Real-world Experience of Caplacizumab for Adolescents in the First-line Setting: Case Reports.

Acquired thrombotic thrombocytopenic purpura (aTTP) is a thrombotic microangiopathy resulting in high mortality. Caplacizumab is approved for treatment of adults with acquired thrombotic thrombocytopenic purpura that has shown faster platelet normalization, clinical improvement, and reduced risk of recurrent/refractory disease. We report 2 cases of adolescents treated off-label with caplacizumab who were able to stop before 30 days from end of plasma exchange after platelets normalized and ADAMTS13 activity recovered to >20% to 30%. Our results show similar efficacy to other reports of patients under 18 receiving caplacizumab in first line, regardless of plasma exchange strategy, and may offer insight into early cessation criteria.