Marije C. Baas

Rituximab as induction therapy after renal transplantation: a randomized, double-blind, placebo-controlled study of efficacy and safety

We evaluated the efficacy and safety of rituximab as induction therapy in renal transplant patients. In a double‐blind, placebo‐controlled study, 280 adult renal transplant patients were randomized between a single dose of rituximab (375u2009mg/m2) or placebo during transplant surgery. Patients were stratified according to panel‐reactive antibody (PRA) value and rank number of transplantation. Maintenance immunosuppression consisted of tacrolimus, mycophenolate mofetil and steroids. The primary endpoint was the incidence of biopsy proven acute rejection (BPAR) within 6 months after transplantation. The incidence of BPAR was comparable between rituximab‐treated (23/138, 16.7%) and placebo‐treated patients (30/142, 21.2%, pu2009=u20090.25). Immunologically high‐risk patients (PRA >6% or re‐transplant) not receiving rituximab had a significantly higher incidence of rejection (13/34, 38.2%) compared to other treatment groups (rituximab‐treated immunologically high‐risk patients, and rituximab‐ or placebo‐treated immunologically low‐risk (PRAu2009≤u20096% or first transplant) patients (17.9%, 16.4% and 15.7%, pu2009=u20090.004). Neutropenia (<1.5u2009×u2009109/L) occurred more frequently in rituximab‐treated patients (24.3% vs. 2.2%, pu2009<u20090.001). After 24 months, the cumulative incidence of infections and malignancies was comparable. A single dose of rituximab as induction therapy did not reduce the overall incidence of BPAR, but might be beneficial in immunologically high‐risk patients. Treatment with rituximab was safe.

Treatment with everolimus is associated with a procoagulant state.

INTRODUCTIONnRenal transplant recipients are at increased risk of venous thromboembolic events, which is in part caused by their treatment with maintenance immunosuppressive drugs. Because we observed an increased incidence of venous thromboembolic events in renal transplant recipients treated with the mTOR inhibitor (mTORi) everolimus, we aimed to identify prothrombotic mechanisms of this immunosuppressive drug.nnnMATERIALS AND METHODSnIn a single center study, nested in a multi-center randomized controlled trial, we measured parameters of coagulation, anti-coagulation and fibrinolysis in renal transplant recipients, receiving the mTORi everolimus (n=16, mTOR group) and compared them to a similar patient group, receiving a calcineurin inhibitor and/or mycophenolate sodium (n=20, non-mTOR group). All patients were at least 6 months following transplantation with a stable transplant function.nnnRESULTSnThe use of an mTORi was associated with significantly higher levels of von Willebrand factor, prothrombin fragment 1+2, thrombin-activatable fibrinolysis inhibitor and plasminogen activator inhibitor-1 as compared to a non-mTORi based immunosuppressive regimen.nnnCONCLUSIONSnTreatment with an mTORi leads to increased endothelial activation, thrombin formation and impaired fibrinolysis in renal transplant recipients. This suggests an increased risk of thrombotic events in renal transplant recipients treated with mTOR inhibitors. A prospective study to establish the precise risk of thrombotic events in these patients is urgently needed.

Longitudinal Analysis of T and B Cell Phenotype and Function in Renal Transplant Recipients with or without Rituximab Induction Therapy

Background Prevention of rejection after renal transplantation requires treatment with immunosuppressive drugs. Data on their in vivo effects on T- and B-cell phenotype and function are limited. Methods In a randomized double-blind placebo-controlled study to prevent renal allograft rejection, patients were treated with tacrolimus, mycophenolate mofetil (MMF), steroids, and a single dose of rituximab or placebo during transplant surgery. In a subset of patients, we analyzed the number and phenotype of peripheral T and B cells by multiparameter flow cytometry before transplantation, and at 3, 6, 12, and 24 months after transplantation. Results In patients treated with tacrolimus/MMF/steroids the proportion of central memory CD4+ and CD8+ T cells was higher at 3 months post-transplant compared to pre-transplant levels. In addition, the ratio between the percentage of central memory CD4+ and CD4+ regulatory T cells was significantly higher up to 24 months post-transplant compared to pre-transplant levels. Interestingly, treatment with tacrolimus/MMF/steroids resulted in a shift toward a more memory-like B-cell phenotype post-transplant. Addition of a single dose of rituximab resulted in a long-lasting B-cell depletion. At 12 months post-transplant, the small fraction of repopulated B cells consisted of a high percentage of transitional B cells. Rituximab treatment had no effect on the T-cell phenotype and function post-transplant. Conclusions Renal transplant recipients treated with tacrolimus/MMF/steroids show an altered memory T and B-cell compartment post-transplant. Additional B-cell depletion by rituximab leads to a relative increase of transitional and memory-like B cells, without affecting T-cell phenotype and function. Trial Registration ClinicalTrials.gov NCT00565331

Interstitial pneumonitis caused by everolimus: a case–cohort study in renal transplant recipients

The use of inhibitors of the mammalian target of rapamycin (mTORi) in renal transplantation is associated with many side effects, the potentially most severe being interstitial pneumonitis. Several papers have reported on sirolimus‐induced pneumonitis, but less is published on everolimus‐induced pneumonitis (EIP). Data on risk factors for contracting EIP are even more scarce. In the present case–cohort study in renal transplant recipients (RTR), we aimed to assess the incidence and risk factors of EIP after renal transplantation. This study is a retrospective substudy of a multicenter randomized controlled trial. All patients included in the original trial and treated with prednisolone/everolimus were included in this substudy. RTR who developed EIP were identified as cases. RTR without pulmonary symptoms served as controls. Thirteen of 102 patients (12.7%) developed EIP. We did not find any predisposing factors, especially no correlation with everolimus concentration. On pulmonary CT scan, EIP presented with an organizing pneumonia‐like pattern, a nonspecific interstitial pneumonitis‐like pattern, or both. Median time (range) to the development of EIP after start of everolimus was 162 (38–407) days. In conclusion, EIP is common in RTR, presenting with an organizing pneumonia, a nonspecific interstitial pneumonitis‐like pattern, or both. No predisposing factors could be identified (Trial registration number: NTR567 (www.trialregister.nl), ISRCTN69188731).

The DESCARTES-Nantes survey of kidney transplant recipients displaying clinical operational tolerance identifies 35 new tolerant patients and 34 almost tolerant patients

BACKGROUNDnKidney recipients maintaining a prolonged allograft survival in the absence of immunosuppressive drugs and without evidence of rejection are supposed to be exceptional. The ERA-EDTA-DESCARTES working group together with Nantes University launched a European-wide survey to identify new patients, describe them and estimate their frequency for the first time.nnnMETHODSnSeventeen coordinators distributed a questionnaire in 256 transplant centres and 28 countries in order to report as many operationally tolerant patients (TOL; defined as having a serum creatinine <1.7 mg/dL and proteinuria <1 g/day or g/g creatinine despite at least 1 year without any immunosuppressive drug) and almost tolerant patients (minimally immunosuppressed patients (MIS) receiving low-dose steroids) as possible. We reported their number and the total number of kidney transplants performed at each centre to calculate their frequency.nnnRESULTSnOne hundred and forty-seven questionnaires were returned and we identified 66 TOL (61 with complete data) and 34 MIS patients. Of the 61 TOL patients, 26 were previously described by the Nantes group and 35 new patients are presented here. Most of them were noncompliant patients. At data collection, 31/35 patients were alive and 22/31 still operationally tolerant. For the remaining 9/31, 2 were restarted on immunosuppressive drugs and 7 had rising creatinine of whom 3 resumed dialysis. Considering all patients, 10-year death-censored graft survival post-immunosuppression weaning reached 85% in TOL patients and 100% in MIS patients. With 218 913 kidney recipients surveyed, cumulative incidences of operational tolerance and almost tolerance were estimated at 3 and 1.5 per 10 000 kidney recipients, respectively.nnnCONCLUSIONSnIn kidney transplantation, operational tolerance and almost tolerance are infrequent findings associated with excellent long-term death-censored graft survival.

Differential effects of donor-specific HLA antibodies in living- versus deceased-donor transplantation.

The presence of donor‐specific anti‐HLA antibodies (DSAs) is associated with increased risk of graft failure after kidney transplant. We hypothesized that DSAs against HLA class I, class II, or both classes indicate a different risk for graft loss between deceased and living donor transplant. In this study, we investigated the impact of pretransplant DSAs, by using single antigen bead assays, on long‐term graft survival in 3237 deceased and 1487 living donor kidney transplants with a negative complement‐dependent crossmatch. In living donor transplants, we found a limited effect on graft survival of DSAs against class I or II antigens after transplant. Class I and II DSAs combined resulted in decreased 10‐year graft survival (84% to 75%). In contrast, after deceased donor transplant, patients with class I or class II DSAs had a 10‐year graft survival of 59% and 60%, respectively, both significantly lower than the survival for patients without DSAs (76%). The combination of class I and II DSAs resulted in a 10‐year survival of 54% in deceased donor transplants. In conclusion, class I and II DSAs are a clear risk factor for graft loss in deceased donor transplants, while in living donor transplants, class I and II DSAs seem to be associated with an increased risk for graft failure, but this could not be assessed due to their low prevalence.

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

Traditionally, antirejection therapy in organ transplantation has mainly been directed at T cells. During recent years, the role of B cells in acute rejection has attracted more attention. In the Radboud University Medical Center (Nijmegen, The Netherlands) we performed a randomized, placebo controlled study to assess the efficacy and safety of rituximab as induction therapy after renal transplantation. In parallel we investigated the effects of rituximab on the numbers and function of B and T cells. An overview of the results, which have largely been published in peer reviewed papers, is presented below.

Cyclosporine versus everolimus : effects on the glomerulus

Inhibitors of the mammalian target of rapamycin (mTOR) have been associated with proteinuria. We studied the development of proteinuria in renal transplant recipients (RTR) treated with the mTOR inhibitor everolimus in comparison with a calcineurin inhibitor. We related the presence of proteinuria to histopathological glomerular findings in two‐yr protocol biopsies. In a single‐center study, nested in a multicenter randomized controlled trial, we determined eGFR, proteinuria, and renal biopsy data (light‐ and electron microscopy) of RTR receiving prednisolone/everolimus (P/EVL) (n = 16) in comparison with patients treated with prednisolone/cyclosporine A (P/CsA) (n = 7). All patients had been on the above‐described maintenance immunosuppression for 18 months. Renal function at two yr after transplantation did not differ between patients receiving P/EVL or P/CsA (eGFR 45.5 vs. 45.7 mL/min/1.73 m2). Proteinuria was slightly increased in P/EVL vs. P/CsA group (0.29 vs. 0.14 g/24 h, p = 0.06). There were no differences in light‐ or electron microscopic findings. We could not demonstrate increased podocyte effacement or changes in glomerular basement membrane (GBM) thickness in P/EVL‐treated patients. In conclusion, long‐term treatment with everolimus leaves the GBM and podocytes unaffected.

Peri- and Postoperative Treatment with the Interleukin-1 Receptor Antagonist Anakinra Is Safe in Patients Undergoing Renal Transplantation: Case Series and Review of the Literature

In patients undergoing solid organ transplantation, the presence of an interleukin-1 (IL-1) driven disease may require the addition of IL-1 inhibiting drugs to the standard immunosuppressive regimen to protect against inflammation and negative graft outcome. Three patients undergoing renal transplantation were treated perioperatively with the interleukin-1 receptor antagonist anakinra. Kidney function increased rapidly in all three and the only complications seen were minor infections. In vitro studies report associations between serum and urinary levels of IL-1β and IL-1 receptor antagonist and negative graft outcome, and studies in animals and two small human trials illustrate a possible protective effect of anti-IL-1 therapy after solid organ transplantation. Peri- and postoperative use of anakinra is safe and effective in patients undergoing renal transplantation.

Cytokine Release After Treatment With Rituximab in Renal Transplant Recipients

Background Treatment with rituximab may be accompanied by a systemic cytokine release. We studied the effects of a single dose of rituximab on cytokine levels in transplant patients and examined the underlying mechanism. Methods Twenty renal transplant recipients (10 rituximab-treated, 10 placebo-treated) were recruited from a randomized clinical trial. Rituximab or placebo was infused during surgery, and blood samples were taken before, during, and after surgery and analyzed for interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12, IL-17, interferon-&ggr;, macrophage inflammatory protein (MIP)-1&bgr;, transforming growth factor-&bgr;, and tumor necrosis factor-&agr;. in vitro, healthy donor peripheral blood mononuclear cells, purified B cells, monocytes, natural killer (NK) cells, or combinations thereof were incubated with rituximab, rituximab-F(ab′)2, or medium and MIP-1&bgr;, IL-10, interferon-&ggr;, and tumor necrosis factor-&agr; levels were measured in the supernatant. Results Rituximab-treated patients had higher serum levels of IL-10 (101 ± 35 pg/mL vs 41 ± 9 pg/mL; P < 0.01) and MIP-1&bgr; (950 ± 418 pg/mL vs 125 ± 32 pg/mL; P < 0.001) compared to placebo-treated patients at 2 hours after start of infusion. There was no difference in the level of other cytokines. In vitro, the addition of rituximab, but not rituximab-F(ab′)2 fragments, only led to significantly increased levels of MIP-1&bgr; in co-cultures of B and NK cells. Levels of MIP-1&bgr; were higher in patients with a high affinity Fc-receptor compared to those with a lower affinity Fc&ggr;RIIIa (1356 ± 184 pg/mL vs 679 ± 273 pg/mL; P < 0.01). Conclusions In addition to B-cell depletion, rituximab can modulate the immune response by inducing cytokine secretion, especially IL-10 and MIP-1&bgr;. Rituximab-induced MIP-1&bgr; secretion depends on the combined presence of B cells and FcR-bearing cells, especially NK cells.