Results of a multicenter prospective clinical study in Japan for evaluating efficacy and safety of desensitization protocol based on rituximab in ABO-incompatible kidney transplantation

Immunological risk and complement genetic evaluations in early onset de novo thrombotic microangiopathy after living donor kidney transplantation: A Japanese multicenter registry

BACKGROUND

Thrombotic microangiopathy (TMA) after kidney transplantation (KTx), particularly early onset de novo (dn) TMA, requires immediate interventions to prevent irreversible organ damage. This multicenter study was performed to investigate the allogeneic clinical factors and complement genetic background of dnTMA after KTx.

METHODS

Perioperative dnTMA after KTx within 1 week after KTx were diagnosed based on pathological or/and hematological criteria at each center, and their immunological backgrounds were researched. Twelve aHUS-related gene variants were examined in dnTMA cases.

RESULTS

Seventeen recipients (15 donors) were enrolled, and all dnTMA cases were onset within 72-h of KTx, and 16 of 17 cases were ABO incompatible. The implementation rate of pre-transplant plasmaphereses therapies were low, including cases with high titers of anti-A/anti-B antibodies. Examination of aHUS-related gene variants revealed some deletions and variants with minor allele frequency (MAF) in Japan or East Asian genome databases in genes encoding alternative pathways and complement regulatory factors. These variants was positive in 8 cases, 6 of which were positive in both recipient and donor, but only in one graft loss case.

CONCLUSIONS

Although some immunological risks were found for dnTMA after KTx, only a few cases developed into TMA. The characteristic variations revealed in the present study may be novel candidates related to dnTMA in Japanese or Asian patients, but not pathogenic variants of aHUS. Future studies on genetic and antigenic factors are needed to identify factors contributing to dnTMA after KTx.

The first successful case of ABO-incompatible living-donor lobar lung transplantation following desensitization therapy

ABO-incompatible (ABO-I) living-donor lobar lung transplantation (LDLLT) was successfully performed in a 14-year-old girl who suffered from bronchiolitis obliterans due to graft-versus-host disease following hematopoietic stem cell transplantation. In the ABO-I LDLLT procedure, the blood type O patient received a right lower lobe donated from her blood type B father and a left lower lobe donated from her blood type O mother. Desensitization therapy, using rituximab, immunosuppressants, and plasmapheresis, was implemented for 3 weeks prior to transplantation to reduce the production of anti-B antibodies in the recipient and prevent acute antibody-mediated rejection after ABO-I LDLLT.

Analysis of Risk Factors for Infusion-Related Reactions Following Rituximab Administration in Patients with Desensitization before Renal Transplantation

Infusion-related reactions (IRRs) are the major side effects of rituximab administration. Although several studies have reported predictive markers for IRRs in patients with malignancies, there are no such reports for patients without malignancies. Accordingly, we aimed to clarify the predictive markers for rituximab-induced IRRs in renal transplant recipients. This retrospective study included 116 inpatients aged ≥18 years who received an initial dose of 150 mg/m2 of rituximab for desensitization before renal transplantation with loxoprofen and diphenhydramine before rituximab infusion between June 2007 and February 2022. Overall, 45 patients were evaluated and 71 patients were excluded in this study. IRRs were observed in 12 (26.7%) patients. The proportion of men in the IRRs group was significantly higher than that in the non-IRRs group (p = 0.023). Additionally, body weight, body surface area (BSA), and body mass index (BMI) were significantly higher in the IRRs group than in the non-IRRs group (body weight, p = 0.0058; BSA, p = 0.0051; BMI, p = 0.017). Their cutoff values for predicting rituximab-induced IRRs, based on the receiver-operating characteristic curve, were 74.850 kg, 1.910 m2 and 24.164 kg/m2, respectively. In conclusion, the male sex, high actual body weight, BSA, and BMI may be new predictive markers for rituximab-induced IRRs in renal transplant recipients. Therefore, clinicians should carefully monitor patients who receive rituximab before renal transplantation and present with the predictive markers.

Overcoming limits: First ABO incompatible living donor paired kidney transplant in an hypersensitized pediatric recipient in Spain

INTRODUCTION

HLA sensitization is a growing problem in children awaiting kidney transplantation. In some cases, finding an immunologically compatible donor entails contemplating the option of an ABO incompatible transplant or paired transplant.

METHODS

Patient with genetic nephrotic syndrome and progressive chronic kidney disease, with a previous thrombosis of a first kidney transplant, resulting hypersensitized and remaining for a long-time on hemodialysis. Despite a desensitization strategy, family members were incompatible and deceased donation options must be ruled out due to the presentation of donor-specific antibodies (DSA). After 4 years, the possibility arises to perform a kidney paired transplant with a 62-year-old woman with an incompatible blood group. Although the current cytotoxicity- and cell-based crossmatches were negative, history of DSA were recorded.

RESULTS

An intensive ABO and HLA desensitization protocol was performed in order to combat the isohemagglutinin antibodies and on the memory-HLA, based on rituximab, apheresis sessions, and immunoglobulins. Despite the donor being older in terms of pediatric transplantation, the donor-recipient weight difference, and immunological risk, the transplant was completed successfully. Maintenance of titration of up to 1/2 was confirmed after 3 weeks post-transplant (IgM and IgG). Kidney biopsy at 2 weeks and 6 months without signs of rejection. The patient is currently 12 months post-transplant and has not presented any signs of transplant rejection and has proper renal function.

CONCLUSIONS

Kidney paired transplantation is an excellent solution for hypersensitized children, and ABO incompatibility can be considered to increase their options to find a good donor, without thereby obtaining worse results.

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.

ABO-incompatible living donor liver transplantation with high preoperative antibody titer: A case report

INTRODUCTION AND IMPORTANCE

ABO-incompatible living donor liver transplantation (ABOi-LDLT) is essential for expanding the donor pool. ABOi-LDLT prognosis has improved since desensitization treatment with rituximab; however, patients with high antibody titers are considered to be at high risk of antibody mediated rejection (AMR). Nevertheless, the preoperative antibody titer cutoff levels that preclude ABOi-LDLT have not yet been determined. In this study, the highest preoperative antibody titer was 1:4096, and the recipient had good outcomes. There has been only one report of good outcomes with a preoperative antibody titer of more than 1:4096. We hypothesized that high preoperative antibody titers in ABOi-LDLT may not be associated with AMR in protocols involving rituximab.

CASE PRESENTATION

The recipient was a 22-year-old man with biliary atresia and underwent ABOi-LDLT (B to O). We administered 500 mg of rituximab 14 days prior and then 300 mg of rituximab one day prior to ABOi-LDLT. The recipients preoperative IgG antibody titer was 1:4096. Postoperative immunosuppressive protocol involved steroids, tacrolimus, and mycophenolate mofetil. The patient had satisfactory graft function three years following ABOi-LDLT.

CLINICAL DISCUSSION

The antibody that is responsible for posttransplant AMR should be newly synthesized after transplantation as a result of sensitization by antigens on the vascular endothelial cells of the graft. In ABOi-LDLT, natural antibodies may not cause AMR.

CONCLUSIONS

The most important factor for preventing AMR in recipients undergoing ABOi-LDLT is the suppression of de novo antibodies. High preoperative antibody titers may not necessarily preclude ABOi-LDLT, provided that rituximab is used in desensitization.

Improved detection of donor-specific HLA-class II antibody in kidney transplant recipients by modified immunocomplex capture fluorescence analysis

Immunocomplex capture fluorescence analysis (ICFA) which basic principle is same as Luminex crossmatch (LXM), could detect donor-specific HLA antibody (DSA). The advantages of ICFA are (i) detection of DSA and (ii) no requirement of viable cells over the flow cytometry crossmatch (FCXM). However, FCXM has been widely used because of its higher sensitivity than ICFA, in particular HLA-class II antibody detection. In this study the accuracy of DSA detection against HLA-class II was investigated by modifying the original method of ICFA. Increment of the sensitivity was found when purified peripheral blood mononuclear cells (PBMCs) were used instead of whole blood. An ICFA-PBMC in addition to FCXM-T/B was conducted for 118 patients before kidney transplantation and 13 patients with de novo DSA against HLA-class II after transplantation. Significantly positive correlation was observed between the values of ICFA-PBMC and DSA mean fluorescence intensity (MFI) targeting class II (p < 0.0001). When the cutoff level of 1.4 was determined by receiver operating characteristic curve analysis, the average DSA MFI was found to be significantly higher in the ICFA-PBMC (class II) positive group comparing to that in the negative group (12,217 vs 3885, p = 0.0027). ICFA-PBMC and optimized cutoff level could provide valid information in cases of suspected DSA.

[How to implement a complete apheresis program within a hemodialysis unit]

Many apheresis techniques can be performed in a blood-bank facility or a hemodialysis (HD) facility. However, it makes sense to perform apheresis in a hemodialysis facility as apheresis involves extra-corporeal circuits and because HD can be performed at the same time as apheresis (tandem procedure). Apheresis techniques comprise therapeutic plasma exchange, double-filtration plasmapheresis, and its derivative (rheopheresis and LDL-apheresis), and immunoadsorption (specific and semi-specific). We have setup an apheresis platform in our hospital that fulfills health recommendations. This process has involved financial investment and significant human resources, and has enabled us to network with different specialties (neurology, hematology, vascular medicine). We have setup protocols according to the type of pathology to be treated by apheresis, and to monitor clinical and biological data for each apheresis session. The main side effects of apheresis are a fall in blood pressure when a session is initiated, an increase in fluid overload, hypocalcemia, and the loss of some essential plasmatic factors. However, these side-effects are easily identified and can be properly managed in real time. Within two-years, we have performed 1845 apheresis sessions (134 patients). Of these, 66 received apheresis before and/or after kidney transplantation for ABO and/or HLA incompatibility (desensitization), for humoral rejection, or in the setting of relapsing focal-segmental glomerulosclerosis. Our patients' outcomes have been similar to those reported in the literature. The other 68 patients had various conditions. Because our program is now well-established, we are currently forming a specialist center to train physicians and nurses in the various apheresis techniques/procedures.

Association between response to rituximab and antibody-mediated rejection in ABO-incompatible living kidney transplantation

OBJECTIVES

To examine the association of response to rituximab and the incidence of antibody-mediated rejection in preconditioning of rituximab and plasma exchange without post-transplant plasmapheresis in patients undergoing ABO-incompatible living kidney transplantation.

METHODS

A total of 115 patients who underwent ABO-incompatible living kidney transplantation at Tokyo Women's Medical University Hospital, Tokyo, Japan, were divided into two groups based on the response to rituximab: good response (n = 75) or poor response (n = 40). The rituximab good response and poor response patients were defined as patients whose CD19⁺ cells were non-detected (0%) and detected on the day of transplantation (2-5 days, median 3 days, after rituximab administration), respectively.

RESULTS

Rituximab response and anti-A/B blood antibody titer after plasmapheresis were significant risk factors for antibody-mediated rejection (P = 0.036, 0.045, respectively). The occurrence of antibody-mediated rejection was higher in the poor response group than in the good response group (22.5% vs 8.0%; P = 0.028). The 14-day, 3-month and 1-year cumulative incidence of antibody-mediated rejection was 2.7%, 5.3% and 8.0% in the good response group, and 17.5%, 20.0% and 22.5% in the poor response group after ABO-incompatible living kidney transplantation. The patient survival was not significantly different between the two groups. However, graft survival 1 month after transplantation was lower in the poor response group. There is no significant difference in graft function and in the incidence of complications, including infection, after transplantation between the two groups.

CONCLUSIONS

Antibody-mediated rejection after ABO-incompatible living kidney transplantation was significantly associated with the response to rituximab in our preconditioning protocol.

Association Between Peripheral Blood CD19-Positive Rate and Antibody-Mediated Rejection Following Rituximab Administration in Kidney Transplant Recipients

Background.

Rituximab is used widely for desensitization in ABO-incompatible and donor-specific antibody-positive kidney transplantation. However, data about the effects of individual differences in rituximab-induced B-cell suppression on antibody-mediated rejection (AMR) remain unknown. We aimed to assess the association between CD19-positive rate and AMR following rituximab administration after kidney transplantation.

Methods.

Overall, 42 patients who underwent rituximab therapy for pretransplant desensitization in ABO-incompatible (n = 33) and donor-specific antibody-positive (n = 15) kidney transplantation were observed retrospectively. To predict AMR incidence, the peripheral blood CD19-positive rate was determined and classified into short- and long-acting groups. AMR incidence, allograft function, complications, and rituximab dose were compared.

Results.

Eight patients (19%) had AMR within 39.2 months after transplantation. The CD19-positive rate cutoff value to predict AMR incidence was 4.4%, 6.4%, and 7.7% at 6, 12, and 18 months after transplantation, respectively. When comparing the short- and long-acting groups stratified according to the CD19-positive rate cutoff value, AMR incidence was significantly higher in the short-acting group than in the long-acting group at 6 (71.4% vs 8.6%), 12 (70.0% vs 3.1%), and 18 (58.3% vs 3.3%) months after transplantation. The CD19-positive rate for all patients with AMR exceeded the cutoff value 6, 12, or 18 months. Conversely, serum creatinine level, tacrolimus trough-level, cytomegalovirus antigenemia-positive rate, neutropenia incidence rate, and total dose of rituximab before transplantation showed no significant differences between the 2 groups.

Conclusions.

The risk of AMR was higher in patients with short-term B-cell suppression following rituximab administration. Additional rituximab administration after transplantation may prevent AMR in patients with a CD19-positive rate higher than the cutoff value.