P076 Alloantibody desensitization outcomes: PRA levels, CPRA or antibody titers; how to use them best

Abstract

Aim Desensitization protocols that include IVIG, plasmapheresis have been utilized by multiple groups with different levels of success. More recently, Rituximab and Bortezomib have been studied as part of desensitization therapies, but the data to support the utility and safety of these agents to reduce PRA is still debatable. This retrospective IRB approved study, looked at patients listed at Tampa General Hospital from 10/2011 to 10/2014. These patients were categorized into 3 different groups: non sensitized, sensitized non treated and sensitized treated. Sensitization was defined as a Percent Reactive Antibody (PRA) > 10%. The aim of this study was to evaluate the effects of PRA and HLA antibody specificity and titers, to best evaluate the efficacy of treatment. Methods % Class I and II PRA was measured by Flow PRA beads and antibody specificity/titers, using Luminex SAB (One Lambda, Canoga Park, CA). Results From 10/2011 to 10/2014, 164 heart transplant patients were listed for transplantation. Fifteen of the 58 sensitized patients (25.9%) underwent desensitization therapy. Patients on desensitization, all received plasmapheresis and IVIG, with a median of 3 monthly cycles. Eleven of the 15 patients (73.3%) also received Rituximab therapy. Two of the 15 (13.3%) received Bortexomib therapy after at least 2 cycles of plasmapheresis, IVIG and Rituximab with no significant decrease in HLA antibody by any of the methods tested. Twelve out of the 15 patients (80%) were transplanted. Eight out of 15 (53%) of patients showed no significant change in antibody reduction if %PRA or cPRA were utilized as end points. However, 12 out of 15 (80%) patients that proceeded to transplant after desensitization had a significant decrease in antibody titers. Conclusions When reporting the effects of desensitization therapy, the use of %PRA and/or cPRA can be deceiving and can possibly result in the misinterpretation of the efficacy of protocols among different transplant centers. The utilization of titers was the most reliable way to proceed to transplant. Patients that were transplanted after the desensitization protocol (80%) have shown no significant difference from non- sensitized patients in antibody mediated rejection (p 0.05) and have not developed significant DSA after transplant.