Clinical significance of isoagglutinin titre with the current desensitization protocol in ABO-incompatible kidney transplantation

Long-term isoagglutinin monitoring after ABO-incompatible kidney transplantation

OBJECTIVES

This study aimed to evaluate whether a 2-week period of daily isoagglutinin titer testing after ABO-incompatible kidney transplantation (ABOi-KT) is sufficient to ensure successful engraftment and to advocate for an extension of the monitoring duration in specific situations.

METHODS

We reviewed patients from January 2022 to December 2023 at Asan Medical Center who underwent therapeutic plasma exchange (TPE) due to elevated ABO antibody titers and suspected acute antibody-mediated rejection (AMR) after ABOi-KT. Data collected included pre- and posttransplantation laboratory results, clinical and procedural information, imaging studies, and needle biopsy results of the renal graft.

RESULTS

We encountered 3 cases of acute AMR 2 weeks after transplantation. All cases exhibited simultaneous increases in anti-ABO antibody isoagglutinin titers, creatinine, and C-reactive protein levels. Clinical signs, including fever, suggested possible infection, and renal graft biopsy, confirmed AMR in all cases. Two cases underwent graftectomy, while the third recovered renal function after conservative treatment, including TPE.

CONCLUSIONS

Our findings suggest that a 2-week monitoring period for isoagglutinin titers after ABOi-KT may not be sufficient to detect late AMR. Extending the monitoring duration and considering lifelong fresh-frozen plasma transfusion with graft-compatible blood types, along with periodic isoagglutinin titer testing in cases of suspected AMR, may improve long-term graft outcomes.

A comparative study on outcomes of ABO-incompatible kidney transplants between robot-assisted vs. open surgery-propensity score-matched analysis: a retrospective cohort study

BACKGROUND

Robot-assisted kidney transplantation (RAKT) is increasingly being adopted worldwide. Despite this growing interest, there remains a notable gap in the literature, especially concerning its effectiveness in immunologically high-risk patients compared to conventional open kidney transplantation (OKT). This study investigates the viability and success of RAKT in comparison with OKT, particularly for recipients with ABO incompatibility (ABOi).

METHODS

This retrospective, single-center study included 239 living-donor transplants between October 2020 and February 2023, with 210 patients undergoing ABOi-OKT and 29 undergoing ABOi-RAKT. A composite of biopsy-proven acute rejection (BPAR), graft failure, and the development of de novo donor-specific antibodies was analyzed through univariate and multivariate models. Propensity score matching (PSM) was utilized to ensure a balanced comparison between the two groups. Following PSM, a total of 131 cases in the OKT group and 26 cases in the RAKT group were analyzed.

RESULTS

After PSM, the mean recipient age was 48.56 years for OKT and 47.96 years for RAKT. Both groups had comparable one-year (RAKT: 92.4%, OKT: 93.1%) and two-year BPAR-free survival rates (RAKT: 92.4%, OKT: 91.9%). Mean estimated glomerular filtration rate values were similar at 12 months post-transplant (RAKT: 62.15 ml/min/1.73 m², OKT: 64.53 ml/min/1.73 m²). Operative times were significantly longer for RAKT (291.42 vs. 150.81 min, p < 0.001), while cold ischemic time was also longer for RAKT (119.77 vs. 47.22 min, p < 0.001). Hospital stays were shorter for RAKT (median 6 vs. 8 days, p < 0.001). There was no significant difference in the composite outcome of BPAR, graft failure, and de novo donor-specific antibodies between the two groups (HR 0.858, 95% CI: 0.180-4.096, p = 0.848).

CONCLUSIONS

RAKT is a safe and effective alternative to OKT in ABOi patients, demonstrating similar perioperative outcomes, graft survival rates, and renal function. The application of ropensity score matching analysis strengthens the reliability of these findings, confirming RAKT's viability for high-risk kidney transplant recipients.

TRIAL REGISTRATION

The clinical trial associated with this study was registered on 2024-02-24 with the Clinical Trial Number NCT06287008|| https://www.

CLINICALTRIALS

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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.

Transplant outcomes of 100 cases of living-donor ABO-incompatible kidney transplantation

BACKGROUND

Although ABO-incompatible (ABOi) kidney transplantation (KT) has been performed successfully, a standard preconditioning regimen has not been established. Based on the initial antidonor ABO antibody titers, an individualized preconditioning regimen is developed, and this study explored the efficacy and safety of the regimen.

METHODS

From September 1, 2014, to September 1, 2020, we performed 1668 consecutive living-donor KTs, including 100 ABOi and 1568 ABO-compatible (ABOc) KTs. ABOi KT recipients (KTRs) with a lower antibody titer (≤1:8) were administered oral immunosuppressive drugs (OIs) before KT, while patients with a medium titer (1:16) received OIs plus antibody-removal therapy (plasma exchange/double-filtration plasmapheresis), patients with a higher titer (≥1:32) were in addition received rituximab (Rit). Competing risk analyses were conducted to estimate the cumulative incidence of infection, acute rejection (AR), graft loss, and patient death.

RESULTS

After propensity score analyses, 100 ABOi KTRs and 200 matched ABOc KTRs were selected. There were no significant differences in graft and patient survival between the ABOi and ABOc groups (P  = 0.787, P  = 0.386, respectively). After using the individualized preconditioning regimen, ABOi KTRs showed a similar cumulative incidence of AR (10.0% υs . 10.5%, P  = 0.346). Among the ABOi KTRs, the Rit-free group had a similar cumulative incidence of AR ( P  = 0.714) compared to that of the Rit-treated group. Multivariate competing risk analyses revealed that a Rit-free regimen reduced the risk of infection (HR: 0.31; 95% CI: 0.12-0.78, P  = 0.013). Notably, antibody titer rebound was more common in ABOi KTRs receiving a Rit-free preconditioning regimen ( P  = 0.013) than those receiving Rit. ABOi KTRs with antibody titer rebound had a 2.72-fold risk of AR (HR: 2.72, 95% CI: 1.01-7.31, P  = 0.048). ABOi KTRs had similar serum creatinine and estimated glomerular filtration rate compared to those of ABOc KTRs after the first year.

CONCLUSIONS

An individualized preconditioning regimen can achieve comparable graft and patient survival rates in ABOi KT with ABOc KT. Rit-free preconditioning effectively prevented AR without increasing the risk of infectious events in those with lower initial titers; however, antibody titer rebound should be monitored.

Isoagglutinin Titers in ABO-Incompatible Kidney Transplant

BACKGROUND

A decrease in the isoagglutinin titer <1:8 is usually required for ABO-incompatible (ABOi) transplantation and the presence of high predesensitization titers may condition future transplantation. The aim of the study was to analyze the prognosis of ABOi patients undergoing desensitization and to compare the results according to the baseline isoagglutinin titer.

METHODS

ABOi patients transplanted in our center after desensitization with rituximab, apheresis (plasmapheresis, immunoadsorption with Glycosorb, or both) and immunoglobulins were studied. Survival, renal function, and complications were analyzed and the results were compared according to the presence of a baseline isoagglutinin titer higher or lower than 1:128. We analyzed 48 patients (34 male) with a mean age of 50.9 ± 11 years and a mean follow-up of 44.6 ± 30 months. Thirty-eight patients had a basal isoagglutinin titer ≤1:128 and 10 had a titer >1:128. We did not observe differences in patient survival: 96% vs 100% at 5 years (P = .64) and renal survival: 91% vs 100% at 5 years (P = .39), incidence of acute rejection: 13.2% vs 0% (P = .22), infectious complications (cytomegalovirus; 16% vs 30%, P = 0.30; Polyomavirus BK virus: 13% vs 0%, P  =  .22), or surgical (hematoma): 47% vs 60% (P = .47) between the 2 groups. A higher number of apheresis sessions was observed (4.8 ± 1.9 vs 10.9 ± 3.9; P = .001); use of both techniques (0% vs 100%, P < .001) and higher processed volume (1 ± 0.1 vs 1.4 ± 0.5; P = .049) in patients with titer >128 was observed. Creatinine and proteinuria were similar and not significant.

CONCLUSIONS

Baseline isoagglutinin titer does not influence the prognosis of ABOi patients after desensitization. The number of sessions required to achieve baseline titer <1:8 is higher but does not influence the number of days of hospital admission.

Acute Rejection and Infectious Complications in ABO- and HLA-Incompatible Kidney Transplantations

Background

Patients receiving ABO-incompatible (ABOi) or human leukocyte antigen (HLA)-incompatible (HLAi) kidney transplantation (KT) require potent immunosuppression and are thus at a higher risk of infectious complications. We evaluated the clinical outcomes of KT stratified by ABO and HLA incompatibilities and identified the factors associated with the clinical outcomes.

Material/Methods

Recipients who underwent living-related KT between 2012 and 2017 were included and classified into 4 groups: ABO-compatible and HLA-compatible (ABOc/HLAc), HLA-incompatible (ABOc/HLAi), ABO-incompatible (ABOi/HLAc), and ABO-incompatible and HLA-incompatible (ABOi/HLAi). Cox proportional hazards regression analyses were carried out to evaluate the risk factors of acute rejection. Out of the 1732 patients who underwent KT, 1190, 131, 358, and 53 were in the ABOc/HLAc, ABOi/HLAc, ABOc/HLAi, and ABOi/HLAi groups, respectively.

Results

The ABO/HLAi group showed the lowest 5-year graft survival rate (91.7%). Death-censored graft survival was not significantly different among the groups. The mortality rate from infections was significantly higher in the ABOi/HLAi group (7.5%) than the other groups. Antibody-mediated rejection-free graft survival was the lowest in the ABOi/HLAi group, with significant differences compared with the ABOi/HLAc group (P=0.02) and the ABOc/HLAi group (P=0.03). ABOi/HLAi (hazard ratio [HR], 2.63; 95% confidence interval [CI], 1.04–6.65; P<0.01) and combined infection (HR, 1.91; 95% CI, 1.45–2.51; P<0.01) were significant risk factors for acute rejection.

Conclusions

Patients with both ABO and HLA incompatibilities showed inferior rates of overall patient and graft survival due to infectious complications. Infection was a prominent risk factor of acute rejection following KT after adjusting for possible confounders including ABO and HLA incompatibility.