Case report: Caplacizumab without plasma exchange for severe thrombotic thrombocytopenic purpura.

A 45-year-old female Jehovah's Witness presented with transient expressive aphasia, blurred vision, and dizziness for several hours. A complete blood count (CBC) showed anemia (hemoglobin: 6.3 g/dL), thrombocytopenia (platelet count: 21 × 103/µL), and undetectable haptoglobin. The peripheral smear revealed schistocytes, confirming microangiopathic hemolytic anemia; immune-mediated thrombotic thrombocytopenic purpura (iTTP) was confirmed with an ADAMTS13 level of less than 5% and a positive ADAMTS13 inhibitor screen. Treatment with high-dose corticosteroids was urgently initiated, but the patient and her husband declined plasma exchange based on their beliefs as Jehovah's Witnesses. The patient acutely decompensated, requiring intubation, with worsening of laboratory values (hemoglobin: 3.8 g/dL; platelet count: 9 × 103/µL), elevated serum troponin, and renal and hepatic compromise. In addition to rituximab and intravenous immune globulin, caplacizumab therapy was undertaken. The patient's condition improved clinically, but from a laboratory value perspective, 1 month after caplacizumab initiation, her ADAMTS13 level remained less than 5%. Further immunosuppression with intravenous cyclophosphamide was initiated, which resulted in complete normalization of ADAMTS13 activity. This is the first report of caplacizumab use in a Jehovah's Witness patient with TTP with severe neurological compromise to the point of necessitating intubation and with this degree of anemia. With the eventual addition of cyclophosphamide therapy, we observed complete recovery of this critically ill patient without the use of plasma exchange in the treatment course.