busulfan + Campath-1H + cyclophosphamide

This is a combination regimen consisting of three agents: - **Busulfan** is an alkylating agent that cross-links DNA, leading to inhibition of DNA replication and transcription, ultimately causing cell death. It is primarily used as part of conditioning regimens prior to hematopoietic stem cell transplantation (HSCT) for various hematologic malignancies and nonmalignant diseases. - **Campath-1H** (alemtuzumab) is a humanized monoclonal antibody targeting CD52, a protein present on the surface of mature lymphocytes. It induces antibody-dependent lysis and depletion of lymphocytes, providing immunosuppression. - **Cyclophosphamide** is another alkylating agent that interferes with DNA replication by forming cross-links in DNA strands. It has cytotoxic effects on both malignant and normal proliferating cells. The combination regimen "busulfan + Campath-1H + cyclophosphamide" is used as a conditioning protocol before allogeneic or autologous stem cell transplantation to eradicate malignant cells, suppress the immune system to prevent graft rejection, and facilitate engraftment[4][7]. This specific triple-drug combination may be selected for its synergistic cytotoxicity against hematologic malignancies while providing potent immunosuppression.