Economics of the antithymocyte globulins Thymoglobulin and Atgam in the treatment of acute renal transplant rejection

Polyclonal and monoclonal antibodies for treating acute rejection episodes in kidney transplant recipients

BACKGROUND

Registry data shows that the incidence of acute rejection has been steadily falling. Approximately 10% to 35% of kidney recipients will undergo treatment for at least one episode of acute rejection within the first post-transplant year. Treatment options include pulsed steroid therapy, the use of an antibody preparation, the alteration of background immunosuppression, or combinations of these options. Over recent years, new treatment strategies have evolved, and in many parts of the world there has been an increase in use of tacrolimus and mycophenolate and a reduction in the use of cyclosporin and azathioprine use as baseline immunosuppression to prevent acute rejection. There are also global variations in use of polyclonal and monoclonal antibodies to treat acute rejection. This is an update of a review published in 2006.

OBJECTIVES

The aim of this systematic review was to: (1) to evaluate the relative and absolute effects of different classes of antibody preparation in preventing graft loss and resolving cellular or humoral rejection episodes when used as a treatment for first episode of rejection in kidney transplant recipients; (2) evaluate the relative and absolute effects of different classes of antibody preparation in preventing graft loss and resolving cellular or humoral rejection episodes when used as a treatment for steroid-resistant rejection in kidney transplant recipients; (3) determine how the benefits and adverse events vary for each type of antibody preparation; and (4) determine how the benefits and harms vary for different formulations of antibody within each type.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 18 April 2017 through contact with the Information Specialist using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in all languages comparing all mono- and polyclonal antibody preparations, given in combination with any other immunosuppressive agents, for the treatment of cellular or humoral graft rejection, when compared to any other treatment for acute rejection were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias of the included studies and extracted data. Statistical analyses were performed using a random-effects model and results expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 11 new studies (18 reports, 346 participants) in this update, bring the total number of included studies to 31 (76 reports, 1680 participants). Studies were generally small, incompletely reported, especially for potential harms, and did not define outcome measures adequately. The risk of bias was inadequate or unclear risk for random sequence generation (81%), allocation concealment (87%) and other bias (87%). There were, however, a predominance of low risk of bias for blinding (75%) and incomplete outcome data (80%) across all the studies. Selective reporting had a mixture of low (58%), high (29%), and unclear (13%) risk of bias.Seventeen studies (1005 participants) compared therapies for first acute cellular rejection episodes. Antibody therapy was probably better than steroid in reversing acute cellular rejection (RR 0.50, 95% CI 0.30 to 0.82; moderate certainty) and preventing subsequent rejection (RR 0.70, 95% CI 0.50 to 0.99; moderate certainty), may be better for preventing graft loss (death censored: (RR 0.80, 95% CI 0.57 to 1.12; low certainty) but there was little or no difference in death at one year. Adverse effects of treatment (including fever, chills and malaise following drug administration) were probably reduced with steroid therapy (RR 23.88, 95% CI 5.10 to 111.86; I2 = 16%; moderate certainty).Twelve studies (576 patients) investigated antibody treatment for steroid-resistant rejection. There was little or no benefit of muromonab-CD3 over ATG or ALG in reversing rejection, preventing subsequent rejection, or preventing graft loss or death. Two studies compared the use of rituximab for treatment of acute humoral rejection (58 patients). Muromonab-CD3 treated patients suffered three times more than those receiving either ATG or T10B9, from a syndrome of fever, chills and malaise following drug administration (RR 3.12, 95% CI 1.87 to 5.21; I2 = 31%), and experienced more neurological side effects (RR 13.10 95% CI 1.43 to 120.05; I2 = 36%) (low certainty evidence).There was no evidence of additional benefit from rituximab in terms of either reversal of rejection (RR 0.94, 95% CI 0.54 to 1.64), or graft loss or death 12 months (RR 1.0, 95% CI 0.23 to 4.35). Rituximab plus steroids probably increases the risk of urinary tract infection/pyelonephritis (RR 5.73, 95% CI 1.80 to 18.21).

AUTHORS' CONCLUSIONS

In reversing first acute cellular rejection and preventing graft loss, any antibody is probably better than steroid, but there is little or no difference in subsequent rejection and patient survival. In reversing steroid-resistant rejection there was little or no difference between different antibodies over a period of 12 months, with limited data beyond that time frame. In treating acute humoral rejection, there was no evidence that the use of antibody therapy conferred additional benefit in terms of reversal of rejection, or death or graft loss.Although this is an updated review, the majority of newer included studies provide additional evidence from the cyclosporin/azathioprine era of kidney transplantation and therefore conclusions cannot necessarily be extrapolated to patients treated with more contemporary immunosuppressive regimens which include tacrolimus/mycophenolate or sirolimus. However, many kidney transplant centres around the world continue to use older immunosuppressive regimes and the findings of this review remain strongly relevant to their clinical practice.Larger studies with standardised reproducible outcome criteria are needed to investigate the outcomes and risks of antibody treatments for acute rejection in kidney transplant recipients receiving contemporary immunosuppressive regimes.

The Cost of Transplant Immunosuppressant Therapy: Is This Sustainable?

A solid organ transplant is life-saving therapy that engenders the use of immunosuppressive medications for the lifetime of the transplanted organ and its recipient. Conventional therapy includes both induction therapy (a biologic that is infused peri-operatively) followed by maintenance therapy. The cost of these medications is a constant concern and the advent of generics has brought this cost down modestly. For those lacking long term insurance coverage, this may be a significant out of pocket expense that is not affordable. Moreover, transplant Centers are managing higher risk transplant recipients that require more complex induction regimens and longer term use of such biologic agents in the context of desensitization or abrogation of de novo antibody mediated injury. While in kidney transplantation, Medicare part B covers three years of medication, there is frequent non-adherence due to cost after that time-point. The impact of the Affordable Care Act remains uncertain at this time. Finally the pipeline of new therapies is limited due to the cost of development of a drug, the inherent cost of clinical studies, and lack of defined endpoints for newer therapies in high risk patients. These new therapies are of high value to the community but will contribute additional burden to current drug costs.

Selection of induction therapy in kidney transplantation

Currently available immunosuppressive agents can be classified into three categories: induction agents, maintenance therapy, and treatment for rejection. This review article will focus on induction immunosuppression. There are three antibodies which are used for induction therapy: the lymphocyte-depleting agents - anti-thymocyte globulin and alemtuzumab, and basiliximab which is nondepleting. Historically, immunosuppressant selection was solely based on efficacy for prevention of rejection. In the current era of transplantation, it is now common practice in the transplant community to select induction therapy on the basis of risk-benefit considerations for each patient. This article will focus on the efficacy of available induction agents and the selection of induction agent based on donor and recipient risk factors.

A review of the costs and cost effectiveness of interventions in chronic kidney disease: implications for policy

Given rising healthcare costs and a growing population of patients with chronic kidney disease (CKD), there is an urgent need to identify health interventions that provide good value for money. For this review, the English-language literature was searched for studies of interventions in CKD reporting an original incremental cost-utility (cost per QALY) or cost-effectiveness (cost per life-year) ratio. Published cost studies that did not report cost-effectiveness or cost-utility ratios were also reviewed. League tables were then created for both cost-utility and cost-effectiveness ratios to assess interventions in patients with stage 1-4 CKD, waitlist and transplant patients and those with end-stage renal disease (ESRD). In addition, the percentage of cost-saving or dominant interventions (those that save money and improve health) was compared across these three disease categories. A total of 84 studies were included, contributing 72 cost-utility ratios, 20 cost-effectiveness ratios and 42 other cost measures. Many of the interventions were dominant over the comparator, indicating better health outcomes and lower costs. For the three disease categories, the greatest number of dominant or cost-saving interventions was reported for stage 1-4 CKD patients, followed by waitlist and transplant recipients and those with ESRD (91%, 87% and 55% of studies reporting a dominant or cost-saving intervention, respectively). There is evidence of opportunities to lower costs in the treatment of patients with CKD, while either improving or maintaining the quality of care. In order to realize these cost savings, efforts will be required to promote and effectively implement changes in treatment practices.

Polyclonal Antibodies in Renal Transplantation—A Relook

Polyclonal antibodies have been used in renal transplantation for the past four decades. Increasing knowledge regarding their varied mechanisms of action have confirmed their versatility in clinical practice. They can be used for induction, reversing acute rejections (especially those resistant to steroids), and possibly conferring an element of allotolerance, thereby reducing chronic allograft nephropathy. Their recent usage as IV bolus, single-dose, preoperative infusion as induction therapy in renal transplantation is an attractive and extremely cost-effective strategy, especially in a developing country such as India.

Rabbit antithymocyte globulin induction therapy in adult renal transplantation

Rabbit antithymocyte globulin (rATG) and horse antithymocyte globulin (horse ATG) are the polyclonal antithymocyte agents available for use in solid organ transplantation in the United States. Horse ATG is indicated for induction immunosuppression and for treatment of acute rejection episodes after kidney transplantation; rATG is indicated for treatment of acute rejection only. However, rATG is commonly used in clinical practice as an induction immunosuppressive agent, instigating many questions regarding appropriate dosing, tolerability, safety, and efficacy. Available evidence supports the use of rATG as an induction agent in adult renal transplant recipients. The use of this product for induction therapy has been studied in conjunction with a full-dose, triple-therapy maintenance regimen (sequential quadruple immunosuppression) consisting of a calcineurin inhibitor, an antimetabolite, and corticosteroids. Rabbit ATG has a proven safety and efficacy profile both as treatment of acute rejection and as induction therapy in patients undergoing kidney transplantation. The most common adverse events associated with rATG are cytokine release syndrome, thrombocytopenia, and lymphopenia. Results of early studies showed an increased rate of cytomegalovirus disease associated with rATG treatment, but recent studies indicate that routine administration of modern antiviral prophylaxis can reduce this risk. Current practice with rATG is evolving to minimize lifelong exposure to calcineurin inhibitors and corticosteroids.

Cyclosporine Prolongs Delayed Graft Function in Kidney Transplantation: Are Rabbit Anti-Human Thymocyte Globulins the Answer?

BACKGROUND

Cyclosporine (CsA) nephrotoxicity may prolong duration of anuria in renal transplant patients with delayed graft function (DGF). Thus, many Transplant Centers tend to delay CsA treatment in order to accelerate renal function recovery.

METHODS

In this single-center, retrospective analysis we compared the outcomes of 40 renal transplant patients with DGF given a CsA-based (n = 17) regimen since the day of transplant or a CsA-sparing regimen (n = 23) based on early treatment with rabbit anti-human thymocyte globulin (RATG) and delayed CsA administration. We studied all patients with DGF who received a first or second graft at the Bergamo Transplant Center from January 1992 to March 2000.

RESULTS

Patients given RATG as compared to those on CsA had significantly shorter duration of anuria (11.0 +/- 5.6 vs. 19.6 +/- 8.9 days; p < 0.005) and of initial hospitalization (17.4 +/- 4.3 vs. 27.4 +/- 10.4 days; p < 0.001). Throughout the whole study period, 4 patients on RATG as compared to 6 on CsA had an acute rejection episode (p > 0.05). However, no patient on RATG as compared to 4 on CsA had an acute rejection during the anuria period (p < 0.05). Costs including hospitalization, dialysis treatment and study drugs were significantly lower in RATG than in CsA patients (EUR 29,944 +/- 7,281 vs. 36,795 +/- 13,656; p < 0.05).

CONCLUSIONS

In renal transplant patients with DGF, early RATG treatment with delayed CsA administration accelerated renal function recovery and patient discharge, prevented occult rejections throughout the anuria period and significantly decreased the treatment costs.