Long-term outcomes in rapamycin on renal allograft function: a 30-year follow-up from a single-center experience.

Objectives: To evaluate long-term renal graft prognosis and the role of rapamycin from a single-center in China over a 30-year follow-up.

Methods: This study enrolled a total of 654 patients who underwent kidney transplantation between 1989 and 2020. The basic characteristics of the included patients were collected. Graft survival was described and compared using Kaplan-Meier curves (K-M curves). Both continuous and categorical variables were included in a multivariate Cox proportional-hazards model. Patients were divided into rapamycin-based quadruple immunosuppression regimen group (rapa group, n = 41) and conventional tacrolimus-based triple immunosuppression regimen group (control group, n = 218). The indication biopsy results of the two groups were further reviewed to compare the incidence of rejection, acute rejection, and banff score.

Results: The overall 5, 10, 15, 20-year graft survival rate of our center is 87.5%, 62.4%, 46.4% and 20.9%, respectively. The median survival time after surgery is 14 years. Multiple Cox regression analysis identified BMI (p = 0.035), dialysis type (p < 0.001), immunosuppressants (p < 0.01), urine albumen (p < 0.001), globulin (p = 0.041), and blood glucose (p = 0.002) as risk factors. The 20-year, 10-year and 5-year AUC is 0.78, 0.75 and 0.75. The combination of FK506 and rapamycin was further suggested by the model to effectively improve the graft prognosis (p < 0.01, HR = 0.763). The K-M curve showed that the long-term survival rate of renal grafts in the rapa group was significantly better than that in the conventional group (p < 0.001). In addition, indication biopsy records revealed a lower possibility of immune rejection in the rapa group than that in the conventional group (p < 0.001). Banff score indicated that rapa group had less vascular inflammation in the transplanted kidney.

Conclusions: In this study, a 30-year follow-up was performed in a single center, and a total graft 20-year survival rate of 20.9% was reported. The prognostic model and subgroup analysis suggested that FK506 combined with rapamycin could effectively improve the prognosis of renal transplantation, which could be explained by reduced acute rejection and less vascular inflammation.