Antilymphoid antibody preconditioning and tacrolimus monotherapy for pediatric kidney transplantation

Steroid avoidance/withdrawal and maintenance immunosuppression in pediatric kidney transplantation

BACKGROUND

Corticosteroids have been an integral part of maintenance immunosuppression for pediatric kidney transplantation. However, prolonged steroid therapy is associated with significant toxicities resulting in several SW/avoidance strategies in recent years.

METHOD/OBJECTIVE

This comprehensive review aims to discuss steroid-related toxicities and the safety, efficacy, and benefit of steroid avoidance/withdrawal immunosuppression in pediatric kidney transplant recipients.

RESULTS

Initial studies of SW/avoidance conducted in the setting of CSA and AZA showed an increased incidence of AR but no increase in graft loss or mortality with SW/avoidance maintenance immunosuppression. Studies performed under modern immunosuppression (induction therapy, Tac, and MMF) show no significant increase in AR or graft loss with SW/avoidance immunosuppression. Furthermore, SW/avoidance immunosuppression is associated with significant improvement in growth, BMI, BP control, and lipid profile in pediatric kidney transplant recipients. Despite these data, SW/avoidance remains controversial, and only 40% of pediatric kidney transplant recipients in the United States are currently on SW/avoidance maintenance immunosuppression.

CONCLUSION

SW/avoidance maintenance immunosuppression is safe and associated with fewer side effects compared with steroid-inclusive maintenance immunosuppression in pediatric kidney transplant recipients.

Immunosuppressants in Organ Transplantation

The goal of immunosuppressive therapy post-transplantation in pediatric renal transplant recipients is to prevent acute and chronic rejection while minimizing drug side effects. Most therapies alter immune response mechanisms but are not immunologically specific, and a careful balance is required to find the dose that prevents rejection of the graft while minimizing the risks of overimmunosuppression leading to infection and cancer. While this chapter because of space constraints focuses on immunosuppressive therapy in pediatric renal transplant recipients, many aspects can be applied on pediatric recipients of other solid organ transplants such as the liver and heart. The major maintenance immunosuppressive agents currently used in various combination regimens are tacrolimus, cyclosporine, mycophenolate mofetil, azathioprine, everolimus, sirolimus, and glucocorticoids (steroids). Although data from adult renal transplantation trials are used to help guide management decisions in pediatric patients, immunosuppressive therapy in pediatric renal transplant recipients often must be modified because of the unique dosage requirements and clinical effects of these agents in children, including their impact on growth and development. The optimal immunosuppressive therapy post-transplant is not established. The goal remains to find the best combination of immunosuppressive agents that optimizes allograft survival by preventing acute rejection while limiting drug toxicities.

Eight-year follow-up in pediatric living donor kidney recipients receiving alemtuzumab induction

Recipient lymphocytes are crucial for direct and indirect pathways of allorecognition. We proposed that the administration of alemtuzumab several weeks pretransplantation could eradicate peripheral lymphatic cells and promote donor-specific acceptance. This was a single-center, retrospective review of 101 consecutive living donor kidney transplantations in pediatric patients (age 7 months-18 years), performed between September 2006 and April 2010. IS protocol included two 30 mg doses of alemtuzumab: The first was given 12-29 days prior to transplantation, and the second at the time of transplantation. Maintenance IS was based on combination of low-dose CNI and mycophenolate, with steroids tapered over the first 5 days post-transplantation. Patients were followed for 7.8±1.3 years, and protocol biopsies were taken 1 month, 1, 3, and 5 years post-transplant. The Kaplan-Meier 8-year patient and graft survival rates in the cyclosporine-treated patients were 82.0±7.3% and 71.6±7.3, and in the tacrolimus-treated patients were 97.2±5.4 and 83.8±6.0%. Biopsy-proven acute rejection developed in 35% of cyclosporine-treated patients and in 8% of tacrolimus-treated patients. Alemtuzumab pretreatment prior to LRD kidney transplantation, followed by maintenance immunosuppression with tacrolimus and MMF, is associated with reasonable long-term results in pediatric patients.

Biologics in renal transplantation

The biologics used in transplantation clinical practice include several monoclonal and polyclonal antibodies aimed at specific cellular receptors. The effect of their mechanisms of action includes depleting or blocking specific cell subpopulations, complement system, or removing circulating preformed antibodies and blocking their production. They are used in induction, desensitization ABO-incompatible renal transplantation, rescue therapy of steroid-resistant acute rejection, treatment of posttransplant recurrence of primary disease such as nephrotic syndrome or atypical hemolytic-uremic syndrome, and in late humoral rejection. There are various indications for the use of biologic agents before and early or late after renal transplantation in both high- and low-risk recipients. In the latter situation, the biologics-based induction is used to further minimize immunosuppression maintenance. The targets of several biologic agents are present across a variety of cells, and manipulation of the immune system with biologics may be associated with significant risk of acute and late-onset adverse events; therefore, clinical risk-versus-benefit ratio must be carefully balanced in every case. Several trials on novel biologics are reported in adults but not in the pediatric population.

Alemtuzumab induction with tacrolimus monotherapy in 25 pediatric renal transplant recipients

ALA induction in transplantation has been shown to reduce the need for maintenance immunosuppression. We report the outcome of 25 pediatric renal transplants between 2007 and 2010 using ALA induction followed by tacrolimus maintenance monotherapy. Patient ages were 1-19 yr (mean 14 ± 4.1 yr). Time of follow-up was 7-51 months (mean 26 ± 13 months). Tacrolimus monotherapy was maintained in 48% of patients, and glucocorticoids were avoided in 80% of recipients. Mean plasma creatinine and GFR at one yr post-transplant were 0.88 ± 0.3 mg/dL and 104.4 ± 25 mL/min/1.73m(2) , respectively. One, two, and three-yr actuarial patient and graft survival rates were 100%. The incidence of early AR (<12 months after transplantation) was 12%, while the incidence of late AR (after 12 months) was 16%. Forty-four percent of the recipients recovered normal, baseline renal function after an episode of AR, and 44% had persistent renal dysfunction (plasma creatinine 1.0-1.8 mg/dL). One graft was lost four yr after transplantation due to medication non-compliance. Four (16%) patients developed BK or CMV infection. In our experience, ALA induction with tacrolimus monotherapy resulted in excellent short- and mid-term patient and graft survival in low-immunologic risk pediatric renal transplant recipients.

Steroid withdrawal in renal transplantation

Over the last decade, steroid minimization became one of the major goals in pediatric renal transplantation. Different protocols have been used by individual centers and multicenter study groups, including early and late steroid withdrawal or even complete avoidance. The timing of steroid withdrawal determines if antibodies are used, as avoidance and early withdrawal require antibody induction, while late withdrawal typically does not. A monoclonal antibody was used in most protocols during an early steroid withdrawal together with tacrolimus and mycophenolate mofetil in low immunological risk patients. Polyclonal induction was reported as effective in high-risk patients. Cyclosporine A and mycophenolate mofetil were used in late steroid withdrawal with no induction. All described protocols were effective in terms of preventing acute rejection and preserving renal graft function. There was no superiority of any specific protocol in terms of clinical benefits of steroid withdrawal. Pre-puberty determined growth benefit while other clinical advantages, including better control of glycemia, lipids, and blood pressure, were age independent. It is not clear whether the steroid withdrawal increases the risk of recurrence of primary glomerular diseases post-transplant, however it cannot be excluded. There is no evidence to date for a higher risk of anti-HLA production in steroid-free children after renal transplantation. Key summary points--Current strategies to minimize the steroid-related adverse effects in pediatric renal graft recipients include steroid withdrawal, early or late after transplantation, or complete steroid avoidance--Early steroid withdrawal or avoidance is generally used following the induction therapy with mono- or polyclonal antibodies, while in late steroid withdrawal induction therapy was generally not used- Elimination of steroids (early or late) does not increase the risk of acute rejection and does not deteriorate long-term renal graft function- Early steroid withdrawal is possible in patients at high immunological risk using a combination of polyclonal antibody induction, tacrolimus, and mycophenolate mofetil- All protocols of steroid minimization showed relevant clinical benefits, however the growth-related benefit was limited to pre-pubertal patients in all but one of the studies- Adverse events of steroid withdrawal occurred in a higher incidence of post-transplant bone marrow suppression Key research points - There is no clear evidence of the impact of steroid withdrawal on the risk of recurrence of primary glomerulonephritis after renal transplantation in children, therefore further evaluation of this important issue should be performed in prospective trials- There is limited pediatric data on the risk of anti-HLA/donor-specific antibody production in steroid-free patients after renal transplantation. It is not clear whether the selection of the type of induction antibody (lymphocyte depleting versus short, two-dose administration of anti-IL2R inhibitor) is important in this term. The production of anti-HLA antibodies should then be monitored on a regular basis and analyzed in prospective trials.

The effects of preoperative immunosuppressive therapy on ischemia and reperfusion (I/R) injury in healthy rats

PURPOSE

Warm-ischemia-induced injuries might be encountered during renal transplants from cadavers and healthy donors. Toll-like receptors (TLR) in ischemia-reperfusion (I/R) injury are one of the indicators of intracellular injury pathways. The intensity of ischemic injury is directly proportionate to high TLR levels. To minimize the I/R injury, we investigated TLR2 and TLR4 levels on rats, which were pretreated with tacrolimus (FK506) before I/R.

METHODS

Eight Wistar albino rats in the study group were administered .01 mg/kg intramuscular tacrolimus. Administration to the study group was performed 24 and 1 h before warm ischemia. Eight rats in the control group were injected with 0.1 c.c. of distilled water. Blood samples were collected from the tail veins of all the rats on the first, second and third days. Expression levels of TLR2 and TLR4 genes were analyzed using the polymerase chain reaction method, to determine any significant difference between the control and study groups on the days when blood was taken.

RESULTS

TLR2 (p = 0.045) and TLR4 (p = 0.022) levels in the study group were found to be statistically, and significantly, lower than those in the control group, on the second day following warm-ischemia- and reperfusion-induced injury.

CONCLUSIONS

Administration of immunosuppressive drugs to healthy donor rats led to a statistically significant reduction in the expression levels of TLR2 and TLR4 in the early period. In light of the data obtained by this study, we hypothesize that a preoperative therapy on donors might have a role in preventing I/R injury.

Alemtuzumab induction in pediatric kidney transplantation

Recipient parenchymal lymphatic cells are crucial for direct and indirect pathways of allorecognition. We proposed that alemtuzumab, being infused several weeks pretransplant could eradicate peripheral lymphatic cells and promote donor-specific tolerance. We present here a single center, retrospective review of 101 consecutive living-donor kidney transplantations to pediatric patients aged from seven month to 18 yr, performed between September 2006 and April 2010. Immunosupression protocol included two 30 mg doses of alemtuzumab: first given 12-29 d prior to transplantation and second at the time of transplantation. Maintenance immunosupression was based on combination of low dose and wide range CNI and mycophenolate. Patients were followed for 3.8 ± 1.4 yr and protocol biopsies were taken one month, one, and three yr post transplant. The Kaplan-Meier graft and patient survival was 96% and 97% for one yr, 89% and 93% for three yr. Biopsy proven acute rejection developed in 26% patients at one yr and in 35% at two yr, no rejections occurred beyond two yr. We conclude that alemtuzumab pretreatment prior to living related donor kidney transplantation allows to reach satisfactory middle-term results in pediatric patients with wide range and low CNI concentrations.

Steroid avoidance in renal transplantation

PURPOSE OF REVIEW

The recent surge in the use of steroid-avoidance protocols for pediatric renal transplant recipients has been fueled by the numerous adverse side effects of steroids and development of alternatives for successful immunosuppression. Steroid-avoidance protocols were first attempted in the adult population, and with positive outcomes, pediatrics soon followed. As more pediatric patients are placed on steroid-avoidance protocols, we must begin answering several important questions such as patient and graft outcome, safety profiles of various steroid-avoidance induction protocols, viral complications and incidence of transplant lymphoproliferative disease (PTLD), metabolic benefits, and the affect of steroid minimization on growth.

RECENT FINDINGS

Initial results from steroid-avoidance protocols show these protocols are safe and effective with improved graft survival, metabolic profiles, and linear growth without an increase in viremia or PTLD.

SUMMARY

Although initial results are promising, there is still a lack of long-term data from large, prospective randomized trials, and there is not enough data to determine the optimal steroid-avoidance protocol for pediatric renal transplant recipients.

Steroid minimization in pediatric renal transplantation: Early withdrawal or avoidance?

  Clinically important adverse events associated with the use of corticosteroids post-transplantation include hypertension, dyslipidemia, impaired glucose metabolism (including diabetes mellitus), growth retardation, bone fractures, and cosmetic problems. Over recent years, a number of studies have investigated the effect of minimizing exposure to corticosteroids in post-transplant immunosuppression protocols in both adults and children. In pediatric patients, several different approaches have been evaluated, including late steroid withdrawal, early steroid withdrawal, and complete steroid avoidance with or without poly- or monoclonal antibody induction and a variety of maintenance immunosuppressants. This manuscript reviews the key studies and documents the specific clinical benefits associated with steroid minimization. The development of PTLD and bone marrow suppression has been a major safety concern in some of these studies. These studies and other adverse effects are discussed.

Induction therapy: why, when, and which agent?

The long-term outcome of paediatric transplantation has improved over the last decade with an increase in the armamentarium of immunosuppressive agents. However, the battle against the hostile immune response at the time of and after transplantation continues. Induction therapy can reduce early injury, to optimize the long-term allograft survival. The goal of induction immunosuppression in paediatric transplantation is to permit the use of lower doses of maintenance immunosuppressive agents without increased rates of acute allograft rejection and chronic allograft damage. The aim of this review is to summarize the current literature relating to the use of antibody agents for induction in paediatric solid organ transplantation.

Prolonged survival of composite facial allografts in non-human primates associated with posttransplant lymphoproliferative disorder

BACKGROUND

Composite tissue allotransplantation may have different immunosuppressive requirements and manifest different complications compared with solid organ transplantation. We developed a non-human primate facial composite tissue allotransplantation model to investigate strategies to achieve prolonged graft survival and immunologic responses unique to these allografts.

METHODS

Composite facial subunits consisting of skin, muscle, and bone were heterotopically transplanted to mixed lymphocyte reaction-mismatched Cynomolgus macaques. Tacrolimus monotherapy was administered via continuous intravenous infusion for 28 days then tapered to daily intramuscular doses.

RESULTS

Five of the six animals treated with tacrolimus monotherapy demonstrated rejection-free graft survival up to 177 days (mean, 113 days). All animals with prolonged graft survival developed posttransplant lymphoproliferative disorders (PTLD). Three animals converted to rapamycin after 28 days of rejection of their allografts, but did not develop PTLD. Genotypic analysis of PTLD tumors demonstrated donor origin in three of the five analyzed by short-tandem repeats. Sustained alloantibodies were detected in rejecting grafts and absent in nonrejecting grafts.

CONCLUSIONS

Tacrolimus monotherapy provided prolonged rejection-free survival of composite facial allografts in a non-human primate model but was associated with the development of a high frequency of donor-derived PTLD tumors. The transplantation of a large volume of vascularized bone marrow in composite tissue allografts may be a risk factor for PTLD development.

Kidney after nonrenal transplantation-the impact of alemtuzumab induction

BACKGROUND

Calcineurin inhibitor nephrotoxicity in nonrenal allograft recipients can lead to end-stage renal disease and the need for kidney transplantation. We sought to evaluate the role of alemtuzumab induction in this population.

PATIENTS AND METHODS

We evaluated 144 patients undergoing kidney transplantation after nonrenal transplantation between May 18, 1998, and October 8, 2007. Seventy-two patients transplanted between January 15, 2003, and October 8, 2007, received alemtuzumab induction and continued their pretransplant immunosuppression. Seventy-two patients transplanted between May 18, 1998, and July 21, 2007, did not receive alemtuzumab induction, but received additional steroids and maintenance immunosuppression. Donor and recipient demographics were comparable.

RESULTS

Overall, 1- and 3-year patient survival and renal function were comparable between the two groups. One- and 3-year graft survival was 93.0% and 75.3% in the alemtuzumab group and 83.3% and 68.7% in the no alemtuzumab group, respectively (P=0.051). The incidence of acute rejection was lower in the alemtuzumab group, 15.3%, than in the no alemtuzumab group, 41.7% (P=0.0001). The incidence of delayed graft function was lower in the alemtuzumab group, 9.7%, than in the no alemtuzumab group, 25.0% (P=0.003). The incidence of viral complications was comparable.

CONCLUSION

Alemtuzumab induction with simple resumption of baseline immunosuppression in patients undergoing kidney transplantation after nonrenal transplantation represents a reasonable immunosuppressive strategy.

Pediatric kidney transplantation using a novel protocol of rapid (6-day) discontinuation of prednisone: 2-year results

BACKGROUND

There are few prospective studies of prednisone-free immunosuppression (IS) in pediatric kidney transplant (KTx) recipients. We studied the outcomes of a protocol using rapid discontinuation of prednisone (RDP, <1 week) and thymoglobulin induction.

METHODS

Twenty-one RDP recipients (mean age 14+/-3 years) received KTx between May 2002 and December 2005 and were matched with controls (n=39) for age, race, and donor source. For the RDP group, IS consisted of prednisone tapered off over 6 days, thymoglobulin, mycophenolate mofetil, and cyclosporine A (CsA). In controls, IS consisted of thymoglobulin, maintenance prednisone, azathioprine, and CsA.

RESULTS

For the RDP group, graft survival at 1 and 2 years was 90% and 86%; for the controls, graft survival at 1 and 2 years was 92%, and 90% (P=0.86). For the RDP group, the incidence of acute rejection at 1 and 2 years was 14% and 19%; for controls, the incidence of acute rejection at 1 and 2 years was 23%, and 31% (P=0.17). Of the 18 RDP recipients with functioning grafts, 89% remain prednisone-free at follow-up. There was no significant difference between groups in recipient survival rates, incidence of hypertension, chronic allograft nephropathy, or cytomegalovirus disease.

CONCLUSIONS

RDP using thymoglobulin, mycophenolate mofetil, and CsA in selected pediatric KTx recipients is associated with recipient and graft survival rates and acute rejection incidence comparable with quadruple drug therapy.

Alemtuzumab induction in kidney transplantation: clinical results and impact on T-regulatory cells

Alemtuzumab (ALT), a humanized monoclonal anti-CD52 antibody, was introduced in solid organ transplantation as an induction agent. ALT associated with anticalcineurins has provided a low incidence of acute rejection episodes (ARE) and potential tolerogenic properties. We analyzed the clinical outcomes and effects on peripheral Treg of renal transplant recipients treated with ALT. Six-month data on kidney alone or kidney combined with pancreas or liver patients treated with ALT and tacrolimus (TAC) in standard doses were compared with those on renal transplant recipients of similar demography who were not treated with ALT. We evaluated patient and graft survivals, ARE incidence, hematological parameters, renal function, adverse events, and CD4+CD25+FoxP3+ T cells in peripheral blood. Demographics of recipients, donors, and transplants were similar in both groups. Mean HLA mismatch was slightly greater among ALT-treated patients (3.5 vs 2.5). No combined transplantation was performed in the ALT-untreated group. Patient and graft survivals were 100% without rejection or serious infections in both groups. ALT-treated recipients showed anemia and leukopenia in 3 patients as well as severe lymphopenia in 5 recipients, who partially recovered on day 90. Final mean plasma creatinine was 1.4 mg/dL, while calculated creatinine clearance was approximately 65 mL/min in both groups. Mean Treg cell percentage was higher among ALT-treated recipients than the comparative group or healthy controls (P < .05). In conclusion, renal transplantation results obtained using ALT with rigorous immunosuppressive therapy were excellent; serious adverse events and acute rejection were absent. The effect of the increased proportion of Treg cells must be evaluated with longer observation.

Two hundred living donor kidney transplantations under alemtuzumab induction and tacrolimus monotherapy: 3-year follow-up

Alemtuzumab has been used in off-label studies of solid organ transplantation. We extend our report of the first 200 consecutive living donor solitary kidney transplantations under alemtuzumab pretreatment with tacrolimus monotherapy and subsequent spaced weaning to 3 years of follow-up. We focused especially on the causes of recipient death and graft loss, and the characteristics of rejection. The actuarial 1-, 2- and 3-year patient and graft survivals were 99.0% and 98.0%, 96.4% and 90.8% and 93.3% and 86.3%, respectively. The cumulative incidence of acute cellular rejection (ACR) at the following months was 2%</=6, 9.0%</=12, 16.5%</=18, 19.5%</=24, 23.5%</=30, 24.0%</=36 and 25%</=42. The mean serum creatinine (mg/dL) and glomerular filtration rate (mL/min/1.73 m(2)) at 1 and 3 years were 1.4 +/- 0.6 and 58.7 +/- 21.6 and 1.5 +/- 0.7 and 54.9 +/- 20.9, respectively. Fifty (25%) recipients had a total of 89 episodes of ACR. About 88.7% of ACR episodes were Banff 1, and of those, 82% were steroid-sensitive. Nine (4.5%) recipients had antibody-mediated rejection (AMR). About 76.5% were weaned but only 46% are currently on spaced dose (qod or less) tacrolimus monotherapy, and 94.4% remained steroid-free from the time of transplantation. Infectious complications were uncommon. This experience suggests the 3-year efficacy of this approach.

Post-transplant lymphoproliferative disease

Post-transplant lymphoproliferative disease (PTLD) emerged in the mid-1990s as a major graft- and life-threatening complication of pediatric kidney transplantation. This condition, usually involving uncontrolled B lymphocyte proliferation, straddles the border between infection and malignancy, since Epstein-Barr virus (EBV) is intimately associated with the pathogenesis. PTLD is seen more in younger children (more likely to be EBV seronegative), Caucasian race, and in association with the more potent immunosuppression drugs. The clinical presentation typically involves multiple enlarged lymph nodes but varies based on localization of the lymphadenopathy. The diagnosis is based primarily on histopathological features. Treatment strategies include reduction of immunosuppression, use of anti-B cell antibodies, infusion of EBV-specific cytotoxic T lymphocytes, and chemotherapy. Many different strategies have been tried to prevent PTLD, ranging from serial EBV viral load monitoring and pre-emptive immunosuppression reduction to anti-viral prophylaxis. None of the major treatment or prevention strategies has been subject to randomized clinical trials, so their relative efficacy is still unknown. PTLD remains a risk factor for graft loss, though re-transplants have not, to date, been associated with repeat PTLD.

Calcineurin inhibitor sparing in paediatric solid organ transplantation : managing the efficacy/toxicity conundrum

Despite their efficacy, the calcineurin inhibitors (CNIs) ciclosporin and tacrolimus carry a risk of debilitating adverse effects, especially nephrotoxicity, that affect the long-term outcome and survival of children who are given organ transplants. Simple reduction in dosage of CNI has little or no long-term benefit on their adverse effects, and complete withdrawal without threatening graft outcome may only be possible after liver transplantation. Until the last decade, the only option was to increase corticosteroid and/or azathioprine doses, which imposed additional long-term hazards. Considered here are the emerging generation of new agents offering an opportunity for improving long-term graft survival, minimizing CNI-related adverse events and ensuring patient well-being.A holistic, multifaceted strategy may need to be considered - initial selection and optimized use and monitoring of immunosuppressant regimens, early recognition of indicators of patient and graft dysfunction, and, where applicable, early introduction of CNI-sparing regimens facilitating CNI withdrawal. The evidence reviewed here supports these approaches but remains far from definitive in paediatric solid organ transplantation. Because de novo immunosuppression uses CNI in more than 93% of patients, reduction of CNI-related adverse effects has focused on CNI sparing or withdrawal.A recurring theme where sirolimus and mycophenolate mofetil have been used for this purpose is the importance of their early introduction to limit CNI damage and provide long-term benefit: for example, long-term renal function critically reflects that at 1 year post-transplant. While mycophenolic acid shows advantages over sirolimus in preserving renal function because the latter is associated with proteinuria, sirolimus appears the more potent immunosuppressant but also impairs early wound healing. The use of CNI-free immunosuppressant regimens with depleting or non-depleting antibodies plus sirolimus and mycophenolic acid needs much wider investigation to achieve acceptable rejection rates and conserve renal function. The adverse effects of the alternative immunosuppressants, particularly the dyslipidaemia associated with sirolimus, needs to be minimized to avoid replacing one set of adverse effects (from CNIs) with another. While we can only conjecture that judicious combinations with the second generation of novel immunosuppressants currently in development will provide these solutions, a rationale of low-dose therapy with multiple immunosuppressants acting by complementary mechanisms seems to hold the promise for efficacy with minimal toxicity until the vision of tolerance achieves reality.

Refractory hypercalcemia in an infant secondary to talc pleurodesis resolving after renal transplantation

Talc pleurodesis is the definitive therapy of recurrent pneumothorax and has not been associated with metabolic complications. We report an anephric male infant who developed severe hypercalcemia 6 months following talc pleurodesis for recurrent peritoneal dialysis-related hydrothorax. The etiology of hypercalcemia was related to persistently elevated 1,25-dihydroxyvitamin D(3) (1,25[OH]2D) levels. The source appeared to be the extrarenal production of 1,25(OH)2D from macrophages in a large thoracic talc granuloma. Hypercalcemia was controlled with a combination of a low calcium diet, low calcium dialysis, ketoconazole and hydroxychloroquine, but elevated 1,25(OH)2D levels persisted. At 32 months of age the child underwent renal transplantation with alemtuzumab pre-conditioning. The hypercalcemia resolved immediately, with normalization of serum 1,25(OH)2D levels and without hypercalciuria. This case demonstrates that hypercalcemia is a potential complication of talc pleurodesis from the extrarenal production of 1,25(OH)2D and that alemtuzumab, a monoclonal antibody directed against the CD52 antigen (which is expressed on almost all macrophages), may have a role in the treatment of hypercalcemia associated with granulomatous conditions.

Alemtuzumab preconditioning with tacrolimus monotherapy-the impact of serial monitoring for donor-specific antibody

BACKGROUND

Antibody preconditioning with tacrolimus monotherapy has allowed many renal allograft recipients to be maintained on spaced weaning.

METHODS

Of 279 renal allograft recipients transplanted between March 2003 and December 2004, 222 (80%) had spaced weaning (i.e., reduction of tacrolimus monotherapy dosing to every other day, three times a week, twice a week, or once a week) attempted. Routine monitoring for donor-specific antibody (DSA) was begun in September 2004. Mean follow-up is 34+/-6.5 months after transplantation and 26+/-8.1 months after the initiation of spaced weaning.

RESULTS

One hundred and twenty-two (44%) patients remained on spaced weaning. One- and 2-year actual patient/graft survival was 99%/99%, and 97%/96%. Fifty-six (20%) patients experienced acute rejection after initiation of spaced weaning. One- and 2-year actual patient/graft survival was 100%/98%, and 94%/78%. Forty-two (15%) patients with stable renal function had spaced weaning stopped because of the development of DSA, which disappeared in 17 (40%). One- and 2-year actual patient and graft survival was 100% and 100%.

CONCLUSION

Adult renal transplant recipients who are able to be maintained on spaced weaning have excellent outcomes. Patients with stable renal function who have reversal of weaning because of the development of DSA also have excellent outcomes. Routine monitoring for DSA may allow patients to avoid late rejection after spaced weaning.

Induction therapy in pediatric renal transplant recipients: an overview

Induction therapy to prevent the acute rejection of mismatched allografts with the ultimate aim of prolonging the life of the allograft has been the cornerstone of immunosuppression since the introduction of renal transplantation. Agents used for induction therapy have changed over time. Their role in transplantation is expanding to include corticosteroid avoidance and immunosuppression minimization. This review provides an overview of induction therapies for renal transplantation including historic therapies such as total lymphoid irradiation and Minnesota antilymphocyte globulin, and current therapies with polyclonal and monoclonal antibodies and chemical agents, with special emphasis on children. Data from adult studies, and pediatric studies whenever available, are summarized. A brief summary of experimental therapies with fingolimod and belatacept is provided. Historically, induction therapies were targeted at T cells. The role of induction therapies targeted at B cells is emerging in select groups of patients that include highly sensitized recipients and those receiving transplants from blood group incompatible donors. With the advent of newer maintenance immunosuppressive medications and with very low rates of acute rejection, induction protocols for renal transplantation need to be targeted so that excessive immunosuppression and infections are avoided. Several single-center and registry data analyses in children suggest that the addition of an interleukin (IL)-2 receptor antagonist may improve graft survival compared with no induction. The safety profile of IL-2 receptor antagonists is indistinguishable from that of placebo, with no apparent difference in the incidence of infection or post-transplant lymphoproliferative disease. IL-2 receptor antagonists and polyclonal lymphocyte-depleting antibodies offer equivalent efficacy in standard-risk populations. However, in high-risk patients, acute rejection rates and graft outcomes may be improved with the use of lymphocyte-depleting agents such as Thymoglobulin. However, cytomegalovirus infection and other infections may be more common with this therapy. Therefore, in patients at high risk of graft loss, Thymoglobulin may be the preferred choice for induction therapy, while for all other patients, IL-2 receptor antagonists should be considered the first-line choice for induction therapy. Newer lymphocyte-depleting agents such as alemtuzumab may be better utilized in minimization regimens involving one or two oral maintenance immunosuppressive agents.

Alemtuzumab pre-conditioning with tacrolimus monotherapy in pediatric renal transplantation

We employed antibody pre-conditioning with alemtuzumab and posttransplant immunosuppression with low-dose tacrolimus monotherapy in 26 consecutive pediatric kidney transplant recipients between January 2004 and December 2005. Mean recipient age was 10.7 +/- 5.8 years, 7.7% were undergoing retransplantation, and 3.8% were sensitized, with a PRA >20%. Mean donor age was 32.8 +/- 9.2 years. Living donors were utilized in 65% of the transplants. Mean cold ischemia time was 27.6 +/- 6.4 h. The mean number of HLA mismatches was 3.3 +/- 1.3. Mean follow-up was 25 +/- 8 months. One and 2 year patient survival was 100% and 96%. One and 2 year graft survival was 96% and 88%. Mean serum creatinine was 1.1 +/- 0.6 mg/dL, and calculated creatinine clearance was 82.3 +/- 29.4 mL/min/1.73 m(2). The incidence of pre-weaning acute rejection was 11.5%; the incidence of delayed graft function was 7.7%. Eighteen (69%) of the children were tapered to spaced tacrolimus monotherapy, 10.5 +/- 2.2 months after transplantation. The incidence of CMV, PTLD and BK virus was 0%; the incidence of posttransplant diabetes was 7.7%. Although more follow-up is clearly needed, antibody pre-conditioning with alemtuzumab and tacrolimus monotherapy may be a safe and effective regimen in pediatric renal transplantation.

Decreased incidence of acute rejection in adolescent kidney transplant recipients using antithymocyte induction and triple immunosuppression

BACKGROUND

Acute rejection is a frequent event in pediatric renal transplantation; it can diminish allograft function and affect long-term outcome. Recent data from the North American Pediatric Renal Transplant Cooperative Study indicates that the rate of acute rejection remains high despite current immunosuppressive regimens.

METHODS

In this retrospective series, we examined 37 pediatric renal transplant recipients who received induction doses of antithymocyte globulin combined with maintenance immunotherapy using tacrolimus, mycophenolate mofetil, and prednisone. The postoperative course was reviewed for initial and total hospital stay, number of rehospitalizations, evidence of posttransplant complications, graft fibrosis, and overall patient and graft survival.

RESULTS

Three episodes of acute rejection (8.1%) were recorded in the first year posttransplant. The median initial hospital stay for patients receiving a kidney transplant was 8 days. Patient and graft survival were 100% and 91.9% at 1 year, respectively. The incidence of viral infection (cytomegalovirus, BK virus, and Epstein-Barr virus) and posttransplant lymphoproliferative disease remained low. Urinary tract infection and fluid and electrolyte complications were the main causes of posttransplant hospitalization.

CONCLUSIONS

We conclude that induction with antithymocyte globulin and maintenance immunosuppression with tacrolimus, mycophenolate, and prednisone should be considered a valuable tool in the management of children undergoing renal transplantation.

Renal transplantation in children managed with lymphocyte depleting agents and low-dose maintenance tacrolimus monotherapy

OBJECTIVE

Describe the safety and efficacy of antithymocyte globulin or alemtuzumab preconditioning, steroid avoidance and reduced calcineurin inhibitor (CNI) immunosuppression in 34 children undergoing renal transplantation.

METHODS

ATG (n=8) or alemtuzumab (n=26) were infused at the time of transplantation. This was followed by low-dose twice a day tacrolimus monotherapy with consolidation to once daily dosing by 6 months and once every other day dosing by 12 months. Follow-up ranged from 0.5-2.9 years (mean 1.33 years), with a minimum of 6 months.

RESULTS

Both ATG and alemtuzumab were well tolerated. Lymphopenia occurred routinely and resolved after 3-6 months. Acute cellular rejection occurred in 9%; it was related to medical nonadherence in two patients and resulted in one graft loss at 1.5 years. Important adverse events included transient neutropenia in 10 children (none with serious infection), and autoimmune hemolytic anemia in two (resolved with a steroid course in both and conversion to sirolimus in one). Estimated glomerular filtration rate (e-GFR) was stable and averaged 88 mL/min/1.73 m2 at latest follow-up. Fifteen preadolescents had a greater increase in height Z-score at 1 year (1.3 vs. 0.5, P=0.001), and a higher e-GFR (94.8+/-21 vs. 76.6+/-20 ml/min/1.73 m2, P<0.05), when compared to case-matched historical controls who were weaned off steroids by 6 months after transplantation and received twice daily tacrolimus monotherapy.

CONCLUSION

This simple regimen appears safe, has a low risk for acute cellular rejection or other adverse effects, and is associated with excellent growth and renal function. Such a regimen may also improve compliance and limit CNI nephrotoxicity.

Alemtuzumab induction and tacrolimus monotherapy in pancreas transplantation: One- and two-year outcomes

BACKGROUND

Alemtuzumab (Campath-1H) induction with tacrolimus monotherapy has been shown to provide effective immunosuppression for kidney, liver, lung, and small bowel transplantation. This drug combination was evaluated in pancreas transplant recipients.

METHODS

Sixty consecutive pancreas transplants (30 simultaneous pancreas-kidney, 20 pancreas after kidney, and 10 pancreas alone) were carried out under this protocol between July 2003 to January 2005. The mean follow-up was 22 months (range 17-33).

RESULTS

One-year patient, pancreas, and kidney allograft survival were 95%, 93%, and 90%, respectively. With 22 months follow-up, patient, pancreas, and kidney survival were 94%, 89%, and 87%, respectively. The rejection rate was 30% (18/60), with four patients (7%) experiencing steroid-resistant rejection. Major infection occurred in three (5%) patients resulting in two (3.3%) deaths from disseminated histoplasmosis and a herpes virus infection. One patient with cryptococcal meningitis was successfully treated. Seven (11.7%) patients experienced cytomegalovirus infection, all of whom responded to treatment with ganciclovir. One (1.7%) case of polymorphic posttransplant lymphoproliferative disease was seen, which regressed with a temporary discontinuation of tacrolimus and high-dose ganciclovir. The mean serum creatinine of the 30 simultaneous pancreas-kidney transplants at one year posttransplant was 1.37+/-0.33 mg/ml. The preexisting creatinine in pancreas after kidney transplants was not adversely affected by this immunosuppressive protocol.

CONCLUSION

A single dose of perioperative alemtuzumab followed by daily tacrolimus monotherapy provides effective immunosuppression for pancreas transplantation, but the optimal use of this drug combination is not yet clear.

Acquired immunologic tolerance: with particular reference to transplantation

The first unequivocally successful bone marrow cell transplantation in humans was recorded in 1968 by the University of Minnesota team of Robert A. Good (Gatti et al. Lancet 2: 1366-1369, 1968). This achievement was a direct extension of mouse models of acquired immunologic tolerance that were established 15 years earlier. In contrast, organ (i.e. kidney) transplantation was accomplished precociously in humans (in 1959) before demonstrating its feasibility in any experimental model and in the absence of a defensible immunologic rationale. Due to the striking differences between the outcomes with the two kinds of procedure, the mechanisms of organ engraftment were long thought to differ from the leukocyte chimerism-associated ones of bone marrow transplantation. This and other concepts of alloengraftment and acquired tolerance have changed over time. Current concepts and their clinical implications can be understood and discussed best from the perspective provided by the life and times of Bob Good.

Immunosuppressive preconditioning or induction regimens : evidence to date

The success of solid organ transplantation has been directly related to the development of immunosuppressive drug therapies. Preconditioning or induction therapy was developed to reduce early immunological and nonimmunological renal injury, with the goal of increasing long-term graft survival. However, the routine induction of immunological tolerance to solid organ allograft is currently not achievable because of the morbidity and mortality related to the immunosuppressive regimens themselves. The different therapeutic preconditioning or induction agents and their associated effects on cellular rejection, graft survival outcomes and the need for multiagent post-transplant maintenance therapy are reviewed.

Opportunistic infections in 547 organ transplant recipients receiving alemtuzumab, a humanized monoclonal CD-52 antibody

BACKGROUND

Alemtuzumab is being increasingly used for the prevention and/or treatment of acute allograft rejection in organ transplant recipients. We assessed the risks of infection in, to our knowledge, the largest cohort and broadest range of organ transplant recipients yet reported to have received alemtuzumab.

METHODS

All patients who received alemtuzumab from September 2002 through March 2004, either as induction therapy at the time of transplantation or for the treatment of rejection, were evaluated for the development of an opportunistic infection (OI) until death or for 12 months after receipt of the last dose of alemtuzumab.

RESULTS

A total of 547 recipients were included, 65% of whom received alemtuzumab for induction therapy only. Overall, 56 recipients (10%) developed 62 OIs, including cytomegalovirus disease (n = 16), BK virus infection (n=12), posttransplantation lymphoproliferative disease (n=5), human herpesvirus 6 infection (n=1), parvovirus infection (n=1), esophageal candidiasis (n=12), cryptococcosis (n=2), invasive mold infection (n=4), Nocardia infection (n=4), mycobacterial infection (n=3), Balamuthia mandrillaris infection (n=1), and toxoplasmosis (n=1). Patients who received alemtuzumab for induction therapy were significantly less likely to develop an OI, compared with patients who received alemtuzumab for rejection therapy (4.5% vs. 21%; P<.001). Independent predictors of the development of an OI were administration of alemtuzumab for rejection therapy (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.8-6.8; P<.001), allograft failure (OR, 2.1; 95% CI, 1.1-4.4; P=.04), and receipt of a lung transplant (OR, 3.7; 95% CI, 1.7-8.0; P=.001) or an intestinal transplant (OR, 8.3; 95% CI, 3.5-19.5; P<.001).

CONCLUSIONS

Patients who received alemtuzumab for the treatment of allograft rejection were significantly more likely to develop an OI, compared with patients who received alemtuzumab for induction therapy only. Such data have implications for new antimicrobial prophylactic strategies.

Living donor renal transplantation using alemtuzumab induction and tacrolimus monotherapy

Alemtuzumab was used as an induction agent in 205 renal transplant recipients undergoing 207 living donor renal transplants. All donor kidneys were recovered laparoscopically. Postoperatively, patients were treated with tacrolimus monotherapy, and immunosuppression was weaned when possible. Forty-seven recipients of living donor renal transplants prior to the induction era who received conventional triple drug immunosuppression without antibody induction served as historic controls. The mean follow-up was 493 days in the alemtuzumab group and 2101 days in the historic control group. Actuarial 1-year patient and graft survival were 98.6% and 98.1% in the alemtuzumab group, compared to 93.6% and 91.5% in the control group, respectively. The incidence of acute cellular rejection (ACR) at 1 year was 6.8% in the alemtuzumab group and 17.0% (p < 0.05) in the historic control group. Most (81.3%) episodes of ACR in the alemtuzumab group were Banff 1 (a or b) and were sensitive to steroid pulses for the treatment of rejection. There was no cytomegalovirus disease or infection. The incidence of delayed graft function was 0%, and the incidence of posttransplant insulin-dependent diabetes mellitus was 0.5%. This study represents the largest series to date of live donor renal transplant recipients undergoing alemtuzumab induction, and confirms the short-term safety and efficacy of this approach.