Promising results from cyclophosphamide based immunosuppression therapy of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura is a rare disease. Therefore, the small numbers of patients in trials results in statistically weak evidence supporting treatment guidelines. The aetiology of this disease is based on a deficiency of metalloproteinase 13 (ADAMTS-13), which leads to the creation of von Willebrand factor polymers and platelet microthrombosis in small vessels. Treatment relies on plasma exchange. Immunosuppression based on cyclophosphamide is not recommended in current guidelines. The aim of this study was to assess the early and long-term effects of treatment, and to evaluate therapy prognostic factors.

This was a retrospective study of 10 patients hospitalized 14 times due to new or recurrent onset of TTP. Currently recommended treatment was used in all cases, including total plasma exchange (range 0.5-2 plasma volume). The volume of exchange plasma was 24.6 L (mean) over 20 days (median). All patients received glucocorticosteroids. Immuno-uppression (based on cyclophosphamide in 7 cases) was utilized in 70% of patients (9 patients).

Of all 11 patients 9 (70%) survived and achieved remission. Fifty percent of patients stayed in long-lasting remission. Average follow-up time was 36 months (median 14.5 months, range 10 days to 108 months). Factors improving the chance of remission were: age below 55 years (p < 0.05), no tachycardia on admission to hospital (p < 0.001), and immunosuppression based on cyclophosphamide (p = 0.032).

Presence of tachycardia on TTP onset and age above 55 years reduce the survival and remission rate. Remission from TTP is suggested to be caused by immunosuppression based on cyclophosphamide.