Low dose antithymocyte globulins in renal transplantation: daily versus intermittent administration based on T-cell monitoring

Prediction of very early subclinical rejection with machine learning in kidney transplantation

Protocol biopsy is a reliable method for assessing allografts status after kidney transplantation (KT). However, due to the risk of complications, it is necessary to establish indications and selectively perform protocol biopsies by classifying the high-risk group for early subclinical rejection (SCR). Therefore, the purpose of this study is to analyze the incidence and risk factors of early SCR (within 2 weeks) and develop a prediction model using machine learning. Patients who underwent KT at Samsung Medical Center from January 2005 to December 2020 were investigated. The incidence of SCR was investigated and risk factors were analyzed. For the development of prediction model, machine learning methods (random forest, elastic net, extreme gradient boosting [XGB]) and logistic regression were used and the performance between the models was evaluated. The cohorts of 987 patients were reviewed and analyzed. The incidence of SCR was 14.6%. Borderline cellular rejection (BCR) was the most common type of rejection, accounting for 61.8% of cases. In the analysis of risk factors, recipient age (OR 0.98, p = 0.03), donor BMI (OR 1.07, p = 0.02), ABO incompatibility (OR 0.15, p < 0.001), HLA II mismatch (two [OR 6.44, p < 0.001]), and ATG induction (OR 0.41, p < 0.001) were associated with SCR in the multivariate analysis. The logistic regression prediction model (average AUC = 0.717) and the elastic net model (average AUC = 0.712) demonstrated good performance. HLA II mismatch and induction type were consistently identified as important variables in all models. The odds ratio analysis of the logistic prediction model revealed that HLA II mismatch (OR 6.77) was a risk factor for SCR, while ATG induction (OR 0.37) was a favorable factor. Early SCR was associated with HLA II mismatches and induction agent and prediction model using machine learning demonstrates the potential to predict SCR.

The use of lymphocyte-depleting antibodies in specific populations of kidney transplant recipients: A systematic review and meta-analysis

BACKGROUND

Recommendations of the use of antibody induction treatments in kidney transplant recipients (KTR) are based on moderate quality and historical studies. This systematic review aims to reevaluate, based on actual studies, the effects of different antibody preparations when used in specific KTR subgroups.

METHODS

We searched MEDLINE and CENTRAL and selected randomized controlled trials (RCT) and observational studies looking at different antibody preparations used as induction in KTR. Comparisons were categorized into different KTR subgroups: standard, high risk of rejection, high risk of delayed graft function (DGF), living donor, and elderly KTR. Two authors independently assessed the risk of bias.

RESULTS

Thirty-seven RCT and 99 observational studies were finally included. Compared to anti-interleukin-2-receptor antibodies (IL2RA), anti-thymocyte globulin (ATG) reduced the risk of acute rejection at two years in standard KTR (RR 0.74, 95%CI 0.61-0.89) and high risk of rejection KTR (RR 0.55, 95%CI 0.43-0.72), but without decreasing the risk of graft loss. We did not find significant differences comparing ATG vs. alemtuzumab or different ATG dosages in any KTR group.

CONCLUSIONS

Despite many studies carried out on induction treatment in KTR, their heterogeneity and short follow-up preclude definitive conclusions to determine the optimal induction therapy. Compared with IL2RA, ATG reduced rejection in standard-risk, highly sensitized, and living donor graft recipients, but not in high DGF risk or elderly recipients. More studies are needed to demonstrate beneficial effects in other KTR subgroups and overall patient and graft survival.

Association between cumulative rATG induction doses and kidney graft outcomes and adverse effects in kidney transplant patients: a systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis were performed to explore the association between rabbit thymoglobulin (rATG) doses and transplant-related efficacy and safety outcomes.

METHODS

We searched PubMed and Scopus databases from inception up to June 2020. The primary efficacy and safety endpoints in kidney transplant recipients were evaluated.

RESULTS

Data of 23 cohort studies (3457 patients) and three RCTs (154 patients) were extracted and analyzed. rATG doses of ≤4.5 m/kg was associated with lower rates of biopsy proven acute rejection, cytomegalovirus infection, BK virus infection, and malignancy with a comparable rate of delayed graft function, patients' mortality, and death-censored graft loss compared to rATG total doses of 4.5-6 mg/kg or more than 6 mg/kg. The rATG doses of 3-4.5 mg/kg was associated with better outcomes in dose-response analysis.

EXPERT OPINION

Cumulative rATG induction doses as much as 3-4.5 mg/kg is as effective as higher doses regarding to allograft and patient outcomes while minimizing potential adverse effects in kidney transplant recipients.

Relationship Between Antithymocyte Globulin Concentrations and Lymphocyte Sub-Populations in Kidney Transplant Patients

BACKGROUND

Rabbit antithymocyte globulins (rATGs) are polyclonal antibodies used to prevent acute cellular rejection in kidney transplantation. Their dosing remains largely empirical and the question of an individualized dose is still unresolved.

METHODS

Data from a prospective study in 17 kidney transplant patients were used to develop a model describing the dose-concentration-response relationship of rATG with T-lymphocyte subpopulation counts over time. The model was validated using an independent cohort of kidney transplant patients treated by rATG in the same center.

RESULTS

Pharmacokinetics of rATG was described using a two-compartment model integrating a third compartment and a target-mediated elimination for active rATG. The kinetics of CD3⁺, CD4⁺, CD8⁺, and CD3^-CD56⁺ cell counts over time were described by a pharmacokinetic-pharmacodynamic model with transit compartments, integrating both CD3^-CD56⁺-independent and CD3^-CD56⁺-dependent rATG-mediated lymphocyte depletion, and a positive feedback. Elimination of rATG was influenced by age and body surface area, while its distribution was also influenced by body surface area. CD3⁺ proliferation rate decreased with age and CD3^-CD56⁺-mediated elimination was influenced by the V158F-FCGR3A polymorphism. Binary efficacy and tolerance endpoints were defined as a CD3⁺ count < 20 mm^-3 for at least 7 days and a CD4⁺ count > 200 mm^-3 at 1 year, respectively. Simulations showed that increasing or decreasing the standard 6-mg/kg dose will impact both tolerance and efficacy, while a dose decrease may be beneficial in elderly patients.

CONCLUSIONS

Our results can be used to design prospective clinical trials testing dose individualization based on patients' characteristics.

CLINICAL TRIAL REGISTRATION

Eudract No. 2009-012673-35.

A call for transplant stewardship: The need for expanded evidence-based evaluation of induction and biologic-based cost-saving strategies in kidney transplantation and beyond

Rising expenditures threaten healthcare sustainability. While transplant programs are typically considered profitable, transplant medications are expensive and frequently targeted for cost savings. This review aims to summarize available literature supporting cost-containment strategies used in solid organ transplant. Despite widespread use of these tactics, we found the available evidence to be fairly low quality. Strategies mainly focus on induction, particularly rabbit antithymocyte globulin (rATG), given its significant cost and the lack of consensus surrounding dosing. While there is higher-quality evidence for high single-dose rATG, and dose-rounding protocols to reduce waste are likely low risk, more aggressive strategies, such as dosing rATG by CD3+ target-attainment or on ideal-body-weight, have less robust support and did not always attain similar efficacy outcomes. Extrapolation of induction dosing strategies to rejection treatment is not supported by any currently available literature. Cost-saving strategies for supportive therapies, such as IVIG and rituximab also have minimal literature support. Deferral of high-cost agents to the outpatient arena is associated with minimal risk and increases reimbursement, although may increase complexity and cost-burden for patients and infusion centers. The available evidence highlights the need for evaluation of unique patient-specific clinical scenarios and optimization of therapies, rather than simple blanket application of cost-saving initiatives in the transplant population.

Considerations and controversies of pharmacologic management of the pediatric kidney transplant recipient

Pediatric kidney transplantation has experienced considerable growth and improvement in patient and allograft outcomes over the past 20 years, in part due to advancements in immunosuppressive regimens and management. Despite this progress, care for this unique population can be challenging due to limited pediatric transplant data and trials, intricacies related to differences in children and adolescents compared with their adult counterparts, and limitations to long-term survival facing all solid organ transplant populations. Immunosuppression and infection prevention practices vary from one pediatric transplant center to another and clinical controversies exist surrounding treatment and dosing. This review aims to summarize key aspects of pharmacologic management in this population and present pertinent data that describe the influence of practice to serve as a resource for practitioners caring for this unique specialty patient population. Additionally, this review highlights select controversies that exist within pediatric kidney transplantation.

Reassessing Rabbit Antithymocyte Globulin Induction in Kidney Transplantation (RETHINK): An Analysis of the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) Registry

Supplemental Digital Content is available in the text.

Background.

There is no consensus on rabbit antithymocyte globulin (rATG) dose used for induction immunosuppression in pediatric kidney transplants. We aimed to identify whether a lower rATG dose provides safe and effective immunosuppression compared with a higher dose.

Methods.

We retrospectively analyzed all first-time kidney transplant recipients (aged <21 y) in the North American Pediatric Renal Trials and Collaborative Studies registry since 1998 on mycophenolate mofetil– and tacrolimus-based immunosuppression with rATG induction. An a priori cutoff of 7.5 mg/kg cumulative rATG dose was used to identify low (<7.5 mg/kg) and high (≥7.5 mg/kg) exposure groups. Primary outcome was time to first-acute rejection episode. Secondary outcomes included graft function, patient survival, hospitalizations due to infections, and time to first-posttransplant lymphoproliferative disorder episode.

Results.

Four hundred fifty-five patients met inclusion criteria (59% male, 49% whites, 26% blacks, 38% living donor source). Median cumulative rATG dose was 6.8 mg/kg with a median of 5 doses and a median 1.5 mg/kg/dose introduced at a median of postoperative 0 days. Sixty-four percent received <7.5 mg/kg total rATG. There was no difference in age at transplant, gender, race, end-stage renal disease causes, or HLA mismatch among groups. Time to first-acute rejection was similar (P = 0.07). There was no significant difference in graft or patient survival or time to posttransplant lymphoproliferative disorder. Hospitalization for infection rates was similar.

Conclusions.

These data demonstrate a wide variation in cumulative rATG induction dose. A smaller rATG dose <7.5 mg/kg may provide effective and safe immunosuppression compared with a higher dose.

Polyclonal anti T-lymphocyte antibody therapy monitoring in kidney transplant recipients: comparison of CD3+ T cell and total lymphocyte counts

Objective:

To investigate the correlation between total lymphocyte and CD3⁺ T cell counts in peripheral blood in renal transplant patients treated with anti-thymocyte globulin, and discuss related outcomes.

Methods:

A single-center, retrospective study involving 226 patients submitted to kidney transplant between 2008 and 2013, and treated with anti-thymocyte globulin for induction or treatment of cellular rejection. Doses were adjusted according to CD3⁺ T cell or total lymphocyte counts in peripheral blood.

Results:

A total of 664 paired samples were analyzed. The Spearman's correlation coefficient was 0.416 (p<0.001) for all samples combined; the overall Kappa coefficient was 0.267 (p<0.001). Diagnostic parameters estimated based on total lymphocyte counts were also calculated using the number of CD3⁺ T cells (gold standard), with a cut off of >20 cells/mm³.

Conclusion:

Total lymphocyte and CD3⁺ T cell counts in peripheral blood are not equivalent monitoring strategies in anti-thymocyte globulin therapy.

A Proposal for Early Dosing Regimens in Heart Transplant Patients Receiving Thymoglobulin and Calcineurin Inhibition

There is currently no consensus regarding the dose or duration of rabbit antithymocyte globulin (rATG) induction in different types of heart transplant patients, or the timing and intensity of initial calcineurin inhibitor (CNI) therapy in rATG-treated individuals. Based on limited data and personal experience, the authors propose an approach to rATG dosing and initial CNI administration. Usually rATG is initiated immediately after exclusion of primary graft failure, although intraoperative initiation may be appropriate in specific cases. A total rATG dose of 4.5 to 7.5 mg/kg is advisable, tailored within that range according to immunologic risk and adjusted according to immune monitoring. Lower doses (eg, 3.0 mg/kg) of rATG can be used in patients at low immunological risk, or 1.5 to 2.5 mg/kg for patients with infection on mechanical circulatory support. The timing of CNI introduction is dictated by renal recovery, varying between day 3 and day 0 after heart transplantation, and the initial target exposure is influenced by immunological risk and presence of infection. Rabbit antithymocyte globulin and CNI dosing should not overlap except in high-risk cases. There is a clear need for more studies to define the optimal dosing regimens for rATG and early CNI exposure according to risk profile in heart transplantation.

Cumulative Doses of T-Cell Depleting Antibody and Cancer Risk after Kidney Transplantation

T-cell depleting antibody is associated with an increased risk of cancer after kidney transplantation, but a dose-dependent relationship has not been established. This study aimed to determine the association between cumulative doses of T-cell depleting antibody and the risk of cancer after kidney transplantation. Using data from the Australian and New Zealand Dialysis and Transplant Registry between 1997–2012, we assessed the risk of incident cancer and cumulative doses of T-cell depleting antibody using adjusted Cox regression models. Of the 503 kidney transplant recipients with 2835 person-years of follow-up, 276 (55%), 209 (41%) and 18 (4%) patients received T-cell depleting antibody for induction, rejection or induction and rejection respectively. The overall cancer incidence rate was 1,118 cancers per 100,000 patient-years, with 975, 1093 and 1377 cancers per 100,000 patient-years among those who had received 1–5 doses, 6–10 doses and >10 doses, respectively. There was no association between cumulative doses of T cell depleting antibody and risk of incident cancer (1–5: referent, 6–10: adjusted hazard ratio (HR) 1.19, 95%CI 0.48–2.95, >10: HR 1.42, 95%CI 0.50–4.02, p = 0.801). This lack of association is contradictory to our hypothesis and is likely attributed to the low event rates resulting in insufficient power to detect significant differences.

Drug target molecules to guide immunosuppression

The individual and interindividual variability of response to immunosuppressants combined with the prevailing concept of lifelong immunosuppression following any organ transplantation motivates the search for methods to further individualize such therapy. Traditional therapeutic drug monitoring, adapting dose according to concentrations in blood, targets the pharmacokinetic variability. It has been increasingly recognized, however, that there is also a considerable variability in the response to a given concentration. Attempts to overcome this variability in response include the efforts to identify relevant targets and methods for pharmacodynamic monitoring. For several of the currently used immunosuppressants there is experimental data suggesting markers that are relevant as indicators for individual monitoring of the effects of these drugs. There are also some clinical data to support these approaches; however what is generally missing, are studies that in a prospective manner demonstrates the benefits and effects on outcome. The monitoring of antithymocyte globulin by lymphocyte subset counts is actually the only well established example of pharmacodynamic monitoring. For drugs such as MPA and mTOR inhibitors, there are candidates such as IMPDH activity expression and p70SK6 phosphorylation status, respectively. The monitoring of CNIs using assays for NFAT RGE, either alone or combined with concentration measurements, is already well documented. Even here, some further investigations relating to the categories of organ transplant, combination of immunosuppressants etc. will be requested. Although some further standardization of the assay is warranted and there is a need for specific recommendations of target levels and how to adjust dose, the NFAT RGE approach to pharmacodynamic monitoring of CNIs may be close to implementation in clinical routine.

New directions for rabbit antithymocyte globulin (Thymoglobulin(®)) in solid organ transplants, stem cell transplants and autoimmunity

In the 30 years since the rabbit antithymocyte globulin (rATG) Thymoglobulin^® was first licensed, its use in solid organ transplantation and hematology has expanded progressively. Although the evidence base is incomplete, specific roles for rATG in organ transplant recipients using contemporary dosing strategies are now relatively well-identified. The addition of rATG induction to a standard triple or dual regimen reduces acute cellular rejection, and possibly humoral rejection. It is an appropriate first choice in patients with moderate or high immunological risk, and may be used in low-risk patients receiving a calcineurin inhibitor (CNI)-sparing regimen from time of transplant, or if early steroid withdrawal is planned. Kidney transplant patients at risk of delayed graft function may also benefit from the use of rATG to facilitate delayed CNI introduction. In hematopoietic stem cell transplantation, rATG has become an important component of conventional myeloablative conditioning regimens, following demonstration of reduced acute and chronic graft-versus-host disease. More recently, a role for rATG has also been established in reduced-intensity conditioning regimens. In autoimmunity, rATG contributes to the treatment of severe aplastic anemia, and has been incorporated in autograft projects for the management of conditions such as multiple sclerosis, Crohn’s disease, and systemic sclerosis. Finally, research is underway for the induction of tolerance exploiting the ability of rATG to induce immunosuppresive cells such as regulatory T-cells. Despite its long history, rATG remains a key component of the immunosuppressive armamentarium, and its complex immunological properties indicate that its use will expand to a wider range of disease conditions in the future.

Immunosuppression and allograft rejection following lung transplantation: evidence to date

The enduring success of lung transplantation is built on the use of immunosuppressive drugs to stop the immune system from rejecting the newly transplanted lung allograft. Most patients receive a triple-drug maintenance immunosuppressive regimen consisting of a calcineurin inhibitor, an antiproliferative and corticosteroids. Induction therapy with either an antilymphocyte monoclonal or an interleukin-2 receptor antagonist are prescribed by many centres aiming to achieve rapid inhibition of recently activated and potentially alloreactive T lymphocytes. Despite this generic approach acute rejection episodes remain common, mandating further fine-tuning and augmentation of the immunosuppressive regimen. While there has been a trend away from cyclosporine and azathioprine towards a preference for tacrolimus and mycophenolate mofetil, this has not translated into significant protection from the development of chronic lung allograft dysfunction, the main barrier to the long-term success of lung transplantation. This article reviews the problem of lung allograft rejection and the evidence for immunosuppressive regimens used both in the short- and long-term in patients undergoing lung transplantation.

A novel mechanism of anti-T-lymphocyte globulin mediated by fractalkine in renal ischemia-reperfusion injury in rats

BACKGROUND

Ischemia-reperfusion injury (IRI) is among the main challenges in kidney transplantation. It causes delayed graft function and graft loss in long-term follow-up studies. Anti-T lymphocyte globulin (ATG), a common induction immunosuppressive, has been used in kidney transplantation to prevent rejection. Fractalkine (FKN) is among the main chemokines involved in IRI. This study was designed to identify the relationship between ATG and FKN after warm ischemia in rat kidneys.

METHODS

Rats were divided into three groups: Control, IRI+normal saline(NS) and IRI+ATG. After IRI was initiated, rats received a dose of ATG or NS during surgery as well as two more doses at 24 and 48 hours after surgery. All rats were humanely killed at 72 hours.

RESULTS

The concentration of FKN as well as dendritic cells (DC) and macrophages were lower in both peripheral blood and the injured kidney among ATG-treated versus control rats. Additionally cell necrosis, cytoplasmic vacuolization, cast formation, and tubular dilatation were improved among ATG-treated rats. Serum creatinine levels were lower in rats that received ATG.

CONCLUSION

ATG depleted the concentration of FKN, which inhibits migrations of DCs and macrophages into the kidney, and reduces IRI-related pathology.

Monitoring of CD3(+) T-cell count in patients receiving antithymocyte globulin induction after cadaveric renal transplantation

AIM

Although antithymocyte globulin (ATG) has been used for years, its ideal dose and administration period is obscure. Herein, we sought to use the CD3(+) cell count to detect the optimal ATG dosage.

MATERIAL AND METHODS

Twenty-one patients who underwent cadaveric donor renal transplantation from January 2009 to January 2012 received a 1 mg/kg ATG initial dose at the time of the operation. Patients were randomized into 2 cohorts. Group 1 (n = 11) received ATG according to the clinical and total lymphocyte count and group 2 (n = 10), the dose was tailored according to the CD3(+) cell count. We compared the total and daily ATG dosages, ATG administration period, side effects of ATG, the number of days to a serum creatinine level <2 mg/dL, graft function at 3 months, acute rejection episodes, infection rates, costs of CD3(+) analysis, and ATG amounts.

RESULTS

Both groups showed similar gender, age, and human leukocyte antigen matching data. There was no difference in presensitizing events or panel-reactive antibody class 1 and 2 levels. The number of days to a serum creatinine level of <2 mg/dL was 11 ± 1.5 for group 1 versus 10.4 ± 0.8 for group 2 (P = .45). Between groups 1 and 2, there was a significant difference between the mean total (P = .031) and mean daily ATG dosages (P = .006). We used a total dose of 3800 mg ATG for group 1 and 2200 mg for group 2 and for the group 2 who underwent 43 CD3(+) cell counts. The expenditure per patient was 20% higher among group 1 than group 2.

CONCLUSION

Determination of appropriate ATG dosages by CD3(+) cell counts was useful, reliable, and cost effective.

The role of Thymoglobulin induction in kidney transplantation: an update

The rabbit antithymocyte globulin Thymoglobulin first became available over 25 yr ago and is the most widely used lymphocyte-depleting preparation in solid organ transplantation. Thymoglobulin targets a wide range of T-cell surface antigens as well as natural killer-cell antigens, B-cell antigens, plasma cell antigens, adhesion molecules and chemokine receptors, resulting in profound, long-lasting T-cell depletion. Randomized studies have established the anti-rejection efficacy of Thymoglobulin in kidney transplantation. Experimental and clinical data suggest that Thymoglobulin administration may ameliorate ischemia reperfusion injury, thus reducing the incidence of delayed graft function (DGF). Studies have demonstrated the benefit of using Thymoglobulin to facilitate immunosuppression minimization, both for corticosteroid and calcineurin inhibitor (CNI) withdrawal or avoidance, with potential improvement in cardiovascular and renal outcomes. The optimal cumulative dose for Thymoglobulin induction is 6-7.5 mg/kg, with vigilant short- and long-term monitoring of hematological status. Induction with Thymoglobulin is now indicated in immunologically high-risk patients, in those at increased risk of DGF and to maintain efficacy in low-risk transplant recipients receiving steroid or CNI minimization or avoidance regimens. We suggest that in future trials Thymoglobulin be tested with costimulation signal blockers and other immunosuppressants with the objective of establishing operational tolerance.

Comprehensive immune monitoring reveals profound immunological changes in pancreas after kidney (PAK) transplant recipients

Pancreas transplantation is a therapeutic option for the management of complicated Type 1 diabetes mellitus. While standard protocols include use of induction therapy followed by maintenance immunosuppression, the amount, frequency and duration of induction treatment has not been clearly defined. While the effect of various induction regimens on lymphocytes has been demonstrated, a prospective immune monitoring approach is not widely used to determine "immunological titration" of immunosuppression. In this study, we analyzed a patient cohort with pancreas after kidney transplantation and measured a wide range of quantitative and functional T and B cell parameters to identify those that would provide greatest value in personalized prospective immune assessment and design of immunosuppression. While there were significant quantitative differences observed in the 2 groups of PAK patients for various lymphocyte subsets, the notable observation was that lymphocyte subset quantitation was uninformative with regard to T cell function. Patients with normal lymphocyte counts had impaired T cell functional responses and vice versa. The use of immune monitoring to determine optimal IS regimens needs to be studied further to facilitate personalized management of immunosuppression with reduced risk of allograft rejection in PAK, and limited morbidity and mortality related to infection and malignancy.

Clinical and Economic Analysis of Delayed Administration of Antithymocyte Globulin for Induction Therapy in Kidney Transplantation

Context

The increasing number of marginal deceased kidney donors and an aging recipient population, prolonged hospitalization, and increased costs have destabilized the economic viability of kidney transplants.

Objective

To determine if a delay in the administration of the day-of-discharge dose of rabbit antithymocyte globulin would result in equivalent clinical outcomes with cost savings.

Design

Single-center, prospective, observational before-and-after study of adult kidney transplant recipients who received induction with rabbit antithymocyte globulin. Intervention—Patients who received a transplant between June 2006 and February 2009 and received rabbit antithymocyte globulin served as the control group. Patients who received a transplant between March 2009 and August 2010 and received rabbit antithymocyte globulin had the day-of-discharge dose delayed to the following day and administered in the clinic. A total of 231 patients (146 in the control group, 85 in the study group) were included. Baseline demographic and clinical characteristics were similar in the 2 groups.

Results

Patients who had delayed administration of rabbit antithymocyte globulin had shorter stays (3.9 vs 3.1 days, P .001) and reduced inpatient costs for rabbit antithymocyte globulin (mean $860/patient); these changes were achieved without affecting acute rejection rates (5% vs 5%, P>> .99) or readmission rates. In conclusion, delayed inpatient administration of rabbit antithymocyte globulin provided identical clinical outcomes while helping to reduce inpatient costs and increase timely discharges.

Renal transplantation in the setting of early steroid withdrawal: a comparison of rabbit antithymocyte globulin induction dosing in two eras

BACKGROUND

Modern immunosuppression and rabbit antithymocyte globulin (rATG) have facilitated the success of early steroid withdrawal (ESW) protocols. Little data exist on optimal rATG dosing in ESW protocols.

METHODS

Rejection at 12 months in era 1 (four doses of rATG, 1.25 mg/kg) vs. era 2 (three doses of rATG, 1.25 mg/kg) was the primary endpoint. Secondary endpoints included patient and graft survival, renal function and infectious complications. Factors associated with rejection at 1 year were identified.

RESULTS

199 patients received rATG induction and ESW: 102 in era 1 and 97 in era 2. Compared to era 1, era 2 was not associated with worse outcomes, including rejection, renal function, infection or graft survival. Rejection at 1 year and uncensored graft survival differed between the dosing groups. Rejection rates were significantly higher in the <4 mg/kg group compared to the 4-5.9-mg/kg and the ≥6-mg/kg groups, whereas uncensored graft survival was the lowest in the ≥6-mg/kg group. Factors associated with rejection at 12 months included: rATG dose received of 4-5.9 versus <4 mg/kg (OR 0.20, 95% CI 0.036-0.85, p = 0.026); recipient age (per year, OR 0.94, 95% CI 0.89-1.0, p = 0.038); panel reactive antibody 10-79.9 versus <10% (OR 5.4, 95% CI 1.2-25, p = 0.030) and rATG dose held (OR 4.0, 95% CI 1.0-15, p = 0.049).

CONCLUSIONS

A comparison of rATG dosing based on era did not result in a significant difference in rejection, renal function, infection or graft survival. However, when evaluating the study population based on actual dose received there were notable differences in both rejection rates and uncensored graft survival.

A CD3+ count-based thymoglobulin induction regimen permits delayed introduction of calcineurin inhibitors in kidney transplantation

BACKGROUND

Withholding calcineurin inhibitors (CNIs) can be considered when graft function is inadequate following kidney transplantation (KT). Thymoglobulin (rATG) can be used to prevent acute rejection while CNIs are being withheld. Here, we report our results of a novel CNI-sparing induction protocol, which utilizes a CD3+ cell count-based rATG treatment regimen when delayed graft function (DGF) develops in the immediate postoperative period.

METHODS

In a cohort of 153 consecutive deceased-donor KT recipients, all received a single intraoperative dose of basiliximab; 84 subsequently developed DGF and therefore received rATG (rATG+ group), while 69 demonstrated immediate graft function and received CNIs (rATG- group).

RESULTS

In the rATG+ group, mean duration of therapy was 8.5±6.0 d, permitting CNI initiation to be delayed until postoperative day 10.3±6.2. Cumulative dose of rATG was only 5.1±4.5 mg/kg while targeting CD3+ counts of ≤30 cells/mm3. CD3+ counts were reduced to a mean of 16.7±17.0 cells/mm3 during therapy. At one yr, patient and graft survival rates were 97.6% and 92.9%, respectively, while the frequency of infections and malignancies were not significantly increased compared to the rATG- group.

CONCLUSION

A unique induction regimen successfully delayed CNI initiation by using modest doses of rATG to deplete CD3+ cells, while yielding excellent long-term graft outcome without increased risk of infection or malignancy.

Rabbit antithymocyte globulin (thymoglobulin): 25 years and new frontiers in solid organ transplantation and haematology

The more than 25 years of clinical experience with rabbit antithymocyte globulin (rATG), specifically Thymoglobulin, has transformed immunosuppression in solid organ transplantation and haematology. The utility of rATG has evolved from the treatment of allograft rejection and graft-versus-host disease to the prevention of various complications that limit the success of solid organ and stem cell transplantation. Today, rATG is being successfully incorporated into novel therapeutic regimens that seek to reduce overall toxicity and improve long-term outcomes. Clinical trials have demonstrated the efficacy and safety of rATG in recipients of various types of solid organ allografts, recipients of allogeneic stem cell transplants who are conditioned with both conventional and nonconventional regimens, and patients with aplastic anaemia. Over time, clinicians have learnt how to better balance the benefits and risks associated with rATG. Advances in the understanding of the multifaceted mechanism of action will guide research into new therapeutic areas and future applications.

Evolution of coronary artery calcifications following kidney transplantation: relationship with osteoprotegerin levels

We prospectively assessed the evolution of coronary artery calcification (CAC) and osteoprotegerin (OPG) levels after renal transplantation (RT). Eighty-three recipients were followed-up prospectively during 1 year. Blood was collected before (baseline) and after RT for determination of mineral metabolism parameters including OPG. CAC was measured by multidetector computed tomography at transplantation (baseline) and 1 year later. Progression of CAC was defined as a difference between the follow-up square-root transformed volume (SRV) and the baseline SRV >or= 2.5. By multivariate analysis, baseline OPG level, age and low LDL levels were significantly associated with baseline CAC. RT was accompanied by mineral metabolism improvement with a decrease of OPG from 955 [395-5652] to 527 [217-1818] pg/mL and parathyroid hormone from 94 [1-550] to 62 [16-410] pg/mL. Thirty-one percent of patients did not exhibit CAC at baseline. CAC diminished in 14.5%, stabilized in 59.2% and progressed in 26.3% of patients. Baseline CAC was associated with progression (OR 2.92 [1.02-8.36]). No significant association was found between OPG and CAC progression despite a higher baseline OPG level in progressors (1046 [456-3285]) vs. non-progressors (899 [396-5952] pg/mL). CAC at baseline, but not 1 year after RT, is independently associated with baseline OPG; posttransplant CAC progression is predicted by baseline CAC score.

Does reduction in immunosuppression in viremic patients prevent BK virus nephropathy in de novo renal transplant recipients? A prospective study

BACKGROUND

BK virus nephropathy (BKVN) is a severe complication of renal transplantation, resulting in graft loss in >50% of cases. Because patients with BKV viremia are at high risk for developing BKVN, the aim of our study was to analyze whether early reduction of immunosuppression (IS) could prevent BKVN in viremic patients.

METHODS

BKV viruria was prospectively screened every 3 months by real-time polymerase chain reaction during the first year after transplantation in 123 consecutive renal transplant recipients. Plasma viral load was measured by polymerase chain reaction whenever viruria was positive; in viremic patients a graft biopsy was systematically performed and IS was reduced.

RESULTS

Viruria, viremia, and BKVN occurred in 48.8%, 10.5%, and 2.4% of patients, respectively. In the 13 patients with positive viremia, initial graft biopsy showed BKVN in two. After reduction of IS in patients without BKVN, viremia disappeared in 8 of 11, decreased in 2 of 11, and increased in one patient who eventually developed BKVN. In contrast, viremia remained positive in one patient with BKVN and disappeared in the second but renal function deteriorated in both of them. Initial viral load was higher in patients who developed BKVN.

CONCLUSION

Reduction of IS is probably an effective therapeutic option to clear viremia and prevent BKVN in viremic renal transplant patients.

Comparison of outcomes with low-dose anti-thymocyte globulin, basiliximab or no induction therapy in pediatric kidney transplant recipients: a retrospective study

It is unclear which induction therapy yields the best outcomes in pediatric kidney transplantation. Retrospective data of 88 children receiving a renal allograft between November 1996 and October 2003 were analyzed. Patients received ATGI (n = 12), BI (n = 29), or NAI (n = 47). The mean ATG dose was 5.1 +/- 2.1 mg/kg. At 12 months, graft survival rates were 91.7%, 100%, and 97.9% for ATGI, BI, and NAI groups, respectively. Acute rejection rates at 12 months were 0 (ATGI), 20.6% (BI), and 10.7% (NAI). The mean GFR for ATGI (42.4 +/- 25.9 mL/min) was lower than for BI (78.3 +/- 27.2 mL/min), and NAI (66 +/- 28.3 mL/min) at 12 months (p < 0.05). One ATGI patient developed CMV pneumonia but none developed post-transplant lymphoproliferative disorder. Although there was no renal allograft survival benefit with either ATGI or BI, relative to NAI, the absence of acute rejection and equivalent rates of viral infections in the higher-risk ATGI recipient group suggests that the treatment strategy is promising. A large prospective study is needed to better define the role of ATGI in pediatric kidney transplantation.

Thymoglobulin and rate of infectious complications after transplantation

Thymoglobulin is used as an induction agent in kidney transplantation, but the optimal dose is not well established. However, its use may be associated with increased infectious complications after transplantation.

METHODS

This retrospective study of 61 high-risk renal recipients of transplants from deceased donors performed between June 2001 and April 2004 included patients treated with thymoglobulin. Patients were divided into two groups according to the total thymoglobulin dose (G1, n = 30, <7 mg/kg; G2, n = 31, >7 mg/kg) and followed for at least 1 year.

RESULTS

Mean recipient age was 43 +/- 14 years; 41% were males; 63% non-Whites. Mean cold ischemia time was 26.3 +/- 7 hours. Mean PRA was 23% (0-100%). Second transplantation was performed in 18 (29.5%) patients. Mean donor age was 42.1 +/- 16 years, and 59% had a cerebral vascular accident as the cause of death. Patient- and death-censored graft survival at 12 months were 86% and 88%, respectively. There were 149 infectious episodes among 47 (78%) patients. The incidence of infection was 1.7 +/- 0.24 infections per patient per year in G1 (lower dose) vs 3.12 +/- 0.23 in G2 (P < .001). Bacterial (0.66 +/- 1.0 vs 1.48 +/- 1.26 infections per patient per year, P = .009) and viral infections (0.9 +/- 0.71 vs 1.41 +/- 0.71; P = .006) were more frequent in the higher dose group.

CONCLUSION

This study suggested that a greater number of infectious episodes were present when the total dose of thymoglobulin was higher than 7 mg/kg.

Basiliximab Versus Rabbit Anti-thymocyte Globulin for Induction Therapy in Patients After Heart Transplantation

BACKGROUND

The use of basiliximab or rabbit anti-thymocyte globulin (RATG) for induction therapy has significantly reduced the incidence of acute rejection episodes post-transplantation. The purpose of this study was to compare the safety and efficacy of basiliximab vs RATG in a population of adult heart transplant recipients.

METHODS

We retrospective analyzed the safety and efficacy of basiliximab compared with RATG among 48 adult heart transplant recipients at our center. Twenty-five patients received basiliximab (20 mg on days 0 and 4 after heart transplantation), and 23 patients received RATG (1.5 mg/kg for 3 days). A standard triple-drug immunosuppression regimen was administered to all patients.

RESULTS

The average biopsy score (ABS) at 1 month was 0.79 +/- 0.18 in the Basiliximab Group vs 0.47 +/- 0.2 in the RATG group (p = 0.023) and at 3 months was 0.75 +/- 0.24 in the Basiliximab Group vs 0.46 +/- 0.12 in the RATG Group (p = 0.032). At 6 months after transplantation, the difference between groups was not statistically significant (0.97 +/- 0.23 vs 0.58 +/- 0.17, p = .14). At 12 months the ABS was 0.85 +/- 0.4 in the Basiliximab Group vs 0.63 +/- 0.15 in the RATG Group (p = 0.12), and the number of episodes of infection was similar in both groups (19 vs 26; p = 0.16). There was no correlation between cumulative cyclosporine doses and rejection. Creatinine clearance levels were not statistically different between groups at baseline and up to 12 months after heart transplantation. Three patients died in the Basiliximab Group, and 2 patients died in the RATG Group.

CONCLUSIONS

Rabbit anti-thymocyte globulin is more effective than basiliximab for prevention of rejection episodes after heart transplantation. Both induction agents provide similar safety profile.

Comparison of two dosages of thymoglobulin used as a short-course for induction in kidney transplantation

Thymoglobulin is used effectively as an induction agent in kidney transplantation, but the optimal dose is not well established. We evaluated the degree and durability of T-cell clearances with two different thymoglobulin regimens in adult kidney transplant recipients (KTR). Seven KTR received a 3-day thymoglobulin-based induction of 1.0 mg/kg/day while nine received 1.5 mg/kg/day, in addition to maintenance immunosuppression. Lymphocyte subsets were monitored for 6 months. Renal function, infections and malignancies were monitored for 24 months. T-cell subsets were significantly lower by day 30 with the thymoglobulin 1.5 mg/kg/day regimen when compared with the 1.0 mg/kg/day regimen; this trend was sustained at 6-month (CD3(+): 438 +/- 254 vs. 1001 +/- 532 cells/mm(3), P = 0.016). Renal function between the two groups was not significantly different at 6- and 24-months post-transplant. One case of BK Virus viremia in the 1.5 mg/kg/day thymoglobulin group was detected. No acute rejection episodes, cytomegalovirus infections, or malignancies were noted in either group. Thymoglobulin induction was efficacious in both groups, but with a significantly sustained T-cell clearance in the 1.5 mg/kg/day regimen. A more profound T-cell clearance within the first 6 months postinduction therapy may translate into a decreased risk of immunological injury and improved long-term outcome after kidney transplantation.

ATG induction therapy: long-term effects on Th1 but not on Th2 responses

Antithymocyte globulin (ATG) induction therapy is associated with an increased long-term risk of infection- and cancer-related death. To analyze long-term effects of ATG induction on lymphocyte function, we prospectively assessed CD4 helper function, B-cell/monocyte and cytokine responses in 84 renal transplant recipients (ATG, n = 44) up to 1 year post-transplant. A PWM-driven allogeneic coculture system was used to assess helper function of CD4+ T cells and T-cell-dependent B-cell responses. SAC I was used for T-cell-independent stimulation of B-cell cultures. In vitro cytokine secretion and serum soluble CD30 (sCD30) were determined by enzyme-linked immunosorbent assay (ELISA). ATG induced a persistent decrease of peripheral blood lymphocyte counts compared with non-ATG treatment because of a predominant decrease of CD4+ T cells (4 months, 1 year; P < 0.0005) which was associated with a decreased CD28 expression (1 year, P = 0.02) and CD4 cell interleukin 2 (IL-2) response (4 months, P < 0.0005). However, Th2 responses (CD4 help, CD4 cell IL-4 and IL-10 responses, sCD30), which proved to be predictive of graft outcome, were not affected, and neither was the secretion of the lymphoma growth factors IL-6 and IL-10 by B cells and monocytes. Our data show that ATG induction therapy in immunological high-risk patients induces a profound long-term decrease in cell counts and Th1 but not Th2 responses of CD4+ T cells which may explain long-term effects on infection and post-transplant lymphoproliferative disease (PTLD) incidence because of inadequate T-cell control.

Beneficial effect of concomitant induction with antilymphoblast globulin, cyclosporine, and steroids on long-term renal allograft outcome

BACKGROUND

The addition of induction therapy with antilymphocytic antibodies to cyclosporine (CsA) based immunosuppression, has reduced acute rejection incidence and improved short-term survivals, but has not had well-established effects on long-term renal transplant survival.

PATIENTS

We analyzed the long-term allograft outcome of patients included in a prospective randomized clinical study conducted in our center 15 years ago by comparing two strategies: (A) horse antilymphoblast globulin (ALG) given at 10 mg/kg on alternate days to a maximum of 6 doses with low-dose CsA started at 8 mg/kg per day and prednisone at 0.25 mg/kg per day, versus (B) CsA started at 15 mg/kg per day and prednisone at 0.5 mg/kg per day. Diabetic and highly sensitized patients (PRA > 70%) were excluded from the study.

RESULTS

The characteristics of the 50 patients enrolled in each group were not different. Although patient survival was not different (88% in group A vs 77% in group B), recipients treated with ALG showed a lower incidence of acute rejection episodes (20% vs 44%, P = .01) and better death-censored renal allograft survival (57% vs 41%, P = .03). Among rejection-free patients, graft survival was 15% higher in group A (60% vs 45%, P = .12). Multivariate Cox regression analysis showed that an acute rejection episode (relative risk [RR]: 2.44, 95% confidence interval [CI] 1.36-4.39; P = .0029) rather than ALG immunosuppression (RR 0.74, 95% CI 0.41-1.33; P = NS) was an independent predictor of death-censored graft survival.

CONCLUSIONS

In summary, we confirmed that concomitant induction therapy with ALG, CsA, and steroids improves long-term renal allograft survival.

Comparison of Induction Based on Continuous vs Discontinuous Administration of Antithymocyte Globulins in Renal Transplant Patients: Efficacy and Long-Term Safety

This retrospective study sought to compare two modes of administration of antithymocyte globulin (RATG) after renal transplantation.

METHODS

Before 1993, group I patients (n = 93) received fixed doses of RATG (1 mg/kg per day) for 8 consecutive days. Thereafter, RATG was either continued at the same dose for 15 days, in cases of delayed graft function, or was infused every other day at the same dose until serum creatinine level became <150 micromol/L. After 1993, group II patients (n = 66) received RATG at full dose (1 mg/kg per day) during the first 3 days and thereafter the doses were adjusted to target a CD2 T-cell count <50/mm3. Both groups received steroids, azathioprine, and cyclosporine. The mean follow-up after transplantation was 117 +/- 31 months in group I and 93 +/- 19 months in group II.

RESULTS

The RATG cumulative dose and consequently cost were significantly higher among group I than group II patients. Long-term patient and graft survival were similar in both groups. The rate of acute graft-rejection episodes was significantly higher among group I than group II patients. At 7 years posttransplantation, the serum creatinine level and creatinine clearance were similar in the two groups. The rate of cytomegalovirus infection, as well as the cumulative incidence of severe infections and cancers were also similar in both groups. Among the cancers, skin neoplasms represented 30% in group I and 26% in group II (P = ns).

CONCLUSION

Adjusting RATG doses according to the CD2 lymphocyte count is safe, and a less expensive than using full doses.

Long-Term Evolution of Lymphocytes Subsets After Induction Therapy Based on Continuous Versus Discontinuous Administration of Anti-Thymocyte Globulins in Renal-Transplant Patients

The aim of our retrospective study was to assess the long-term evolution of lymphocyte subsets after two modes of administration of anti-thymocyte globulin (ATG) after renal transplantation.

METHODS

Before 1993, patients (group I, n = 93) received fixed doses of RATG (1 mg/kg per day) for 8 consecutive days. Thereafter, RATG was either continued at the same dose for 15 days, in cases of delayed graft function, or was infused every other day at the same dose until the serum creatinine level became <150 micromol/L. After 1993, patients (group II, n = 66) received RATG at full dose (1 mg/kg per day) during the first 3 days and, thereafter, doses were adapted to target a CD2 T-cell count <50/mm3. RATG cumulative dose was significantly higher among group I than group II (9.7 +/- 4.5 versus 7.4 +/- 3.2 mg/kg, P = .0002).

RESULTS

In both groups, total lymphocyte and T lymphocyte subset (CD4, CD8, CD2, CD3) counts decreased significantly during the first month after transplantation, increasing slowly between the first month and the third year posttransplantation. Thereafter it rose rapidly, which was greater in group II. At last follow up, total lymphocyte, T lymphocyte subsets and NK cell counts were similar to those observed before transplantation. At all monitoring times, T lymphocyte, B lymphocyte, and NK cell counts were similar in both group, except for the total lymphocyte count at 6 months and CD4 T lymphocyte count at 1 year, which were significantly higher in group II compared to group I.

CONCLUSION

Induction therapy based on continuous or discontinuous administration of ATG is associated with profound depletion of T, B, and NK cells during the first 3 years, followed by a progressive reconstitution of the lymphocyte pool after 5 years.

Sequential protocols using basiliximab versus antithymocyte globulins in renal-transplant patients receiving mycophenolate mofetil and steroids

BACKGROUND

Sequential anti-thymocyte globulins (ATG)/cyclosporine immunosuppression has two main advantages: delayed introduction of the nephrotoxic drug cyclosporine and prevention of acute rejection. Basiliximab, a recently developed chimeric monoclonal antibody that selectively depletes the minor subpopulation of activated T lymphocytes, has been shown to reduce the incidence of acute rejection when used with cyclosporine introduced on day 1.

METHODS

This open, randomized, multicenter study was undertaken to compare the safety and efficacy of ATG versus basiliximab induction therapy (IT) with delayed introduction of cyclosporine for microemulsion (Neoral) in 105 low immunologic risk renal-transplant patients receiving mycophenolate mofetil and steroids.

RESULTS

One-year patient and graft survival rates were 98.1% and 94.2%, respectively, in the basiliximab group (n = 52), and 98.1% and 96.2% in the ATG group (n = 53). The incidence of biopsy-confirmed acute rejection was comparable (basiliximab 9.6%, ATG 9.4%), as were key parameters of renal function, notably serum creatinine levels, time-to-nadir serum creatinine, and the number of patients requiring posttransplantation dialysis (basiliximab 28.8%, ATG 30.2%). However, significantly fewer patients in the basiliximab group experienced cytomegalovirus (CMV) infection, leukopenia, and thrombocytopenia, and this without any significant difference in any other key safety parameters (including the incidences of serum sickness, fever, lymphoma, and infections in general).

CONCLUSIONS

Both ATG and basiliximab, when used for IT in a sequential protocol, are equally effective in terms of graft and patient survival as well as at preventing acute rejection. However, basiliximab is associated with a lower incidence of certain key adverse events, namely CMV infection, leukopenia, and thrombocytopenia.

Two-day induction with thymoglobulin in kidney transplantation: risks and benefits

INTRODUCTION

The aim of this study was to develop an induction protocol to reduce allograft rejection with fewer posttransplant infections and malignancies.

METHODS

In this prospective randomized study, a T- and B-cell depletion protocol, consisting of IV thymoglobulin (ATG 5 mg/kg/d) plus methylprednisolone (500 mg/d) plus azathiopurine (2 mg/kg/d), was on days 0 and 1 after renal transplantation. CyA was introduced at day 3.39 among patients undergoing either primary living related (n = 16) or cadaveric (n = 23) transplants excluding recipients of full-HLA-matched sibling, or five- and six-HLA-matched cadaveric donor kidneys. The adequacy of immunosuppression was evaluated by flow cytometric analysis for total, CD3+ (T-cell), and CD19+ (B-cell) lymphocytes.

RESULTS

The acute rejection rate was 6% and 37/39 patients are alive with functioning grafts at an average follow-up of 14.5 months. The overall patient and graft survival rate was 95%. Their mean creatinine value was 1.27 mg/dL. Six patients (16%) required hospitalization due to serious infections. The two deaths were attributed to septicemia and brain abcess caused by unusual agents, namely, Rhodococcus equi and Sporobolomyces. One patient presented with a cutaneous Kaposi sarcoma in the 11th month posttransplant.

CONCLUSION

A Two-day induction protocol with thymoglobulin yields acceptable acute rejection rates among renal transplants. However, caution is necessary for adverse events, particularly atypical bacterial and fungal infections.

Induction therapy by anti-thymocyte globulin (rabbit) in renal transplantation: a 1-yr follow-up of safety and efficacy

BACKGROUND

Two hundred and forty cadaveric renal transplant recipients given anti-thymocyte globulin (Thymoglobulin) as induction immunotherapy were followed up prospectively to review safety and efficacy.

METHODS

The median number of infusions was 10 [2-21] with a cumulative dose of 8.8 mg/kg [2.0-23.2 mg/kg]. During the fortnight following transplantation, 231 patients (96%) received a calcineurin inhibitor; all patients were given steroids and azathioprine or mycophenolate mofetil. At 1 yr, 60% of patients were on tripletherapy, 38% on bitherapy, and 2% on monotherapy; 20% had discontinued steroids.

RESULTS

Tolerance was excellent with no cases of anaphylaxis. The commonest adverse event was fever (55%). Eighteen patients developed serum sickness on median day 11 [10-14]. Seven patients had thrombocytopenia; six patients had severe neutropenia. All of these adverse events recovered spontaneously. The overall incidence of delayed graft function was 24%. At 1 yr patient and graft survival were 98 and 95%, respectively, and creatinine was 135 +/- 43 micromol/L. Clinically suspected and biopsy-proven acute rejection were observed in 65 patients (27%) and 34 patients (14%), respectively. There were 62 non-cytomegalovirus (CMV) infections (two fatal) and 81 episodes of CMV infections. Eight malignancies were reported; two possibly related to immunosuppression.

CONCLUSIONS

These results demonstrate that anti-thymocyte globulin has a safety profile with good tolerability and excellent efficacy.

The effect of ATG on cytokine and cytotoxic T-lymphocyte gene expression in renal allograft recipients during the early post-transplant period

BACKGROUND

Despite the long history of ATG use, the exact in vivo mechanism of action remains unclear. In the present study, we analyzed the effect of ATG-induction therapy on expression of 10 immunologically relevant genes in the early post-transplant period.

METHODS

Eight renal allograft recipients received post-transplant prophylactic ATG treatment on 10 consecutive days and an additional three patients received treatment on 5, 6, or 7 consecutive days, respectively. Gene expression was measured at the beginning and the end of therapy and normalized to a control gene using Taqman real-time PCR methodology. Results were compared with those of matched control patients. No patients were diagnosed with rejection.

RESULTS

ATG-treated patients showed decreases in the expression of cytotoxic T cell genes perforin (-56%, p = 0.03) and granzyme B (-45%, p = 0.01) and cytokine gene IFN-gamma (-75%, p = 0.005), and significant increases in the expression of cytokine genes IL-7 (550%, p = 0.04), IL-10 (275%, p = 0.01), IL-15 (417%, p = 0.03), TNF-alpha (615%, p = 0.01), and TGF-beta (235%, p = 0.02). No significant changes were observed in the control group, with the exception of a decrease in IL-10 expression (-42%, p = 0.01). There were no significant changes in IL-12 or Fas-L expression in either group.

CONCLUSION

ATG-induced decreases in the expression of IFN-gamma, perforin, and granzyme B and increases in IL-10 and TGF-beta might be considered beneficial to the recipient, whereas increases in the expression of IL-7, IL-15, and TNF-alpha genes might be involved in immunological processes not effected by ATG that may harm the transplant in the long term.

A three-arm study comparing immediate tacrolimus therapy with antithymocyte globulin induction therapy followed by tacrolimus or cyclosporine A in adult renal transplant recipients

BACKGROUND

Induction therapy with antithymocyte globulin (ATG) reduces the incidence of acute rejection after transplantation. A study was undertaken to assess the efficacy and safety of ATG induction on tacrolimus-based and cyclosporine A (CsA)-based therapies compared with immediate tacrolimus triple therapy in kidney transplant recipients.

METHODS

In a 6-month, open-label, randomized, prospective study conducted in 30 European centers, 555 renal transplant patients were randomly assigned to tacrolimus triple therapy (Tac triple, n=185), ATG induction with tacrolimus (ATG-Tac, n=186), or ATG induction with CsA microemulsion (ATG-CsA, n=184); all were combined with azathioprine and corticosteroids. The primary endpoint was incidence and time to first acute rejection episode confirmed by biopsy.

RESULTS

Patient demographics and clinical parameters at baseline were similar. Patient and graft survival rates were similar in all groups. The incidence of clinically apparent acute rejection was significantly higher (P=0.003) for Tac triple (33.0%) compared with ATG-Tac (22.6%) and the incidence for ATG-Tac was significantly lower (P=0.004) than for ATG-CsA (37.0%). The incidences of acute rejection confirmed by biopsy (primary endpoint) were 25.4%, 15.1%, and 21.2% for Tac triple, ATG-Tac, and ATG-CsA, respectively (Tac triple vs. ATG-Tac, P=0.004). The incidences of corticosteroid-resistant acute rejection were 7.0% (Tac triple), 4.8% (ATG-Tac), and 10.9% (ATG-CsA) (ATG-Tac vs. ATG-CsA, P=0.038). In the ATG groups, the incidences of leukopenia, thrombocytopenia, serum sickness, fever, and cytomegalovirus infection were significantly higher (P<0.05).

CONCLUSIONS

Acute rejection was significantly lower in the ATG-Tac group compared with the ATG-CsA and Tac triple groups. Significantly more hematologic and infectious adverse events were observed in both ATG induction groups.

Individualized T cell monitored administration of ATG versus OKT3 in steroid-resistant kidney graft rejection

Acute steroid-resistant rejection episodes are recommended to be treated with set doses of anti-thymocyte globulin (ATG) or anti-CD3 monoclonal antibody (OKT3). Individualized T cell monitoring has been proposed as a tool for dose finding. A randomized study comparing the efficacy and safety of ATG (n = 27) with OKT3 (n = 28) in the treatment of biopsy verified acute steroid-resistant rejection (ASRR) when both drugs were administered on the basis of daily individualized T cell measurements. A drop to below 50 cells/mm3 CD2+ T cells was considered adequate and used to guide the dose of ATG/OKT3. Demographic, clinical and histopathological severities of rejections were equal in the two groups. During the 10 days of T cell monitoring and antibody treatment, 13 patients were in need of dialysis (ATG = 7/OKT3 = 6). Two grafts did not respond to antibody treatment and were lost due to rejection (ATG = 1/OKT3 = 1). There were 26 biopsy verified re-rejections (ATG = 12/OKT3 = 14) within the first 3 months following antibody treatment. Mean serum creatinine (micromol/L) was similar in the two groups (ATG/OKT3: before rejection 157 +/- 72/151 +/- 88, at start of antibody treatment 308 +/- 125/330 +/- 94, end of antibody treatment 254 +/- 122/246 +/- 144 and at follow-up after a mean of 32 months 166 +/- 55 (n = 24)/164 +/- 57(n = 23)). To keep the T cell count below 50 cells/mm3, average dose ATG given was 354 +/- 151 mg (2.3 administrations, range 1-4) and average OKT3 was 32.5 +/- 6.8 mg in 10 doses. In conclusion, individualized T cell monitored administration of ATG and OKT3 is safe and seems as effective as a standard set dose in treatment of ASRR. Tailoring the dose for each individual patient lowers the cost.

Safety, efficacy, and cost analysis of thymoglobulin induction therapy with intermittent dosing based on CD3+ lymphocyte counts in kidney and kidney-pancreas transplant recipients

BACKGROUND

In view of the superior T-cell depletion and prolonged half-life of thymoglobulin, we initiated a protocol to administer thymoglobulin intermittently based on peripheral blood CD3+ lymphocyte counts.

METHODS

In this prospective study, 41 consecutive high-risk cadaver transplant recipients (panel reactive antibody level >30%, repeat transplant recipients, simultaneous pancreas and kidney or pancreas after kidney recipients, prolonged cold-ischemia time, prolonged donor hypotension, non-heart-beating donors) who received thymoglobulin induction therapy were included. The first dose (1.5 mg/kg) of thymoglobulin was administered intraoperatively. CD3+ lymphocyte count in the peripheral blood was determined daily and repeat doses were administered when the CD3+ count was >20 cells/mm3. Calcineurin inhibitors (CI) in low doses were introduced when the allograft function recovered and the serum creatinine level dropped by at least 25% from the pretransplant level. Thymoglobulin treatment was discontinued once therapeutic CI drug levels were achieved. Concomitant immunosuppression consisted of mycophenolate mofetil and prednisone.

RESULTS

The mean individual thymoglobulin dose was 104 mg (1.4 mg/kg), and the total cumulative dose per patient was 318 mg (4.2 mg/kg). Patients received an average of three doses and a mean of six CD3 counts were obtained per patient. Introduction of CI was delayed for an average of 6 days posttransplantation. At a mean follow-up of 340 days, two (4.9%) patients died; three (7.3%) renal allografts and two (18.2%) pancreas allografts were lost. Five (12.2%) patients developed a total of six acute rejection episodes. The mean serum creatinine in the 38 patients with a functioning kidney was 1.47 mg/dl, and the mean blood glucose in the 9 pancreas allograft recipients was 89 mg/dl. Cytomegalovirus (CMV) infection occurred in one (2.4%) patient. No posttransplant lymphoproliferative disorders were seen in this patient cohort. The hospital pharmacy charge for a 100-mg dose of thymoglobulin at this center was $2,165, and the laboratory charge for a single CD3 determination was $70. In this study, the average charges per patient for the total dose of thymoglobulin and six CD3 determinations were $7305. In comparison, the charge for daily administration of 104 mg of thymoglobulin (which was the mean dose) for 6 days (mean time to CI therapy initiation) would be $13,510 and for 10 days (mean time to therapeutic CI levels) would be $22,516. This represents a savings of 46% and 68%, respectively.

CONCLUSIONS

Intermittent thymoglobulin therapy, based on peripheral blood CD3+ lymphocyte counts, is safe and associated with low acute rejection rate in high-risk kidney and kidney-pancreas transplant recipients. A mean of three doses resulted in adequate suppression of CD3+ lymphocytes permitting delayed introduction of CI in low doses until recovery of renal function occurred. When compared to traditional daily administration, intermittent therapy results in significant cost savings and reduces the total cumulative dose of this potent immunosuppressive agent.

CD3 monitoring of antithymocyte globulin therapy in thoracic organ transplantation

BACKGROUND

Antithymocyte globulin is frequently used as a component of induction therapy in thoracic organ transplantation. This study evaluates the utility of monitoring peripheral CD3 lymphocytes to rationally adjust antithymocyte globulin therapy in this patient population.

METHODS

A total of 17 heart and 19 lung transplant recipients received antithymocyte globulin (ATGAM or thymoglobulin) as induction therapy or to treat steroid-resistant acute or chronic rejection. Absolute CD3 counts were maintained between 50 and 100 cells/microl.

RESULTS

With CD3 monitoring, the doses of antithymocyte globulin were reduced from 10-15 mg/kg to 1-5 mg/kg during the course of therapy. The total amount of antithymocyte globulin given to each CD3 monitored patient was reduced by 48%. Dose reduction did not alter the number of acute rejection or infectious episodes, and hematological side effects were infrequent.

CONCLUSION

CD3 monitoring of antithymocyte globulin therapy in thoracic organ recipients reduced the amount of drug received by each patient, while maintaining CD3 counts less than 100 cells/microl.

Induction versus noninduction in renal transplant recipients with tacrolimus-based immunosuppression

BACKGROUND

The aim of this study was to compare the efficacy and safety of induction treatment with antithymocyte globulins (ATG) followed by tacrolimus therapy with immediate tacrolimus therapy in renal transplant recipients.

METHODS

This 12-month, open, prospective study was conducted in 15 centers in France and 1 center in Belgium; 309 patients were randomized to receive either induction therapy with ATG (n=151) followed by initiation of tacrolimus on day 9 or immediate tacrolimus-based triple therapy (n=158). In both study arms, the initial daily tacrolimus dose was 0.2 mg/kg. Steroid boluses were given in the first 2 days and tapered thereafter from 20 mg/day to 5 mg/day. Azathioprine was administered at 1-2 mg/kg per day.

RESULTS

At month 12, biopsy-confirmed acute rejections were reported for 15.2% (induction) and 30.4% (noninduction) of patients (P=0.001). The incidence of steroid-sensitive acute rejections was 7.9% (induction) and 22.2% (noninduction)(P=0.001). Steroid-resistant acute rejections were reported for 8.6% (induction) and 8.9% (noninduction) of patients. A total of nine patients died. Patient survival and graft survival at month 12 was similar in both treatment groups (97.4% vs. 96.8% and 92.1% vs. 91.1%, respectively). Statistically significant differences in the incidence of adverse events were found for cytomegalovirus (CMV) infection (induction, 32.5% vs. noninduction, 19.0%, P=0.009), leukopenia (37.3% vs. 9.5%, P<0.001), fever (25.2% vs. 10.1%, P=0.001), herpes simplex (17.9% vs. 5.7%, P=0.001), and thrombocytopenia (11.3% vs. 3.2%, P=0.007). In the induction group, serum sickness was observed in 10.6% of patients. The incidence of new onset diabetes mellitus was 3.4% (induction) and 4.5% (noninduction).

CONCLUSION

Low incidences of acute rejection were found in both treatment arms. Induction treatment with ATG has the advantage of a lower incidence of acute rejection, but it significantly increases adverse events, particularly CMV infection.