Determination of Rituximab Dose According to Immunologic Risk in ABO-Incompatible Kidney Transplantation

Long-Term Outcome of ABO-Incompatible Kidney Transplantation in Patients Treated With Low-Dose Rituximab Regimen

BACKGROUND

Introduction of rituximab in the desensitization protocols for ABO-incompatible (ABOI) kidney transplantation (KTX) has afforded excellent results. However, the acceptability of minimal dosage of rituximab in these protocols remains to be defined.

METHODS

Sixty-three patients who underwent ABOI KTX were included in this study. The desensitization protocol consisted of plasmapheresis, tacrolimus, mycophenolate mofetil, methylprednisolone, intravenous immunoglobulin, basiliximab, and low-dose rituximab (100 mg/body). We evaluated the efficacy, safety, and long-term outcome of this protocol (group R, n = 39) and compared them with those of patients who underwent splenectomy (group S, n = 24).

RESULTS

Graft and patient survival at 10 years after KTX were comparable between the groups (94.4% [group R] vs 95.4% [group S] and 94.6% [group R] vs 95.8% [group S], respectively). The incidence of acute antibody-mediated rejection (AAMR) was similar in the 2 groups (10.2% vs 12.5%). There were no significant differences in the incidence of chronic active antibody-mediated rejection. Of the patients, 7 developed AAMR and 3 of these patients (1 in group R and 2 in group S) lost their grafts. There were no significant differences in the incidence of chronic active antibody-mediated rejection. The incidence of postoperative cytomegalovirus infection in group R was significantly lower than that in group S. Furthermore, the incidence of postoperative late-onset neutropenia was low in group R.

CONCLUSIONS

A low-dose rituximab regimen for ABOI KTX is acceptable for preventing AAMR with a low incidence of delayed adverse events.

Effect of Different Rituximab Doses on B Cell Count, Anti-A/B Antibody Titer, Graft Function, and Infectious Complications in ABO-Incompatible Renal Transplantation: A Prospective Study

BACKGROUND

ABO-incompatible kidney transplantation (ABOiKT) has been accepted as a viable and cost-effective modality with outcomes comparable to ABO-compatible transplants, but there is a concern regarding higher infectious complications in ABOiKT because of the heightened immunosuppression. The desensitization protocol normally includes antibody removal, B cell depletion by rituximab (RTX), and immunomodulation with intravenous immunoglobulin. Efforts have been made over the years to decrease the dose of RTX in an effort to decrease the infective complications. There is limited literature about the minimum effective dose of RTX, which can cause an effective B cell depletion. This prospective study was designed to correlate the RTX dose with peripheral absolute B cell count, graft function, graft and patient survival, and infective complications.

METHODS

This study included 52 adult ABOiKT recipients with anti-A/B antibody titer up to a maximum of 1:512. The participants were divided into 2 groups of 26 each according to the RTX dosage used: Group A received 100 mg/patient, and Group B received 200 mg/patient. RTX was given 14 days prior to transplant after B cell measurement by flow cytometry. The outcomes were compared after 1 year of follow-up.

RESULTS

Both the dosages effectively depleted the absolute B cell count. Although patient survivals, graft survival, graft function, acute rejection episodes, and post-transplant hospital stay were similar in both groups, infective complications were significantly higher in group B.

CONCLUSION

A low dose (100 mg/patient) of RTX produces effective depletion of B cells while lowering the infective complications in ABOiKT.

Clinical outcomes of ABO- and HLA-incompatible kidney transplantation: a nationwide cohort study

This was a nationwide cohort study to investigate the impact of anti-A/B and donor-specific anti-HLA (HLA-DSA) antibodies on the clinical outcomes in kidney transplant recipients (KTRs). We classified a total of 1964 KTRs into four groups: transplants from ABO-incompatible donors (ABOi, n = 248); transplants in recipients with HLA-DSA (HLAi, n = 144); transplants from combined ABOi and HLAi donors (ABOi + HLAi, n = 31); and a control group for whom neither ABOi nor HLAi was applicable (CONT, n = 1541). We compared the incidence of biopsy-proven acute rejection (BPAR), allograft and patient survival rates. The incidence of BPAR was higher in the HLAi and ABOi + HLAi groups relative to the CONT group; in contrast, it was not higher in the ABOi group. Death-censored graft survival rates did not differ across the four groups. However, relative to the CONT group, patient survival rate was reduced in the ABOi and ABOi + HLAi groups, and with infection being the most common cause of death. Further, multivariable analysis revealed that desensitization therapy because of ABOi or HLAi was independent risk factors for patient mortality. HLAi was a more important risk factor for BPAR compared with ABOi. However, pretransplant desensitization therapy for either ABOi or HLAi significantly increased the risk of infection-related mortality.

Impact of ABO incompatible kidney transplantation on living donor transplantation

Background

ABO incompatible kidney transplantation (ABOi-KT) is an important approach for overcoming donor shortages. We evaluated the effect of ABOi-KT on living donor KT.

Methods

Two nationwide transplantation databases were used. We evaluated the impact of ABOi-KT on overall living donor transplant activity and spousal donation as subgroup analysis. In addition, we compared the clinical outcome between ABOi-KT and ABO compatible KT (ABOc-KT) from spousal donor, and performed a Cox proportional hazards regression analysis to define the risk factors affecting the allograft outcomes.

Result

The introduction of ABOi-KT increased overall living donor KT by 12.2% and its portion was increased from 0.3% to 21.7% during study period. The ABOi-KT in living unrelated KT was two times higher than that of living related donor KT (17.8 vs.9.8%). Spousal donor was a major portion of living unrelated KT (77.6%) and ABOi-KT increased spousal donation from 10% to 31.5% in living donor KT. In addition, increasing rate ABOi-KT from spousal donor was 10 times higher than that of living related donor. The clinical outcome (incidence of acute rejection, allograft function, and allograft and patient survival rates) of ABOi-KT from spousal donor was comparable to that of ABOc-KT. Neither ABO incompatibility nor spousal donor was associated with acute rejection or allograft failure on multivariate analysis.

Conclusions

ABOi-KT increased overall living donor KT, and ABOi-KT from spousal donor is rapidly increasing with favorable clinical outcomes.

Single-Center Experience of ABO-Incompatible Living-Donor Liver Transplantation With a New Simplified Intravenous Immunoglobulin Protocol: A Propensity Score-Matching Analysis

The outcomes of patients who undergo ABO-incompatible (ABO-I) living-donor liver transplantation (LDLT) have markedly improved as strategies have become more innovative and advanced. Here, we describe 25 cases of ABO-I LDLT with a simplified protocol and compare the outcomes to those of ABO-compatible LDLT. We analyzed outcomes via a retrospective review of 182 adult LDLT cases including 25 ABO-I LDLTs from January 2011 to December 2014. Propensity scoring was used to compare the groups. The desensitization protocol included plasma exchange, rituximab, and intravenous immunoglobulin without local infusion therapy. The triple immunosuppression protocol consisted of tacrolimus and steroids with mycophenolate mofetil; a splenectomy was not routinely performed. The median age of recipients was 51 years (range, 35-66 years), and the median mean Model for End-Stage Liver Disease (MELD) score was 15 (range, 7-37). The initial ranges of isoagglutinin IgM and IgG titers were 1:1 to 1:256 and 1:4 to 1:2048, respectively. There were no significant differences in patient demographics or perioperative variables between the groups. Although significant rebound elevation in anti-ABO antibody during the postoperative period was observed in 3 cases, neither C4d staining nor clinical signs of antibody-mediated rejection was apparent in these cases. No diffuse intrahepatic biliary stricture was encountered in any ABO-I LDLT patient within a mean follow-up of 22.6 ± 17.2 months. Moreover, no significant difference in overall or graft survival was observed between the groups. ABO-I LDLT can be performed safely under this new simplified protocol and may be proposed when ABO-compatible donors are unavailable.

Impact of ABO Incompatibility on the Development of Acute Antibody-Mediated Rejection in Kidney Transplant Recipients Presensitized to HLA

Whether the coexistence of anti-A/B antibody and donor specific anti-HLA antibody (HLA-DSA) has a synergistic impact on the development of acute antibody-mediated rejection (AAMR) in kidney transplant recipients (KTRs) is unclear. This study includes 92 KTRs who received a kidney from an ABO-incompatible (ABOi) donor or were presensitized to donor HLA (HLAs) and 292 controls (CONT). HLAs was defined as a crossmatch positivity or the presence of HLA-DSA. We compared the incidence of AAMR among ABOi (n = 58), ABOi+HLAs (n = 12), HLAs (n = 22), and CONT (n = 292) groups and evaluated the risk factors and antibody type (anti-A/B vs. HLA-DSA) responsible for AAMR. AAMR developed less frequently in ABOi and CONT than in the ABOi+HLAs or HLAs (P < 0.05 for all); however, there was no difference between the ABOi+HLAs and HLAs groups. AAMR developed more frequently with strong HLA-DSA at baseline; however, high baseline anti-A/B titer did not affect AAMR development. Strong baseline HLA-DSA was an independent predictor for AAMR, however the baseline anti-A/B titer was not. All four AAMR episodes in ABOi+HLAs were positive to HLA-DSA but not to anti-A/B. In conclusion, ABO incompatibility does not increase the risk for AAMR in HLAs KTRs.

Fourteen successful consecutive cases of ABO-incompatible living donor liver transplantation: new simplified intravenous immunoglobulin protocol without local infusion therapy

Since various innovative strategies including local infusion therapy and rituximab have been introduced, the survivals and outcomes of recipients in ABO-incompatible (ABO-I) living donor liver transplantation (LDLT) have remarkably improved. Thus, ABO-I LDLT can be a feasible therapeutic option for the patient with end-stage liver disease if an ABO-compatible donor is not available. Although most ABO-I protocols are based on rituximab, plasma exchange, and local infusion therapy, treatment strategies have been changing according to a center's preference or their results. Nonetheless, the consensus of the ABO-I LDLT protocol remains undetermined. Herein, we present our experience with new simple ABO-I LDLT protocol and the excellent results for 14 patients from January 2011 to May 2013. All patients were administrated a single dose of rituximab over 7 days before transplantation followed by plasma exchange to lower anti-ABO antibody titer ≤32. The basic immunosuppression protocol consisted of tacrolimus and steroids with mycophenolate mofetil starting 3 days before transplantation. Splenectomy was not performed routinely and local infusion therapy was not applied at the postoperative period. Instead, the patients received intravenous immunoglobulin (IVIG) after LDLT on days 1, 3, and 5. Neither antibody-mediated rejection nor biliary stricture were encountered in the patients, with a mean follow-up of 16.27 ± 9.4 months. This new simplified ABO-I LDLT protocol seems to prevent antibody-mediated rejection and could be considered as the safe and effective modality to overcome the ABO blood-type barrier in LDLT.

Impact of the baseline anti-A/B antibody titer on the clinical outcome in ABO-incompatible kidney transplantation

BACKGROUND/AIMS

We investigated the impact of the baseline anti-A/B antibody titer on the clinical outcome in ABO-incompatible kidney transplantation (IKT).

METHODS

We included 183 patients who had undergone KT (40 ABO IKT and 143 ABO-compatible KT). Eight patients with a baseline titer of ≥1:512 were assigned to the high-titer group and 32 patients with a baseline titer of ≤1:256 were assigned to the low-titer group. Patients who underwent ABO-compatible KT were used as the control group. We compared the clinical outcomes of the three groups.

RESULTS

Before transplantation, the high-titer group displayed more frequent antibody rebound, as shown in a lower titer reduction rate, and more difficulty reaching the target titer (1:16) than the low-titer group. During the postoperative period and out-clinic follow-up, antibody rebound was more frequent, and the rate of acute rejection and infection were significantly higher and allograft function was lower in the high-titer group than in the low-titer and control groups. Multivariate analysis showed that high baseline antibody titer was an independent risk factor for acute rejection.

CONCLUSION

ABO IKT in the high-titer group (baseline titer ≥1:512) required greater caution compared to the low-titer group because of the higher tendency of antibody rebound and the risk for acute rejection.