Prophylactic plasma treatment in patients with hereditary thrombotic thrombocytopenic purpura

Z. Cermakova1, P. Kovarova1, J. A. Kremer Hovinga2 (1Ostrava, Czech Republic, 2Bern, Switzerland)

Platelets - Physiology and Disorders of platelet number and function
Date: 17.02.2017,
Time: 17:15 - 18:15

Objective: Hereditary TTP is a very rare autosomal recessive disease due to mutations in ADAMTS13 gene resulting in severe deficiency of ADAMTS13, a metalloprotease that cleaves ultra-large von Willebrand factor multimers. There are 7 patients with USS followed and treated at the Blood Centre at the University Hospital in Ostrava who require prophylactic fresh frozen plasma (FFP), and/or solvent detergent plasma (SDP) in empirically determined treatment schedules. ADAMTS13 recovery and pharmacokinetics are affected by treatment modality and reflect associated patient comorbidities as well as their current clinical condition. The aim of this study was to estimate ADAMTS13 recovery upon regular plasma infusion (PI) or plasma exchange ( PEX) regimens.

Methods: Six of 7 USS patients, who regularly received prophylactic FFP/SDP therapy between June 2013 and March 2015 took part in this study. During this period FFP was replaced by SDP treatment. ADAMTS13 activity was assessed in patient samples as well as in all individual FFP and SDP bags by two methods – an enzyme-linked immunosorbent assay and FRETS-VWF73 assay.

Results: There was excellent agreement between both ADAMTS13 assays in all samples analyzed and there was no statistically significant difference in ADAMTS13 activity levels between FFP and SDP preparations . All patients had baseline ADAMTS13 activity < 5% and none had a functional inhibitor or anti-ADAMTS13 antibody at any time during this study. ADAMTS13 recovery in patients after PEX was 54.5±10.6% (mean ± SD) and 25.4±5.2 % after PI.

Conclusion: Usually PI is recommended for prophylactic plasma therapy in USS patients. Based on our experience in patients with a more severe disease course, however, we prefer PEX via peripheral venous access. Thereby, more plasma and thus ADAMTS13 can be administered at a single treatment cycle. In addition the patients benefit from less volume overload and from elimination of degradation products.