Personalised treatment of patients with immune thrombotic thrombocytopenic purpura

Background. Treatment of immune thrombotic thrombocytopenic purpura (iTTP) includes plasma exchange (PEX) and immunosuppression (glucocorticoids and rituximab). The addition of caplacizumab to therapy has improved treatment outcomes in iTTP. However, the available therapies focus on the duration of drug administration and clinical response rather than ADAMTS13 activity. Aim. To evaluate the efficacy of therapy for iTTP targeting ADAMTS13 activity. Materials and methods. Treatment of patients with iTTP was started with PEX, prednisolone (1 mg/kg) and caplacizumab (10 mg/day). PEX was discontinued after an increase of platelet count 150×109/L. Only after PEX cessation treatment with rituximab (375 mg/m2 weekly) was started. Caplacizumab was discontinued when partial remission (ADAMTS13 20%) was achieved. Rituximab and glucocorticoids were discontinued when complete remission (ADAMTS13 40%) was achieved. Platelet count, schistocyte count, haemoglobin, haptoglobin, lactate dehydrogenase activity, ADAMTS13, ADAMTS13 inhibitor titre, number of PEX, plasma volume replaced, time to increase platelet count 150×109/L, achievement of partial and complete remission were analyzed. Data are presented as median and interquartile range. Results. From 2021 to 2025, the diagnosis of TTP was confirmed in 102 patients. 35 patients were included in the study. Platelet counts 150×109/L were achieved after 4 (3–5) PEX procedures in 4 (3–4.5) days. In total, 11 395 (7241–16 343) ml of plasma were exchanged. Partial remission was achieved in 100% of patients, the duration of caplacizumab therapy was 23 (12–30) days. Rituximab was administered from 4 to 8 times (median 4), complete remission was achieved in 33 out of 35 patients, 2 patients achieved only partial remission, they were treated with bortezomib and 1 with anti-CD38 monoclonal antibody. The probability of complete remission was 97.1%. Conclusion. The duration of therapy with caplacizumab, rituximab and glucocorticoids in patients with iTTP should be determined by the achievement of target ADAMTS13 activity.