Conversion from Calcineurin Inhibitor– to Belatacept-Based Maintenance Immunosuppression in Renal Transplant Recipients: A Randomized Phase 3b Trial
Authors: Budde Klemens , Prashar Rohini , Haller Hermann , Rial Maria C. , Kamar Nassim , Agarwal Avinash , de Fijter Johan W. , Rostaing Lionel , Berger Stefan P. , Djamali Arjang , Leca Nicolae , Allamassey Lisa , Gao Sheng , Polinsky Martin , Vincenti Flavio 
Published: November 2021

Significance Statement
This randomized trial demonstrates the safety and efficacy of conversion from calcineurin inhibitor (CNI)– to belatacept-based maintenance immunosuppression in renal transplant recipients 6–60 months post-transplant. Patients converted to belatacept showed sustained improvement in renal function associated with an acceptable safety profile consistent with prior experience and a smaller treatment difference in acute rejection postconversion compared with that observed in earlier studies in de novo renal allograft recipients. These results favor the use of belatacept as an alternative to continued long-term CNI-based maintenance immunosuppression, which is particularly relevant for CNI-intolerant patients, including those who experience nephrotoxicity. These data help inform clinical practice guidelines regarding the conversion of such patients to an alternative immunosuppressive drug regimen.

Background
Calcineurin inhibitors (CNIs) are standard of care after kidney transplantation, but they are associated with nephrotoxicity and reduced long-term graft survival. Belatacept, a selective T cell costimulation blocker, is approved for the prophylaxis of kidney transplant rejection. This phase 3 trial evaluated the efficacy and safety of conversion from CNI-based to belatacept-based maintenance immunosuppression in kidney transplant recipients.

Methods
Stable adult kidney transplant recipients 6–60 months post-transplantation under CNI-based immunosuppression were randomized (1:1) to switch to belatacept or continue treatment with their established CNI. The primary end point was the percentage of patients surviving with a functioning graft at 24 months.

Results
Overall, 446 renal transplant recipients were randomized to belatacept conversion (n=223) or CNI continuation (n=223). The 24-month rates of survival with graft function were 98% and 97% in the belatacept and CNI groups, respectively (adjusted difference, 0.8; 95.1% CI, −2.1 to 3.7). In the belatacept conversion versus CNI continuation groups, 8% versus 4% of patients experienced biopsy-proven acute rejection (BPAR), respectively, and 1% versus 7% developed de novo donor-specific antibodies (dnDSAs), respectively. The 24-month eGFR was higher with belatacept (55.5 versus 48.5 ml/min per 1.73 m2 with CNI). Both groups had similar rates of serious adverse events, infections, and discontinuations, with no unexpected adverse events. One patient in the belatacept group had post-transplant lymphoproliferative disorder.

Conclusions
Switching stable renal transplant recipients from CNI-based to belatacept-based immunosuppression was associated with a similar rate of death or graft loss, improved renal function, and a numerically higher BPAR rate but a lower incidence of dnDSA.

Clinical Trial registry name and registration number: A Study in Maintenance Kidney Transplant Recipients Following Conversion to Nulojix® (Belatacept)-Based, NCT01820572