Belatacept in De Novo Heart Transplantation

Inclusion Criteria:

1. Male or non-pregnant female, age ≥18 to ≤75 years

2. Awaiting a primary heart transplant (listed for heart transplant only)

3. Epstein-Barr virus (EBV) IgG seropositive

4. Able to take oral medication and willing to adhere to the belatacept infusionregimen

5. No desensitization therapy prior to transplant

6. Vaccinations should be up to date for hepatitis B, influenza pneumococcal,haemophilus, varicella zoster virus (VZV), measles, mumps and rubella (MMR), andHuman Papilloma Virus (HPV) (for participants < 45 years of age) when available

7. Female subjects of childbearing potential must have a negative pregnancy test (serumor urine) prior to randomization

8. Mechanical support or investigational drug trials where the intervention ends at thetime of transplantation are permitted

9. Negative virtual crossmatch

Exclusion Criteria:

1. Candidates awaiting multiorgan transplant

2. Estimated glomerular filtration rate (eGFR) < 45 ml/min/m2

3. Candidates with prior organ transplant

4. Candidates actively being treated with immunosuppressive therapies

5. Candidates who have a history of treatment with cytolytic therapy (e.g.anti-thymocyte globulin)

6. Candidates who are intended to be treated with cytolytic therapy in thepost-transplant period as induction therapy

7. EBV (IgG) seronegative

8. Active or prior infection with human immunodeficiency virus (HIV), Hepatitis C (HCV), Hepatitis B (HBV)

9. Untreated latent tuberculosis (TB)

10. All potential candidates will be screened prior to enrolment for a history oftuberculosis (chest radiograph and tuberculosis-Interferon Gamma Release Assay (TB-IGRA) or tuberculin skin tests (TST)). Potential candidates with latent TB mustbe treated prior to study enrolment

11. Prior history of active tuberculosis

12. Prior history of central nervous system infection

13. Known active current viral, fungal, mycobacterial, or other infections excludingdriveline infections - potential participants from endemic areas will additionallybe screened for histoplasmosis, blastomycosis, coccidioidomycosis, andstrongyloidiasis

14. Vaccination with a live vaccine within the past 30 days

15. Malignancy within the last 5 years

16. Any previous treatment with alkylating agents or total lymphoid irradiation

17. Sensitized heart transplant candidates with panel-reactive antibodies (PRA) >50% orthose receiving desensitization treatment

18. Prior treatment with belatacept or abatacept

19. History of severe allergic anaphylactic reactions to humanized or murine monoclonalantibodies

20. Treatment with a disease modifying anti-rheumatic drug (DMARD) or other biologicagent (monoclonal antibody) within the past year

21. Treatment with another investigational drug or other intervention at the time oftransplant (excluding device or intervention mechanical support or investigationaldrug trials where the intervention ends at the time of transplant)

22. Potential candidates for whom a calcineurin inhibitor other than tacrolimus (Prograf®) is anticipated after transplant. If during the course of the study, aparticipant is transitioned to another calcineurin inhibitor due to side effects orinability to achieve stable therapeutic trough levels, they may continue in thestudy at the discretion of the investigator

23. Any potential participant who remains on mechanical circulatory support for > 72hours post-transplant will be excluded from the study

24. The need for ongoing high dose vasopressor support > 72 hours post-transplant

25. The need or anticipated need for post-transplant dialysis

26. Platelet count <75,000/mm (within 24 hours prior to transplant)

27. Absolute neutrophil count (ANC) of less than 2000/mm3 within 24 hours prior totransplant

28. Any past or current medical problems or findings on history, physical examination,or laboratory testing, not listed above, that in the opinion of the investigator,may pose additional risk to participation, may interfere with the participant'sability to comply with study requirements, or that may impact the quality orinterpretation of study results