Because of inability to get FDA approval for

The purpose of this study is to determine the safety and feasibility of converting patients to Belatacept monotherapy (receiving just one immunosuppression drug), and to see what percentage of those patients can be safely converted to once every 8 week administration of Belatacept. Belatacept has been approved by the Food and Drug Administration (FDA) for kidney transplant recipients.

Patients on belatacept who fulfill the entry criteria will be screened to determine if they have a quiescent molecular immunologic profile with kSORT and uCRM. Patients who screen negative on all 2 tests will undergo stepwise withdrawal first of steroids then of MMF or mTor inhibitors. Prior to each withdrawal the 2 screening molecular tests will be performed and advancement to the next withdrawal phase will be performed if both are negative. Patients who are maintained on belatacept monotherapy with quiescent kSORT and uCRM and elevated kSPOT will be transitioned to q 8 weeks belatacept administration.

Forty patients who are previously enrolled in belatacept based regimens with a minimum of 7 years of follow up at 4 transplant centers and who are maintained on belatacept, an antiproliferative ± steroids will be approached for enrollment.

Drug withdrawal of steroids (in patients on steroids) and of antiproliferatives (MPAs or mTor inhibitors) will follow the design shown in the Study Schema. Patients who continue to be stable for 3 months on belatacept monotherapy will be converted from q 4 weeks to q 8 weeks belatacept administrations.

Inclusion Criteria:

• Stable renal function with a GFR ≥ 35 ml/min
• No history of acute rejection
• A spot urine protein creatinine ratio of 0.5 or less
• No DSA

Entry: Biomarker criteria

• Blood kSORT and urine CRM tests that are quiescent at entry and following each drug withdrawal.
• A third biomarker KSPOT will be used to assess if any patients has achieved tolerance.

Eligibility for 8 week Belatacept Administration

• Trough levels of belatacept at 4 weeks of greater than 2 µg/ml
• Trough levels of belatacept at 8 weeks of equal or greater than 1 µg/ml

Exclusion Criteria:

• Patients with < eGFR (35 ml/min)
• History of rejection
• Protein/creatinine rate >0.5
• Presence of DSA