Long-Term Safety and Efficacy of Tegoprubart in Kidney Transplant Recipients

This study will evaluate the long term safety and efficacy of AT-1501 (tegoprubart) compared with tacrolimus in patients undergoing kidney transplantation.

This is a multicenter, open-label, active control extension study to assess the long-term safety and efficacy of AT-1501 (tegoprubart) compared with tacrolimus in the preservation of allograft function after kidney transplantation. The number of patients enrolled for OLE study will depend on the enrollment in the Parent studies. To be eligible for participation in this study, participants must have completed a designated Parent study. Participants in this study will continue the treatment regimen they were receiving in the Parent study. Dose regimens will include either AT-1501 (tegoprubart) or tacrolimus.

Inclusion Criteria: * Successfully completed qualifying Parent study, where entry into the OLE was offered; * Continue to be able to understand the key components of the study as described in the written ICF, and is willing and able to provide written informed consent; * Agree not to participate in another interventional study while on treatment; * If female, is surgically sterile or 2 years postmenopausal. Women of childbearing potential may be enrolled if a pregnancy test is negative at baseline. Women of childbearing potential and men with partners that are of childbearing potential must agree to use highly effective methods of contraception from baseline, through 90 days after the last administration of the study drug. Examples of acceptable methods of contraception are described in Table 6. * If male, agree to use a medically accepted highly effective method of contraception and agree to use this method for 90 days after last administration of the study drug and agree to not donate sperm for 90 days after last administration of the study drug. Exclusion Criteria: * Unwilling or unlikely to comply with the study requirements, in the opinion of the Investigator; * Met any of the stopping criteria or discontinued study drug in the Parent study; * Pregnant or breastfeeding.