Alemtuzumab as compared to alternative contemporary induction regimens

Outcomes based on induction regimens in pediatric kidney transplantation: a NAPRTCS and PHIS collaborative study

BACKGROUND

Induction agent used at the time of kidney transplant is often based upon center practice and recipient characteristics. We evaluated outcomes across induction therapies among children enrolled in the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) transplant registry with data in the Pediatric Health Information System (PHIS).

METHODS

This is a retrospective study of merged data from NAPRTCS and PHIS. Participants were grouped by induction agent: interleukin-2 receptor blocker (IL-2 RB), anti-thymocyte/anti-lymphocyte globulin (ATG/ALG), and alemtuzumab. Outcomes assessed included 1-, 3-, and 5-year allograft function and survival, rejection, viral infections, malignancy, and death.

RESULTS

A total of 830 children transplanted between 2010 and 2019. At 1 year post-transplant, the alemtuzumab group had higher median eGFR (86 ml/min/1.73 m2) compared to IL-2 RB and ATG/ALG (79 and 75 ml/min/1.73 m2, respectively; P < 0.001); at 3 and 5 years, there was no difference. Adjusted eGFR over time was similar across all induction agents. Rejection rates were lower among the alemtuzumab group vs. IL-2RB and ATG (13.9% vs. 27.3% and 24.6%, respectively; P = 0.006). Adjusted ATG/ALG and alemtuzumab had higher hazard ratio for time to graft failure compared to IL-2 RB (HR 2.48 and HR 2.11, respectively; P < 0.05). Incidence of malignancy, mortality, and time to first viral infection was similar.

CONCLUSION

Although rejection and allograft loss rates were distinct, the incidences of viral infection and malignancy were comparable across induction agents. By 3 years post-transplant, there was no difference in eGFR. A higher resolution version of the Graphical abstract is available as Supplementary information.

Risks and ways of preventing kidney dysfunction in drug-induced immunosuppression in solid organ recipients

Immunosuppressive therapy (IMT) is the cornerstone of treatment after transplantation. The goal of immunosuppression is to prevent acute and chronic rejection while maximizing patient survival and long-term graft function. However, the expected effects of IMT must be balanced against the major adverse effects of these drugs and their toxicity. The purpose of this review is to summarize world experience on current immunosuppressive strategies and to assess their effects on renal function.

Incidence, risk factors, treatment, and consequences of antibody-mediated kidney transplant rejection: A systematic review

BACKGROUND

Antibody-mediated rejection (AMR) is a leading cause of kidney allograft failure, but its incidence, risk factors, and outcomes are not well understood.

METHODS

We searched Ovid MEDLINE, Cochrane, EMBASE, and Scopus from January 2000 to January 2020 to identify published cohorts of ≥500 incident adult or 75 pediatric kidney transplant recipients followed for ≥1 year post-transplant.

RESULTS

At least two reviewers screened 5061 articles and abstracts; 28 met inclusion criteria. Incidence of acute AMR was 1.1%-21.5%; most studies reported 3%-12% incidence, usually within the first year post-transplant. Few studies reported chronic AMR incidence, from 7.5%-20.1% up to 10 years. Almost all patients with acute or chronic AMR received corticosteroids and intravenous immunoglobulin; most received plasmapheresis, and approximately half with rituximab. Most studies examining death-censored graft failure identified AMR as an independent risk factor. Few reported refractory AMR rates or outcomes, and none examined costs. Most studies were single-center and varied greatly in design.

CONCLUSIONS

Cohort studies of kidney transplant recipients demonstrate that AMR is common and associated with increased risk of death-censored graft failure, but studies vary widely regarding populations, definitions, and reported incidence. Gaps remain in our understanding of refractory AMR, its costs, and resulting quality of life.

Human cytomegalovirus infection: A considerable issue following allogeneic hematopoietic stem cell transplantation

Cytomegalovirus (CMV) is an opportunistic virus, whereby recipients are most susceptible following allogeneic hematopoietic stem cell transplantation (allo-HSCT). With the development of novel immunosuppressive agents and antiviral drugs, accompanied with the widespread application of prophylaxis and preemptive treatment, significant developments have been made in transplant recipients with human (H)CMV infection. However, HCMV remains an important cause of short- and long-term morbidity and mortality in transplant recipients. The present review summarizes the molecular mechanism and risk factors of HCMV reactivation following allo-HSCT, the diagnosis of CMV infection following allo-HSCT, prophylaxis and treatment of HCMV infection, and future perspectives. All relevant literature were retrieved from PubMed and have been reviewed.

Opportunistic Infections After Induction With Alemtuzumab or Basiliximab: A 3-Year Kidney Transplantation Experience

BACKGROUND

Antibody induction immunosuppression is commonly used in kidney transplantation to decrease the risk of early acute rejection. However, infectious complications may arise in patients treated with higher intensity induction immunosuppression. In this study, we compared the rate of opportunistic infections during the 3 years after kidney transplantation in recipients who received either alemtuzumab or basiliximab for induction therapy.

METHODS

All renal transplant recipients from our center who received induction with alemtuzumab between 2011 and 2016 were included and matched 1:2 (by age and date of transplant) to renal transplant recipients who received basiliximab. The primary outcome was the rate of opportunistic infections.

RESULTS

Twenty-seven patients received alemtuzumab (mean age = 50.8 years; SD ±12), and 54 received basiliximab (mean age = 50.8 years; SD ±11.8). Infections within 3 years posttransplant were not different between groups: BK viremia (P = .99), BK nephritis (P = .48), cytomegalovirus infection (P = .13), varicella zoster virus (P = .22), and all infections (P = .87). Time to infection (P = .67), patient survival (P = .21), and time to rejection (P = .098) were similar in both groups. There were also no group differences in delayed graft function (P = .76), graft loss (P = .97), or rejection (P = .2).

CONCLUSION

The rate of infection was not significantly increased in recipients receiving lymphocyte-depleting alemtuzumab compared to recipients receiving basiliximab induction therapy, despite receiving similar maintenance immunosuppression. Although the immunologic risks differed between the 2 groups, there was no observable difference in clinical outcomes.

Immunosuppression Has Long-Lasting Effects on Circulating Follicular Regulatory T Cells in Kidney Transplant Recipients

Background: FoxP3⁺ follicular regulatory T cells (Tfr) have been identified as the cell population controlling T follicular helper (Tfh) cells and B cells which, are both involved in effector immune responses against transplanted tissue.

Methods: To understand the biology of Tfr cells in kidney transplant patients treated with tacrolimus and mycophenolate mofetil (MMF) combination immunosuppression, we measured circulating (c)Tfh and cTfr cells in peripheral blood by flow cytometry in n = 211 kidney transplant recipients. At the time of measurement patients were 5–7 years after transplantation. Of this cohort of patients, 23.2% (49/211) had been previously treated for rejection. Median time after anti-rejection therapy was 4.9 years (range 0.4–7 years). Age and gender matched healthy individuals served as controls.

Results: While the absolute numbers of cTfh cells were comparable between kidney transplant recipients and healthy controls, the numbers of cTfr cells were 46% lower in immunosuppressed recipients (p < 0.001). More importantly, in transplanted patients, the ratio of cTfr to cTfh was decreased (median; 0.10 vs. 0.06), indicating a disruption of the balance between cTfr and cTfh cells. This shifted balance was observed for both non-rejectors and rejectors. Previous pulse methylprednisolone or combined pulse methylprednisolone + intravenous immunoglobulin anti-rejection therapy led to a non-significant 30.6% (median) and 51.2% (median) drop in cTfr cells, respectively when compared to cTfr cell numbers in transplant patients who did not receive anti-rejection therapy. A history of alemtuzumab therapy did lead to a significant decrease in cTfr cells of 85.8% (median) compared with patients not treated with anti-rejection therapy (p < 0.0001). No association with tacrolimus or MMF pre-dose concentrations was found.

Conclusion: This cross-sectional study reveals that anti-rejection therapy with alemtuzumab significantly lowers the number of cTfr cells in kidney transplant recipients. The observed profound effects by these agents might dysregulate cTfr functions.

Early outcomes comparing induction with antithymocyte globulin vs alemtuzumab in two steroid-avoidance protocols in pediatric renal transplantation

Steroid avoidance in pediatric kidney transplants was found effective with extended daclizumab induction. Upon discontinuation of daclizumab, lymphocyte-depleting agents became used, with little comparative data. We assessed outcomes in children undergoing low immunologic-risk deceased donor (DD) kidney transplants using induction with antithymocyte globulin (ATG) compared to alemtuzumab. We reviewed consecutive DD kidney transplants from January 2015 to September 2017 at two pediatric centers that used different lymphocyte-depleting agents in steroid-avoidance protocols: ATG (Center A) and alemtuzumab (Center B), with tacrolimus and MMF as maintenance immunosuppression. Anti-infective prophylaxis was based on center protocol. Over the first year post-tx, there were similar rates of infections. EBV and BK viremia were comparable though Center A manifested more low-grade CMV viremia (A 46% vs B 0%; P = .0009) at median onset 1.8 months, followed by early seroconversion. Reduction of immunosuppression did not differ between groups. DSA at 1 year was similar (A 8% vs 13%) with low rates of BPAR. Need for steroid-based conversion was low. There were no graft losses and no differences in median eGFR at 30, 90, 180, and 365 days. (a) 1-year graft outcomes are excellent in steroid-avoidance regimens using ATG or alemtuzumab induction; (b) conversion to steroid-based therapy is low; (c) alemtuzumab/high-dose MMF is associated with lower WBC and more GCSF use; (d) alemtuzumab/higher dose MMF results in more diarrhea and azathioprine conversion than ATG/lower dose MMF; (e) CMV viremia is seen more often with ATG use with infection prophylaxis reduction; however, seroconversion occurs promptly.

Outcomes of induction antibody therapies in the nonbroadly sensitized adult deceased donor kidney transplant recipients: a retrospective cohort registry analysis

The outcomes of lymphocyte-depleting antibody induction therapy (LDAIT), [thymoglobulin (ATG) or alemtuzumab (ALM)] versus interleukin-2 receptor antagonist (IL-2RA) in the nonbroadly-sensitized [pretransplant calculated panel reactive antibody (cPRA), <80%] adult deceased donor kidney transplant recipients (adult-DDKTRs) are understudied. In this registry, study of 55 593 adult-DD-KTRs, outcomes of LDAIT [(ATG, N = 32 985) and (ALM, N = 9429)], and IL-2RA (N = 13 179) in <10% and 10-79% cPRA groups was analyzed. Adjusted odds ratio (aOR) of one-year biopsy-proven acute rejection (BPAR) was lower; while, aOR of 1-year composite of re-hospitalization, graft loss, or death was higher with LDAIT than IL2-RA in both cPRA groups. Adjusted odds ratio (aOR) of delayed graft function was higher with LDAIT than IL-2RA in the <10% cPRA group. Adjusted hazard ratio (aHR) of 5-year death-censored graft loss (DCGL) in both <80% cPRA groups seemed higher with ALM than other inductions [(<10% cPRA: ALM versus IL2RA, aHR = 1.11, 95% CI = 1.00-1.23 and ATG versus ALM: aHR = 0.84, 95% CI = 0.77-0.91; 10-79% cPRA: ALM versus IL2RA, aHR = 1.29, 95% CI = 1.02-1.64; and ATG versus ALM, aHR = 0.83, 95% CI = 0.70-0.98)]. Five-year aHR of death did not differ among induction therapies in both cPRA groups. In nonbroadly sensitized adult-DDKTRs, LDAIT is more protective against 1-year BPAR (not 5-year mortality) than IL-2RA; the trend of a higher 5-year DCGL risk with ALM than ATG or IL-2RA needs further investigation.

Low dose valganciclovir as cytomegalovirus prophylaxis in post-renal transplant recipients induced with alemtuzumab: A single-center study

OBJECTIVES

Alemtuzumab (Ale) is a recombinant monoclonal antibody which binds to CD52 causing profound lymphodepletion, thus allowing its use in renal transplantation induction therapy. However, patients may be at increased risk for opportunistic infections, such as Cytomegalovirus (CMV). We analyzed CMV infection in renal allograft recipients administered low-dose valganciclovir (VGCV) prophylaxis with alemtuzumab induction and steroid minimization.

MATERIALS AND METHODS

In this retrospective analysis, 678 kidney transplant recipients were evaluated, with 606 included for analysis. Patients were excluded for receiving induction therapy other than Ale, or for lack of follow-up within 1 year. VGCV prophylaxis was stratified by recipient CMV risk status and low-dose (450 mg) VGCV was given 3 times a week to low and moderate risk patients and daily to high risk individuals. Subject records were examined for recipient demographics, donor and recipient CMV serostatus, CMV viremia, and invasive infection.

RESULTS

Of the 606 recipients, 154 were defined as low risk for CMV infection (donor and recipient both negative, or D-/R-), 236 as moderate risk without mismatch (D+/R+), 122 as moderate risk with mismatch (D-/R+), and 94 as high risk (D+/R-). Twenty-nine (29) individuals (4.8%) tested positive by PCR for CMV viremia and 10 (1.7%) patients developed invasive CMV disease, including colitis (n = 4), esophagitis (n = 1), enteritis (n = 1), nephritis (n = 1), and pneumonia (n = 3). High risk recipients (D+/R-) accounted for the majority of invasive CMV disease (n = 5), followed by moderate risk (n = 4). CMV viremia was also more common in high risk and moderate risk (D+/R+) individuals. Overall rejection rate for our study population was 27%.

CONCLUSION

In this institution's experience, CMV incidence was reduced compared to historically reported data by using low-dose (450 mg) VGCV prophylaxis in combination with Ale induction and steroid minimization. However, overall rejection rate was significantly higher in our population, possibly influenced by the degree of steroid minimization.

Review of the Clinical Pharmacokinetics and Pharmacodynamics of Alemtuzumab and Its Use in Kidney Transplantation

Alemtuzumab is a humanized monoclonal antibody against CD52 and causes depletion of T and B lymphocytes, monocytes, and NK cells. Alemtuzumab is registered for the treatment of multiple sclerosis (MS) and is also used in chronic lymphocytic leukemia (CLL). Alemtuzumab is used off-label in kidney transplantation as induction and anti-rejection therapy. The objective of this review is to present a review of the pharmacokinetics, pharmacodynamics, and use of alemtuzumab in kidney transplantation. A systematic literature search was conducted using Ovid Medline, Embase, and Cochrane Central Register of controlled trials. No pharmacokinetic or dose-finding studies of alemtuzumab have been performed in kidney transplantation. Although such studies were conducted in patients with CLL and MS, these findings cannot be directly extrapolated to transplant recipients, because CLL patients have a much higher load of CD52-positive cells and, therefore, target-mediated clearance will differ between these two indications. Alemtuzumab used as induction therapy in kidney transplantation results in a lower incidence of acute rejection compared to basiliximab therapy and comparable results as compared with rabbit anti-thymocyte globulin (rATG). Alemtuzumab used as anti-rejection therapy results in a comparable graft survival rate compared with rATG, although infusion-related side effects appear to be less. There is a need for pharmacokinetic and dose-finding studies of alemtuzumab in kidney transplant recipients to establish the optimal balance between efficacy and toxicity. Furthermore, randomized controlled trials with sufficient follow-up are necessary to provide further evidence for the treatment of severe kidney transplant rejection.

Very Early Cytomegalovirus Infection After Renal Transplantation: A Single-Center 20-Year Perspective

Background:

Cytomegalovirus (CMV) infection risk in the first month after transplantation is felt to be minimal; however, the epidemiology has not been specifically investigated, particularly in the modern era of potent immunosuppressive regimens and universal CMV prophylaxis.

Objective:

The aim of this study was to describe the incidence of and risk factors associated with CMV occurring less than 30 days after transplant and evaluate the effect of very early CMV on outcomes.

Methods:

Retrospective, single-center study of adult renal transplant (RTX) recipients between January 1, 1994 and December 31, 2014.

Results:

A total of 5225 patients who received a renal transplant in the study time period were reviewed for the presence of CMV infection occurring less than 30 days after transplant. Of these, only 14 patients demonstrated this finding for an overall incidence of 0.27%. Half of these patients were considered to be at heightened risk due to being a recipient of a non-primary transplant or on chronic immunosuppression. This left seven patients without known risk factors for very early CMV to evaluate. In this group, time from transplant to CMV infection was 13.5 ± 7 days. The majority (57.1%, n = 4) were high-risk serostatus (CMV D+/R−) and occurred in the valganciclovir era (71.4%, n = 5). Lymphocyte-depleting induction predominated (57.1%, n = 4). Average cold ischemic time (CIT) was 19.7 ± 7.7 hours. Three patients had post-operative complications, two required exploratory-laparotomy for hemorrhage. When evaluating outcomes, 43% (n = 3) had subsequent episodes of CMV infection, 28.6% (n = 2) developed rejection, and 28.6% (n = 2) died. Outcomes between patients with CMV infection less than 30 days and those with CMV infection more than 30 days after transplant were not significantly different.

Conclusions:

In our review of over 5000 kidney transplants, the incidence of CMV infection in the first 30 days after renal transplant is 0.2%. Notable common patient characteristics include hemorrhage requiring re-operation and prolonged CIT. Outcomes were similar to CMV occurring more than 30 days after transplant. This study should provide the clinician with some reassurance; despite potent immunosuppressive therapy, CMV infection in the first 30 days is unlikely.

Graft-implanted, enzyme responsive, tacrolimus-eluting hydrogel enables long-term survival of orthotopic porcine limb vascularized composite allografts: A proof of concept study

Background

Currently, patients receiving vascularized composite allotransplantation (VCA) grafts must take long-term systemic immunosuppressive therapy to prevent immunologic rejection. The morbidity and mortality associated with these medications is the single greatest barrier to more patients being able to receive these life-enhancing transplants. In contrast to solid organs, VCA, exemplified by hand or face transplants, allow visual diagnosis of clinical acute rejection (AR), directed biopsy and targeted graft therapies. Local immunosuppression in VCA could reduce systemic drug exposure and limit adverse effects. This proof of concept study evaluated, in a large animal forelimb VCA model, the efficacy and tolerability of a novel graft-implanted enzyme-responsive, tacrolimus (TAC)—eluting hydrogel platform, in achieving long-term graft survival.

Methods

Orthotopic forelimb VCA were performed in single haplotype mismatched mini-swine. Controls (n = 2) received no treatment. Two groups received TAC hydrogel: high dose (n = 4, 91 mg TAC) and low dose (n = 4, 49 mg TAC). The goal was to find a dose that was tolerable and resulted in long-term graft survival. Limbs were evaluated for clinical and histopathological signs of AR. TAC levels were measured in serial blood and skin tissue samples. Tolerability of the dose was evaluated by monitoring animal feeding behavior and weight.

Results

Control limbs underwent Banff Grade IV AR by post-operative day six. Low dose TAC hydrogel treatment resulted in long-term graft survival time to onset of Grade IV AR ranging from 56 days to 93 days. High dose TAC hydrogel also resulted in long-term graft survival (24 to 42 days), but was not well tolerated.

Conclusion

Graft-implanted TAC-loaded hydrogel delays the onset of Grade IV AR of mismatched porcine forelimb VCA grafts, resulting in long term graft survival and demonstrates dose-dependent tolerability.

Postrenal transplant infection: What is the effect of specific immunosuppressant agents?

BACKGROUND

Immunosuppression is a known risk for post-transplant infections. Little data exist on the risk contributions of specific agents for various infections.

METHODS

A triply robust propensity score-adjusted analysis was performed in a renal transplant cohort between February 2006 and January 2014. The study was performed to identify the incidence and the risk factors for developing a post-transplant infection. After initial bivariate analysis, a triply robust propensity score-adjusted multivariate logistic regression was performed.

RESULTS

The mean age of the 717 renal transplant recipients was 50.0 ± 13.3 years, with the majority being male (61.6%) and 349 (48.7%) experiencing at least 1 post-transplant infection. Neither race, graft type, nor insurance status was associated with an increased incidence or risk of infection. In a fully adjusted regression model, the immunosuppressants mycophenolic acid mofetil (OR 0.38, 95% CI 0.21-0.71; P < .001) and alemtuzumab (OR 0.40, 95% CI 0.19-0.85; P = .020) were protective.

CONCLUSION

Alemtuzumab and mycophenolic acid mofetil as immunosuppressant agents in a multiagent protocol appear to decrease the incidence of infection. Cytomegalovirus antigenemia was the greatest risk for infection and mycophenolic acid mofetil possessed the greatest protective effect on viral infections.

Overview of Immunosuppressive Therapy in Solid Organ Transplantation

Mechanisms of rejection, new pharmacologic approaches, and genomic medicine are major foci for current research in transplantation. It is hoped that these new agents and personalized immunosuppression will provide for less toxic regimens that are effective in preventing both acute and chronic allograft rejection. Until new agents are available, practitioners must use various combinations of currently approved agents to find the best regimens for improved long-term outcomes.

Anesthesia and Perioperative Care in Reconstructive Transplantation

Reconstructive transplantation of vascularized composite allografts (VCAs), such as upper extremity, craniofacial, abdominal, lower extremity, or genitourinary transplants, has emerged as a cutting-edge specialty, with more than 50 programs in the United States and 30 programs across the world performing these procedures. Most VCAs involve complicated technical planning and preparation, protracted surgery, and complex immunosuppressive or immunomodulatory protocols, each associated with unique anesthesiology challenges. This article outlines key procedural, patient, and protocol-related aspects of VCA relevant to anesthesiology management with the goal of ensuring patient safety and optimizing surgical, immunologic, and functional outcomes.

Crosstalk Between T and B Cells in the Germinal Center After Transplantation

Crosstalk between B and T cells in transplantation is increasingly recognized as being important in the alloimmune response. T cell activation of B cells occurs by a 3-stage pathway, culminating with costimulation signals. We review the distinct T cell subtypes required for B-cell activation and discuss the formation of the germinal center (GC) after transplantation, with particular reference to the repopulation of the GC after depletional induction, and the subsequent effect of immunosuppressive manipulation of T cell-B cell interactions. In addition, ectopic GCs are seen in transplantation, but their role is not fully understood. Therapeutic options to target T cell-B cell interactions are of considerable interest, both as immunosuppressive tools, and to aid in the further understanding of these important alloimmune mechanisms.

Renal Transplantation With Final Allocation Based on the Virtual Crossmatch

Solid phase immunoassays (SPI) are now routinely used to detect HLA antibodies. However, the flow cytometric crossmatch (FCXM) remains the established method for assessing final donor-recipient compatibility. Since 2005 we have followed a protocol whereby the final allocation decision for renal transplantation is based on SPI (not the FCXM). Here we report long-term graft outcomes for 508 consecutive kidney transplants using this protocol. All recipients were negative for donor-specific antibody by SPI. Primary outcomes are graft survival and incidence of acute rejection within 1 year (AR <1 year) for FCXM+ (n = 54) and FCXM- (n = 454) recipients. Median follow-up is 7.1 years. FCXM+ recipients were significantly different from FCXM- recipients for the following risk factors: living donor (24% vs. 39%, p = 0.03), duration of dialysis (31.0 months vs. 13.5 months, p = 0.008), retransplants (17% vs. 7.3%, p = 0.04), % sensitized (63% vs. 19%, p = 0.001), and PRA >80% (20% vs. 4.8%, p = 0.001). Despite these differences, 5-year actual graft survival rates are 87% and 84%, respectively. AR <1 year occurred in 13% FCXM+ and 12% FCXM- recipients. Crossmatch status was not associated with graft outcomes in any univariate or multivariate model. Renal transplantation can be performed successfully, using SPI as the definitive test for donor-recipient compatibility.

Advances in pharmacotherapy to treat kidney transplant rejection

INTRODUCTION

Current immunosuppressive combination therapy provides excellent prevention of T-cell-mediated rejection following renal transplantation; however, antibody-mediated rejection remains of high concern and accounts for a large number of long-term allograft losses. The recent development of protocol biopsies resulted in the definition of subclinical rejection (SCR), showing histologic evidence for rejection but unremarkable clinical course.

AREAS COVERED

This review describes the current knowledge and evidence of pharmacotherapy to treat kidney allograft rejections and covers SCR treatment options. Each substance is analyzed with regard to its classical indication and further discussed for the treatment of other forms of rejection.

EXPERT OPINION

Despite a lack of randomized trials, early acute T-cell-mediated rejection can be treated effectively in most cases without graft loss. The necessity to treat SCR is currently unclear. Due to a lack of effective therapies, new treatment approaches for antibody-mediated rejection are an urgent medical need to improve long-term outcomes. Future research should aim to better define pathophysiology and histology, stratify risk, and develop rational treatment strategies from randomized controlled trials, in order to establish the value of novel therapies in the arsenal of rejection pharmacotherapy. However, the effective prevention of rejection with minimal side effects still remains the goal in immunosuppression.

Alemtuzumab induction and antibody-mediated rejection in kidney transplantation

BACKGROUND

Induction therapy improves graft outcomes in kidney transplant recipients (KTRs). We aimed to compare the incidences of antibody-mediated rejection (AMR) and acute cellular rejection (ACR) as well as graft and patient outcomes in KTRs who underwent induction with alemtuzumab versus rabbit-antithymocyte globulin (r-ATG).

METHODS

This was a single-center retrospective study involving patients who underwent kidney transplantation between January 2009 and December 2011 after receiving induction therapy with either alemtuzumab or r-ATG. Maintenance immunosuppression included tacrolimus and mycophenolate mofetil with early steroid withdrawal. Acute rejection was diagnosed using allograft biopsy.

RESULTS

Among the 108 study patients, 68 received alemtuzumab and 40 got r-ATG. There was a significantly higher incidence of AMR (15% vs 2.5%; P = .008) and similar incidence of ACR (4.4% vs 10%; P = .69) for alemtuzumab versus r-ATG groups. One-year serum creatinine levels (l.68 ± 0.8 mg/dL vs 1.79 ± 1.8 mg/dL; P = .66) as well as graft (91.1 ± 3.5% vs 94.5 ± 3.8%; P = .48) and patient (93.8 ± 3.0% vs 96.4 ± 3.5%; P = .92) survivals were similar for the alemtuzumab versus the r-ATG groups.

CONCLUSION

Our study showed a higher incidence of AMR and similar incidence of ACR in KTRs who underwent induction with alemtuzumab compared with those who received r-ATG and were maintained on tacrolimus and MMF. This was despite a lower HLA mismatch in the alemtuzumab group. One-year graft survival, patient survival, and allograft function were similar. Inadequate B-cell suppression by alemtuzumab as well as altered phenotypic and functional properties of repopulating B cells could be contributing to heightened risk of AMR in these patients.

Incidence and management of leukopenia/neutropenia in 233 kidney transplant patients following single dose alemtuzumab induction

BACKGROUND

The purpose of this study was to determine the incidence and management strategies for post-transplant leukopenia/neutropenia in kidney recipients receiving alemtuzumab induction during the first year following transplantation.

METHODS

We prospectively identified 233 adult patients who underwent kidney transplantation with alemtuzumab induction at a single institution. The incidence and severity of leukopenia (white blood cell count [WBC] ≤2500/mm(3)) and neutropenia (absolute neutrophil count [ANC] ≤500/mm(3)) were evaluated at 1, 3, 6, and 12 months post-transplantation. We determined any association with cytomegalovirus (CMV) infection, graft rejection, and infections requiring hospitalization. We also reviewed interventions performed, including medication adjustments, treatment with granulocyte stimulating factor, and hospitalization.

RESULTS

The combined incidence of either leukopenia or neutropenia was 47.5% (n = 114/233) with an average WBC nadir of 1700 ± 50/mm(3) at 131.0 ± 8.5 days and an average ANC nadir of 1500 ± 100/mm(3) at 130.4 ± 9.6 days. No significant difference in graft rejection, CMV infection, or infections requiring hospitalization was found in the leukopenia/neutropenia group vs the normal WBC group (P = .3). The most common intervention performed for leukopenia/neutropenia group was prophylactic medication adjustment. Six patients (5.2%) required a change in >1 medication. The majority of these patients also required granulocyte stimulating factor (61.5%; 32/52), with an average of 2.5 doses given. A total of 25 patients (21.9%) required hospitalization due to leukopenia/neutropenia with an average length of stay of 6 days.

CONCLUSIONS

Kidney transplant patients receiving alemtuzumab induction required significant interventions due to leukopenia/neutropenia in the first year post-transplantation. These results suggest the need for additional studies aimed at defining the optimum management strategies of leukopenia/neutropenia in this population.

New directions for rabbit antithymocyte globulin (Thymoglobulin(®)) in solid organ transplants, stem cell transplants and autoimmunity

In the 30 years since the rabbit antithymocyte globulin (rATG) Thymoglobulin^® was first licensed, its use in solid organ transplantation and hematology has expanded progressively. Although the evidence base is incomplete, specific roles for rATG in organ transplant recipients using contemporary dosing strategies are now relatively well-identified. The addition of rATG induction to a standard triple or dual regimen reduces acute cellular rejection, and possibly humoral rejection. It is an appropriate first choice in patients with moderate or high immunological risk, and may be used in low-risk patients receiving a calcineurin inhibitor (CNI)-sparing regimen from time of transplant, or if early steroid withdrawal is planned. Kidney transplant patients at risk of delayed graft function may also benefit from the use of rATG to facilitate delayed CNI introduction. In hematopoietic stem cell transplantation, rATG has become an important component of conventional myeloablative conditioning regimens, following demonstration of reduced acute and chronic graft-versus-host disease. More recently, a role for rATG has also been established in reduced-intensity conditioning regimens. In autoimmunity, rATG contributes to the treatment of severe aplastic anemia, and has been incorporated in autograft projects for the management of conditions such as multiple sclerosis, Crohn’s disease, and systemic sclerosis. Finally, research is underway for the induction of tolerance exploiting the ability of rATG to induce immunosuppresive cells such as regulatory T-cells. Despite its long history, rATG remains a key component of the immunosuppressive armamentarium, and its complex immunological properties indicate that its use will expand to a wider range of disease conditions in the future.

Comparison of alemtuzumab vs. antithymocyte globulin induction therapy in primary non-sensitized renal transplant patients treated with rapid steroid withdrawal

Alemtuzumab and rabbit antithymocyte globulin (rATG) are commonly used for induction therapy in renal transplantation. This retrospective, single-center, cohort study evaluated cumulative incidence of one-yr biopsy-proven acute rejection (BPAR) among 200 consecutive primary non-sensitized kidney transplant recipients who received either alemtuzumab (n = 100) or rATG (n = 100) induction followed by rapid steroid taper, tacrolimus, and mycophenolate mofetil. Protocol biopsies, plasma and urine BK virus PCR, serum creatinine and iothalamate glomerular filtration rate (iGFR), were obtained at 1, 4, and 12 months from transplantation. The one-yr BPAR rates were similar between the alemtuzumab and rATG groups; however, rejection Banff IA and higher was more common in the alemtuzumab arm (18% vs. 5%, p = 0.047). After adjusting for confounding variables, alemtuzumab was still associated with Banff IA and higher rejection (adjusted OR: 3.7, CI: 1.2-10.5, p = 0.02). Despite similar rates of BK viremia, more patients in the alemtuzumab arm developed BK nephropathy (16% vs. 3%, p = 0.046). One-year iGFR (53.4 ± 20.2 vs. 71.9 ± 27.2 mL/min/1.73 m(2), p = 0.002) and three-yr graft survival (89.5% vs. 95%, p = 0.05) were lower in the alemtuzumab group. In low immunological risk kidney transplant recipients on steroid-free immunosuppression, alemtuzumab was associated with more severe rejection and BK nephropathy compared to rATG.

Anti-HLA sensitization in extensively burned patients: extent, associated factors, and reduction in potential access to vascularized composite allotransplantation

Extensively burned patients receive iterative blood transfusions and skin allografts that often lead to HLA sensitization, and potentially impede access to vascularized composite allotransplantation (VCA). In this retrospective, single-center study, anti-HLA sensitization was measured by single-antigen-flow bead analysis in patients with deep, second- and third-degree burns over ≥40% total body surface area (TBSA). Association of HLA sensitization with blood transfusions, skin allografts, and pregnancies was analyzed by bivariate analysis. The eligibility for transplantation was assessed using calculated panel reactive antibodies (cPRA). Twenty-nine patients aged 32 ± 14 years, including 11 women, presented with a mean burned TBSA of 54 ± 11%. Fifteen patients received skin allografts, comprising those who received cryopreserved (n = 3) or glycerol-preserved (n = 7) allografts, or both (n = 5). An average 36 ± 13 packed red blood cell (PRBC) units were transfused per patient. In sera samples collected 38 ± 13 months after the burns, all patients except one presented with anti-HLA antibodies, of which 13 patients (45%) had complement-fixing antibodies. Eighteen patients (62%) were considered highly sensitized (cPRA≥85%). Cryopreserved, but not glycerol-preserved skin allografts, history of pregnancy, and number of PRBC units were associated with HLA sensitization. Extensively burned patients may become highly HLA sensitized during acute care and hence not qualify for VCA. Alternatives to skin allografts might help preserve their later access to VCA.

Alemtuzumab for cytolytic induction of immunosuppression in heart transplant recipients

OBJECTIVE

To review available evidence about the safety and efficacy of alemtuzumab for induction of immunosuppression in heart transplant recipients.

DATA SOURCES

Searches of MEDLINE, EMBASE, and Cochrane databases were conducted. Key search terms included alemtuzumab, Campath-1H, CD52, lymphocyte, cytolytic, induction, immunosuppression, rejection, and cardiac transplantation. Additional pertinent data were identified through a search of abstracts from major transplant meetings.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles and abstracts identified from the data sources were evaluated. All primary data were eligible for inclusion if they evaluated the safety or efficacy of alemtuzumab for induction of immunosuppression in heart transplant patients. One retrospective cohort, 1 case series, 1 case-control series, and 1 open-label trial were identified and included for review.

DATA SYNTHESIS

Acute cellular rejection occurs in 40% to 70% of heart transplant recipients within the first 6 months after transplant and is associated with significant morbidity and mortality. Depleting and nondepleting antibodies have displayed positive outcomes in inducing immunosuppression; however, the ideal induction strategy that balances efficacy and toxicity remains elusive. Alemtuzumab, a cytolytic anti-CD52 antibody, has been used to induce immunosuppression in kidney, pancreas, liver, intestine, and lung transplant recipients, and its use in heart transplant has been investigated. Studies of use of alemtuzumab to induce immunosuppression in heart transplant patients have shown low rates of rejection; however, it has not been directly compared with other immunosuppression-inducing agents and safety data are limited.

CONCLUSIONS

Although alemtuzumab may be a practical option for inducing immunosuppression, data are insufficient to recommend its routine use in deference to more established agents. Large, randomized clinical trials with extended durations of follow-up must be conducted to characterize its efficacy and safety further.

B cells and antibodies in multiple sclerosis pathogenesis and therapy

B cells and antibodies account for the most prominent immunodiagnostic feature in patients with multiple sclerosis (MS), namely oligoclonal bands. Furthermore, evidence is accumulating that B cells and antibodies contribute to MS pathogenesis in at least a subset of patients. The CNS provides a B-cell-fostering environment that includes B-cell trophic factors such as BAFF (B-cell-activating factor of the TNF family), APRIL (a proliferation-inducing ligand), and the plasma-cell survival factor CXCL12. Owing to this environment, the CNS of patients with MS is not only the target of the immunopathological process, but also becomes the site of local antibody production. B cells can increase or dampen CNS inflammation, but their proinflammatory effects seem to be more prominent in most patients, as B-cell depletion is a promising therapeutic strategy. Other therapies not primarily designed to target B cells have numerous effects on the B-cell compartment. This Review summarizes key features of B-cell biology, the role of B cells and antibodies in CNS inflammation, and current attempts to identify the targets of pathogenic antibodies in MS. We also review the effects of approved and investigational interventions-including CD20-depleting antibodies, BAFF/APRIL-depleting agents, alemtuzumab, natalizumab, FTY720, IFN-β, glatiramer acetate, steroids and plasma exchange-on B-cell immunology.