Directing doctor Second Affiliated Hospital of Guangzhou Medical University GUANGZHOU, Guangdong, China (People's Republic)
Background: Up to date, refractory immune thrombocytopenia (ITP) was stilled defined as low platelet count requiring treatment after splenectomy. Patient with it still has unmet requirement. Bruton’s tyrosine inhibitor (BTKi) Rilzabrutinib has been reported to be effective in chronic or persistent ITP. But the efficacy of other kind of BTKi in refractory ITP has not been reported.
Aims: To report a case with refractory primary immune thrombocytopenia who had achieved sustained complete remission after treatment with small dose of the Bruton’s tyrosine inhibitor Zanubrutinib.
Methods: A 64-year-old male was found to have progressive thrombocytopenia after been successfully treated for autoimmune hemolysis with corticosteroid. The bone marrow examination conformed to ITP. Autoimmune antibody panel was positive for SSA. MAIPA test results show that he had autoantibody against platelet membrane glycoprotein IIbIIIa and Ib/IX. Although eltrombopaq and corticosteroid were given, his platelet count still drop to 8×109/L. During the following year, he had tried low dose of decitabine, rituximab, cyclosporine A and Oseltamivir without effect. Two years later, he received splenectomy after which his platelet count increased to normal for less than 2 weeks and dropped again. He had to be treated with 40mg/d of Avatrombopag, corticosteroid, cyclosporine A together with constant injection of recombinant human thrombopoietin to maintain platelet count over 30×109/L which could drop to less than 10×109/L several times after common cold. 9 months ago, he was treated with Zanubrutinib of 80mg per day.
Results: His platelet count increased after around 10 days. Since then, the corticosteroid was tapered. Now he was treated with 80mg/d of Zanubrutinib and very low dose of cyclosporin and 20mg of Avatrombopag. His platelet count has been normal for more than 9 months without side effect.
Conclusion(s): Low dose of Zanubrutinib can be effective in patients with refractory ITP even after multi-line therapy.
