Real-world data confirm the effectiveness of caplacizumab in acquired thrombotic thrombocytopenic purpura

Abstract

Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare but life-threatening condition. In 2018, the nanobody caplacizumab was approved for the treatment of adults experiencing an acute episode of aTTP, in conjunction with plasma exchange (PEX) and immunosuppression for a minimum of 30 days after stopping daily PEX. We performed a retrospective, observational analysis on the use of caplacizumab in 60 patients from 29 medical centers in Germany during acute disease management. Caplacizumab led to a rapid normalization of the platelet count (median, 3 days; mean 3.78 days). One patient died after late treatment initiation due to aTTP-associated complications. In 2 patients with initial disease presentation and in 4 additional patients with laboratory signs of an exacerbation or relapse after the initial therapy, PEX-free treatment regimens could be established with overall favorable outcome. Caplacizumab is efficacious in the treatment of aTTP independent of timing and ancillary treatment modalities. Based on this real-world experience and published literature, we propose to administer caplacizumab immediately to all patients with an acute episode of aTTP. Treatment decisions regarding the use of PEX should be based on the severity of the clinical presentation and known risk factors. PEX might be dispensable in some patients.

Graphical abstract

Figure 1.

Violin blots depict the distribution of main treatment and outcome parameters. Red lines indicate medians; blue lines indicate 75th and 25th interpercentile quartile. ^aTotal stay includes before, during, and after caplacizumab treatment.

Figure 2.

Average platelet counts and standard error of the mean in relation to the start of caplacizumab treatment. Average platelet counts (A) and lactate dehydrogenase (B) and standard error of the mean in relation to the start of caplacizumab treatment. The x-axis (time in days) denotes the time elapsed since the start of caplacizumab and not since the initial diagnosis (ie, day 0). Please note that there is no fixed correlation between the beginning of caplacizumab and the beginning of the treatment, because caplacizumab was not used as a frontline agent in a relevant number of instances. Green dotted lines indicate upper limit of normal (ULN) or lower limit of normal (LLN).

Figure 3.

Kaplan-Meier curves of patient fractions remaining without final normalization of platelet count (>150 × 10⁹/L) after the start of caplacizumab treatment.