A Study Comparing Siplizumab With Rabbit Anti-Thymocyte Globulin to Help the Body Accept a Kidney Transplant

Inclusion Criteria: * Recipients of a renal allograft from a non-HLA identical living or deceased donor. * Recipients of a kidney with a cold ischemia time \< 30 hours; hypothermic machine perfusion within the same timeframe is acceptable. * Women of childbearing potential, defined as all women physiologically capable of becoming pregnant, must agree to use highly effective methods of contraception. Exclusion Criteria: * Transplant recipients seronegative for EBV. * Transplant recipients receiving a kidney from a non-heart beating donor (ie, DCD) whose organ is retrieved from an uncontrolled DCD or whose donor age \> 55 years of age. * Multi-organ transplant recipients (eg, kidney-pancreas, organ other than kidney), dual-kidney transplant recipients, recipients with more than one prior kidney transplant, or hematopoietic stem cell transplantation recipients. * Presence of current or historical DSA via single-antigen bead assay or local SoC. The MFI cut-off value used to determine the presence of DSA will be defined as per the institutional SoC. Results within 3 months prior to transplant are acceptable. * Crossmatch positive (isolated positive B cell crossmatches are not an exclusion criterion). * ABO-incompatible recipient. * Administration of complement inhibitor therapy within 6 months prior to the transplant, or likely to require treatment with complement inhibitor therapy during the study. * Participants receiving immunosuppressive therapies prior to transplant for pre-existing conditions must be candidates for the protocol-defined regimen. * History of malignancy of any organ system, except for localized excised non-melanomatous skin lesions or carcinoma in situ of the cervix. * Seropositive for human immunodeficiency virus or hepatitis B surface antigen. Participants who are seropositive for hepatitis C virus (HCV) are excluded without proof of sustained viral response after anti-HCV treatment. * Recipient of a kidney from a donor who tests positive for human immunodeficiency virus or hepatitis B surface antigen/hepatitis B core protein. * History of hypersensitivity to any of the study drugs or to drugs of similar chemical classes (eg, siplizumab, rATG, TAC, MPA derivatives, CS). * Evidence of active tuberculosis (TB) infection (participants with a history of latent TB may become eligible after treatment with anti-TB therapy according to national guidelines). * Participants with severe systemic infection(s), at the time of screening or within 2 weeks prior to randomization