ADAMTS13 Activity Levels Predict iTTP Recurrence

A study presented at the International Society on Thrombosis and Haemostasis (ISTH) 2020 Virtual Congress confirms the value of longitudinal quarterly assessment of ADAMTS13 activity for predicting recurrence of immune-mediated thrombotic thrombocytopenic purpura (iTTP).

Steep declines in ADAMTS13 activity identified patients at risk for disease relapse or exacerbation, said lead study author Charis von Auer-Wegener, MD, from the Center for Thrombosis and Hemostasis at the University Hospital Mainz in Germany.

“Severe deficiency of ADAMTS13 activity resulting from autoantibodies is the primary cause of iTTP,” Dr. von Auer-Wegener explained. While approximately 30% of patients will experience disease exacerbation or relapse, there are no reliable biomarkers that predict disease recurrence, she added.

With this study, Dr. von Auer-Wegener and colleagues investigated the role of ADAMTS13 activity as a biomarker of iTTP relapse or exacerbation in 103 patients with iTTP. Participants were followed for a median of 1,041 days and ADAMTS13 activity was assessed every 3 months.

During this time, 13 patients had a disease relapse. Of the 85 patients with at least two follow-up visits to measure ADAMTS13 activity, 44 (52%) had continuously normal ADAMTS13 activity (≥50%). None of these patients had a disease relapse, the authors reported.

In addition, for the 2 patients with ADAMTS13 activity continuously between 25-50% and 1 patient with ADAMTS13 activity continuously between 10-25%, there were no iTTP relapses.

However, for the 9 patients who had ADAMTS13 activity continuously <10%, 8 had a disease relapse.

Trends in ADAMTS13 activity also were predictive of relapse. None of the 30 patients with undulating parameters of ADAMTS13 activity experienced an exacerbation or relapse, compared with half of the 10 patients with a steep decline of ADAMTS13 activity.

The investigators concluded that a reduction by at least a factor of 2 within 3 months (defined as values ≥50% to <50%) showed a strong association with occurrence of relapse (hazard ratio = 11.26; 95% CI 3.66-34.62; p<0.0001). They added that baseline ADAMTS13 activity, age, and sex were not indicators of relapse risk.

“These results suggest the need for additional off-label therapeutic coverage (rituximab, corticosteroids, caplacizumab) to prevent recurrence in the long-term management of patients with iTTP,” the authors concluded. The study’s findings are limited by the small sample size.

The authors report no relevant conflicts of interest.


von Auer-Wegener C, Schmidtmann I, Bach L, et al. Longitudinal assessment of ADAMTS13-activity helps predict recurrence of immune thrombotic thrombocytopenic purpura (iTTP): results from the German TTP-registry. Abstract OC 07.4. Presented at ISTH 2020 Virtual Congress; July 12-14, 2020.