Long-term effect of B-cells depletion alone as rescue therapy for severe thrombocytopenia in primary antiphospholipid syndrome.

OBJECTIVES: To investigate the long-term effect of B-cell depletion therapy with Rituximab (RTX) alone as rescue therapy in primary antiphospholipid syndrome (PAPS) patients with severe thrombocytopenia.

METHODS: We retrospectively retrieved data from patients who met the following inclusion criteria: (a) persistent antiphospholipid antibodies (aPL) positivity and fulfilled the Sydney criteria for PAPS (b) presented with severe thrombocytopenia (platelets <50,000/mm3 ) (c) were treated with RTX as a rescue therapy (d) had at least 1 year of follow-up after B-cells depletion therapy.

RESULTS: This retrospective study included 6 consecutive female PAPS patients [median age 49.5 (range 38-66)] who presented with severe thrombocytopenia (platelets <50,000/mm3 , mean value 31,000 ± 9000/mm3 ). We observed a full response (defined as >150,000 platelets/mm3 ) after treatment with RTX in 5 out of 6 patients (83.3%). Among responders, after a median follow-up of more than 4 years, we observed a median time free from relapse of 43 months (range 12-97). One patient did not respond to the B-cell depletion therapy and was treated with a splenectomy 1 month after RTX therapy and platelets levels normalized after 3 months. No adverse events were reported, no patients developed significant infections. Importantly, the patients required no further maintenance therapy for the thrombocytopenia.

CONCLUSION: In one of the longest-term observational (median 43 months) studies, sustained clinical remission of severe thrombocytopenia without immunosuppressive maintenance therapy was obtained by RTX alone in patients with PAPS and severe thrombocytopenia intolerant or refractory to conventional therapy.