Abstract
Background: Immune thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening disorder managed with plasma exchange (PLEX) and steroids. Addition of rituximab (RTX) to initial disease treatment has been shown to lower future relapse rates. Information as to whether upfront cyclophosphamide (CTX) treatment is helpful in reducing relapse is not known.Methods: In a retrospective cohort study, we identified all patients at our institution diagnosed with iTTP between 2010 and 2019. We analyzed outcomes of cumulative incidence of relapse (CIR) and duration of remission.Results: Thirty Nine patients were studied. Group A (n = 10) included patients who received upfront PLEX and steroids alone, and Group B (n = 28) included those who received either upfront RTX (n = 23) or CTX (n = 5) in addition to PLEX and steroids. The 2-year CIR was 50% in Group A and 27.7% in Group B, with a median duration of remission of 43.6 months vs. 108.3 months, respectively (p = 0.04). Group A was associated with a HR=8.7 (95% CI: 1.27, 59.45), p = 0.027 for duration of remission. There was no significant difference between CTX and RTX in both outcomes of CIR and duration of remission. We observed a potential impact on remission duration based on the presenting absolute neutrophil count (HR = 0.74, 95% CI: 0.58, 0.96) and serum creatinine (HR = 1.42, 95% CI: 1.03, 1.94).Conclusion: There was no significant difference in iTTP relapse outcomes between upfront RTX and CTX. Absolute neutrophil count and serum creatinine may have a role in predicting relapse. Larger, prospective studies are needed to evaluate these findings.
Highlights
Auto-immune thrombotic thrombocytopenic purpura is a rare, life-threatening disorder caused by auto-antibodies against ADAMTS13
Our study results demonstrate that the upfront use of immunosuppressive therapy, in addition to steroids and plasma exchange (PLEX) is associated with a reduction in the cumulative incidence of relapse and prolongs the duration of remission
Low-dose pulse intravenous CTX used for immune thrombotic thrombocytopenic purpura (iTTP) is associated with far less adverse effects compared to higher doses of CTX, which can lead to infectious complications, bone marrow suppression, and long-term risk for malignancy [24]
Summary
Auto-immune thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening disorder caused by auto-antibodies against ADAMTS13. Rituximab (RTX) is a monoclonal antibody that targets B-cells, which produce the antibody responsible for causing iTTP It was first used in treating this disease in the relapsed or refractory setting in the early 2000s, and was successful in inducing remission [10, 11]. The Phase II trials by Scully et al and Chen et al demonstrated safety and efficacy of using upfront RTX [8, 12] In the former trial, RTX was associated with 10% relapse rate compared to 57% in historical controls, which was a statistically significant reduction [8]. Information as to whether upfront cyclophosphamide (CTX) treatment is helpful in reducing relapse is not known
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