Evaluation of Treatment Outcomes after Second-Line Treatment Among Adult Patients with Immune Thrombocytopenia

Introduction: Immune Thrombocytopenia (ITP) is a disease of immune-mediated destruction of platelets and suppression of platelet production. ITP has been historically treated with corticosteroids and/or immune globulins as first-line agents. There are several second-line treatments available, should patients fail to respond to initial therapy or relapse after it is tapered. These include eltrombopag, romiplostim, rituximab and splenectomy. This study utilized a national electronic health record (EHR) database to begin to explore the real world treatment patterns of the aforementioned second-line (index) therapies.

Methods: Utilizing the Optum EHR database, we identified patients who initiated their first second-line treatment (i.e. the index treatment) with eltrombopag, romiplostim, rituximab or splenectomy from Jan. 1, 2009 to Sep. 30, 2016 for primary or unspecified ITP. Patients included in the analysis had the following characteristics: 18 years or older; previous treatment with corticosteroids and/or immune globulin products; active in the database for at least 6 months prior to and 12 months post initiation of the index treatment. Outcomes that were evaluated after initiation of the index treatment included: (1) Duration of therapy for eltrombopag and romiplostim; (2) Proportion of patients who started a subsequent line of treatment after their index treatment; (3) Treatment free duration between the end of the index treatment and start of a subsequent line of treatment; and (4) Proportion of patients using a first-line medication (corticosteroids and/or immune globulin) during treatment with eltrombopag and romiplostim. Chi-square and t-tests were used for statistical analysis.

Results: 2,047 patients met the inclusion criteria and used an index treatment as follows: eltrombopag, N=110 (5.4%); romiplostim, N=189 (9.2%); rituximab, N=1488 (72.7%); splenectomy, N=260 (12.7%). The mean age was 60.8 years (standard deviation [SD]: 17.4), with 52.4% female and mean Charlson comorbidity score of 2.1 (SD: 2.1). Treatment duration was 481 days for eltrombopag versus 346 days for romiplostim (p=0.033). The proportion of patients who started a subsequent line of treatment after their index treatment ranged from 41% for rituximab to 49% for splenectomy (p=0.071). Treatment free duration between the end of the index treatment and start of a subsequent treatment ranged from a mean of 248 days for romiplostim to 575 days for splenectomy (p<0.001). The proportion of patients who did not use first-line medications during treatment with eltrombopag and romiplostim were similar (24% vs. 17%, p=0.157). See Table 1 below for details.

Conclusions: In this dataset, rituximab was the predominant second-line treatment. Patients receiving eltrombopag had a greater treatment duration compared to romiplostim. As expected, a greater treatment free duration was observed with splenectomy and rituximab, though mean treatment free duration after treatment with romiplostim and eltrombopag was surprisingly long (248-270 days). Despite the longer duration off treatment following splenectomy and rituximab, a similar percentage of patients across all index treatments ultimately required a subsequent line of therapy. Further research is required to better understand the differences in real world treatment patterns among these cohorts.

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