OC 04.1 - Management of thrombotic thrombocytopenic purpura (TTP) without plasma exchange: an update on the Austrian experience

Background: Therapeutic plasma exchange (TPE) is still considered important for TTP, a severe disease caused by autoantibodies to ADAMTS13. However, exacerbations, refractory courses, and 10% mortality from organ failure are well known. Caplacizumab reduced the need for TPE and improved platelet recovery and survival. Recently, the successful treatment of patients with TTP only with caplacizumab and immunosuppression, but without TPE, has been reported.

Aims: Thus, we used a modified TTP management strategy, aiming to avoid TPE if platelet counts increased after a first dose of 10 mg caplacizumab, early addition of immunosuppression with steroids and rituximab, and continuing daily caplacizumab until ADAMTS13 increased >20%.

Methods: With this strategy 14 Austrian patients with TTP (3 male, 11 female, median age 51 years (range 29-75 yrs) and signs of severe organ dysfunction (high troponin, stroke, confusion, elevated creatinine) were treated. All patients had severe ADAMTS13 deficiency and detectable inhibitors.

Results: After the first iv dose of caplacizumab, platelet counts increased within 6 hours in 11 patients, and organ dysfunction improved. In these patients, platelet counts remained in the normal range during caplacizumab, no exacerbations or relapses occurred. Organ dysfunction resolved completely within a few days.
In 3 patients, platelet counts did not improve after the first dose of caplacizumab, and additional TPE was started. One patient had acute cytomegalovirus viremia, one patient had both human immunodeficiency virus and hepatitis B viremia, and one patient had immune thrombocytopenia. Up to 3 TPE sessions were necessary until platelet counts normalized.

Conclusion(s): In conclusion, the management of TTP is feasible without an absolute need for TPE. With caplacizumab and immunosuppression, complete clinical and ADAMTS13 remissions can be achieved. In patients without immediate response, additional conditions may be responsible. We suggest the initiation of a clinical trial to clarify whether TPE is still needed for TTP in the era of caplacizumab.