Late Conversion From Calcineurin Inhibitor–Based to Sirolimus-Based Immunosuppression Due to Chronic Toxicity: A Prospective Study With Protocol Biopsy Amendment

Experience with belatacept rescue therapy in kidney transplant recipients

In kidney transplant recipients with chronic graft dysfunction, long-term immunosuppression with calcineurin inhibitors (CNIs) or mTOR inhibitors (mTORi) can be challenging due to adverse effects, such as nephrotoxicity and proteinuria. Seventy-nine kidney transplant recipients treated with CNI-based or mTORi-based maintenance immunosuppression who had CNI-induced nephrotoxicity or severe adverse events were switched to belatacept. Mean time from transplantation to belatacept conversion was 69.0 months. Mean estimated glomerular filtration rate (eGFR) ± standard deviation at baseline was 26.1 ± 15.0 ml/min/1.73 m² , increasing to 34.0 ± 15.2 ml/min/1.73 m² at 12 months postconversion (P < 0.0005). Renal function improvements were also seen in patients with low eGFR (<25 ml/min/1.73 m² ) or high proteinuria (>500 mg/l) at conversion. The Kaplan-Meier estimates for patient and graft survival at 12 months were 95.0% and 85.6%, respectively. The discontinuation rate due to adverse events was 7.9%. One case of post-transplant lymphoproliferative disorder occurred at 17 months postconversion. For comparison, a historical control group of 41 patients converted to mTORi-based immunosuppression because of biopsy-confirmed CNI-induced toxicity was examined; eGFR increased from 27.6 ± 7.2 ml/min/1.73 m² at baseline to 31.1 ± 11.9 ml/min/1.73 m² at 12 months (P = 0.018). Belatacept-based immunosuppression may be an alternative regimen for kidney transplant recipients with CNI- or mTORi-induced toxicity.

A randomized, prospective comparison of transition to sirolimus-based CNI-minimization or withdrawal in African American kidney transplant recipients

BACKGROUND

There is a lack of conclusive evidence to suggest if calcineurin inhibitor (CNI) withdrawal or minimization with sirolimus is the best strategy for African Americans.

METHODS

This was a randomized, prospective, open-label, pilot study comparing the two mammalian target of rapamycin (mTOR) transition strategies in adult African Americans between six and 24 wk post-transplant. The primary outcome was a comparison of the eGFR at one yr after conversion.

RESULTS

Forty patients were randomized and analyzed in an intent-to-treat fashion. Median day of transition was day 96 (withdrawal) and 68 (minimization). Patients in the CNI-withdrawal group (n = 23) had significantly higher eGFR at one yr compared to the CNI-minimization group (n = 17, 73 vs. 56 mL/min, p = 0.03), as well as a significantly larger increase in eGFR from baseline (12 vs. 5 mL/min, p = 0.03). There were no differences in infections, acute rejection, death, or graft loss. Both regimens were constrained by disproportionately high discontinuation rates despite modest toxicity profiles.

CONCLUSION

In spite of considerable withdrawal rate across both study arms, African American kidney transplant recipients who underwent early transition to a sirolimus-based CNI-withdrawal regimen had significantly better graft function at one yr compared to those transitioned to a sirolimus-based CNI-minimization regimen. Clinicaltrials.gov identifier: NCT01005706.