Low-dose rituximab therapy for refractory thrombocytopenia in patients with systemic lupus erythematosus-a prospective pilot study

Objectives: To evaluate the safety and efficacy of low-dose rituximab therapy for refractory thrombocytopenia in patients with SLE. Methods: Ten adult SLE patients with severe refractory thrombocytopenia (mean platelet count 10.4×10⁹/l) were enrolled in this prospective pilot study. All patients had failed traditional high-dose CSs and immunosuppressants including methylprednisolone pulse therapy. Patients were scheduled to receive i.v. rituximab at a dose of 100mg once weekly for 4 weeks. Previous dose of CSs were gradually tapered, and immunosuppressants were withdrawn. Patients were followed at Weeks 4, 12, 24 and 36. Results: All patients completed four courses of low-dose rituximab infusion. At Week 4, two (20%) patients achieved complete responses (CRs, platelet count >100×10⁹/l). The CR rate increased to 60% (six patients) at Week 12, was maintained at Week 24 and began to drop at Week 36 (four patients, 40%). Overall response (OR, platelet count >50×10⁹/l) was achieved in 5/10, 6/10, 7/10 and 5/10 patients at Weeks 4, 12, 24 and 36, respectively. Peripheral CD19⁺ B cells were depleted (<5×10⁶/l) in all patients at Week 4, and gradually increased at Weeks 24 and 36. Serum C3, IgG, IgA and IgM levels did not change significantly (P<0.05). Infusion reaction was observed in two patients. One patient developed pulmonary thrombosis at Week 14 and active tuberculosis at Week 25. Conclusions: Low-dose rituximab therapy is effective in treating severe thrombocytopenia in SLE patients who do not respond to vigorous glucocorticoid plus immunosuppressants, and in most cases is safe.