OBJECTIVES: Chronic immune thrombocytopenia purpura (ITP) is an acquired autoimmune disease characterized by antibody-induced platelet (PLT) destruction, leading to a reduction in the number of circulating PLTs. Initial treatment is with corticosteroids. In patients who become resistant to corticosteroids, the TPOs, consisting of romiplostim (ROM), eltrombopag (ELT) and avatrombopag (AVA) or the spleen tyrosine kinase inhibitor fostamatinib (FOS), are appropriate next lines of therapy. In this study, the comparative safety and effectiveness between fostamatinib vs. the TPOs was evaluated in a real-world setting.

METHODS: The medical records of patients treated in one of 17 community hematology practices across the U.S. were reviewed. Data collection consisted of patient demographics, disease characteristics, as well as number and type of prior treatments. From the first day until the end of treatment, data were also collected on PLT counts, adverse events, the use of rescue IVIG, PLT transfusions and rescue corticosteroids. Multivariable logistic regression analysis adjusted for clustering was used to compare PLT related endpoints between agents.

RESULTS: A sample of 179 ITP patients who had received at least one of the four agents was identified. This resulted in a final sample of 51, 87, 127 and 44 patients who received FOS, ELT, ROM or AVA respectively. At month three and six, there were no significant differences between FOS vs. the TPOs in the proportion of patients with the PLT count being ≥ 30 x 10³/μL, ≥ 50 x 10³/μL, as well as the proportion whose PLTs levels doubled relative to baseline. Thromboembolic events (TEs) occurred in 3.9% of FOS patients compared to 9.2%, 4.7% and 11.4% in the ELT, ROM and AVA groups respectively.

CONCLUSIONS: FOS was comparable to the TPOs in maintaining PLTs at clinically beneficial levels. Therefore, treatment selection should be based on patient safety, preexisting risk factors for TEs and cost effectiveness.