Pharmacodynamics of Rituximab in Kidney Transplantation

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Rituximab abrogates aquaporin-4-specific germinal center activity in patients with neuromyelitis optica spectrum disorders

By studying paired blood and deep cervical lymph node samples from patients with neuromyelitis optica spectrum disorders, our data provide evidence for a germinal center–based generation of aquaporin-4 antibodies. Frequent serum aquaporin-4 immunoglobulin Ms (IgMs) and shifts in IgG subclasses were observed alongside preferential synthesis of aquaporin-4 IgGs and aquaporin-4–reactive B cells within lymph nodes. Both intranodal synthesis of aquaporin-4 antibodies and intranodal aquaporin-4–reactive B cells were robustly eliminated with rituximab administration. This study systematically explores lymph nodes that drain the central nervous system (CNS) in patients with CNS autoimmunity and offers a potential explanation as to why rituximab is clinically highly efficacious in autoantibody-mediated diseases despite no accompanying reduction in serum autoantibody levels.

Neuromyelitis optica spectrum disorders (NMOSDs) are caused by immunoglobulin G (IgG) autoantibodies directed against the water channel aquaporin-4 (AQP4). In NMOSDs, discrete clinical relapses lead to disability and are robustly prevented by the anti-CD20 therapeutic rituximab; however, its mechanism of action in autoantibody-mediated disorders remains poorly understood. We hypothesized that AQP4-IgG production in germinal centers (GCs) was a core feature of NMOSDs and could be terminated by rituximab. To investigate this directly, deep cervical lymph node (dCLN) aspirates (n = 36) and blood (n = 406) were studied in a total of 63 NMOSD patients. Clinical relapses were associated with AQP4-IgM generation or shifts in AQP4-IgG subclasses (odds ratio = 6.0; range of 3.3 to 10.8; P < 0.0001), features consistent with GC activity. From seven dCLN aspirates of patients not administered rituximab, AQP4-IgGs were detected alongside specific intranodal synthesis of AQP4-IgG. AQP4-reactive B cells were isolated from unmutated naive and mutated memory populations in both blood and dCLNs. After rituximab administration, fewer clinical relapses (annual relapse rate of 0.79 to 0; P < 0.001) were accompanied by marked reductions in both AQP4-IgG (fourfold; P = 0.004) and intranodal B cells (430-fold; P < 0.0001) from 11 dCLNs. Our findings implicate ongoing GC activity as a rituximab-sensitive driver of AQP4 antibody production. They may explain rituximab’s clinical efficacy in several autoantibody-mediated diseases and highlight the potential value of direct GC measurements across autoimmune conditions.

Hepatocellular carcinoma and cancer-related mortality after kidney transplantation with rituximab treatment

Purpose

There are increased therapeutic usages of rituximab in kidney transplantation (KT). However, few studies have evaluated the effect of rituximab on cancer development following KT. This study aimed to evaluate the effect of rituximab on the cancer occurrence and mortality rate according to each type of cancer.

Methods

Five thousand consecutive recipients who underwent KT at our center were divided into era1 (1990–2007) and era2-rit– (2008–2018), and era2-rit+ (2008–2018) groups. The era2-rit+ group included patients who received single-dose rituximab (200–500 mg) as a desensitization treatment 1–2 weeks before KT.

Results

The 5-year incidence rates of malignant tumors after KT were 3.1%, 4.3%, and 3.5% in the era1, era2-rit–, and era2-rit+ group, respectively. The overall incidence rate of cancer after transplantation among the 3 study groups showed no significant difference (P = 0.340). The overall cancer-related mortality rate was 17.1% (53 of 310). Hepatocellular carcinoma (HCC) had the highest mortality rate (61.5%) and relative risk of cancer-related death (hazard ratio, 8.29; 95% confidence interval, 2.40–28.69; P = 0.001). However, we found no significant association between rituximab and the incidence of any malignancy.

Conclusion

Our results suggest that single-dose rituximab for desensitization may not increase the risk of malignant disease or cancer-related mortality in KT recipients. HCC was associated with the highest risk of cancer-related mortality in an endemic area of HBV infection.

Effect of Different Rituximab Doses on B Cell Count, Anti-A/B Antibody Titer, Graft Function, and Infectious Complications in ABO-Incompatible Renal Transplantation: A Prospective Study

BACKGROUND

ABO-incompatible kidney transplantation (ABOiKT) has been accepted as a viable and cost-effective modality with outcomes comparable to ABO-compatible transplants, but there is a concern regarding higher infectious complications in ABOiKT because of the heightened immunosuppression. The desensitization protocol normally includes antibody removal, B cell depletion by rituximab (RTX), and immunomodulation with intravenous immunoglobulin. Efforts have been made over the years to decrease the dose of RTX in an effort to decrease the infective complications. There is limited literature about the minimum effective dose of RTX, which can cause an effective B cell depletion. This prospective study was designed to correlate the RTX dose with peripheral absolute B cell count, graft function, graft and patient survival, and infective complications.

METHODS

This study included 52 adult ABOiKT recipients with anti-A/B antibody titer up to a maximum of 1:512. The participants were divided into 2 groups of 26 each according to the RTX dosage used: Group A received 100 mg/patient, and Group B received 200 mg/patient. RTX was given 14 days prior to transplant after B cell measurement by flow cytometry. The outcomes were compared after 1 year of follow-up.

RESULTS

Both the dosages effectively depleted the absolute B cell count. Although patient survivals, graft survival, graft function, acute rejection episodes, and post-transplant hospital stay were similar in both groups, infective complications were significantly higher in group B.

CONCLUSION

A low dose (100 mg/patient) of RTX produces effective depletion of B cells while lowering the infective complications in ABOiKT.

Pneumocystis pneumonia occurrence and prophylaxis duration in kidney transplant recipients according to perioperative treatment with rituximab

BACKGROUND

Pneumocystis pneumonia (PCP) is a life-threatening fungal infection that can occur in kidney transplantation (KT) recipients. A growing number of KT recipients are receiving perioperative treatment with rituximab, which is associated with prolonged B-cell depletion and possible risk of PCP occurrence; however, the optimal prophylaxis duration according to rituximab treatment is yet unknown. We compared the occurrence of PCP and the duration of prophylaxis in KT recipients according to rituximab treatment.

METHODS

We retrospectively analyzed 2110 patients who underwent KT between January 2009 and December 2016, who were divided into non-Rituximab group (n = 1588, 75.3%) and rituximab group (n = 522, 24.7%).

RESULTS

In the rituximab group, the estimated number needed to treat (NNT) for prophylaxis prolongation from 6 to 12 months was 29.0 with a relative risk reduction of 90.0%. In the non-rituximab group, the estimated NNT value was 133.3 and the relative risk reduction was 66.4%. Rituximab treatment (hazard ratio (HR) = 3.09; P <  0.01) and acute rejection (HR = 2.19; P = 0.03) were significant risk factors for PCP in multivariate analysis.

CONCLUSIONS

Our results suggest that maintaining PCP prophylaxis for 12 months may be beneficial in KT recipients treated with rituximab for desensitization or acute rejection treatment.

Modulating acute neuroinflammation in intracerebral hemorrhage: the potential promise of currently approved medications for multiple sclerosis

The secondary inflammatory injury following intracerebral hemorrhage (ICH) results in increased morbidity and mortality. White blood cells have been implicated as critical mediators of this inflammatory injury. Currently, no medications have been clinically proven to ameliorate or beneficially modulate inflammation, or to improve outcomes by any mechanism, following ICH. However, other neuroinflammatory conditions, such as multiple sclerosis, have approved pharmacologic therapies that modulate the inflammatory response and minimize the damage caused by inflammatory cells. Thus, there is substantial interest in existing therapies for neuroinflammation and their potential applicability to other acute neurological diseases such as ICH. In this review, we examined the mechanism of action of twelve currently approved medications for multiple sclerosis: alemtuzumab, daclizumab, dimethyl fumarate, fingolimod, glatiramer acetate, interferon beta-1a, interferon beta-1b, mitoxantrone, natalizumab, ocrelizumab, rituximab, teriflunomide. We analyzed the existing literature pertaining to the effects of these medications on various leukocytes and also with emphasis on mechanisms of action during the acute period following initiation of therapy. As a result, we provide a valuable summary of the current body of knowledge regarding these therapies and evidence that supports or refutes their likely promise for treating neuroinflammation following ICH.

Anti-CD20 Blocker Rituximab in Kidney Transplantation

Rituximab is a chimeric anti-CD20 monoclonal protein used in various clinical scenarios in kidney transplant recipients. However, its evidence-based use there remains limited due to lack of controlled studies, limited sample size, short follow-up and poorly defined endpoints. Rituximab is indicated for CD20+ posttransplant lymphoproliferative disorder. It may be beneficial for treating recurrent membranous nephropathy and recurrent allograft antineutrophilic cytoplasmic antibody vasculitis and possibly for recurrent focal segmental glomerulosclerosis. Rituximab, in combination with IVIg/plasmapheresis, appears to decrease antibody level and increase the odds of transplantation in sensitized recipients. The role of Rituximab in ABOi transplant remains unclear, as similar outcomes are achieved without its use. Rituximab is not efficacious in antibody-mediated rejection/chronic antibody-mediated rejection. Strict randomized control trials are necessary to elucidate its true role in these settings.

Feasibility of Monotherapy by Rituximab Without Additional Desensitization in ABO-incompatible Living-Donor Liver Transplantation

BACKGROUND

Rituximab is a cornerstone in the regimens of desensitization for ABO-incompatible living-donor liver transplantation (ABO-i LDLT) that makes this modality an acceptable option for liver transplantation. Plasmapheresis (PP) to reduce anti-ABO antibody titer and local infusion (LI) therapy were practiced as the strategies for desensitization before the application of rituximab and were reported as additional treatments. The aim of this study was to clarify the feasibility of monotherapy by rituximab without any additional desensitization treatments in ABO-i LT.

METHODS

Forty patients receiving ABO-i LDLT with rituximab were enrolled in this retrospective study. The patients were divided into 2 groups: the rituximab with pretransplant PP and posttransplant LI (RPL) group (n = 20) and the rituximab monotherapy (RM) without any additional treatment group (n = 20). The groups were then compared in terms of the rates of patient survival, antibody-mediated rejection (AMR), and infection.

RESULTS

The 1-, 3-, and 5-year patient survival rates were 85%, 85%, and 85% in the RPL group and 89%, 80%, and 80% in the RM group, respectively. There was no significant difference in patient survival between the 2 groups. There were no episodes of AMR in either group. The RM group had a lower rate of fungal and viral infections than the RPL group.

CONCLUSIONS

Pretransplant rituximab without additional treatments yielded satisfactory outcomes comparable to that with additional treatments, such as PP and LI.

Development of antibody mediated rejection shortly after acute cellular rejection in a pediatric kidney transplantation recipient

Acute rejection is a major cause of graft loss in patients with kidney transplantations. However, the appropriate timing for performing a biopsy is often difficult to gauge in a clinical settings. We encountered an 8-year-old boy in whom antibody mediated rejection (AMR) associated with de novo donor-specific antibody (DSA) developed shortly after an episode of type IA acute cellular rejection (ACR). He had received a preemptive ABO-compatible kidney transplantation due to bilateral renal hypoplasia. Type IA ACR developed 2 months after transplantation and was successfully treated with methylprednisolone pulse therapy (MPT) and gusperimus hydrochloride. However, 4 months after transplantation, his serum creatinine level increased again. We decided to perform an additional biopsy despite having done the previous biopsy only a short time ago. Marked infiltration of inflammation cells in the peritubular capillaries (PTCs) with positive C4d staining was observed. AMR associated with de novo DSA with type IB ACR was newly diagnosed because DSA was not detected and the crossmatch test was negative before transplantation. He immediately received two courses of plasma exchange (PE), three courses of MPT, and rituximab. He confessed to non-adherence and underwent a patient education program with his family again. To date, no cases of AMR associated with de novo DSA shortly after ACR have been reported. Our experience lends support to the 'episode biopsy' method in which a biopsy is performed for each episode of serum creatinine increase as recommended by The Kidney Disease: Improving Global Outcomes (KDIGO) Transplant Working Group.

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.

A systematic review of the use of rituximab for desensitization in renal transplantation

BACKGROUND

Rituximab is a B lymphocyte-depleting agent used to treat lymphoma and autoimmune diseases. Recently, it has been used for desensitization therapy in ABO-incompatible and highly sensitized recipients undergoing renal transplantation.

METHODS

A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Four databases and three trial registries were searched for studies comparing rituximab with non-rituximab desensitization protocols. A lack of randomized evidence precluded meta-analysis, and thus a narrative review was conducted.

RESULTS

Forty-five records met the inclusion criteria, relating to 21 individual studies (two randomized controlled trials and 19 retrospective cohort studies). Ten studies investigated the use of rituximab in ABO-incompatible patients; most found no significant differences in patient and graft outcomes when compared most frequently to splenectomy-based protocols. Nine studies of limited quality focused on highly sensitized recipients (positive cross-match, donor-specific antibody, and elevated panel reactive antibody) and demonstrated some benefits in graft survival, acute and chronic rejection, and sensitization levels with rituximab. The remaining two studies combined ABO-incompatible and highly sensitized recipients and found no statistically significant increase in infectious complications with rituximab.

CONCLUSION

Evidence of limited quality was identified to support the use of rituximab desensitization in highly sensitized recipients. Among ABO-incompatible recipients, rituximab was found to be equivalent to splenectomy, indicating that this invasive surgical procedure is not necessary. Further randomized controlled trials are required to better define the efficacy, long-term safety, and optimal dosing regimen of rituximab in this setting.

Comparative nonclinical assessments of the proposed biosimilar PF-05280586 and rituximab (MabThera®)

Comparative nonclinical studies were conducted with the proposed biosimilar PF-05280586 and rituximab-EU (MabThera®). In side-by-side analyses, peptide maps and complement-dependent cytotoxicity assay results were similar. Sexually-mature cynomolgus monkeys were administered PF-05280586 or rituximab-EU as a single dose of 0, 2, 10, or 20 mg/kg on day 1 and observed for 92 days (single-dose study) or as 5 weekly injections of 0 or 20 mg/kg and necropsied on day 30, the day after the 5th dose, or on day 121 (repeat-dose study). The pharmacokinetic and pharmacodynamic profiles for both molecules were similar. Marked depletion of peripheral blood B cells 4 days after dosing was followed by near or complete repletion (single-dose study) or partial repletion (repeat-dose study). In the single-dose study, anti-drug antibodies (ADA) were detected by day 29 in all animals administered PF-05280586 or rituximab-EU and persisted through day 85, the last day tested. In the repeat-dose study, ADA were detected on day 121 in 50% of animals administered PF-05280586 or rituximab-EU. Both molecules were well tolerated at all doses. In all endpoints evaluated, PF-05280586 exhibited similarity to rituximab-EU.

A closer look at rituximab induction on HLA antibody rebound following HLA-incompatible kidney transplantation

Rituximab has been used to increase the efficacy of desensitization protocols for HLA incompatible kidney transplantation, however, controlled comparisons have not been reported. Here we examined 256 post-transplant HLA antibody levels in 25 recipients desensitized with or 25 without rituximab induction, to determine the impact of B cell depletion. We found significantly less HLA antibody rebound in the rituximab-treated patients (7% of donor specific antibodies (DSAs) and 33% of non-DSAs) compared to a control cohort desensitized and transplanted without rituximab (32% DSAs and 55% non-DSAs). The magnitude of the increase was significantly larger among patients who did not receive rituximab. Interestingly, in rituximab treated patients, of the 39 HLA antibodies that increased post-transplant, 34 were specific for HLA mismatches present in previous allografts or pregnancies, implying limited efficacy in memory B cell depletion. Compared to controls, rituximab-treated patients had a significantly greater mean reduction in DSA (−2505 versus −292 mean fluorescence intensity), but a similar rate of DSA persistence (52% in rituximab treated and 40% in non-treated recipients). Thus, rituximab induction in HLA incompatible recipients reduced the incidence and magnitude of HLA antibody rebound, but did not impact DSA elimination, antibody mediated rejection, or 5 year allograft survival when compared to recipients desensitized and transplanted without rituximab.

Prospective data collection of off-label use of rituximab in Australian public hospitals

BACKGROUND

Rituximab is a chimeric, anti-CD20 monoclonal antibody registered for the treatment of B-cell malignancies and refractory rheumatoid arthritis in Australia. In addition to these approved indications, there has been growing interest in the use of off-label rituximab in the management of a variety of diseases.

AIMS

To determine the current usage of off-label rituximab in Australia, we collected nationwide data.

METHODS

Information regarding patients receiving rituximab for off-label indications was prospectively collected for a 6-month period from Australian public hospitals. Data recorded included clinical indication, dosing schedule, previous therapy and efficacy assessment. The level of evidence for the use of rituximab was determined for each off-label indication.

RESULTS

During the 6-month period, a total of 364 instances of off-label rituximab use was recorded in the national database. A total of 63 underlying diagnoses was identified. These were subclassified into haematological disorders (19%), autoimmune connective tissue diseases (12%), vasculitis (12%), neurological disorders (12%), transplant-related uses (12%), haematological malignancies (11%), muscle disorders (8%), renal diseases (6%), dermatological conditions (5%), other conditions (2%) and ocular diseases (1%). Forty percent of these requests were supported only by level 4 evidence of benefit. Data highlighted the non-standardised approaches to drug approval mechanisms, dosing schedules and monitoring for efficacy.

CONCLUSIONS

Off-label rituximab is prescribed for a diverse range of clinical conditions. Determining a safe and effective means of regulating this use within an evidence-based framework remains an ongoing challenge.

Successful treatment of recurrent focal segmental glomerulosclerosis with a low dose rituximab in a kidney transplant recipient

Recurrence of focal segmental glomerulosclerosis (FSGS) is a major therapeutic challenge in kidney transplantation (KT). Although intensive plasmapheresis and high-dose rituximab have been introduced to treat recurrent FSGS, the most effective dosage and regimen of rituximab have not been determined. Herein we reported the first case of successful treatment of recurrent FSGS with a low-dose rituximab. The patient showed marked proteinuria (3.5 g/d) and oliguria 2 d after KT. Two courses of plasmapheresis and immunoglobulin were applied to the patient, however, nephrotic range proteinuria persisted and creatinine level increased to 3.56 mg/dL. Five months post-transplant, the patient received injection with only one dose of rituximab 100 mg, without further plasmapheresis, which resulted in immediate reduction of serum creatinine and full remission of proteinuria during the following 18 months. This case suggested that recurrent FSGS, which frequently relapses after plasmapheresis, could be treated successfully with a low-dose rituximab even without plasmapheresis.

Effects of Rituximab on the Development of Viral and Fungal Infections in Renal Transplant Recipients

Background. Rituximab is becoming increasingly utilized in renal transplant recipients; however, its association with infections remains unclear. Methods. We reviewed the incidence of viral and fungal infections in kidney transplant recipients treated with () or without () rituximab (RTX) in addition to standard immunosuppression. Results. Infections occurred in 134 (30%) patients, with a greater proportion in RTX versus no RTX patients (47% versus 28%; ). Viral infections occurred in 44% and 27% of RTX and no RTX patients, respectively (). This was largely driven by the frequency of BK viremia and noncytomegalovirus/non-BK viruses in RTX patients (27% versus 13% () and 15% versus 2% (), resp.). Fungal infections also occurred more often in RTX patients (11% versus 3 %; ). Multivariate analysis revealed deceased donor recipient (odds ratio = 2.5; ) and rituximab exposure (odds ratio = 2.2; ) as independent risk factors for infection. Older patients, deceased donor recipients, those on dialysis longer, and those with delayed graft function tended to be at a greater risk for infections following rituximab. Conclusions. Rituximab is associated with an increased incidence of viral and fungal infections in kidney transplantation. Additional preventative measures and/or monitoring infectious complications may be warranted in those receiving rituximab.

Rituximab prevents an anamnestic response in patients with cryptic sensitization to HLA

BACKGROUND

Some patients sensitized to HLA antigens do not have antibody present in serum specimens that are available before transplantation. However, such patients are at risk for an anamnestic response resulting from a proinflammatory response to the trauma of transplant surgery. Quantifying HLA-specific B cells provides a way to identify these patients and provide treatment to prevent an anamnestic response.

METHODS

B cells were isolated before transplantation from 59 patients, 20 of whom were treated with rituximab at the time of transplantation. Ninety-nine tests were performed to quantify HLA-specific B cells by staining with HLA tetramers. Patients were considered sensitized or nonsensitized based on the frequencies of HLA-specific B cells. Pretransplantation and posttransplantation sera were tested for the detection of antibody specific for the tetramer antigen.

RESULTS

Of the 24 cases where patients were considered sensitized to HLA antigens but did not have antibody before transplantation, no posttransplantation antibody to the tetramer antigen was detected in 10 cases when patients were treated with rituximab, but antibody was detected in 13 of 16 cases when there was no rituximab treatment (P=0.00006). The mean frequencies of B cells specific for HLA-B7 were the same in rituximab-treated patients who did not make antibody and in nontreated patients who did make antibody (6.0% vs. 5.7%; P=0.8).

CONCLUSIONS

Elimination of peripheral HLA-specific B cells in patients who are sensitized to HLA antigens but lacking detectable antibody abrogates an anamnestic response.

ABO-incompatible kidney transplantation

PURPOSE OF REVIEW

A dramatic shortage of available organs around the world encouraged attempts to cross previously forbidden immunological boundaries in kidney transplantation. This review focuses on the recent results of ABO-incompatible kidney transplantation.

RECENT FINDINGS

The outcome of ABO-incompatible kidney transplantation in terms of patient and graft survival is comparable to ABO-compatible transplantation for adult and pediatric recipients. Splenectomy has been replaced by the B-cell-depleting agent rituximab to avoid isoagglutinin titer rebound, prevent antibody-mediated rejection, and improve graft survival. However, the risk for infections may be increased and warrants caution. Corticosteroids remain a necessary component of any ABO-incompatible protocol; early as well as late steroid withdrawal may bear an enhanced risk for acute rejection and should only be performed with careful follow-up including protocol biopsies. The few studies that have long-term outcomes using protocol biopsies have characterized a state of accommodation by up-regulation of complement inhibitors, down-regulation of A/B antigens, and establishment of endothelial chimerism over time.

SUMMARY

The experience accumulated around the world indicates that ABO-incompatible kidney transplantation is well tolerated and effective in adults and in children, and it represents an important step forward in expanding the living donor pool. Further understanding of ABO-incompatible graft accommodation may have broader implication also for human leukocyte antigen-sensitized allograft recipients.

Rationale and design of the RIACT-study: a multi-center placebo controlled double blind study to test the efficacy of RItuximab in Acute Cellular tubulointerstitial rejection with B-cell infiltrates in renal Transplant patients: study protocol for a randomized controlled trial

BACKGROUND

Acute kidney allograft rejection is a major cause for declining graft function and has a negative impact on the long-term graft survival. The majority (90%) of acute rejections are T-cell mediated and, therefore, the anti-rejection therapy targets T-cell-mediated mechanisms of the rejection process. However, there is increasing evidence that intragraft B-cells are also important in the T-cell-mediated rejections. First, a significant proportion of patients with acute T-cell-mediated rejection have B-cells present in the infiltrates. Second, the outcome of these patients is inferior, which has been related to an inferior response to the conventional anti-rejection therapy. Third, treatment of these patients with an anti-CD20 antibody (rituximab) improves the allograft outcome as reported in single case observations and in one small study. Despite the promise of these observations, solid evidence is required before incorporating this treatment option into a general treatment recommendation.

METHODS/DESIGN

The RIACT study is designed as a randomized, double-blind, placebo-controlled, parallel group multicenter Phase III study. The study examines whether rituximab, in addition to the standard treatment with steroid-boli, leads to an improved one-year kidney allograft function, compared to the standard treatment alone in patients with acute T-cell mediated tubulointerstitial rejection and significant B-cell infiltrates in their biopsies. A total of 180 patients will be recruited.

DISCUSSION

It is important to clarify the relevance of anti-B cell targeting in T-cell mediated rejection and answer the question whether this novel concept should be incorporated in the conventional anti-rejection therapy.

TRIAL REGISTRATION

Clinical trials gov. number: NCT01117662.

Successful kidney transplantation after desensitization using plasmapheresis, low-dose intravenous immunoglobulin, and rituximab in highly sensitized patients: a single-center experience

BACKGROUND

For many highly allosensitized renal transplant candidates, an acceptable donor is never identified, and the patient remains on dialysis indefinitely. In an attempt to ameliorate this situation, several desensitization protocols have been developed that permit positive-crossmatch kidney transplantation. Here, we report our experiences of living donor kidney transplantation in highly sensitized patients.

METHODS

We treated seven highly sensitized patients between March 2003 and September 2009. All patients underwent desensitization using pretransplant plasmapheresis (PP) and low-dose intravenous immunoglobulin (IVIG; 100 mg/kg) with rituximab (six patients) or without rituximab (one patient). Demographics, immunologic characteristics of patients, allograft function, acute rejection (AR) episodes, survival, and adverse events were evaluated.

RESULTS

Seven patients with positive-crossmatch tests or high levels of panel-reactive antibody (PRA) were included. Their mean age was 51.4 ± 3.3 years. The average number of human leukocyte antigen mismatchs was 3.4 ± 0.5. The mean percent PRA was 41.7% ± 6.1%. Six patients were crossmatch-positive, and one patient was crossmatch-negative but had high PRA levels. The mean follow-up period was 33.2 ± 5.4 months after transplantation. The all patients showed no AR episodes for follow-up period, and the patient and graft survival rates were 100%. The mean serum creatinine concentration at last follow-up was 0.92 ± 0.11 mg/dL.

CONCLUSIONS

Our experiences suggest that the combination of PP and low-dose IVIG with or without rituximab may prove effective as a desensitization regimen for positive-crossmatch and/or highly sensitized living donor renal transplant recipients. Further investigations are needed to evaluate the long-term clinical efficacy and safety of this approach.

Antibody-mediated rejection: pathogenesis, prevention, treatment, and outcomes

Antibody-mediated rejection (AMR) is a major cause of late kidney transplant failure. It is important to have an understanding of human-leukocyte antigen (HLA) typing including well-designed studies to determine anti-MHC-class-I-related chain A (MICA) and antibody rejection pathogenesis. This can allow for more specific diagnosis and treatment which may improve long-term graft function. HLA-specific antibody detection prior to transplantation allows one to help determine the risk for AMR while detection of DSA along with a biopsy confirms it. It is now appreciated that biopsy for AMR does not have to include diffuse C4d, but does require a closer look at peritubular capillary microvasculature. Although plasmapheresis (PP) is effective in removing alloantibodies (DSAs) from the circulation, rebound synthesis of alloantibodies can occur. Splenectomy is used in desensitization protocols for ABO incompatible transplants as well as being found to treat AMR refractory to conventional treatment. Also used are agents targeted for plasma cells, B cells, and the complement cascade which are bortezomib rituximab and eculizumab, respectively.

Inotuzumab ozogamicin murine analog-mediated B-cell depletion reduces anti-islet allo- and autoimmune responses

B cells participate in the priming of the allo- and autoimmune responses, and their depletion can thus be advantageous for islet transplantation. Herein, we provide an extensive study of the effect of B-cell depletion in murine models of islet transplantation. Islet transplantation was performed in hyperglycemic B-cell-deficient(μMT) mice, in a purely alloimmune setting (BALB/c into hyperglycemic C57BL/6), in a purely autoimmune setting (NOD.SCID into hyperglycemic NOD), and in a mixed allo-/autoimmune setting (BALB/c into hyperglycemic NOD). Inotuzumab ozogamicin murine analog (anti-CD22 monoclonal antibody conjugated with calicheamicin [anti-CD22/cal]) efficiently depleted B cells in all three models of islet transplantation examined. Islet graft survival was significantly prolonged in B-cell-depleted mice compared with control groups in transplants of islets from BALB/c into C57BL/6 (mean survival time [MST]: 16.5 vs. 12.0 days; P = 0.004), from NOD.SCID into NOD (MST: 23.5 vs. 14.0 days; P = 0.03), and from BALB/c into NOD (MST: 12.0 vs. 5.5 days; P = 0.003). In the BALB/c into B-cell-deficient mice model, islet survival was prolonged as well (MST: μMT = 32.5 vs. WT = 14 days; P = 0.002). Pathology revealed reduced CD3(+) cell islet infiltration and confirmed the absence of B cells in treated mice. Mechanistically, effector T cells were reduced in number, concomitant with a peripheral Th2 profile skewing and ex vivo recipient hyporesponsiveness toward donor-derived antigen as well as islet autoantigens. Finally, an anti-CD22/cal and CTLA4-Ig-based combination therapy displayed remarkable prolongation of graft survival in the stringent model of islet transplantation (BALB/c into NOD). Anti-CD22/cal-mediated B-cell depletion promotes the reduction of the anti-islet immune response in various models of islet transplantation.

Humoral immunity and antibody-mediated rejection in solid organ transplantation

The humoral arm of the immune system provides robust protection against extracellular pathogens via the production of antibody molecules that neutralize or facilitate the destruction of microorganisms. However, the humoral immune system also provides a significant barrier to solid organ transplantation due to the antibody-mediated recognition of non-self proteins and carbohydrates expressed on transplanted organs. Historically, the presence of donor-specific antibodies (DSA) that recognize donor HLA molecules, incompatible ABO blood group antigens and other endothelial or xenogeneic antigens was considered a contraindication to transplantation. However, recent advances in antibody testing and immunosuppressive therapies have made it possible to cross certain antibody barriers successfully. In this article, we review our current understanding of antibody-mediated processes in solid organ transplantation and discuss the clinically available treatment options for preventing and treating antibody-mediated rejection.

Treatment options and strategies for antibody mediated rejection after renal transplantation

Antibody mediated rejection is a significant clinical problem encountered in a subset of renal transplant recipients. This type of rejection has a variable pathogenesis from the presence of donor specific antibodies with no overt disease to immediate hyperacute rejection and many variations between. Antibody mediated rejection is more common in human leukocyte antigen sensitized patients. In general, transplant graft survival after antibody mediated rejection is jeopardized, with less than 50% graft survival 5 years after this diagnosis. A variety of agents have been utilized singly and in combinations to treat antibody mediated rejection with differing results and significant research efforts are being placed on developing new targets for intervention. These same agents have been used in desensitization protocols with some success. In this review, we describe the biology of antibody mediated rejection, review the available agents to treat this form of rejection, and highlight areas of ongoing and future research into this difficult clinical problem.

ABO blood group incompatibility: a diminishing barrier to successful kidney transplantation?

Blood type-incompatible transplantation has gained wide acceptance over the last decade. This is largely the result of B-cell-directed therapies aimed at modulating anti-blood group antibodies, which were the cause of the poor outcomes originally seen. Now rituximab (anti-CD20 and anti-B cell) has largely replaced splenectomy in preconditioning protocols, allowing for the wider implementation of ABO-incompatible transplants. Plasma exchange followed by intravenous immunoglobulin is also critical for the success of ABO-incompatible transplants. In this article, we describe the important contributions immunomodulatory drugs and antibody reduction therapies have made in achieving excellent outcomes in what was once an impenetrable barrier to transplantation.

Antibody-mediated rejection in kidney transplantation: an update

INTRODUCTION

Acute antibody-mediated rejection (AMR) in renal-transplant recipients is generally less responsive to conventional antirejection therapy and has a worse prognosis than acute cellular rejection.

AREAS COVERED

This review provides a broad understanding of the pathogenesis of AMR, recent advances in its therapy, and future directions. Conventional therapeutic approaches to AMR have minimal impact on mature plasma cells, the major source of antibody production. Emerging therapies include bortezomib, a proteasome inhibitor, and eculizumab, an anti-C5 antibody. In several reports, bortezomib therapy resulted in prompt reversal of rejection, decreased titers of donor-specific antibodies (DSA), and improved renal allograft function. Eculizumab also reversed AMR and prevented its development in patients with high post-transplantation DSA levels.

EXPERT OPINION

Despite the small sample size and lack of controls, these studies are encouraging, and although larger studies and long-term follow-up are needed, bortezomib and eculizumab may play a major future role in AMR therapy.

Advances in diagnosing and managing antibody-mediated rejection

Antibody-mediated rejection (AMR) is a unique, significant, and often severe form of allograft rejection that is not amenable to treatment with standard immunosuppressive medications. Significant advances have occurred in our ability to predict patients at risk for, and to diagnose, AMR. These advances include the development of newer anti-human leukocyte antigen (HLA)-antibody detection techniques and assays for non-HLA antibodies associated with AMR. The pathophysiology of AMR suggests a prime role for antibodies, B cells and plasma cells, but other effector molecules, especially the complement system, point to potential targets that could modify the AMR process. An emerging and potentially larger problem is the development of chronic AMR (CAMR) resulting from de novo donor-specific anti-HLA antibodies (DSA) that emerge more than 100 days posttransplantation. Therapeutic options include: (1) High-dose intravenously administered immunoglobulin (IVIG), which has many potential benefits. (2) The use of IVIG+rituximab (anti-CD20, anti-B cell). (3) The combination of plasmapheresis (PP)+low-dose IVIG with or without rituximab. Data support the efficacy of all of the above approaches. Newer approaches to treating AMR include using the proteosome inhibitor (bortezomib), which induces apoptosis in plasma cells, and eculizumab (anti-C5, anticomplement monoclonal antibody).

Dual living donor liver transplantation with ABO-incompatible and ABO-compatible grafts to overcome small-for-size graft and ABO blood group barrier

ABO blood group compatibility has been regarded as an essential prerequisite for successful adult living donor liver transplantation (LDLT). Novel strategies for overcoming the ABO blood group barrier, however, have markedly improved the results of ABO-incompatible (ABOi) LDLT. We describe our strategies for dual graft LDLT to cope with ABO-incompatibility and small-for-size graft syndrome in 3 patients who underwent dual graft LDLT with ABOi and ABO-compatible (ABOc) grafts. One patient received a modified right lobe graft from an ABOi living donor and a left lateral section graft from an ABOc deceased donor, whereas the other 2 patients received 2 left lobe or left lateral section grafts from ABOi and ABOc living donors. To overcome the ABO-blood barrier, each patient was treated with preoperative anti-CD20 antibody (rituximab 375 mg/m(2)), perioperative plasma exchange, and hepatic arterial infusion. All 3 patients were males, of mean age 47.7 years (range, 40 approximately 52 years) and mean Model for End-Stage Liver Disease score 12.3 (range, 9 approximately 15). The mean graft-to-recipient weight ratio was 0.99%. All patients remain alive after a mean follow-up period of 9.5 months (range, 8.0 approximately 10.7 months). All 6 grafts have functioned normally. There were no episodes of antibody-mediated rejection or biliary complication. Dual LDLT with ABOi and ABOc grafts can be a feasible solution for simultaneously overcoming both the ABO blood group barrier and small-for-size graft syndrome.

Use of antibody induction in pediatric renal transplantation

PURPOSE OF REVIEW

The present review provides an update on the recent literature documenting the use of antibody induction in pediatric transplantation.

RECENT FINDINGS

The use of antibody induction has been increasing as it has been considered to be an important component of steroid-avoidance protocols following pediatric renal transplantation. According to registry data, anti-interleukin-2R monoclonal antibodies are the predominant agents being used, with slightly more patients receiving basiliximab than daclizumab. Using antibody induction, steroid avoidance is possible while maintaining rejection rates of less than 10%. Preliminary data are appearing, in which both steroid elimination and calcineurin reduction are possible. Concerns, however, are being raised about the risk of overimmunosuppression, in particular increased rates of polyoma virus and lymphoma.

SUMMARY

Antibody induction is firmly entrenched within the pediatric renal transplant community. There is an ongoing evolution of the types of antibodies being used. The ultimate answer for efficacy and safety will require larger samples and prospective studies.

Successful renal transplantation with desensitization in highly sensitized patients: a single center experience

Intravenous immunoglobulin (IVIG) and/or plasmapheresis (PP) are effective in preventing antibody-mediated rejection (AMR) of kidney allografts, but AMR is still a problem. This study reports our experience in living donor renal transplantation in highly sensitized patients. Ten patients with positive crossmatch tests or high levels of panel-reactive antibody (PRA) were included. Eight patients were desensitized with pretransplant PP and low dose IVIG, and two were additionally treated with rituximab. Allograft function, number of acute rejection (AR) episodes, protocol biopsy findings, and the presence of donor-specific antibody (DSA) were evaluated. With PP/IVIG, six out of eight patients showed good graft function without AR episodes. Protocol biopsies revealed no evidence of tissue injury or C4d deposits. Of two patients with AR, one was successfully treated with PP/IVIG, but the other lost graft function due to de novo production of DSA. Thereafter, rituximab was added to PP/IVIG in two cases. Rituximab gradually decreased PRA levels and the percentage of peripheral CD20+ cells. DSA was undetectable and protocol biopsy showed no C4d deposits. The graft function was stable and there were no AR episodes. Conclusively, desensitization using PP/IVIG with or without rituximab increases the likelihood of successful living donor renal transplantation in sensitized recipients.

A randomized, prospective trial of rituximab for acute rejection in pediatric renal transplantation

We report 1-year outcomes of a randomized study of Rituximab versus standard-of-care immunosuppression (Thymoglobulin and/or pulse steroids) for treatment of biopsy confirmed, acute transplant rejection with B-cell infiltrates, in 20 consecutive recipients (2-23 years). Graft biopsies, with Banff and CADI scores, CD20 and C4d stains, were performed at rejection and 1 and 6 months later. Peripheral blood CMV, EBV and BK viral loads, graft function, DSA, immunoglobulins, serum humanized antichimeric antibody (HACA) and Rituximab, and lymphocyte counts were monitored until 1 year posttreatment. Rituximab infusions were given with a high index of safety without HACA development and increased infections complications. Rituximab therapy resulted in complete tissue B-cell depletion and rapid peripheral B-cell depletion. Peripheral CD19 cells recovered at a mean time of approximately 12 months. There were some benefits for the recovery of graft function (p = 0.026) and improvement of biopsy rejection scores at both the 1- (p = 0.0003) and 6-month (p < 0.0001) follow-up biopsies. Reappearance of C4d deposition was not seen on follow-up biopsies after Rituximab therapy, but was seen in 30% of control patients. There was no change in DSA in either group, independent of rejection resolution. This study reports safety and suggests further investigation of Rituximab as an adjunctive treatment for B-cell-mediated graft rejection.

Targeting CD22 reprograms B-cells and reverses autoimmune diabetes

OBJECTIVES

To investigate a B-cell-depleting strategy to reverse diabetes in naïve NOD mice.

RESEARCH DESIGN AND METHODS

We targeted the CD22 receptor on B-cells of naïve NOD mice to deplete and reprogram B-cells to effectively reverse autoimmune diabetes.

RESULTS

Anti-CD22/cal monoclonal antibody (mAb) therapy resulted in early and prolonged B-cell depletion and delayed disease in pre-diabetic mice. Importantly, when new-onset hyperglycemic mice were treated with the anti-CD22/cal mAb, 100% of B-cell-depleted mice became normoglycemic by 2 days, and 70% of them maintained a state of long-term normoglycemia. Early therapy after onset of hyperglycemia and complete B-cell depletion are essential for optimal efficacy. Treated mice showed an increase in percentage of regulatory T-cells in islets and pancreatic lymph nodes and a diminished immune response to islet peptides in vitro. Transcriptome analysis of reemerging B-cells showed significant changes of a set of proinflammatory genes. Functionally, reemerging B-cells failed to present autoantigen and prevented diabetes when cotransferred with autoreactive CD4(+) T-cells into NOD.SCID hosts.

CONCLUSIONS

Targeting CD22 depletes and reprograms B-cells and reverses autoimmune diabetes, thereby providing a blueprint for development of novel therapies to cure autoimmune diabetes.