Posttransplant Outcomes for cPRA-100% Recipients Under the New Kidney Allocation System.

BACKGROUND: There is concern in the transplant community that outcomes for the most highly sensitized recipients might be poor under Kidney Allocation System (KAS) high prioritization. METHODS: To study this, we compared posttransplant outcomes of 525 pre-KAS (December 4, 2009, to December 3, 2014) calculated panel-reactive antibodies (cPRA)-100% recipients to 3026 post-KAS (December 4, 2014, to December 3, 2017) cPRA-100% recipients using SRTR data. We compared mortality and death-censored graft survival using Cox regression, acute rejection, and delayed graft function (DGF) using logistic regression, and length of stay (LOS) using negative binomial regression. RESULTS: Compared with pre-KAS recipients, post-KAS recipients were allocated kidneys with lower Kidney Donor Profile Index (median 30% versus 35%, P < 0.001) but longer cold ischemic time (CIT) (median 21.0 h versus 18.6 h, P < 0.001). Compared with pre-KAS cPRA-100% recipients, those post-KAS had higher 3-year patient survival (93.6% versus 91.4%, P = 0.04) and 3-year death-censored graft survival (93.7% versus 90.6%, P = 0.005). The incidence of DGF (29.3% versus 29.2%, P = 0.9), acute rejection (11.2% versus 11.7%, P = 0.8), and median LOS (5 d versus 5d, P = 0.2) were similar between pre-KAS and post-KAS recipients. After accounting for secular trends and adjusting for recipient characteristics, post-KAS recipients had no difference in mortality (adjusted hazard ratio [aHR]: 0.861.623.06, P = 0.1), death-censored graft failure (aHR: 0.521.001.91, P > 0.9), DGF (adjusted odds ratio [aOR]: 0.580.861.27, P = 0.4), acute rejection (aOR: 0.610.941.43, P = 0.8), and LOS (adjusted LOS ratio: 0.981.161.36, P = 0.08). CONCLUSIONS: We did not find any statistically significant worsening of outcomes for cPRA-100% recipients under KAS, although longer-term monitoring of posttransplant mortality is warranted.

Proposal for the International Society for Cell & Gene Therapy position statement on assays for the quality control and potency assessment of adoptive cellular immunotherapies.

Translation of cell and gene therapies from pre-clinical experiments to clinical trials and final drug licensing brings requires the development, verification and even validation of the assays essential for the definition of the drug product. The technical and scientific challenges in doing this are far greater than they seem at first and are compounded by a lack of approved standards for assays used to support (c)GMP manufacture. This paper highlights some of those challenges and proposes solutions based on the experience of our colleagues using similar assay platforms in regulated pathology laboratories.

Performance Characteristics and Validation of Next-Generation Sequencing for Human Leucocyte Antigen Typing.

High-resolution human leukocyte antigen (HLA) matching reduces graft-versus-host disease and improves overall patient survival after hematopoietic stem cell transplant. Sanger sequencing has been the gold standard for HLA typing since 1996. However, given the increasing number of new HLA alleles identified and the complexity of the HLA genes, clinical HLA typing by Sanger sequencing requires several rounds of additional testing to provide allele-level resolution. Although next-generation sequencing (NGS) is routinely used in molecular genetics, few clinical HLA laboratories use the technology. The performance characteristics of NGS HLA typing using TruSight HLA were determined using Sanger sequencing as the reference method. In total, 211 samples were analyzed with an overall accuracy of 99.8% (2954/2961) and 46 samples were analyzed for precision with 100% (368/368) reproducibility. Most discordant alleles were because of technical error rather than assay performance. More important, the ambiguity rate was 3.5% (103/2961). Seventy-four percentage of the ambiguities were within the DRB1 and DRB4 loci. HLA typing by NGS saves approximately $6000 per run when compared to Sanger sequencing. Thus, TruSight HLA assay enables high-throughput HLA typing with an accuracy, precision, ambiguity rate, and cost savings that should facilitate adoption of NGS technology in clinical HLA laboratories.

Recommendations for donor human leukocyte antigen assessment and matching for allogeneic stem cell transplantation: consensus opinion of the Blood and Marrow Transplant Clinical Trials Network (BMT CTN).

The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) conducts large, multi-institutional clinical trials with the goal of improving the outcomes of hematopoietic cell transplantation (HCT) for patients with life-threatening disorders. Well-designed HCT trials benefit from standardized criteria for defining diagnoses, treatment plans, and graft source selection. In this perspective, we summarize evidence supporting criteria for the selection of related and unrelated adult volunteer progenitor cell donors or umbilical cord blood units. These standardized criteria for graft source selection have been adopted by the BMT CTN to enhance the interpretation of clinical findings within and among future clinical protocols.

External quality assessment of patient HLA-B*57:01 testing prior to abacavir prescription.

Hypersensitivity reactions to the drug abacavir are strongly associated with possession of HLA-B*57:01. Hence, patients with HIV/AIDS who may be prescribed abacavir should be tested for this HLA allele and the drug withheld from those that possess B*57:01. The UK National External Quality Assessment Service for Histocompatibility and Immunogenetics has operated a scheme for B*57:01 testing since 2008 which, in 2013, involved 47 participants from 12 countries. A total of 24 B*57:01-positive, 2 B*57:03-positive and 22 B*57-negative blood samples (including 2 B*58 samples) were distributed to between 28 and 47 laboratories each year over 6 years. Participants, who were unaware of the samples' HLA types, tested and reported on their B*57/B*57:01 status. A total of 1868 reports were assessed over the 6 years. Of the 880 reports on B*57:01 samples, 93.4% were correctly assigned as B*57:01, 2.8% were assigned as groups of B*57 alleles including B*57:01, and 3.3% were reported as B*57 positive only. Over the 6 years, there were four (0.46%) false B*57:01 negative reports. All the B*57:03-positive and B*57-negative samples, involving 72 and 916 assignments, respectively, were essentially reported as B*57:01 negative. Thus, there were no false B57:01 positive assignments. The reporting of B*57:01 status over the last 3 years of the scheme was 99.8% sensitive and 100% specific. Over the last year, it was 100% sensitive and 100% specific.

Comprehensive assessment and standardization of solid phase multiplex-bead arrays for the detection of antibodies to HLA.

Solid phase multiplex-bead arrays for the detection and characterization of HLA antibodies provide increased sensitivity and specificity compared to conventional lymphocyte-based assays. Assay variability due to inconsistencies in commercial kits and differences in standard operating procedures (SOP) hamper comparison of results between laboratories. The Clinical Trials in Organ Transplantation Antibody Core Laboratories investigated sources of assay variation and determined if reproducibility improved through utilization of SOP, common reagents and normalization algorithms. Ten commercial kits from two manufacturers were assessed in each of seven laboratories using 20 HLA reference sera. Implementation of a standardized (vs. a nonstandardized) operating procedure greatly reduced MFI variation from 62% to 25%. Although laboratory agreements exceeded 90% (R(2) ), small systematic differences were observed suggesting center specific factors still contribute to variation. MFI varied according to manufacturer, kit, bead type and lot. ROC analyses showed excellent consistency in antibody assignments between manufacturers (AUC > 0.9) and suggested optimal cutoffs from 1000 to 1500 MFI. Global normalization further reduced MFI variation to levels near 20%. Standardization and normalization of solid phase HLA antibody tests will enable comparison of data across laboratories for clinical trials and diagnostic testing.

EpHLA software: a timesaving and accurate tool for improving identification of acceptable mismatches for clinical purposes.

UNLABELLED: The HLAMatchmaker algorithm, which allows the identification of "safe" acceptable mismatches (AMMs) for recipients of solid organ and cell allografts, is rarely used in part due to the difficulty in using it in the current Excel format. The automation of this algorithm may universalize its use to benefit the allocation of allografts. Recently, we have developed a new software called EpHLA, which is the first computer program automating the use of the HLAMatchmaker algorithm. Herein, we present the experimental validation of the EpHLA program by showing the time efficiency and the quality of operation. The same results, obtained by a single antigen bead assay with sera from 10 sensitized patients waiting for kidney transplants, were analyzed either by conventional HLAMatchmaker or by automated EpHLA method. Users testing these two methods were asked to record: (i) time required for completion of the analysis (in minutes); (ii) number of eplets obtained for class I and class II HLA molecules; (iii) categorization of eplets as reactive or non-reactive based on the MFI cutoff value; and (iv) determination of AMMs based on eplets' reactivities. We showed that although both methods had similar accuracy, the automated EpHLA method was over 8 times faster in comparison to the conventional HLAMatchmaker method. In particular the EpHLA software was faster and more reliable but equally accurate as the conventional method to define AMMs for allografts. CONCLUSION: The EpHLA software is an accurate and quick method for the identification of AMMs and thus it may be a very useful tool in the decision-making process of organ allocation for highly sensitized patients as well as in many other applications.

Frequency and targeted detection of HLA-DPB1 T cell epitope disparities relevant in unrelated hematopoietic stem cell transplantation.

The majority of unrelated donor (UD) hematopoietic stem cell (HSC) transplants are performed across HLA-DP mismatches, which, if involving disparity in a host-versus-graft (HVG) direction for an alloreactive T cell epitope (TCE), have been shown by our group to be associated with poor clinical outcome in 2 cohorts of patients transplanted for hematopoietic malignancies and beta-thalassemia, respectively. Using site-directed mutagenesis of DPB1*0901, we show here that the TCE is abrogated by the presence of amino acids LFQG in positions 8-11 of the DP beta-chain. Based on this and on alloreactive T cell responsiveness, we have determined the presence or absence of the TCE for 72 DPB1 alleles reported in the ethnic groups representative of the worldwide UD registries, and predict that 67%-87% (mean 77%) of UD recipient pairs will not present a DPB1 TCE disparity in the HVG direction. We developed and validated in 112 healthy Italian blood donors an innovative approach of DPB1 epitope-specific typing (EST), based on 2 PCR reactions. Our data show that DPB1 TCE disparities may hamper the clinical success of a considerable number of transplants when DPB1 matching is not included into the donor selection criteria, and that a donor without DPB1 TCE disparities in the HVG direction can be found for the majority of patients. Moreover, the study describes the first protocol of targeted epitope-specific DPB1 donor-recipient matching for unrelated HSC transplantation. This protocol will facilitate large-scale retrospective clinical studies warranted to more precisely determine the clinical relevance of DPB1 TCE disparities in different transplant conditions.

Kidney and pancreas transplantation without a crossmatch in select circumstances--it can be done.

Given the constant flux in caseload and the number of personnel available in the OR, waiting for a final XM often prolongs organ preservation time (a room available at the time a XM is started is not available when the XM is completed). Longer preservation is associated with increased DGF and decreased graft survival. We have shown in a retrospective analysis that final XMs on 0% PRA recipients were always negative (Transplantation, 1999). We now describe a policy of: a) not doing screening XM and b) proceeding to the OR without a XM, in situations where the recipients's PRA has been documented to be 0% and when there have not been any interim transfusions (and the OR is ready before XM completion). Final XM is completed after the transplant. All patients send sera every 6 weeks for PRA (antiglobulin technique). If > o r=3 consecutive PRAs are 0%, no donor-specific screening XM is done prior to calling the patient in for tx (UNOS allocation algorithm used). If there have not been any interim transfusions, we have proceeded to tx prior to completion of the final XM. Between 1/1/98-12/31/99, we did 109 CAD kidney (K) and 79 simultaneous kidney pancreas (SPK) tx; 67 (61%) K and 56 (71%) SPK had 0% PRA. Of the 0% PRA, 25/67 (37%) K and 28/56 (50%) SPK had no pre-tx XM. For K with no XM, cold ischemia was shorter (13.2+/-0.2 vs. 18+/-0.9 hrs, p=0.01) and DGF less (12% vs. 24%, p=0.3); for SPK with no XM, cold ischemia was shorter (15.2+/-2 vs. 18+/-0.9 hrs, p=0.1); no diff in DGF. All post-XM were negative and there were no hyperacute rejections; there was no diff in acute rejection episodes. Actuarial 1 yr graft survival: no XM-K=87.5%, SKP=82%; Yes XM-K=88%, SKP=86% (NS). Our data suggests it is safe, in select circumstances, to proceed to the OR without a XM. Elimination of the screening XM for 0% PRA candidates saves money. Proceeding of the OR (if available) without a final XM shortens cold ischemia time.

Disproportionate HLA matching may contribute to racial disparity in patient survival following cardiac transplantation.

The purpose of this study is to investigate the impact of recipient race as well as HLA matching upon long-term survival following heart transplantation (HTx). The study also determines whether the degree of HLA matching between Caucasians and African Americans differs. This study was a retrospective analysis of 336 males (77% Caucasians and 23% African Americans) transplanted between 1983 and 1994, all having received cyclosporine-based immunosuppression. The results showed African Americans were transplanted at a significantly younger age than Caucasians (39.1 +/- 11.2 vs. 48.2 +/- 10 yr). The composition of end stage cardiac disease was startlingly different. Caucasians demonstrated 62% CAD, 31% IDCM and 7% other, whereas African Americans exhibited 24% CAD, 69% IDCM and 7% other. The ten-year survival rate for African American male recipients was inferior to Caucasian males. Survival at 1, 3, 5, 7 and 9 yr was 83%, 73%, 63%, 51%, 46% for Caucasians and 70%, 58%, 51%, 38% and 32% for African Americans. Furthermore, African Americans received more poorly matched organs compared to Caucasians. Among Caucasians for Class I, 46%, 53% and 1% received poor, moderate and well matched hearts, respectively. In contrast, African American were allocated 65%, 33% and 0% of poor, moderate, or well matched hearts. An analysis of Class II data revealed the same pattern (63%, 35% 2% of Caucasians and 78%, 18%, and 4% of African Americans received poor, moderate or well matched hearts). Survival for Caucasians improved when moderately versus poorly matched for Class I. Class II matching did not have an effect. African Americans showed a similar trend, although statistical significance was not reached. When comparing equivalent degrees of matching, African Americans had inferior survival rate when poorly matched for Class I relative to Caucasians. No statistical difference was observed for moderate matched Class I or for Class II analysis.