Initiation of a prospective observational cohort study of patients with acquired thrombotic thrombocytopenic purpura (TTP)

T. Falter1, A. Trinchero1, K. Jurk1, H. Roßmann1, K. Lackner1, B. Lämmle1,2, C. von Auer1 (1Mainz, Germany, 2Bern, Switzerland)

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

Objective: Acquired TTP is an acute life-threatening thrombotic microangiopathy most often caused by autoantibody-mediated severe ADAMTS13 deficiency. The annual incidence is 2-4 cases/1 million and despite intensive daily plasma exchange therapy (PEX) and corticosteroid treatment the mortality is still 10-20%. Survivors have a 40-50% risk of relapse during the ensuing 5-10 years and may be affected by neurocognitive problems, arterial hypertension and increased mortality. Our cohort study aims to answer whether acute relapses in survivors of an acute TTP can be predicted based on clinical and/or laboratory parameters assessed during regular outpatient follow-up visits.

Methods: A protocol for all consecutive patients with acute acquired TTP hospitalized at UMC Mainz as well as for survivors of acute TTP referred to the outpatient ward for regular follow-up visits every 3 months has been established and approved by the responsible Ethics Committee of Rhineland Palatine. Clinical and laboratory parameters are assessed daily during the acute disease and at each follow-up visit. In addition, biobanking of whole blood, citrated and EDTA plasma and serum samples is performed. Besides planned Next Generation Sequencing (NGS) of ADAMTS13, von Willebrand factor, complement and complement regulatory genes, stored biomaterial will be available for new assays to be developed. Biodatabanking is supported by an electronic database established for this cohort.

Results: The first patient, in remission after surviving acute TTP, was enrolled in July 2016 and by 10th October 2016, a total of 31 patients seen in the outpatient ward in clinical remission and one patient admitted for PEX therapy for acute TTP have been enrolled. One outpatient with earlier recurrent acquired TTP was treated with rituximab because of progressive decrease of ADAMTS13 activity and increasing inhibitor titers according to treating physician´s judgement.

Conclusion: This inception cohort study on acquired TTP patients has been successfully started as a single-center study and it is planned to invite other centers to participate. Besides learning more on the natural disease course, we hope to develop new diagnostic and/or prognostic parameters.