[Successful combination therapy with fostamatinib and romiplostim in refractory immune thrombocytopenia 27 years after onset].

The patient was a 37-year-old woman with immune thrombocytopenia (ITP) diagnosed at age 9. Steroids and splenectomy were ineffective, but high dose intravenous immunoglobulin therapy (IVIG) resulted in a transient increase in platelets. Platelet counts remained at 10,000 and 30,000/µl, so eltrombopag was started; however, the platelet count remained the same. In July 2023 (age 35 years), fostamatinib was started in combination with prednisolone 4 mg/day and eltrombopag 50 mg/day. In the first week, the platelet count rose to 126,000/µl, but then decreased; by the eighth week, it had fallen to 8,000/µl. When eltrombopag was changed to romiplostim, the platelet count generally exceeded 50,000/µl. Discontinuation of fostamatinib was attempted, but the platelet count fell to 29,000/µl. Upon resumption of fostamatinib, the platelet count stabilized again. In post-splenectomy chronic ITP patients with a long history of disease, responsiveness to IVIG indicates a high likelihood of response to fostamatinib, which has the same mechanism of action via Fc receptor inhibition. Combining fostamatinib with romiplostim, which promotes platelet production, may be beneficial due to their complementary mechanisms of action.