Anti-GPIb/IX autoantibodies are associated with poor response to dexamethasone combined with rituximab therapy in primary immune thrombocytopenia patients.

This retrospective study aimed to evaluate whether anti-glycoproteins (GPs) autoantibodies can be used as predictors of response to high-dose dexamethasone combined with rituximab (DXM-RTX) in the treatment of primary immune thrombocytopenia (ITP) patients. One-hundred twenty-six ITP patients were included and retrospectively analyzed, 66.7% of anti-GPIb/IX and 65.9% of anti-GPIIb/IIIa autoantibodies. Results showed that overall response (OR) and complete response (CR) rates of patients without anti-GPIb/IX autoantibodies to DXM-RTX were significantly higher than those with anti-GPIb/IX autoantibodies at 4 weeks (OR: 73.8% vs. 47.6%, CR: 50.0% vs. 26.2%; P < 0.05) and 6 months (OR: 71.4% vs. 45.2%, CR: 42.9% vs. 25.0%; P < .05). Furthermore, patients with anti-GPIb/IX single-positivity exhibited higher resistance to DXM-RTX than patients with anti-GPIIb/IIIa single-positivity at 4 weeks (OR: 37.5% vs. 78.3%; P < .05) and 6 months (OR: 29.2% vs. 78.3%; P < .05). Multivariable logistic regression analysis revealed that anti-GPIb/IX autoantibodies and megakaryocytes were associated with the OR rate of patients at both 4 weeks and 6 months, and anti-GPIb/IX autoantibodies at 4 weeks represented the only significant factor affecting OR rate with DXM-RTX (F = 9.128, P  = .003). Therefore, platelet anti-GPIb/IX autoantibodies might predict poor response to DXM-RTX in ITP patients.