Successful treatment of refractory secondary immune thrombocytopenia (antiphospholipid antibody syndrome-associated) with the combination of rituximab and romiplostim at the cost of severe bone pain: A case report and review of literature.

Introduction: Immune thrombocytopenia is an autoimmune disorder associated with increased thrombocyte destruction and impaired production in the bone marrow. Proposed mechanisms include an antibody or autoreactive T-cell-associated autoimmunity and thrombopoietin deficiency among others. Clinical manifestations are predominantly mucocutaneous hemorrhages including petechiae, purpura, mucosal bleeding in the urinary or the gastrointestinal tracts, menorrhagia, and epistaxis. The purpose of the treatment is to prevent bleeding rather than normalizing the platelet counts. First-line treatments include corticosteroids ± intravenous immunoglobulin and Anti-D which mainly decrease antibody-mediated platelet destruction and increase the number of peripheral Tregs. Second-line and subsequent therapies include splenectomy, chimeric anti-CD20 antibody (rituximab), which eliminates B cells and act as an immunomodulatory agent, and Thrombopoietin receptor agonists (romiplostim), which promote platelet production.
Case Report: We describe a 40-year-old male patient diagnosed with immune thrombocytopenia that was refractory to first-line corticosteroid and intravenous immunoglobulin and second-line romiplostim monotherapy treatments. Management and outcome: The patient was given the romiplostim and rituximab combination which not only successfully treated thrombocytopenia but also resulted in grade 3 bone pains and the patient's subsequent refusal to continue therapy.
Discussion: Common adverse effects of rituximab are infusion reactions and prolonged immunosuppression; those of romiplostim include thrombosis, headaches, arthralgia-myalgia, and gastrointestinal symptoms. This case shows that romiplostim has not caused any discernible side effects when given alone, while combination with rituximab resulted in severe bone and joint pains. We hypothesize that this combination regimen shows a synergistic effect both in terms of efficacy and adverse-effect probability and/or severity.