Anti-B cell therapy with rituximab as induction therapy in renal transplantation

Single fixed low-dose rituximab as induction therapy suppresses de novo donor-specific anti-HLA antibody production in ABO compatible living kidney transplant recipients

This study was conducted to evaluate de novo donor-specific anti-human leukocyte antigen (HLA) antibody (dnDSA) production leading to antibody-mediated rejection (ABMR) after rituximab induction in non-sensitized ABO-compatible living kidney transplantation (ABO-CLKTx). During 2008-2015, 318 ABO-CLKTx were performed at the Department of Surgery III at Tokyo Women's Medical University Hospital. To reduce confounding factors, we adopted a propensity score analysis, which was applied with adjustment for age, gender, duration of pretransplant dialysis, HLA mismatch count, preformed DSA, non-insulin-dependent diabetes mellitus, immunosuppressive treatment, and estimated glomerular filtration rate (eGFR) on postoperative day 7. Using a propensity score matching model (1:1, 115 pairs), we analyzed the long-term outcomes of 230 ABO-CLKTx recipients retrospectively. Recipients were classified into a rituximab-treated (RTX-KTx, N = 115) group and a control group not treated with rituximab (C-KTx, N = 115). During five years, adverse events, survival rates for grafts and patients, and incidence of biopsy-proven acute rejection (BPAR) and dnDSA production for the two groups were monitored and compared. All recipients in the RTX-KTx group received rituximab induction on preoperative day 4 at a single fixed low dose of 100 mg; the CD19+ B cells were eliminated completely before surgery. Of those recipients, 13 (11.3%) developed BPAR; 1 (0.8%) experienced graft loss. By contrast, of C-KTx group recipients, 25 (21.7%) developed BPAR; 3 (2.6%) experienced graft loss. The RTX-KTx group exhibited a significantly lower incidence of BPAR (P = .041) and dnDSA production (13.9% in the RTX-KTx group vs. 26.9% in the C-RTx group, P = .005). Furthermore, lower incidence of CMV infection was detected in the RTX-KTx group than in the C-KTx group (13.9% in the RTX-KTx group vs. 27.0% in the C-KTx group, P = .014). No significant difference was found between groups for several other factors: renal function (P = .384), graft and patient survival (P = .458 and P = .119, respectively), and the respective incidences of BK virus infection (P = .722) and leukopenia (P = .207). During five-year follow-up, single fixed low-dose rituximab therapy is sufficient for ensuring safety, reducing rejection, and suppressing dnDSA production for immunological low-risk non-sensitized ABO-CLKTx.

Polyclonal and monoclonal antibodies for induction therapy in kidney transplant recipients

BACKGROUND

Prolonging kidney transplant survival is an important clinical priority. Induction immunosuppression with antibody therapy is recommended at transplantation and non-depleting interleukin-2 receptor monoclonal antibodies (IL2Ra) are considered first line. It is suggested that recipients at high risk of rejection should receive lymphocyte-depleting antibodies but the relative benefits and harms of the available agents are uncertain.

OBJECTIVES

We aimed to: evaluate the relative and absolute effects of different antibody preparations (except IL2Ra) when used as induction therapy in kidney transplant recipients; determine how the benefits and adverse events vary for each antibody preparation; determine how the benefits and harms vary for different formulations of antibody preparation; and determine whether the benefits and harms vary in specific subgroups of recipients (e.g. children and sensitised recipients).

SEARCH METHODS

Randomised controlled trials (RCTs) comparing monoclonal or polyclonal antibodies with placebo, no treatment, or other antibody therapy in adults and children who had received a kidney transplant.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing monoclonal or polyclonal antibodies with placebo, no treatment, or other antibody therapy in adults and children who had received a kidney transplant.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. Dichotomous outcomes are reported as relative risk (RR) and continuous outcomes as mean difference (MD) together with their 95% confidence intervals (CI).

MAIN RESULTS

We included 99 studies (269 records; 8956 participants; 33 with contemporary agents). Methodology was incompletely reported in most studies leading to lower confidence in the treatment estimates.Antithymocyte globulin (ATG) prevented acute graft rejection (17 studies: RR 0.63, 95% CI 0.51 to 0.78). The benefits of ATG on graft rejection were similar when used with (12 studies: RR 0.61, 0.49 to 0.76) or without (5 studies: RR 0.65, 0.43 to 0.98) calcineurin inhibitor (CNI) treatment. ATG (with CNI therapy) had uncertain effects on death (3 to 6 months, 3 studies: RR 0.41, 0.13 to 1.22; 1 to 2 years, 5 studies: RR 0.75, 0.27 to 2.06; 5 years, 2 studies: RR 0.94, 0.11 to 7.81) and graft loss (3 to 6 months, 4 studies: RR 0.60, 0.34 to 1.05; 1 to 2 years, 3 studies: RR 0.65, 0.36 to 1.19). The effect of ATG on death-censored graft loss was uncertain at 1 to 2 years and 5 years. In non-CNI studies, ATG had uncertain effects on death but reduced death-censored graft loss (6 studies: RR 0.55, 0.38 to 0.78). When CNI and older non-CNI studies were combined, a benefit was seen with ATG at 1 to 2 years for both all-cause graft loss (7 studies: RR 0.71, 0.53 to 0.95) and death-censored graft loss (8 studies: RR 0.55, 0.39 to 0.77) but not sustained longer term. ATG increased cytomegalovirus (CMV) infection (6 studies: RR 1.55, 1.24 to 1.95), leucopenia (4 studies: RR 3.86, 2.79 to 5.34) and thrombocytopenia (4 studies: RR 2.41, 1.61 to 3.61) but had uncertain effects on delayed graft function, malignancy, post-transplant lymphoproliferative disorder (PTLD), and new onset diabetes after transplantation (NODAT).Alemtuzumab was compared to ATG in six studies (446 patients) with early steroid withdrawal (ESW) or steroid minimisation. Alemtuzumab plus steroid minimisation reduced acute rejection compared to ATG at one year (4 studies: RR 0.57, 0.35 to 0.93). In the two studies with ESW only in the alemtuzumab arm, the effect of alemtuzumab on acute rejection at 1 year was uncertain compared to ATG (RR 1.27, 0.50 to 3.19). Alemtuzumab had uncertain effects on death (1 year, 2 studies: RR 0.39, 0.06 to 2.42; 2 to 3 years, 3 studies: RR 0.67, 95% CI 0.15 to 2.95), graft loss (1 year, 2 studies: RR 0.39, 0.13 to 1.30; 2 to 3 years, 3 studies: RR 0.98, 95% CI 0.47 to 2.06), and death-censored graft loss (1 year, 2 studies: RR 0.38, 0.08 to 1.81; 2 to 3 years, 3 studies: RR 2.45, 95% CI 0.67 to 8.97) compared to ATG. Creatinine clearance was lower with alemtuzumab plus ESW at 6 months (2 studies: MD -13.35 mL/min, -23.91 to -2.80) and 2 years (2 studies: MD -12.86 mL/min, -23.73 to -2.00) compared to ATG plus triple maintenance. Across all 6 studies, the effect of alemtuzumab versus ATG was uncertain on all-cause infection, CMV infection, BK virus infection, malignancy, and PTLD. The effect of alemtuzumab with steroid minimisation on NODAT was uncertain, compared to ATG with steroid maintenance.Alemtuzumab plus ESW compared with triple maintenance without induction therapy had uncertain effects on death and all-cause graft loss at 1 year, acute rejection at 6 months and 1 year. CMV infection was increased (2 studies: RR 2.28, 1.18 to 4.40). Treatment effects were uncertain for NODAT, thrombocytopenia, and malignancy or PTLD.Rituximab had uncertain effects on death, graft loss, acute rejection and all other adverse outcomes compared to placebo.

AUTHORS' CONCLUSIONS

ATG reduces acute rejection but has uncertain effects on death, graft survival, malignancy and NODAT, and increases CMV infection, thrombocytopenia and leucopenia. Given a 45% acute rejection risk without ATG induction, seven patients would need treatment to prevent one having rejection, while incurring an additional patient experiencing CMV disease for every 12 treated. Excluding non-CNI studies, the risk of rejection was 37% without induction with six patients needing treatment to prevent one having rejection.In the context of steroid minimisation, alemtuzumab prevents acute rejection at 1 year compared to ATG. Eleven patients would require treatment with alemtuzumab to prevent 1 having rejection, assuming a 21% rejection risk with ATG.Triple maintenance without induction therapy compared to alemtuzumab combined with ESW had similar rates of acute rejection but adverse effects including NODAT were poorly documented. Alemtuzumab plus steroid withdrawal would cause one additional patient experiencing CMV disease for every six patients treated compared to no induction and triple maintenance, in the absence of any clinical benefit. Overall, ATG and alemtuzumab decrease acute rejection at a cost of increased CMV disease while patient-centred outcomes (reduced death or lower toxicity) do not appear to be improved.

Hepatic Stellate Cells Directly Inhibit B Cells via Programmed Death-Ligand 1

We demonstrated previously that mouse hepatic stellate cells (HSCs) suppress T cells via programmed death-ligand 1 (PD-L1), but it remains unknown whether they exert any effects on B cells, the other component of the adaptive immune system. In this study, we found that mouse HSCs directly inhibited B cells and that PD-L1 was also integrally involved. We found that HSCs inhibited the upregulation of activation markers on activated B cells, as well as the proliferation of activated B cells and their cytokine/Ig production in vitro, and that pharmaceutically or genetically blocking the interaction of PD-L1 with programmed cell death protein 1 impaired the ability of HSCs to inhibit B cells. To test the newly discovered B cell-inhibitory activity of HSCs in vivo, we developed a protocol of intrasplenic artery injection to directly deliver HSCs into the spleen. We found that local delivery of wild-type HSCs into the spleens of mice that had been immunized with 4-hydroxy-3-nitrophenylacetyl-Ficoll, a T cell-independent Ag, significantly suppressed Ag-specific IgM and IgG production in vivo, whereas splenic artery delivery of PD-L1-deficient HSCs failed to do so. In conclusion, in addition to inhibiting T cells, mouse HSCs concurrently inhibit B cells via PD-L1. This direct B cell-inhibitory activity of HSCs should contribute to the mechanism by which HSCs maintain the liver's immune homeostasis.

Achieving incompatible transplantation through desensitization: current perspectives and future directions

The application of life-saving transplantation is severely limited by the shortage of organs, and histoincompatibility. To increase transplant rates in sensitized patients, new protocols for HLA and blood type incompatible (ABOi) desensitization have emerged. These approaches require significant desensitization using intravenous immunoglobulin, rituximab and plasma exchange. In addition, the development of donor-specific antibody responses post transplant is the major cause of allograft failure with return to dialysis. This increases patient morbidity/mortality and cost. Immunotherapeutic agents used for desensitization evolved from drug development in oncology and autoimmune diseases. Currently, there is a renaissance in development of novel drugs likely to improve antibody reduction in transplantation. These include agents that inactivate IgG molecules, anticytokine antibodies, costimulatory molecule blockade, anticomplement agents and therapies aimed at the plasma cell.

A systematic review of the use of rituximab as induction therapy in renal transplantation

Rituximab is a B-lymphocyte depleting agent used to treat lymphoma and autoimmune diseases. There has been recent interest in its use both for management of highly-sensitised and ABO-incompatible recipients but also for induction therapy before transplantation. This systematic review evaluates the evidence for its use as part of induction protocols in ABO-compatible, non-sensitised recipients. 4 databases and 3 trial registries were searched for studies of the use of rituximab as part of induction protocols. The small number of identified studies precluded meta-analysis and thus a narrative review was conducted. 12 manuscripts met the inclusion criteria, relating to 5 individual studies. No significant improvements in patient and graft survival or acute rejection rates were identified with rituximab induction. A single small study reported a trend towards improved graft function with the addition of rituximab induction to a standard immunosuppressive regimen. Rituximab was not found to be associated with increased infectious complications in any study but concerns were raised over possible associations with leukopaenia and cardiovascular mortality. Overall, no convincing benefit of rituximab induction was found and some safety concerns were identified. The results of on-going trials are awaited but further studies may be required before we can draw firm conclusions regarding the efficacy and safety of rituximab in this setting.