TGFβ1 and sCTLA-4 levels are increased in eltrombopag-exposed patients with ITP

Some thrombopoietin receptor-agonists (TPR-As) have been developed and shown to be highly effective in the treatment of immune thrombocytopenic purpura (ITP). Soluble cytotoxic T-lymphocyte-associated antigen 4 (sCTLA-4) can modulate and terminate the immune response. Several reports have shown that sCTLA-4 levels are elevated in patients with some autoimmune disorders. However, sCTLA-4 levels have not previously been investigated in TPR-A exposed patients with ITP. We investigated the levels of transforming growth factor (TGF) β1 and sCTLA-4 in ITP patients to determine the clinical association with TGFβ1 and sCTLA-4 in TPR-A-exposed patients with ITP. Thirty-seven ITP patients were divided into 2 groups (TPR-A-exposed: 13 patients; unexposed: 24 patients). Doses of eltrombopag ranging from 12.5 mg to 50 mg were administered daily, and biochemical data obtained before and after eltrombopag administration were compared. Eltrombopag therapy significantly increased sCTLA-4 and TGFβ1 levels relative to baseline in patients with ITP. In addition, plasma TGFβ1 was positively correlated with platelet counts and sCTLA-4 in patients with ITP in the eltrombopag-exposed group. However, no significant change in the detection rate for anti-glycoprotein antibody was observed before and 24 weeks after eltrombopag treatment. These results suggest that eltrombopag can partially modulate some immune responses by TGFβ1 and sCTLA-4, but it does not induce immune tolerance by 24 weeks after treatment.