A Case Series and Literature Review on Zanubrutinib Therapy for the Treatment of Relapsed/Refractory Immune Thrombocytopenia.

Background: Immune thrombocytopenia (ITP) is an acquired autoimmune disease characterised by low platelet count. Treatment discontinuation or heterogeneity in the pathogenesis of ITP heightens the occurrence of relapsed or refractory ITP. Bruton's tyrosine kinase (BTK) has emerged as a promising target for autoimmune disorders.

Methods: In this case series, we have explored the efficacy and safety of Bruton's tyrosine kinase inhibitors (BTKi) in treating relapsed/refractory ITP, by retrospective analysis of the diagnostic history and efficacy of four patients with relapsed/refractory ITP who attended the Affiliated Cancer Hospital of Zhengzhou University and were treated with BTKi. All four patients received > 4 lines of ITP treatment and did not respond to splenectomy or other interventions before and after treatment with BTK inhibitor. After adjusting to the treatment with BTKi, one patient achieved a complete response, and two patients achieved a partial response. All three patients achieved sustained remission with platelet counts of > 50 × 109/L maintained for 1045, 390 and 334 days, respectively. Another patient died of intracranial haemorrhage due to a decline in the platelet count after discontinuation of the drug, and the duration of sustained remission before discontinuation of the drug was 120 days. Four patients had no significant abnormalities in the functions of the liver and kidney monitored during the treatment period.

Conclusions: For patients with relapsed/refractory ITP, BTK inhibitor therapy can be considered as an option, with promising preliminary efficacy and safety. However, more clinical trials are needed to verify the exact data.