A randomized prospective trial of OKT3 induction in the current immunosuppression era

Polyclonal and monoclonal antibodies for induction therapy in kidney transplant recipients

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Biologics in organ transplantation

The last two decades have witnessed a pandemic in antibody development, with over 600 entering clinical studies and a total of 28 approved by the FDA and European Union. The incorporation of biologics in transplantation has made a significant impact on allograft survival. Herein, we review the armamentarium of clinical and preclinical biologics used for organ transplantation--with the exception of belatacept--from depleting and IL-2R targeting induction agents to costimulation blockade, B-cell therapeutics, BAFF and complement inhibition, anti-adhesion, and anti-cytokine approaches. While individual agents may be insufficient for tolerance induction, they provide possibilities for reduction of steroid or calcineurin inhibitor use, alternatives to rejection episodes refractory to conventional therapies, and specialized immunosuppression for highly sensitized patients.

Systematic review of randomized controlled trial quality in pediatric kidney transplantation

Limited pediatric-specific research can lead to sub-standard evidence for clinical decision making in children. We sought to systematically evaluate the methodological quality and the reporting standards of randomized controlled trials (RCTs) of transplantation trials in children. We included RCTs of kidney transplant recipients that had enrolled at least one child (aged 17 years or less) and that were reported in English language, peer reviewed journals from 2000 onward in the Cochrane Renal Group's specialized register. Trial reports were assessed against the 22 item checklist of the CONsolidated Standards Of Reporting Trials (CONSORT) statement. Twenty-seven RCTs were included. The reporting of the essential components of the methods, results and discussion domains was unsatisfactory. Mean CONSORT criteria score for the pediatric trials was 67% and 66% for trials including both adults and children (p value for the difference = 1.00). Trial reporting quality in pediatric transplantation trials is not different from trials involving adults. It is evident that the reporting standards of RCTs in both adult and pediatric transplantation require major improvements. This work bench-marks current standards for future quality improvement.

New directions for induction immunosuppression strategy in solid organ transplantation

BACKGROUND

Solid organ transplant centers are increasingly using induction immunosuppression strategies. Induction immunosuppression involves the use of intense therapy at the time of transplantation with the goal of preventing acute rejection and ultimately inducing a tolerogenic state. The objective of this review is to examine specialized induction agents currently in clinical use and highlight novel therapeutics on the horizon for induction immunosuppression.

METHODS

A literature search using the PubMed and MEDLINE databases identified salient basic science and clinical research articles on induction immunosuppression for solid organ transplantation.

CONCLUSIONS

While current induction immunosuppression agents have reduced the incidence of acute rejection, the goal of transplant tolerance has not been realized. Furthermore, the long-term allograft survival rate is not clearly influenced by the practice of induction immunosuppression. New approaches to tolerance induction, such as costimulatory-based therapy, mixed chimerism, and adoptive cellular transfer, hold promise for more effective induction immunosuppression in solid organ transplantation.

Induction immunosuppression

Induction immunosuppression is intense, prophylactic therapy used at the time of transplantation based on the empiric observation that more powerful immunosuppression is required to prevent acute rejection early. In the past decade, there has been a growing trend towards the use of specialized agents such as antibody therapies for induction. In general, these agents have been shown to reduce the rate of acute rejection. However, their use has not been clearly shown to improve long-term transplant outcomes. This overview will review the biological basis for induction immunosuppression and the mechanisms of action of those specialized induction agents currently in clinical use. Clinical trials investigating induction regimens will be evaluated, and an individualized approach to the use of induction immunosuppressants will be presented.

Removal of therapeutic anti-lymphocyte antibodies from human sera prior to anti-human leukocyte antibody testing

Both monoclonal (e.g. Orthoclone (OKT3), rituximab) and polyclonal (e.g. ATGAM, Thymoglobulin (Thymo)) anti-lymphocyte Abs (ALAs) are used extensively in organ transplantation for immunosuppression induction, desensitization, and treatment of acute rejection. ALAs often interfere with post transplant immunologic monitoring. We describe a method that uses magnetic beads to selectively remove ALAs from patient serum. Rabbit anti-mouse Fc-specific (180 mug), or rabbit anti-mouse Fab-specific (180 microg), or rabbit anti-horse heavy and light chain-specific and rabbit anti-horse F(ab')2 (200 microg) (Jackson Immunoresearch) was adsorbed to 6.7 x 10(8) Dynabeads M-280 conjugated with sheep anti-rabbit IgG (Dynal Biotech). Fifty microliters of normal human serum (NHS) with 2 microg/ml of OKT3 or 100 microg/ml ATGAM, Thymo, or rituximab were incubated with conjugated beads for several incubations. NHS containing ALAs before and after treatment by the protocol were incubated with human lymphocytes and labeled with FITC-antibody to immunoglobulin of the species used to produce the particular ALA. Residual ALA was determined using flow cytometry. Average median channel for serum with or without ALA was 11.1 and 0.120, respectively for OKT3; 64.4 and 0.344 for ATGAM; 108.5 and 0.200 for Thymo; and 1022.5 and 11.4 for rituximab. Treatment lowered the median channel for serum with OKT3 to 0.103, 0.309 for ATGAM, 0.199 for Thymo, and 12.1 for rituximab. ALAs can be effectively removed from serum by the use of magnetic beads conjugated with Ab specific for ALA thereby permitting immunologic monitoring without interference.

Induction sirolimus and delayed graft function after deceased donor kidney transplantation in the United States

BACKGROUND/AIMS

Previous studies have reported a link between the use of induction sirolimus (INDSRL) and delayed graft function (DGF) after kidney transplantation. However, none have had sufficient power to adjust for all factors known to be associated with DGF.

METHODS

We conducted a retrospective cohort study of US deceased donor kidney transplantation recipients in the United States Renal Data System (USRDS) from January 1, 2000 to May 31, 2001. Logistic regression analysis was used to model adjusted odds ratios (AOR) for the development of DGF, adjusted for other factors previously reported to be associated with DGF.

RESULTS

Among 8,319 patients meeting inclusion criteria, 361 patients received INDSRL, of whom 98 (27.1%) had DGF, compared to 22.5% among patients who did not receive INDSRL. In multivariate analysis, INDSRL was associated with an increased risk of DGF, with an adjusted odds ratio of 1.42 (95% CI: 1.07-1.90). Other factors associated with DGF were similar to those previously reported. INDSRL was not significantly associated with graft loss at 1 year in Cox regression.

CONCLUSIONS

INDSRL was independently associated with DGF in US deceased donor kidney transplantation recipients, adjusted for all other factors previously shown to be associated with DGF.

Current status of kidney transplant: update 2003

Pediatric transplantation has seen remarkable advances over the past two decades with reduced morbidity and mortality, reduced rejection rates, and improved long-term patient and allograft survival. Infants currently have short-term patient and allograft survival rates better than any other age group; short-term allograft survival rates in CD recipients are equal to those in LD recipients. With decreased rejection, long-term allograft survival is improving dramatically. Transplantation allows for much reduced risks and improved metabolic status, growth and development, and more normal social interactions. The future of transplantation continues to be exciting, with opportunities for reduced immunosuppressive medications and their side effects, and the elusive goal of transplantation tolerance seems within reach.

New developments in immunosuppressive therapy in renal transplantation

The introduction of new immunosuppressive agents and protocols has improved outcomes for renal transplant recipients by decreasing the risk of rejection and by increasing the function and lifespan of the allograft. This article reviews the major changes in the combinations of therapies used: calcineurin inhibitors, target of rapamycin inhibitors, mycophenolate mofetil, non-depleting monoclonal versus depleting monoclonal and polyclonal antibodies for induction and increasing emphasis on protocols for reduction or avoidance of steroids and calcineurin inhibitors. The new agents with novel immunological targets such as anti-CD40 ligand, LEA29Y, FTY720, anti-CD20 (rituximab, Rituxan, Mabthera) and anti-CH52 (alemtuzumab, Campath), which are under development but have yet to survive the rigors of clinical trials are also discussed. In the presence of low early rejection rates, immunosuppressive therapy is setting new goals such as better graft function (glomerular filtration rates), reduction in adverse effects such as hypertension, hyperlipidaemia and drug toxicity and, above all, the prevention of late graft deterioration.