TBF + anti-thymocyte globulin + cyclophosphamide

TBF + anti-thymocyte globulin + cyclophosphamide is a combination conditioning regimen used primarily in the context of allogeneic hematopoietic stem cell transplantation (HSCT), especially for severe aplastic anemia and other hematologic disorders. The regimen typically includes: - **TBF** (Thiotepa, Busulfan, Fludarabine): A myeloablative or reduced-intensity conditioning backbone that provides immunosuppression and cytoreduction. - **Anti-thymocyte globulin (ATG)**: A polyclonal antibody preparation targeting human T cells, leading to profound T-cell depletion via complement-mediated lysis and apoptosis. This reduces the risk of graft rejection and graft-versus-host disease (GVHD) by suppressing host immune responses[1][9]. - **Cyclophosphamide**: An alkylating agent with both cytotoxic and immunosuppressive properties, used to further deplete lymphocytes and enhance engraftment[6][8]. This combination is designed to optimize engraftment rates while minimizing GVHD risk. ATG modulates immune function through multiple mechanisms including depletion of peripheral T cells, modulation of leukocyte-endothelial interactions, induction of B cell apoptosis, interference with dendritic cell function, and promotion of regulatory T cells[1][9]. Cyclophosphamide adds additional immunosuppression by cross-linking DNA in rapidly dividing immune cells[6][8]. The overall goal is durable donor engraftment with manageable toxicity.