ADAMTS13 kinetics after therapeutic plasma exchange and plasma infusion in patients with Upshaw-Schulman syndrome

BACKGROUND: Hereditary thrombotic thrombocytopenic purpura, also called Upshaw-Schulman syndrome (USS), is a rare disease caused by genetic mutations in the ADAMTS13 gene, which severely decrease the activity of ADAMTS13, a metalloprotease that cleaves von Willebrand factor multimers (VWF). Genotypically identical patients can show great phenotypic diversity. OBJECTIVES: Comparison of selected laboratory parameters and ADAMTS13 pharmacokinetics among patients with USS was performed. PATIENTS/METHODS: Six patients with USS on prophylactic plasma therapy have been reviewed, retrospectively. Blood counts, lactate dehydrogenase (LDH), and ADAMTS13 activity at various time-points before and after different treatment cycles were evaluated. RESULTS: ADAMTS13 recovery and pharmacokinetics were affected by treatment modality, and also reflected the patients' comorbidities and their current physiological and clinical condition. CONCLUSIONS: Our present findings support a multifactorial contribution to treatment efficacy, and confirm the importance of adaptability and individualization of USS therapy. Therapeutic plasma exchange even in hereditary TTP is an option that can in some patients prolong intervals between plasma administration.