CMV-Specific T Cell Monitoring Offers Superior Risk Stratification of CMV-Seronegative Kidney Transplant Recipients of a CMV-Seropositive Donor

Cellular immunity against cytomegalovirus and risk of infection after kidney transplantation

Introduction

Cytomegalovirus (CMV) infection remains a challenge following kidney transplantation (KTx). Currently, CMV-IgG serostatus at transplantation is used to individualize CMV preventive strategies. We assessed the clinical utility of CMV-IGRA for predicting CMV infection following KTx.

Methods

We performed a nationwide prospective cohort study from August 2016 until December 2022. Data from all adult KTx recipients in Norway, n=1,546 (R+; n=1,157, D+/R-; n=260, D-/R-; 129), were included with a total of 3,556 CMV-IGRA analyses (1,375 at KTx, 1,188 at eight weeks, 993 one-year after KTx) and 35,782 CMV DNAemia analyses.

Results

In R+ recipients CMV-IGRA status, measured at any of the time-points, could not identify any differential risk of later CMV infection. D+/R- recipients remaining CMV-IGRA negative 1-year after transplantation (regardless of positive CMV DNAemia and/or CMV IgG status at that time) had increased risk of developing later CMV infection compared to D+/R- recipients who had become CMV-IGRA positive (14% vs. 2%, p=0.01).

Conclusion

Knowledge of pre-transplant CMV-IGRA status did not provide additional information to CMV-IgG serostatus that could improve current post-transplant CMV treatment algorithms. However, D+/R- recipients with a persisting negative CMV-IGRA one-year after transplantation remained at increased risk of experiencing later CMV infection. Therefore we advocate post-transplant CMV-IGRA monitoring in these patients.

Prevention of Cytomegalovirus Infection in Solid Organ Transplant Recipients: Guidelines by the Korean Society of Infectious Diseases and the Korean Society for Transplantation

Cytomegalovirus (CMV) is the most important opportunistic viral pathogen in solid organ transplant (SOT) recipients. The Korean guideline for the prevention of CMV infection in SOT recipients was developed jointly by the Korean Society for Infectious Diseases and the Korean Society of Transplantation. CMV serostatus of both donors and recipients should be screened before transplantation to best assess the risk of CMV infection after SOT. Seronegative recipients receiving organs from seropositive donors face the highest risk, followed by seropositive recipients. Either antiviral prophylaxis or preemptive therapy can be used to prevent CMV infection. While both strategies have been demonstrated to prevent CMV infection post-transplant, each has its own advantages and disadvantages. CMV serostatus, transplant organ, other risk factors, and practical issues should be considered for the selection of preventive measures. There is no universal viral load threshold to guide treatment in preemptive therapy. Each institution should define and validate its own threshold. Valganciclovir is the favored agent for both prophylaxis and preemptive therapy. The evaluation of CMV-specific cell-mediated immunity and the monitoring of viral load kinetics are gaining interest, but there was insufficient evidence to issue recommendations. Specific considerations on pediatric transplant recipients are included.

Cytomegalovirus Cell-mediated Immunity Assays in Pediatric Transplantation

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality in pediatric transplantation. However, currently utilized CMV prevention paradigms have limitations, leading to research aimed at novel strategies for mitigation of CMV infection. Cell-mediated immunity (CMI) is crucial in controlling CMV infection and the use of CMV-specific CMI assays to guide prevention and treatment of CMV infection in both solid organ transplant and hematopoietic cell transplant recipients shows great promise. In this article, we review the immune response to CMV infection to highlight the rationale for CMI assays, describe available commercial assays and strategies for their use, and summarize relevant literature regarding the use of CMI assays in transplant recipients.

Using a commercially available assay that measures cytomegalovirus (CMV)-specific T-cell immunity to predict protection against CMV: A prospective, blinded clinical study

The Viracor CMV-T-cell immunity Panel (TCIP) measures %CMV-specific CD4+ and CD8+ T-cells. In this blinded clinical study, we evaluated the performance of the TCIP in predicting CMV events. Prospectively enrolled donor or recipient CMV-seropositive kidney transplant recipients (KTR) were evaluated with monthly TCIP testing until either discontinuation of valganciclovir prophylaxis or CMV DNAemia prompting treatment initiation. Also, prospectively enrolled KTR with low-level untreated DNAemia or after completion of treatment were evaluated for progression or relapse of CMV infection. Among 46 KTR, those with CMV events had significantly lower %CMV-specific CD8+ T-cells (p = 0.024), and the CMV protection ROC AUC was significant (AUC 0.78, p = 0.026). The positive predictive values of CD4+ and CD8+ T-cell positivity >0.2 % for CMV protection were: 96.3 % for CMV DNAemia prompting treatment initiation, 92.6 % for any DNAemia, 100 % for DNAemia >1000 IU/mL. The TCIP could be a useful adjunct tool in individualized management of CMV infection.

Management of Cytomegalovirus Infections in the Era of the Novel Antiviral Players, Letermovir and Maribavir

Cytomegalovirus (CMV) infections may increase morbidity and mortality in immunocompromised patients. Until recently, standard antiviral drugs against CMV were limited to viral DNA polymerase inhibitors (val)ganciclovir, foscarnet and cidofovir with a risk for cross-resistance. These drugs may also cause serious side effects. This narrative review provides an update on new antiviral agents that were approved for the prevention and treatment of CMV infections in transplant recipients. Letermovir was approved in 2017 for CMV prophylaxis in CMV-seropositive adults who received an allogeneic hematopoietic stem cell transplant. Maribavir followed four years later, with an indication in the treatment of adult and pediatric transplant patients with refractory/resistant CMV disease. The target of letermovir is the CMV terminase complex (constituted of pUL56, pUL89 and pUL51 subunits). Letermovir prevents the cleavage of viral DNA and its packaging into capsids. Maribavir is a pUL97 kinase inhibitor, which interferes with the assembly of capsids and the egress of virions from the nucleus. Both drugs have activity against most CMV strains resistant to standard drugs and exhibit favorable safety profiles. However, high-level resistance mutations may arise more rapidly in the UL56 gene under letermovir than low-grade resistance mutations. Some mutations emerging in the UL97 gene under maribavir can be cross-resistant with ganciclovir. Thus, letermovir and maribavir now extend the drug arsenal available for the management of CMV infections and their respective niches are currently defined.

Reliability of QuantiFERON®-CMV in predicting CMV recurrence in heart transplant recipients: A single-center retrospective study

BACKGROUND

Recurrence after Cytomegalovirus (CMV) infection in heart transplant recipients is difficult to predict, in spite of its high incidence. Secondary prophylaxis could reduce this burden; however, its duration remains unestablished. We evaluated the QuantiFERON®-CMV test to see if it could predict CMV recurrence and help optimize the duration of secondary prophylaxis.

METHODS

This observational retrospective single center study included all heart transplant recipients who developed CMV infection between 2019 and 2021, with the CD8+ T-cell-mediated CMV immunity QuantiFERON®-CMV test assessed at the time of (val)ganciclovir curative treatment completion. The main outcomes were CMV recurrence and duration of secondary prophylaxis. Secondary outcomes included immunosuppressive regimen, rejection, lymphocyte count, CMV viral load, infection type, and duration as possible confounding factors for recurrence.

RESULTS

Among the 15 patients included, five (33%) experienced recurrence, of whom three (60%) had a positive QuantiFERON®-CMV test. The duration of secondary prophylaxis was similar regardless of QF-CMV positivity. No confounding factor was significantly associated with CMV recurrence; however, it occurred in only 1/7 (14%) of the patients receiving an everolimus-containing immunosuppressive regimen.

CONCLUSION

In the population of heart transplant recipients, most of whom received ATG-based induction, the QuantiFERON®-CMV assay may not accurately predict CMV recurrence and would have not helped refining the duration of secondary prophylaxis in our patients. Other cell-mediated immunity tests and strategies in this specific population, including everolimus-containing regimens, may help predict and manage CMV recurrence.

Cytomegalovirus Cell-Mediated Immunity: Ready for Routine Use?

Utilizing assays that assess specific T-cell-mediated immunity against cytomegalovirus (CMV) holds the potential to enhance personalized strategies aimed at preventing and treating CMV in organ transplantation. This includes improved risk stratification during transplantation compared to relying solely on CMV serostatus, as well as determining the optimal duration of antiviral prophylaxis, deciding on antiviral therapy when asymptomatic replication occurs, and estimating the risk of recurrence. In this review, we initially provide an overlook of the current concepts into the immune control of CMV after transplantation. We then summarize the existent literature on the clinical experience of the use of immune monitoring in organ transplantation, with a particular interest on the outcomes of interventional trials. Current evidence indicates that cell-mediated immune assays are helpful in identifying patients at low risk for replication for whom preventive measures against CMV can be safely withheld. As more data accumulates from these and other clinical scenarios, it is foreseeable that these assays will likely become part of the routine clinical practice in organ transplantation.

Peripheral Blood Absolute Lymphocyte Count as a Predictor of Cytomegalovirus Infection in Kidney Transplant Recipients

BACKGROUND

Cytomegalovirus viremia and infection have been reported to increase the risks for acute graft rejection and mortality in kidney transplant recipients. Previous studies demonstrated that a lower absolute lymphocyte count in peripheral blood is associated with cytomegalovirus infection. The aim of this study was to investigate whether absolute lymphocyte count could predict cytomegalovirus infection in kidney transplant recipients.

METHODS

From January 2010 to October 2021, 48 living kidney transplant recipients in whom both donor and recipient were positive for immunoglobulin G of cytomegalovirus were included in this retrospective study. The primary outcome was defined as cytomegalovirus infection occurring ≥28 days after kidney transplantation. All recipients were followed for 1 year after kidney transplantation. The diagnostic accuracy of absolute lymphocyte count on day 28 post-transplantation for cytomegalovirus infection was analyzed using receiver operating characteristic curves. A Cox proportional hazards model was used to calculate hazard ratios for the incidence of cytomegalovirus infection.

RESULTS

There were 13 patients (27%) with cytomegalovirus infection. The sensitivity and specificity for cytomegalovirus infection were 62% and 71%, respectively; the negative predictive value was 83% when an absolute lymphocyte count of 1100 cells/μL on day 28 post-transplantation was used as the cutoff. The incidence of cytomegalovirus infection was significantly higher when the absolute lymphocyte count was <1100 cells/μL on day 28 post-transplantation (hazard ratio, 3.32; 95% CI, 1.08-10.2).

CONCLUSION

Absolute lymphocyte count is an inexpensive and easy test that can effectively predict cytomegalovirus infection. Further validation is needed to confirm its utility.

Cytomegalovirus Management in Solid Organ Transplant Recipients: A Pre-COVID-19 Survey From the Working Group of the European Society for Organ Transplantation

Infections are leading causes of morbidity/mortality following solid organ transplantation (SOT) and cytomegalovirus (CMV) is among the most frequent pathogens, causing a considerable threat to SOT recipients. A survey was conducted 19 July–31 October 2019 to capture clinical practices about CMV in SOT recipients (e.g., how practices aligned with guidelines, how adequately treatments met patients’ needs, and respondents’ expectations for future developments). Transplant professionals completed a ∼30-minute online questionnaire: 224 responses were included, representing 160 hospitals and 197 SOT programs (41 countries; 167[83%] European programs). Findings revealed a heterogenous approach to CMV diagnosis and management and, sometimes, significant divergence from international guidelines. Valganciclovir prophylaxis (of variable duration) was administered by 201/224 (90%) respondents in D+/R− SOT and by 40% in R+ cases, with pre-emptive strategies generally reserved for R+ cases: DNA thresholds to initiate treatment ranged across 10–10,000 copies/ml. Ganciclovir-resistant CMV strains were still perceived as major challenges, and tailored treatment was one of the most important unmet needs for CMV management. These findings may help to design studies to evaluate safety and efficacy of new strategies to prevent CMV disease in SOT recipients, and target specific educational activities to harmonize CMV management in this challenging population.

Utility of Cytomegalovirus Cell-Mediated Immunity Assays in Solid Organ Transplantation

Cytomegalovirus (CMV) is one of the most important viral complications after solid organ transplantation (SOT). Current preventive and management strategies rely primarily on serologic and viral load testing and remain suboptimal. To address these issues, multiple techniques to measure CMV-specific cell-mediated immunity (CMI) have been developed and evaluated in clinical studies over the past two decades. These assays show significant promise for the personalization of CMV management. For example, CMI assays can be used to help determine the optimal duration of antiviral prophylaxis or whether antiviral therapy is indicated in patients with low levels of CMV reactivation. However, despite numerous studies showing potential utility, these assays are not yet in widespread routine clinical use. Barriers to adoption include variations in test complexity, standardization, and thresholds for positivity and insufficient interventional clinical trials. Here, we provide an updated assessment of commonly available tests and the clinical utility of CMV-specific CMI testing in SOT recipients.

Laboratory diagnostic testing for cytomegalovirus infection in solid organ transplant patients

Human cytomegalovirus (CMV) infection, which is one of the most common complications in transplant recipients, increases the risk of graft loss and rejection. Laboratory strategies for diagnosing CMV infection rely on the measurement of viral DNAemia and CMV-specific cell-mediated immunity (CMV-CMI). The CMV quantitative nucleic acid amplification test (QNAT) enabled the spread of preemptive therapy and prompted recommendations for surveillance, diagnosis, and monitoring. Despite the implementation of the World Health Organization international standard for calibration, variability of QNAT persists due to technical issues. CMV immunoglobulin G serology is the standard method for CMV immune screening of transplant candidates and donors. Assays for CMV-CMI play an important role in helping to predict the risk and to develop an individualized CMV management plan. Genotypic testing for resistance is needed when drug-resistant CMV infection is suspected. Here, we review the state of the art of laboratory tests for CMV infection in solid organ transplantation.

Cytomegalovirus transmission in mismatched solid organ transplant recipients: Are factors other than anti-viral prophylaxis at play?

Although antiviral prophylaxis has reduced cytomegalovirus (CMV) DNAemia and disease in seronegative solid organ transplant (SOT) recipients (R-) receiving seropositive donor organs (D+), its impact on CMV transmission is uncertain. Transmission, defined as CMV antigenemia/CMV DNAemia and/or seroconversion by year 2, and associated demographic risk factors were studied retrospectively in 428 D+/R- and 429 D-/R- patients receiving a SOT at our center. The cumulative transmission incidence was higher for lung (90.5%) and liver recipients (85.1%) than heart (72.7%), kidney (63.9%), and pancreas (56.2%) recipients (p < .001) and was significantly lower in living (50.1%) versus deceased donor (77.4%, p < .001) kidney recipients despite identical antiviral prophylaxis. In multivariate analysis, only allograft type predicted transmission risk (HR [CI] lung 1.609 [1.159, 2.234] and liver 1.644 [1.209, 2.234] vs kidney). For 53 D+ donating to >1 R- with adequate follow-up, 43 transmitted to all, three transmitted to none, and seven transmitted inconsistently with lungs and livers always transmitting but donor-matched heart, kidney or kidney-pancreas allografts sometimes not. Kidney pairs transmitted concordantly. CMV transmission risk is allograft-specific and unchanged despite antiviral prophylaxis. Tracking transmission and defining donor factors associated with transmission escape may provide novel opportunities for more targeted CMV prevention and improve outcome analysis in antiviral and vaccine trials.

Novel ways to monitor immunosuppression in pediatric kidney transplant recipients-underlying concepts and emerging data

After pediatric kidney transplantation, immunosuppressive therapy is given to avoid acute and chronic rejections. However, the immunosuppression causes an increased risk of severe viral complications and bacterial infections and is associated with serious side effects. It is therefore crucial to achieve the optimal individual balance between over- and under-immunosuppression and thereby avoid unnecessary exposure to immunosuppressive drugs. In routine use, steering of immunosuppressants is performed primarily by monitoring of trough levels that mirror pharmacokinetics (although not, however, pharmacodynamics). Other diagnostic and prognostic markers to assess the individual intensity of immunosuppression are missing. Potential methods to determine immune function and grade of immunosuppression, such as analysis of the torque teno virus (TTV) load, QuantiFERON Monitor®, and ImmuKnow® as well as virus-specific T cells (Tvis), are currently being evaluated. In some studies TTV load, QuantiFERON Monitor® and ImmuKnow® were associated with the risk for post-transplant rejections and infections, but randomized controlled trials after pediatric kidney transplantation are not available. Post-transplant monitoring of Tvis levels seem to be promising because Tvis control virus replication and have been shown to correlate with virus-specific as well as general cellular immune defense, which represents the individual’s susceptibility to infections. Additional Tvis-monitoring provides an innovative opportunity to personalize the antiviral management and the dosing of the immunosuppressive therapy after pediatric kidney transplantation to avoid unnecessary therapeutic interventions and identify over-immunosuppression.

Use of Letermovir-Valganciclovir combination as a step-down treatment after Foscarnet for Ganciclovir-resistant CMV infection in kidney transplant recipients

Background

Letermovir (LTV) might be an alternative treatment to nephrotoxic foscarnet (FOS) in Ganciclovir (GCV) resistant cytomegalovirus (CMV) infection. However, its efficacy in controlling active CMV viremia is unclear, as it is only approved for CMV prophylaxis in hematopoietic stem‐cell transplantation.

Methods

This case series describes 14 kidney transplant recipients (KTR) with moderate‐level GCV resistant CMV infection, treated by different step‐down strategies after initial FOS therapy: (1) Observation without antiviral follow‐up or switch to valganciclovir (VGCV) (pre‐LTV era), and (2) Switch to LTV±VGCV (LTV era).

Results

One patient died under FOS. Thirteen patients were followed under step‐down regimens. All but two patients had ongoing CMV viremia when stopping FOS. In pre‐LTV era, 5/9 (56%) experienced a CMV breakthrough > 10 000 IU/ml calling for another course of FOS, as compared to 1/4 (25%) in the LTV era. Addition of VGCV to LTV at low‐level viral breakthrough, addressing a possible developing resistance against LTV, prevented viral surge in two patients. In the pre‐LTV era, CMV‐related death or graft loss occurred in three of nine (33%), compared to no death or graft loss in the LTV era.

Conclusion

A step‐down strategy combining LTV+VGCV, might allow to safely stop FOS at ongoing low‐level viremia.

Utility of CMV-Specific Immune Monitoring for the Management of CMV in Solid Organ Transplant Recipients: A Clinical Update

Cytomegalovirus (CMV) is one of the most important opportunistic infections in solid organ transplant (SOT) recipients. However, current techniques used to predict risk for CMV infection fall short. CMV-specific cell mediated immunity (CMI) plays an important role in protecting against CMV infection. There is evidence that assays measuring CMV-CMI might better identify SOT recipients at risk of complications from CMV compared to anti-CMV IgG, which is our current standard of care. Here, we review recently published studies that utilize CMV-CMI, at various points before and after transplantation, to help predict risk and guide the management of CMV infection following organ transplantation. The evidence supports the use of these novel assays to help identify SOT recipients at increased risk and highlights the need for larger prospective trials evaluating these modalities in this high-risk population.

Cellular Immunity to Predict the Risk of Cytomegalovirus Infection in Kidney Transplantation: A Prospective, Interventional, Multicenter Clinical Trial

BACKGROUND

Improving cytomegalovirus (CMV) immune-risk stratification in kidney transplantation is highly needed to establish guided preventive strategies.

METHODS

This prospective, interventional, multicenter clinical trial assessed the value of monitoring pretransplant CMV-specific cell-mediated immunity (CMI) using an interferon-γ release assay to predict CMV infection in kidney transplantation. One hundred sixty donor/recipient CMV-seropositive (D+/R+) patients, stratified by their baseline CMV (immediate-early protein 1)-specific CMI risk, were randomized to receive either preemptive or 3-month antiviral prophylaxis. Also, 15-day posttransplant CMI risk stratification and CMI specific to the 65 kDa phosphoprotein (pp65) CMV antigen were investigated. Immunosuppression consisted of basiliximab, tacrolimus, mycophenolate mofetil, and corticosteroids in 80% of patients, whereas 20% received thymoglobulin induction therapy.

RESULTS

Patients at high risk for CMV based on pretransplant CMI developed significantly higher CMV infection rates than those deemed to be at low risk with both preemptive (73.3% vs 44.4%; odds ratio [OR], 3.44 [95% confidence interval {CI}, 1.30-9.08]) and prophylaxis (33.3% vs 4.1%; OR, 11.75 [95% CI, 2.31-59.71]) approaches. The predictive capacity for CMV-specific CMI was only found in basiliximab-treated patients for both preemptive and prophylaxis therapy. Fifteen-day CMI risk stratification better predicted CMV infection (81.3% vs 9.1%; OR, 43.33 [95% CI, 7.89-237.96]).

CONCLUSIONS

Pretransplant CMV-specific CMI identifies D+/R+ kidney recipients at high risk of developing CMV infection if not receiving T-cell-depleting antibodies. Monitoring CMV-specific CMI soon after transplantation further defines the CMV infection prediction risk. Monitoring CMV-specific CMI may guide decision making regarding the type of CMV preventive strategy in kidney transplantation.

CLINICAL TRIALS REGISTRATION

NCT02550639.

CRISPR-Cas9-Edited Tacrolimus-Resistant Antiviral T Cells for Advanced Adoptive Immunotherapy in Transplant Recipients

Viral infections, such as with cytomegalovirus (CMV), remain a major risk factor for mortality and morbidity of transplant recipients because of their requirement for lifelong immunosuppression (IS). Antiviral drugs often cause toxicity and sometimes fail to control disease. Thus, regeneration of the antiviral immune response by adoptive antiviral T cell therapy is an attractive alternative. Our recent data, however, show only short-term efficacy in some solid organ recipients, possibly because of malfunction in transferred T cells caused by ongoing IS. We developed a vector-free clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9-based good manufacturing practice (GMP)-compliant protocol that efficiently targets and knocks out the gene for the adaptor protein FK506-binding protein 12 (FKBP12), required for the immunosuppressive function of tacrolimus. This was achieved by transient delivery of ribonucleoprotein complexes into CMV-specific T cells by electroporation. We confirmed the tacrolimus resistance of our gene-edited T cell products in vitro and demonstrated performance comparable with non-tacrolimus-treated unmodified T cells. The alternative calcineurin inhibitor cyclosporine A can be administered as a safety switch to shut down tacrolimus-resistant T cell activity in case of adverse effects. Furthermore, we performed safety assessments as a prerequisite for translation to first-in-human applications.

CMV high-risk status and posttransplant outcomes in kidney transplant recipients treated with belatacept

INTRODUCTION

Cytomegalovirus (CMV) remains associated with poor outcomes after kidney transplantation (kTx). The impact of belatacept on CMV infection remains understudied. In this study, we assessed the impact of belatacept on patient and graft survivals.

METHODS

CMV seronegative kTx recipients were included. Patient and graft survival were studied using Kaplan-Meier method, log-rank test. Cox models were used to compare outcomes by CMV risk and immunosuppressive regimen. Incidence and persistence of CMV viremia under belatacept vs tacrolimus were compared.

RESULTS

Among 308 CMV seronegative recipients, 168 CMV high-risk and 203 belatacept-treated patients were included. High-risk CMV status was associated with lower patient survival and graft survival. Among the CMV high-risk group, patients treated with belatacept presented a higher incidence of CMV viremia, a higher rate of first-line treatment failure and a longer time to virus clearance. They had a nonsignificant trend toward a lower graft survival.

CONCLUSION

Belatacept-based maintenance immunosuppression is associated with an increased risk of CMV primary-infection and a prolonged course of viral replication in CMV high-risk patients. Further studies are needed to confirm the nonsignificant trend towards a lower graft survival in CMV high-risk patients treated with belatacept and whether it is explained by the higher risk of CMV reactivation and infection.

Virus-specific T cells in pediatric renal transplantation

After pediatric kidney transplantation, immunosuppressive therapy causes an increased risk of severe viral complications, especially from cytomegalovirus (CMV), BK polyomavirus (BKPyV) or Epstein-Barr virus (EBV), and less frequent from adenovirus (ADV). However, suitable predictive markers for the individual outcome of viral infections are missing and the therapeutic management remains a challenge to the success of pediatric kidney transplantation. Virus-specific T cells are known for controlling viral replication and there is growing evidence that virus-specific T cells may serve as a prognostic marker to identify patients at risk for viral complications. This review provides an overview of the usability of virus-specific T cells for improving diagnostic and therapeutic management of viral infections with reference to the necessity of antiviral prophylaxis, timing of pre-emptive therapy, and dosing of immunosuppressive medication after pediatric kidney transplantation. Several studies demonstrated that high levels of virus-specific T cells are associated with decrease of virus load and favorable outcome, whereas lack of virus-specific T cells coincided with virus-induced complications. Accordingly, the additional monitoring of virus-specific T cells aims to personalize the management of antiviral therapy, identify overimmunosuppression, and avoid unnecessary therapeutic interventions. Prospective randomized trials in pediatric kidney recipients comparing standard antiviral and immunosuppressive regimens with T cell-guided therapeutic interventions are needed, before monitoring of virus-specific T cells is implemented in the routine care of pediatric kidney graft recipients.

Recent Approaches and Strategies in the Generation of Anti-human Cytomegalovirus Vaccines

Human cytomegalovirus is the largest human herpesvirus and shares many core features of other herpesviruses such as tightly regulated gene expression during genome replication and latency as well as the establishment of lifelong persistence following infection. In contrast to stereotypic clinical syndromes associated with alpha-herpesvirus infections, almost all primary HCMV infections are asymptomatic and acquired early in life in most populations in the world. Although asymptomatic in most individuals, HCMV is a major cause of disease in hosts with deficits in adaptive and innate immunity such as infants who are infected in utero and allograft recipients following transplantation. Congenital HCMV is a commonly acquired infection in the developing fetus that can result in a number of neurodevelopmental abnormalities. Similarly, HCMV is a major cause of disease in allograft recipients in the immediate and late posttransplant period and is thought to be a major contributor to chronic allograft rejection. Even though HCMV induces robust innate and adaptive immune responses, it also encodes a vast array of immune evasion functions that are thought aid in its persistence. Immune correlates of protective immunity that prevent or modify intrauterine HCMV infection remain incompletely defined but are thought to consist primarily of adaptive responses in the pregnant mother, thus making congenital HCMV a potentially vaccine modifiable disease. Similarly, HCMV infection in allograft recipients is often more severe in recipients without preexisting adaptive immunity to HCMV. Thus, there has been a considerable effort to modify HCMV specific immunity in transplant recipient either through active immunization or passive transfer of adaptive effector functions. Although efforts to develop an efficacious vaccine and/or passive immunotherapy to limit HCMV disease have been underway for nearly six decades, most have met with limited success at best. In contrast to previous efforts, current HCMV vaccine development has relied on observations of unique properties of HCMV in hopes of reproducing immune responses that at a minimum will be similar to that following natural infection. However, more recent findings have suggested that immunity following naturally acquired HCMV infection may have limited protective activity and almost certainly, is not sterilizing. Such observations suggest that either the induction of natural immunity must be specifically tailored to generate protective activity or alternatively, that providing targeted passive immunity to susceptible populations could be prove to be more efficacious.

Progress and Challenges in the Prevention, Diagnosis, and Management of Cytomegalovirus Infection in Transplantation

Hosts with compromised or naive immune systems, such as individuals living with HIV/AIDS, transplant recipients, and fetuses, are at the highest risk for complications from cytomegalovirus (CMV) infection. Despite substantial progress in prevention, diagnostics, and treatment, CMV continues to negatively impact both solid-organ transplant (SOT) and hematologic cell transplant (HCT) recipients. In this article, we summarize important developments in the field over the past 10 years and highlight new approaches and remaining challenges to the optimal control of CMV infection and disease in transplant settings.

Transfusion-transmitted and community-acquired cytomegalovirus infection in seronegative solid organ transplant recipients receiving seronegative donor organs

Solid organ transplant (SOT) recipients who are cytomegalovirus (CMV) seronegative (R-) and receive seronegative donor (D-) organs have a small but currently unquantified risk of both transfusion-transmitted CMV (TT-CMV) and community-acquired CMV (CA-CMV). We retrospectively studied the incidence and clinical symptoms of TT-CMV (infection <1 year posttransplant) and CA-CMV (infection >1 year posttransplant) in a cohort of D-/R- adult and pediatric SOT recipients receiving leukoreduced blood products not screened for CMV seronegativity transplanted at our center between 2000 and 2011. CMV infection was defined as IgG seroconversion or detectable CMV antigenemia/DNAemia. Among 536 consecutive D-/R- recipients, 398 (81.8%) had adequate follow-up, and 231 (58%) received cellular blood products (total: 1626 red blood cell units, 470 platelet units) 30 days pretransplant to 90 days posttransplant. We observed no confirmed TT-CMV cases, but 14 CA-CMV cases (64% symptomatic) were seen. The estimated incidence rate of CA-CMV was higher in children (3.0/100 patient years) than adults (0.46/100 patient years, incident rate ratio of 6.52). The absence of TT-CMV over 11 years suggests neither seronegative blood products nor CMV DNA blood donor screening would provide significant incremental safety when blood is already leukoreduced. D-/R- SOT recipients, particularly children, have a significantly higher and ongoing risk of CA-CMV.

Epidemiology, risk factors, and outcomes associated with cytomegalovirus in adult kidney transplant recipients: A systematic literature review of real-world evidence

Kidney transplant recipients (KTRs) have increased risk for cytomegalovirus (CMV) infection/disease given the necessity of drug-induced immunosuppression. A comprehensive review of published literature reporting real-world data on prevention strategies utilized and associated CMV burden outcomes is limited. Such data could help inform future clinical practice and identify unmet needs in CMV management. We conducted a systematic review of observational studies published in Medline or EMBASE from January 2008 to November 2018 to identify current real-world CMV management approaches, CMV infection/disease risk factors, and outcomes associated with CMV infection. Descriptive statistics and pooled quantitative analyses were conducted. From 1608 records screened, 86 citations, including 69 803 adult KTR, were included. Prophylaxis and preemptive therapy (PET) were predominant approaches among D+/R- and R + CMV serostatus transplants, respectively. Valganciclovir and ganciclovir were frequently utilized across CMV risk strata. Despite prevention approaches, approximately one-fourth of KTR developed CMV infection. Age and D+/R- CMV serostatus were consistent risk factors for CMV infection/disease. CMV infection/disease was associated with increased mortality and graft loss. CMV was similarly associated with acute rejection (AR) risk, but with high heterogeneity among studies. Limited data were available on CMV and opportunistic infections (OIs) risk. CMV remains a significant issue. New strategies may be needed to optimize CMV management.

Revisiting cytomegalovirus serostatus and replication as risk factors for inferior long-term outcomes in the current era of renal transplantation

BACKGROUND

Cytomegalovirus (CMV) serostatus and CMV replication are considered as risk factors for inferior graft and patient survival after renal transplantation, but long-term outcome data are limited. The aim of this retrospective single-centre study was to investigate the impact of CMV serostatus and CMV replication/disease on long-term outcomes in a well-defined cohort managed by a standardized CMV prevention/treatment protocol.

METHODS

We investigated 599 consecutive kidney transplantations having a CMV prevention protocol consisting of either prophylaxis (D+/R- and R+ with ATG induction) or screening/deferred therapy (R+ without ATG induction). Patients were grouped according to CMV serostatus [high risk (D+/R-): n = 122; intermediate risk (R+): n = 306; low risk (D-/R-): n = 171] and occurrence of CMV replication/disease (no CMV replication: n = 419; asymptomatic CMV replication: n = 110; CMV syndrome: n = 39; tissue-invasive CMV disease: n = 31). The median follow-up time was 6.5 years.

RESULTS

Graft and patient survival were not different among the three CMV serostatus groups as well as the four CMV replication/disease groups (P ≥ 0.44). Eighty-seven patients died, 17 due to infections (21%), but none was attributable to CMV. The overall hospitalization incidence for CMV-related infection was 3% (17/599 patients). The incidence of clinical and (sub)clinical rejection was similar among the groups (P ≥ 0.17). In a multivariate Cox proportional hazard model, neither CMV serostatus, nor CMV replication, nor CMV disease were independent predictors for patient death or graft failure, respectively.

CONCLUSIONS

This retrospective single-centre study suggests that the negative impact of CMV infection on long-term patient and allograft survival as well as on allograft rejection can be largely eliminated with current diagnostic/therapeutic management.

New treatments for cytomegalovirus in transplant patients

PURPOSE OF REVIEW

The purpose of this review is to highlight novel advances in prophylaxis against and treatment of CMV in kidney transplant recipients. Current options include intravenous ganciclovir and oral valganciclovir, but use of these agents is limited by side effects, such as myelosuppression as well as evolving resistance in CMV strains.

RECENT FINDINGS

Advances in the field include novel drugs that have shown promise in preliminary studies and are now being tested in large-scale clinical trials. Moreover, there is a developing focus in enhancing host immune responses to better protect against viral infection using anti-CMV vaccines. Studying host immune responses to CMV has also led to improved monitoring strategies, such as the QuantiFERON assay, which will allow for improved risk stratification and targeted therapies in transplant recipients.

SUMMARY

In summary, although options for prophylaxis and treatment against CMV have been somewhat limited to date, a number of new strategies are currently under development with several drugs in phase 3 trials. Therefore, the landscape of CMV management in kidney transplant recipients will be changing significantly in the coming years with the ultimate goal of safer and more effective therapies to combat CMV.

Clinical experience with a novel assay measuring cytomegalovirus (CMV)-specific CD4+ and CD8+ T-cell immunity by flow cytometry and intracellular cytokine staining to predict clinically significant CMV events

BACKGROUND

Cytomegalovirus (CMV) infection is one of the most common opportunistic infections following organ transplantation, despite administration of CMV prophylaxis. CMV-specific T-cell immunity (TCI) has been associated with reduced rates of CMV infection. We describe for the first time clinical experience using the CMV T-Cell Immunity Panel (CMV-TCIP), a commercially available assay which measures CMV-specific CD4+ and CD8+ T-cell responses, to predict clinically significant CMV events.

METHODS

Adult (> 18-year-old) patients with CMV-TCIP results and ≥ 1 subsequent assessment for CMV DNAemia were included at Brown University and the University of Maryland Medical Center-affiliated hospitals between 4/2017 and 5/2019. A clinically significant CMV event was defined as CMV DNAemia prompting initiation of treatment. We excluded indeterminate results, mostly due to background positivity, allogeneic hematopoetic cell transplant (HCT) recipients, or patients who were continued on antiviral therapy against CMV irrespective of the CMV-TCIP result, because ongoing antiviral therapy could prevent a CMV event.

RESULTS

We analyzed 44 samples from 37 patients: 31 were solid organ transplant recipients, 4 had hematologic malignancies, 2 had autoimmune disorders. The CMV-protection receiver operating characteristic (ROC) area under the curve (AUC) was significant for %CMV-specific CD4+ (AUC: 0.78, P < 0.001) and borderline for CD8+ (AUC: 0.66, P = 0.064) T-cells. At a cut-off value of 0.22% CMV-specific CD4+ T-cells, positive predictive value (PPV) for protection against CMV was 85% (95%CI 65-96%), and negative predictive value (NPV) was 67% (95%CI 41-87%).

CONCLUSIONS

The CMV-TCIP, in particular %CMV-specific CD4+ T-cells, showed good diagnostic performance to predict CMV events. The CMV-TCIP may be a useful test in clinical practice, and merits further validation in larger prospective studies.

Assessment and prevention of cytomegalovirus infection in allogeneic hematopoietic stem cell transplant and in solid organ transplant: A multidisciplinary consensus conference by the Italian GITMO, SITO, and AMCLI societies

Cytomegalovirus (CMV) remains a major cause of morbidity and mortality in allogeneic hematopoietic stem cell transplantation (allo-HSCT) and solid organ transplantation (SOT) recipients. In view of the uncertainties on the assessment and prevention of CMV infection in both transplant procedures, three Italian scientific societies for HSCT and SOT and for Clinical Microbiology appointed a panel of experts to compose a framework of recommendations. Recommendations were derived from a comprehensive analysis of the scientific literature and from a multidisciplinary consensus conference process. The lack of adequate clinical trials focused on certain diagnostic procedures, and antiviral intervention forced the panel to use the methods of consensus for shaping some recommendations. Recommendations concerning the two types of transplant were given for the following issues: assessment of pretransplant CMV serostatus, immunological monitoring after transplant, CMV prophylaxis with antivirals, CMV preemptive strategy, and CMV prophylaxis with immunoglobulin infusion and with adoptive immunotherapy. The questions raised by and the recommendations resulting from this consensus conference project may contribute to the improvement of certain crucial aspects of the management of CMV infections in allo-HSCT and in SOT populations.

Effect of Type of Dialysis on CMV-Specific CD8+ T Cells in Kidney Transplant Candidates

Background: Dialysis is the first procedure to partially replace renal function in end-stage renal diseases, despite several adverse side effects, such as infections. The primary aim of this study was to evaluate the levels of immune CMV-specific CD8+ T cells in a representative cohort of pre-transplant patients receiving hemodialysis (HD) or peritoneal dialysis (PD). The secondary aim was to monitor the CMV-specific CD8+ T cells in kidney transplant recipients undergoing different types of dialysis during the first year following their transplant.

Methods: Sixty-nine patients were enrolled and examined with respect to the type of dialysis they received. HLA class I dextramers for CMV were used to determine the quantity of CMV-specific CD8+ T cells. The CMV DNA viral load was also determined. Forty-two of the patients enrolled in the study underwent solid organ transplantation and were analyzed during their first year post-transplantation.

Results: Patients receiving HD had fewer CMV-specific CD8+ T cells than those in PD (p < 0.05). We also observed that patients in PD had more CMV-specific CD8+ T cells during the follow-up period than those in HD (p < 0.05), independently of the CMV DNA. Finally, PD patients had a higher frequency of CD8+ Effector-Memory RA T cells (TEMRA) and a lower frequency of central memory T cells (TCM) than did HD patients.

Conclusions: These results indicate the better status of CMV-specific T cell immunity in PD patients. The use of CMV T cell dextramers would be advantageous for monitoring the CD8+ T-specific response, enabling the use of prophylactic treatment to be optimized.

Comprehensive Characterization of a Next-Generation Antiviral T-Cell Product and Feasibility for Application in Immunosuppressed Transplant Patients

Viral infections have a major impact on morbidity and mortality of immunosuppressed solid organ transplant (SOT) patients because of missing or failure of adequate pharmacologic antiviral treatment. Adoptive antiviral T-cell therapy (AVTT), regenerating disturbed endogenous T-cell immunity, emerged as an attractive alternative approach to combat severe viral complications in immunocompromised patients. AVTT is successful in patients after hematopoietic stem cell transplantation where T-cell products (TCPs) are manufactured from healthy donors. In contrast, in the SOT setting TCPs are derived from/applied back to immunosuppressed patients. We and others demonstrated feasibility of TCP generation from SOT patients and first clinical proof-of-concept trials revealing promising data. However, the initial efficacy is frequently lost long-term, because of limited survival of transferred short-lived T-cells indicating a need for next-generation TCPs. Our recent data suggest that Rapamycin treatment during TCP manufacture, conferring partial inhibition of mTOR, might improve its composition. The aim of this study was to confirm these promising observations in a setting closer to clinical challenges and to deeply characterize the next-generation TCPs. Using cytomegalovirus (CMV) as model, our next-generation Rapamycin-treated (Rapa-)TCP showed consistently increased proportions of CD4⁺ T-cells as well as CD4⁺ and CD8⁺ central-memory T-cells (T_CM). In addition, Rapamycin sustained T-cell function despite withdrawal of Rapamycin, showed superior T-cell viability and resistance to apoptosis, stable metabolism upon activation, preferential expansion of T_CM, partial conversion of other memory T-cell subsets to T_CM and increased clonal diversity. On transcriptome level, we observed a gene expression profile denoting long-lived early memory T-cells with potent effector functions. Furthermore, we successfully applied the novel protocol for the generation of Rapa-TCPs to 19/19 SOT patients in a comparative study, irrespective of their history of CMV reactivation. Moreover, comparison of paired TCPs generated before/after transplantation did not reveal inferiority of the latter despite exposition to maintenance immunosuppression post-SOT. Our data imply that the Rapa-TCPs, exhibiting longevity and sustained T-cell memory, are a reasonable treatment option for SOT patients. Based on our success to manufacture Rapa-TCPs from SOT patients under maintenance immunosuppression, now, we seek ultimate clinical proof of efficacy in a clinical study.

New Developments in the Management of Cytomegalovirus Infection After Transplantation

Cytomegalovirus (CMV) continues to be one of the most important pathogens that universally affect solid organ and allogeneic hematopoietic stem cell transplant recipients. Lack of effective CMV-specific immunity is the common factor that predisposes to the risk of CMV reactivation and clinical disease after transplantation. Antiviral drugs are the cornerstone for prevention and treatment of CMV infection and disease. Over the years, the CMV DNA polymerase inhibitor, ganciclovir (and valganciclovir), have served as the backbone for management, while foscarnet and cidofovir are reserved for the management of CMV infection that is refractory or resistant to ganciclovir treatment. In this review, we highlight the role of the newly approved drug, letermovir, a viral terminase inhibitor, for CMV prevention after allogeneic hematopoietic stem cell transplantation. Advances in immunologic monitoring may allow for an individualized approach to management of CMV after transplantation. Specifically, the potential role of CMV-specific T-cell measurements in guiding the need for the treatment of asymptomatic CMV infection and the duration of treatment of CMV disease is discussed. The role of adoptive immunotherapy, using ex vivo-generated CMV-specific T cells, is highlighted. This article provides a review of novel drugs, tests, and strategies in optimizing our current approaches to prevention and treatment of CMV in transplant recipients.

CMV-specific Cell-mediated Immunity at 3-month Prophylaxis Withdrawal Discriminates D+/R+ Kidney Transplants at Risk of Late-onset CMV Infection Regardless the Type of Induction Therapy

BACKGROUND

Whether cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) at prophylaxis cessation predicts D+/R+ kidney transplants at risk of late-onset CMV infection after receiving distinct induction therapies is still not well characterized.

METHODS

We prospectively assessed CMV-specific CMI predicting late-onset CMV infection at prophylaxis withdrawal and at earlier time-points, in 96 consecutive D+/R+ patients receiving either anti-interleukin 2-receptor antibody (anti-IL2RA; n = 50) or rabbit antithymoglobulin (n = 46). CMV-specific CMI was evaluated against CMV antigens (IE-1, pp65) using an IFN-γ ELISpot assay.

RESULTS

Fourteen (14.6%) of 96 patients developed late-onset CMV infection and 2 (2.1%) of 96 displayed disease. At 3 months, CMV-specific CMI frequencies were significantly lower in patients developing late-onset CMV infection (P < 0.001 for IE-1, P = 0.030 for pp65), regardless the type of induction therapy. Receiver operating characteristic curve analyses showed accurate CMV-specific CMI cutoffs (25 and 130 IFN-γ spots for IE-1 and pp65, respectively) classifying patients into high risk, intermediate risk, or low risk (log-rank = 0.006; hazard ratio, 4.084; 95% confidence interval, 1.431-11.651; P = 0.009), being IE-1 CMI the strongest predictor (odds ratio, 5.554; 95% confidence interval, 1.486-20.766; P = 0.011). Although the profound posttransplant CMV-specific CMI inhibition among rabbit antithymocyte globulin-treated patients precludes its use for risk stratification both before and early after kidney transplant, a similar proportion of at-risk patients could be identified before month 3 within anti-interleukin 2-receptor antibody-treated patients.

CONCLUSIONS

Monitoring CMV-specific CMI at 3-month prophylaxis cessation discriminates kidney transplant recipient at risk of late-onset CMV infection, regardless the type of induction therapy.

Diagnostic performance of cytomegalovirus (CMV) immune monitoring with ELISPOT and QuantiFERON-CMV assay in kidney transplantation: A PRISMA-compliant article

BACKGROUND

Cytomegalovirus (CMV) infection is part of major infection complications following kidney transplantation. However, more rapid and low-complexity assays are needed for CMV infection. Our study is to investigate the diagnostic efficacy of 2 novel tests, CMV-ELISPOT and QuantiFERON-CMV tests, in CMV DNA viremia and CMV infection following renal transplant.

METHODS

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the Web of Science. Case-control or cohort study designed to explore the CMV-ELISPOT and/or QuantiFERON-CMV tests in the recipients with CMV infection was considered to be eligible for this study. Sensitivity (SEN), specificity (SPE), diagnostic odds ratio (DOR), and summary receiver-operating characteristic (SROC) curves were calculated.

RESULTS

We selected a total of 12 articles for systematic review and 11 of them were included in meta-analysis. For CMV-pp65 assay, the pooled SEN, SPE, and DOR were 0.73 (95% confidence interval [CI], 0.67-0.78), 0.61 (95% CI, 0.56-0.65), and 4.46 (95% CI, 3.11-6.39), respectively. For CMV-IE-1 assay, the pooled SEN, SPE, and DOR were 0.84 (95% CI, 0.78-0.88), 0.46 (95% CI, 0.42-0.51), and 5.07 (95% CI, 3.26-7.89), respectively, whereas the pooled SEN, SPE, and DOR of QuantiFERON-CMV test were 0.38 (95% CI, 0.28-0.49), 0.38 (95% CI, 0.32-0.44), and 1.02 (95% CI, 0.17-6.00).

CONCLUSIONS

We reported that CMV-ELISPOT tests, including CMV-pp65 and CMV-IE-1, perform well in the diagnosis and prediction of CMV infection in renal transplant recipients, whereas QuantiFERON-CMV test needs further exploration.

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Despite recent advances, cytomegalovirus (CMV) infections remain one of the most common complications affecting solid organ transplant recipients, conveying higher risks of complications, graft loss, morbidity, and mortality. Research in the field and development of prior consensus guidelines supported by The Transplantation Society has allowed a more standardized approach to CMV management. An international multidisciplinary panel of experts was convened to expand and revise evidence and expert opinion-based consensus guidelines on CMV management including prevention, treatment, diagnostics, immunology, drug resistance, and pediatric issues. Highlights include advances in molecular and immunologic diagnostics, improved understanding of diagnostic thresholds, optimized methods of prevention, advances in the use of novel antiviral therapies and certain immunosuppressive agents, and more savvy approaches to treatment resistant/refractory disease. The following report summarizes the updated recommendations.

Going beyond serology for stratifying the risk of CMV infection in transplant recipients

Knowledge of donor and recipient (D/R) cytomegalovirus (CMV) serostatus is critical for risk stratification of CMV infection and disease in transplant recipients, particularly in the solid organ transplantation (SOT) setting. Despite its broad availability and the success of it use, the risk stratification based on the D/R serostatus is not free of limitations since there are a nondepreciable number of patients that are not accurately categorized by this approach. In fact, up to 20% of seropositive SOT recipients, classically considered at intermediate risk, develop episodes of CMV infection and disease after transplantation. Here, we provide an overview of additional donor and recipient factors that may have utility in identifying patients at risk for post-transplant CMV infection. Specifically, we summarize our current understanding regarding the potential use of use CMV-specific T-cell-mediated immunity, neutralizing antibodies and host genetics that may influence the risk of CMV infection and disease. We provide an overview of the benefits and limitations associated with using these immunological factors in risk stratification and propose specific variables that could be analyzed at the pretransplant evaluation to improve the identification of patients with increased individual susceptibility.

Impact of pretransplant CMV-specific T-cell immune response in the control of CMV infection after solid organ transplantation: a prospective cohort study

INTRODUCTION

Although solid organ transplant (SOT) recipients with pretransplant serology for cytomegalovirus (CMV-R+) are considered at intermediate risk for CMV infection post transplantation, CMV infection remains a major cause of morbidity in this population. We prospectively characterized whether having pretransplant CMV-specific cellular immunity is independently associated with controlling infection after transplantation in R + SOT recipients.

METHODS

A prospective cohort of consecutive R + SOT recipients that received pre-emptive treatment for CMV infection was monitored after transplantation and variables were recorded during the follow-up. The cytomegalovirus-specific T-cell immune response was characterized by intracellular cytokine staining and viral loads determined using real-time PCR.

RESULTS

One hundred and thirty-five R + SOT recipients were included (67 kidney, 64 liver, four liver-kidney). Only one-third of the patients (42; 31.85%) had CMV-specific T-cell immunity (CD8⁺CD69⁺INF-γ⁺ T cells >0.25%) before transplantation. Patients with negative pretransplant immunity had more CMV infection (49, 52.7% vs. 15, 35.7%; p 0.07) and received more antiviral therapy than those with immunity (32, 34.4% vs. 6, 14.3%, p 0.016). Having CMV specific immunity was an independent factor for protection from developing viraemia ≥2000 IU/mL (OR 0.276, 95% CI 0.105-0.725, p < 0.01) and lower administration of treatment (OR 0.398, 95% CI 0.175-0.905, p 0.028). Only patients with no pretransplant CMV-specific T-cell response were diagnosed with CMV-disease (8, 8.6% vs. 0, 0%, p 0.05).

DISCUSSION

Our results show that having a pretransplant CMV specific T-cell response may be associated with a lower rate of CMV viraemia and less antiviral treatment after transplantation; however, more prospective studies are needed to confirm these findings.

Native kidney cytomegalovirus nephritis and cytomegalovirus prostatitis in a kidney transplant recipient

We present a case of cytomegalovirus (CMV) native kidney nephritis and prostatitis in a CMV D+/R- kidney transplant recipient who had completed six months of CMV prophylaxis four weeks prior to the diagnosis of genitourinary CMV disease. The patient had a history of benign prostatic hypertrophy and urinary retention that required self-catheterization to relieve high post-voiding residual volumes. At 7 months post-transplant, he was found to have a urinary tract infection, moderate hydronephrosis of the transplanted kidney, and severe hydroureteronephrosis of the native left kidney and ureter, and underwent native left nephrectomy and transurethral resection of the prostate. Histopathologic examination of kidney and prostate tissue revealed CMV inclusions consistent with invasive CMV disease. This case highlights that CMV may extend beyond the kidney allograft to involve other parts of the genitourinary tract, including the native kidneys and prostate. Furthermore, we highlight the tissue-specific risk factors that preceded CMV tissue invasion. In addition to concurrent diagnoses, health care providers should have a low threshold for considering late-onset CMV disease in high-risk solid organ transplant recipients presenting with signs and symptoms of genitourinary tract pathology.

New therapies for human cytomegalovirus infections

The recent approval of letermovir marks a new era of therapy for human cytomegalovirus (HCMV) infections, particularly for the prevention of HCMV disease in hematopoietic stem cell transplant recipients. For almost 30 years ganciclovir has been the therapy of choice for these infections and by today's standards this drug exhibits only modest antiviral activity that is often insufficient to completely suppress viral replication, and drives the selection of drug-resistant variants that continue to replicate and contribute to disease. While ganciclovir remains the therapy of choice, additional drugs that inhibit novel molecular targets, such as letermovir, will be required as highly effective combination therapies are developed not only for the treatment of immunocompromised hosts, but also for congenitally infected infants. Sustained efforts, largely in the biotech industry and academia, have identified additional highly active lead compounds that have progressed into clinical studies with varying levels of success and at least two have the potential to be approved in the near future. Some of the new drugs in the pipeline inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapeutic regimens. Here, we will describe some of the unique features of HCMV biology and discuss their effect on therapeutic needs. Existing drugs will also be discussed and some of the more promising candidates will be reviewed with an emphasis on those progressing through clinical studies. The in vitro and in vivo antiviral activity, spectrum of antiviral activity, and mechanism of action of new compounds will be reviewed to provide an update on potential new therapies for HCMV infections that have progressed significantly in recent years.

Regular monitoring of cytomegalovirus-specific cell-mediated immunity in intermediate-risk kidney transplant recipients: predictive value of the immediate post-transplant assessment

OBJECTIVE

Previous studies on monitoring of post-transplant cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) are limited by single-centre designs and disparate risk categories. We aimed to assess the clinical value of a regular monitoring strategy in a large multicentre cohort of intermediate-risk kidney transplant (KT) recipients.

METHODS

We recruited 124 CMV-seropositive KT recipients with no T-cell-depleting induction pre-emptively managed at four Spanish institutions. CMV-specific interferon-γ-producing CD4⁺ and CD8⁺ T cells were counted through the first post-transplant year by intracellular cytokine staining after stimulation with pp65 and immediate early-1 peptides (mean of six measurements per patient). The primary outcome was the occurrence of any CMV event (asymptomatic infection and/or disease). Optimal cut-off values for CMV-specific T cells were calculated at baseline and day 15.

RESULTS

Twelve-month cumulative incidence of CMV infection and/or disease was 47.6%. Patients with pre-transplant CMV-specific CD8⁺ T-cell count <1.0 cells/μL had greater risk of CMV events (adjusted hazard ratio (aHR) 2.84; p 0.054). When the CMI assessment was performed in the immediate post-transplant period (day 15), the presence of <2.0 CD8⁺ T cells/μL (aHR 2.18; p 0.034) or <1.0 CD4⁺ T cells/μL (aHR 2.43; p 0.016) also predicted the subsequent development of a CMV event. In addition, lower counts of CMV-specific CD4⁺ (but not CD8⁺) T cells at days 60 and 180 were associated with a higher incidence of late-onset events.

CONCLUSIONS

Monitoring for CMV-specific CMI in intermediate-risk KT recipients must be regular to reflect dynamic changes in overall immunosuppression and individual susceptibility. The early assessment at post-transplant day 15 remains particularly informative.

Cytomegalovirus infection in heart transplantation: A single center experience

BACKGROUND

Cytomegalovirus (CMV) infection remains a major complication after heart transplantation with varying prophylaxis strategies employed. We sought to determine the impact of valganciclovir (VGC) duration on the epidemiology of CMV infections after heart transplantation.

METHODS

We performed a prospective cohort study of CMV donor (D) or recipient (R) seropositive heart transplant recipients from 2005 to 2012 who completed VGC prophylaxis, ranging from 3 to 12 months according to serostatus and induction immunosuppression. Univariate and multivariate logistic regression was performed.

RESULTS

Among 159 heart transplant recipients during the study period, 130 (82%) were eligible for VGC prophylaxis. CMV D/R serostatus was as follows: 24% D+/R-, 30% D+/R+, and 29% D-/R+. 65% and 21% received basiliximab and thymoglobulin induction, respectively, followed by maintenance tacrolimus, mycophenolate mofetil, and prednisone. Twenty-one (16%) recipients suffered CMV infection. There was no association with comorbidities including diabetes mellitus, chronic kidney disease, or mechanical assist devices, nor were there associations with rejection, treatments of rejection, or mortality. When VGC prophylaxis duration was stratified by ≤6 vs ≥12 months, time from heart transplantation to CMV infection was delayed (median 247 vs 452 days, P = .002) but there was no difference in days from VGC discontinuation to onset of CMV infection (median 72 vs 83 days, P = .31). CMV infection occurred most frequently within 6-16 weeks of VGC cessation, and 95% of infections occurred during the 6 months post-prophylaxis period.

CONCLUSIONS

Relative to ≤6 months, ≥12 months of VGC did not reduce incidence of CMV infection and only delayed time to onset. 95% of CMV infection occurs within 6 months after cessation of VGC.

Immune Monitoring for CMV in Transplantation

PURPOSE OF REVIEW

Immune monitoring to determine when and how the recovery of cytomegalovirus (CMV)-specific T-cells occurs post-transplantation may help clinicians to risk stratify individuals at risk of complications from CMV. We aimed to review all recent clinical studies using CMV immune monitoring in the pre- and post-transplant setting including the use of recently developed standardized assays (Quantiferon-CMV and the CMV ELISPOT) to better understand in whom, when, and how immune monitoring is best used.

RECENT FINDINGS

Pre-transplant assessment of CMV immunity in solid-organ transplant recipients where CMV seropositive recipients had undetectable cell-mediated responses despite past immunity has shown that they are at a much higher risk of developing CMV reactivation. Post-transplant CMV immune monitoring can guide (shorten or prolong) the duration of antiviral prophylaxis, identify recipients at risk of post-prophylaxis CMV disease, and predict recurrent CMV reactivation. Thus, CMV immune monitoring, in addition to current clinical and DNA-based monitoring for CMV, has the potential to be incorporated into routine clinical care to better improve CMV management in both the stem and solid-organ transplant population.