Clinical Validation of an Immune Quiescence Gene Expression Signature in Kidney Transplantation

Background

Despite advances in immune suppression, kidney allograft rejection and other injuries remain a significant clinical concern, particularly with regards to long-term allograft survival. Evaluation of immune activity can provide information about rejection status and help guide interventions to extend allograft life. Here, we describe the validation of a blood gene expression classifier developed to differentiate immune quiescence from both T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR).

Methods

A five-gene classifier (DCAF12, MARCH8, FLT3, IL1R2, and PDCD1) was developed on 56 peripheral blood samples and validated on two sample sets independent of the training cohort. The primary validation set comprised 98 quiescence samples and 18 rejection samples: seven TCMR, ten ABMR, and one mixed rejection. The second validation set included eight quiescence and 11 rejection samples: seven TCMR, two ABMR, and two mixed rejection. AlloSure donor-derived cell-free DNA (dd-cfDNA) was also evaluated.

Results

AlloMap Kidney classifier scores in the primary validation set differed significantly between quiescence (median, 9.49; IQR, 7.68-11.53) and rejection (median, 13.09; IQR, 11.25-15.28), with P<0.001. In the second validation set, the cohorts were statistically different (P=0.03) and the medians were similar to the primary validation set. The AUC for discriminating rejection from quiescence was 0.786 for the primary validation and 0.800 for the second validation. AlloMap Kidney results were not significantly correlated with AlloSure, although both were elevated in rejection. The ability to discriminate rejection from quiescence was improved when AlloSure and AlloMap Kidney were used together (AUC, 0.894).

Conclusion

Validation of AlloMap Kidney demonstrated the ability to differentiate between rejection and immune quiescence using a range of scores. The diagnostic performance suggests that assessment of the mechanisms of immunologic activity is complementary to allograft injury information derived from AlloSure dd-cfDNA. Together, these biomarkers offer a more comprehensive assessment of allograft health and immune quiescence.

Comparing the pharmacokinetics of extended-release tacrolimus (LCP-TAC) to immediate-release formulations in kidney transplant patients

INTRODUCTION

One of the most commonly used immunosuppressants in organ transplant, tacrolimus exhibits wide interpatient and intrapatient variability and narrow therapeutic index that necessitates routine concentration monitoring and dosage adjustments. Availability of modified -release tacrolimus products offer once-daily dosing options. The objective of this review is to highlight and compare available pharmacokinetic (PK) data of extended-release tacrolimus tablets (LCP-TAC) to immediate-release tacrolimus (IR-TAC) in kidney transplant recipients.

AREAS COVERED

A review of the literature was performed using PubMed and Embase search to identify relevant articles evaluating PK data for LCP-TAC compared to IR-TAC in kidney transplant patients including special populations.

EXPERT OPINION

LCP-TAC's unique PK profile may be more favorable than IR-TAC. While the clinical impact of these PK differences have not been established, several outcomes are being evaluated in ongoing studies. Results of these studies will add information incrementally to care for kidney transplant patients. Larger prospective studies evaluating kidney and patient survival differences are needed but it is unlikely that they will be conducted. Given that the patent exclusivity of LCP-TAC for the next several years and imminent loss of exclusivity of PR-TAC, our opinion is the use of LCP-TAC will be increasing, especially in Europe.

Outcomes of small pediatric donor kidney transplants according to donor weight

A small pediatric deceased donor (SPD) weight cutoff whether to transplant as en bloc (EB) or single pediatric (SP) kidney is uncertain. Using UNOS/OPTN data (2000-2019), 27 875 SPDs were divided by (i) EB (11.4%) or SP (88.6%) and (ii) donor weight [≤10 (5.4%), >10-15 (8.3%), >15-18 (3.7%), >18-20 (2.9%), and >20 kg (79.7%)]. SP >20 kg and adult deceased donors (grouped by Kidney Donor Profile Index, KDPI, <30, 30-85, and >85) were used as references. The primary outcome was 10-year graft failure. In SP <10 kg, the hazard ratio (HR) for overall graft failure was 1.64 (1.38-2.20) compared with EB <10 kg, and 1.45 (1.18-1.80) compared with SP >20 kg. In SP >10-15 kg, HR was 1.31 (1.12-1.54) compared with EB >10-15 kg, and 1.04 (0.91-1.18) compared with SP >20 kg. In SP >15 kg, the risk was the same as SP >20 kg. Ten-year overall graft survival of SP 12 kg was comparable to SP >20 kg (62% vs. 57%). Ten-year death censored graft failure of SP >10-15 kg (70%) and SP >15-18 kg (70%) was like the adult donors with KDPI 30-85 (67%). In conclusion, we recommend single kidney transplants from SPDs with weight >12 kg to adult recipients in centers with experience in SPD transplants to optimize organ utilization.

Association between ethnicity and kidney transplant waitlist outcomes beyond estimated post-transplant survival score

White kidney transplant candidates have the highest pre-transplant mortality rate compared to other ethnicities. The reason for a higher mortality rate is not well-understood. Estimated post-transplant survival (EPTS) score has been used to predict patient survival after transplant and may be associated with pre-transplant survival. First-time kidney transplant candidates listed between 2015 and 2018 were identified from the Organ Procurement Transplantation Network database. Individuals listed for multiple organs, at multiple centers, and age <18 years were excluded. We examined the impact of ethnicity on waitlist mortality and delisting. A total of 114 806 candidates were included. The study population was categorized into four groups which were 43% white, 28% Black, 19.2% Hispanic, and 9.8% "other ethnicities." At 5.2 years, the cumulative incidences of death and delist were 32%, 31%, 29%, and 26%, respectively. Compared to whites, adjusted subdistribution hazard ratio (aSHR) for death and delist among Black, Hispanics, and "other ethnicities" were 0.92 (95% CI 0.89-0.95), 0.89 (95% CI 0.85-0.91), and 0.76 (95% CI 0.72-0.80) after adjustment by EPTS along with other factors, respectively. After adjusting for EPTS score along with additional confounding factors and functional status at initial listing, white ethnicity was independently associated with an increased risk for death and delist.

Immunosuppression Considerations for Older Kidney Transplant Recipients

PURPOSE OF REVIEW

While kidney transplantation improves the long-term survival of the majority of patients with end-stage kidney disease (ESKD), age-related immune dysfunction and associated comorbidities make older transplant recipients more susceptible to complications related to immunosuppression. In this review, we discuss appropriate management of immunosuppressive agents in older adults to minimize adverse events, avoid acute rejection, and maximize patient and graft survival.

RECENT FINDINGS

Physiological changes associated with senescence can impact drug metabolism and increase the risk of posttransplant infection and malignancy. Clinical trials assessing the safety and efficacy of immunosuppressive agents in older adults are lacking. Recent findings from U.S. transplant registry-based studies suggest that risk-adjusted death-censored graft failure is higher among older patients who received antimetabolite avoidance, mammalian target of rapamycin inhibitor (mTORi)-based, and cyclosporine-based regimens. Observational data suggest that risk-adjusted mortality may be increased in older patients who receive mTORi-based and cyclosporine-based regimens but lower in those managed with T-cell induction and maintenance steroid avoidance/withdrawal.

SUMMARY

Tailored immunosuppression management to improve patient and graft survival in older transplant recipients is an important goal of personalized medicine. Lower intensity immunosuppression, such as steroid-sparing regimens, appear beneficial whereas mTORi- and cyclosporine-based maintenance are associated with greater potential for adverse effects. Prospective clinical trials to assess the safety and efficacy of immunosuppression agents in older recipients are urgently needed.

Efficacy and Safety of Once-Daily LCP-Tacrolimus Versus Twice-Daily Immediate-Release Tacrolimus in Adult Hispanic Stable Kidney Transplant Recipients: Sub-Group Analysis from a Phase 3 Trial

BACKGROUND The pharmacokinetics and metabolism of tacrolimus, an immunosuppressant commonly used to prevent transplant rejection, can differ in specific subpopulations. This analysis examined treatment outcomes and safety of immediate-release tacrolimus (IR-Tac) and LCP-tacrolimus (LCPT) in stable Hispanic kidney transplant recipients. MATERIAL AND METHODS This was a post hoc analysis of clinical trial data from Hispanic adult stable kidney transplant recipients randomized to remain on IR-Tac or convert from IR-Tac to a reduced dose of LCPT (NCT00817206). Composite treatment failure was evaluated at 12 months. Estimated glomerular filtration rate and tacrolimus trough concentrations were evaluated over 12 months. RESULTS Fifty-five stable (LCPT n=26, IR-Tac n=29) kidney transplant recipients who self-identified as Hispanic or Latino were included in this analysis. Composite treatment failure occurred in 1 patient (4%) who converted to LCPT and 1 (3%) who remained on IR-Tac. The estimated glomerular filtration rate was stable over time and similar in the 2 treatment groups (P=0.08). Tacrolimus trough levels for both groups were similar over time in the 2 treatment groups (P=0.98). Treatment-emergent adverse events were similar in patients who converted to LCPT and in those who remained on IR-Tac. CONCLUSIONS Efficacy and safety were similar in Hispanic kidney transplant recipients who converted from IR-Tac to LCPT and in those remaining on IR-Tac.

Impact of donor obesity on allograft outcomes after kidney transplantation adjusted for kidney donor profile index - a national cohort study

Obesity in deceased kidney donors is a known risk factor for poor allograft outcomes. The Kidney Donor Profile Index (KDPI) has been introduced to predict graft survival in deceased donor kidney transplantation (DDKT). Obesity, however, is not included in KDPI. We study the impact of donor obesity on DDKT outcomes after adjusting for organ quality by KDPI. The Organ Procurement Transplantation Network/United Network for Organ Sharing (OPTN/UNOS) data of DDKT from 2005 to 2017, with donor BMI ≥ 18.5 kg/m² and weight >80 kg were included. There was a total of 66 382 DDKTs with 10 917 death-censored graft failures. For KDPI ≤ 30%, the 10-year death-censored graft survival (DCGS) rates among donor BMI < 30, 30-35, 35-40, 40-45 and ≥45 kg/m² groups were 75.9%, 75.4%, 76.1%, 74.9% and 79.6%, respectively. For KDPI > 30%, 10-year DCGS rates were 67.5%, 66.1%, 65.9%, 62.6% and 63.2%, respectively. After adjusting for known confounding factors including KDPI, donor obesity was not independently associated with an increased risk for graft failure. In DDKT with donor weight >80 kg, donor obesity was not associated with a lower long term DCGS compared to non-obesity when KDPI ≤ 30%.

Leukocyte transcriptome indicators of development of infection in kidney transplant recipients

After kidney transplantation, infection and death are important clinical complications, especially for the growing numbers of older patients with limited resilience to withstand adverse events. Evaluation of changes in gene expression in immune cells can reveal the underlying mechanisms behind vulnerability to infection. A cohort of 60 kidney transplant recipients was evaluated. Gene expression in peripheral blood mononuclear cells 3 months after kidney transplantation was analyzed to compare differences between patients with infection and those who were infection-free in the first-year post-transplant. Pro-inflammatory genes such as IL1B, CCL4, and TNF were found to be downregulated in post-transplant PBMC from patients who developed infection. In contrast, genes involved in metabolism, HLA genes, and transcripts involved in type I interferon innate antiviral responses were found to be upregulated. Promoter-based bioinformatic analyses implicated increased activity of interferon regulatory factors, erythroid nuclear factor (E2), and CCAAT-enhancer-binding protein (C/EBP) in patients who developed infections. Differential patterns of gene expression were observed in patients who developed infection after kidney transplantation, with patterns distinct from changes associated with patient age, suggesting possible mechanisms behind vulnerability to infection. Assessment of gene expression in blood may offer an approach for patient risk stratification and monitoring after transplantation.

Early cytomegalovirus DNAemia and antiviral dose adjustment in high vs intermediate risk kidney transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection continues to negatively affect outcomes for solid organ transplant recipients, despite the advent of strategies for preemptive surveillance and prophylaxis. The impact is especially great for CMV seronegative recipients of donor seropositive organs, who typically lack the ability to control CMV infection at the time of transplantation.

METHODS

We reviewed episodes of CMV DNAemia in a modern cohort of kidney transplant recipients over a 3-year period at a high-volume transplant center to investigate the frequency of DNAemia during antiviral prophylaxis.

RESULTS

Despite receipt of antiviral prophylaxis per current guidelines, 75 cases of CMV DNAemia were observed in the first 100 days after transplantation. For high risk patients, median time to DNAemia was 75 days after transplantation, and the majority of patients had experienced dose-reduction of valganciclovir due to renal insufficiency. Review of CMV seropositive intermediate risk patients demonstrated DNAemia occurring earlier after transplantation compared with high risk patients with a median time of 64 days (P = .029). The impact of valganciclovir dose adjustment was less notable in the intermediate risk group.

CONCLUSIONS

Guidelines recommend beginning routine surveillance for CMV after the completion of antiviral prophylaxis. Our findings suggest that closer monitoring may be beneficial, especially for high risk patients at risk for DNAemia. Patients requiring dose adjustment of valganciclovir due to renal insufficiency may be at increased risk for CMV DNAemia. Improved methods for CMV prophylaxis and evaluation of immunologic risk for CMV DNAemia and disease are needed to improve patient outcomes after kidney transplantation.

Listing Malignant Melanoma Patients for Renal Transplantation

BACKGROUND

Melanoma is an immune responsive malignancy and the need for immunosuppression for successful transplantation may lead to recurrent disease. The recommended waiting time is unknown with various groups recommending anywhere from no wait to 5 years.

METHODS

In this single-center, retrospective observational study all kidney transplant recipients' charts from 1991 to 2015 were reviewed for a diagnosis of melanoma before transplantation. The charts were reviewed for the clinical characteristics of melanoma pre transplantation, induction immunosuppression, maintenance immunosuppression, graft function, death, and recurrence of melanoma.

RESULTS

Thirteen patients with a history of melanoma underwent kidney transplantation during this period. Recipients had been in remission for an average of 7.0 years (range, 10 months to 20 years, median 6 years). Approximately 61.5% received a living donor transplant, antithymocyte globulin was administered in 23.1% of recipients, and the remaining 76.9% received basiliximab. Melanoma recurred in 1 patient (7.7%). Maintenance immunosuppression varied, but only 2 patients remained on standard triple therapy with prednisone, calcineurin inhibitor, and antimetabolite therapy. Average follow-up time since transplant was 7.5 years, with 1 patient death 9 years post transplant from sepsis.

CONCLUSION

In conclusion, with our center demonstrates safety of kidney transplantation in patients with a prior history of localized melanoma and shorter waiting time. In malignant melanoma stage 0 and 1, waiting the recommended 5 years from the time of remission to kidney transplantation should be reconsidered.

Spectrum of Coronavirus Disease 2019 Outcomes in Kidney Transplant Recipients: A Single-Center Experience

PURPOSE

We reviewed the clinical experience of kidney transplant recipients diagnosed with severe acute respiratory syndrome coronavirus 2 infection in order to understand the impact of the current coronavirus disease 2019 (COVID-19) pandemic infection on transplant recipients. Given that early reports from heavily affected areas demonstrated a very high mortality rate amongst kidney transplant recipients, ranging between 30% and 40%, we sought to evaluate outcomes at a center with a high burden of cases but not experiencing acute crisis due to COVID-19.

PROCEDURES

In this single center retrospective observational study, medical records of all kidney transplant recipients at the UCLA Medical Center were reviewed for a diagnosis of COVID-19 by polymerase chain reaction, followed by chart review to determine kidney transplant characteristics and clinical course.

MAIN FINDINGS

A total of 41 kidney transplant recipients were identified with COVID-19 positive polymerase chain reaction. Recipients had been transplanted for a median of 47 months before diagnosis. The large proportion of infected individuals were minorities (Hispanic 65.9%, black 14.6%), on prednisone, tacrolimus, and mycophenolate mofetil (95.1%, 87.8%, and 87.8%, respectively), and had excellent allograft function (median 1.25 mg/dL). The most common presenting symptoms were fever, dyspnea, or cough. Most patients were hospitalized (63.4%); mortality was 9.8% and occurred only in patients in the intensive care unit. The most common treatment was reduction or removal of antimetabolite (77.8%). Approximately 26.9% presented with AKI.

CONCLUSIONS

COVID-19 infection in kidney transplant recipients results in a higher rate of hospitalization and mortality than in the general population. In an area with a high number of infections, the mortality rate was lower compared with earlier reports from areas experiencing early surge and strain on the medical system. Minorities were disproportionately affected. Future studies are needed to determine optimal approach to treatment and management of immunosuppression in kidney transplant recipients with COVID-19 infection.

Time to second kidney transplantation in young adults after failed pediatric kidney transplant

BACKGROUND

Under the current kidney allocation system, pediatric candidates listed prior to age 18 receive priority for high-quality deceased donor organs. This has resulted in a decline in living donor transplantation in pediatrics, despite superior outcomes of living donor transplantation. Due to a young age at transplantation, most pediatric kidney transplant recipients require re-transplantation. The effects of a previously failed deceased donor vs a previously failed living donor on re-transplant candidates are unknown.

METHODS

Using the United Network for Organ Sharing database, we examined 2772 re-transplant recipients aged 18-30 years at time of relisting for second KT from 2000 to 2018 with history of prior pediatric KT (age ≤ 18 years).

RESULTS

PFLDKT recipients compared to those with PFDDKT had shorter median waiting times and dialysis time regardless of their second donor type (14.0 vs 20.3 months, and 19.1 vs 34.5 months, respectively). PFLDKT recipients had higher re-transplant rates (adjusted HR 1.17, 95% CI 1.09-1.27, and adjusted HR 1.05, 95% CI 0.95-1.15 when calculating from time of relisting and time of returning to dialysis, respectively). PFDDKT recipients were more likely to have higher median PRA levels (90% vs 73%).

CONCLUSIONS

Re-transplant candidates who received a previous deceased donor as a child had a higher level of sensitization, longer waiting time, and dialysis exposure compared to those with PFLDKT. Among primary pediatric kidney transplant candidates, consideration should be considered for living donor transplantation, despite the priority for deceased donor organs, to avoid increased sensitization and longer waiting times for with re-transplantation.

Effect of Concentration/Dose Ratio in De Novo Kidney Transplant Recipients Receiving LCP-Tacrolimus or Immediate-Release Tacrolimus: Post Hoc Analysis of a Phase 3 Clinical Trial

Background

A previous phase 3 clinical trial in de novo adult kidney transplant recipients (NCT01187953) compared the efficacy and safety of once-daily LCP-tacrolimus (LCPT) and twice-daily immediate-release tacrolimus (IR-Tac). However, whether the rate of tacrolimus metabolism affects outcomes between LCPT and IR-Tac was not examined.

Material/Methods

Patients were initiated on 0.17 mg/kg/day LCPT or 0.1 mg/kg/day IR-Tac, with doses adjusted over time to maintain target therapeutic trough concentrations. This post hoc analysis examined dosing trends, relative efficacy, and safety of LCPT (n=247) and IR-Tac (n=249) in slow, intermediate, and rapid metabolizers as defined by concentration/dose ratios at day 30.

Results

For all metabolizer subgroups, minimum target tacrolimus trough concentrations were obtained more rapidly with LCPT than with IR-Tac. Slow metabolizers were more likely to exceed target trough concentrations with LCPT, while rapid metabolizers were more likely to fall below target trough concentrations with IR-Tac. Regardless of metabolizer status, significant differences were not detected between LCPT and IR-Tac for treatment failure, death, graft failure, biopsy-proven acute rejection, estimated glomerular filtration rate, or other clinical outcomes.

Conclusions

Although within metabolizer subgroups, attainment of target trough concentrations in the first week differed between LCPT and IR-Tac, these results suggest that, regardless of metabolizer phenotype, clinical outcomes do not differ between these formulations when dose adjustments are made.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT01187953

Factors predicting kidney delayed graft function among recipients of simultaneous liver-kidney transplantation: A single-center experience

BACKGROUND

Kidney delayed graft function (kDGF) remains a challenging problem following simultaneous liver and kidney transplantation (SLKT) with a reported incidence up to 40%. Given the scarcity of renal allografts, it is crucial to minimize the development of kDGF among SLKT recipients to improve patient and graft outcomes. We sought to assess the role of preoperative recipient and donor/graft factors on developing kDGF among recipients of SLKT.

METHODS

A retrospective review of 194 patients who received SLKT in the period from January 2004 to March 2017 in a single center was performed to assess the effect of preoperative factors on the development of kDGF.

RESULTS

Kidney delayed graft function was observed in 95 patients (49%). Multivariate analysis revealed that donor history of hypertension, cold static preservation of kidney grafts [versus using hypothermic pulsatile machine perfusion (HPMP)], donor final creatinine, physiologic MELD, and duration of delay of kidney transplantation after liver transplantation were significant independent predictors for kDGF. kDGF is associated with worse graft function and patient and graft survival.

CONCLUSIONS

Kidney delayed graft function has detrimental effects on graft function and graft survival. Understanding the risks and combining careful perioperative patient management, proper recipient selection and donor matching, and graft preservation using HPMP would decrease kDGF among SLKT recipients.

Current Status of Simultaneous Liver-Kidney Transplantation in the United States

On August 10, 2017, a formal policy was enacted in the United States that defined listing criteria for simultaneous liver-kidney transplantation and priority for patients who received a liver transplantation (LT) and subsequently developed significant kidney disease after LT. This article reviews and summarizes the rationale for such policies, the policies themselves, and the potential impact on LT candidates.

Differences in Gene Expression in Older Compared With Younger Kidney Transplant Recipients

BACKGROUND

For the growing numbers of older transplant patients, increased incidence of infection and death compared with younger patients may limit the many benefits provided by transplantation. However, little is known about age-associated immune dysfunction in the older transplant recipient.

METHODS

A cohort of 60 kidney transplant recipients, 23 older (≥ 60y) and 37 younger (30-59y), matched on antithymocyte induction and donor type (living vs deceased) was evaluated. Gene expression in peripheral blood mononuclear cells 3 months after kidney transplantation was analyzed to compare differences between older and younger patients.

RESULTS

Proinflammatory genes were upregulated in older kidney transplant patients, including cytokines IL1-β and IL-6. Downregulated genes were associated with B-cell and T-cell function, including CCR7 and CD27. Analysis of predicted transcription factor binding suggested an increase in proinflammatory transcription factor CCAAT/enhancer binding protein β-binding sites in older patients, whereas interferon regulatory factor 2 transcription factor binding sites were less prevalent.

CONCLUSIONS

Older kidney transplant recipients exhibited multiple differences in gene expression compared with younger patients, with upregulation of proinflammatory genes and downregulation of adaptive immune response genes. These findings may explain the mechanism of increased vulnerability to infection and malignancy observed in older transplant patients.

Predictors of Early and Late Mortality in Older Kidney Transplant Recipients

BACKGROUND

Older kidney patients with chronic kidney disease benefit significantly from kidney transplantation. However, these older transplant recipients have greater mortality after transplantation than younger transplant recipients. Understanding the impact of comorbidities on post-transplant mortality can improve risk stratification and patient selection.

METHODS

A single-center analysis of 3105 kidney transplant recipients was performed over a 12-year period. Comorbidities associated with death were evaluated in older and younger transplant recipients.

RESULTS

The 2 most important factors associated with increased mortality in the first 100 days after transplant were recipient age ≥60 and receipt of deceased donor organs (adjusted odds ratios, 3.29 and 5.80, respectively), with no statistically significant impact of recipient comorbidities. In the later post-transplant period (after the first 100 days), recipient age ≥60 and receipt of deceased donor organs (adjusted hazard ratios [HR] of 2.14 and 2.29, respectively) remained predictors of mortality. We also found that donor age ≥60 and the recipient having cardiovascular disease and diabetes were independent predictors of increased mortality. There was a statistically significant interaction between diabetes and heart disease and recipient age ≥60, with a lesser impact on late mortality in older patients compared to younger patients.

CONCLUSIONS

This analysis suggests that comorbidities have a larger impact later after transplantation, with less effect on older recipients. These observations suggest that certain comorbid conditions should be evaluated differently in older patients compared to younger ones.

629. Blood Transcriptome Variations Predict Infection and Rejection in the Older Kidney Transplant Recipient

Background

Compared with younger patients on similar immunosuppression regimens, older solid-organ transplant recipients experience increased rates of infection and death, but decreased rates of rejection. Our previous findings demonstrated increased T-cell immunosenescence and pro-inflammatory monocytes in older patients. This study sought to define the implications of transcriptome alterations for clinical outcomes. The objective of this abstract is to evaluate older vs. younger solid-organ transplant recipients for differential patterns of gene expression associated with infection and rejection.

Methods

Peripheral blood mononuclear cells were isolated from 23 older (≥age 60) and 37 matched younger (ages 30–59) kidney transplant recipients at 3 months after transplantation. RNA extraction was performed on banked PBMCs. Isolated RNA was converted to fluorescent cRNA and hybridized to Illumina Human HT-12 v4 BeadArrays. Gene expression values were quantile-normalized and log2-transformed for mixed effect linear model analyses to identify differential expression as a function of age, adjusted for induction type, donor type, and sex. Statistical analysis was performed using R software.

Results

Genes differentially expressed in older patients revealed an over-representation of pro-inflammatory genes and a down regulation of genes associated with the CD8 immune response. Patients who went on to develop infection demonstrated an increase in IRF transcription factor activation and plasmacytoid dendritic cell activity. Patients who developed rejection demonstrated an increase in myeloid lineage immune cell activity.

Conclusion

Differential patterns of gene expression were observed in patients who developed infection in the first year after kidney transplantation. These findings were distinct from the gene expression changes associated with development of rejection. These findings may explain the mechanism behind vulnerability to infection in older transplant patients. In addition, monitoring of changes in gene expression may provide an avenue for patient monitoring after transplantation as well as individualization of immune suppression after solid-organ transplantation.

Disclosures

All authors: No reported disclosures.

Combined Dual-Kidney Liver Transplantation in the United States: A Review of United Network for Organ Sharing/Organ Procurement and Transplantation Network Data Between 2002 and 2012

In kidney-alone recipients, dual-kidney transplantation using "higher-risk" donor organs has shown outcomes comparable to those of single-kidney transplantation using extended criteria donor (ECD) organs. To investigate the feasibility of a similar approach with combined kidney-liver transplantation, we identified 22 dual-kidney liver transplantations (DKLTs) and 3044 single-kidney liver transplantations (SKLTs) performed in the United States between 2002 and 2012 using United Network for Organ Sharing/Organ Procurement and Transplantation Network registry data. We compared donor/recipient characteristics as well as graft/recipient survival between DKLT recipients and SKLT recipients of "higher-risk" kidneys (ECD and high kidney donor profile index [KDPI; >85%] donors). Despite having overall similar donor and recipient characteristics compared with both "higher-risk" donor groups, recipient survival in the DKLT group at 36 months was markedly inferior at 40.9% (compared with 67.5% for ECD SKLT recipients and 64.5% for high-KDPI SKLT recipients); nondeath-censored graft survival did not differ. Death was the most common cause of graft loss in all groups. Contrary to dual-kidney transplantation data in kidney-alone recipients, DKLT recipients in our study had inferior survival when compared with SKLT recipients of "higher-risk" donor kidneys. These findings would suggest that dual kidney-liver transplantation has an uncertain role as a strategy to expand the existing kidney donor pool in combined transplantation.

Donor-derived Cell-free DNA Identifies Antibody-mediated Rejection in Donor Specific Antibody Positive Kidney Transplant Recipients

BACKGROUND

Elevated levels of donor-derived cell-free DNA (dd-cfDNA) in the plasma of renal allograft recipients indicates organ injury and an increased probability of active rejection. Donor-specific antibodies (DSA) to HLA antigens are associated with risk of antibody-mediated rejection (ABMR). This study assessed the combined use of dd-cfDNA and DSA testing to diagnose active ABMR.

METHODS

Donor-derived cell-free DNA was assayed in 90 blood samples with paired DSA and clinically indicated biopsies from 87 kidney transplant patients. Sixteen cases met criteria for active ABMR. Performance characteristics of dd-cfDNA for diagnosis of active ABMR were determined for samples with prior or current positive DSA (DSA+, n = 33).

RESULTS

The median level of dd-cfDNA (2.9%) in DSA+ patients with active ABMR was significantly higher than the median level (0.34%) in DSA+ patients without ABMR (P < 0.001). The median level of dd-cfDNA in DSA- patients was 0.29%. The positive predictive value of dd-cfDNA (at 1%) to detect active ABMR in DSA+ patients was 81%, whereas the negative predictive value was 83%. The positive predictive value for DSA+ alone was 48%.

CONCLUSIONS

The combined use of dd-cfDNA and DSA testing may improve the noninvasive diagnosis of active ABMR in kidney transplant patients. Patients with dd-cfDNA+/ DSA+ results have a high probability of active ABMR.

Three patients with injection of intravitreal vascular endothelial growth factor inhibitors and subsequent exacerbation of chronic proteinuria and hypertension

Vascular endothelial growth factor (VEGF) receptor inhibition is a commonly used tool to prevent vascular proliferation in tumors and retinal diseases. The antiangiogenic effects of these drugs have made them potent adjunct therapies when given systemically for malignancies. They are also useful tools to ameliorate diminishing eyesight in retinopathy. Hypertension and proteinuria have been observed in systemic VEGF inhibitor therapy, with rarer presentations involving nephrotic-range proteinuria due to glomerulopathies. Pharmacokinetic studies have shown detectable blood levels of anti-VEGF inhibitors up to 30 days postintravitreal injection. Animal studies have also demonstrated binding of VEGF inhibitors in simian glomeruli 1 week after a single intravitreal injection. We report three patients who received intravitreal bevacizumab and/or aflibercept with worsening hypertension, proteinuria and renal injury. Data regarding emerging evidence of VEGF inhibitor nephrotoxicity after intravitreal injections are also presented. The clinical data and the existing literature are reviewed to support the hypothesis that intravitreal anti-VEGF agents may be unrecognized nephrotoxins. These agents are given to vulnerable patients with diabetes, hypertension and preexisting nephropathy and proteinuria. This case series is reported to spur further study of the systemic effects of intravitreal VEGF inhibitors.

Screening Coccidioides serology in kidney transplant recipients: A 10-year cross-sectional analysis

BACKGROUND

Kidney transplant recipients (KTRs) are at risk for reactivation and complicated infection due to Coccidioides. Pre-transplant serological screening should provide benefit for patients from endemic areas. We evaluated Coccidioides seroprevalence by area of residence in KTRs at a major transplant program in Los Angeles.

METHODS

We performed cross-sectional analyses of adult KTRs who underwent transplantation at UCLA between 2007-2016. Patients with Coccidioides serology by enzyme immunoassay (EIA) before or within 14 days from transplantation were included. Patients were classified as living in highly, established, suspected, or not endemic areas by their residential zip code.

RESULTS

Overall prevalence of Coccidioides IgG and IgM were 1.4% and 2.8%, respectively. Of patients with positive serology, 31.4% had isolated IgG and 66.3% isolated IgM. Patients from established and highly endemic areas had IgG seropositivity of 3.7% versus 1.3% for patients living in suspected endemic areas(P < .01). Rates of IgM seropositivity were 3.7% compared to 2.8% respectively (P = .28). No patients from non-endemic areas had positive screening serology.

CONCLUSIONS

Pre-transplant serological screening for Coccidioides is recommended in kidney transplant candidates from endemic areas. We observed high seroprevalence among patients from highly and established endemic areas, for whom universal prophylaxis is recommended. For residents from less well-established areas of endemicity, serological screening showed benefit in identifying patients at risk. In patients with isolated EIA IgM, performing repeat and confirmatory tests is recommended. Patients from non-endemic areas had low risk of infection, however, a thorough social history is necessary to evaluate risk.