Safety, Pharmacokinetics, and Efficacy of AT 1501 in Patients Undergoing Kidney Transplant

Inclusion Criteria: 1. Male or female ≥ 18 years of age 2. Recipient of their first kidney transplant from a living or deceased donor 3. Agree to comply with contraception requirements during and for at least 90 days after the last administration of study drug Exclusion Criteria: 1. Induction therapy, other than study assigned rATG, planned as part of initial immunosuppressive regimen 2. Currently treated with any systemic immunosuppressive regimen, including immunologic biologic therapies, with the exception of 5 mg prednisone or equivalent daily; 3. Previous treatment with AT 1501 or any other anti CD40LG therapy 4. The patient has previously received a bone marrow transplant or any other solid organ transplant, including a kidney, or will be undergoing a multi organ or dual kidney transplant 5. Will receive a kidney with an anticipated cold ischemia time of \> 30 hours; 6. Will receive a kidney from a donor that meets any of the following criteria: * Donation after Cardiac Death (DCD) criteria; or * Extended Criteria Donor (ECD) criteria, defined as: * Is blood group (ABO) incompatible; or * Age ≥ 60 years; or Age 50-59 years with any 2 of the following criteria: * Death due to cerebrovascular accident * History of hypertension * Terminal creatinine ≥ 133 μmol/L (1.5 mg/dL) 7. Human leukocyte antigen identical (two haplotype match or zero HLA mismatch) donor 8. Medical conditions that require chronic use of systemic steroids at a dose higher than 5 mg prednisone or equivalent per day 9. History of a TE event, known hypercoagulable state, or condition requiring long term anticoagulation: 10. Positive T- or B-cell crossmatch that is due to HLA antibodies or presence of a DSA at Screening