Population pharmacokinetics and exposure-response relationships for basiliximab in kidney transplantation. The U.S. Simulect Renal Transplant Study Group

Basiliximab as maintenance immunosuppression in heart transplant recipients: A single pediatric center experience

BACKGROUND

Pediatric heart transplant recipients are at risk for complications from prolonged exposure to immunosuppressive drugs, pharmacokinetic challenges in maintaining consistent immunosuppression, and medication non-adherence. Basiliximab (BAS), an interleukin-2 receptor antagonist, is used for induction therapy across many pediatric heart transplant centers, but use as maintenance immunosuppression has not been well described.

METHODS

This was a retrospective, single pediatric center cohort study of heart transplant recipients who received BAS for maintenance immunosuppression (defined as >2 monthly doses) from January 1, 2011, to December 31, 2021.

RESULTS

Ten patients met study criteria with a median age of 17.5 (5-22) years and median 9.6 (1.2-18.9) years since transplant at time of BAS initiation. The primary indications for BAS use were recurrent rejection (n = 4), fluctuating immunosuppression levels (n = 3), and renal dysfunction (n = 3). A median of 5.5 (3-32) monthly BAS doses were received. Three patients had a rejection event while on BAS. Calcineurin inhibitor exposure was reduced in 70% of patients. Three of the 10 patients were alive at last follow-up. There was one documented infection during BAS use, and no hypersensitivity reactions.

CONCLUSIONS

Monthly BAS infusions were well tolerated and allowed for reduced calcineurin inhibitor exposure in most patients. Mortality commonly occurred despite BAS use, potentially reflecting the acuity of this patient cohort. BAS can be considered for maintenance immunosuppression in pediatric patients with fluctuating immunosuppressive levels and/or renal dysfunction. More studies are needed to determine long-term outcomes and explore expanded use of BAS in the pediatric heart transplant population.

Model-informed precision dosing to optimise immunosuppressive therapy in renal transplantation

Immunosuppressive therapy is pivotal for sustained allograft and patient survival after renal transplantation. However, optimally balanced immunosuppressive therapy is challenged by between-patient and within-patient pharmacokinetic (PK) variability. This could warrant the application of personalised dosing strategies to optimise individual patient outcomes. Pharmacometrics, the science that investigates the xenobiotic-biotic interplay using computer-aided mathematical modelling, provides options to describe and quantify this PK variability and enables identification of patient characteristics affecting immunosuppressant PK and treatment outcomes. Here, we review and critically appraise the available pharmacometric model-informed dosing solutions for the typical immunosuppressants in modern renal transplantation, to guide their initial and subsequent dosing.

Implications for body weight extremes in solid organ transplantation

The pharmacokinetic profiles of medications are altered in overweight and underweight patients, but few studies have described these differences in patients with body mass index extremes. As solid organ transplant programs expand their candidate selection criteria to accommodate a growing population of patients with weight extremes, it has become imperative to understand and evaluate the impact weight extremes have on the pharmacokinetics of life-sustaining immunosuppression in this population. This review will describe pharmacokinetic and dosing considerations for weight extremes in solid organ transplant recipients, including changes following bariatric surgeries, non-pharmacologic and pharmacologic management strategies for weight loss and gain, and potential drug-drug interactions with popular weight management products.

Influence of Induction Therapy Using Basiliximab With Delayed Tacrolimus Administration in Heart Transplant Recipients - Comparison With Standard Tacrolimus-Based Triple Immunosuppression

BACKGROUND

Appropriate indications and protocols for induction therapy using basiliximab have not been fully established in heart transplant (HTx) recipients. This study elucidated the influence of induction therapy using basiliximab along with delayed tacrolimus (Tac) initiation on the outcomes of high-risk HTx recipients.Methods and Results:A total of 86 HTx recipients treated with Tac-based immunosuppression were retrospectively reviewed. Induction therapy was administered to 46 recipients (53.5%) with impaired renal function, pre-transplant sensitization, and recipient- and donor-related risk factors (Induction group). Tac administration was delayed in the Induction group. Induction group subjects showed a lower cumulative incidence of acute cellular rejection grade ≥1R after propensity score adjustment, but this was not significantly different (hazard ratio [HR]: 0.63, 95% confidence interval [CI]: 0.37-1.08, P=0.093). Renal dysfunction in the Induction group significantly improved 6 months post-transplantation (P=0.029). The cumulative incidence of bacterial or fungal infections was significantly higher in the Induction group (HR: 10.6, 95% CI: 1.28-88.2, P=0.029).

CONCLUSIONS

These results suggest that basiliximab-based induction therapy with delayed Tac initiation may suppress mild acute cellular rejection and improve renal function in recipients with renal dysfunction, resulting in its non-inferior outcome, even in high-risk patients, when applied to the appropriate recipients. However, it should be carefully considered in recipients at a high risk of bacterial and fungal infections.

Use of Basiliximab and Daclizumab in Kidney Transplantation

Kidney transplantation represents a major medical victory in patients with whom dialysis and medical therapy have failed. To increase survival rates and optimize the use of limited organs, both patient care and immunosuppression therapy must be improved. Reduction in rejection episodes or severity of rejection may ultimately improve long-term allograft survival. Traditional engineered monoclonal antibodies have been associated with severe cytokine release reactions and an increased risk of opportunistic infections. Basiliximab and daclizumab are chimeric and humanized monoclonal antibodies that inhibit thymus-dependent lymphocyte proliferation. Interleukin 2 also affects the proliferation of natural killer cells, macrophages and monocytes, bursa-equivalent lymphocytes, epidermal dendritic cells, and lymphokine-activated killer cells. Interleukin-2 receptor antagonists have been shown to reduce the incidence of acute rejection without increasing the incidence of opportunistic infections or malignancy. Further studies are needed to evaluate the overall effect of these agents on long-term patient and allograft survival.

A Rationale for Age-Adapted Immunosuppression in Organ Transplantation

Demographic changes are associated with a steady increase of older patients with end-stage organ failure in need for transplantation. As a result, the majority of transplant recipients are currently older than 50 years, and organs from elderly donors are more frequently used. Nevertheless, the benefit of transplantation in older patients is well recognized, whereas the most frequent causes of death among older recipients are potentially linked to side effects of their immunosuppressants.Immunosenescence is a physiological part of aging linked to higher rates of diabetes, bacterial infections, and malignancies representing the major causes of death in older patients. These age-related changes impact older transplant candidates and may have significant implications for an age-adapted immunosuppression. For instance, immunosenescence is linked to lower rates of acute rejections in older recipients, whereas the engraftment of older organs has been associated with higher rejection rates. Moreover, new-onset diabetes mellitus after transplantation is more frequent in the elderly, potentially related to corticosteroids, calcineurin inhibitors, and mechanistic target of rapamycin inhibitors.This review presents current knowledge for an age-adapted immunosuppression based on both, experimental and clinical studies in and beyond transplantation. Recommendations of maintenance and induction therapy may help to improve graft function and to design future clinical trials in the elderly.

The role of basiliximab in the evolving renal transplantation immunosuppression protocol

Basiliximab is a chimeric mouse-human monoclonal antibody directed against the alpha chain of the interleukin-2 (IL-2) receptor on activated T lymphocytes. It was shown in phase III trials to reduce the number and severity of acute rejection episodes in the first year following renal transplantation in adults and children, with a reasonable cost-benefit ratio. The drug does not increase the incidence of opportunistic infections or malignancies above baseline in patients treated with conventional calcineurin inhibitor-based immunosuppression. In the field of renal transplantation, basiliximab does not increase kidney or patient survival, despite the reduction in the number of rejection episodes. Basiliximab may reduce the incidence of delayed graft function. In comparison with lymphocyte-depleting antibodies basiliximab appears to have equal efficacy in standard immunological risk patients. Recently, IL-2 receptor monoclonal antibodies have been used with the objective of reducing or eliminating the more toxic elements of the standard immunosuppression protocol. Several trials have incorporated basiliximab in protocols designed to avoid or withdraw rapidly corticosteroids, as well as protocols which substitute target-of-rapamycin (TOR) inhibitors for calcineurin inhibitors.

Pediatric Dosing and Body Size in Biotherapeutics

Although pediatric doses for biotherapeutics are often based on patients' body weight (mg/kg) or body surface area (mg/m²), linear body size dose adjustment is highly empirical. Growth and maturity are also important factors that affect the absorption, distribution, metabolism and excretion (ADME) of biologics in pediatrics. The complexity of the factors involved in pediatric pharmacokinetics lends to the reconsideration of body size based dose adjustment. A proper dosing adjustment for pediatrics should also provide less intersubject variability in the pharmacokinetics and/or pharmacodynamics of the product compared with no dose adjustment. Biological proteins and peptides generally share the same pharmacokinetic principle with small molecules, but the underlying mechanism can be very different. Here, pediatric and adult pharmacokinetic parameters are compared and summarized for selected biotherapeutics. The effect of body size on the pediatric pharmacokinetics for these biological products is discussed in the current review.

Clinical pharmacokinetics of therapeutic monoclonal antibodies

Monoclonal antibodies (mAbs) have been used in the treatment of various diseases for over 20 years and combine high specificity with generally low toxicity. Their pharmacokinetic properties differ markedly from those of non-antibody-type drugs, and these properties can have important clinical implications. mAbs are administered intravenously, intramuscularly or subcutaneously. Oral administration is precluded by the molecular size, hydrophilicity and gastric degradation of mAbs. Distribution into tissue is slow because of the molecular size of mAbs, and volumes of distribution are generally low. mAbs are metabolized to peptides and amino acids in several tissues, by circulating phagocytic cells or by their target antigen-containing cells. Antibodies and endogenous immunoglobulins are protected from degradation by binding to protective receptors (the neonatal Fc-receptor [FcRn]), which explains their long elimination half-lives (up to 4 weeks). Population pharmacokinetic analyses have been applied in assessing covariates in the disposition of mAbs. Both linear and nonlinear elimination have been reported for mAbs, which is probably caused by target-mediated disposition. Possible factors influencing elimination of mAbs include the amount of the target antigen, immune reactions to the antibody and patient demographics. Bodyweight and/or body surface area are generally related to clearance of mAbs, but clinical relevance is often low. Metabolic drug-drug interactions are rare for mAbs. Exposure-response relationships have been described for some mAbs. In conclusion, the parenteral administration, slow tissue distribution and long elimination half-life are the most pronounced clinical pharmacokinetic characteristics of mAbs.

Interleukin 2 receptor antagonists for kidney transplant recipients

BACKGROUND

Interleukin 2 receptor antagonists (IL2Ra) are used as induction therapy for prophylaxis against acute rejection in kidney transplant recipients. Use of IL2Ra has increased steadily since their introduction, but the proportion of new transplant recipients receiving IL2Ra differs around the globe, with 27% of new kidney transplant recipients in the United States, and 70% in Australasia receiving IL2Ra in 2007.

OBJECTIVES

To systematically identify and summarise the effects of using an IL2Ra, as an addition to standard therapy, or as an alternative to another immunosuppressive induction strategy.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE to identify new records, and authors of included reports were contacted for clarification where necessary.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing IL2Ra to placebo, no treatment, other IL2Ra or other antibody therapy.

DATA COLLECTION AND ANALYSIS

Data was extracted and assessed independently by two authors, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) and continuous outcomes as mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 71 studies (306 reports, 10,537 participants). Where IL2Ra were compared with placebo (32 studies; 5,784 patients) graft loss including death with a functioning graft was reduced by 25% at six months (16 studies: RR 0.75, 95% CI 0.58 to 0.98) and one year (24 studies: RR 0.75, 95% CI 0.62 to 0.90), but not beyond this. At one year biopsy-proven acute rejection was reduced by 28% (14 studies: RR 0.72, 95% CI 0.64 to 0.81), and there was a 19% reduction in CMV disease (13 studies: RR 0.81, 95% CI 0.68 to 0.97). There was a 64% reduction in early malignancy within six months (8 studies: RR 0.36, 95% CI 0.15 to 0.86), and creatinine was lower (7 studies: MD -8.18 micromol/L 95% CI -14.28 to -2.09) but these differences were not sustained.When IL2Ra were compared to ATG (16 studies, 2211 participants), there was no difference in graft loss at any time point, or for acute rejection diagnosed clinically, but the was benefit of ATG therapy over IL2Ra for biopsy-proven acute rejection at one year (8 studies:, RR 1.30 95% CI 1.01 to 1.67), but at the cost of a 75% increase in malignancy (7 studies: RR 0.25 95% CI 0.07 to 0.87) and a 32% increase in CMV disease (13 studies: RR 0.68 95% CI 0.50 to 0.93). Serum creatinine was significantly lower for IL2Ra treated patients at six months (4 studies: MD -11.20 micromol/L 95% CI -19.94 to -2.09). ATG patients experienced significantly more fever, cytokine release syndrome and other adverse reactions to drug administration and more leucopenia but not thrombocytopenia. There were no significant differences in outcomes according to cyclosporine or tacrolimus use, azathioprine or mycophenolate, or to the study populations baseline risk for acute rejection. There was no evidence that effects were different according to whether equine or rabbit ATG was used.

AUTHORS' CONCLUSIONS

Given a 38% risk of rejection, per 100 recipients compared with no treatment, nine recipients would need treatment with IL2Ra to prevent one recipient having rejection, 42 to prevent one graft loss, and 38 to prevent one having CMV disease over the first year post-transplantation. Compared with ATG treatment, ATG may prevent some experiencing acute rejection, but 16 recipients would need IL2Ra to prevent one having CMV, but 58 would need IL2Ra to prevent one having malignancy. There are no apparent differences between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effects.

Anti-interleukin-2 receptor antibodies-basiliximab and daclizumab-for the prevention of acute rejection in renal transplantation

The use of antibody induction after kidney transplantation has increased from 25% to 63% in the past decade and roughly one half of the induction agent used is anti-interleukin-2 receptor antibody (IL-2RA, ie, basiliximab or daclizumab). When combined with calcineurin inhibitor (CNI)-based immunosuppression, IL-2RAs have been shown to reduce the incidence of acute rejection, one of the predictors of poor graft survival, without increasing risks of infections and malignancies in kidney transplantation. For low-immunological-risk patients, IL-2RAs, as compared with lymphocyte-depleting antibodies, are equally efficacious and have better safety profiles. For high-risk patients, however, IL-2RAs may be inferior to lymphocyte-depleting antibodies for the prophylaxis of acute rejection. In an effort to reduce toxicities of other immunosuppressive medications without increasing the risk of acute rejection and chronic graft loss, IL-2RAs have often been combined with steroid- and CNI-sparing immunosuppression protocols. More data support the benefits of early steroid withdrawal with IL-2RA in low-risk patients, but preferred induction therapy for high-risk patients has yet to be determined. Although CNI-sparing protocols with IL-2RA may preserve renal function and improve long-term survival in selected patients, further studies are needed to identify those who benefit most from this strategy.

Pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on mycophenolate mofetil comedication

BACKGROUND

The aim of this substudy within a prospective, multicenter, placebo-controlled trial was to assess the pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on comedication with mycophenolate mofetil (MMF).

METHODS

Eighty-two patients aged 3 to 18 years, receiving cyclosporine microemulsion, MMF, corticosteroids, and basiliximab or placebo were investigated. Basiliximab serum concentrations were determined by ELISA, CD25+, and CD122+ T lymphocytes by flow cytometry.

RESULTS

Basiliximab clearance adjusted to body surface area was significantly (P<0.05) greater in children versus adults, but the relatively higher basiliximab dose given to children yielded similar exposure compared with adolescents. A cross-study comparison revealed that MMF reduced basiliximab clearance and prolonged CD25 saturation duration from approximately 5 weeks in the absence of MMF to 10 weeks in the presence of MMF. Basiliximab led to a marked reduction of CD25+ T-cell fraction during the first 8 to 10 weeks posttransplant, but did not specifically affect CD122+ T cells. The majority of biopsy-proven acute rejection episodes (BPAR) were observed after interleukin (IL) 2-R desaturation, whereas about a quarter of BPARs occurred despite adequate IL2-R blockade.

CONCLUSIONS

The currently recommended basiliximab dose for pediatric patients, when used with cyclosporine microemulsion and corticosteroids, yielded adequate drug exposure in children and adolescents also under MMF comedication. The observation that about a quarter of BPARs occurred despite adequate IL2-R blockade suggests that another T-cell activation pathway independent of the IL-2/IL-2R pathway is operative, for example, the IL-15 signaling pathway.

Anaphylactic reaction after initial exposure of Basiliximab: case reports

Basiliximab is potent, relatively safe immunosuppressive induction agent used in transplantation. Prophylactic use at the time of transplantation has been advocated to improve allograft outcomes. We report two cases of kidney transplant recipients with anaphylactic reactions after initial exposure to Basiliximab.

Basiliximab versus daclizumab combined with triple immunosuppression in deceased donor renal graft recipients

In this prospective, randomized, open-label, single-center study, we compared the efficacy and safety of two anti-interleukin-2 receptor monoclonal antibodies among adult recipients of at least 1 HLA-mismatched deceased donor renal grafts. Eligible patients were randomized to induction with either basiliximab or daclizumab. Both groups received cyclosporine microemulsion (CsA Neoral), mycophenolate mofetil, and methylprednisolone. An intent-to-treat analysis of 1-year data assessed the incidence of acute rejection episodes, the renal graft function, the safety, and the patient and graft survivals. Among 127 patients, six (10.0%) and seven (11.5%) patients experienced biopsy-confirmed acute rejection at 12 months, in the basiliximab and the daclizumab groups, respectively. Two renal grafts were lost in the basiliximab and six in the daclizumab cohort, one of them due to rejection. One basiliximab and two daclizumab patients died. Hospital treatment was required for 25 and 33 infections in basiliximab and daclizumab groups, respectively. One basal cell carcinoma of skin was detected. One hypersensitivity reaction was observed with daclizumab. At 12 months, serum creatinine was 101+/-28 micromol/L with basiliximab and 109+/-41 micromol/L with daclizumab. Patient survival was 98.4% with basiliximab and 96.7% with daclizumab, and graft survival was 96.8% versus 90.8%, respectively. No significant differences were observed between the groups. Basiliximab or daclizumab combined with triple therapy was an efficient and safe immunosuppression strategy, demonstrated with low incidence of acute rejection episodes, an acceptable adverse event profile, excellent graft function, and high survival rates in adult recipients within the first year after deceased donor renal transplantation.

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.

Lower Risk of Infectious Deaths in Cardiac Transplant Patients Receiving Basiliximab Versus Anti-thymocyte Globulin as Induction Therapy

BACKGROUND

Conventional antibody induction therapy is currently used in heart transplantation despite safety concerns. This 6-month, prospective, randomized, multicenter, open-label study examined whether basiliximab offers a tolerability benefit compared with anti-thymocyte globulin (ATG) while maintaining similar efficacy in de novo heart transplant recipients.

METHODS

Adult heart transplant recipients were randomized to receive basiliximab (20 mg on Day 0 and Day 4) or ATG (2.5 mg/kg/day for 3 to 5 days) with cyclosporine, mycophenolate mofetil and steroids. The primary safety end-point was a composite of serum sickness, fever, cutaneous rash, anaphylaxis, infection, thrombocytopenia, leukopenia and post-transplant proliferative disease. Efficacy was assessed by a composite end-point of death, graft loss, acute rejection Grade > 1B, acute rejection associated with hemodynamic compromise or treated with antibody therapy, or loss to follow-up, whichever occurred first.

RESULTS

Eighty patients were randomized and analyzed. By Month 6, the incidence of the composite safety end-point was significantly lower with basiliximab than with ATG (50.0% vs 78.6%, p = 0.01), and infectious death was less frequent in the basiliximab group (0 of 38 vs 6 of 42, p = 0.027). The composite efficacy end-point occurred in 24 patients (63.2%) in the basiliximab arm vs 28 patients (66.7%, p = not significant [NS]) receiving ATG. Acute rejection episodes of Grade > or = 1B were reported with similar frequency (50% with basiliximab vs 45.2% with ATG, p = NS); 7 patients (18.4%) in the basiliximab group and 3 (7.1%) in the ATG group had rejection Grade > or = 3A.

CONCLUSIONS

These results suggest that basiliximab offers improved tolerability with similar efficacy compared with current polyclonal antibody induction therapy in de novo heart transplant patients.

The role of basiliximab induction therapy in organ transplantation

Basiliximab is a chimeric monoclonal antibody that selectively binds to the alpha-subunit (CD25) of IL-2 receptors on the surface of activated T lymphocytes, and is a highly effective prophylaxis agent against rejection in organ transplant recipients. Its pharmacokinetic profile is characterized by a biphasic and slow clearance with long terminal half-life and a volume of distribution within the central compartment and outside the circulatory system. Basiliximab induction demonstrated an excellent safety profile, with no increase in the incidence of malignancy, infections or death. It has also been used effectively in high-risk recipients, steroid-sparing and steroid-minimization protocols, and in post-transplant patients with renal dysfunction who would benefit from delayed introduction of calcineurin inhibitors. Basiliximab induction therapy given at days 0 and 4 after transplantation appears to be safe and cost-effective for immunoprophylaxis in solid organ transplant recipients, specifically in kidney and liver transplantation, when given in conjunction with dual or triple immunosuppressive therapy.

Effective Immunoprophylaxis With Basiliximab Plus Triple Therapy in Renal Transplantation: Five-Year Single-Center Experience

We studied prospectively the efficacy and safety of basiliximab combined with triple immunosuppression in adult recipients of > or = 1 HLA-mismatched deceased donor renal grafts. All studied patients received equal immunosuppressive drugs: 20 mg infusion of basiliximab on day 0 and on day 4, cyclosporine microemulsion (Neoral), mycophenolate mofetil, and methylprednisolone. An analysis of 1-year data assessed the incidence of acute rejection episodes, safety of this therapy, renal graft function, and patient and graft survivals. One hundred seventy-two patients were studied. The HLA-antigen mismatches were 2.9 +/- 0.9 (mean +/- SD), and the cold ischemia time was 22.0 +/- 7.5 hours. Fifty-three (31.5%) patients experienced delayed graft function. At 12 months, 5 (3.0%) patients experienced acute rejection. Six renal grafts were lost, but not from rejection. Two patients died. Sixty-six infections required treatment in the hospital. One carcinoma of cervix (in situ) and two basal cell carcinomas of skin were detected. Hypersensitivity reactions and cytokine-release syndrome were not observed. At 12 months, serum creatinine was significantly higher (119 +/- 46 micromol/L; P < .001) in patients with delayed graft function than in patients with immediate graft function (99 +/- 26 micromol/L). Patient and graft survivals were 98.8% and 97.1%, respectively. Basiliximab combined with this triple therapy was an efficient and safe immunosuppression strategy, demonstrated with very low incidence of acute rejections, an acceptable adverse event profile, excellent graft function, and high short-term survival rates in adult recipients of deceased donor renal transplant.

Disparities in solid organ transplantation for ethnic minorities: facts and solutions

The Diversity and Minority Affairs Committee of the American Society of Transplantation (AST) convened a symposium to examine organ transplantation in underserved and minority populations. The goals of the meeting included 'benchmarking' of solid organ transplantation among minority populations, review of the epidemiology of end-organ damage, exploration of barriers to transplantation services and development of approaches to eliminate disparities. Participants noted that minority populations were more likely to be adversely affected by limited preventive medical care, lack of counseling regarding transplant options, and delays in transplant referrals for organ transplantation. These features largely reflect economic disadvantage as well as the reduced presence of minority professionals with training in transplant-related specialties. Participants in the conference noted that recent changes in organ allocation policies had improved access to minority individuals once listed for renal transplantation. Similar advances will be needed for other organs to address inequities in pretransplant care and underrepresentation of minorities among transplant professionals. The biologic basis of differences in transplant outcomes for minority recipients has not been adequately studied. Research funds must be targeted to address biologic mechanisms underlying disparate transplant outcomes including the impacts of environment, education, poverty and lifestyle choices.

Immunosuppressive agents in solid organ transplantation: Mechanisms of action and therapeutic efficacy

Effective immunosuppression is an essential pre-requisite for successful organ transplantation and improvements in outcome after transplantation have to a large extent been dependent on developments in immunosuppressive therapy. Here we provide an overview of the different immunosuppressive agents currently used in solid organ transplantation. A historical perspective on the development of immunosuppression for organ transplantation is followed by a review of the individual agents, with a focus on their mechanism of action and efficacy. Steroids, anti-proliferative agents (azathioprine and mycophenolate), calcineurin inhibitors (cyclosporine and tacrolimus) and TOR inhibitors (sirolimus and everolimus) are discussed along with both polyclonal and monoclonal antibody preparations. Many of the key clinical trials that underpin current clinical usage of these agents are described and side-effects of the different agents are highlighted. Finally, a number of newer agents still in various stages of clinical development are briefly considered.

Basiliximab and Mycophenolate Mofetil in Combination With Low-Dose Cyclosporine and Methylprednisolone Effectively Prevent Acute Rejection in Kidney Transplant Recipients

The aim of the study was to analyze whether immunosuppressive treatment with basiliximab and mycophenolate mofetil (MMF), allowed a reduction in methylprednisolone and cyclosporine dosages without increasing the incidence of acute rejection episodes, reducing 1-year graft and patient survivals, or increasing the rates of infections and malignancy in the first year. The two groups were group A (n = 72), treated with methylprednisolone and cyclosporine and in the first 2 weeks with azathioprine; group B (n = 72), treated with basiliximab, MMF, and low-dose cyclosporine and methylprednisolone. The patients were followed for 1 year. The incidence of acute rejection episodes in the first year was significantly lower in group B (2.8%) than group A (12.5%; P < .05). The cumulative methylprednisolone dose, the daily dose, and the average cyclosporine trough blood level were significantly lower in group B (P < .001). One-year serum creatinine was significantly lower in group B (112 +/- 45 micromol/L) than group A (138 +/- 51 micromol/L; P < .01). One-year graft survival was 91.7% in group A and 98.6% in group B. One-year patient survival was 98.6% in group A and 100% in group B. The groups did not differ significantly in the incidence of bacterial, viral, or fungal infections. Immunosuppression with basiliximab and MMF allowed a reduction in cyclosporine and methylprednisolone dosages and was associated with significantly lower incidences of acute rejections episodes with better graft function in the first year as opposed to immunosuppression with higher doses of cyclosporine and methylprednisolone alone. Both immunosuppressive regimens showed the same infection rates and did not differ significantly in the occurrence of malignant diseases within the first year.

The renal-sparing efficacy of basiliximab in adult living donor liver transplantation

The purpose of this study is to find out whether basiliximab administration will improve postoperative renal function by delaying the start of tacrolimus and decreasing of dosage requirement for tacrolimus in adult living donor liver transplantation (LDLT). Forty-five adult LDLT recipients were enrolled in the study. The induction group (n = 27) was given basiliximab 20 mg on days 0 and 4; tacrolimus administration was delayed until renal function improved. The control group (n = 18) did not receive basiliximab; tacrolimus was given on the first postoperative day. Trough levels of tacrolimus in the induction and control groups were aimed to be maintained at 5-10 ng/ml and 10-15 ng/ml during the first week after transplant, respectively. The median follow-up was 22 months (range 10-34 months). The preoperative conditions were poorer in the induction group (Child C, 56% vs. 33%, P = 0.01; UNOS 2a, 15% vs. 0%, P = 0.02). The intraoperative blood loss was also higher in the induction group than in the control group (median 2,180 ml vs. 495 ml, P < 0.01). The median delay in tacrolimus administration in the induction group was 36 hours (range 24-108 hours). Serum creatinine levels at second and third postoperative months were significantly lower in the induction group. The creatinine clearance rate in the induction group was higher at the third month posttransplant (median 72 vs. 57 ml/minute, P = 0.04). The incidence of renal insufficiency was significantly lower in the induction group at the third month posttransplant (26% vs. 67%, P < 0.01). Blood cholesterol level at the sixth month posttransplant was lower in the induction group (median 152 vs. 196 mg/dl P = 0.03). The incidences of acute cellular rejection, bacteremia, and cytomegalovirus (CMV) infection were similar in both groups. In conclusion, for pretransplant critical patients with more intraoperative blood loss, basiliximab induction could prevent early renal dysfunction by delaying the start of tacrolimus and reducing the dose requirement of tacrolimus without increasing graft rejection and infection. Furthermore, it also improved renal function as well as lowered cholesterol levels within 6 months after transplantation.

A Multicenter, Prospective, Randomized, Double-Blind Trial of Basiliximab in Heart Transplantation

BACKGROUND

The role and pharmacokinetics of interleukin-2 (IL-2) monoclonal antibodies (mAbs) in heart transplantation remain unclear. This 1-year double-blind, randomized, placebo-controlled study evaluated safety, tolerability, and pharmacokinetics of the IL-2 mAb basiliximab with cyclosporine, mycophenolate mofetil, and steroids in adult de novo heart transplant recipients.

METHODS

Fifty-six patients received either basiliximab (20 mg) or placebo on Days 0 and 4 post-transplantation. Safety assessments included adverse events, serious adverse events, and infections. The time to and severity of biopsy-proven acute rejection (BPAR) were also assessed.

RESULTS

Basiliximab was generally well tolerated. There were no significant differences between treatment groups with respect to adverse event profiles, serious adverse events (84.0% vs 61.3%), or infections (84% vs 74.2%). The mean number of days to first BPAR was longer with basiliximab (73.7 +/- 59.68) than placebo (40.6 +/- 53.30) at 6 months, but not statistically significant (trend). The duration that basiliximab concentrations exceeded the CD25 saturation threshold averaged 38 +/- 13 days. Patients with rejection did not clear basiliximab faster or have shorter durations of saturation than rejection-free patients. None of the patients screened had detectable anti-idiotype antibodies.

CONCLUSIONS

These pilot results describe the pharmacokinetics of basiliximab and show that basiliximab appears to be tolerated with a similar safety profile to placebo in adult de novo heart transplant recipients. Larger scale clinical trials are feasible and warranted.

Quadruple immunosuppression with basiliximab, tacrolimus, mycophenolate mofetil and prednisone is safe and effective for renal transplantation

INTRODUCTION

Recent immunosuppression with tacrolimus and mycophenolate mofetil has improved the results of renal transplantation. In this study, we analyzed the effect and safety of basiliximab as an induction therapy.

MATERIAL AND METHODS

Forty-nine kidney recipients were given tacrolimus, mycophenolate mofetil and prednisone (non-Bas group), and 31 recipients were given basiliximab as an induction therapy in addition to the triple immunosuppressants (Bas group). Graft function, incidence of acute rejection (AR), findings of protocol graft biopsy and adverse effects were compared.

RESULTS

Serum creatinine within 1 yr post-transplant was comparable between the two groups. Incidence of biopsy-proven AR within 6 months post-transplant was less in the Bas group than in the non-Bas group. Borderline change at 3 months post-transplant was less in the Bas group when compared to the non-Bas group. The frequency and severity of tubulitis were higher in the non-Bas group than in the Bas group. The addition of basiliximab did not increase opportunistic infection, but reduced tacrolimus nephrotoxicity.

CONCLUSION

The addition of basiliximab to the tacrolimus-based triple immunosuppressive regimen enabled us to reduce the doses of immunosuppressants and tacrolimus nephrotoxicity without increasing early rejection or infection. This regimen is safe and effective for application during the early period after renal transplantation.

Antibody pharmacokinetics and pharmacodynamics

The U.S. Food and Drug administration (FDA) has approved several polyclonal antibody preparations and at least 18 monoclonal antibody preparations (antibodies, antibody fragments, antibody fusion proteins, etc.). These drugs, which may be considered as a diverse group of therapeutic proteins, are associated with several interesting pharmacokinetic characteristics. Saturable binding with target antigen may influence antibody disposition, potentially leading to nonlinear distribution and elimination. Independent of antigen interaction, concentration-dependent elimination may be expected for IgG antibodies, due to the influence of the Brambell receptor, FcRn, which protects IgG from catabolism. Antibody administration may induce the development of an endogenous antibody response, which may alter the pharmacokinetics of the therapeutic antibody. Additionally, the pharmacodynamics of antibodies are also complex; these drugs may be used for a wide array of therapeutic applications, and effects may be achieved by a variety of mechanisms. This article provides an overview of many of the complexities associated with antibody pharmacokinetics and pharmacodynamics.

Anti-interleukin-2 receptor antibodies for the prevention of rejection in pediatric renal transplant patients: current status

The anti-interleukin-2 receptor (anti-IL-2R) antibody therapy is an exciting approach to the prevention of acute rejection after renal allograft transplantation whereby immunosuppression is exerted by a selective and competitive inhibition of IL-2-induced T cell proliferation, a critical pathway of allorecognition. The anti-IL-2R antibodies specifically block the alpha-subunit of the IL-2R on activated T cells, and prevent T cell proliferation and activation of the effector arms of the immune system. The anti-IL-2R antibodies are used as induction therapy, immediately after renal transplantation, for prevention of acute cellular rejection in children and adults. During acute rejection, the IL-2Ralpha chain is no longer expressed on T cells; thus, the antibodies cannot be used to treat an existing acute rejection. Two anti-IL-2R monoclonal antibodies are currently in clinical use: daclizumab and basiliximab. In placebo-controlled phase III clinical trials in adults, daclizumab and basiliximab in combination with calcineurin inhibitor-based immunosuppression, significantly reduced the incidence of acute rejection and corticosteroid-resistant acute rejection without increasing the risk of infectious or malignant complications, and neither antibody was associated with the cytokine-release syndrome. Children who receive calcineurin inhibitors and corticosteroids for maintenance immunosuppression, as well as children who receive augmented immunosuppression to treat acute rejection, are at increased risk of growth impairment, hypertension, hyperlipidemia, lymphoproliferative disorders, diabetes mellitus, and cosmetic changes. In older children, the cosmetic adverse effects frequently reduce compliance with the treatment, and subsequently increase the risk of allograft loss. Being effective and well tolerated in children, the anti-IL-2R antibodies reduce the need for calcineurin inhibitors while maintaining the overall efficacy of the regimen; thus, the anti-IL-2R antibodies increase the safety margin (less toxicity, fewer adverse effects) of the baseline immunosuppression. Secondly, the anti-IL-2R antibodies decrease the need for corticosteroids and muromonab CD3 (OKT3) in children as a result of decreased incidence of acute rejection. The recommended pediatric dose of daclizumab is 1 mg/kg intravenously every 14 days for five doses, with the first dose administered within 24 hours pre-transplantation. This administration regimen maintains daclizumab levels necessary to completely saturate the IL-2Ralpha (5-10 microg/mL) in children for at least 12 weeks.The recommended pediatric dose of basiliximab for recipients <35 kg is 10 mg, and 20 mg for recipients > or =35 kg, intravenously on days 0 and 4 post-transplantation. This administration regimen maintains basiliximab levels necessary to completely saturate the IL-2Ralpha (>0.2 microg/mL) in children for at least 3 weeks.

Monitoring of T-cell subsets in patients treated with anti-CD 25 antibody

Daclizumab and basiliximab, the antibodies to the interleukin-2 receptor (anti-IL-2R), decrease the incidence of acute rejection in renal transplantation. However, prolonged blockade of IL-2 receptor (IL-2R:CD25) may hamper apoptosis of reactive T-cell clones and thus may obstruct tolerance induction. We determined the effect of varying doses of anti-IL-2R on the number of CD3+CD25+ cells as an index of CD 25 blockade. The number of CD3+CD25+ cells was determined in four groups of induction therapies: no antibody induction; two doses of 50 or 25 mg daclizumab on day 0 and day 14; and two doses of 20 mg basiliximab at day 0 and day 4 (n=10, 24, 10, and 10, respectively). The number of CD3+CD25+ cells were monitored in whole blood before antibody infusion as well as 24 hours thereafter and weekly after transplantation. With two doses of 50 mg daclizumab, two doses of 25 mg daclizumab, and two doses of 20 mg basiliximab, the expression of CD3+CD25+ cells was completely suppressed for 12, 10, and 12 weeks posttransplantation, respectively. The reappearance of CD3+CD25+ cells above the baseline for each induction regimen was: 17 weeks for two doses of 50 mg daclizumab, 11 weeks for two doses of 25 mg daclizumab, and 13 weeks for two doses of 20 mg basiliximab. Monitoring of CD3+CD25+ cells may be utilized to tailor anti-IL-2R administration at a minimal dosage, yet retaining adequate IL-2R blockade for at least 3 months posttransplantation.

Anti-Interleukin-2 Receptor Antibodies in Transplantation

Two monoclonal antibody preparations against the alpha-chain of the interleukin-2 receptor (IL-2Ralpha) are available for use, basiliximab and daclizumab, a chimeric and a humanised antibody, respectively. The first clinical studies have demonstrated the efficacy of these agents as induction therapy to reduce the rate of acute rejection after organ transplantation. Basiliximab and daclizumab have a similar effect on prevention of acute rejection. Likewise, incidence of infections and malignancies are not different between the two treatment options. Anti-IL-2Ralpha therapy was very well tolerated in clinical trials. Phase III studies with basiliximab have been undertaken with a two-dose regimen, consisting of two doses of 20mg, in an attempt to saturate the IL-2Ralpha on peripheral blood T lymphocytes for an average of 4-6 weeks. In contrast, the daclizumab dose is corrected for bodyweight and the goal is to achieve IL-2Ralpha blockade for 12 weeks. Phase III efficacy trials with daclizumab have, therefore, been developed with five doses of 1 mg/kg every 2 weeks in the first 2 months after transplantation. Whether or not it is a benefit to have blockade of the IL-2Ralpha for 10-12 weeks (daclizumab) compared with 4-6 weeks (basiliximab) remains unknown. Assuming 4-6 weeks would be sufficient for prevention of acute rejection, many centres have changed the protocol of daclizumab administration to two doses, the first dose given at the time of transplantation, the second 10 or 14 days after, with good success. Therefore, it seems feasible to limit the dose of daclizumab, which increases the ease of administration and probably also the cost effectiveness of this agent. There are no controlled studies comparing basiliximab and daclizumab, nor have different dose regimens been directly compared in renal transplantation. The data available suggest the differences are small, if present at all, and it is unlikely that such a trial will ever be done. With both compounds, a significant reduction in the number of acute rejection episodes following solid organ transplantation can be obtained without an increase in adverse effects or infectious complications.

Interleukin 2 receptor antagonists for kidney transplant recipients

BACKGROUND

Interleukin 2 receptor antagonists (IL2Ra) are used as induction therapy for prophylaxis against acute rejection in kidney transplant recipients. Use of IL2Ra has increased steadily, with 38% of new kidney transplant recipients in the United States, and 23% in Australasia receiving IL2Ra in 2002.

OBJECTIVES

This study aims to systematically identify and summarise the effects of using an IL2Ra, as an addition to standard therapy, or as an alternative to other antibody therapy.

SEARCH STRATEGY

The Cochrane Renal Group's specialised register (June 2003), the Cochrane Controlled Trials Register (in The Cochrane Library issue 3, 2002), MEDLINE (1966-November 2002) and EMBASE (1980-November 2002). Reference lists and abstracts of conference proceedings and scientific meetings were hand-searched from 1998-2003. Trial groups, authors of included reports and drug manufacturers were contacted.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing IL2Ra to placebo, no treatment, other IL2Ra or other antibody therapy.

DATA COLLECTION AND ANALYSIS

Data was extracted and quality assessed independently by two reviewers, with differences resolved by discussion. Dichotomous outcomes are reported as relative risk (RR) with 95% confidence intervals (CI).

MAIN RESULTS

One hundred and seventeen reports from 38 trials involving 4893 participants were included. Where IL2Ra were compared with placebo (17 trials; 2786 patients), graft loss was not significantly different at one (RR 0.83, 95% CI 0.66 to 1.04) or three years (RR 0.88, 95% CI 0.64 to 1.22). Acute rejection (AR) was significantly reduced at six months (RR 0.66, 95% CI 0.59 to 0.74) and at one year (RR 0.67, 95% CI 0.60 to 0.75). At one year, cytomegalovirus (CMV) infection (RR 0.82, 95% CI 0.65 to 1.03) and malignancy (RR 0.67, 95% CI 0.33 to 1.36) were not significantly different. Where IL2Ra were compared with other antibody therapy no significant differences in treatment effects were demonstrated, but adverse effects strongly favoured IL2Ra.

REVIEWER'S CONCLUSIONS

Given a 40% risk of rejection, seven patients would need treatment with IL2Ra to prevent one patient having rejection, with no definite improvement in graft or patient survival. There is no apparent difference between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effects

Therapy for acute rejection in pediatric organ transplant recipients

Despite the availability of potent immunosuppressive drugs, rejection after organ transplantation in children remains a serious concern, and may lead to significant morbidity, graft loss, and death of the patient. Acute graft rejection in pediatric recipients is first treated with methylprednisolone pulses, followed by progressive taper of corticosteroid doses. After control of the rejection episode, baseline immunosuppression has to be adjusted and closely monitored since rejection (especially late episodes, occurring more than 6 months after transplantation) may be due to a lack of compliance or sub-therapeutic drug concentrations. The management of corticosteroid resistant rejection is not standardized, and depends on the transplanted organ and previous immunosuppressive regimen. In patients experiencing corticosteroid resistant acute rejection while on a cyclosporine-based immunosuppressive regimen, cyclosporine is generally changed to tacrolimus. In case of tacrolimus-based immunosuppression, tacrolimus blood levels may be increased, and/or mycophenolate mofetil (which nowadays tends to replace azathioprine) or sirolimus may be added, although pharmacodynamic data and clinical studies with these agents are still scarce in pediatric recipients. The use of antithymocyte globulins or monoclonal anti-CD3 antibodies, muromonab CD3 (OKT3) is hampered by numerous adverse effects, including a significant risk of over-immunosuppression. These therapies are nowadays indicated in very selected cases. Other treatments such as plasmapheresis and high dose immunoglobulins may be useful in difficult cases. In patients with refractory rejection despite therapeutic escalation, the risks of over-immunosuppression, including opportunistic infections and malignancies (especially the Epstein-Barr virus related post-transplant lymphoproliferative disease) have to be balanced with the consequences of graft loss due to rejection. Detransplantation or retransplantation may, in some instances, be preferable to severe infectious or tumoral complications.

Analysis of allograft biopsy specimens from long-term surviving patients with stable renal function: predictive value of long-term graft prognosis

Chronic allograft dysfunction is multi-factorial, and histology of long-term renal allograft shows variable findings. It is important to characterize the pathological features of graft kidneys with normal function to understand the natural course of transplants, which in turn would contribute to elucidate the causes of chronic allograft nephropathy (CAN). To address this issue, we performed 'non-episode' biopsies on well-functioning renal allografts, and evaluated the correlation between clinical outcome and histopathological findings. Patients who underwent a non-episode biopsy had a serum creatinine concentration less than 2.0 mg/dL, urinary protein of less than 500 mg/day and a stable clinical course. In total, 90 such biopsies were performed. Mean follow-up period after biopsy was 29 +/- 16 months. We evaluated the histopathological findings and clinical outcome on each finding. Moreover, we compared the findings in the patients on tacrolimus with those of patients taking cyclosporin. Twenty-three biopsy specimens were essentially normal. Graft dysfunction during the follow-up period was recognized more frequently in patients showing more than one pathological process than in those with isolated findings. Graft outcome was not associated with drug-induced nephropathy, but with acute rejection (P = 0.0193) and CAN (P = 0.0032). Patients found to have CAN-b had a worse outcome than those with CAN-a. CAN-b was less common in the tacrolimus group than in the cyclosporin group. Non-episode biopsy has a predictive value of the long-term outcome of a renal allograft. CAN is associated with graft dysfunction; neither is drug-induced nephropathy. Patients treated with tacrolimus had lower rates of CAN-b than did cyclosporin-treated subjects.

Blockade of intragraft IL-2 receptor-alpha by basiliximab is insufficient to prevent activation of liver graft infiltrating cells

Treatment with basiliximab, a CD25 (Interleukin-2 receptor-alpha; IL-2Ralpha)-blocking human-murine chimeric antibody, reduces the incidence of acute rejections after organ transplantation, but rejection is not completely prevented. We investigated whether rejections during basiliximab treatment were due to insufficient exposure to the antibody or to incomplete blockade of intragraft CD25, and whether CD25-blockade affected activation of liver transplant infiltrating cells. Twenty-seven basiliximab-treated liver transplant recipients and seven patients not treated with basiliximab, from which post-transplant liver biopsies were available, were retrospectively selected for this study. Rejectors among the basiliximab-treated patients (n=11) had not cleared basiliximab from their blood at a faster rate than non-rejectors (n=16). Rejections within the period of saturating serum basiliximab concentrations were in most cases not due to insufficient intragraft CD25-blockade: in eight out of eleven rejection biopsies obtained during this period CD25 on graft-infiltrating cells was completely coated by basiliximab. Despite CD25 blockade, portal infiltrates in these biopsies showed similar expression of the proliferation-associated antigen Ki-67 and of the cytotoxic effector molecules granzyme A and B as those in rejection biopsies obtained from patients not treated with basiliximab. In conclusion, basiliximab treatment of liver transplant patients results in blockade of intragraft CD25, but nevertheless cells in rejection infiltrates are strongly activated, probably by a mechanism bypassing the IL-2Ralpha.

Basiliximab

Basiliximab (Simulect), a chimeric (human/murine) monoclonal antibody, is indicated for the prevention of acute organ rejection in adult and paediatric renal transplant recipients in combination with other immunosuppressive agents. Basiliximab significantly reduced acute rejection compared with placebo in renal transplant recipients receiving dual- (cyclosporin microemulsion and corticosteroids) or triple-immunotherapy (azathioprine- or mycophenolate mofetil-based); graft and patient survival rates at 12 months were similar. Significantly more basiliximab than placebo recipients were free from the combined endpoint of death, graft loss or acute rejection 3 years, but not 5 years, after transplantation. The incidence of adverse events was similar in basiliximab and placebo recipients, with no increase in the incidence of infection, including cytomegalovirus (CMV) infection. Malignancies or post-transplant lymphoproliferative disorders after treatment with basiliximab were rare, with a similar incidence to that seen with placebo at 12 months or 5 years post-transplantation. Rare cases of hypersensitivity reactions to basiliximab have been reported. The efficacy of basiliximab was similar to that of equine antithymocyte globulin (ATG) and daclizumab, and similar to or greater than that of muromonab CD3. Basiliximab was as effective as rabbit antithymocyte globulin (RATG) in patients at relatively low risk of acute rejection, but less effective in high-risk patients. Numerically or significantly fewer patients receiving basiliximab experienced adverse events considered to be related to the study drug than ATG or RATG recipients. The incidence of infection, including CMV infection, was similar with basiliximab and ATG or RATG. Basiliximab plus baseline immunosuppression resulted in no significant differences in acute rejection rates compared with baseline immunosuppression with or without ATG or antilymphocyte globulin in retrospective analyses conducted for small numbers of paediatric patients. Limited data from paediatric renal transplant recipients suggest a similar tolerability profile to that in adults. Basiliximab appears to allow the withdrawal of corticosteroids or the use of corticosteroid-free or calcineurin inhibitor-sparing regimens in renal transplant recipients. Basiliximab did not increase the overall costs of therapy in pharmacoeconomic studies.

CONCLUSION

Basiliximab reduces acute rejection without increasing the incidence of adverse events, including infection and malignancy, in renal transplant recipients when combined with standard dual- or triple-immunotherapy. The overall incidence of death, graft loss or acute rejection was significantly reduced at 3 years; there was no significant difference for this endpoint 5 years after transplantation. Malignancy was not increased at 5 years. The overall efficacy, tolerability, ease of administration and cost effectiveness of basiliximab make it an attractive option for the prophylaxis of acute renal transplant rejection.

A rational dosing algorithm for basiliximab (Simulect) in pediatric renal transplantation based on pharmacokinetic-dynamic evaluations

BACKGROUND

The pharmacokinetics and immunodynamics of basiliximab were assessed in 39 pediatric de novo kidney allograft recipients to rationally chose a dose regimen for this age group.

METHODS

In study part 1, patients were given 12 mg/m(2) of basiliximab by bolus intravenous injection before surgery and on day 4. An interim pharmacokinetic evaluation supported a fixed-dose approach for study part 2 in which infants and children received two 10-mg doses and adolescents received two 20-mg doses. Blood samples were collected over a 12-week period for analysis of basiliximab and soluble interleukin-2 receptor concentrations, flow cytometry, and screening for anti-idiotype antibodies.

RESULTS

Basiliximab clearance in infants and children (n=25) was reduced by approximately half compared with adults from a previous study and was independent of age (1-11 years), weight (9-37 kg), and body surface area (0.44-1.20 m(2) ). Clearance in adolescents (12-16 years, n=14) approached or reached adult values. CD25-saturating basiliximab concentrations were maintained for 31+/-12 days in study part 1 with mg/m(2) dosing and for 36+/-14 days in study part 2 based on the fixed-dose regimen ( P=0.31). A single patient experienced a rejection episode during CD25 saturation. The duration of CD25 saturation in patients who experienced a rejection episode after desaturation did not differ from those who remained rejection-free for the full 6-month period: 34+/-6 days (n=6) vs. 35+/-14 days (n=33 patients); P=0.74. Anti-idiotype antibodies were detected in two patients; however, this did not influence the clearance of basiliximab or the duration of CD25 saturation.

CONCLUSIONS

To achieve similar basiliximab exposure as is efficacious in adults, pediatric patients <35 kg should receive two 10-mg doses and those > or =35 kg should receive two 20-mg doses of basiliximab by intravenous infusion or bolus injection. The first dose is given before surgery and the second on day 4 after transplantation.

Immunosuppressive therapy for paediatric transplant patients: pharmacokinetic considerations

Immunosuppressive therapy in paediatric transplant recipients is changing as a consequence of the increasing number of available immunosuppressive agents. Generic and other new formulations are now emerging onto the market, clinical experience is growing, and it is expected that clinicians should tailor immunosuppressive protocols to individual patients by optimising dosages and drugs according to the maturation and clinical status of the child. Most information about the clinical pharmacokinetics of immunosuppressive drugs in paediatrics is centred on cyclosporin, tacrolimus and mycophenolate mofetil in renal and liver transplant recipients; data regarding other immunosuppressants and transplant types are limited. Although the clinical pharmacokinetics of these drugs in paediatric transplant recipients are still under investigation, it is evident that the pharmacokinetic parameters observed in adults may not be applicable to children, especially in younger age groups. In general, patients younger than 5 years old show higher clearance rates irrespective of the organ transplanted or drug used. Another important factor that frequently affects clearance in this patient population is the post-transplant time. In accordance with these findings, and in contrast with the usual under-dosage in children, the need for higher dosages in younger recipients and during the early post-transplant period seems evident. To achieve the best compromise between prevention of rejection and toxicity, dosage individualisation is required and this can be achieved through therapeutic drug monitoring (TDM). This approach is particularly useful to ensure the cost-effective management of paediatric transplant recipients in whom the pharmacokinetic behaviour, target concentrations for clinical use and optimal dosage strategies of a particular drug may not yet be well defined. Although TDM may be a tool for improving immunosuppressive therapy, there is little information concerning its positive contribution to clinical events, including outcomes, for paediatric patients. Substantial information to support the use of TDM exists for cyclosporin and, to a lesser extent, for tacrolimus, but a diversity of options affects their implementation in the clinical setting. The role of TDM in therapy with mycophenolate mofetil and sirolimus has yet to be defined regarding both methods and clinical indications. Pharmacodynamic monitoring appears more suited to other immunosuppressants such as azathioprine, corticosteroids and monoclonal or polyclonal antibodies. If coupled with pharmacokinetic measurements, such monitoring would allow earlier and more precise optimisation of therapy. Very few population pharmacokinetic studies have been carried out in paediatric transplant patients. This type of study is needed so that techniques such as Bayesian forecasting can be applied to optimise immunosuppressive therapy in paediatric transplant patients.

Concomitant basiliximab with low-dose calcineurin inhibitors in children post-liver transplantation

Orthotopic liver transplantation (OLT) is effective therapy for end-stage liver disease but immunosuppression with calcineurin inhibitors (CNI) leads to significant nephrotoxicity, resulting in either a reduction of dosage to below the therapeutic level or omission of the drug altogether. Basiliximab (Bx) is a human/mouse chimeric monoclonal antibody that inhibits binding of interleukin-2 (IL-2) to IL-2 receptors and thus prevents proliferation of T cells, which is the main step in the development of acute cellular rejection. The aim of this study was to identify the role of Bx in the prevention of acute cellular rejection and in the reduction of nephrotoxicity in children post-liver transplantation. We evaluated three children (19 months, 22 months, and 11 yr of age; one male, two female) who were treated with Bx post-OLT on compassionate grounds. The indications were: nephrotoxicity in two children, requiring re-transplantation for hepatic artery thrombosis and recurrent giant cell hepatitis, respectively; and nephrotoxicity secondary to chemotherapy for hepatoblastoma in the third child. All patients received 10 mg of Bx, at OLT and on Day 4. Tacrolimus (0.15 mg/kg/day) was started at 48 h (n = 2) and cyclosporin (5 mg/kg/day) at 2 weeks (n = 1). Trough levels of tacrolimus were maintained at 5-8 ng/mL and trough levels of cyclosporin at 100-150 mg/L for the first 3 months. All patients received methylprednisolone (2 mg/kg) with azathioprine (1.5 mg/kg) (n = 2) and/or mycophenolate mofetil (20 mg/kg) (n = 1). The glomerular filtration rate (cGFR) was calculated using the Schwartz formula before and 10 weeks after transplant. Bx was found to be easy to administer and no major side-effects were reported. One child had two episodes of mild acute rejection at 5 and 9 weeks post-OLT and one developed chronic rejection requiring re-transplantation at 9 weeks post-OLT. One child did not develop rejection. The mean pretransplant cGFR was 58.1 (54.6-64.1) mL/min/m2. Within 10 weeks of transplantation, the cGFR had improved by 69% to a mean of 116 (88-157.6) mL/min/m2. To conclude, Bx was well tolerated in all children and had a renal sparing effect. It was effective in preventing early acute rejection, but the combination of Bx and low-dose CNI drugs did not prevent late acute or chronic rejection. Further studies to evaluate the appropriate levels of CNI immunosuppression with Bx are required.

Pharmacokinetics, pharmacodynamics, and immunodynamics of daclizumab in a two-dose regimen in liver transplantation

BACKGROUND

The humanized anti-interleukin 2 receptor (IL-2R) monoclonal antibody daclizumab (Zenapax) has been shown to be safe and effective for preventing acute allograft rejection in renal transplantation. The aim of this study was to evaluate pharmacokinetics and pharmacodynamics of daclizumab in a two-dose regimen (1.5 mg/kg total) after liver transplantation.

METHODS

Twenty-eight patients were enrolled in this study. Patients were evaluated for outcome, postoperative blood and ascites loss, serum levels of daclizumab, and corresponding changes in peripheral blood. Patients were also checked for development of anti-daclizumab antibodies.

RESULTS

CD25+ cells in patients' blood were significantly reduced for 28 days after daclizumab application. Elimination half-life of the antibody was 99 hr with a total body clearance of 57 ml/hr. Blood loss was not statistically significant and loss of ascites was weakly correlated to the monoclonal antibody clearance. One episode of mild acute rejection occurred. Although there was no significant decrease in absolute counts of CD3+, CD4+, and CD8+ lymphocytes, we were not able to show constant coating of IL-2Ralpha with daclizumab. IL-2Ralpha was not detectable on cell surface with two different antibodies and IL-2Rbeta was clearly reduced. Low titers of neutralizing anti-daclizumab antibodies in 3 of 13 patients were not of clinical significance and without influence on the pharmacokinetics.

CONCLUSIONS

A two-dose regimen with daclizumab in liver transplantation leads to effective blockade of the IL-2Ralpha for at least 14 days after transplantation. Daclizumab seems to affect not only IL-2Ralpha but also IL-2Rbeta and may lead to an impairment of other cytokine pathways, such as the IL-15 pathway.

Anti-CD25 monoclonal antibody coverage allows for calcineurin inhibitor "holiday" in solid organ transplant patients with acute renal dysfunction

BACKGROUND

Solid organ transplant (Tx) patients on calcineurin inhibitors (CNI) can develop acute renal dysfunction (ARD), which could be improved by reducing or withholding ("holiday") CNI dose.

METHODS

We used anti-CD25 monoclonal antibodies to prevent acute rejection in 11 adult Tx patients (7 heart, 2 liver, 2 heart-renal Tx), requiring a CNI "holiday" because of 15 events of ARD after the initial postTx hospitalization. An event of ARD was defined as an increase in serum creatinine (Scr)>25% vs. baseline. The CNI "holiday" was implemented until Scr had decreased to baseline. Basiliximab was used in 7 patients (11 events), and daclizumab was used in 4 patients (4 events).

RESULTS

The CNI "holiday" was implemented over 21+/-51 days. Anti-CD25 mAb were well tolerated with no episodes of acute rejection. Scr (micromol/liter) increased from 145+/-48 to 301+/-92 (P<0.0001), and decreased to 143+/-55 with the CNI "holiday."

CONCLUSIONS

Our results suggest that a CNI "holiday" may improve ARD after solid organ Tx without rejection under anti-CD25 mAb coverage.

Down regulation of B cells by immunization with a fusion protein of a self CD20 peptide and a foreign IgG.Fc fragment

In vivo studies of mice were performed to investigate whether auto-reactive antibodies specific for self CD20 antigen on B cells could be induced by immunizing with a CD20 peptide linked to a foreign, human IgG.Fc fragment through a T cell immunologically inert linker peptide and how such an auto-reactivity, if generated, would affect the levels of B cells. The dimeric Fc fusion protein containing the extracellular 44-amino acid portion of CD20, and the CH2-CH3 domains of human gamma 1 immunoglobulin were prepared. After several subcutaneous immunizations with this CD20-Fc protein, mice produced anti-CD20 antibodies that can bind to native CD20 on normal B cells and B-lymphoma cells. In mice immunized with the CD20-Fc protein, the fraction of B cells in total peripheral blood lymphocytes decreased to about 40%, significantly lower than that of mice immunized with human IgG. In addition, antibody response towards an irrelevant bystander antigen, chicken ovalbumin, was weakened compared with that of mice immunized with human IgG. These results show that auto-reactive antibodies specific for CD20 can be induced by immunizing with an autologous CD20 peptide fused with a foreign IgG.Fc and that the auto-antibodies can partially reduce the levels of B cells and their response to other antigens.

Single centre experience with basiliximab in paediatric renal transplantation

BACKGROUND

Introduction of IL-2-receptor antagonists has led to significantly decreasing numbers of acute rejection episodes in renal transplantation in adults. No data are available in paediatric recipients.

METHODS

Between 1997 and 2000, 78 renal transplantations were performed in 77 children aged 0.5-16 years. Basiliximab, cyclosporin A (CsA) and prednisolone were administered in 48 children (age 7.8 +/- 5.3 years) and compared with 29 children (age 7.3 +/- 5.2 years) receiving CsA and prednisolone only. The number of acute rejections, survival, glomerular filtration rate (GFR) and side effects were determined for 3 years after transplantation.

RESULTS

All 77 patients survived the observation period. One year graft survival in the basiliximab group was 95%, which is similar to the comparison group (93%). Children receiving basiliximab showed a lower incidence of acute rejection than the comparison group (14% vs 34%). The calculated GFR was lower in the basiliximab group when discharging from hospital, with 51 compared with 66 ml/min/1.73 m(2) in the non-basiliximab group. This was associated with higher CsA trough levels (214 vs 174 ng/ml) in the basiliximab patients. After 1 year the GFR was comparable in both groups (58 vs 52 ml/min/1.73 m(2)).

CONCLUSIONS

Basiliximab offers excellent allograft survival, a lower incidence of acute rejections and almost no side effects. Therefore it can be recommended for routine immunosuppressive therapy in paediatric renal transplantation.

Role of anti-interleukin-2 receptor antibodies in kidney transplantation

From the early 1960s, the mainstay of immunosuppression for kidney transplantation has been corticosteroids. Since then, many new drugs have been developed to maintain the renal allograft. Current maintenance immunosuppression commonly consists of corticosteroids, antiproliferative agents and calcineurin inhibitors (e.g. cyclosporin). More recently, antihuman antibodies, either monoclonal or polyclonal, have been developed to use for induction at the time of transplantation or to treat rejection. With the advances in molecular technology, a new class of antihuman antibodies [the anti-interleukin-2 receptor (IL-2R) antibodies] has emerged that incorporate a murine antigen-binding site on to a human immunoglobulin backbone. Such methodology creates antihuman antibodies with high affinity for the epitope and with prolonged serum antibody half-lives. Interleukin-2 and its receptor are central to lymphocyte activation and are the main targets of calcineurin inhibitors. In addition, the anti-IL-2R antibodies inhibit a key target in immune activation. Daclizumab and basiliximab have been shown to significantly reduce the incidence of acute rejection in kidney transplantation. Since these anti-IL-2R antibodies are well tolerated and since calcineurin inhibitors are intrinsically nephrotoxic, anti-IL-2R antibodies have been used in an attempt to avoid cyclosporin after transplantation. Data from clinical trials seem to indicate that the addition of an anti-IL-2R antibody is not sufficient to warrant complete withdrawal of calcineurin inhibitors for more than a very short period after transplantation. A more promising role for anti-IL-2R antibodies may be in renal transplant recipients with delayed graft function (DGF). Recent data on the use of either low-dose calcineurin inhibitors or sirolimus (rapamycin) in conjunction with the anti-IL-2R antibodies for patients with DGF showed no increased risk of acute rejection. Long-term graft survival with use of these low-dose calcineurin inhibitor protocols has yet to be established.