Exploring the Immune-related Biomarkers for Predicting the Efficacy of Rituximab Treatment in Patients with Chronic Immune Thrombocytopenia

X. Wang^1,2,3, H. Li^1,2,3, X. Liu¹, F. Xue¹, W. Liu¹, Y. Chen¹, R. Fu¹, L. Zhang^1,2,3, R. Yang^1,2,3

¹State Key Laboratory of Experimental Hematology, National Clinical Research Center for Hematological Disorders, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China, ²CAMS Key Laboratory of Gene Therapy for Blood Diseases, Tianjin, China, ³Tianjin Laboratory of Blood Disease Gene Therapy, Tianjin, China

Abstract Number: PB0816

Meeting: ISTH 2021 Congress

Theme: Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies » Acquired Thrombocytopenias

Background: Immune thrombocytopenia (ITP) is an autoimmune disease caused by immune intolerance. Rituximab is a monoclonal antibody for therapeutic B-cell depletion, which has been used as second-line therapy in chronic ITP with up to 60% response rates. However, considering its high cost and complications, it is necessary to find biomarkers to predict clinical efficacy to help clinicians make better choices.

Aims: To explore the immune-related biomarkers for predicting response to rituximab in patients with chronic ITP.

Methods: We prospectively included 30 patients with chronic ITP in our center from May 2019 to Nov 2020. We examined the phenotypes of peripheral blood lymphocytes, monocytes, and T helper (Th) cells in 4 hours cultured peripheral blood mononuclear cells in vitro stimulated by PMA/ ionomycin. Efficacy was evaluated 3 months after rituximab treatment. Optimal cutoff values were established using ROC analysis.

Results: Among 30 patients, there were 9 males and 21 females, with a median age of 30 (11-57) years. Eighteen patients showed response (PLT≥30×10⁹/L after treatment). Comparing immune status before rituximab therapy, naïve B cells /CD19+B lymphocyte(Bn/B) in the effective group was significantly higher than that in the ineffective group [(68.9±9.8)% vs (57.6±11.6)%, P=0.024]. Memory B cells/CD19+B lymphocyte(Bm/B) had a lower level in the effective group compared with the ineffective group [(29.5±9.9)% vs (41.7±11.5)%, P=0.014]. Significantly difference was observed in the ratio of Th1/Th2 between the effective and the ineffective group [(8.0±4.1)% vs (13.3±5.2)%, P=0.012]. Patients were divided further using an optimal cut-off Bn/B of 62.7%, Bm/B of 37.0% and Th1/Th2 of 9.8. The model had an AUC of 0.910 (95% CI 0.778-1.000).

ROC curve for predicting the efficacy of rituximab

Conclusions: ITP patients with Bn/B>62.7%,Bm/B<37.0% and Th1/Th2<9.8 tend to achieve response by rituximab treatment. Our study proposed a model for predicting the efficacy of rituximab, which is helpful to assist clinicians in making treatment decisions.

To cite this abstract in AMA style:

Wang X, Li H, Liu X, Xue F, Liu W, Chen Y, Fu R, Zhang L, Yang R. Exploring the Immune-related Biomarkers for Predicting the Efficacy of Rituximab Treatment in Patients with Chronic Immune Thrombocytopenia [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/exploring-the-immune-related-biomarkers-for-predicting-the-efficacy-of-rituximab-treatment-in-patients-with-chronic-immune-thrombocytopenia/. Accessed November 30, 2023.

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