Beijing InnoCare Pharma Tech Co., Ltd is conducting a phase II randomized, open, multi-center trial evaluating the efficacy of Orelabrutinib, a Bruton’s tyrosine kinase inhibitor, in adult ITP. The trial will begin with a phase IIa trial, consisting of a screening, treatment, and safety follow up period. Individuals between 18-80 years old with persistent or chronic ITP (>3 months from diagnosis) and have failed to respond to 1+ first-line ITP therapies are eligible to enrol. Individuals who had hemorrhage 4 weeks prior to screening, history of blood disorders other than ITP, cancer, organ transplantation, or have an active infection will be excluded. The selection criteria for the phase IIb trial will be released after obtaining a better understanding of the efficacy, risks, and benefits of the therapy upon completion of the phase IIa trial.