Early administration of caplacizumab combined with plasma exchange for thrombotic microangiopathy due to malignant hypertension: a case report.

Both thrombotic thrombocytopenic purpura (TTP) and malignant hypertension (MHT) present with thrombotic microangiopathy (TMA). Combination therapy with caplacizumab, anti-von Willebrand factor (VWF) A1 domain antibody, and plasma exchange (PE) has recently been highlighted as a novel therapeutic option for TTP. We treated a 51-year-old woman who showed severe hypertension, retinopathy, and acute kidney injury. Level of consciousness was clear on admission, but low-grade fever was observed. Laboratory tests showed normocytic anemia, thrombocytopenia, renal dysfunction, and a slight decrease in haptoglobin. Neither disseminated intravascular coagulation nor leukemia was diagnosed. The patient emergently received intravenous antihypertensive therapy, continuous hemodiafiltration, and sufficient blood transfusion. However, thrombocytopenia and oliguria remained despite control of blood pressure. On hospital day 8, administration of caplacizumab combined with PE was initiated before receiving results for a disintegrin-like and metalloprotease with thrombospondin type 1 motifs 13 (ADAMTS13) activity and inhibitor levels. We then administered caplacizumab for 5 days and performed 2 sessions of PE until confirming ADAMTS13 activity of 42% and absence of its inhibitor, contributing to increased serum hemoglobin and platelet levels with cessation of dialysis. Renal biopsy findings on hospital day 20 showed arteriolar nephrosclerosis and intimal hyperplasia in small arteries. To the best of our knowledge, this represents the first description of MHT-induced TMA treated with caplacizumab. MHT-induced TMA exhibiting symptoms of TTP tends to show poor renal prognosis, so early administration of caplacizumab with PE before receiving results for ADAMTS13 might prove beneficial for cases in which MHT complicated with TTP is suspected.