Outcome of ABO Blood Type-Incompatible Living-Related Donor Kidney Transplantation Under a Contemporary Immunosuppression Strategy in Japan

Efficacy of valganciclovir prophylaxis in kidney transplant recipients following low-dose rituximab induction therapy: a multicenter retrospective study

BACKGROUND

Rituximab (RIT) induction therapy is widely used for desensitization against ABO-incompatible living-donor kidney transplants (KT). However, the efficacy of valganciclovir (VGCV) prophylaxis against cytomegalovirus (CMV) disease and infection in KT recipients (KTRs) following RIT induction remains unclear.

METHODS

The current multicenter retrospective study included 213 KTRs who received low-dose RIT induction between 1998 and 2021, across 6 facilities included in the Michinoku Renal Transplant Network (MRTN). VGCV dosage varied from 450 mg/day (twice weekly) to 900 mg/day (daily), with treatment durations of 3-12 months. The primary and secondary endpoints were the incidence of CMV disease and infection, respectively.

RESULTS

The incidence of CMV disease was significantly higher in the VGCV group (23.5%; 16 patients) than in the non-VGCV group (5.5%; 8 patients) (p < 0.01). The incidence of CMV infection was 54.5% (79 patients) in the non-VGCV group and 48.5% (33 patients) in the VGCV group, with no significant difference (p = 0.42). In the subgroup of CMV-seronegative KTRs receiving allografts from CMV-seropositive donors (CMV IgG (D + /R-)), 18 out of 24 KTRs received VGCV prophylaxis, of whom 10 (55.6%) developed CMV disease. Within this subgroup, only 4 KTRs received VGCV with the standard protocol (900 mg daily for 6 months), and none developed CMV disease.

CONCLUSION

Insufficient VGCV prophylaxis does not reduce the incidence of CMV disease in KTRs following low-dose RIT induction. Despite concerns about leukopenia due to RIT and VGCV, in KTRs with CMV IgG (D + /R-) serostatus, VGCV prophylaxis with a standard protocol may be advisable.

Outcomes in AB0 Incompatible Living Donor Kidney Transplantation: A Case – Control Study

Background

Patients waiting for a kidney transplant by far exceed available organs. AB0 incompatible living donor kidney transplantation (AB0i LDKT) represents an additional therapeutic strategy, but with higher risk for complications. We aimed at evaluating outcomes of AB0i LDKTs compared to compatible (AB0c) controls at our Institution.

Methods

Retrospective matched case – control study (1:2) comparing AB0i vs. AB0c LDKTs from March 2012 to September 2021. Considered outcomes: graft function, acute rejection, sepsis, CMV infection, BK virus reactivation, death-censored graft survival, patient survival.

Results

Seventeen AB0i LDKTs matched to 34 AB0c controls. We found excellent graft function, comparable in the two groups, at all considered intervals, with an eGFR (ml/min/1.73 m2) of 67 vs. 66 at 1 year (p = 0.41), 63 vs. 64 at 3 years (p = 0.53). AB0i recipients had a statistically significant higher incidence of acute rejection, acute antibody-mediated rejection and sepsis within 30 days (p = 0.016; p = 0.02; p = 0.001), 1 year (p = 0.012; p = 0.02; p = 0.0004) and 3 years (p = 0.004; p = 0.006; p = 0.012) after surgery. There was no difference in CMV infection, BK virus reactivation, death-censored graft survival between the two groups. Patient survival was inferior in AB0i group at 1 and 3 years (88.2 vs. 100%; log-rank p = 0.03) due to early death for opportunistic infections. AB0i LDKTs spent longer time on dialysis (p = 0.04) and 82.3 vs. 38.3% controls had blood group 0 (p = 0.003).

Conclusions

AB0i LDKT is an effective therapeutic strategy with graft function and survival comparable to AB0c LDKTs, despite higher rates of acute rejection and sepsis. It is an additional opportunity for patients with less chances of being transplanted, as blood group 0 individuals.

Seroprevalence of SARS-CoV-2 spike IgG antibodies after the second BNT162b2 mRNA vaccine in Japanese kidney transplant recipients

We aimed to evaluate the seroprevalence and investigated factors associated with seropositivity after the second SARS-CoV-2 mRNA vaccination in kidney transplant (KT) recipients. This retrospective study conducted between June and November 2021 included 106 KT recipients and 127 healthy controls who received the second dose of the BNT162b2 mRNA vaccine at least 7 days before the measurement of antibody titers. The antibody titer against the receptor-binding domain of SARS-CoV-2 spike (S) protein was determined. We compared seroprevalence rates (immunoglobulin G [IgG] level of ≥ 0.8 or ≥ 15 U/mL) between the healthy controls and KT recipients and identified factors associated with impaired humoral response. The seroprevalence rate of the healthy controls and KT recipients was 98% and 22%, respectively. Univariate logistic regression analysis revealed that age > 53 years, rituximab use, mycophenolate mofetil use, and KT vintage < 7 years were negatively associated with the rate of anti-SARS-CoV-2 S IgG ≥ 15 U/mL in KT recipients. ABO blood type incompatible KT was not significantly associated with seroprevalence. Humoral response after the second BNT162b2 mRNA vaccine was greatly hindered by immunosuppression therapy in KT recipients. Older age, rituximab use, mycophenolate mofetil use, and KT vintage may play key roles in seroconversion.

Infection Risk in the First Year After ABO-incompatible Kidney Transplantation: A Nationwide Prospective Cohort Study

BACKGROUND

ABO-incompatible (ABOi) kidney transplantation (KT) expands the kidney donor pool and may help to overcome organ shortage. Nonetheless, concerns about infectious complications associated with ABOi-KT have been raised.

METHODS

In a nationwide cohort (Swiss Transplant Cohort Study), we compared the risk for infectious complications among ABOi and ABO-compatible (ABOc) renal transplant recipients. Infections needed to fulfill rigorous, prespecified criteria to be classified as clinically relevant. Unadjusted and adjusted competing risk regression models were used to compare the time to the first clinically relevant infection among ABOi-KT and ABOc-KT recipients. Inverse probability weighted generalized mixed-effects Poisson regression was used to estimate incidence rate ratios for infection.

RESULTS

We included 757 living-donor KT recipients (639 ABOc; 118 ABOi) and identified 717 infection episodes. The spectrum of causative pathogens and the anatomical sites affected by infections were similar between ABOi-KT and ABOc-KT recipients. There was no significant difference in time to first posttransplant infection between ABOi-KT and ABOc-KT recipients (subhazard ratio, 1.24; 95% confidence interval [CI], 0.93-1.66; P = 0.142). At 1 y, the crude infection rate was 1.11 (95% CI, 0.93-1.33) episodes per patient-year for ABOi patients and 0.94 (95% CI, 0.86-1.01) for ABOc-KT recipients. Inverse probability weighted infection rates were similar between groups (adjusted incidence rate ratio, 1.12; 95% CI, 0.83-1.52; P = 0.461).

CONCLUSIONS

The burden of infections during the first year posttransplant was high but not relevantly different in ABOi-KT and ABOc-KT recipients. Our results highlight that concerns regarding infectious complications should not affect the implementation of ABOi-KT programs.