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2016 American Transplant Congress (ATC)

June 11-15, 2016 in Boston, MA


Abstracts


Sunday June 12, 2016


1/ Complement-Bindin Donor-Specific Anti-HLA Antibodies Are Associated with Severe Kidney Allograft Arteriosclerosis.

Concurrent Session: Novel Markers of Long Term Kidney Transplant Outcomes (2:30 PM-4:00 PM)

Ballroom A - 2:30 pm

A. Loupy, D. Viglietti, J. Duong Van Huyen, D. Glotz, C. Legendre, A. Zeevi, C. Lefaucheur. Necker Hospital, Paris, France; Saint-Louis Hospital, Paris, France; University of Pittsburgh Medical Center, Pittsburgh

The role of circulating donor-specific anti-HLA antibodies (DSA) in the development of accelerated arteriosclerosis have been recently reported in kidney transplant recipients. This study investigated the characteristics of DSA that are associated with the severity of allograft arteriosclerosis.

We enrolled 744 consecutive kidney transplantation performed between January 1, 2004 and January 1, 2010 at Necker Hospital (Paris, France), with systematic assessment of injury phenotype and arteriosclerotic lesions using the vascular fibrous intimal thickening (cv) Banff score on allograft biopsies performed at one year after transplantation. We assessed circulating DSA and their characteristics (specificity, HLA class, mean fluorescence intensity [MFI] and C1q-binding) at six months after transplantation.

We identified 281 patients with cv0 score, 213 patients with cv1 score, 189 patients with cv2 score and 61 patients with cv3 score. The distribution of DSA according to cv score was the following: 47/281 (17%) in cv0 patients, 39/213 (18%) in cv1 patients, 63/189 (33%) in cv2 patients and 28/61 (46%) in cv3 patients. Immunodominant DSA (iDSA) MFI level was positively correlated with the severity of arteriosclerosis (Spearman's rho=0.23, p=0.002), with a mean MFI of 3204.0±3725.2 in cv0 patients, 3760±3598 in cv1 patients, 4892±4676 in cv2 patients and 5541±3892 in cv3 patients. C1q-binding DSA prevalence increased with the severity of allograft arteriosclerosis: 8/281 (3%) in cv0 patients, 6/213 (3%) in cv1 patients, 25/189 (13%) in cv2 patients and 9/61 (15%) in cv3 patients (p<0.001). Patients with C1q-binding iDSA had a higher cv score compared with patients with non-C1q-binding DSA (1.7±1.0 versus 1.3±1.1, respectively, p=0.01). The C1q-binding capacity of DSA was associated with increased microvascular inflammation (p<0.001) and C4d deposition in peritubular capillaries or arteries (p<0.001).

This study shows a biological gradient between DSA MFI level and the severity of allograft arteriosclerosis. The complement-binding capacity of DSA is associated with an increased severity of arteriosclerosis and complement deposition in allograft.


Monday June 13, 2016



2/ A New Diagnostic Score for Microvascular Inflammation in Antibody-Mediated Rejection in Heart Transplantation.

Concurrent Session: Molecular and Bio-Markers in Hearts and VADs - A New Hope (2:30 PM-4:00 PM)

Room 102 - 3:18 pm

M. Racapé, A. Loupy, R. Guillemain, A. François, P. Rouvier, C. Toquet, X. Jouven, J. Venner, L. Hidalgo, J. Reeve, P. Bruneval, J. Duong Van Huyen, P. Halloran. European Georges Pompidou Hospital, Paris, France; Necker Hospital, Paris, France; Rouen University Hospital, Rouen, France; La Pitié Salpêtrière Hospital, Paris, France; Laennec Hospital, Nantes, France; University of Alberta, Edmonton, Canada

Background

The ISHLT working formulation defines Intravascular Activated Mononuclear Cells (IAMC) as one of the histopathologic features of antibody-mediated rejection (ABMR) in heart transplantation. However, no accurate grading of IAMC correlating with pAMR diagnosis has been proposed. The aim of this study was to develop a score to grade the extent and the pattern of the IAMC in endomyocardial biopsies (EMB) with ABMR.

Methods

This case control study included heart transplant patients from five French referral centers with biopsy-proven ABMR (pAMR1-3) (n=64) and a matched control group of 44 patients without rejection (pAMR0). IAMC on EMBs was graded blind of pAMR grades by two skilled pathologists according to the percentage of the area with microvascular inflammation in capillaries and to the maximum number of IAMC in the most affected capillary on a 0 to 3 scale and a positivity defined by a grade ≥ 1. The score was compared to the gene expression profiling in EMBs by microarray using pathogenesis-based transcripts reflecting endothelial activation (ENDAT), DSA (DSAST), macrophage burden (QCMAT), gamma-interferon response (GRIT), T-cell (TCB) and NK-cell burden (NKB) (http://atagc.med.ualberta.ca).

Results

100% of control EMBs were graded as IAMC score 0. All pAMR1(I+) EMBs and none of the pAMR1(H+) and pAMR2-3 were graded as IAMC score 0. The highest IAMC score 3 was mainly distributed in pAMR2-3 (Fischer's exact=0.000). Increase in the IAMC score was associated with an increase in the proportion of C4d positive EMBs (scores ≥1) and of EMBs positive for macrophage markers, and a higher proportion of DSA positive at EMB. It was also associated with an increase in the expression of ENDAT, DSAST, GRIT, NKB, TCB and QCMAT transcripts (All Kruskal-Wallis p<0.001).

Conclusion

The IAMC score is correlated with molecular activation in grafted myocardial tissue. The IAMC score could help pathologists for ABMR diagnosis, emphasizing the value of the microvascular inflammation.



3/ Donor-Specific Antibody Is a Major Independent Predictor of Accelerated Heart Allograft Vasculopathy (CAV).

Concurrent Session: Molecular and Bio-Markers in Hearts and VADs - A New Hope (2:30 PM-4:00 PM)

Room 102 - 3:30 pm

M. Bories, S. Varnous, C. Lefaucheur, P. Rouvier, R. Guillemain, P. Bruneval, J. Duong Van Huyen, A. Loupy. European Georges Pompidou Hospital, Paris, France; La Pitié Salpêtrière Hospital, Paris, France; Saint-Louis Hospital, Paris, France; Necker Hospital, Paris, France

Introduction

The role of circulating DSA in addition to traditional cardiovascular risk factors, in the development of accelerated CAV have not been demonstrated. We investigated the role of circulating DSA in the development of accelerated CAV in a large prospective observational cohort of heart transplant recipients.

Methods

This was an observational prospective cohort study, including 723 heart transplant patients from 2 centers between 2004 and 2011. Participants were screened for traditional cardiovascular risk factors, circulating anti-HLA antibodies, and their properties (specificity, HLA class, strength). All patients underwent prospective heart allograft biopsies and angiogram with assessment of CAV lesions. We assessed the independent determinants of CAV at 3 years after transplantation.

Results

A total of 145 patients (20.1%) had circulating DSA at the day of transplantation. 170 patients (23.5%) experienced acute rejection in the first 3 years post-transplant with 128 cases (17.7%) of grade 2R ACR and 83 cases (11.5%) of antibody-mediated rejection (ISHLT pAMR+). At 3 years post transplant 29.7% of patients had CAV (20.8%, 7.4% and 1.5% with CAV scores of 1, 2 and 3 respectively). After adjusting on traditional risk factors (recipient age, primary heart disease, gender, hypertension, tobacco use, dyslipidemia, diabetes mellitus, BMI), donor factors (age, gender, BMI, cause of death), transplant characteristics (cold ischemia time, center, emergency heart transplantation), immunological parameters (circulating DSA at the day of transplantation and acute rejection post transplant), and CMV disease occurence post-transplant, the independent determinants of CAV at 3 years were: donor age (RR=1.05; 95%CI=1.03-1.08), recipient dyslipidemia (RR=2.1; 95%CI= 1.02-4.29), presence of circulating DSA at the day of transplantation (RR=2.45 95%CI=1.45-4.12). Occurrence of pAMR2 post-transplant was also a strong and independent factor associated with CAV at 3 years post-transplant (RR=3.51, IC95%=1.84-6.69). This group showed decreased patient survival (HR=1.8 p=0.01).

Conclusion

Circulating DSA are major determinants of severe arteriosclerosis, independent of traditional cardiovascular risk factors. Antibody-mediated CAV is associated with reduced patient survival.


4/ Effect of Complement Inhibition Therapy (Eculizumab) in Patients with C1q-Binding Donor-Specific Anti-HLA Antibodies: A Molecular Appraisal.

Concurrent Session: Identifying Antibodies - Tools of the Trade (2:30 PM-4:00 PM)

Ballroom B - 3:30 pm

C. Lefaucheur, L. Hidalgo, J. Reeve, D. Viglietti, C. Gosset, O. Aubert, C. Ulloa, C. Legendre, D. Glotz, P. Halloran, A. Loupy. Saint-Louis Hospital, Paris, France; University of Alberta, Edmonton, Canada; Necker Hospital, Paris, France

Complement-binding anti-HLA DSA have demonstrated higher rejection rate and decreased allograft outcome. We investigated the effect of terminal complement inhibition (Eculizumab) in a cohort of patients with C1q-binding DSA at the time of transplantation.

We enrolled 2 groups of patients, all with C1q-binding DSA at the time of transplantation between 2011 and 2013: i) 12 patients (study group) received Eculizumab in the prevention of AMR according to a phase 2 clinical trial (NCT01567085); ii) A matched control group of 12 patients receiving standard of care (PP x4 and IVIG 2g/kg BW). Surveillance kidney allograft biopsies were performed at 14 days and 12 months post-transplant in all patients. In both groups the allograft injury phenotype was assessed by histopathology and gene expression. DSA characteristics, GFR and proteinuria were also determined at those time points.

Baseline characteristics were similar in both groups in term of donor, recipient, transplant and DSA characteristics. At Day-14, patients receiving Eculizumab had lower histological Banff scores for peritubular capillaritis (p=0.0074), interstitial inflammation (p=0.0133) and tubulitis (p=0.0055). Molecular allograft gene expression revealed lower AMR activity reflected by decreased endothelial DSA-selective transcripts (DSAST, 3.97 fold-change, p<0.001) and ABMR Molecular Score (1.81 fold-change p=0.0061). This lower activity was related to lower expression of NK transcripts (NKb, 5.25 fold-change, p<0.0001), macrophage transcripts (QCMAT, 1.67 fold-change, p=0.04), IFNG production and inducing transcripts (GRIT, 2.65 fold-change, p<0.001) and acute kidney injury transcripts (IRRATS, 1.53 fold-change, p=0.01) as compared with patients receiving standard of care. At 1-year (after 9 months of treatment wash out), the histologic scores (g, ptc, cg, C4d, i, t, v, IFTA and cv) and molecular scores for ABMR, GRIT, QCMAT and IRRATS were similar in both groups with the exception of NKb (1.8 fold-change, p=0.02) and DSAST (2 fold-change, p=0.01). At 1 year, eGFR and DSAmax MFI were similar in both groups while there was a trend lo lower proteinuria among the Eculizumab treated group (p=0.0562).

Eculizumab prophylaxis in patients with C1q-binding DSA reduces early AMR activity with major effect on NK burden with limited effect after treatment discontinuation.



5/ Composite Score to Define the Risk of Allograft Loss After Standard-of-Care Treatment of Antibody-Mediated Rejection in Kidney Transplantation.

Concurrent Session: Identifying Antibodies - Tools of the Trade (2:30 PM-4:00 PM)

Ballroom B - 3:42 pm

D. Viglietti, A. Loupy, J. Duong Van Huyen, J. Verine, A. Zeevi, C. Legendre, D. Glotz, C. Lefaucheur. Saint-Louis Hospital, Paris, France; Necker Hospital, Paris, France; University of Pittsburgh Medical Center, Pittsburgh

The development of a reliable surrogate endpoint for allograft survival after AMR treatment is a current unmet need in clinical transplantation (FDA AMR Workshop). We investigated the clinical, histological and immunological determinants of allograft survival in patients with active AMR receiving standard-of-care treatment in a prospective observational study.

We prospectively enrolled consecutive kidney transplant recipients with biopsy-proven active AMR diagnosed between 2007 and 2013 in two Paris transplant centers. All study patients received standardized treatment including plasmaphereses (x4), high-dose intravenous immune globulins (2 g/kg) repeated every 3 weeks for 3 rounds and rituximab (375 mg per square meter of body-surface area). Patients were systematically assessed at the time of diagnosis and 3 months post-treatment for clinical data (eGFR and proteinuria), histological characteristics (allograft biopsy) and circulating anti-HLA DSA characteristics (specificity, HLA class, mean fluorescence intensity [MFI] and C1q-binding capacity).

We included 291 patients with biopsy-proven acute or chronic active AMR who received standard-of-care treatment. The 5-year allograft survival after AMR diagnosis was 69.5% (95% CI: 62.7-75.2). Post-treatment independent determinants of allograft loss included eGFR (HR=0.97, 95% CI: 0.96-0.98, p<0.001), microvascular inflammation (g+ptc) score (HR=1.2, 95% CI: 1.0-1.3, p=0.035), allograft glomerulopathy (cg) score (HR=1.4, 95% CI: 1.1-1.8, p=0.004) and complement-binding capacity of DSA (HR=5.2, 95% CI: 3.3-8.3, p<0.001). On the basis of these predictors, we built a composite risk score for allograft loss after AMR treatment that showed a good predictive capacity: c-statistic, 0.77 (1000 bootstrap 95% CI: 0.71-0.84). For centers that do not use C1q-binding assay, we replaced C1q-binding assessment by the MFI of the highest rank anti-HLA DSA. The predictive capacity of the MFI-based score was 0.74 (95% CI: 0.68-0.81).

A systematic clinical, histological and immunological evaluation of the response to treatment at 3-month post-AMR allows to identify patients at high risk of allograft loss. We defined a post-AMR treatment composite score with a good performance to predict allograft loss. Further studies should validate this score on different independent cohorts.



6/ Post-Transplant Monitoring of Donor-Specific Anti-HLA Antibodies and Their Characteristics Improves Risk Stratification of Kidney Allograft Loss.

Concurrent Session: Kidney Transplant Recipient: Long Term Outcomes Session I (4:30 PM-6:00 PM)

Veterans Auditorium - 4:42 pm

D. Viglietti, A. Loupy, C. Bentlejewski, C. Legendre, D. Glotz, A. Zeevi, C. Lefaucheur. Saint-Louis Hospital, Paris, France; Necker Hospital, Paris, France; University of Pittsburgh Medical Center, Pittsburgh

Circulating donor-specific anti-HLA antibodies (DSA) are associated with allograft failure in solid-organ transplantation. We investigated the pathogenic characteristics of DSA that may improve risk prediction of allograft loss in a population-based study.

We enrolled consecutive patients who received kidney allografts at two Paris centers between 2007 and 2010. Patients were screened for the presence of circulating DSA at the time of transplantation (day-0), at one year and two years after transplantation or during an episode of acute rejection in the first two years after transplantation. We assessed DSA characteristics, including specificity, HLA class, mean fluorescence intensity, C1q-binding capacity, and IgG subclasses at day-0 and at the time of first post-transplant detection.

Of the 858 patients included in the study 88 (10.3%) patients had day-0 DSA and 184 (21.6%) patients were identified with post-transplant DSA. When we considered all immunologic parameters at the time of transplantation, the detection of day-0 DSA was the strongest independent immunologic risk factor of allograft loss (HR=2.7, 95% CI: 1.6-4.6; p<0.001). The post-transplant independent immunologic determinants of allograft loss were the detection of C1q-binding DSA (HR=4.4, 95% CI: 2.2-8.8, p<0.001) and the detection of IgG3-positive DSA (HR=3.5, 95% CI: 1.6-7.4, p=0.001).

We built a multivariate model for allograft loss at the time of transplantation integrating donor age, donor type, cold ischemia time and day-0 DSA. This baseline model showed a moderate discrimination capacity (C-statistic of 0.66). The addition of post-transplant DSA increased significantly the performance of the baseline model (C-statistic of 0.71). The detection of C1q-binding DSA and IgG3-positive DSA further improved the risk prediction of allograft loss: C-statistic, 0.75 (1000 bootstrap mean difference: 0.029, 95% CI: 0.028-0.030) and 0.74 (1000 bootstrap mean difference: 0.022, 95% CI: 0.021-0.023), respectively, and integrated discrimination improvement, 0.07 (p<0.001) and 0.06 (p<0.001), respectively.

Post-transplant serial monitoring of DSA improves risk stratification of kidney allograft loss. The characterization of DSA by complement-binding capacity and IgG3 subclass further improves the performance to predict allograft loss beyond their simple detection.


7/ Phenotype and Outcome of Antibody-Mediated Rejection Due to Pre-Existing and De Novo DSA in Kidney Recipients.

Concurrent Session: Antibody Mediated Rejection in Kidney Transplantation: De Novo DSA (4:30 PM-6:00 PM)

Ballroom B - 4:54 pm

O. Aubert, A. Loupy, L. Hidalgo, J. Reeve, D. Glotz, C. Legendre, C. Lefaucheur, P. Halloran. Paris Research Center for Organ Transplantation, Paris, France; University of Alberta, Edmonton, Canada; ATAGC, Edmonton, Canada

Antibody-mediated rejection (ABMR) presents with either pre-existing or de novo DSA. The aim of the study was to compare the two ABMR phenotypes and their outcome. From a cohort of 965 kidney biopsies from two North American and five European centers, we selected all patients with ABMR. In 205 patients with ABMR, 101 (49%) had pre-existing DSA and 104 (51%) de novo DSA. The median time from transplantation to biopsy-proven ABMR (TxBx) was earlier with pre-existing DSA (2.8 months) compared to de novo DSA (3.9 years). There was no difference for the GFR: 39.3 mL/min/1.73m2 for pre-existing DSA vs 41.3 for de novo DSA (p=0.487) but the de novo DSA group had more proteinuria (1.5 vs. 0.5 g/g creatinine) (p<0.001). Kidney biopsies with pre-existing DSA presented with more glomerulitis (mean g score 1.73 vs. 1.05), less transplant glomerulopathy (0.48 vs. 1.27) but similar peritubular capillaritis and C4d deposition. ABMR with pre-existing DSA more often had Class I DSA (40% vs. 25%, p=0.018) but lower mean MFI (5096 vs. 8587, p=0.002). Using the gene expression assessment, ABMR with pre-existing DSA exhibited more injury-repair response associated transcripts (IRRATS) (p=0.008) but less Gamma interferon inducible transcripts (GRIT1), NK cell transcript burden (NKB) and T cell transcript burden (TCB) (p=0.018, p=0.010 and p<0.001). The two ABMR phenotypes exhibited similar endothelial cell-associated transcript (ENDAT) expression and ABMR scores. Kidney allograft survival at 4 and 8 years after rejection was superior in the pre-existing DSA phenotype (78% and 63%) compared to the de novo DSA phenotype (54% and 35%) (p<0.001). Using a random forest, the most important variables associated with graft survival were GFR, proteinuria, TxBx, and the ABMR phenotype. Thus early ABMR with pre-existing DSA is associated with better allograft survival compared to late ABMR with de novo DSA. Among the potential explanations for superior results with early ABMR with pre-existing DSA are the aggressive early detection and treatment protocols used for this phenotype.


Tuesday June 14, 2016



8/ C1-Inhibitor in Acute Antibody-Mediated Rejection Non-Responsive to Conventional Therapy in Kidney Transplant Recipients: A Pilot Study.

Concurrent Session: Kidney Immunosuppression: Novel Agents (2:30 PM-4:00 PM)

Veterans Auditorium - 4:42 pm

C. Lefaucheur, D. Viglietti, C. Gosset, A. Loupy, A. Zeevi, D. Glotz. Saint-Louis Hospital, Paris, France; Necker Hospital, Paris, France; University of Pittsburgh Medical Center, Pittsburgh

The use of complement inhibitors in the treatment of acute antibody-mediated rejection (AMR) has not been thoroughly evaluated. We performed a prospective, single-arm, pilot study to assess the efficacy and safety of C1-inhibitor (CI-INH) Berinert added to high-dose intravenous immunoglobulin (IVIG) for the treatment of acute AMR that is non-responsive to conventional therapy.

Kidney recipients with acute AMR that was non-responsive to conventional standardized treatment (plasmaphereses [x4], high-dose IVIG [2 g/kg] repeated every 3 weeks for 3 rounds and rituximab [375 mg per square meter of body-surface area]) were prospectively enrolled between April 1, 2013, and July 1, 2014 (N=6). They received C1-INH (20 U/kg twice weekly) and high-dose IVIG (2 g/kg bw every 3 weeks) for 6 months. C1-INH patients were compared with a historical control group treated with high-dose IVIG alone (N=21). The primary endpoint was allograft function (eGFR) changes between the groups at 6 months after inclusion. Secondary end points included allograft histology, donor-specific anti-HLA antibody (DSA) characteristics and adverse events in the C1-INH group, as evaluated at 6 months after inclusion.

The C1-INH group showed a significant improvement in eGFR compared with the control group: +16.6±9.9% vs. -13.0±33.1% (p=0.01). The mean eGFR at the end of the study was of 45.2±21.3 mL/min/1.73 m2 in the C1-INH group vs. 31.7±14.6 in the control group (p=0.08). All patients in the C1-INH group showed an improvement in eGFR between inclusion and study end from 38.7±17.9 mL/min/1.73 m2 to 45.2±21.3 mL/min/1.73 m2 (p=0.03). There was no change in the histological features in patients in the C1-INH group between the biopsies at inclusion and those obtained at the end of the study, except for a significant decrease in the C4d deposition rate (83% vs 17%, respectively, p=0.04). There was a significant change in anti-HLA DSA C1q-binding status from 6/6 (100%) positive at enrolment to 1/6 (17%) positive at the end of the study (p=0.02). One deep venous thrombosis of a lower limb occurred during follow-up.

C1-inhibitor added to high-dose IVIG may improve allograft function in kidney recipients with non-responsive acute AMR.


A propos de Alexandre Loupy


Dr Alexandre Loupy is a 36-year-old Nephrologist at the Department of Nephrology and Kidney Transplantation at Necker Hospital in Paris, France. He started his fellowship in November 2011 and is now part of the department as an associate professor at Necker Hospital.

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