Response To Lower Dose Rituximab Therapy In Childhood And Adult With Relapsed Or Refractory Immune Thrombocytopenia

OBJECTIVE Immune thrombocytopenia(ITP) is the most common autoimmune haematological disorders,including primary and secondary ITP, such as systemic lupus erythematosus-associated, pSS-associated or EVANS associated-ITP. Primary immune thrombocytopenia are characterized by the production of antibodies against self antigens GPⅡb/IIIa,GP I b/IX, known as autoantibodies. Current treatment regimens for ITP tend to be relatively non-selective in their mechanism of action(e.g. corticosteroids and cytotoxic drugs). Consequently, treatments are not always of long duration and may be associated with significant systemic toxicity. Recently, it has become clear that B cells play a key role in both the development and perpetuation of autoimmunity, suggesting that B-cell depletion could be a valuable treatment approach for patients with autoimmune diseases. The pathogenic roles of B cells in ITP involve production of autoantibodies,antigen presentation,chemokine secretion. Rituximab is a chimeric monoclonal antibody that specifically depletes B cells from the blood, lymph nodes and bone marrow by targeting CD20. Most studies using rituximab in ITP employed the same dose as is used to treat lymphoma (375mg/m2 weekly for 4 weeks),the regimen is expensive, lower doses of rituximab include four once-weekly doses of 100 mg rituximab and a single dose (375mg/m2). This therapy is cost-effective. In this context, the B-cell total mass is much less than in patients with lymphoma.Therefore,a reduced dosage of rituximab might still be sufficient for its therapeutic purpose.Based on this assumption,we performed a prospective,single center non-randomized control study of lower dose rituximab in childrenhood and adult with relapsed or refractory immune thrombocytopenia. This paper examines the evidence supporting the use of lower doses of rituximab in the treatment of ITP(primary and secondary ITP) and correlated results with clinical and laboratory findings.Methods We treated 46 patients with ITP using rituximab at 100mg per week, IV, for four weeks and 25 patients with ITP using rituximab at single dose 375mg/m2,including 63 primay ITP and 8 secondary ITP.These patients were unresponsive to (or relapse after) steroids and/or IVIG treatment and/or splenectomy. The evaluation of the response was made monitoring the platelet count every week during the fiest month of treatment,then at bi-weekly intervals up to the sixth month and then monthly.Serum concentrations of IgG, IgM, IgA, Platelet associated (PA)-IgG, PAIgA and PAIgM, CD19+/CD20+,CD3+T,CD3+CD4+T,CD3+CD8+T,CD3-CD56+T cells were been detected at baseline and thenl,3,6,9month from the beginning of rituximab treatment.Results 1 Response in the adult patients with ITP:①Once-weekly doses of 100 mg rituximab group:28 patients with primary and 4 patients with secondary ITP. Complete response (CR) was achieved in 8 patients (25%), R in 14 (44%). The median time to response and complete response were 40 days and 66 days respectively. The median time to follow-up time is 341 (52～447)days. Overall response was achieved in 22/32(69%).3/32 patients relapsed and 3 needed further treatments.②Single dose (375 mg/m2) group:18 patients with primary and 3 patients with secondary ITP. CR was achieved in 5 patients (24%), R in 5(24%). The median time to R and CR were 35 days and 19 days respectively.The median time to follow-up time is 145(5～335)days. Overall response was achieved in 10/21(48%).1/21 patients relapsed and needed further treatments.2 Response in the children patients with ITP:①once-weekly doses of 100 mg rituximab group:14 patients with primary. CR was achieved in 2 patients (14%), R in 6 (43%). The median time to response and complete response were 74 days and 71 days respectively.The median time to follow-up time is 236(57-395)days. Overall response was achieved in 8/14(57%).4/14 patients relapsed and needed further treatments.②Single dose (375 mg/m2) group:3 patients with primary and 1 patients with secondary ITP. CR was achieved in 2 patients 50%).The median time to follow-up time is 267(21-259)days. The median time to CR were 104 days. Overall response was achieved in 2/4(50%).3 RFS probabilities were no different in two group. No pretreatment laboratory parameters predicting response and relapse have been identified. The serum concentrations of IgG, IgA, IgM, CD3+,CD3+CD4+,CD3+CD8+and CD3"CD56+T cells were not changed between before and after therpy. The number of CD19+CD20+cells significantly decreased after treatment. PAIgG was lower after treatment compared with before treatment.4 There were no severe adverse events during rituximab therapy. Five patients were re-treated,including 1 in relapse,2 maintain therapy and 1 salvage therapy.Conclusion Treatment with lower dose rituximab may be an effective and safe approach in patient with ITP, which fail to respond to conventional therapies. Rituximab should be considered a presplenectory therapeutic approach.However, the optimal therapeutic schedule,long-term efficacy, adverse events need to further investigation. Background:Immune thrombocytopenia(ITP) is an organ-specific autoimmune disorder characterized by accelerated platelet destruction. The pathophysiology of ITP remains unclear completely. Recently, it has become clear that T and B lymphocyte cells play a key role in both the development and perpetuation of autoimmunity, suggesting that B-cell depletion could be a valuable treatment approach for patients with autoimmune diseases.However,its mechanisms of action as well as the effects on T and B lymphocyte remain poorly defined. B cell activating factor belonging to the TNF family (BAFF) plays an important role in peripheral B cell survival and homeostasis and T cell activation. To determine the roles of BAFF and regulation T cell in the pathogenesis of ITP post rituximab-based B cell depletion therapy, the expression of BAFF and and regulation T cell in patients with ITP were detectedObjective:To determine the expression of regulatory T cells,BAFF in ITP patients after B-cell-depleting therapy with rituximab, and make a preliminary study of the pathogenic roles of these factors in ITP.Methods:We treated 28 patients with ITP using rituximab at 100mg per week, IV, for four weeks and 8 patients with ITP using rituximab at single dose 375mg/m2. We chose baseline before therapy, at 1 month (since first rituximab infusion), at 3-6momth(since first rituximab infusion), at 7-11 months (since first rituximab infusion) as the main evaluation point.The expression of CD3+,CD3+CD4+,CD3+CD8+,CD3"CD56+,CD4+CD25+,CD4+CD25+FOXP3", CD4+CD25+FOXP3+and CD19+/CD20+were analysed by flow cytometry (FACS) before and after rituximab therapyThe serum levels of BAFF were determined with ELISA and its correlation with clinical parameters were analysed before and after rituximab therapy. Meanwhile,the mRNA expression levels of BAFF in the peripheral blood mononuclear cells were measured by RT-PCR in 36 patients with ITP and 22 normal controls.Results:Serum BAFF levels were significantly higher in ITP patients than in healthy controls (p<0.01).Serum BAFF levels markedly rose after 1 month rituximab-based B cell depletion therpy (p<0.01).Serum BAFF levels were no change after 3-6 month compared to before treatment. The mRNA expression levels of BAFF in the peripheral blood mononuclear cells before rituximab therapy is higher than in healthy control(p>0.05). The mRNA expression levels of BAFF in the peripheral blood mononuclear cells markedly rose after 1 month rituximab-based B cell depletion therpy (p<0.05).Serum BAFF baseline levels did not correlate with the number of CD20,the recovery time of CD20 cell serum Ig, PAIg, patient age, sex, and disease duration of patients with ITP. The number of CD4+CD25+Foxp3- decreased after treatment. The serum concentrations of IgG, IgA, IgM, CD3+, CD3+CD4+, CD3+CD8+, CD3-CD56+, CD4+CD25+and CD4+CD25+Foxp3+T cells were not changed between before and after therpy.Conclusion:Our data demonstrate that ITP patients with unresponsive to (or relapse after) steroids and/or IVIG treatment and/or splenectomy shows higher BAFF levels than that of controls. This factor might play an important role in the pathogenesis of ITP.Serum BAFF levels and the mRNA expression levels of BAFF markedly rose post rituximab-based B cell depletion therapy with ITP. But pathogenesis need to further investigation. Frequency of regulatory T cells and T lymphocyte subset are not affected by transient B cell depletion using rituximab in ITP,but active T is affected.