Screening for basiliximab exposure-response relationships in renal allotransplantation

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.

Renal function after liver transplantation: Real-world experience with basiliximab induction and delayed reduced-dose tacrolimus

BACKGROUND

Routine use of delayed reduced-dose calcineurin-inhibitor treatment with induction immunosuppression in liver transplantation to minimize post-operative kidney injury is still scarce.

AIM

To evaluate real-world experience of basiliximab induction with delayed reduced-dose tacrolimus.

METHODS

In a retrospective cohort study, kidney function was evaluated pre- and postoperatively by measured glomerular filtration rate (mGFR). Adult patients undergoing liver transplantation between 2000 and 2017 were divided into a conventional treatment group (immediate-introduction of tacrolimus, target trough levels 10-15 ng/mL, and corticosteroids, n = 203) and a revised treatment group (basiliximab induction, reduced-dose tacrolimus, target through levels 5-8 ng/mL, delayed until day three, and mycophenolate mofetil 2000 mg/day, n = 343).

RESULTS

Mean mGFR was similar between groups at wait-listing (85.3 vs 84.1 ml/min/1.73m², p = 0.60), but higher in the revised treatment group at 3 (56.8 vs 63.4 ml/min/1.73m², p = 0.004) and 12 months post-transplant (60.9 vs 69.7 ml/min/1.73m², p<0.001); this difference remained after correcting for multiple confounders and was independent of pre-transplant mGFR. In the revised treatment group, biopsy proven acute rejection rate was lower (38% vs. 21%, p<0.001), and graft-survival better (p = 0.01).

CONCLUSION

Basiliximab induction with delayed reduced-dose tacrolimus is associated with less kidney injury when compared to standard-dose tacrolimus, without increased risk of rejection, graft loss or death.

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.

Renal function three years after early conversion from a calcineurin inhibitor to everolimus: results from a randomized trial in kidney transplantation

In a 36-month, open-label, multicenter trial, 202 kidney transplant recipients were randomized at week 7 post-transplant to convert to everolimus or remain on cyclosporine: 182 were analyzed to month 36 (92 everolimus, 90 controls). Mean (SD) change in measured GFR (mGFR) from randomization to month 36 was 1.3 (14.0) ml/min with everolimus versus -1.7 (15.4) ml/min in controls (P = 0.210). In patients who remained on treatment, mean mGFR improved from randomization to month 36 by 7.9 (11.5) ml/min with everolimus (n = 37) but decreased by 1.4 (14.7) ml/min in controls (n = 62) (P = 0.001). During months 12-36, death-censored graft survival was 100%, patient survival was 98.9% and 96.7% in the everolimus and control groups, respectively, and 13.0% and 11.1% of everolimus and control patients, respectively, experienced mild biopsy-proven acute rejection (BPAR). Protocol biopsies in a limited number of on-treatment patients showed similar interstitial fibrosis progression. Donor-specific antibodies were present at month 36 in 6.3% (2/32) and 18.0% (9/50) of on-treatment everolimus and control patients with available data (P = 0.281). During months 12-36, adverse events were comparable, but discontinuation was more frequent with everolimus (33.7% vs. 10.0%). Conversion from cyclosporine to everolimus at 7 weeks post-transplant was associated with a significant benefit in renal function at 3 years when everolimus was continued.

Induction immunosuppression in liver transplantation: a review

Antibody therapy for induction is seldom used in liver transplantation in the United States, but continues to be used in approximately 10% of patients. The most commonly used antibody at the current time is basiliximab (Simulect, Novartis) and is used in adults with renal dysfunction at the time of liver transplantation with the intention of delaying introduction of calcineurin-inhibitors. In children, the same antibody is commonly used in order to reduce rates of acute rejection. Most patients, adult and pediatric, are treated with initially higher levels of tacrolimus rather than antibody induction.

Review article: use of induction therapy in liver transplantation

Induction therapy is used relatively infrequently in liver transplantation, but developments in induction regimens and strategies for their use are prompting a re-examination of its benefits. Rabbit antithymocyte globulin (rATG) induces protracted, dose-dependent lymphocytopenia with preferential reconstitution of regulatory T-lymphocytes. Non-depleting interleukin-2 receptor antagonists (IL-2RA) act selectively on activated T-lymphocytes with a shorter duration of effect. IL-2RA induction with delayed and reduced calcineurin inhibitor (CNI) exposure appears to preserve efficacy, while more aggressive CNI minimisation has been attempted successfully using rATG. Steroid-free tacrolimus monotherapy with rATG or IL-2RA induction is effective if adequate tacrolimus exposure is maintained. Early concerns that addition of induction to a conventional maintenance regimen could lead to accelerated progression of hepatitis C disease, or to an increased risk of hepatocellular cancer recurrence, now appear unfounded using modern regimens. Similarly, with routine use of systemic prophylaxis, recent prospective and retrospective data have not shown a higher rate of infections overall, or cytomegalovirus infection specifically, using rATG or IL-2RA induction. Historical evidence that lymphocyte-depleting agents increased the risk of non-Hodgkin lymphoma has not been confirmed for rATG. Wider use of induction in liver transplantation is now merited, using individualized strategies to support reduced CNI exposure or steroid-free immunosuppression.

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.

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.

CD4+ regulatory cells as a potential immunotherapy

CD4(+) regulatory T (T(R)) cells represent a unique lineage of thymically generated lymphocytes capable of powerfully suppressing immune responses. A large body of experimental data has now confirmed the key role played by these cells in the maintenance of self-tolerance. Increasingly, the importance of these cells is also being recognized in a host of other clinically relevant areas such as transplantation, tumour immunity, allergy and microbial immunity. Additionally, it is also possible to generate T(R) cells by using a variety of ex vivo experimental approaches. We will focus here on harnessing the suppressive abilities of both these families of regulatory cells and how this should give us access to a potent cell-based immunotherapy appropriate for clinical application.

Pharmacokinetics and concentration–effect relationships of therapeutic monoclonal antibodies and fusion proteins

Although monoclonal antibodies (mAbs) constitute a major advance in therapeutics, their pharmacokinetic (PK) and pharmacodynamic (PD) properties are not fully understood. Saturable mechanisms are thought to occur in distribution and elimination of mAbs, which are protected from degradation by the Brambell's receptor (FcRn). The binding of mAbs to their target antigen explains part of their nonlinear PK and PD properties. The interindividual variability in mAb PK can be explained by several factors, including immune response against the biodrug and differences in the number of antigenic sites. The concentration-effect relationships of mAbs are complex and dependent on their mechanism of action. Interindividual differences in mAb PD can be explained by factors such as genetics and clinical status. PK and concentration-effect studies are necessary to design optimal dosing regimens. Because of their above-mentioned characteristics, the interindividual variability in their dose-response relationships must be studied by PK-PD modelling.

Interleukin-2 receptor antagonists and aggressive steroid minimization strategies for kidney transplant patients

Steroid withdrawal during the first week after transplantation surgery, or complete avoidance of steroids, offers potential benefits. The interleukin-2 (IL-2) receptor antibodies, basiliximab and daclizumab, can enable aggressive steroid minimization protocols that are efficacious while reducing toxicity. A multicenter, randomized trial of kidney transplant recipients has shown the incidence of biopsy-proven acute rejection with basiliximab, cyclosporine and mycophenolate mofetil with steroids withdrawn at day 5 to be similar to a conventional triple-therapy regimen. A single perioperative dose of corticosteroids with an IL-2 receptor antagonist also seems as efficacious as standard steroid therapy. Corticosteroid-minimization with IL-2 receptor antagonists has also been investigated with sirolimus-containing regimens and has shown excellent outcomes. Experience with complete steroid avoidance, using an IL-2 receptor antagonist, is limited, but initial results are promising, particularly in pediatric patients. Administration of an IL-2 receptor antagonist with aggressive steroid minimization in selected, well-monitored patients seems reasonable, but further trials are required to define optimal protocols.

Interleukin-2 receptor antagonists and aggressive steroid minimization strategies for kidney transplant patients

Steroid withdrawal during the first week after transplantation surgery, or complete avoidance of steroids, offers potential benefits. The interleukin-2 (IL-2) receptor antibodies, basiliximab and daclizumab, can enable aggressive steroid minimization protocols that are efficacious while reducing toxicity. A multicenter, randomized trial of kidney transplant recipients has shown the incidence of biopsy-proven acute rejection with basiliximab, cyclosporine and mycophenolate mofetil with steroids withdrawn at day 5 to be similar to a conventional triple-therapy regimen. A single perioperative dose of corticosteroids with an IL-2 receptor antagonist also seems as efficacious as standard steroid therapy. Corticosteroid-minimization with IL-2 receptor antagonists has also been investigated with sirolimus-containing regimens and has shown excellent outcomes. Experience with complete steroid avoidance, using an IL-2 receptor antagonist, is limited, but initial results are promising, particularly in pediatric patients. Administration of an IL-2 receptor antagonist with aggressive steroid minimization in selected, well-monitored patients seems reasonable, but further trials are required to define optimal protocols.

Meta-analysis of basiliximab for immunoprophylaxis in renal transplantation

BACKGROUND

Basiliximab is a high-affinity chimeric monoclonal antibody directed against the alpha-chain of the interleukin (IL)-2 receptor. Individual studies have shown that it is highly effective in preventing acute rejection and causes no measurable incremental toxicity. However, incorporation of basiliximab immunoprophylaxis into routine practice depends upon the demonstration of benefit across treatment regimens and quantitation of the treatment effect.

METHODS

This study employed a meta-analysis to examine the clinical benefit of basiliximab. Parameter estimates were derived from four randomised prospective double-blind studies conducted in 93 renal transplant centres in 18 countries. A total of 1185 adult primary allograft recipients were randomised within the centres to receive either basiliximab 20mg intravenously on days 0 and 4 or placebo, in addition to double or triple immunosuppression consisting of cyclosporin-microemulsion (Neoral((R))The use of tradenames is for product identification purposes only and does not imply endorsement.), corticosteroids, and azathioprine or mycophenolate mofetil. Key clinical events included patient and graft survival, graft rejection and complications. Analysis was performed using a variable model; odds ratios and the numbers needed to treat (NNT) to benefit or to harm one patient were calculated for each principal outcome at 6 or 12 months post-transplant.

RESULTS

Basiliximab reduced the relative risk (RR) and absolute risk (AR) of clinical and biopsy-proven acute graft rejection across all treatment regimens. The overall RR of clinical acute graft rejection was decreased by 35% in patients receiving basiliximab. AR was reduced by 15.6% (pooled incidence: 28.8% vs 44.4%, p < 0.0001), and the NNT for efficacy was six. The reduction in RR of biopsy-proven rejection was similar (32%) with an absolute risk reduction (ARR) of 11.7% (pooled incidence: 25.1% vs 36.8%, p < 0.0001) and NNT of nine over 6 months. There was a concomitant reduction in the risk of graft loss which did not reach statistical significance (p = 0.14). The RR of graft loss was reduced by 26% with an AR reduction of 2.3% (pooled incidence: 6.4% vs 8.7%) and an NNT of 42 over 6 months. The risk of death was unchanged.

CONCLUSIONS

Immunoprophylaxis with basiliximab produces a significant reduction in the RR and AR of clinical and biopsy-proven acute graft rejection with a trend towards a concomitant reduction in the risk of graft loss. The magnitude of protection provided by basiliximab, the fact that it is observed across treatment regimens and the safety of this therapy are arguments for its routine use in renal transplantation.

Basiliximab in association with tacrolimus and steroids in caucasian cadaveric renal transplanted patients: significant decrease in early acute rejection rate and hospitalization time

Safety and tolerability of basiliximab in renal transplantation have been proven in different immunosuppressive regimens. Few informations are available about the association of basiliximab with tacrolimus and steroids. We present a retrospective analysis performed in Caucasian cadaveric renal transplant recipients, comparing a basiliximab, tacrolimus and steroids induction protocol (GrA: 51 patients) with a tacrolimus and steroids protocol (GrB: 46 patients). A significant decrease in acute rejection rate in the first 3 months (2.0% vs. 17.4%; p < 0.01) was noted. Interestingly, the recipients in GrA were at major immunologic risk for the younger age of recipients, the greater number of mismatches and the higher rate of second transplants. The hospitalization times resulted reduced of 5.3 d in GrA vs. GrB (20.8 d vs. 26.1 d; p < 0.05). The adverse events patterns and profiles were similar in the two treatments groups. One patient in each group had a post-transplant lymphoprolipherative disorder. No significant difference was found in patient and graft survival. According to the results of this study, in a Caucasian adult population, basiliximab in association with tacrolimus and steroids is a safe and efficacious tool for acute rejection prevention and it is cost saving by reducing the hospitalization times.

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

Multicenter randomized prospective trial of steroid withdrawal in renal transplant recipients receiving basiliximab, cyclosporine microemulsion and mycophenolate mofetil

Corticosteroids withdrawal from immunosuppressive regimens has thus far been associated with increased risk of acute rejection episodes. In this study, basiliximab, a chimeric monoclonal interleukin-2 receptor antagonist, added to a maintenance regimen consisting of cyclosporine microemulsion and mycophenolate mofetil was studied for its effectiveness in allowing early corticosteroid withdrawal in de novo renal allograft recipients. Primary renal transplant recipients receiving basiliximab, cyclosporine-microemulsion, and mycophenolate mofetil, were randomized to either corticosteroid withdrawal at day four post-transplantation (n = 40) or standard steroid therapy (n = 43). The primary endpoint was the incidence of biopsy-proven acute rejection episodes. Randomized subjects who underwent transplantation and received at least one dose of basiliximab were analyzed in an intent-to-treat fashion. The incidence of biopsy-proven acute rejection at 12 months was not significantly different between the steroid withdrawal group (20%) and the standard treatment group (16%). Patient and graft survival was 100% in the steroid withdrawal group while one death in a patient with a functioning graft occurred in the standard steroid group. Seventy-two percent of the steroid withdrawal group remained off steroids at 6 months post-transplant. Allograft function and incidence of adverse events and infections were similar between the two groups. Rapid and early corticosteroid withdrawal among renal transplant recipients receiving basiliximab induction and daily therapy with cyclosporine-microemulsion and mycophenolate mofetil was not associated with an increased risk of acute rejection.

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.

Pharmacokinetics of CAMPATH-1H in BMT patients

BACKGROUND

CAMPATH-1 (CD52)Abs are used in stem-cell transplantation for prevention of GvHD and rejection. The humanized Ab CAMPATH1H has recently replaced the rat Ab CAMPATH-1G. There was a concern whether it might have a longer half-life in vivo and, possibly, cause prolonged immunosuppression post-transplant.

METHODS

Serum samples were collected pre- and post-transplant from patients receiving CAMPATH-1H at 10 mg/day according to two protocols: (A) from Day -5 to Day +4 (total dose, 100 mg), (B) from Day -10 to Day -6 (total dose, 50 mg). The Ab concentrations were measured using an immunofluorescence assay.

RESULTS

Lymphocytes were substantially depleted by the second day of treatment and were below 0.1 x 10(9)/L by the day of transplant and for at least 1 month post-transplant. By Day 90 there was a greater recovery in Group B, to a median of 0.32 x 10(9)/L compared with 0.25 x 10(9)/L in Group A. By Day 180, both groups had recovered to approx 0.52 x 10(9)/L. Serum concentrations of CAMPATH-1H on the day of transplant were well above the level necessary for opsonization of lymphocytes. The peak Ab concentration was 6.1 micro g/mL in Group A and 2.5 micro g/mL in Group B. CAMPATH-1H could be detected in Group A for 23 days post-transplant, significantly longer than in Group B (11 days). The terminal half-life in the two groups was similar (range 15-21 days) and contrasts with the half-life of < 1 day previously estimated for CAMPATH-1G. There were no cases of graft failure and the incidence of GvHD was similar in the two groups.

DISCUSSION

The humanized Ab CAMPATH-1H appears to persist in the circulation for longer than the original rat Ab CAMPATH-1G. This might contribute to delayed lymphocyte recovery and prohibit the use of early donor-lymphocyte infusions. A short course of treatment given early pre-transplant is likely to be preferable to the extended course given both pre- and post-transplant.

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.

Inhibition of the IL-15 pathway in anti-CD25 mAb treated renal allograft recipients

Anti-CD25 mAb's are used for prophylaxis of rejection in allograft transplantation. These agents target the alpha-chain, part of the IL-2Ralphabetagamma complex. The beta- and gamma-chain are signaling components that are not specific for IL-2. The T-cell growth factors IL2, IL-7 and IL-15 utilize the gamma-chain and IL-2 and IL-15 share the beta-chain. We have studied the consequences of targeting the IL-2R alpha-chain with the anti-CD25 mAb basiliximab by measuring the IL-2R alphabetagamma expression levels and the IL-2, IL-7 and IL-15 driven proliferation. By flowcytometry and limiting dilution analysis, the IL-2R complex was analyzed in peripheral blood samples from renal allograft recipients (n = 29) who received basiliximab (20 mg IV bolus on day 0 and 4), cyclosporin and mycophenolate mofetil. In peripheral blood, after induction therapy with basiliximab, no CD25 positive T-cells were detectable for 61 days (median, range 25-93 days). When CD25 cells were covered with basiliximab, the percentage and the mean fluorescence intensity (MFI) of IL-2Rbeta positive T-cells significantly decreased, P = 0.02 and P = 0.013, respectively, whereas the expression level of the IL-2Rgamma was not affected. The inhibition of the expression of the IL-2R alpha- and beta-chain had significant consequences for the function of these cells. Both the IL-2- and the IL-15-dependent proliferation were inhibited, P = 0.007 and P = 0.01, respectively. The control, the IL-7 driven proliferation, was not influenced by basiliximab. In conclusion, therapy with anti-CD25 mAb's affect T-cell-dependent allogeneic immune responses, not only by blocking IL-2 signaling but also by impairing IL-15 signaling through downregulating the IL-2/IL-15 receptor beta-chain.

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.

Efficacy and tolerability of interleukin-2 receptor blockade with basiliximab in pediatric renal transplant recipients

Rejection remains a major threat in pediatric renal transplantation (Tx), causing graft failure and increased exposure to drugs. The new chimeric antibody, basiliximab, directed against the alpha-chain of the interleukin-2 receptor (IL-2R), has been shown to be effective in preventing rejection episodes in adult renal transplant recipients. In our single-center experience from Essen, Germany, we evaluated prospectively the efficacy and tolerability of basiliximab, in combination with cyclosporin A (CsA) and prednisone, in 38 unselected pediatric patients. Mean patient age at Tx was 10.1 yr. Twenty-eight children received a cadaveric organ and 10 children received living-related donor grafts. The 1-yr patient survival rate was 100% and the 1-yr graft survival rate was 95% (36/38 patients). No graft was lost as a result of immunological factors, and single rejection episodes were observed in eight patients (21%). Two of these rejections were steroid-resistant and responded to tacrolimus rescue therapy. The rate of infections was not enhanced; overt cytomegalovirus (CMV) disease was observed in two patients only. Malignancies have not been seen to date. The blockade of the alpha-chain of the IL-2R lasted for up to 6 weeks. We conclude that the addition of basiliximab to standard immunosuppression in pediatric renal transplant recipients is well tolerated and results in a low incidence of rejection. The simple mode of application and the lack of side-effects make basiliximab an especially useful adjunct in pediatric patients.

Economic analysis of basiliximab in renal transplantation

BACKGROUND

Basiliximab is a chimeric monoclonal directed against the alpha-chain of the interleukin-2 receptor. International studies have shown that it is highly effective in preventing acute rejection in patients receiving Neoral, and causes no measurable incremental toxicity, but its economic value remains unknown.

METHODS

This study employed an economic model to examine the potential economic benefit of basiliximab. Parameter estimates were derived from a randomized, prospective, double-blind study conducted in 21 renal transplant centers in seven countries in which 380 adult primary allograft recipients were randomized within center to receive basiliximab (20 mg i.v.) on days 0 and 4 or placebo in addition to dual immunosuppression with Neoral and steroids. Key clinical events included primary hospitalization, immunosuppressive drug use, patient and graft survival, graft rejection, treatment of rejection, dialysis, and repeat hospitalization. Health resources were valued via a comprehensive electronic cost dictionary, based upon a detailed economic evaluation of renal transplantation in Canada. Medication costs were calculated from hospital pharmacy acquisition costs; basiliximab was assessed a zero cost.

RESULTS

The average estimated cost per patient for the first year after transplant was $55,393 (Canadian dollars) for placebo and $50,839 for basiliximab, rising to $141,690 and $130,592, respectively, after 5 years. A principal component of the cost in both groups was accrued during the initial transplant hospitalization ($14,663 for standard therapy and $14,099 for basiliximab). An additional $15,852 and $14,130 was attributable to continued care, graft loss, and dialysis in the two groups, whereas follow-up hospitalization consumed an additional $15,538 for placebo and $13,916 for basiliximab. The mean incremental cost of dialysis was $5,397 for placebo compared with $3,821 for basiliximab, whereas incremental costs of graft loss were $2,548 compared with $2,295 in the two treatment groups. The principal costs associated with repeat admission to the transplant ward and the general ward were marginally higher for placebo ($7,395 vs. $6,300 and $5,986 vs. $4,625). Treatment of acute rejection and maintenance immunosuppressive drug use were associated with only limited savings as a result of basiliximab (savings <$200 each). Sensitivity analysis indicated that the most influential parameters affecting the savings as a result of using basiliximab were a reduction in the duration of initial and repeat hospitalization followed by the reduced risks of acute rejection and graft loss.

CONCLUSIONS

Before accounting for the cost of the therapy itself, basiliximab produces an estimated economic saving of $4,554 during the first year after transplant, of which $3,344 is attributable to the reduced costs of graft dysfunction, including graft loss and dialysis ($1,722) and follow-up hospitalizations ($1,622). When marketed, basiliximab is expected to cost approximately $3,000 per course (two doses of 20 mg), resulting in a net first-year saving of $1,554. Under these circumstances, basiliximab can be considered a dominant therapy in renal transplantation.

A prospective economic evaluation of basiliximab (Simulect) therapy following renal transplantation

BACKGROUND

Immunoprophylaxis with basiliximab (Simulect), an anti-interleukin-2-receptor (anti-IL-2R; CD25) chimeric monoclonal antibody, has been demonstrated to significantly reduce the incidence of acute cellular rejection in adult renal allograft recipients (32% vs. placebo, p < 0.01).

METHODS

An economic evaluation was conducted as part of a U.S. multi-center, randomized, double-blind, placebo-controlled clinical trial comparing basiliximab plus dual immunosuppressive therapy (cyclosporine modified [Neoral] and corticosteroids) to dual therapy alone. Healthcare resources utilized by the 346 subjects in the 'intent-to-treat' population were prospectively collected over the 1-yr study period. Direct medical costs were determined for all hospitalizations, outpatient provider visits, procedures (excluding the initial transplant procedure), laboratory and diagnostic tests, and immunosuppressants, including basiliximab when administered.

RESULTS

Total first-year medical costs were lower for the basiliximab group than for the placebo group ($28 927 vs. $32 300, difference = $3373). although this difference was not statistically significant. First-year hospital costs for treating acute rejection were also lower for the basiliximab group ($9328 vs. $10761, difference = $1433); however, this difference did not achieve statistical significance. Importantly, the efficacy analysis demonstrated a significant reduction in the incidence of acute rejection (38 vs. 55%, p < 0.01) in the basiliximab arm, and this was accomplished without increasing the overall cost of care. Fewer basiliximab-treated patients (8 vs. 15%,, p = 0.03) were hospitalized. This observation suggested less serious illness and reduced treatment costs among basiliximab-treated patients, because the overall incidence of infection was similar between the groups. The adverse event profile of patients receiving basiliximab was clinically and economically indistinguishable from that of those treated with placebo.

CONCLUSION

Induction immunosuppression with basiliximab, combined with cyclosporine modified and corticosteroids, was therapeutically beneficial and contained medical costs during the initial post-transplant year.

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

BACKGROUND

Basiliximab is an interleukin-2 receptor (CD25) chimeric monoclonal antibody used for acute rejection prophylaxis in renal transplants. In the context of a randomized, double-blind efficacy trial, its population pharmacokinetics and potential exposure-response relationships were explored in de novo kidney allograft recipients receiving 40 mg basiliximab (20 mg on days 0 and 4) in addition to baseline immunosuppressive therapy with cyclosporine microemulsion and corticosteroids.

METHODS

Serial blood samples (8.2+/-1.3 per patient) were collected over 12 weeks after transplant from 169 basiliximab-treated patients, and empirical Bayes estimates of each patient's disposition parameters were derived. The duration of CD25 saturation was estimated as the time over which serum basiliximab concentrations exceeded 0.2 microg/ml. The relationships between pharmacokinetic parameters and demographic-clinical covariates were explored by regression methods and unpaired t-tests.

RESULTS

Basiliximab clearance was 36.7+/-15.2 ml/hr, distribution volume 8.0+/-2.4 L, and half life 7.4+/-3.0 days. Patient weight (range, 44-131 kg) and age (range, 20-69 yrs) each contributed < or =6% to the variability in clearance and volume. Gender, ethnic group, and the presence of proteinuria had no clinically relevant influences on basiliximab disposition. Receptor-saturating basiliximab concentrations were maintained for 36+/-14 days (range, 12-91). There was no apparent relationship between the incidence or day of onset of acute rejection episodes during CD25 saturation and basiliximab concentration (range, 0.2-5.0 microg/ml). In patients who experienced a rejection episode after basiliximab was eliminated from serum (n=33), basiliximab had not been cleared faster than in their rejection-free peers (P=0.322) nor had CD25 been saturated for a shorter period of time (33+/-13 days vs. 37+/-14 days for rejection-free patients, P=0.162).

CONCLUSIONS

There were no demographic or clinical subpopulations not adequately treated with the standard basiliximab dosing regimen. Over the range of CD25 suppression durations observed in this study, extended periods of receptor blockade did not seem to confer an immunoprophylactic advantage compared with shorter periods of receptor suppression.