Matched-pair analysis: identification of factors with independent influence on the development of PTLD after kidney or liver transplantation

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.

Belatacept-Based Maintenance Immunosuppression Controls the Post-Transplant Humoral Immune Response in Highly Sensitized Nonhuman Primates

Preexisting donor-specific antibodies (DSA) to MHC antigens increase the risk of antibody-mediated rejection (AMR) in sensitized transplant recipients and reduces graft survival. Pretransplant desensitization with costimulation blockade and proteasome inhibition has facilitated transplantation in our preclinical nonhuman primate (NHP) model. However, long-term graft survival is limited by rebound of DSA after transplantation. In this study, we performed kidney transplants between highly sensitized, maximally MHC-mismatched NHPs (n=14). At kidney transplantation, primates received T cell depletion with rhesus-specific anti-thymocyte globulin (rhATG; n=10) or monoclonal anti-CD4 and anti-CD8 antibodies (n=4). Maintenance immunosuppression consisted of belatacept and tacrolimus (n=5) or belatacept and rapamycin (n=9) with steroids. Rebound of DSA post-kidney transplantation was significantly reduced compared with maintenance immunosuppression with tacrolimus, mycophenolate, and steroids. Protocol lymph node biopsy specimens showed a decrease in germinal center activity, with low frequencies of T follicular helper cells and class-switched B cells after kidney transplantation. Combined belatacept and rapamycin was superior in controlling viral reactivation, enabling weaning of ganciclovir prophylaxis. Tacrolimus was associated with increased morbidity that included cytomegalovirus and parvovirus viremia and post-transplant lymphoproliferative disorder. All primates in the tacrolimus/belatacept group failed discontinuation of antiviral therapy. Overall, belatacept-based immunosuppression increased AMR-free graft survival by controlling post-transplant humoral responses in highly sensitized NHP recipients and should be further investigated in a human clinical trial.

Publication rate and research topics of studies in pediatric kidney transplantation

BACKGROUND

The quality of medical care for pediatric kidney transplant recipients depends on sound evidence from published clinical trials.

METHODS

We examined the publication rate, time to publication, and factors associated with publication of studies in pediatric kidney transplantation registered on ClinicalTrials.gov from 1999 to 2020.

RESULTS

We identified 136 studies with an overall enrollment of 36255 study participants, of which only 58.8% have been published yet. Unpublished studies included data from 14 350 participants. The median time to publication was 25 months (range, 0-117) with a significantly shorter time to publication in more recent years. The most frequently investigated research topic was immunosuppressants (49.3%), followed by perioperative management (11.0%) and infectiology (10.3%). The percentage of published studies was highest for the topic steroid withdrawal (87.5%), followed by infectiology (78.6%), and nutrition, sports and quality of life (71.4%). Studies, which were co-funded by industry, showed a significantly higher 5-year publication rate (p = 0.019).

CONCLUSIONS

In conclusion, nearly half of all studies in pediatric kidney transplantation remain unpublished. Non-publication of studies might lead to a publication bias with a negative impact on clinical decision-making.

Spleen-Restricted Posttransplant Lymphoproliferative Disorder in the First Year After Kidney Transplant - A Case Report

Posttransplant lymphoproliferative disorders (PTLDs) are a feared complication after transplant. They are mostly of B cell origin and are frequently Epstein-Barr virus (EBV)-positive, particularly in early onset PTLD. Later on, non-B and EBV-negative PTLD are increasingly reported. EBV seronegative receptors (particularly when paired with an EBV seropositive donor) together with the net degree of immunosuppression-a concept often difficult to quantify-are the most consistently described risk factors for the development of PTLD. Conversely, its association with a particular immunosuppressive agent or other virus, namely cytomegalovirus (CMV) infection or disease, has been inconsistently reported. We present a challenging case where an EBV negative monomorphic peripheric T-cell lymphoma was diagnosed in the first year after kidney transplant in a patient with a recent history of CMV disease from a resistant strain.

Post-transplant lymphoproliferative disorders (PTLD)-from clinical to metabolic profiles-a single center experience and review of literature

Post-transplant lymphoproliferative disorders (PTLD) are among the most serious complications after solid organ transplantation (SOT). Monomorphic diffuse large B-cell lymphoma (DLBCL) is the most common subtype of PTLD. Historically, outcomes of PTLD have been poor with high mortality rates and allograft loss, although this has improved in the last 10 years. Most of our understanding about PTLD DLBCL is extrapolated from studies in non-PTLD DLBCL, and while several clinical factors have been identified and validated for predicting non-PTLD DLBCL outcomes, the molecular profile of PTLD DLBCL has not yet been characterized. Compartment-specific metabolic reprograming has been described in non-PTLD DLBCL with a lactate uptake metabolic phenotype with high monocarboxylate transporter 1 (MCT1) expression associated with worse outcomes. The aim of our study was to compare the outcomes of PTLD in our transplant center to historic cohorts, as well as study a subgroup of our PTLD DLBCL tumors and compare metabolic profiles with non-PTLD DLBCL. We performed a retrospective single institution study of all adult patients who underwent a SOT between the years 1992-2018, who were later diagnosed with PTLD. All available clinical information was extracted from the patients' medical records. Tumor metabolic markers were studied in a subgroup of PTLD DLBCL and compared to a group of non-PTLD DLBCL. Thirty patients were diagnosed with PTLD following SOT in our center. Median time from SOT to PTLD diagnosis was 62.8 months (IQR 7.6; 134.4), with 37% of patients diagnosed with early PTLD, and 63% with late PTLD. The most common PTLD subtype was DLBCL. Most patients were treated with reduction of their immunosuppression (RIS) including a group who were switched from calcineurin inhibitor (CNI) to mTOR inhibitor based IS, in conjunction with standard anti-lymphoma chemoimmunotherapy. Progression free survival of the PTLD DLBCL cohort was calculated at 86% at 1 year, and 77% at 3 and 5-years, with overall survival of 86% at 1 and 3-years, and 75% at 5 years. Death censored allograft survival in the kidney cohort was 100% at 1 year, and 93% at 3, 5 and 10 years. MCT1 H scores were significantly higher in a subset of the non-PTLD DLBCL patients than in a PTLD DLBCL cohort. Our data is concordant with improved PTLD outcomes in the last 10 years. mTOR inhibitors could be an alternative to CNI as a RIS strategy. Finally, PTLD DLBCL may have a distinct metabolic profile with reduced MCT1 expression compared to non-PTLD DLBCL, but further studies are needed to corroborate our limited cohort findings and to determine if a specific metabolic profile is associated with outcomes.

Course of renal allograft function after diagnosis and treatment of post-transplant lymphoproliferative disorders in pediatric kidney transplant recipients

BACKGROUND

Post-transplant lymphoproliferative disease (PTLD) is a life-threatening complication in renal transplant recipients. Immunomodulatory and chemotherapeutic treatment potentially affect allograft function. The aim of this study was to evaluate graft function of pediatric kidney transplant recipients following diagnosis and standardized treatment of PTLD.

METHODS

Patients were identified from the German Ped-PTLD registry, and data on renal function were retrospectively retrieved from patient charts. For PTLD treatment, immunosuppressive therapy was reduced and all children received rituximab (375 mg/m² ) for up to six doses. Two patients required additional low-dose chemotherapy. Renal allograft function was monitored by consecutive measurements of estimated glomerular filtration rate (eGFR) at defined time points. Follow-up was up to 60 months after PTLD.

RESULTS

Twenty patients were included in this cohort analysis. Median time from transplantation to PTLD was 2.4 years. Histopathology showed monomorphic lesions in 16 and polymorphic in 4 patients. Two patients experienced PTLD relapse after 2 and 14 months. Range-based analysis of variance showed stable allograft function in 17 of 20 patients (85%). Mean eGFR increased during early treatment phase. One patient experienced graft rejection 5.3 years after diagnosis of PTLD. Another patient developed recurrence of primary renal disease (focal-segmental glomerulosclerosis) and lost his renal allograft 3.8 years post-transplant (2.0 years after PTLD diagnosis).

CONCLUSION

Treatment of PTLD with rituximab with or without low-dose chemotherapy in combination with reduced immunosuppression, mostly comprising of an mTOR inhibitor-based, calcineurin inhibitor-free regimen, is associated with stable graft function and favorable graft survival in pediatric renal transplant patients.

Gray Matter Sampling Differences Between Subdural Electrodes and Stereoelectroencephalography Electrodes

Objective: Stereoelectroencephalography (SEEG) has seen a recent increase in popularity in North America; however, concerns regarding the spatial sampling capabilities of SEEG remain. We aimed to quantify and compare the spatial sampling of subdural electrode (SDE) and SEEG implants.

Methods: Patients with drug-resistant epilepsy who underwent invasive monitoring were included in this retrospective case-control study. Ten SEEG cases were compared with ten matched SDE cases based on clinical presentation and pre-implantation hypothesis. To quantify gray matter sampling, MR and CT images were coregistered and a 2.5mm radius sphere was superimposed over the center of each electrode contact. The estimated recording volume of gray matter was defined as the cortical voxels within these spherical models. Paired t-tests were performed to compare volumes and locations of SDE and SEEG recording. A Ripley's K-function analysis was performed to quantify differences in spatial distributions.

Results: The average recording volume of gray matter by each individual contact was similar between the two modalities. SEEG implants sampled an average of 20% more total gray matter, consisted of an average of 17% more electrode contacts, and had 77% more of their contacts covering gray matter within sulci. Insular coverage was only achieved with SEEG. SEEG implants generally consist of discrete areas of dense local coverage scattered across the brain; while SDE implants cover relatively contiguous areas with lower density recording.

Significance: Average recording volumes per electrode contact are similar for SEEG and SDE, but SEEG may allow for greater overall volumes of recording as more electrodes can be routinely implanted. The primary difference lies in the location and distribution of gray matter than can be sampled. The selection between SEEG and SDE implantation depends on sampling needs of the invasive implant.

18F-FDG PET/CT for Evaluation of Post-Transplant Lymphoproliferative Disorder (PTLD)

Post-transplant lymphoproliferative disorders (PTLD) are a spectrum of heterogeneous lymphoproliferative conditions that are serious and possibly fatal complications after solid organ or allogenic hematopoietic stem cell transplantation. Most PTLD are attributed to Epstein-Barr virus reactivation in B-cells in the setting of immunosuppression after transplantation. Early diagnosis, accurate staging, and timely treatment are of vital importance to reduce morbidity and mortality. Given the often nonspecific clinical presentation and disease heterogeneity of PTLD, tissue biopsy and histopathological analysis are essential to establish diagnosis and most importantly, determine the subtype of PTLD, which guides treatment options. Advanced imaging modalities such as ¹⁸F-FDG PET/CT have played an increasingly important role and have shown high sensitivity and specificity in detection, staging, and assessing treatment response in multiple clinical studies over the last two decades. However, larger multicenter prospective validation is still needed to further establish the clinical utility of PET imaging in the management of PTLD. Significantly, new hybrid imaging modalities such as PET/MR may help reduce radiation exposure, which is especially important in pediatric transplant patients.

Post Transplant Lymphoproliferative Disorder risk factors in children: Analysis of a 23-year single-institutional experience

INTRODUCTION

PTLD is the most frequent malignancy following SOT in children and the second most common SOT complication in adults. However, factors determining outcomes in children are poorly understood due to its relative rarity.

METHODS

This study was performed at the University of Florida. Univariate and multivariate analyses were used to identify prognostic factors in pediatric patients diagnosed with PTLD.

RESULTS

We reviewed records of 54 pediatric (younger than 18 years old at diagnosis) patients diagnosed with PTLD from 1994 to 2017. The median follow-up was 28.8 months. The estimated 5-year survival rate was 87.6% (95% CI 74.3-94.2%). Univariate analysis showed that organ transplanted (specifically heart transplant), poor response to initial treatment, allograft rejection, and low Karnofsky score were statistically significant for negative prognostic factors in determining survival. Multivariate analysis determined progression in response to initial treatment and presence of allograft rejection as statistically significant prognostic factors affecting overall survival. We found no statistically significant impact of EBV serological status on PTLD prognosis.

CONCLUSIONS

Disease progression and allograft rejection were strong negative prognostic indicators in our study cohort. Close attention to graft status and development of therapies that protect the graft from rejection while bolstering anti-EBV immunity will be essential to further improving PTLD outcomes in children.

Prophylactic Anti-Cytomegalovirus Hyperimmunoglobulin in Critically Ill Liver Transplant Patients: Impact on Early Immunology and Survival

Background: Anti-cytomegalovirus hyperimmunoglobulin (CMVIg) was shown to provide beneficial immunodulatory properties beyond antiviral efficacies. The aim of this retrospective study was to assess the impact of prophylactic CMVIg treatment on early outcome following liver transplantation (LT) in critically ill patients. Methods: Forty-three cirrhotic patients requiring pre-LT intensive care due to multiorgan failure were analyzed. Twenty-eight patients with enhanced CMV risk (D+/R+; D+/R−; D−/R+) received prophylactic CMVIg for a minimum of 7 days, while 15 patients (D−/R−) did not. Results: Post-transplantation rates of intra-abdominal infections (28% vs. 61.1%; p = 0.03), Epstein–Barr virus infections (0% vs. 33.3%; p = 0.034), allograft rejections (0% vs. 22.2%; p = 0.013) and sepsis-related mortality (4% vs. 27.8%; p = 0.026) were significantly lower, whereas incidence of CMV infections (4% vs. 22.2%; p = 0.066) tended to be lower in the CMVIg subset. In multivariate analysis, only pretransplant elevated serum lactate level (hazard ratio = 34.63; p = 0.009) and absence of CMVIg therapy (hazard ratio = 21.76; p = 0.023) were identified as independent promoters of 3-month mortality. Conclusion: Prophylactic treatment with CMVIg reduces predisposition for severe immunological and septic events and, thereby, early mortality in critically ill liver recipients.

Unbiased data analytic strategies to improve biomarker discovery in precision medicine

Omics technologies promised improved biomarker discovery for precision medicine. The foremost problem of discovered biomarkers is irreproducibility between patient cohorts. From a data analytics perspective, the main reason for these failures is bias in statistical approaches and overfitting resulting from batch effects and confounding factors. The keys to reproducible biomarker discovery are: proper study design, unbiased data preprocessing and quality control analyses, and a knowledgeable application of statistics and machine learning algorithms. In this review, we discuss study design and analysis considerations and suggest standards from an expert point-of-view to promote unbiased decision-making in biomarker discovery in precision medicine.

Different causes of early and late-onset post transplant lymphoproliferative disorder in kidney transplantation patients after 2000

BACKGROUND

The purpose of this study was to analyze the link between PTLD incidence and its occurrence time in patients at a single center in comparable medical environments after 2000.

METHODS

Retrospectively, total 3305 kidney transplantation patients medical data were analyzed. Patients were divided into two groups based on the period from the day of kidney transplantation to the day of PTLD diagnosis. Early-onset was defined as PTLD development within two years after transplantation, whereas all other cases were categorized as late-onset PTLD.

RESULTS

In the early-onset group, young age (0-19 years) was confirmed as a risk factor for PTLD incidence (HR 1.49, p = 0.038). In the late-onset group, history of anti-rejection therapy was confirmed as a risk factor (HR 1.32, p = 0.031). Overall survival rates were not significantly different between the two groups (p = 0.556). Graft survival rates were also not different between the two groups (p = 0.549).

CONCLUSION

When patients with PTLD were classified into early-onset group and late-onset group at two years, overall survival and graft survival were comparable. And patients with early-onset PTLD are more likely to be associated with EBV, the late-onset patients are more likely to be immunosuppressed.