D142 - Single Low-Dose RATG (3 mg/kg) within 24 Hours Post-Transplant Improves Long-Term Outcomes in Low-Immunological-Risk Kidney Transplant Recipients

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Author Block: G. C. Consani¹, C. Albuquerque¹, M. de Paula², R. Demarchi Foresto², J. Medina-Pestana², L. Requião-Moura³, ¹Universidade Federal de São Paulo, Sao Paulo, Brazil, ²Hospital do Rim – Fundação Oswaldo Ramos, Sao Paulo, Brazil, ³Nephrology Division, Universidade Federal de São Paulo, São Paulo, Brazil
*Purpose: We previously showed that a reduced single dose of Thymoglobulin (RSD-rATG, 3 mg/kg) administered within 24 hours after kidney transplantation was associated with an 85% reduction in 1-year acute rejection (AR) among low immunological risk kidney transplant recipients (LR-KTRs). Here, we report the 10-year extension of this cohort, evaluating graft survival, kidney function, and post-transplant lymphoproliferative disease (PTLD).
*Methods: We conducted a before-and-after quasi-experimental propensity score-matched study including 931 LR-KTRs across two eras: no induction (control; before June/2014) and RSD-rATG (after; June/2014 to September/2015), with up to 10 years of follow-up. The 3-year extension outcome was AR. Ten-year outcomes included graft survival, estimated glomerular filtration rate (eGFR, CKD-EPI 2021), and PTLD. Cumulative incidence, survival, and relative risk were estimated using the Kaplan-Meier and Cox regression methods. Longitudinal eGFR trajectories were modeled using linear generalized estimating equations adjusted by the Bonferroni test.
*Results: At 3 years, the cumulative incidence of AR was 11.4% in the RSD-rATG group versus 54.1% in controls (HR 0.15; 95% CI 0.11-0.20; p<0.001). The additional incidence of AR between 1 and 3 years was 4% in the RSD-rATG group versus 13% in controls (p<0.001), corresponding to a 68% relative risk reduction (HR 0.52; 95% CI 0.29-0.94; p=0.03). At 10 years, overall graft survival was higher with RSD-rATG (63.9% vs. 55.5%; p=0.04). Stratified by donor type, graft survival was 73.6% vs. 70.9% for living donor recipients (p=0.33) and 59.1% vs. 48.1% for deceased donor recipients (p=0.03) in the RSD-rATG and control groups, respectively. Among living donor recipients, mean eGFR declined by 11.6 mL/min/1.73 m² (95%CI -15.3 to -7.8; p<0.001) from 1 to 10 years, with no significant difference between groups (p=0.78) or time-group interaction (p=0.12). Among deceased donor recipients, mean eGFR declined by 9.9 mL/min/1.73 m² (95%CI -12.4 to -7.4; p<0.001), with a higher mean eGFR in the RSD-rATG group (mean difference 4.2 mL/min/1.73 m²; 95% CI 0.29-8.12; p=0.03) and no significant time-group interaction (p=0.82). PTLD occurred in 16 patients, with an overall incidence of 1.4 cases per 1,000 patients-year, similar between groups (HR 1.00; 95% CI 0.37-2.66; p=1.00).
*Conclusions: In LR-KTRs, a single 3 mg/kg dose of rATG given within 24 hours after transplantation confers sustained protection against AR beyond the first year and is associated with improved long-term graft survival and kidney function in deceased donor recipients, without increasing the long-term risk of PTLD.