Abstract
Introduction
Immune thrombocytopenia (ITP) is an acquired disorder characterized by immune-mediated platelet destruction along with decreased platelet production. Adults with ITP are treated initially with glucocorticoids, intravenous immunoglobulin, and/or anti-D, but as many as 80% of patients (pts) will eventually relapse and become steroid-refractory. There is no universally agreed upon 2nd line therapy for ITP and consensus guidelines recommend either rituximab (R) or splenectomy (S) as acceptable, potentially curative options. Long-term responses to 2nd line S have been reported around 60%, and around 25% for R. It is unknown whether long-term outcome in the 3rd line setting is influenced by sequence of therapy. We evaluated the impact of sequence of 2nd and 3rdline therapy with R and/or S.
Methods
We identified all pts with ITP treated from 1990 through 2015 at the three Mayo Clinic (Arizona, Florida, and Minnesota) sites that were treated with R and/or S. Patients were excluded who were <18 years of age at the time of second-line treatment. Those with secondary ITP that received specific treatment for an infectious, autoimmune, or malignant condition causing thrombocytopenia were excluded. Patients with Evan's syndrome were included if the treatment was for thrombocytopenia, and not primarily for hemolytic anemia. For this analysis, secondary ITP was defined as ITP associated with hematologic malignancy. Hematologic malignancies did not require specific therapy at the time of treatment for ITP. Patients with uncontrolled infections or uncontrolled autoimmune disorders were excluded from analysis. We collected data from medical records regarding demographics, medical history, treatment history, response to treatment, and relapse. Medical history was captured for all concurrent diagnoses that could be considered associated with ITP including infectious and autoimmune conditions. Primary end-points were freedom from relapse after 2nd and 3rd line treatment with R or S. We used Kaplan-Meier method to estimate freedom from relapse after 2nd and 3rd line treatments. We also evaluated response to treatment, as defined by a platelet count >30,000/mm3 according to consensus guidelines. We performed three separate analyses for the entire cohort, primary ITP, and secondary ITP (separating out those with a concurrent diagnosis of malignancy).
Results
We identified 222 patients with a diagnosis of ITP, of which 191 had primary and 31 had secondary ITP. Treatment characteristics were similar in all groups except that pts treated initially with S were younger at diagnosis than pts treated with R (49 vs 60 years, P=0.003) and at time of 2ndline treatment (51.5 vs 61 years, P=0.018). For the overall cohort, patients treated with S as second-line therapy were more likely to achieve CR (86.6% vs 44%, P<0.0001), and had a significantly higher freedom from relapse at 5y (53.57% v. 14.96%, P<0.0001). Patients treated with S followed by R (S to R) had a trend towards higher 2y freedom from relapse than those treated with R followed by S (R to S) (69.48% v. 58.43%, P=0.3264). These data remained similar when primary ITP and secondary ITP were separated (data not shown).
Conclusions
These data support that S provides superior FFR at 5 years compared to R as second line treatment and suggests that, when needed, splenectomy followed by rituximab as opposed to rituximab followed by splenectomy might have a slight advantage.
No relevant conflicts of interest to declare.
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