alemtuzumab + busulfan + clofarabine

A combination conditioning regimen used prior to hematopoietic stem cell transplantation for patients with hematologic malignancies. The regimen consists of three distinct medications: 1. **Alemtuzumab**: A humanized monoclonal antibody that targets CD52, a cell surface glycoprotein present on T and B lymphocytes, natural killer cells, monocytes, and macrophages. It causes depletion of these cells through antibody-dependent cellular cytolysis and complement-mediated lysis. 2. **Busulfan**: An alkylating agent used in conditioning regimens prior to allogeneic hematopoietic stem cell transplantation, particularly for leukemias. 3. **Clofarabine**: A second-generation purine analog that requires intracellular phosphorylation to be active. Its triphosphate form impedes DNA synthesis and repair by inhibiting ribonucleotide reductase and DNA polymerase. The combination is used as a conditioning regimen prior to allogeneic hematopoietic stem cell transplantation for patients with various hematologic malignancies, including acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and myelodysplastic syndromes (MDS).