Efficacy and Safety of Tocilizumab in the Treatment of Acute Active Antibody-mediated Rejection in Kidney Transplant Recipients

Pushing the Survival Bar Higher: Two Decades of Innovation in Lung Transplantation

Survival after lung transplantation has significantly improved during the last two decades. The refinement of the already existing extracorporeal life support (ECLS) systems, such as extracorporeal membrane oxygenation (ECMO), and the introduction of new techniques for donor lung optimization, such as ex vivo lung perfusion (EVLP), have allowed the extension of transplant indication to patients with end-stage lung failure after acute respiratory distress syndrome (ARDS) and the expansion of the donor organ pool, due to the better evaluation and optimization of extended-criteria donor (ECD) lungs and of donors after circulatory death (DCD). The close monitoring of anti-HLA donor-specific antibodies (DSAs) has allowed the early recognition of pulmonary antibody-mediated rejection (AMR), which requires a completely different treatment and has a worse prognosis than acute cellular rejection (ACR). As such, the standardization of patient selection and post-transplant management has significantly contributed to this positive trend, especially at high-volume centers. This review focuses on lung transplantation after ARDS, on the role of EVLP in lung donor expansion, on ECMO as a principal cardiopulmonary support system in lung transplantation, and on the diagnosis and therapy of pulmonary AMR.

A Population Pharmacokinetic Model of Tocilizumab in Kidney Transplant Patients Treated for Chronic Active Antibody-Mediated Rejection: Comparison of Plasma Exposure Between Intravenous and Subcutaneous Administration Schemes

BACKGROUND

Tocilizumab prevents the clinical worsening of chronic active antibody-mediated rejection (CAAMR) in kidney transplant recipients. Following a global shortage of the intravenous pharmaceutical form in 2022, patients were switched from monthly intravenous administration of 8 mg/kg to weekly subcutaneous injection of 162 mg, raising the question of bioequivalence between these schemes of administration.

AIMS

We aimed to compare the areas under the curve (AUC) of tocilizumab in virtual simulations of populations treated with the two administration schemes and to identify the covariates that could contribute to pharmacokinetic variability of tocilizumab in kidney transplant patients with CAAMR who received tocilizumab as salvage treatment.

METHODS

This retrospective monocentric study included 43 kidney transplant patients (202 tocilizumab concentrations) with CAAMR treated with intravenous or subcutaneous tocilizumab between December 2020 and January 2023. We developed a population pharmacokinetic model using nonlinear mixed effects modeling and identified the covariates that could contribute to tocilizumab AUC variability. Monte Carlo simulations were then performed to assess the subcutaneous and intravenous tocilizumab AUC for 0-28 days (M1), 56-84 days (M3), 140-168 days (M6), and 308-336 days (M12). Bioequivalence was defined by SC/IV AUC geometric mean ratios (GMRs) between 0.80 and 1.25.

RESULTS

A two-compartment model with parallel linear and nonlinear elimination best described the concentration-time data. Significant covariates for tocilizumab clearance were body weight, urinary albumin-to-creatinine ratio (ACR), and inflammation status [C-reactive protein (CRP) ≥ 5 mg/L]. The GMR values and their 90% confidence intervals at M3, M6, and M12 were within the 0.8-1.25 margin for equivalence. Conversely, the 90% prediction intervals of the GMR were much wider than the 90% confidence intervals and did not fall within 0.8 and 1.25.

CONCLUSIONS

From month 3 of treatment, the subcutaneous and intravenous tocilizumab administration schemes provided average bioequivalent pharmacokinetic exposure at the population level but not at the individual level. Body weight, inflammation, ACR, and administration scheme should be considered to personalize the dose of tocilizumab for patients with CAAMR. Further studies are required to determine the target of tocilizumab exposure in kidney transplant patients with CAAMR.

Granulomatous Tubulointerstitial Nephritis in a Kidney Allograft: Treatment with Interleukin-6 Receptor Antagonist Stabilises Kidney Function

Granulomatous tubulointerstitial nephritis (GTIN) attributed to early onset sarcoidosis is an ultrarare finding in an allograft kidney biopsy. We present the case of a young man with allograft dysfunction who had GTIN upon biopsy. We performed a thorough case review based on recovered records from early childhood and reassessed genetic testing results. We revised his underlying diagnosis from cryopyrin-associated periodic syndrome to early-onset sarcoidosis with wild-type NOD2 and established a rationale to use the interleukin-6 (IL-6) receptor blocker tocilizumab (TCZ). This suppressed his inflammatory disease and stabilised kidney function. We performed a literature review related to the emerging role of IL-6 pathway blockade in kidney transplantation. We identified 18 reports with 417 unique patients treated with TCZ for indications including HLA-desensitisation, transplant immunosuppression induction, treatment of chronic antibody-mediated rejection, and treatment of subclinical rejection. Both TCZ and the direct IL-6 inhibitor clazakizumab are being studied in ongoing randomised control trials.

IL-6 inhibition prevents costimulation blockade-resistant allograft rejection in T cell-depleted recipients by promoting intragraft immune regulation in mice

The efficacy of costimulation blockade with CTLA4-Ig (belatacept) in transplantation is limited due to T cell-mediated rejection, which also persists after induction with anti-thymocyte globulin (ATG). Here, we investigate why ATG fails to prevent costimulation blockade-resistant rejection and how this barrier can be overcome. ATG did not prevent graft rejection in a murine heart transplant model of CTLA4-Ig therapy and induced a pro-inflammatory cytokine environment. While ATG improved the balance between regulatory T cells (Treg) and effector T cells in the spleen, it had no such effect within cardiac allografts. Neutralizing IL-6 alleviated graft inflammation, increased intragraft Treg frequencies, and enhanced intragraft IL-10 and Th2-cytokine expression. IL-6 blockade together with ATG allowed CTLA4-Ig therapy to achieve long-term, rejection-free heart allograft survival. This beneficial effect was abolished upon Treg depletion. Combining ATG with IL-6 blockade prevents costimulation blockade-resistant rejection, thereby eliminating a major impediment to clinical use of costimulation blockers in transplantation.

Translating B cell immunology to the treatment of antibody-mediated allograft rejection

Antibody-mediated rejection (AMR), including chronic AMR (cAMR), causes ~50% of kidney allograft losses each year. Despite attempts to develop well-tolerated and effective therapeutics for the management of AMR, to date, none has obtained FDA approval, thereby highlighting an urgent unmet medical need. Discoveries over the past decade from basic, translational and clinical studies of transplant recipients have provided a foundation for developing novel therapeutic approaches to preventing and treating AMR and cAMR. These interventions are aimed at reducing donor-specific antibody levels, decreasing graft injury and fibrosis, and preserving kidney function. Innovative approaches emerging from basic science findings include targeting interactions between alloreactive T cells and B cells, and depleting alloreactive memory B cells, as well as donor-specific antibody-producing plasmablasts and plasma cells. Therapies aimed at reducing the cytotoxic antibody effector functions mediated by natural killer cells and the complement system, and their associated pro-inflammatory cytokines, are also undergoing evaluation. The complexity of the pathogenesis of AMR and cAMR suggest that multiple approaches will probably be required to treat these disease processes effectively. Definitive answers await results from large, double-blind, multicentre, randomized controlled clinical trials.

The Effect of Splenic Irradiation on Mean Fluorescence Intensity Values of HLA Antibody in Presensitized Patients Waiting for Kidney Transplantation

To explore the desensitization treatment of patients waiting for kidney transplantation, this article comparative analysis of the effect of splenic irradiation on mean fluorescence intensity (MFI) values of HLA antibodies of 4 presensitized patients. After splenic irradiation, the mean MFI values of HLA-I antibody in 4 patients all decreased (P ≤ .001, P ≤ .001, P ≤ .001, P ≤ .001), and 3 patients had a decrease in intensity level (P ≤ .001, P = .001, P ≤ .001); as for HLA-II antibody, the mean MFI values in 3 patients also decreased (P ≤ .001, P = .025, P = .016), 1 patient had a decrease in intensity level (P ≤ .001) and the other 2 cases had no significant changes (P = 1.000, P = .564). On the other hand, splenic irradiation reduces MFI values in different levels of HLA antibody. So, splenic irradiation can reduce the MFI values of HLA antibodies.

Early Exposure of Kidney Transplant Recipients with Chronic Antibody-Mediated Rejection to Tocilizumab-A Preliminary Study

Tocilizumab prevents clinical worsening of chronic antibody-mediated rejection (CAMR) of kidney transplant recipients. Optimization of this treatment is necessary. We identified the determinants of early tocilizumab exposure (within the first three months) and investigated the relationship between early plasma tocilizumab exposure and graft function. Patients with CAMR who started treatment with tocilizumab were retrospectively included. Demographic, clinical, and biological determinants of the tocilizumab trough concentration (Cmin) were studied using a linear mixed effect model, and the association between early exposure to tocilizumab (expressed as the sum of Cmin over the three first months (M) of treatment (ΣCmin)) and the urinary albumin-to-creatinine ratio (ACR) determined at M3 and M6 were investigated. Urinary tocilizumab was also measured in seven additional patients. Seventeen patients with 51 tocilizumab Cmin determinations were included. In the multivariate analysis, the ACR and time after tocilizumab initiation were independently associated with the tocilizumab Cmin. The ΣCmin was significantly lower (p = 0.014) for patients with an ACR > 30 mg/mmol at M3 and M6 than for patients with an ACR < 30 mg/mmol. Tocilizumab was detected in urine in only 1/7 patients. This study is the first to suggest that early exposure to tocilizumab may be associated with macroalbuminuria within the first six months in CAMR patients.

Emerging Therapies for Antibody-Mediated Rejection in Kidney Transplantation

Despite the advances in immunosuppressive medications, antibody-mediated rejection (AMR) continues to be a major cause of kidney allograft failure and remains a barrier to improving long-term allograft survival. Recently, there have been significant advances in the understanding of the pathophysiological process of AMR, along with the development of new therapeutic options. Additionally, surveillance protocols with donor-derived cell-free DNA and gene profile testing have been established, leading to the early detection of AMR. A multitude of clinical trials are ongoing, opening numerous opportunities for improving outcome in kidney transplant recipients. In this brief review, we discuss the emerging therapies for managing both active and chronic active AMR and highlight the ongoing clinical trials.

Novel therapies for treatment of antibody-mediated rejection of the kidney

PURPOSE OF REVIEW

We aim to discuss current literature on novel therapies for antibody-mediated rejection (AMR) in kidney transplantation with a focus on chronic AMR.

RECENT FINDINGS

IL-6/IL-6 receptor blockers appear promising in the treatment of chronic AMR. Blocking this pathway was shown to reduce human leucocyte antigen-antibodies, improve histologic inflammation and increase T-regulatory cells. Based on experience in desensitization, IgG degrading endopeptidase, imlifidase, could be effective in AMR. There have been case reports describing the successful use of plasma cell/natural killer-cell-directed anti-CD38 antibody in the treatment of AMR. Off-target effects have been noted and strategies to mitigate these will be needed when using these agents. Complement inhibitors could be an effective add-on strategy to antibody-depleting therapies but their role in AMR needs to be better defined. Combining proteasome inhibitors and costimulation blockers has shown encouraging results in the prevention of AMR in animal models and is now being investigated in humans. Other novel strategies such as Fc neonatal receptor blockers which inhibit the recycling of pathogenic IgG and bispecific antibodies against B-cell maturation antigen/CD3+ T cells warrant further investigation.

SUMMARY

There are now a number of emerging therapies with varied targets and mechanism(s) of action that hold promise in the management of AMR and improving allograft survival.

Updated management for antibody-mediated rejection: opportunity to prolong kidney allograft survival

PURPOSE OF REVIEW

Antibody-mediated rejection (ABMR) is an important barrier to achieve long-term kidney allograft survival. Human leukocyte antibody (HLA)-incompatibility and ABO-incompatibility are the two main mechanisms of ABMR. Nevertheless, the advances in managing ABMR have changed the paradigm for kidney transplantation. This review aimed to emphasize the HLA-incompatibility and ABO-incompatibility kidney transplant and update the management of ABMR.

RECENT FINDINGS

HLA-incompatibility kidney transplantation is a strong risk factor for ABMR. Donor-specific antibody (DSA) is a surrogate biomarker that prevents long-term allograft survival. The standard treatment for ABMR has unfavorable results. New drugs that target the B cell are a promising approach to treat ABMR. In the past, ABO-incompatibility kidney donor was an absolute contraindication but now, it is widely accepted as an alternative organ resource. The advancement of ABO antibody removal and B-cell depletion therapy has been successfully developed. ABO isoagglutination remains the main biomarker for monitoring ABMR during the transplantation process. C4d staining without inflammation of the kidney allograft is the marker for the accommodation process.

SUMMARY

With the shortage of organ donors, transplant experts have expanded the organ resources and learned how to overcome the immunological barriers by using novel biomarkers and developing new treatments that support long-term graft survival.

Impact of interleukin-6 on T cells in kidney transplant recipients

Interleukin-6 (IL-6), a multifunctional proinflammatory cytokine, plays a key role in T cell activation, survival, and differentiation. Acting as a switch that induces the differentiation of naïve T cells into Th17 cells and inhibits their development into regulatory T cells, IL-6 promotes rejection and abrogates tolerance. Therapies that target IL-6 signaling include antibodies to IL-6 and the IL-6 receptor and inhibitors of janus kinases; several of these therapeutics have demonstrated robust clinical efficacy in autoimmune and inflammatory diseases. Clinical trials of IL-6 inhibition in kidney transplantation have focused primarily on its effects on B cells, plasma cells, and HLA antibodies. In this review, we summarize the impact of IL-6 on T cells in experimental models of transplant and describe the effects of IL-6 inhibition on the T cell compartment in kidney transplant recipients.

Importance of IL-6 inhibition in prevention and treatment of antibody-mediated rejection in kidney allografts

Interleukin-6 (IL-6) is a cytokine critical for innate and adaptive immune responses. However, persistent expression of high levels of IL-6 are associated with a number of pathologic conditions including autoimmune diseases and capillary leak syndrome. Importantly, in kidney transplant patients, IL-6 may play a role in mediation of cell-mediated rejection (CMR) and antibody-mediated rejection (AMR). This is likely due to the importance of IL-6 in stimulating B cell responses with pathogenic donor-specific antibody (DSA) generation and stimulation of T effector cell responses while inhibiting T regulatory cells. Data from preliminary clinical trials and clinical observations show that tocilizumab (anti-IL-6R) and clazakizumab (anti-IL-6) may have promise in treatment of CMR, AMR and chronic (cAMR). This has led to a phase 3 placebo, randomized clinical trial of clazakizumab for treatment of cAMR, a condition for which there is currently no treatment. The identification of IL-6 production in vascular endothelia cells after alloimmune activation reveals another potential pathway for vasculitis as endothelia cell IL-6 may stimulate immune cell responses that are potentially inhibitable with anti-IL-6/IL-6R treatment. Importantly, anti-IL-6/IL-6R treatments have shown the ability to induce Treg and Breg cells in vivo which may have potential importance for prevention and treatment of DSA development and allograft rejection.

Targeting IL-6 to prevent cardiac allograft rejection

Outcomes following heart transplantation remain suboptimal with acute and chronic rejection being major contributors to poor long-term survival. IL-6 is increasingly recognized as a critical pro-inflammatory cytokine involved in allograft injury and has been shown to play a key role in regulating the inflammatory and alloimmune responses following heart transplantation. Therapies that inhibit IL-6 signaling have emerged as promising strategies to prevent allograft rejection. Here, we review experimental and pre-clinical evidence that supports the potential use of IL-6 signaling blockade to improve outcomes in heart transplant recipients.

Addition of interleukin-6 receptor blockade to carfilzomib-based desensitization in a highly sensitized nonhuman primate model

Sensitized patients, those who had prior exposure to foreign human leukocyte antigens, are transplanted at lower rates due to challenges in finding suitable organs. Desensitization strategies have permitted highly sensitized patients to undergo kidney transplantation, albeit with higher rates of rejection. This study assesses targeting plasma cell and interleukin (IL)-6 receptor for desensitization in a sensitized nonhuman primate kidney transplantation model. All animals were sensitized using two sequential skin transplants from maximally major histocompatibility complex-mismatched donors. Carfilzomib (CFZ)/tocilizumab (TCZ) desensitization (N = 6) successfully decreased donor-specific antibody (DSA) titers and prevented the expansion of B cells compared to CFZ monotherapy (N = 3). Dual desensitization further delayed, but did not prevent humoral rebound, as evidenced by a delayed increase in post-kidney transplant DSA titers. Accordingly, CFZ/TCZ desensitization conferred a significant survival advantage over CFZ monotherapy. A trend toward increased T follicular helper cells was also observed in the dual therapy group along the same timeline as an increase in DSA and subsequent graft loss. Cytomegalovirus reactivation also occurred in the CFZ/TCZ group but was prevented with ganciclovir prophylaxis. In accordance with prior studies of CFZ-based dual desensitization strategies, the addition of IL-6 receptor blockade resulted in desensitization with further suppression of posttransplant humoral response compared to CFZ monotherapy.

[Improving access to kidney transplantation for highly sensitized patients: What place for IL-6 pathway blockade in desensitization protocols?]

BACKGROUND

Desensitization allows kidney transplantation for HLA highly sensitized subjects. Due to the central role of IL-6 in immunological response, tocilizumab (monoclonal antibody directed against IL-6 receptor) could probably improve desensitization efficacy.

METHODS

Pubmed systematic review by using MeSH terms: tocilizumab, clazakizumab, interleukin-6 blockade, kidney transplantation, kidney graft and desensitization.

STUDIES

IL-6 plays a role in humoral response (plasmocyte differentiation induced by lymphocyte T, IL-21 secretion) as well as in cellular response (differentiation of LT Th17 rather than T reg). In desensitization field, tocilizumab was first studied as second-line treatment after failing of standard-of-care (apheresis, rituximab ± IgIV). Recent study showed that tocilizumab as a monotherapy attenuated anti-HLA antibodies rates but was not sufficient to allow transplantation. However, lymphocyte immunophenotyping showed that tocilizumab hindered B cells maturation. Thereby, tocilizumab could improve long-term efficacy of desensitization, by limiting the anti-HLA rebound and so avoiding antibody-mediated rejection. This hypothesis is supported by a recent study which used clazakizumab (monoclonal antibody directed against IL-6) in association with standard-of-care. In that study, clazakizumab was continued after kidney transplantation. Results were encouraging because 9/10 patients were transplanted and there was no donor-specific antibody at 6 months post-transplantation.

CONCLUSION

IL-6 pathway blockade as a monotherapy fails to desensitize HLA highly sensitized kidney transplant candidates. In association with standard-of-care, it does not seem to significatively improve kidney allograft access (short-term efficacy) vs. standard-of-care only. However, it could improve long-term prognosis of HLA incompatible transplantation by orienting the response towards a tolerogenic profile, by hindering B-cell maturation and, thereby, avoiding DSA rebounds after transplantation. This hypothesis needs to be proven by further studies.

Tocilizumab in the treatment of active chronic humoral rejection resistant to standard therapy

INTRODUCTION

There is no consensus on the most appropriate treatment for chronic active antibody-mediated rejection (cAMR). Recent studies suggest that treatment with tocilizumab (TCZ) may stabilize graft function, decrease the intensity of donor-specific HLA antibodies (DSAs) and reduce inflammation of microcirculation.

PATIENTS AND METHODS

Observational study with renal allograft recipients diagnosed with cAMR (n = 5) who had not submitted a response to traditional treatment based on the combination of plasma replacements, immunoglobulins, and rituximab. Patients were told to be treated with TCZ as compassionate use in six doses per month (8 mg/kg/month). Renal function, proteinuria, and the intensity of DSAs were monitored during follow-up.

RESULTS

Five patients, average age 60 ± 13 years, three male and two retrasplants (cPRA average 55%) with preformed DSAs. Treatment with TCZ was initiated within 47 ± 52 days of biopsy. In two cases treatment was discontinued after the first dose, by severe bicitopenia with cytomegalovirus viremia and by graft failure, respectively. In the three patients who completed treatment, no stability of renal function (serum creatinine from 1.73 ± 0.70 to 2.04 ± 0.52 mg/dL, e-FGR 4 6 ± 15 to 36 ± 16 mL/min), showed increased proteinuria (3.2 ± 4.0 to 6.9 ± 11.0 g/g) and the intensity of DSAs maintain stable. No changes were observed in the degree of inflammation of microcirculation (g+pt 4.2 ± 0.8 vs. 4.3 ± 1.0) or in the degree of transplant glomerulopathy (cg 1.2 ± 0.4 vs. 1.8 ± 1.0).

CONCLUSIONS

TCZ therapy does not appear to be effective in modifying the natural history of chronic active antibody-mediated rejection, does not improve the degree of inflammation of microcirculation and does not reduces the intensity of DSAs.

Novel approaches for long-term lung transplant survival

Allograft failure remains a major barrier in the field of lung transplantation and results primarily from acute and chronic rejection. To date, standard-of-care immunosuppressive regimens have proven unsuccessful in achieving acceptable long-term graft and patient survival. Recent insights into the unique immunologic properties of lung allografts provide an opportunity to develop more effective immunosuppressive strategies. Here we describe advances in our understanding of the mechanisms driving lung allograft rejection and highlight recent progress in the development of novel, lung-specific strategies aimed at promoting long-term allograft survival, including tolerance.

Emerging drugs for antibody-mediated rejection after kidney transplantation: a focus on phase II & III trials

INTRODUCTION

Antibody-mediated rejection (ABMR) is a leading cause of kidney allograft failure. Its therapy continues to be challenge, and no treatment has been approved for the market thus far.

AREAS COVERED

In this article, we discuss the pathophysiology and phenotypic presentation of ABMR, the current level of evidence to support the use of available therapeutic strategies, and the emergence of tailored drugs now being evaluated in systematic clinical trials. We searched PubMed, Clinicaltrials.gov and Citeline's Pharmaprojects for pertinent information on emerging anti-rejection strategies, laying a focus on phase II and III trials.

EXPERT OPINION

Currently, we rely on the use of apheresis for alloantibody depletion and intravenous immunoglobulin (referred to as standard of care), preferentially in early active ABMR. Recent systematic trials have questioned the benefits of using the CD20 antibody rituximab or the proteasome inhibitor bortezomib. However, there are now several promising treatment approaches in the pipeline, which are being trialed in phase II and III studies. These include interleukin-6 antagonism, CD38-targeting antibodies, and selective inhibitors of complement. On the basis of the information that has emerged so far, it seems that innovative treatment strategies for clinical use in ABMR may be available within the next 5-10 years.

Tocilizumab and Active Antibody-Mediated Rejection in Kidney Transplantation: A Literature Review

Introduction

Chronic kidney disease (CKD) is a major public-health problem that increases the risk of end-stage kidney disease (ESKD), cardiovascular diseases, and other complications. Kidney transplantation is a renal-replacement therapy that offers better survival compared to dialysis. Antibody-mediated rejection (ABMR) is a significant complication following kidney transplantation: it contributes to both short- and long-term injury. The standard-of-care (SOC) therapy combines plasmapheresis and Intravenous Immunoglobulins (IVIg) with or without steroids, with or without rituximab: however, despite this combined treatment, ABMR remains the main cause of graft loss. IL-6 is a key cytokine: it regulates inflammation, and the development, maturation, and activation of T cells, B cells, and plasma cells. Tocilizumab (TCZ) is the main humanized monoclonal aimed at IL-6R and appears to be a safe and possible strategy to manage ABMR in sensitized recipients. We conducted a literature review to assess the place of the anti-IL-6R monoclonal antibody TCZ within ABMR protocols.

Materials and Methods

We systematically reviewed the PubMed literature and reviewed six studies that included 117 patients and collected data on the utilization of TCZ to treat ABMR.

Results

Most studies report a significant reduction in levels of Donor Specific Antibodies (DSAs) and reduced inflammation and microvascular lesions (as found in biopsies). Stabilization of the renal function was observed. Adverse events were light to moderate, and mortality was not linked with TCZ treatment. The main side effect noted was infection, but infections did not occur more frequently in patients receiving TCZ as compared to those receiving SOC therapy.

Conclusion

TCZ may be an alternative to SOC for ABMR kidney-transplant patients, either as a first-line treatment or after failure of SOC. Further randomized and controlled studies are needed to support these results.

Clazakizumab for desensitization in highly sensitized patients awaiting transplantation

Alloantibodies are a significant barrier to successful transplantation. While desensitization has emerged, efficacy is limited. Interleukin-6 (IL-6) is an important mediator of inflammation and immune cell activation. Persistent IL-6 production increases the risk for alloantibody production. Here we report our experience with clazakizumab (anti-IL-6) for desensitization of highly HLA-sensitized patients (HS). From March 2018 to September 2020, 20 HS patients were enrolled in an open label pilot study to assess safety and limited efficacy of clazakizumab desensitization. Patients received PLEX, IVIg, and clazakizumab 25 mg monthly X6. If transplanted, graft function, pathology, HLA antibodies and regulatory immune cells were monitored. Transplanted patients received standard immunosuppression and clazakizumab 25 mg monthly posttransplant. Clazakizumab was well tolerated and associated with significant reductions in class I and class II antibodies allowing 18 of 20 patients to receive transplants with no DSA rebound in most. Significant increases in T_reg and B_reg cells were seen posttransplant. Antibody-mediated rejection occurred in three patients. The mean estimated glomerular filtration rate at 12 months was 58 ± 29 ml/min/1.73 m² . Clazakizumab was generally safe and associated with significant reductions in HLA alloantibodies and high transplant rates for highly-sensitized patients. However, confirmation of efficacy for desensitization requires assessment in randomized controlled trials.

Novel Soluble Mediators of Innate Immune System Activation in Solid Allograft Rejection

During the past years, solid allograft rejection has been considered the consequence of either cellular- or antibody-mediated reaction both being part of the adaptive immune response, whereas the role of innate immunity has been mostly considered less relevant. Recently, a large body of evidence suggested that the innate immune response and its soluble mediators may play a more important role during solid allograft rejection than originally thought. This review will highlight the role of novel soluble mediators that are involved in the activation of innate immunity during alloimmune response and solid allograft rejection. We will also discuss emerging strategies to alleviate the aforementioned events. Hence, novel, feasible, and safe clinical therapies are needed to prevent allograft loss in solid organ transplantation. Fully understanding the role of soluble mediators of innate immune system activation may help to mitigate solid allograft rejection and improve transplanted recipients' outcomes.

Immunosuppression and SARS-CoV-2 Infection in Kidney Transplant Recipients

Kidney transplant recipients (KTRs) infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may have an increased risk of mortality compared with the general population and hemodialysis patients. As these patients are immunosuppressed, it might seem obvious to attribute this excess mortality to the impaired immunity induced by immunosuppression. In line with this reasoning is the low immune response, both cellular and humoral, that KTRs mount in response to the anti–SARS-CoV-2 vaccine; however, acute respiratory distress syndrome associated with coronavirus disease 2019 is triggered by a state of inflammation and cytokine release syndrome that lead to pulmonary damage and increased mortality. In that context, immunosuppressive treatment dampening the immune response could, in theory, be potentially beneficial.

This review aims at analyzing the current knowledge on the impact of immunosuppressive treatment on mortality in SARS-CoV-2–infected KTRs, the optimal management of immunosuppression in the coronavirus disease 2019 era, and the vaccine response and management in immunosuppressed KTRs.

Evaluation of Clazakizumab (anti-IL-6) in Patients with Treatment-Resistant Chronic Active Antibody Mediated Rejection of Kidney Allografts

Introduction

Interleukin-6 (IL-6) is an important mediator of inflammation and activation of T cells, B cells, and plasma cells. Excessive IL-6 production is linked to human diseases characterized by unregulated antibody production, including alloimmunity, where persistence of donor-specific antibodies (DSAs), chronic active antibody-mediated rejection (cAMR), and graft loss are noted. Here, we report our experience investigating clazakizumab, a novel IL-6 inhibitor, in treating human leukocyte antigen (HLA)-sensitized patients with cAMR.

Methods

Between February 2018 and January 2019, 10 adults with biopsy-proven cAMR were enrolled in a phase 2, single-center, open-label study. Patients received clazakizumab 25 mg subcutaneously (s.c.) monthly for 12 months, with a 6-month protocol biopsy. Primary end points included patient survival, graft survival, estimated glomerular filtration rate (eGFR), and safety. Secondary end points assessed immune markers (DSAs, IgG, T-regulatory [Treg] cells). At 12 months, stable patients entered a long-term extension (LTE).

Results

LTE patients received clazakizumab for >2.5 years. Mean eGFRs showed significant declines from −24 months to study initiation (0 months) (52.8 ± 14.6 to 38.11 ± 12.23 ml/min per 1.73 m², P = 0.03). However, after initiation of clazakizumab, eGFR stabilized at (41.6 ± 14.2 and 38.1 ± 20.3 ml/min per 1.73 m², at 12 and 24 months, respectively). Banff 2017 analysis of pre- and post-treatment biopsies showed reductions in g+ptc and C4d scores. DSA reductions were seen in most patients. Adverse events (AEs) were minimal, and 2 graft losses occurred, both in patients who discontinued clazakizumab therapy at 6 months and 12 months after study initiation.

Conclusion

In this small cohort of patients with cAMR, clazakizumab treatment showed a trend toward stabilization of eGFR and reductions in DSA and graft inflammation. No significant safety issues were observed. A randomized, placebo-controlled clinical trial (IMAGINE) of clazakizumab in cAMR treatment is underway (NCT03744910).

Kidneys in SARS-CoV-2 Era; a challenge of multiple faces

INTRODUCTION

With the evolution of SARS-CoV-2 pandemic, it was believed to be a direct respiratory virus. But, its deleterious effects were observed on different body systems, including kidneys.

AIM OF WORK

In this review, we tried as much as we can to summarize what has been discussed in the literature about the relation between SARS-CoV-2 infection and kidneys since December, 2019.

METHODS

Each part of the review was assigned to one or two authors to search for relevant articles in three databases (Pubmed, Scopus and Google scholar) and collected data were summarized and revised by two independent researchers.

CONCLUSION

The complexity of COVID-19 pandemic and kidney could be attributed to the direct effect of SARS-CoV-2 infection on the kidneys, different clinical presentation, difficulties confronting dialysis patients, restrictions of the organ transplant programs, poor outcomes and bad prognosis in patients with known history of kidney diseases who got infected with SARS-CoV-2. This article is protected by copyright. All rights reserved.

Anti-Interleukin 6 Therapeutics for Chronic Antibody-Mediated Rejection In Kidney Transplant Recipients

Chronic antibody-mediated rejection is the predominant cause for late renal allograft loss for which there is, as yet, no treatment approved by the US Food and Drug Administration, although there are clinical trials in progress to evaluate novel treatment strategies. The current standard of care treatment is based on expert consensus, rather than scientific evidence, and includes glucocorticoids, plasma exchange, and intravenous immunoglobulin, with or without rituximab or bortezomib. The low success rate with presently established management protocols represents a conspicuous exigency in the field of kidney transplantation. This review focuses on the biologic basis for interleukin 6 inhibitors, specifically tocilizumab and clazakizumab, and the safety and efficacy profiles of these agents for treatment of chronic antibodymediated rejection in kidney transplant recipients.

Tocilizumab and Desensitization in Kidney Transplant Candidates: Personal Experience and Literature Review

Desensitization (DES) allows kidney transplantation for highly HLA-sensitized subjects. Due to the central role of IL-6 in the immunological response, tocilizumab may improve DES efficacy. Thus, we conducted a PubMed systematic review using the MeSH terms tocilizumab, interleukin-6, kidney transplantation, and desensitization. Tocilizumab (TCZ) was first studied for DES as the second-line treatment after failure of a standard DES protocol (SP) (apheresis, rituximab +/- IVIg). Although TCZ (as a monotherapy) attenuated anti-HLA antibody rates, it did not permit transplantation. However, lymphocyte immuno-phenotyping has shown that TCZ hinders B-cell maturation and thus could improve the long-term efficacy of DES by limiting anti-HLA rebound and so avoid antibody-mediated rejection. This hypothesis is supported by a recent study where clazakizumab, a monoclonal antibody directed against IL-6, was continued after kidney transplantation in association with an SP. Nine out of ten patients were then eligible for transplantation, and there were no donor-specific antibodies at 6 months post-transplantation. In association with an SP, tocilizumab does not seem to significantly improve kidney-allograft access (short-term efficacy) vs. a SP only. However, it could improve the long-term prognosis of HLA-incompatible transplantation by hindering B-cell maturation and, thereby, avoiding donor-specific antibody rebounds post-transplantation.

Donor genetic variants in interleukin-6 and interleukin-6 receptor associate with biopsy-proven rejection following kidney transplantation

Rejection after kidney transplantation remains an important cause of allograft failure that markedly impacts morbidity. Cytokines are a major player in rejection, and we, therefore, explored the impact of interleukin-6 (IL6) and IL-6 receptor (IL6R) gene polymorphisms on the occurrence of rejection after renal transplantation. We performed an observational cohort study analyzing both donor and recipient DNA in 1271 renal transplant‐pairs from the University Medical Center Groningen in The Netherlands and associated single nucleotide polymorphisms (SNPs) with biopsy-proven rejection after kidney transplantation. The C-allele of the IL6R SNP (Asp358Ala; rs2228145 A > C, formerly rs8192284) in donor kidneys conferred a reduced risk of rejection following renal transplantation (HR 0.78 per C-allele; 95%-CI 0.67–0.90; P = 0.001). On the other hand, the C-allele of the IL6 SNP (at position-174 in the promoter; rs1800795 G > C) in donor kidneys was associated with an increased risk of rejection for male organ donors (HR per C-allele 1.31; 95%-CI 1.08–1.58; P = 0.0006), but not female organ donors (P = 0.33). In contrast, neither the IL6 nor IL6R SNP in the recipient showed an association with renal transplant rejection. In conclusion, donor IL6 and IL6R genotypes but not recipient genotypes represent an independent prognostic marker for biopsy-proven renal allograft rejection.

Safety of tocilizumab in COVID-19 pregnant women and their newborn: A retrospective study

WHAT IS KNOWN AND OBJECTIVE

Tocilizumab is an IL-6 receptor inhibitor agent which has been proposed as a candidate to stop the inflammatory phase of infection by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, safety data of tocilizumab in pregnant women and their newborn are scarce. We aimed to describe maternal and neonatal safety outcomes associated with tocilizumab treatment in pregnant women with severe COVID-19.

METHODS

This is a retrospective study of severe COVID-19 pregnant women, treated with tocilizumab in two Spanish hospitals between 1 March and 31 April 2020. Demographics, medical history, clinical and radiologic findings, treatment information and laboratory data of mothers and their newborns were collected from electronic medical records.

RESULTS AND DISCUSSION

A total of 12 pregnant women were identified to have received tocilizumab during pregnancy in the two hospitals. Median gestational age at admission was 27.7 weeks (interquartile range, 18.0-36.4). Most of them received lopinavir/ritonavir, azithromycin and hydroxychloroquine, two patients received corticosteroids and one received interferon beta 1B. All 12 pregnancies resulted in live births. Somatometric values were normal for all newborns, and evolution at 14 and 28 days was favourable for all of them. Hepatotoxicity was observed in 2 patients, which improved or resolved at discharge. Cytomegalovirus reactivation was detected in another patient who had also received corticosteroids for 15 days, causing a congenital infection in her newborn. Both hepatotoxicity and viral reactivation adverse events were classified as possibly related to tocilizumab administration according to Naranjo's causality algorithm.

WHAT IS NEW AND CONCLUSIONS

It does not appear that tocilizumab has detrimental effects for the mother and newborn. Close monitoring of infections should be considered, especially if other immunosuppressive agents are used.

IL-6 Directed Therapy in Transplantation

Purpose of Review

IL-6 is a pleiotropic, pro-inflammatory cytokine that plays an integral role in the development of acute and chronic rejection after solid organ transplantation. This article reviews the experimental evidence and current clinical application of IL-6/IL-6 receptor (IL-6R) signaling inhibition for the prevention and treatment of allograft injury.

Recent Findings

There exists a robust body of evidence linking IL-6 to allograft injury mediated by acute inflammation, adaptive cellular/humoral responses, innate immunity, and fibrosis. IL-6 promotes the acute phase reaction, induces B cell maturation/antibody formation, directs cytotoxic T-cell differentiation, and inhibits regulatory T-cell development. Importantly, blockade of the IL-6/IL-6R signaling pathway has been shown to mitigate its harmful effects in experimental studies, particularly in models of kidney and heart transplant rejection. Currently, available agents for IL-6 signaling inhibition include monoclonal antibodies against IL-6 or IL-6R and janus kinase inhibitors. Recent clinical trials have investigated the use of tocilizumab, an anti-IL-6R mAb, for desensitization and treatment of antibody-mediated rejection (AMR) in kidney transplant recipients, with promising initial results. Further studies are underway investigating the use of alternative agents including clazakizumab, an anti-IL-6 mAb, and application of IL-6 signaling blockade to clinical cardiac transplantation.

Summary

IL-6/IL-6R signaling inhibition provides a novel therapeutic option for the prevention and treatment of allograft injury. To date, evidence from clinical trials supports the use of IL-6 blockade for desensitization and treatment of AMR in kidney transplant recipients. Ongoing and future clinical trials will further elucidate the role of IL-6 signaling inhibition in other types of solid organ transplantation.

Chronic Active Antibody-Mediated Rejection Following COVID-19 Infection in a Kidney Transplant Recipient: A Case Report

Kidney transplant recipients who develop coronavirus disease 2019 (COVID-19) are at increased risk of life-threatening illness, which often requires reducing immunosuppression despite the potential risk of causing an allograft rejection. Herein, we describe the clinical presentation and course of a kidney transplant recipient who acquired COVID-19 and was hospitalized with severe symptoms and hypoxemia. Upon admission, the patient was found to have elevated de novo donor-specific antibodies (DSA) yielding a positive cytotoxicity crossmatch and concurrent elevated plasma donor-derived cell-free DNA (dd-cfDNA) level, indicating a possible ongoing rejection despite improvement in his serum creatinine. Because of persistent positive COVID-19 tests and stable serum creatinine, a kidney allograft biopsy was initially deferred and his dd-cfDNA and DSA were monitored closely postdischarge. Three months later, because of persistent elevated dd-cfDNA and positive DSA, a kidney allograft biopsy was performed, which showed chronic active antibody-mediated rejection. Accordingly, the patient was treated with intravenous immunoglobulin and his maintenance immunosuppressive regimen was increased.

Interleukin 6 Receptor Blockade to Treat Chronic Active Antibody-Mediated Rejection in Kidney Transplant: A Case Report With Review of Relevant Literature

A 40-year-old male patient with a pretransplant calculated panel reactive antibody of 0 and no prior sensitizing events developed mixed active antibody-mediated rejection and acute cellular rejection (Banff grade 1A) 1.5 years posttransplant. Testing for donor-specific antibody or non-human leukocyte antigen antibody (major histocompatibility complex class I chain-related antigen A/angiotensin II type I receptor) was negative. Biopsy demonstrated diffuse C4d staining in peritubular capillaries. The patient was treated with standard of care, including plasma-pheresis and intravenous immunoglobulin along with steroids, with return of renal function to baseline. However, 1 year after treatment, he developed chronic active antibody-mediated rejection without any donor-specific antibodies. We believe he did have smoldering antibody-mediated rejection that had progressed to a more chronic state over time. He was then treated with tocilizumab and had a successful return of serum creatinine to baseline. One year after treatment, he still has stable renal function, suggesting a role of tocilizumab in stabilizing renal function in patients with chronic active antibody-mediated rejection for which there is no Food and Drug Administration-approved treatment.

Novel strategies to target the humoral alloimmune response

Antibody-mediated rejection (ABMR) represents a major cause of late allograft loss in solid organ transplantation worldwide. This process is driven by donor-specific antibodies (DSA), which develop either de-novo or, in sensitized patients, are preformed at the time of transplantation. Effective targeting of ABMR has been hampered by a lack of robust randomized controlled trials (RCT), required for the regulatory approval of new therapeutics. In this review, we discuss the evidence behind the present "standard" of care and recent progress in the development of novel strategies targeting different aspects of the alloimmune humoral response, including naïve and memory B-cell activation, the germinal centre reaction, plasma cell survival and antibody effector functions. In particular, we focus on co-stimulation blockade and its combination with next-generation proteasome inhibitors, new depleting monoclonal antibodies (anti-CD19, anti-BCMA, anti-CD38, anti-CD138), interleukin-6 blockade, complement inhibition and DSA degradation. These treatment modalities, when used in the appropriate clinical context and combination, have the potential to finally improve long-term allograft survival.

Immunomodulatory Therapies for COVID-19 in Solid Organ Transplant Recipients

PURPOSE OF REVIEW

Severe coronavirus disease 2019 (COVID-19) is characterized by the development of a deleterious hyperinflammatory response, in which the pleiotropic cytokine interleukin (IL)-6 plays a pivotal role. The administration of immunomodulatory therapies has been proposed to revert the tissue damage induced by COVID-19-related cytokine release syndrome (CRS). The present review summarizes the biological rationale and available clinical experience with this therapeutic strategy in the specific scenario solid organ transplantation (SOT).

RECENT FINDINGS

A number of case reports, case series, and non-controlled cohort studies have assessed the efficacy and safety of the anti-IL-6-receptor monoclonal tocilizumab in SOT (namely kidney transplantation) recipients with COVID-19 pneumonia and CRS. Although the heterogeneity in patient management and the lack of a control group limit the interpretation of these results, tocilizumab therapy appears to provide some clinical benefit in post-transplant COVID-19 and to be reasonably safe in terms of bacterial superinfection. A large randomized clinical trial (RCT) has shown survival benefit with adjuvant corticosteroids in non-transplant patients, but supporting evidence is scarce for SOT recipients and confounded by the variable adjustment of baseline immunosuppression. Anecdotal experiences have been reported with the use of the anti-IL-1 agent anakinra and the NLRP3 inflammasome inhibitor colchicine in this population.

SUMMARY

Immunomodulation has emerged as a promising option for SOT recipients with COVID-19-related CRS, with available experience mainly restricted to the anti-IL-6 agent tocilizumab. However, the supporting evidence is scarce and of low quality. In the absence of RCT, observational studies including well-matched control groups should be designed in future.

The role of novel therapeutic approaches for prevention of allosensitization and antibody-mediated rejection

Modification of pathogenic antibodies and their effector functions in autoimmune diseases or use of B cell/plasma cell-directed anticancer therapies have illuminated the biologic relevance of B cells, plasma cells (PCs), and pathogenic antibodies and complement in alloimmunity. They have also rejuvenated interest in how B cells mediate multiple effector functions that include antibody production, antigen presentation to T cells, costimulation, and the production of immune stimulating and immune modulatory cytokines that drive dysfunctional immune responses. Current methods to reduce alloantibodies are only modestly successful. Rituximab is used for desensitization and antibody-mediated rejection (AMR) treatment by targeting CD20 found on B-lymphocytes. However, PCs do not express CD20, likely explaining the limited success of this approach. Intravenous immunoglobulin and plasmapheresis (PLEX) have limited success due to antibody rebound. Despite attempts to develop tolerable therapeutics for management of AMR, none, to date, have been universally accepted or obtained Food and Drug Administration approval. Lack of approved therapeutics often results in patients having a much shorter graft survival due to AMR. Repurposing drugs from autoimmunity and cancer immunotherapy has rapidly yielded important advancements in the care of AMR patients. Here we discuss emerging therapeutics aimed at prevention and treatment of AMR.

Recent Advances and Clinical Outcomes of Kidney Transplantation

Recent advances in surgical, immunosuppressive and monitoring protocols have led to the significant improvement of overall one-year kidney allograft outcomes. Nonetheless, there has not been a significant change in long-term kidney allograft outcomes. In fact, chronic and acute antibody-mediated rejection (ABMR) and non-immunological complications following kidney transplantation, including multiple incidences of primary kidney disease, as well as complications such as cardiovascular diseases, infections, and malignancy are the major factors that have contributed to the failure of kidney allografts. The use of molecular techniques to enhance histological diagnostics and noninvasive surveillance are what the latest studies in the field of clinical kidney transplant seem to mainly focus upon. Increasingly innovative approaches are being used to discover immunosuppressive methods to overcome critical sensitization, prevent the development of anti-human leukocyte antigen (HLA) antibodies, treat chronic active ABMR, and reduce non-immunological complications following kidney transplantation, such as the recurrence of primary kidney disease and other complications, such as cardiovascular diseases, infections, and malignancy. In the present era of utilizing electronic health records (EHRs), it is strongly believed that big data and artificial intelligence will reshape the research done on kidney transplantation in the near future. In addition, the utilization of telemedicine is increasing, providing benefits such as reaching out to kidney transplant patients in remote areas and helping to make scarce healthcare resources more accessible for kidney transplantation. In this article, we discuss the recent research developments in kidney transplants that may affect long-term allografts, as well as the survival of the patient. The latest developments in living kidney donation are also explored.