Successful Therapy With Rituximab of Refractory Acute Humoral Renal Transplant Rejection: A Case Report

Refractory CD20 Positive Cellular Rejection in Living Kidney Transplant: A Case Report and Review of Literature

Transplant is the optimal therapy for patients with end-stage renal disease. Acute cellular rejection refractory to treatment remains a major risk factor for graft loss and poor outcomes. In this study, we describe a 39-year-old man who received a living-related kidney transplant. Two days after transplant, the patient displayed acute deterioration of graft function. Conventional anti-rejection therapy was initiated, but graft function did not improve. Biopsy revealed acute cellular rejection (grade IIA), and C4d and HLA antibodies were negative. Immunohistochemistry phenotyping revealed clusters of CD20-positive lymphocytes, with 80% being CD3 positive. Rituximab was prescribed, and graft function improved dramatically. After 1 week, a second graft biopsy was done due to lagging of graft function, shown by serum creatinine of 2.1 mg/dL. Biopsy revealed regenerating acute tubular necrosis with disappearance of the CD20-positive lymphocyte cluster infiltrates. Two year, after transplant, the patient's graft function maintained stable. Phenotyping of the cellular infiltrate is important as it may lead to a proper selection of immunosuppression and consequent improvement of graft outcome.

One-year Results of the Effects of Rituximab on Acute Antibody-Mediated Rejection in Renal Transplantation: RITUX ERAH, a Multicenter Double-blind Randomized Placebo-controlled Trial

BACKGROUND

Treatment of acute antibody-mediated rejection (AMR) is based on a combination of plasma exchange (PE), IVIg, corticosteroids (CS), and rituximab, but the place of rituximab is not clearly specified in the absence of randomized trials.

METHODS

In this phase III, multicenter, double-blind, placebo-controlled trial, we randomly assigned patients with biopsy-proven AMR to receive rituximab (375 mg/m) or placebo at day 5. All patients received PE, IVIg, and CS. The primary endpoint was a composite of graft loss or no improvement in renal function at day 12.

RESULTS

Among the 38 patients included, at 1 year, no deaths occurred, but 1 graft loss occurred in each group. The primary endpoint frequency was 52.6% (10/19) and 57.9% (11/19) in the rituximab and placebo groups, respectively (P = 0.744). Renal function improved in both groups, as soon as day 12 with no difference in serum creatinine level and proteinuria at 1, 3, 6, and 12 months. Supplementary administration of rituximab and total number of IVIg and PE treatments did not differ between the 2 groups. Both groups showed improved histological features of AMR and Banff scores at 1 and 6 months, with no significant difference between groups but with a trend in favor of the rituximab group. Both groups showed decreased mean fluorescence intensity of donor-specific antibodies as soon as day 12, with no significant difference between them but with a trend in favor of the rituximab group at 12 months.

CONCLUSIONS

After 1 year of follow-up, we observed no additional effect of rituximab in patients receiving PE, IVIg, and CS for AMR. Nevertheless, our study was underpowered and important differences between groups may have been missed. Complementary trials with long-term follow-up are needed.

Rituximab in renal transplantation

Rituximab is a chimeric anti-CD20 monoclonal antibody that leads to B cell depletion. It is not licensed for use in renal transplantation but is in widespread use in ABO blood group incompatible transplantation. It is an effective treatment for post-transplant lymphoproliferative disorder, and is also used in both HLA antibody incompatible renal transplantation and the treatment of acute rejection. Recent evidence suggests rituximab may prevent the development of chronic antibody mediated rejection. The mechanisms underlying its effects are likely to relate both to long-term effects on plasma cell development and to the impact on B cell modulation of T cell responses. Rituximab (in multiple doses or in combination with other monoclonal antibodies and/or other immunosuppressants) may lead to an increase in infectious complications, although the evidence is not clear. Rarely, the drug can cause a cytokine release syndrome, thrombocytopenia and neutropenia. It has been related to an increased risk of progressive multifocal leucoencephalopathy and, recently, deaths from cardiovascular causes. Trials examining the effects of rituximab in induction therapy for compatible renal transplantation and the treatment of chronic antibody mediated rejection are ongoing. These trials should aid greater understanding of the role of B-cells in the alloresponse to renal transplantation.

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.

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).

The immunologic constant of rejection

The complexity underlying a pathologic process does not necessarily require a complex explanation. The biology determining allograft or cancer rejection, autoimmunity or tissue damage during pathogen infections is complex; however, common patterns are emerging that lead to a common final outcome. For instance, tissue destruction occurs with resolution of the pathogenic process (cancer, infection) or tissue damage and organ failure (autoimmunity, allograft rejection). Observations in humans based on transcriptional profiling converge into what we call an 'immunologic constant of rejection' that characterizes such occurrences. This constant includes the coordinate activation of interferon-stimulated genes (ISGs) and immune effector functions (IEFs). Understanding this final effector pathway may suggest novel strategies for the induction or inhibition of tissue-specific destruction with therapeutic intent in cancer and other immune pathologies.