A. R. Shields

Early and Late Acute Antibody-Mediated Rejection Differ Immunologically and in Response to Proteasome Inhibition

Background. The efficacy of plasma cell targeted therapies for antibody-mediated rejection (AMR) has not been defined in detail. The purpose of this study was to compare early and late acute AMR in terms of immunologic characteristics and responses with proteasome inhibitor (PI) therapy. Methods. Renal transplant recipients with acute AMR were treated with PI-based regimens. Early acute AMR was defined as occurring within 6 months posttransplant. Immunodominant donor-specific antibody (iDSA) was defined as the DSA with the highest level. Results. Results are expressed as early or late acute AMR. Thirty AMR episodes (13 early, 17 late) were treated in 12 and 16 patients. Early but not late AMR was associated with presensitization. Late AMR iDSA levels were higher, and specificities were primarily class II (DQ being most frequent). Early AMR patients demonstrated greater reduction in iDSA at 7, 14, and 30 days and at the posttreatment nadir (81.5%+21.2% vs. 51.4%+27.6%; P<0.01). Early AMR patients were more likely to demonstrate histologic resolution/improvement (87.5% vs. 53.8%; P=0.13). Both groups demonstrated significant improvement in renal function. Conclusions. Early and late AMR exhibit distinct immunologic characteristics and respond differently to PI therapy.

Prospective Iterative Trial of Proteasome Inhibitor-Based Desensitization

A prospective iterative trial of proteasome inhibitor (PI)‐based therapy for reducing HLA antibody (Ab) levels was conducted in five phases differing in bortezomib dosing density and plasmapheresis timing. Phases included 1 or 2 bortezomib cycles (1.3 mg/m2 × 6–8 doses), one rituximab dose and plasmapheresis. HLA Abs were measured by solid phase and flow cytometry (FCM) assays. Immunodominant Ab (iAb) was defined as highest HLA Ab level. Forty‐four patients received 52 desensitization courses (7 patients enrolled in multiple phases): Phase 1 (n = 20), Phase 2 (n = 12), Phase 3 (n = 10), Phase 4 (n = 5), Phase 5 (n = 5). iAb reductions were observed in 38 of 44 (86%) patients and persisted up to 10 months. In Phase 1, a 51.5% iAb reduction was observed at 28 days with bortezomib alone. iAb reductions increased with higher bortezomib dosing densities and included class I, II, and public antigens (HLA DRβ3, HLA DRβ4 and HLA DRβ5). FCM median channel shifts decreased in 11/11 (100%) patients by a mean of 103 ± 54 mean channel shifts (log scale). Nineteen out of 44 patients (43.2%) were transplanted with low acute rejection rates (18.8%) and de novo DSA formation (12.5%). In conclusion, PI‐based desensitization consistently and durably reduces HLA Ab levels providing an alternative to intravenous immune globulin‐based desensitization.

Prospective evaluation of the toxicity profile of proteasome inhibitor-based therapy in renal transplant candidates and recipients.

Background A prospective intermediate-term evaluation of toxicities associated with bortezomib therapy for antibody-mediated rejection (AMR) and desensitization was conducted. Methods Patients were graded for bortezomib-related toxicities: hematologic and gastrointestinal toxicities by Common Terminology Criteria for Adverse Events and peripheral neuropathy by modified Functional Assessment of Cancer Therapy questionnaire and Common Terminology Criteria for Adverse Events. Results Fifty-one patients treated for AMR and 19 patients treated for desensitization received 96 bortezomib cycles (1.3 mg/m2 ×4 doses); mean (SD) follow-up was 16.3 (9.0) months. Patients treated for AMR and patients treated for desensitization were similar in age, gender, ethnicity, and baseline peripheral neuropathy. Patients treated for AMR received a mean (SD) of 4.9 (2.0) bortezomib doses in 1.3 (0.5) cycles; and patients treated for desensitization, a mean of 7.3 (1.6) doses in 1.8 (0.4) cycles. Prevalence of diabetes and anemia were higher at baseline in patients treated for AMR. In the AMR cohort, two cases of cytomegalovirus infection, two cases of BK virus infection, and one case of Epstein-Barr virus infection were observed. No cases of viral infection were observed in the desensitization cohort. Malignancies were not observed. Significant bortezomib toxicities included anemia and peripheral neuropathy, which were manageable. Anemia was more common in patients treated for AMR; and peripheral neuropathy, more common in patients treated for desensitization. Conclusions Bortezomib-related toxicities in kidney transplant candidates and recipients are low in incidence and severity and vary based on treatment population.

Desensitization in kidney transplantation: review and future perspectives.

More than half of the kidney transplant candidates awaiting transplantation are sensitized to human leukocyte antigens (HLAs). Desensitization to HLAs involves treatment with immunomodulating therapies designed to reduce levels of anti‐HLA antibodies in order to make kidney transplantation possible. Over the last two decades, desensitization therapies have been limited to plasmapheresis (PP), immunoadsorption (IA), intravenous immunoglobulins (IVIg), and rituximab. Review of reported experiences with desensitization in kidney transplant candidates revealed that PP or IA alone is inadequate to achieve durable reductions in HLA antibodies. Increasing evidence has accumulated indicating that high‐dose IVIg has limited ability to reduce HLA antibodies, but a few centers have reported success with high‐dose IVIg+rituximab in non‐randomized trials. Overall experience in multiple centers, however, has shown high antibody‐mediated rejection (AMR) rates, particularly in patients with the highest degrees of HLA sensitization. Low‐dose IVIg combined with alternate day PP in living donor transplant candidates has been shown to provide enhanced survival over dialysis. However, low‐dose IVIg/PP regimens also continue to be associated with unacceptable AMR rates. Recent experiences with plasma cell‐targeted therapies based on the proteasome inhibitor bortezomib are relatively small but may represent an important alternative to non‐deletional strategies with IVIg.

Randomized controlled pilot study of B cell-targeted induction therapy in HLA sensitized kidney transplant recipients.

Optimal induction regimens for patients at high risk for antibody and/or cell–mediated rejection have not been established. This pilot, prospective, randomized study evaluated addition of B cell/plasma cell–targeting agents to T cell–based induction with rabbit antithymocyte globulin (rATG) in high immunologic risk renal transplant recipients. Patients were randomized to induction with rATG, rATG + rituximab, rATG + bortezomib or rATG + rituximab + bortezomib. Inclusion criteria were: (1) current cytotoxic panel reactive antibody (PRA) ≥20% or peak cytotoxic PRA ≥50% or (2) T or B cell positive flow crossmatch with donor‐specific antibody (DSA) or (3) historical positive serologic or cytotoxic crossmatch or DSA to donor or (4) prior allograft loss with more than one acute rejection. Median overall follow‐up was 496 days: 1‐year and overall acute rejection were 25% and 27.5%, and 25% of patients developed de novo DSA within 1 year. One‐year and overall patient survival were 97.5% and 92.5%, and 1‐year and overall death‐censored allograft survival were 97.5% and 95%. Renal allograft function posttransplant was similar among all arms. Eight of nine cases of peripheral neuropathy were mild, whereas one case was moderate and required a narcotic prescription. In conclusion, addition of rituximab and/or bortezomib to rATG induction has an acceptable safety/toxicity profile in a high immunologic risk renal transplant population.

Proteasome Inhibition for Antibody-Mediated Allograft Rejection

Antibody-mediated rejection (AMR) is a major risk factor for graft loss following kidney transplantation. Traditional anti-humoral therapies provide suboptimal therapy and they do not deplete plasma cells, which are the source of antibody production. Proteasome inhibitors (PI) have been shown to deplete both transformed and nontransformed plasma cells in human transplant recipients and animal models; and therefore, offer a new paradigm for AMR, ie, plasma cell-targeted therapy. Bortezomib, a first in class proteasome inhibitor approved by the US Food and Drug Administration for treatment of multiple myeloma, has been used to treat AMR in several solid organ transplant recipients. The greatest experience with PI therapy for treating AMR is in kidney transplant recipients. Experiences to date with PI therapy have demonstrated that: (1) early AMR (within the first 6 months post-transplant) responds better than late AMR, and (2) the nature of the plasma cell clonal population influences sensitivity to PI therapy with plasma subsets greater than long-lived bone marrow niche-resident plasma cells. In conclusion, plasma cell-targeted therapy with PIs is a method for targeting plasma cells (the source of antibody production) with a well-elucidated mechanism of action and subsequent points of synergy, thereby providing an exciting new potential means for enhancing anti-humoral therapies.

A Banff Component Scoring-based Histologic Assessment of Bortezomib-based Antibody-mediated Rejection Therapy.

Background Histology remains a cornerstone for antibody-mediated rejection (AMR) diagnosis. Little data exist supporting histology for assessing therapeutic responses. This study evaluates histologic components in assessing AMR therapeutic responses. Methods Antibody-mediated rejection was diagnosed using Antibody Working Group criteria and Banff component scoring, and C4d staining data were analyzed. Statistics included independent and paired samples t test, &khgr;2, Fisher exact, or the Wilcoxon-signed rank test. Fifty-five AMR patients were analyzed. Early AMR was defined as occurring within 6 months after transplantation and treated with a single rituximab dose and 4 bortezomib doses preceded by plasmapheresis. Allograft biopsies were performed within 48 hours of treatment; repeat biopsy was performed 14 to 21 days later. Results Early AMR demonstrated histologic improvement in mean scores for acute Banff components glomerulitis (g), C4d, g+ peritubular capillaritis (ptc) and acute composite score, but showed deterioration in chronic Banff components tubular atrophy and interstitial fibrosis. Late AMR showed improved mean scores for acute Banff components tubulitis, interstitial inflammation, g, ptc, g + ptc, C4d, and acute composite score, but chronic scores did not change. Significant changes in distribution of Banff scores after treatment were observed for g, C4d, tubular atrophy, and interstitial fibrosis scores in early AMR patients and tubulitis, interstitial inflammation, g, ptc, and C4d in late AMR. Conclusions These results show that: (1) Banff component scoring provides insights into histologic responses to AMR therapy and may provide a potential endpoint for clinical AMR trials. (2) Early and late AMR demonstrate differences in acute and chronic Banff components at the time of the AMR diagnostic biopsy, as well as differential responses to AMR therapy.

Contrast-Induced Nephropathy in Renal Transplant Recipients: A Single Center Experience

Background Contrast-induced nephropathy (CIN) in native kidneys is associated with a significant increase in mortality and morbidity. Data regarding CIN in renal allografts are limited, however. We retrospectively studied CIN in renal allografts at our institution: its incidence, risk factors, and effect on long-term outcomes including allograft loss and death. Methods One hundred thirty-five renal transplant recipients undergoing 161 contrast-enhanced computed tomography (CT) scans or coronary angiograms (Cath) between years 2000 and 2014 were identified. Contrast agents were iso- or low osmolar. CIN was defined as a rise in serum creatinine (SCr) by >0.3 mg/dl or 25% from baseline within 4 days of contrast exposure. After excluding 85 contrast exposures where patients had no SCr within 4 days of contrast administration, 76 exposures (CT: n = 45; Cath: n = 31) in 50 eligible patients were analyzed. Risk factors assessed included demographics, comorbid conditions, type/volume of contrast agent used, IV fluids, N-acetylcysteine administration, and calcineurin inhibitor use. Bivariate and multivariable analyses were used to assess the risk of CIN. Results Incidence of CIN was 13% following both, CT (6 out of 45) and Cath (4 out of 31). Significant bivariate predictors of CIN were IV fluid administration (p = 0.05), lower hemoglobin (p = 0.03), and lower albumin (p = 0.02). In a multivariable model, CIN was predicted by N-acetylcysteine (p = 0.03) and lower hemoglobin (p = 0.01). Calcineurin inhibitor use was not associated with CIN. At last follow-up, CIN did not affect allograft or patient survival. Conclusion CIN is common in kidney transplant recipients, and there is room for quality improvement with regards to careful renal function monitoring post-contrast exposure. In our study, N-acetylcysteine exposure and lower hemoglobin were associated with CIN. Calcineurin inhibitor use was not associated with CIN. Our sample size is small, however, and larger prospective studies of CIN in renal allografts are needed.

Pharmacokinetic and Pharmacogenetic Analysis of Immunosuppressive Agents after Laparoscopic Sleeve Gastrectomy

Severe obesity has been shown to limit access to renal transplantation in patients with end‐stage renal disease (ESRD). Laparoscopic sleeve gastrectomy (LSG) has been performed in the ESRD population to assist in achieving waitlist and transplant eligibility. Little is known about how LSG impacts the bioequivalence of tacrolimus products and immunosuppression pharmacokinetics.

MULTIVARIATE ANALYSES OF ACUTE REJECTION IN RENAL TRANSPLANT RECIPIENTS RECEIVING EARLY CORTICOSTEROID WITHDRAWAL: 104

A.R. Shields1, R.R. Alloway2, G. Mogilishetty2, M. Cardi3, S. Huang3, L. Arend4, P. Brailey5, R. Munda6, J. Everly7, E.S. Woodle6 1Transplant Surgery, University of Cincinnati, Cincinnati/Ohio/UNITED STATES OF AMERICA, 2Nephrology, University of Cincinnati, cincinnati/UNITED STATES OF AMERICA, 3Nephrology, The Christ Hospital, cincinnati/UNITED STATES OF AMERICA, 4Pathology, University of Cincinnati, cincinnati/UNITED STATES OF AMERICA, 5Hoxworth Immunology, University of Cincinnati, cincinnati/UNITED STATES OF AMERICA, 6Transplant Surgery, University of Cincinnati, cincinnati/UNITED STATES OF AMERICA, 7, Oncology Hematology, Inc, cincinnati/UNITED STATES OF AMERICA