Carrie A. Schinstock

The Banff 2015 Kidney Meeting Report: Current Challenges in Rejection Classification and Prospects for Adopting Molecular Pathology

The XIII Banff meeting, held in conjunction the Canadian Society of Transplantation in Vancouver, Canada, reviewed the clinical impact of updates of C4d‐negative antibody‐mediated rejection (ABMR) from the 2013 meeting, reports from active Banff Working Groups, the relationships of donor‐specific antibody tests (anti‐HLA and non‐HLA) with transplant histopathology, and questions of molecular transplant diagnostics. The use of transcriptome gene sets, their resultant diagnostic classifiers, or common key genes to supplement the diagnosis and classification of rejection requires further consensus agreement and validation in biopsies. Newly introduced concepts include the i‐IFTA score, comprising inflammation within areas of fibrosis and atrophy and acceptance of transplant arteriolopathy within the descriptions of chronic active T cell–mediated rejection (TCMR) or chronic ABMR. The pattern of mixed TCMR and ABMR was increasingly recognized. This report also includes improved definitions of TCMR and ABMR in pancreas transplants with specification of vascular lesions and prospects for defining a vascularized composite allograft rejection classification. The goal of the Banff process is ongoing integration of advances in histologic, serologic, and molecular diagnostic techniques to produce a consensus‐based reporting system that offers precise composite scores, accurate routine diagnostics, and applicability to next‐generation clinical trials.

Positive Crossmatch Kidney Transplant Recipients Treated With Eculizumab: Outcomes Beyond 1 Year

This study examined outcomes beyond 1 year in eculizumab‐treated (EC) positive crossmatch kidney transplants (+XMKTx) compared to a historical control group. +XMKTx received desensitization with either plasma exchange (PE) alone (N = 48) or PE and EC (N = 30). EC, given for at least 1 month, was continued in the setting of persistently high DSA (B flow cytometric crossmatch [BFXM] >200) including: 4 weeks (n = 14); 9 weeks (n = 6), 6 months (n = 2), and 12 months (n = 8). All patients had at least 2 years follow‐up. The incidence of acute clinical ABMR was lower in the EC group than controls (6.7% vs. 43.8% p < 0.01). Death‐censored allograft survival was similar between groups. Chronic ABMR was the main cause of graft loss. On 1‐year protocol biopsies, no differences were noted between EC and controls including: cg score >0, 26.7% versus 31.9% (p = 0.62), ptc score ≥ 2, 60.0% versus 60.0% (p = 1.00), or C4d + , 33.8% versus 13.5% (p = 0.08). A persistently high BFXM in EC‐treated patients was associated with cg score >0 at 1 year, while EC appeared to protect against cg if the BFXM remained low. We conclude that despite decreasing acute clinical ABMR rates, EC treatment does not prevent chronic ABMR in recipients with persistently high BFXM after +XMKTx.

Positive crossmatch kidney transplant recipients treated with eculizumab

This study examined outcomes beyond 1 year in eculizumab‐treated (EC) positive crossmatch kidney transplants (+XMKTx) compared to a historical control group. +XMKTx received desensitization with either plasma exchange (PE) alone (N = 48) or PE and EC (N = 30). EC, given for at least 1 month, was continued in the setting of persistently high DSA (B flow cytometric crossmatch [BFXM] >200) including: 4 weeks (n = 14); 9 weeks (n = 6), 6 months (n = 2), and 12 months (n = 8). All patients had at least 2 years follow‐up. The incidence of acute clinical ABMR was lower in the EC group than controls (6.7% vs. 43.8% p < 0.01). Death‐censored allograft survival was similar between groups. Chronic ABMR was the main cause of graft loss. On 1‐year protocol biopsies, no differences were noted between EC and controls including: cg score >0, 26.7% versus 31.9% (p = 0.62), ptc score ≥ 2, 60.0% versus 60.0% (p = 1.00), or C4d + , 33.8% versus 13.5% (p = 0.08). A persistently high BFXM in EC‐treated patients was associated with cg score >0 at 1 year, while EC appeared to protect against cg if the BFXM remained low. We conclude that despite decreasing acute clinical ABMR rates, EC treatment does not prevent chronic ABMR in recipients with persistently high BFXM after +XMKTx.

Urinalysis is more specific and urinary neutrophil gelatinase-associated lipocalin is more sensitive for early detection of acute kidney injury.

BACKGROUND Neutrophil gelatinase-associated lipocalin (NGAL) protein is a promising biomarker to detect acute kidney injury (AKI). Earlier detection of AKI could facilitate evaluation of novel therapeutic strategies. METHODS Random and 24-h urine samples were prospectively obtained from 125 normal volunteers for analytic validation of a urinary enzyme-linked immunosorbent assay for NGAL. For clinical validation of the test, urine from 363 emergency department patients admitted to the hospital was obtained for NGAL enzyme-linked immunosorbent assay and urinalysis and AKI was determined by the use of Acute Kidney Injury Network (AKIN) criteria. RESULTS NGAL was stable in urine for 7 days when ambient, 4 °C or frozen (-20 or -70 °C). The assay was linear between 0.24 and 10,000 ng/mL with a limit of quantitation of 0.24 ng/mL. Intra- and inter-assay precision were excellent (coefficient of variation <5%); however, urinary white blood cells were associated with increased NGAL levels. The 95th percentile reference value for NGAL in females is ≤ 65.0 and ≤ 23.4 ng/mL in males. Urinary NGAL levels increased with AKI stage but had only fair sensitivity (65%) and specificity (65%) to differentiate no AKI versus Stages 1, 2 or 3 (area under the curve 0.70). Urinalysis with microscopy was very specific (91%) but not very sensitive (22%) with an area under the curve of 0.57. CONCLUSIONS NGAL can be reliably measured in clinical urine samples, although pyuria is an important potential confounder. In our cohort, increased urinary NGAL was associated with AKI by the AKIN criteria; however, the sensitivity and specificity were only fair, in part because patients with pre-renal causes are not excluded by AKIN criteria. Conversely, findings on microscopic urinalysis are very specific for AKI.

Discordance Between Iothalamate and Iohexol Urinary Clearances

BACKGROUND Iothalamate and iohexol are contrast agents that have supplanted inulin for the measurement of glomerular filtration rate (GFR) in clinical practice. Previous studies have noted possible differences in renal handling of these 2 agents, but clarity about the differences has been lacking. STUDY DESIGN Study of diagnostic test accuracy. SETTING & PARTICIPANTS 150 participants with a wide range of GFRs were studied in an outpatient clinical laboratory facility. INDEX TESTS Simultaneous urinary clearances of iothalamate, iohexol, and creatinine. REFERENCE TEST None. OUTCOME Relative differences between the urinary clearances. Iohexol and iothalamate in plasma and urine were assayed concurrently by a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. RESULTS Mean iohexol, iothalamate, and creatinine clearances were 52±28 (SD), 60±34, and 74±40 mL/min/1.73 m(2), respectively. The proportional bias of iohexol to iothalamate urinary clearance was 0.85 (95% CI, 0.83-0.88) and was proportional across the GFR range. The mean proportional bias of iohexol clearance compared with creatinine clearance is 1.27 (95% CI, 1.20-1.34), whereas that of iothalamate clearance compared with creatinine clearance is 1.09 (95% CI, 1.03-1.15). LIMITATIONS Lack of reference standard. CONCLUSIONS This study reveals a significant and consistent difference between urinary clearances of iothalamate and iohexol. Comparison of studies reporting renal clearance measurements using iohexol versus iothalamate must account for this observed bias.

Changing Kidney Allograft Histology Early Posttransplant: Prognostic Implications of 1-Year Protocol Biopsies

Allograft histology 1 year posttransplant is an independent correlate to long‐term death‐censored graft survival. We assessed prognostic implications of changes in histology first 2 years posttransplant in 938 first kidney recipients, transplanted 1999–2010, followed for 93.4 ± 37.7 months. Compared to implantation biopsies, histology changed posttransplant showing at 1 year that 72.6% of grafts had minor abnormalities (favorable histology), 20.2% unfavorable histology, and 7.2% glomerulonephritis. Compared to favorable, graft survival was reduced in recipients with unfavorable histology (hazards ratio [HR] = 4.79 [3.27–7.00], p < 0.0001) or glomerulonephritis (HR = 5.91 [3.17–11.0], p < 0.0001). Compared to unfavorable, in grafts with favorable histology, failure was most commonly due to death (42% vs. 70%, p < 0.0001) and less commonly due to alloimmune causes (27% vs. 10%, p < 0.0001). In 80% of cases, favorable histology persisted at 2 years. However, de novo 2‐year unfavorable histology (15.3%) or glomerulonephritis (4.7%) related to reduced survival. The proportion of favorable grafts increased during this period (odds ratio = 0.920 [0.871–0.972], p = 0.003, per year) related to fewer DGF, rejections, polyoma‐associated nephropathy (PVAN), and better function. Graft survival also improved (HR = 0.718 [0.550–0.937], p = 0.015) related to better histology and function. Evolution of graft histologic early posttransplant relate to long‐term survival. Avoiding risk factors associated with unfavorable histology relates to improved histology and graft survival.

The Value of Protocol Biopsies to Identify Patients with De Novo Donor Specific Antibody at High Risk for Allograft Loss

De novo donor-specific antibody (dnDSA) is associated with antibody-mediated rejection (AMR) and allograft loss, yet the allograft histology associated with dnDSA remains unclear. The aim of this study was to examine the allograft histology associated with dnDSA in patients with serial surveillance biopsies. We retrospectively studied adult conventional solitary kidney transplant recipients from October 2007 to May 2014. The definition of dnDSA was new donor-specific antibody (DSA) with mean fluorescence intensity (MFI) >1000. The incidence of dnDSA was 7.0% (54 of 771) over mean follow-up of 4.2 ± 1.9 years. Patients with dnDSA had reduced death-censored allograft survival (87.0% vs. 97.0% no dnDSA, p < 0.01). Moreover, 94% of patients received a biopsy after dnDSA (mean of three biopsies per patient). AMR was present in 25.0% and 52.9% of patients at dnDSA detection and at 1 year, respectively. Patients with both class I and II dnDSA had the highest rate of allograft loss. The higher the sum MFI at dnDSA detection, the higher the incidence of AMR. In conclusion, patients with dnDSA without AMR at time of detection may benefit from a follow-up biopsy within 1 year because AMR can be missed initially. In addition, the dnDSA class and sum MFI at baseline appear to be prognostic. The higher the sum MFI of dnDSA at baseline, the higher the incidence of AMR.

Intravitreal Antivascular Endothelial Growth Factor Therapy May Induce Proteinuria and Antibody Mediated Injury in Renal Allografts.

Introduction Systemic adverse effects of intravenous antivascular endothelial growth factor (VEGF) therapy include: hypertension, proteinuria, renal failure, and thrombotic microangiopathy. Intravitreal therapy with these agents is generally believed to be safe. Methods We report 2 cases of renal transplant recipients who developed significant allograft dysfunction after the initiation of intravitreal anti-VEGF therapy. Results The first case is a 67-year-old man with polycystic kidney disease and recipient of a zero-antigen mismatch kidney allograft which developed worsening proteinuria over the first year after transplantation. At 4 months, a biopsy showed only minimal fibrosis and atrophy. At 1 year, an allograft biopsy showed phospholipase A 2 receptor–negative membranous nephropathy. The second patient was a 52-year-old man with tuberous sclerosis who was a recipient of a living related kidney allograft with diminished but stable graft function 16 years from transplantation. After the initiation of intravitreal anti-VEGF therapy, there was an escalating degree of proteinuria. Renal biopsy revealed acute and chronic antibody-mediated rejection with glomerular thrombi and transplant glomerulopathy. Conclusions These cases, although do not prove causality, point to the need for careful follow-up of renal transplant recipients undergoing intravitreal therapy with anti-VEGF agents. These locally administered agents may play a role in the development of proteinuria and modulate antibody-mediated phenomena. We recommend that in renal transplant recipients undergoing therapy with intravitreal anti-VEGF agents, proteinuria be checked monthly, and there should be a low threshold for performing a biopsy to evaluate for allograft injury.

32 Doses of Bortezomib for Desensitization Is Not Well Tolerated and Is Associated With Only Modest Reductions in Anti-hla Antibody

Background We previously showed that bortezomib (BTZ) partially depletes plasma cells, yet has limited efficacy for desensitization in kidney transplant candidates when up to 16 doses is given. Methods This study aimed to determine the safety and efficacy of 32 doses of BTZ (1.3 mg/m2 of body surface area) in 10 highly sensitized kidney transplant candidates with alloantibodies against their intended living donor. Results Dose reduction was needed in 2 patients and 2 others completely discontinued therapy for adverse events. Anti-HLA antibodies mean fluorescence intensity (MFI) values were stable prior to BTZ (P = 0.96) but decreased after therapy (mean decrease of 1916 [SE, 425] MFI, P < 0.01). No patient developed a negative crossmatch against their original intended donor, and the calculated panel-reactive antibodies based on MFI of 2000, 4000, and 8000 was unchanged in all patients. Conclusions These data suggest that 32 doses of BTZ monotherapy was not well tolerated and resulted in only a modest reduction in anti-HLA antibodies.

Interpreting Anti-HLA Antibody Testing Data: A Practical Guide for Physicians.

Abstract The development of sensitive methods for alloantibody detection has been a significant advance in clinical transplantation. However, the complexity of the data from solid phase and crossmatch assays has led to potential confusion about how to use the results for clinical decision making. The goal of this review is to provide a practical guide for transplant physicians for the interpretation of antibody data to supplement consultation with local tissue typing experts. Sources of variability in both the solid phase and crossmatch assay are discussed as are recent data regarding C1q binding antibodies and IgG subclass testing. Although definitive approaches to alloantibody testing are not possible with our current knowledge, we outline a pragmatic approach that we hope will enhance clinical management in this area.