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Successful Treatment of Post-Transplant Immune Thrombocytopenia with Romiplostim in a Pediatric Patient with X-Linked Chronic Granulomatous Disease
Romiplostim is a thrombopoietin receptor agonist utilized in the treatment of pediatric patients with immune thrombocytopenia. Furthermore, the limited toxicity of romiplostim makes this an attractive option for the treatment of post-HSCT immune thrombocytopenia. We describe a 3-year-old male with X-linked chronic granulomatous disease (CGD) treated with unrelated donor HSCT. His course was complicated by immune dysregulation manifest as recurrent pleural effusions that improved with corticosteroids. At 1-year post HSCT, after stopping his corticosteroids he developed symptomatic thrombocytopenia and autoimmune hemolytic anemia (AIHA). He was started on romiplostim with improvement in his thrombocytopenia.
Methods:
A 3-year-old Asian male was diagnosed with X-CGD. The patient underwent HSCT utilizing a 9/10 HLA matched unrelated female donor. The preparative regimen was: busulfan (0.8 mg/kg/dose x 16 doses), cytoxan (50 mg/kg/dose x 4 doses), fludarabine (30mg/m2) and Campath (2 mg x 4 doses). Graft-versus-host disease prophylaxis was: cyclosporine and methotrexate. Post-HSCT he developed seizures and mucositis. He engrafted on Day +18 with 100% donor engraftment. On Day +62 and +119 he presented with symptomatic pleural effusions. Evaluation for infectious pathogens was negative. On both occasions a response to corticosteroids was documented. At 1-year post-HSCT as his corticosteroid taper finished he developed symptomatic thrombocytopenia (platelet count 5,000 / uL).
Results:
He was treated with intravenous immunoglobulin and platelet transfusion without significant improvement. In addition to symptomatic thrombocytopenia a warm AIHA (hemoglobin 5.2 g / dL) emerged. Evaluation for infectious pathogens was negative. A bone marrow examination demonstrated a cellular marrow with trilineage hematopoiesis, megakaryocytic hypoplasia, and erythroid hyperplasia. Cytogenetic evaluation demonstrated a normal male karyotype and chimerism studies documented 98% donor engraftment. In order to avoid the toxicity associated with corticosteroid use romiplostim was started at 5 mcg/kg subcutaneous each week. Within three 3 weeks of starting therapy his platelet count was > 50,000 / uL. He continues to maintain a platelet count > 100,000 / uL while tapering his romiplostim dose. His hemoglobin also continued to improve without a need for transfusion support.
Conclusion:
To our knowledge, this is the first description of a successful application of romiplostim as initial therapy in a pediatric patient with immune thrombocytopenia following matched unrelated donor HSCT for X-linked CGD. We found that the use of romiplostim to be an effective and safe alternative to the potential morbidity and mortality associated with the use of immunosuppressive agents such as corticosteroids.