TPO and autoimmune thrombocytopenic purpura: Currently, among the five TPO receptor agonists for the treatment of ITP that have been marketed worldwide, romiplostim, the only peptide TPO-RA, has a peptide domain that binds to the TPO receptor and stimulates platelet production, and the carrier antibody Fc domain can prolong the circulation half-life.[1,14,22] Romiplostim (Nplate®), a long-acting TPO-RA requiring once-weekly dosing, was approved in China in January 2022.