Early and Long-Lasting Hematologic Recovery in a Young Adult With Severe Aplastic Anemia Treated With Romiplostim, Horse-Anti-Thymocyte Globulin (ATG), and Cyclosporine A: A Case Report

Aplastic anemia (AA) is a rare but potentially life-threatening bone marrow failure syndrome, typically characterized by peripheral pancytopenia and marked marrow hypocellularity. In acquired cases, immune-mediated destruction of hematopoietic stem cells is the predominant mechanism; however, intrinsic stem cell defects may also contribute to marrow failure, particularly in inherited bone marrow failure syndromes. Other etiologies, such as drug-induced marrow suppression, viral infections, and radiation exposure, should also be considered in the differential diagnosis. We present the case of a 22-year-old male with newly diagnosed severe AA, who exhibited pancytopenia and hypocellular marrow devoid of dysplastic features or blast cells. Cytogenetic studies and viral serologies yielded unremarkable results. Inherited marrow failure syndromes were excluded based on clinical phenotype, cytogenetic analysis, and absence of family history, supporting the diagnosis of acquired AA. Given the lack of an HLA-matched sibling donor, combination therapy consisting of horse anti-thymocyte globulin (hATG), cyclosporine A (CsA), and romiplostim (ROMI) was promptly initiated. Hematologic improvement was observed by week two, and complete response, defined as hemoglobin ≥100 g/L, absolute neutrophil count ≥1.0 ×10⁹/L, and platelet count ≥100 ×10⁹/L-was achieved by week five. Transfusion independence was attained early in the course, and no serious adverse events were observed. This case underscores the potential utility of early triple immunosuppressive therapy (IST) in treatment-naïve severe AA, particularly among younger patients, where prompt immunosuppressive intervention may accelerate hematologic recovery and support the preservation of marrow architecture.