Real-world data of the use and experience of caplacizumab for the treatment of acquired thrombotic thrombocytopenic purpura: Case series

Purpose: Caplacizumab was licensed for acquired thrombotic thrombocytopenic purpura (aTTP) based on prospective controlled trials. Real-world evidence is crucial in rare diseases. We aim to describe a patient population with aTTP, receiving caplacizumab in a real-world setting, reporting their outcomes, including safety and tolerability, and contrasting them with a historical cohort from our center. Methods: We describe data collected retrospectively from 2012 to 2022 for 16 patients with aTTP (8 received caplacizumab and 8 the historical standard-of-care). Patients' characteristics and outcomes were compared between groups. Results: Patients' demographic and baseline characteristics were similar in both groups. Caplacizumab led to a rapid normalization of the platelet count of 3.5 (IQR, 2-6) versus 16 (IQR, 9.5-23.5) days in the historical cohort: (p = .002). The median number of plasma exchanges and the length of days requiring them, between the caplacizumab group versus the historical cohort, was 6 (IQR, 6-10) versus 19.5 (IQR, 12.5-29.5) plasma exchanges (p = .006); and 9 (IQR, 8.5-13.5) versus 22 (15-31) days (p = .049), respectively. There were no refractory cases in the caplacizumab group in comparison with 37.5 % in the historical cohort. None of patients treated with caplacizumab experienced a recurrence after 1081 (IQR, 511-3125) days of follow-up. Safety was in line with data reported in clinical trials, with mild adverse events (mostly grade & LE;2). Conclusion: We provided real-world evidence in the treatment of aTTP, confirming the results obtained in clinical trials. Caplacizumab reduced the time to platelet count recovery and the number and length of plasma exchanges.