MO982COMPARISON OF BASILIXIMAB AND R-ATG ON ACUTE REJECTION RISK IN HIGH IMMUNOLOGICAL RISK RENAL TRANSPLANT RECIPIENTS

Background and Aims High Panel Reactive Antibody (PRA) level has been widely accepted as a marker for acute rejection risk following kidney transplantation. PRA>/= 20% is considered a high immunological risk renal transplant. The aim of our study was to assess the risk of acute rejection in kidney transplant recipients (KTR) following Basiliximab induction compared to Rabbit Anti-Thymocyte Globulin (R-ATG) maintained on tacrolimus and mycophenolate mofetil maintenance immunotherapy. Method This was a retrospective observational cohort study using data from the United States Organ Procurement and Transplantation Network, all KTR’s with PRA =/> 20%, who were maintained on tacrolimus and mycophenolate mofetil between September 2017 and September 2019 were included. Follow-up was until September 2020. Data included recipient factors (age, sex, ethnicity, diabetes, body mass index), transplant factors (delayed graft function, cold ischemia time, number of previous transplants, panel reactive antibodies, HLA-mismatches, induction therapy, maintenance immunotherapy and donor factors (donor type, donor age). The cohort were divided into 2 groups; living and deceased donor renal transplants. The groups were further divided by PRA level, each group was divided into 3 subgroups: Group A (low PRA level: PRA range from 20% to 49%), Group B (moderate PRA level: PRA range from 50% to 79%), and Group C (High PRA level: PRA range from 80% to 100%). Multivariable logistic regression models were constructed to assess the effect of induction therapies (Basiliximab versus R-ATG) on acute rejection episodes at 6 months post-transplant. The multivariable model was adjusted for recipient, donor and transplant factors mentioned above. Results Among living donor KTR’s, there was no difference between Basiliximab and R-ATG in acute rejection episodes in any of the three groups, Group A (low PRA level, n=717, OR=1.17, P=0.79, 95%CI:0.34-3.95), Group B (moderate PRA level, n=618, OR=1.51, P=0.58, 95%CI:0.33-6.92) and Group C (high PRA level, n=401, OR=1.17, P=0.85, 95%CI:0.21-6.56) respectively. In contrast, among deceased donor KTR’s R-ATG was associated with lower risk of rejection compared to Basiliximab in all three groups, group A (low PRA level, n=1895, OR=0.52, P=0.03, 95%CI: 0.28-0.94), group B (moderate PRA level, n=1618, OR=0.41, P<0.01, 95%CI: 0.22-0.78) and group C (high PRA level, n=3973, P<0.01, 95%CI: 0.28-0.70). Conclusion This study shows that risk of acute rejection is no different with Basilximab induction compared to R-ATG in high immunological risk living-donor KTR’s at all levels of PRA in the current tacrolimus-mycophenolate mofetil immunosuppression era. However, risk of acute rejection seems to be lower in deceased donor KTR’s having R-ATG induction at all levels of PRA. Delayed graft function is a risk factor for acute rejection, our models did not adjust for dose of R-ATG which may explain the lower risk seen in deceased donor KTR’s, data was not available on donor specific antibodies. In summary, Basiliximab induction has similar acute rejection rates as R-ATG in living donor KTR’s whereas in deceased donor KTR’s R-ATG was found to be better.