Introduction: HS patients not desensitized (DES) receiving transplants are at risk for ABMR. DES improves transplant rates, but is limited to donor availability. Implementation of the new kidney allocation (KAS) is intended to improve transplant opportunities for these difficult to match patients. Here we assessed the impact of the new allocation system on DD offers and transplant rates for CPRA 99-100%. Patients & Methods: We assessed transplant rates and outcomes in HS patients (CPRA>80%) who underwent DES with IVIG (2gm/kg, maximum 140gm x2 doses) + rituximab (x1) ± PLEX and were transplanted prior to and after implementation of new KAS (pre-KAS, G1 & post-KAS, G2). In preparation for implementation of the new KAS, we reviewed our wait-list for patients who would meet criteria for CPRA>80% and likely be transplanted w/in 6M. Identified patients received medical clearance and initiated DES. Transplanted patients in both groups received induction with alemtuzumab x1 & maintained with tac/mmf/pred taper. Results: From 1/1/14 to 12/6/14, 32 HS patients received transplants (G1) v. 29 HS patients transplanted from 12/8/14 to 11/22/15 (G2). Transplant rates for G1: CPRA 80-98% = 31 (97%); 99-100% = 1 (3%) v. G2: CPRA 80-98% = 18 (62%); 99-100% = 11 (38%); p-value =0.0006 for CPRA 99-100% G1v.G2. ABMR occurred in G1: 8 (25%; CPRA 80-98% = 8 [7 DSA+ @Tx, 1 dnDSA+]) v. G2: 1 (3.4%; CPRA 80-98%, DSA+ @Tx) (p=0.017). Patient and graft survival were 100%/97% (G1) v. 100%/93% (G2) (p=NS). Conclusions: Rates of transplant for our HS patients with CPRA 99-100% increased significantly from 2.9% to 38% (p=0.0006) likely d/t increased regional and national access to a compatible donor pool in HS patients after preemptive DES. In addition, rate of ABMR in G1 was significantly higher compared to G2 (25% v. 3.4%, p=0.017). Possible reason for increased rate of ABMR in G1 could reflect longer observation (24M follow-up). Pre-emptive DES likely does contribute to decreased risk for the observed rate of ABMR. Therefore, it is critical to consider pre-emptive DES for 99-100% CPRA group (even with DSA- @Tx) as these patients are likely to have memory B-cell responses that result in DSA rebound and ABMR after transplant with a significant impact on long-term graft survival.

CITATION INFORMATION: Vo A, Zhang X, Williamson S, Myers K, Reinsmoen N, Choi J, Kahwaji J, Peng A, Villicana R, Jordan S. Impact of the New Kidney Allocation System (KAS) on Transplant Rates & Outcomes in Broadly-HLA Sensitized (HS) Patients Transplanted After Desensitization (DES). Am J Transplant. 2016;16 (suppl 3).

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