alemtuzumab + cyclophosphamide + sirolimus

A combination immunosuppressive regimen consisting of alemtuzumab (a monoclonal anti-CD52 antibody), cyclophosphamide (an alkylating agent), and sirolimus (an mTOR inhibitor). This combination is used primarily in transplantation protocols, particularly for hematopoietic stem cell transplantation in conditions like sickle cell disease. The regimen works through complementary mechanisms: alemtuzumab depletes T and B lymphocytes through antibody-dependent cellular cytolysis, cyclophosphamide prevents cell division by cross-linking DNA, and sirolimus inhibits T-lymphocyte activation and proliferation by blocking mTOR signaling. This combination aims to prevent graft rejection and graft-versus-host disease while promoting engraftment.