Post Approval Experience with Caplacizumab for Acquired Thrombotic Thrombocytopenic Purpura at a Single Institution

Caplacizumab prevents platelet adhesion and has been approved for acquired thrombotic thrombocytopenic purpura (aTTP). This study was retrospective, including all patients diagnosed with aTTP and treated with caplacizumab since commercial availability in 2019 until 28 February 2021 at a single academic hospital with no exclusion criteria. Results used definitions for outcomes in aTTP from the International Working Group Consensus. Ten patients with aTTP received caplacizumab. The median age was 52 years. Six (60%) patients had refractory aTTP while 4 (40%) had newly diagnosed aTTP. The median laboratory values prior to therapy demonstrated: platelet count (PC) 29/uL, LDH 518 U/L (182-1850), ADAMTS13 activity 3% and ADAMTS13 inhibitor 1.4 BU. Everyone received glucocorticoids, rituximab, therapeutic plasma exchange (TPE) and caplacizumab. The median number of TPE was 12 days. Caplacizumab was started at a median of 5 days after the first TPE and the median treatment duration was 31 days. Normalization of PC, LDH and ADAMTS13 activity in days were 5, 3.5, and 32.5, respectively. Six (60%) patients achieved complete response, 3 (30%) had refractory disease and 1 (10%) had relapsed aTTP. No subject suffered abnormal bleeding, or thrombotic event. There were no deaths. Caplacizumab with TPE, glucocorticoids and rituximab was a safe and effective therapy for aTTP.