasma exchange (TPE) during treatment for thrombotic thrombocytopenic purpura (TTP), associates with fewer required TPE, and shortens hospital stay. It is therefore recommended as part of standard care. However, the treatment effects on hemostasis may complicate initial management. We present a case of a woman with immune-mediated TTP who developed an intrathoracic hemorrhage on caplacizumab treatment after replacement of her central venous catheter. Reduced von Willebrand factor (vWF):glycoprotein Ib mutant (GPIbM) activity was reversed using vWF concentrate and the bleeding stopped. Unfortunately, vWF substitution in combination with caplacizumab discontinuation likely contributed to subsequent extensive venous thromboembolism. Risk-reducing strategies against both bleeding and thrombosis are crucial during caplacizumab treatment, and emergency vWF substitution increases the already high risk of thrombosis associated with TPE.