The Changing Landscape of Treatment in Pediatric Aplastic Anemia; A Single Institution's Experience

Introduction: Aplastic anemia (AA) is a rare syndrome of bone marrow failure characterized by peripheral blood pancytopenia and marrow aplasia. We report the clinical course and therapeutic approach of children with AA, who were treated in our Department within the last 4 years. Methods: Fifteen children (9 males/ 6 females) of mean age 7.64 years (range: 2 to 15 years) were diagnosed in our unit with AA since 2012. Diagnosis was established by bone marrow aspirate and biopsy and a normal bone marrow karyotype. Evaluation for underlying bone marrow failure syndromes, including Fanconi anemia, Shwachman-Diamond syndrome and paroxysmal nocturnal hemoglobinuria was performed in all cases. Results: Four children were identified with Fanconi anemia, both by cytogenetic and molecular analysis. Eleven children were diagnosed with acquired aplastic anemia (AAA); one probably after treatment with NSAIDs, one patient presented after influenza virus infection, while two patients presented also with transaminasemia of unknown etiology. First line therapy was hematopoietic stem-cell transplantation (HSCT), should an appropriate graft be available. In this respect, three patients (N: 3/4 ) with Fanconi anemia and one patient (N:1/11) with AAA were transplanted from a fully-matched sibling donor. One patient with AAA received autologous cord blood. The remaining ten patients (N: 10/15) received standard immunosuppressive therapy (antithymocyte globulin, cyclosporine-A and methylprednisolone). Eight of the 9 evaluable patients responded to therapy. Six of these patients also received treatment with eltrombopag, an oral thrombopoietin-receptor agonist, for at least six months. Eltrombopag was provided as off-label compassionate use and after having received approval from regulatory authorities. In these 6 patients, treatment with eltrombopag was well tolerated with no additive toxicity. Five patients showed progressive improvement of hematological values during the treatment with eltrombopag. Two patients with AAA, did not respond to immunosuppressive therapy, and subsequently underwent MUD-HSCT. One succumbed due to severe autoimmune hemolytic anemia, while the second has showed good engraftment, but with short post-BMT follow up time. Of note is, that one patient with Fanconi anemia showed full hematological recovery after immunosuppressive treatment. This patient, who was found to be homozygous for a FANC-E mutation, did not have any clinical stigmata. It is speculated that the unusual response to therapy may be due to its very mild clinical phenotype. Conclusions: Survival rates in severe AA have remarkably improved in the last decades due to allo-HSCT, immunosuppressive therapy and intense supportive care. This small series of children with AA underlines the option of new effective modalities. The use of autologous umbilical cord blood should be considered as an alternative first line therapy. Eltrombopag seems to improve platelet count and result in a tri-lineage response, in a manner similar to the one observed in adults with AA. Finally, the efficacy of immunosuppressive treatment in a patient with Fanconi anemia has not been previously described and warrants further evaluation.