Rabbit anti-human thymocyte immunoglobulin for the rescue treatment of chronic antibody-mediated rejection after pediatric kidney transplantation

Antibody-mediated rejection after kidney transplantation in children; therapy challenges and future potential treatments

Antibody‐mediated rejection (AMR) remains one of the most critical problems in renal transplantation, with a significant impact on patient and graft survival. In the United States, no treatment has received FDA approval jet. Studies about treatments of AMR remain controversial, limited by the absence of a gold standard and the difficulty in creating large, multi‐center studies. These limitations emerge even more in pediatric transplantation because of the limited number of pediatric studies and the occasional use of some therapies with unknown and poorly documented side effects. The lack of recommendations and the unsharp definition of different forms of AMR contribute to the challenging management of the therapy by pediatric nephrologists. In an attempt to help clinicians involved in the care of renal transplanted children affected by an AMR, we rely on the latest recommendations of the Transplantation Society (TTS) for the classification and treatment of AMR to describe treatments available today and potential new treatments with a particular focus on the pediatric population.

Differential Treatment Effects for Renal Transplant Recipients With DSA-Positive or DSA-Negative Antibody-Mediated Rejection

Background

Antibody-mediated rejection (ABMR) is the main cause of renal allograft loss. The most common treatment strategy is based on plasmapheresis plus the subsequent administration of intravenous immunoglobulin (IVIG). Unfortunately, no approved long-term therapy is available for ABMR. The current study was designed to analyze the effect of various ABMR treatment approaches on allograft survival and to compare treatment effects in the presence or absence of donor-specific antibodies (DSAs).

Methods

This single-center study retrospectively analyzed 102 renal allograft recipients who had biopsy-proven ABMR after transplant. DSA was detectable in 61 of the 102 patients. Initial standard treatment of ABMR consisted of plasmapheresis (PS) or immunoadsorption (IA), followed by a single course of IVIG. In case of nonresponse or recurrence, additional immunosuppressive medications, such as rituximab, bortezomib, thymoglobulin, or eculizumab, were administered. In a second step, persistent ABMR was treated with increased maintenance immunosuppression, long-term therapy with IVIG (more than 1 year), or both.

Results

Overall graft survival among transplant patients with ABMR was <50% after 3 years of follow-up. Compared to the use of PS/IA and IVIG alone, the use of additional immunosuppressive medications had no beneficial effect on allograft survival (p = 0.83). Remarkably, allografts survival rates were comparable between patients treated with the combination of PS/IA and IVIG and those treated with a single administration of IVIG (p = 0.18). Renal transplant patients with ABMR but without DSAs benefited more from increased maintenance immunosuppression than did DSA-positive patients with ABMR (p = 0.01). Recipients with DSA-positive ABMR exhibited significantly better allograft survival after long-term application of IVIG for more than 1 year than did recipients with DSA-negative ABMR (p = 0.02).

Conclusions

The results of our single-center cohort study involving kidney transplant recipients with ABMR suggest that long-term application of IVIG is more favorable for DSA-positive recipients, whereas intensification of maintenance immunosuppression is more effective for recipients with DSA-negative ABMR.

Clinical effect of rabbit anti-thymocyte globulin for chronic active antibody-mediated rejection after kidney transplantation

Chronic active antibody-mediated rejection (CAAMR) is a frequent cause of late graft loss. However, effective treatment for CAAMR after kidney transplantation has not yet been established. Here, we present the case of a kidney transplant recipient who recovered from CAAMR after administration of rabbit anti-thymocyte globulin. A 61-year-old man underwent ABO-compatible living-donor kidney transplantation for end-stage kidney disease; the kidney was donated by his wife. Five years after the transplant, the patient's serum creatinine level and urine protein-to-creatinine ratio increased. He was subsequently diagnosed with CAAMR based on the kidney allograft biopsy and the presence of donor-specific human leukocyte antigen antibodies. Rabbit anti-thymocyte globulin treatment was administered following steroid pulse therapy. Subsequently, his serum creatinine levels and urine protein to creatinine ratio improved. There was also an improvement in the pathological findings seen on biopsy and the mean fluorescence intensity of donor-specific antibodies. In conclusion, this report describes the case of a kidney transplant recipient who developed CAAMR, treated using rabbit anti-thymocyte globulin. This strategy might be a viable treatment option for CAAMR after a kidney transplant.

Alemtuzumab as Second-Line Treatment for Late Antibody-Mediated Rejection of Transplanted Kidneys

Whether the anti-CD52 monoclonal antibody alemtuzumab can be an effective treatment option for late antibody-mediated rejection (ABMR) is not known. In a single-center pilot study, 12 patients with late ABMR were given 30 mg subcutaneous alemtuzumab.Median time from transplantation to biopsy was 22 months with 10 of 12 recipients fulfilling criteria for the histologic diagnosis chronic-active ABMR. The estimated glomerular filtration rate (eGFR) loss before diagnosis was 1.2 mL/min/mo with graft loss (eGFR <15 mL/min) expected to occur within 2 years in 11 of 12 cases. All recipients showed no or an inadequate response to initial treatment with steroids and intravenous immunoglobulin. eGFR at time of alemtuzumab administration was 35 mL/min/1.73 m² (IQR, 30-42) and stabilized or improved in 10 of 12 recipients within 12 months. Proteinuria was stable in the year after alemtuzumab. At 3-year follow-up, the death-censored graft survival was 68% (uncensored graft survival was 58%). Five cases of 10 cases that could be evaluated at 3-year follow-up had stable eGFR (on average 44 mL/min at 12 months and 42 mL/min at 36 months). Alemtuzumab was generally well tolerated and only 2 cases of opportunistic infections were noted. One case of symptomatic parvovirus B infection and 1 case of BK viral infection occurred, which both cleared at follow-up. In conclusion, alemtuzumab may be of value as a second-line treatment for late ABMR with rapid loss of eGFR.

Characterizing the frequency of modifiable histological changes observed on surveillance biopsies in pediatric kidney allograft recipients

BACKGROUND

Rejection is responsible for just under 50% of graft loss in the pediatric kidney transplant population. Early identification and treatment of allograft injury, specifically modifiable pathologies such as subclinical rejection (SCR), calcineurin inhibitor toxicity, and BK virus nephropathy, may improve allograft survival. Protocol surveillance biopsy (SB) currently offers the earliest opportunity for targeted interventions.

METHODS

This is a single-center retrospective review of 215 kidney SBs obtained from 2008 to 2016 in 97 pediatric kidney transplant recipients. SBs were obtained at 6, 12, and 24 months post-transplantation. Frequency of abnormal histologic findings, estimated glomerular filtration rate at time of SB, and SB-related complications were recorded. Data were analyzed to investigate possible time trends and the presence of demographic or clinical associations with abnormal histologic findings.

RESULTS

Potentially modifiable histologic findings were seen in 38.1% of all SBs. SCR was found with increasing frequency across all time points with an estimated 49% increase in the odds of a SCR finding per additional 6 months post-transplantation (aOR 1.49, 95% CI 1.06-2.09, p = 0.022). Among follow-up biopsies in patients who underwent treatment for SCR, 50% had no SCR and 18.8% showed histologic improvement. The complication rate associated with SB was 1.9% (4/215 SBs) and consisted of only minor complications.

CONCLUSIONS

SBs are safe and offer the opportunity to identify and treat modifiable histologic changes in the pediatric kidney transplant population. The performance of SBs for up to 2 years after transplantation can have meaningful clinical impact.

Effect of Rabbit Antithymocyte Globulin on Acute and Chronic Active Antibody-Mediated Rejection After Kidney Transplantation

BACKGROUND

Rabbit antithymocyte globulin (rATG) induction is associated with reduction in the occurrence of de novo donor-specific antibody (DSA) and antibody-mediated rejection (AMR). Therefore, rATG administration is considered as a treatment for AMR. However, only a few studies have investigated the treatment of AMR with rATG after kidney transplantation.

METHODS

Between April 2013 and March 2018, 162 consecutive de novo kidney transplantations were performed with induction immunosuppressive therapy comprising tacrolimus, mycophenolate mofetil, methylprednisolone, and basiliximab. AMR was diagnosed on the basis of the presence of DSA and episode biopsy findings. For DSA-positive recipients, plasmapheresis was performed to remove DSA before rATG administration (1.5 mg/kg for 5 days). Patients treated with rATG against active AMR were retrospectively analyzed for graft function.

RESULTS

A total of 13 kidney transplant recipients developed active AMR within 302 days after transplantation. After rATG administration, the mean serum creatinine and urine protein levels significantly declined from 3.03 mg/dL to 1.68 mg/dL (P = .002) within 46 days and from 3.01 g/gCr to 0.54 g/gCr (P = .006) within 106 days, respectively. The peripheral blood lymphocyte count rapidly decreased after rATG administration and remained low for 12 months. With regard to adverse events, fever (84.6%), cytomegaloviremia (84.6%), thrombocytopenia (61.5%), anemia (30.8%), and neutropenia (15.4%) occurred within 3 months after rATG administration.

CONCLUSIONS

rATG improved graft function by suppressing peripheral blood lymphocytes in kidney transplant recipients with active AMR. The rATG administration as a treatment for active AMR may contribute to positive graft outcomes after kidney transplantation.