Rabbit antithymocyte globulin induction and risk of post-transplant lymphoproliferative disease in adult and pediatric solid organ transplantation: An update

The impact of induction therapy on the risk of posttransplant lymphoproliferative disorder in adult kidney transplant recipients with donor-recipient serological Epstein-Barr virus mismatch

Posttransplant lymphoproliferative disorder (PTLD) poses a significant concern in Epstein-Barr virus (EBV)-negative patients transplanted from EBV-positive donors (EBV R-/D+). Previous studies investigating the association between different induction agents and PTLD in these patients have yielded conflicting results. Using the Organ Procurement and Transplant Network database, we identified EBV R-/D+ patients >18 years of age who underwent kidney-alone transplants between 2016 and 2022 and compared the risk of PTLD with rabbit antithymocyte globulin (ATG), basiliximab, and alemtuzumab inductions. Among the 6620 patients included, 64.0% received ATG, 23.4% received basiliximab, and 12.6% received alemtuzumab. The overall incidence of PTLD was 2.5% over a median follow-up period of 2.9 years. Multivariable analysis demonstrated that the risk of PTLD was significantly higher with ATG and alemtuzumab compared with basiliximab (adjusted subdistribution hazard ratio [aSHR] = 1.98, 95% confidence interval [CI] 1.29-3.04, P = .002 for ATG and aSHR = 1.80, 95% CI 1.04-3.11, P = .04 for alemtuzumab). However, PTLD risk was comparable between ATG and alemtuzumab inductions (aSHR = 1.13, 95% CI 0.72-1.77, P = .61). Therefore, the risk of PTLD must be taken into consideration when selecting the most appropriate induction therapy for this patient population.

Short-term decreased post transplant lymphoproliferative disorder risk after kidney transplantation using two novel regimens

BACKGROUND

Belatacept is employed alongside calcineurin inhibitor (CNI) therapy to prevent graft rejection in kidney transplant patients who are Epstein-Barr virus (EBV) seropositive. Preliminary data suggested that rates of post-transplant lymphoproliferative disorder (PTLD) were higher in individuals treated with belatacept compared to CNI therapy alone.

METHODS

The records of 354 adults who underwent kidney only transplantation from January 2015 through September 2021 at one medical center were evaluated. Patients underwent treatment with either low-doses of mycophenolate, tacrolimus and sirolimus (B⁰, n = 235) or low-doses of mycophenolate, tacrolimus and belatacept (B¹, n = 119). All recipients underwent induction with antithymocyte globulin and a rapid glucocorticosteroid taper. Relevant donor and recipient information were analyzed and endpoints of PTLD were assessed.

RESULTS

There were no cases of PTLD in either cohort within the study period. Recipients in the belatacept cohort experienced lower estimated glomerular filtration rates at 12 months (B⁰: 67.48 vs. B¹: 59.10, p = 0.0014). Graft failure at 12 (B⁰: 1.28% vs. B¹: 0.84%, p = 1.0) and 24 months (B⁰:2.55% vs. B¹: 0.84%, p = 0.431) were similar. There was no difference in rejection rates at 12 (B⁰: 1.27% vs. B¹: 2.52%, p = 0.408) or 24 months (B⁰: 2.12% vs. B¹: 2.52%, p = 1.000). Both groups had similar rates of malignancy, mortality and CMV/BK viremia.

CONCLUSION

Non-belatacept (MMF, tacrolimus and sirolimus) and belatacept-based (MMF, tacrolimus and belatacept) regimens do not appear to pose any increased risk of early onset PTLD. Both cohorts benefited from low rates of rejection, malignancy, mortality and graft failure. Recipients will continue to be monitored as PTLD can manifest as a long-term complication.

Low dose rabbit antithymocyte globulin is non-inferior to higher dose in low-risk pediatric kidney transplant recipients

BACKGROUND

Currently, there is no consensus among pediatric kidney transplant centers regarding the use and regimen for immunosuppressive induction therapy.

METHODS

In this single center, retrospective cohort study, pediatric kidney transplant recipients transplanted between 1 May 2013 and 1 May 2018 with rabbit antithymocyte globulin (rATG) induction were included. We stratified patients based on immunological risk, with high risk defined as those with repeat transplant, preformed donor specific antibody, current panel-reactive antibodies > 20%, 0 antigen match and/or African-American heritage. Outcome of interest was the incidence of biopsy proven acute rejection by 1 year.

RESULTS

A total of 166 patients met inclusion criteria. Age of patients was 12 years (11 mo-21 y), (median, range), 21.5% received a living donor transplant and 50.6% were female. Low-immunologic-risk patients were divided into 2 groups, those who received the lower cumulative rATG dose of ≤ 3.5 mg/kg (n = 52) versus the higher cumulative dose of > 3.5 mg/kg (n = 47). The median total dose in the lower dose group was 3.1 (IQR 0.3) and 4.4 (IQR 0.8) in the higher dose group, P < 0.001. Rejection rate did not differ significantly between the 2 treatment groups (7/52 vs. 6/47). None in the lower dose group developed BK nephropathy versus 3 in the higher dose group. Graft loss due to BK nephropathy occurred in 1 patient in the higher dose group. Graft loss in the whole cohort at 12 months was a rare event (n = 1) with 99.5% graft survival and 100% patient survival.

CONCLUSIONS

Reduced rATG dosing (≤ 3.5 mg/kg) when compared to higher dosing (> 3.5 mg/kg) is safe and effective in low-risk pediatric kidney transplant recipients without increasing risk of rejection. A higher resolution version of the Graphical abstract is available as Supplementary information.

Malignancy among adult heart transplant recipients following patient-tailored dosing of anti-thymocyte globulin: a retrospective, nested case-control study of individualized dosing

Post-transplant malignancy is diagnosed in approximately 18% of heart transplant patients and is a leading cause of death post-transplant. One modifiable risk factor is the type and amount of immunosuppression received. Contemporary rabbit anti-thymocyte globulin (rATG) dosing strategy using T-cell-guided dosing, and its effect on malignancy in heart transplant patients is unclear. This was a single-center, retrospective chart review of heart transplant recipients receiving rATG for induction. Patients diagnosed with malignancy post-transplant were matched 1:2 to controls using a nested case-control design. The primary endpoint was to determine the relative risk of rATG exposure with the actual incidence of malignancy post-transplant. The secondary endpoint was the impact of maintenance immunosuppression on malignancy risk. Of the 126 patients included in the study, 25 developed malignancy and were matched to 50 control patients. The median cumulative rATG dose in milligrams (mg) between groups was 365 mg in malignancy cases and 480 mg in controls (OR 0.90, 95% CI 0.75-1.08, P = 0.28). In both the univariate and multivariable analysis, there was no statistically significant difference in malignancy risk found with any maintenance immunosuppressant. The results of this study showed that patient-tailored rATG dosing strategies may not be associated with malignancy development as previously thought.

Optimal Immunosuppression Strategy in the Sensitized Kidney Transplant Recipient

Patients with previous sensitization events against anti-human leukocyte antigens (HLA) often have circulating anti-HLA antibodies. Following organ transplantation, sensitized patients have higher rates of antibody-mediated rejection (AMR) compared to those who are non-sensitized. More stringent donor matching is required for these patients, which results in a reduced donor pool and increased time on the waitlist. Current approaches for sensitized patients focus on reducing preformed antibodies that preclude transplantation; however, this type of desensitization does not modulate the primed immune response in sensitized patients. Thus, an optimized maintenance immunosuppressive regimen is necessary for highly sensitized patients, which may be distinct from non-sensitized patients. In this review, we will discuss the currently available therapeutic options for induction, maintenance, and adjuvant immunosuppression for sensitized patients.

Implications of cancer prior to and after heart transplantation

Cancer and cardiovascular disease share many risk factors. Due to improved survival of patients with cancer, the cohort of cancer survivors with heart failure referred for heart transplantation (HT) is growing. Specific considerations include time interval between cancer treatment and HT, risk for recurrence and risk for de novo malignancy (dnM). dnM is an important cause of post-HT morbidity and mortality, with nearly a third diagnosed with malignancy by 10 years post-HT. Compared with the age-matched general population, HT recipients have an approximately 2.5-fold to 4-fold increased risk of developing cancer. HT recipients with prior malignancy show variable cancer recurrence rates, depending on years in remission before HT: 5% recurrence if >5 years in remission, 26% recurrence if 1-5 years in remission and 63% recurrence if <1 year in remission. A myriad of mechanisms influence oncogenesis following HT, including reduced host immunosurveillance from chronic immunosuppression, influence of oncogenic viruses, and the cumulative intensity and duration of immunosuppression. Conversely, protective factors include acyclovir prophylaxis, use of proliferation signal inhibitors (PSI) and female gender. Management involves reducing immunosuppression, incorporating a PSI for immunosuppression and heightened surveillance for allograft rejection. Cancer treatment, including immunotherapy, may be cardiotoxic and lead to graft failure or rejection. Additionally, there exists a competing risk to reduce immunosuppression to improve cancer outcomes, which may increase risk for rejection. A multidisciplinary cardio-oncology team approach is recommended to optimise care and should include an oncologist, transplant cardiologist, transplant pharmacist, palliative care, transplant coordinator and cardio-oncologist.

Heterogeneous Manifestations of Posttransplant Lymphoma in Renal Transplant Recipients: A Case Series

Posttransplant lymphoproliferative disorder (PTLD) occurs in 1% to 3% of adult renal transplant recipients (RTRs). PTLD has a heterogeneous presentation and is often associated with Epstein-Barr virus (EBV) and immunosuppression. We present a descriptive case series of 16 RTRs who demonstrate a variety of PTLD manifestations. Fifty-six percent received rabbit antithymocyte globulin induction, and 37.5% received basiliximab. Maintenance immunosuppression included glucocorticoids, tacrolimus, and mycophenolate mofetil. Median time from transplantation to PTLD diagnosis was 96.5 months. PTLD involved a single site in 44% of RTRs and multiple sites in 56%. PTLD was localized to the gastrointestinal tract in 9 RTRs, in lymph nodes in 9, central nervous system in 4, bone marrow in 3, skin in 3, lungs in 2, perinephric space in 2, mediastinum in 1, and native kidney in 1. PTLD was EBV positive in 8 RTRs, monomorphic/monoclonal in 14, and of B-cell lineage in 13. Three RTRs had T-cell PTLD. Immunosuppressive agents, except glucocorticoids, were discontinued at diagnosis. Treatment was chemotherapy either alone (in 14 RTRs) or in combination with radiation. Complete remission was achieved in 62.5% of RTRs. Renal dysfunction developed in 62.5% of RTRs, and 4 received dialysis. The overall mortality rate was 62.5%, with median time of death 6.5 months after diagnosis. PTLD that was EBV negative and had T-cell involvement presented with aggressive disease and a higher mortality. Clinicians should be aware of the various PTLD manifestations. Early diagnosis and a multidisciplinary approach to treatment is crucial for improved patient outcomes.

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.

Induction therapy in kidney transplant recipients: Description of the practices according to the calendar period from the French multicentric DIVAT cohort

Background

There is extensive literature with comparisons between Anti-Thymocyte Globulin (ATG) and Basiliximab (BSX) as induction therapy in kidney transplant recipients. The purpose of our benchmarking study was to describe the consequences in terms of practices in 6 transplantation centers of a French prospective cohort.

Methods

We included adult patients who received a first or second kidney graft between 2013 and 2019 (n = 4157). We used logistic regressions to identify characteristics associated with the use of ATG or BSX.

Results

Use of ATG between the centers ranged from 41% to 75%. We observed different factors associated with the treatment decision. Compared to a first transplant, performing a second graft was the only factor significantly associated with the choice of ATG in all centers. The AUC ranged from 0.67 to 0.91, indicating that the centers seemed to define their own rules. As a result, for patients with the same low immunological risk, the probability of receiving ATG varied from 7% to 36%. We stratified the analyses according to two periods, from 2013 to 2015 and from 2016 to 2019. A similar heterogeneity was observed, and in some cases ATG indications between the centers were inverted.

Conclusions

The heterogeneity of induction therapy practices did not decrease in France, even if the reated literature is prolific. This illustrates the necessity to improve the literature by using meta-analyses of recent studies stratified by graft and patient profiles.

A multicenter survey on post-transplant lymphoproliferative disorders in pediatric heart transplant recipients: A case for development of consensus guidelines for screening, surveillance, and treatment?

Post-transplant lymphoproliferative disorders (PTLD) are the main malignancy seen after pediatric heart transplant and are a significant cause of morbidity and mortality. Prior to the development of detailed guidelines, we sought to identify trends in screening, diagnosis, and treatment of pediatric PTLD. All Pediatric Heart Transplant Society (PHTS) institutions were surveyed. No identifiable patient information was shared. From 56 PHTS centers, 22 responses were received (39.3%). 100% agree PTLD cannot be diagnosed solely based on elevated Epstein-Barr virus (EBV) load. All respondents routinely screen for EBV by blood PCR, but frequency of screening varies. There was intermediate consensus regarding the use of computed tomography (CT) and/or positron emission tomography (PET) in surveillance management for PTLD. Most centers require a diagnostic biopsy before initiating new treatment for PTLD (14 of 18, 77.8%), but many reduce immune suppression based on elevated EBV without pathologic PTLD (16 of 22, 72.7%). Beyond immune modulation, rituximab is most commonly used (9 of 13, 69.2%). Consultation with oncology is common (17 of 17, 100%), but timing varies widely. Our survey highlights significant elements of agreement and significant practice variation among PHTS institutions regarding pediatric PTLD. Reduction of immune suppression prior to pathologic diagnosis of PTLD is a common management strategy. When this fails, rituximab is used, but is most often reserved until after confirmation of the diagnosis. Oncology subspecialists are commonly involved in these cases. Our findings highlight the need to develop improved guidelines for evaluation and treatment of pediatric PTLD.

Malignancy after lung transplantation

Lung transplantation is an established therapeutic option for selected patients with advanced lung diseases. As early outcomes after lung transplantation have improved, chronic medical illnesses have emerged as significant obstacles to long-term survival. Among them is post-transplant malignancy, currently representing the 2^nd most common cause of death 5–10 years after transplantation. Chronic immunosuppressive therapy and resulting impairment of anti-tumor immune surveillance is thought to have a central role in cancer development after solid organ transplantation (SOT). Lung transplant recipients receive more immunosuppression than other SOT populations, likely contributing to even higher risk of cancer among this group. The most common cancers in lung transplant recipients are non-melanoma skin cancers, followed by lung cancer and post-transplant lymphoproliferative disorder (PTLD). The purpose of this review is to outline the common malignancies following lung transplant, their risk factors, prognosis and current means for both prevention and treatment.

Epstein-Barr virus-positive post-transplant lymphoproliferative disordepresenting as hematochezia and enterobrosis in renal transplant recipients in China: A report of two cases

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) is a rare severe complication after renal transplantation, with an incidence of approximately 0.3%-2.0% in patients undergoing renal transplantation. The clinical manifestations of PTLD are often nonspecific, leading to tremendous challenges in the clinical diagnosis and treatment of PTLD.

CASE SUMMARY

We report two Epstein-Barr virus (EBV)-positive PTLD cases whose main clinical manifestations were digestive tract symptoms. Both of them admitted to our hospital because of extranodal infiltration symptoms and we did not suspect of PTLD until the pathology confirmation. Luckily, they responded well to the treatment of rituximab. We also discuss the virological monitoring, clinical characteristics, diagnosis, and treatment of PTLD.

CONCLUSION

PTLD is a deceptive disease and difficult to diagnose. Once patients are confirmed with PTLD, immune suppressant dosage should be immediately reduced and rituximab should be used as first-line therapy.

Impact assessment and investigation of factors associated with herpesviruses viremia in the first year of renal transplantation

The increased risk for opportunistic infections after a renal transplant requires monitoring of viral infections to avoid future complications. Our goal was to investigate the impact and factors associated with Epstein-Barr virus (EBV), human cytomegalovirus (HCMV) and human herpesvirus type 6 (HHV-6) viremia in renal transplant recipients. Whole blood samples were collected monthly from 82 patients during the first semester and then quarterly up to 1 year after transplantation. EBV, HCMV, and HHV-6 were detected and quantified by TaqMan real-time polymerase chain reaction. The results showed that EBV and HCMV viremia were detected in 32 patients (39% each), while HHV-6 viremia in only 3 patients (3.7%). EBV was significantly associated with age (P = .050), thymoglobuline induction (P = .019), mTOR inhibitor-based therapy (P = .003), and female gender (P = .044). HCMV was significantly associated with basiliximab induction (P = .015), mycophenolate mofetil (MMF)-based therapy (P = .003) and allograft acute rejection (P = .033). Moreover, HCMV-disease was correlated with MMF-based therapy (P = .021) and female gender (P = .003). In conclusion, EBV and HCMV viremia were associated with different immunosuppressive induction and maintenance strategies. Additionally, higher HCMV viremia (> 10 ⁴ copies/mL) was related to acute allograft rejection.

Induction Therapy in Elderly Kidney Transplant Recipients With Low Immunological Risk

BACKGROUND

In nonimmunized patients, similar rejection rates are observed for patients who have undergone thymoglobulin (antithymocyte globulins [ATG]) or basiliximab (BSX) therapy. While ATG may improve delayed graft function, it may also be associated with higher infection rates and malignancy risk. We compared survival and clinical outcomes in elderly recipients with low immunological risk according to their induction therapy.

METHODS

We conducted a multicentric study on nonimmunized patients ≥65 years of age receiving a first kidney transplant between 2010 and 2017. The principal outcome was patient and graft survival. Secondary outcomes were cumulative probabilities of infection, first acute rejection episode, malignancy, de novo donor specific antibody, posttransplant diabetes (PTD), cardiac complications, estimated glomerular filtration rate, and occurrence of delayed graft function. Cox, logistic, or linear statistical models were used depending on the outcome studied, and models were weighted on the propensity scores.

RESULTS

Two hundred and four patients were included in the BSX group and 179 in the ATG group with the average age of 71.0 and 70.5 years, respectively. Patient and graft survival at 3 years posttransplantation were 74% (95% CI, 65%-84%) and 68% (95% CI, 60%-78%) in ATG and BSX group, respectively, without significant difference. Occurrence of PTD was significatively higher in BSX group (23% versus 15%, P = 0.04) due to higher trough levels of Tacrolimus on month 3 (9.48 versus 7.30 ng/mL, P = 0.023). There was no difference in other evaluated outcomes.

CONCLUSIONS

In elderly recipients, ATG does not lead to poorer outcomes compared with BSX and could permit lower trough levels of Tacrolimus, thus reducing occurrence of PTD.

Incidence, Risk Factors, Clinical Management, and Outcomes of Posttransplant Lymphoproliferative Disorder in Kidney Transplant Recipients

BACKGROUND

Posttransplant lymphoproliferative disorder (PTLD) is a severe complication after kidney transplantation. This study examined the incidence, risk factors, clinical management, and outcomes of PTLD in a cohort of kidney transplant recipients.

DESIGN

This single-center cohort study included 1642 patients transplanted from January 1, 2000, to December 31, 2012, with follow-up until December 31, 2013. The incidence and risk factors for PTLD were examined using a Cox proportional hazards model. A Cox model was also used to assess the association of PTLD and graft outcomes.

RESULTS

Sixteen recipients developed PTLD over follow-up. The incidence rate was 0.18 (95% confidence interval [CI]: 0.11-0.29) cases per 100 person-years. Four were from Epstein-Barr virus (EBV) mismatched (D+/R-) transplants and 12 from EBV-positive recipients (R+). Recipients with D+/R- matches were at a significantly higher risk of developing PTLD than R+ (hazard ratio [HR]: 7.52 [95% CI: 2.42-23.32]). Fifteen cases had immunosuppression reduced, 11 cases were supplemented with rituximab or ganciclovir, 6 cases required chemotherapy or radiation, and 6 cases had tumors excised. By the end of follow-up, 6 patients went into remission, 5 returned to chronic dialysis, and 5 patients died. Patients with PTLD were significantly more likely to have total graft failure (return to chronic dialysis, preemptive retransplant, or death with graft function) than patients without PTLD (HR: 3.41 [95% CI: 1.72-6.78).

DISCUSSION

Epstein-Barr virus mismatch continues to be a strong risk factor for developing PTLD after kidney transplantation. Recipients with PTLD have a poor prognosis, as the optimal management remains to be elucidated.

State-of-the-art immunosuppression protocols for pediatric renal transplant recipients

Immunosuppressive protocols used in pediatric kidney transplantation have changed substantially within the last decade. Many transplant centers now focus on the use of tacrolimus and mycophenolate mofetil in combination with early steroid withdrawal, frequently combined with antibody induction therapy. However, this approach is mainly based on treatment efficacy and-compared to other immunosuppressive regimens used in this context-leads to higher rates of viral infections in patients. In this review I assess data from prospective, interventional trials of immunosuppressive therapy in pediatric kidney transplantation. However, since there is a paucity of randomized controlled trials, I also describe the results of studies with weaker designs. The advantages and disadvantages of different immunosuppressive strategies are discussed. Within this framework I suggest ideas for individualized immunosuppressive regimens based on different stratificators that could effect a change from a 'one size fits all' to a tailored approach for initial and maintenance immunosuppressive therapy after renal transplantation in the pediatric setting.

Immunosuppressive therapy with rabbit antithymocyte globulin therapy for acquired aplastic anemia: a multi-institutional retrospective study in Japanese adult patients

We retrospectively analyzed efficacy and safety of therapy with rabbit antithymocyte globulin (rATG) in combination with cyclosporine A (CsA) in 30 Japanese adult patients with acquired aplastic anemia (AA) in the Kyoto Clinical Hematology Study Group. The median observation period was 31 months and the median age of the patients was 54 years. The objective response rates (ORRs) to rATG plus CsA increased over time until 18 months after the start of treatment; the rate of achievement of better than partial response at 18 months was 66.7%. The 2-year overall survival (OS) rate was 79% in all patients. In eight patients aged ≥ 75 years old, the ORR was 62.5% and the 2-year OS rate of 50% was not significantly inferior to that in patients aged ≤ 74 years old. The overall mortality rate was 16.7% in our cohort, while the mortality rate in patients aged ≥ 75 years old was 37.5%, which was higher than that in patients aged ≤ 74 years old (9.1%), although the difference was not statistically significant. Collectively, rATG combined with CsA is an effective and feasible treatment for AA, while patients should be appropriately selected.

Does Rabbit Antithymocyte Globulin (Thymoglobuline®) Have a Role in Avoiding Delayed Graft Function in the Modern Era of Kidney Transplantation?

Delayed graft function (DGF) increases the risk of graft loss by up to 40%, and recent developments in kidney donation have increased the risk of its occurrence. Lowering the risk of DGF, however, is challenging due to a complicated etiology in which ischemia-reperfusion injury (IRI) leads to acute tubular necrosis. Among various strategies explored, the choice of induction therapy is one consideration. Rabbit antithymocyte globulin (rATG [Thymoglobuline]) has complex immunomodulatory effects that are relevant to DGF. In addition to a rapid and profound T-cell depletion, rATG inhibits leukocyte migration and adhesion. Experimental studies of rATG have demonstrated attenuated IRI-related tissue damage in reperfused tissues, consistent with histological evidence from transplant recipients. Starting rATG intraoperatively instead of postoperatively can improve kidney graft function and reduce the incidence of DGF. rATG is effective in preventing acute rejection in kidney transplant recipients at high immunological risk, supporting delayed calcineurin inhibitor (CNI) introduction which protects the graft from early insults. A reduced rate of DGF has been reported with rATG (started intraoperatively) and delayed CNI therapy compared to IL-2RA induction with immediate CNI in patients at high immunological risk, but not in lower-risk patients. Overall, induction with rATG induction is the preferred choice for supporting delayed introduction of CNI therapy to avoid DGF in high-risk patients but shows no benefit versus IL-2RA in lower-risk individuals. Evidence is growing that intraoperative rATG ameliorates IRI, and it seems reasonable to routinely start rATG before reperfusion.

Anti-thymocyte globulins in kidney transplantation: focus on current indications and long-term immunological side effects

Antithymocyte globulins (ATGs) are part of the immunosuppression arsenal currently used by clinicians to prevent or treat acute rejection in solid organ transplantation. ATG is a mixture of non-specific anti-lymphocyte immunoglobulins targeting not only T cell subsets but also several other immune and non-immune cells, rendering its precise immunoglobulin composition difficult to appreciate or to compare from one preparation to another. Furthermore, several mechanisms of action have been described. Taken together, this probably explains the efficacy and the side effects associated with this drug. Recent data suggest a long-term negative impact on allograft and patient outcomes, pointing out the need to better characterize the potential toxicity and the benefit-risk balance associated to this immunosuppressive therapy within large clinical trials.

Rabbit anti-human thymocyte immunoglobulin for the rescue treatment of chronic antibody-mediated rejection after pediatric kidney transplantation

BACKGROUND

Chronic antibody-mediated rejection (cAMR) is the leading cause of late kidney graft loss, but current therapies are often ineffective. Rabbit anti-human thymocyte immunoglobulin (rATG) may be helpful, but its use is virtually undocumented.

METHODS

Data were analyzed retrospectively from nine pediatric kidney transplant patients with cAMR were treated with rATG (1.5 mg/kg × 5 days) at our center after non-response to pulsed prednisolone, intravenous immunoglobulin, rituximab, and increased immunosuppressive intensity (including switching to belatacept in some cases), with or without bortezomib.

RESULTS

The median time from diagnosis to cAMR was 179 days. rATG was started 5-741 days after diagnosis. Median estimated glomerular filtration rate (eGFR) increased from 40 mL/min/1.73 m² when rATG was started to 62 mL/min/1.73 m² 9 months later (p = 0.039). Four patients showed substantially higher eGFR after 9 months and 2 patients showed a small improvement; eGFR continued to decline in 3 patients after starting rATG. No grafts were lost during follow-up. At last follow-up, donor-specific antibodies (DSAs) were no longer detectable in 4 out of 8 patients for whom data were available, median fluorescence intensity had decreased substantially in 1 out of 8 patients; anti-HLA DQ DSAs persisted in 2 out of 8 patients. No adverse events with a suspected relation to rATG, including allergic reactions, leukocytopenia or infections, were observed in any of the patients.

CONCLUSIONS

In this small series of patients, rATG appears a promising treatment for unresponsive cAMR. Further evaluation, including earlier introduction of rATG, is warranted.

Daunting but Worthy Goal: Reducing the De Novo Cancer Incidence After Transplantation

Solid-organ transplant recipients are at increased risk of developing de novo malignancies compared with the general population, and malignancies become a major limitation in achieving optimal outcomes. The prevention and the management of posttransplant malignancies must be considered as a main goal in our transplant programs. For these patients, immunosuppression plays a major role in oncogenesis by both impairement of immunosurveillance, enhancement of chronic viral infection, and by direct prooncogenic effects. It is essential to manage the recipient with a long-term adapted screening program beginning before transplantation to use a prophylaxis to decrease infection-related cancer, to propose a viral monitoring, and to modulate the immunosuppression toward lower doses especially for calcineurin inhibitors. Indeed, strategies to induce tolerance or to allow a dramatic reduction of the immunosuppression burden are the more promising approaches for the reduction of the posttransplant malignancies.

Induction Therapy for Kidney Transplant Recipients: Do We Still Need Anti-IL2 Receptor Monoclonal Antibodies?

Induction therapy with antilymphocyte biological agents is widely used after kidney transplantation, most commonly T lymphocyte-depleting rabbit-derived antithymocyte globulin (rATG) or an IL-2 receptor antagonist (IL2RA). Early randomized trials showed that rATG or IL2RA induction reduces early acute rejection, prompting recommendations by Kidney Disease Improving Global Outcomes that IL2RA induction be used routinely in first-line therapy after kidney transplantation, with lymphocyte-depleting induction reserved for high-risk cases. These studies, however, mainly used outdated maintenance regimens. No large randomized trial has examined the effect of IL2RA or rATG induction versus no induction in patients receiving tacrolimus, mycophenolic acid and steroids. With this triple maintenance therapy, the addition of induction may achieve an absolute risk reduction for acute rejection of only 1-4% in standard-risk patients without improving graft or patient survival. In contrast, rATG induction lowers the relative risk of acute rejection by almost 50% versus IL2RA in patients with high immunological risk. These recent data raise questions about the need for IL2RA in kidney transplantation, as it may no longer be beneficial in standard-risk transplantation and may be inferior to rATG in high-risk situations. Updated evidence-based guidelines are necessary to support clinicians deciding whether and what induction therapy is required for their transplant patients today.

Acute Rejection Rates and Graft Outcomes According to Induction Regimen among Recipients of Kidneys from Deceased Donors Treated with Tacrolimus and Mycophenolate

BACKGROUND AND OBJECTIVES

IL-2 receptor antagonist (IL2-RA) is recommended as a first-line agent for induction therapy in renal transplantation. However, this remains controversial in deceased donor renal transplantation (DDRT) maintained on tacrolimus (TAC)/mycophenolic acid (MPA) with or without steroids.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied the United Network for Organ Sharing Registry for patients receiving DDRT from 2000 to 2012 maintained on TAC/MPA at transplantation hospital discharge (n=74,627) to compare outcomes of IL2-RA and other induction agents. We initially divided the cohort into two groups on the basis of steroid use at the time of discharge: steroid (n=59,010) versus no steroid (n=15,617). Each group was stratified into induction categories: IL2-RA, rabbit antithymocyte globulin (r-ATG), alemtuzumab, and no induction. The main outcomes were incidence of acute rejection within the first year and overall graft failure (defined as graft failure and/or death) post-transplantation. Propensity score (PS), specifically inverse probability of treatment weight, analysis was used to minimize selection bias caused by nonrandom assignment of induction therapies.

RESULTS

Median (25th, 75th percentiles) follow-up times were 3.9 (1.1, 5.9) and 3.2 (1.1, 4.9) years for steroid and no steroid groups, respectively. Acute rejection within the first year and overall graft failure within 5 years of transplantation were more common in the no induction category (13.3%; P<0.001 and 28%; P=0.01, respectively) in the steroid group and the IL2-RA category (11.1%; P=0.16 and 27.4%; P<0.001, respectively) in the no steroid group. Compared with IL2-RA, PS-weighted and covariate-adjusted multivariable logistic and Cox analyses showed that outcomes in the steroid group were similar among induction categories, except that acute rejection was significantly lower with r-ATG (odds ratio [OR], 0.68; 95% confidence interval [95% CI], 0.62 to 0.74). In the no steroid group, compared with IL2-RA, odds of acute rejection with r-ATG (OR, 0.80; 95% CI, 0.60 to 1.00) and alemtuzumab (OR, 0.68; 95% CI, 0.53 to 0.88) were lower, and r-ATG was associated with better graft survival (hazard ratio, 0.86; 95% CI, 0.75 to 0.99).

CONCLUSIONS

In DDRT, compared with IL2-RA induction, no induction was associated with similar outcomes when TAC/MPA/steroids were used. r-ATG seems to offer better graft survival over IL2-RA in steroid avoidance protocols.

Induction by anti-thymocyte globulins in kidney transplantation: a review of the literature and current usage

Context: Preventing acute rejection (AR) after kidney transplantation is of utmost importance because an AR can have a negative impact on long-term allograft survival.

Evidence Acquisition: Directory of Open Access Journals (DOAJ), Google Scholar, PubMed, EBSCO, and Web of Science have been searched.

Results: At the moment this can be done by using rabbit anti-thymocyte globulins (rATGs) as an induction therapy. However, because rATGs are associated with some deleterious side-effects, such as the opportunistic infections cytomegalovirus (CMV) and de novo post-transplant cancer, it is very important they are used optimally, i.e., at minimal doses that avoid many side-effects but still retain optimal treatment efficacy. Recent data show that the risk of CMV infection can be minimized using tacrolimus plus everolimus, and not tacrolimus plus mycophenolic acid, as the maintenance immunosuppression. The use of rATG is particularly valuable in; (a) sensitized patients; (b) in recipients from an expanded-criteria donor, thus enabling the introduction of calcineurin inhibitors at reduced doses; and (c) for patients where steroid avoidance is contemplated. However, we also need to consider that rATG may increase the risk of de novo cancer, even though recent data indicate this is unlikely and that any risk can be reduced by using mammalian target of rapamycin (mTOR) inhibitors instead of mycophenolic acid combined with low-dose calcineurin inhibitors.

Conclusions: Even though rATGs do not improve long-term kidney-allograft survival, they may help reduce calcineurin-inhibitor dosage during the early post-transplant period and minimize the risk of AR.